alhosn university journal of engineering & applied sciences

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ISSN 2076-8516

ISSN 2076-8516

www.alhosnu.ae

ALHOSN UNIVERSITY

JOURNAL OF

ENGINEERING

& APPLIED

SCIENCES

Volume 3 Number 2 February 2011Digital divide: A problem of access or use of ICT: The case of academic institutions in TunisiaHusam-Aldin N. Al Malkawi, Abir Ben Haj Hamida, Rekha Pillai

A comparison of general design and load requirements in building codes in Canada and SyriaSamer Al-Martini

Analysis of soil media containing cavities or tunnels by the boundary element methodOmar Al-Farouk S. Al-Damluji, Mohammed Y. Fattah, Rana A.J. Al-Adthami

Guidelines for implementing pipeline integrity towards minimization of hazardous accidents with practical and industrial case studiesM. El-Gammal (Sr.) H. El Naggar, M.M. El-Gammal (Jr.)

Durability of Concrete Structures in Arabian Gulf: State of the Art and Improved SchemeReem Sabouni

Cad and 3D visualization software in design education: Is one package enough? Seif Khiati

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ALHOSN UNIVERSITY JOURNALOF ENGINEERING AND APPLIED SCIENCES

ADVISORY BOARD(in alphabetical order)

Prof. Ghassan AouadSalford University, UK

Prof. Goodarz AhmadiClarkson University, USA

Prof. Hisham ElkadiUniversity of Ulster, UK

Prof. Jamal A. AbdallaAmerican University of Sharjah, UAE

Dr. Khaled El-SawyUnited Arab Emirates University, UAE

Dr. Mohamed LachemiRyerson University, Canada

Prof. Mufid Abdul Wahab SamaraiSharjah University, UAE

Prof. Nizar Al-HolouUniversity of Detroit Mercy, USA

Prof. Riadh Al-MahaidiMonash University, Austrialia

Prof. Sadik DostUniversity of Victoria, Canada

Prof. Ziad SaghirRyerson University, Canada

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ALHOSN UNIVERSITYJOURNAL OFENGINEERING& APPLIEDSCIENCES

A bi annual, refereed journal published byALHOSN University - Abu Dhabi - UAE

Volume 3 Number 2 Feb. 2011

ChairmanDr. Nasser Bin Saif Al Mansoori

EditorProf. Abdul Rahim Sabouni

Associate EditorDr. Hamdi Sheibani

MembersDr. Adel KheliDr. Adnan HusneinDr. Abdelaziz SoufyaneDr. Naima Benkari

Managing EditorDr. Al Haj Salim Mustafa

Address:P.O. Box : 38772Abu Dhabi - UAETel. : +971 2 4070700Fax : +971 2 4070799E-mail : [email protected] : www.alhosnu.ae

ISSN 2076-8516

book.indd 3 7/27/10 5:01 PM

February 2011

AHU J. of Engineering & Applied Sciences 3 (2) 2011© 2010 ALHOSN University

CONTENTS

Digital divide: A problem of access or use of ICT: The case of academic institutions 7in TunisiaHusam-Aldin N. Al Malkawi, Abir Ben Haj Hamida, Rekha Pillai

A comparison of general design and load requirements in building codes in Canada 19and SyriaSamer Al-Martini

Analysis of soil media containing cavities or tunnels by the boundary 27element methodOmar Al-Farouk S. Al-Damluji, Mohammed Y. Fattah, Rana A.J. Al-Adthami

Guidelines for implementing pipeline integrity towards minimization of 51hazardous accidents with practical and industrial case studiesM. El-Gammal (Sr.) H. El Naggar, M.M. El-Gammal (Jr.)

Durability of Concrete Structures in Arabian Gulf: State of the Art and 73Improved SchemeReem Sabouni

Cad and 3D visualization software in design education: Is one package enough? 91Seif Khiati

6 7

____________________________________________* Corresponding Author.Tel.: +971 4070568, E-mail : [email protected]

* Corresponding Author. Tel.: +971 4070568 E‐mail: [email protected]

DIGITAL DIVIDE: A PROBLEM OF ACCESS OR USE OF ICT: THE CASE OF ACADEMIC INSTITUTIONS IN TUNISIA

Husam-Aldin N. Al Malkawi1*, Abir Ben Haj Hamida1, Rekha Pillai1 1Faculty of Business, ALHOSN University, P. O. Box: 38772, Abu Dhabi, U.A.E.

ABSTRACT: This paper examines the causes of digital divide in a developing country using Tunisia as a case study. The development of information and communication technologies (ICTs) took place exponentially resulting in the emergence of digital divide. A new form of illiteracy is emerging with respect to difficulty of access to information, difficulty of being informed and incapability for initiating innovative approaches. This study focuses on access and use of ICT by instructors in academic institutions in Tunisia. A questionnaire was developed and distributed to 100 instructors in Sfax University (Tunisia), to infer the computer skills of teachers and their use of ICT. It aims to determine the difference in the extent of ICT usage for personal and educational purposes by instructors and the attitude of various stakeholders towards the integration of ICT in education. A discriminant analysis was further employed to interpret the results of the findings. The main finding of this paper is that the problem is more related to the use rather than the access to ICT. Also, the result shows that the majority of instructors acquired only basic skills for the usage of ICT in their teaching. A significant disparity was noticed in the optimum use of ICT in the sense that only a limited percentage of ICT was being devoted for knowledge enhancement, the majority, however, being utilized for social networking. KEYWORDS: ICT, digital divide, Access to ICT, Use of ICT, Tunisia.

1. INTRODUCTION

Information Communication Technology (ICT) acts as a corner stone to generate, acquire, preserve, manage, process, display and disseminate information. With the magnitude of their impact on society and particularly in the educational environment, ICTs have the potential to be a radical innovation, revolution or a paradigm shift.

The use of ICT by individuals, groups or organizations has particular importance since it is subject to factors relevant to behavior and assessment of individuals. Its application to the higher educational sector and research enables students to update and improve the quality of their knowledge and attain their vision of career enhancement.

In Tunisia, development of ICT has evolved as a strategy which aims primarily to make the country technologically competent in order to withstand foreign competition. Thus, we cannot overlook the fact that education plays a major role in the evolution of a country that is committed to achieve global excellence. In this way, the Ministry of Higher Education, Scientific Research and Technology seeks to make ICT more accessible through increased investment, research and training in this area. The integration of ICT in education is dependent on the behavior, qualification and attitudes of teachers. They play the role of intermediary between academic institutions (resources) and students (potential users). For this reason, the sample of our study will be teachers in higher education.

This paper is based on an analysis of issues related to ICT access and use within academic institutions in Tunisia. The main aim of the study is to arrive at an answer to the question

AHU J. of Engineering & Applied Sciences 3 (2) : 7-18 (2011)© 2010 ALHOSN University

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pertaining to whether the digital divide is an issue related to access or application. The choice of this issue has been inspired by the importance of the subject since the holding of the 2nd phase of World Summit of Information System in Tunisia and the emergence of ICT subject at lower levels in the Tunisian education system. Moreover, lack of sufficient research in the field of digital divide in developing countries, especially Tunisia, has prompted our current study. The main finding of this paper is that the problem is more related to the use rather than the access to ICT. Also, the result reveals that the majority of instructors acquired only basic skills for the usage of ICT in their teaching.

The remainder of this paper is structured as follows. Section 2 reviews some of the previous studies relating to digital divide. Section 3 states the methodology adopted in this study. Section 4 presents the analysis and findings, Section 5 concludes the paper and Section 6 includes the references.

2. LITERATURE REVIEW

The digital divide is a new term emerged with the emergence of ICT. It is generally defined as the difference in access between rich and poor countries in term of ICT. It encompasses both the differences in access to technology among individuals and the gap between nations that have and those who do not have the technology [4].

The measurement of digital divide was originally based on traditional quantitative indicators such as internet penetration, number of personal computers and volume of e-commerce. The reason for this gap can be explained in several countries not only by deficiencies in communications infrastructure or low incomes, but also due to the emergence of qualitative factors like illiteracy, culture, and language. A study by Looker and Thiessen [8] addressed a different aspect of digital divide and arrived at the existence of two dimensions in digital divide. The first dimension was related to access to computers and ICT, and the second related to the extent of computer usage at school and at home. Thus it can be concluded that the issue of digital divide is not limited to access to ICT but also to its extent of application.

However Renaud and Torres [11] define access to content as a stage separate from access to physical infrastructure. The technology imparts information and what differs from one to the other is access to this information regardless of computer equipment, so the only access to knowledge in this way allows distinguishing those who did not. In addition, developed countries exert great pressure on developing countries to deliver their data reflecting their own characteristics and they overpower these countries by concepts and models of development that may not be applicable to their environment.

A further study by Baile and Lefievre [1] noted that the success of ICT is dependent on the understanding of the necessity of its importance and the simplicity of its attributes. So, beyond the digital divide already known and defined in terms of access to ICTs, there is a divide more important that is the quality of ICT use. A gap may exist between users and non users. It can be also among the users as some are intensive users while the others are users of low dose [10].

HUSAM-ALDIN N. AL MALKAWI, ABIR BEN HAJ HAMIDA, REKHA PILLAI

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Komis [5] and Makrakis [9] based their studies on an analysis of school practices of various developed countries and proposals made by committees of experts and arrived at three models which were related to the introduction and integration of ICT into education systems. The first model considers ICT as a teaching subject. It suggests imparting computer knowledge by considering IT as a separate discipline and promoting a process computer. The second model is the antithesis of the first and considers IT as a tool for teaching and learning in all disciplines and a means to an interdisciplinary approach and integral learning processes. The third model which encompasses the others is a result of the inability of a short-term application of the integrated approach, and the need to have a certain level of literacy, at least currently, concerning the use of the computer.

More recently, Lebrun [7] specified three different applications of ICT in education, which were the reactive, proactive and interactive mode respectively. The reactive mode regards ICT as resources for learning and therefore the emphasis is on information extracted from the environment (culture, knowledge etc) that has teachers or sources of knowledge such as media, database, encyclopedias, etc. to impart this information. The related teaching methods here are courses, presentations, lectures and exercise sessions.. The proactive mode specifies the objective from the use of ICT as manipulating the world and its representations. The emphasis is on the cognitive skills (analysis, synthesis, evaluation, critical thinking) that the learner will have to deploy into the environment. It is for the learner to reconstruct, to rediscover through the use of simulations (analysis) and modeling (synthesis) to solve problems and create projects.

The main tools employed are programming software, simulation and modeling software, compact disks and websites. The teaching methods which are related to this mode adopt problem solving approaches, project development, the real and virtual laboratories, etc. The Interactive mode aims to use ICT for mutual knowledge sharing. In this mode, the focus is more on interpersonal skills. This can be seen as the conjunction of the two previous modes with different versions of relational interactivity: 1) Immersion in an environment (role playing, interaction with virtual partners) 2) Interaction between distant partners (mail, news, listings and educational uses) 3) Interaction with local partners.

The digital pedagogy could be defined as the set of techniques, media and digital means currently being used to optimize the teaching-learning process. This pedagogy as articulated by Bloom [2] predicted that with sufficient time and resources, all students should be able to achieve all the objectives of a course. However, the percentage of failures might be relatively high. All the difficulties mentioned above largely explain why a large proportion of faculty is still very reluctant to integrate ICT in their daily teaching activities, and confined in far more traditional approaches. This is mainly due to lack of supervisors support, professional and technical support for the creation of teaching materials adapted to this new paradigm. The gap also widens due to the lack of studies based on Tunisia.

DIGITAL DIVIDE : A PROBLEM OF ACCESS OR USE OF ICT: THE CASE OF ACADEMIC INSTITUTIONS IN TUNISIA

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3. METHODOLOGY

The paper employed qualitative research design and descriptive statistics for the purpose of completing the study. A questionnaire was developed after having been inspired by the research done within the research group on the interdisciplinary in teaching education at the University of Shebrooke, Canada [6]. A pilot study was conducted by testing the questionnaire on a small number of instructors before conducting the main survey for testing errors in structure design and omissions, existence of ambiguity etc. It also helps to understand the extent of understandability of questions framed. Adequate Response categories were developed for questions in order to facilitate the process of coding and analysis.

This questionnaire was divided into four main parts. The first part was related to the description of the equipment in the institution and to the respondents' perception of these facilities. The second part addressed the ICT access in education. The third part dealt with the practical use of these tools, both personal and on the teaching practices. The fourth part included 7 items with a response forming an agreement scale in relation to ICT1.

The questionnaire was administered personally or by mail to the target sample of 100 instructors from a population of 530 instructors in the year 2007. The instructors belonged to SFAX University, Tunisia. The University encompasses 4 colleges, each specializing in different disciplines namely Natural Science, Social Science, Computer Science and Business. The sample was chosen by quota sampling following Charfi [3] in her study about the attitudes of teachers and researchers towards internet.

The data were processed according to the nature of the variables that determine them. Initially, we calculated the structures of frequencies and percentages for all items available for an overview of the study sample and to find out more of its characteristics. Discriminant analysis was later used to determine which continuous variables discriminate between two or more naturally occurring groups. There are several tests of significance, but we only present Wilks' lambda here. Wilks' lambda is used as a test of mean differences in Discriminant Analysis, such that the smaller the lambda for an independent variable, the more that variable contributes to the discriminant function. Lambda varies from 0 to 1. The F-test of Wilks' lambda shows which variables contributions are significant. The aim was to study the relationship between a qualitative variable and a set of quantitative variables and to find out the most discriminating variables in order to investigate if they are related to the access or the use of ICT.

1 The questionnaire is available upon request.


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4. ANALYSIS AND FINDINGS

This section will be devoted to the presentation and analysis of data collected by questionnaire at the survey which focuses on best practices for access and use of ICT in academic institutions. Firstly, we try to present frequencies calculated for different items in the questionnaire by using descriptive analysis. Secondly, we consider sex, age, rank and experience of instructors as independent variables and the below factors as dependant variable: 1) Use of audiovisual support 2) Possession of a computer at home 3) Possession of a computer in the office 4) Number of Internet connections per week 5) Number of use of emails per week 6) Mode of learning to use ICT 7) ICT Training 8) Use of communications software 9) Use of common software. These variables represent the practices of access and use of ICT by instructors in academic institutions. A positive response was received from 81 teachers out of the 100 questionnaires distributed. The whole survey was grouped under several headings such as the qualitative attributes of the respondents, description of ICT equipments in the institutions, access to ICT in education, use of ICT by teachers and the personal attitude towards ICT in education. 4.1 Findings on the qualitative attributes of the respondents The questionnaire began with general questions focusing on the gender, age, qualifications, and the title held in the Institution. This was to generalize the qualitative features of the respondents to arrive at conclusions whether these qualitative traits had any impact on the concept of ICT (Table 1).

Table 1. Demographic Specifications

Gender Frequency Percentage (%) Male 60 74.1 Female 21 25.9 Total 81 100

Age group 26 -30 6 7.4 31-40 26 32.1 41-50 38 46.9 51 plus 11 13.6 Total 81 100

Table 1 reports that males constituted 74.1% and females constituted 25.9% of the respondents. The most active participation of 46.9% was from instructors belonging to the age group between 41 and 50 years of age.


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This was solely due to the fact that the majority of the teachers had more than 10 years experience in the educational field. Thus they automatically fell under the title of Assistant, Associate or Full Professors. Table 2 revealed that 38.3 % of the respondents had a teaching experience between 11-20 years. These qualitative attributes signals that majority of respondents were experienced in the field of education and were resorting to the olden methods of teaching as the ICT revolution is a term more familiar to the new generation.

Table 2: Rank and Experience of Teachers Rank Frequency Percentage (%) Professor 8 9.9 Associate Professor 10 12.3 Assistant Professor 32 39.5 Instructor 31 38.3 Total 81 100 Number of years Less than 5 8 9.9 6-10 years 19 23.5 11-20 years 31 38.3 21 years and above 23 28.4 Total 81 100

4.2 Findings on ICT equipments in the Institutions

This section mainly dealt with questions related to the availability of hardware and software in the institutions as they were the prerequisites for the successful adoption of ICT. The findings on these aspects are reported in Table 3. Table 3: Availability of ICT

Frequency Percentage (%)

Is the library computerized

Positive 58 71.6

Negative 23 28.4

Total 81 100

Access to computers

Positive 51 63

Negative 30 37

Total 81 100

Existence of website

Positive 62 76.5

Negative 19 23.5

Total 81 100


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The first question put forth in examining the issues in ICT was if the institutions had a computerized library. 71.6% of the teachers reassured the above statement whereas 28.4% denied this fact. This meant that students had an option to widen their knowledge base in computers from the libraries. We can see that 63% of the teachers had accepted that they had access to computers while 37% did not. This was because only teachers with titles of associate and above were provided with a computer in their office. With regard to the question related to the existence of a website for their institution a positive response was received from 76.5% of the teachers. The remaining 23.5% teachers belonged to the Faculty of Humanities, which did not have a website of their own. This clearly reveals that the computerization was in progress and being adapted for enhancing information content. An opportunity to evaluate certain options such as the adequacy of computers, its power, and availability of software, networking of computers, speed and stability of internet connections provided a mixed response, the findings of which are shown in Table 4. Table 4: Results Summary of Responses from Teachers (Availability of ICT) Strongly disagree Disagree Agree Strongly agree

Freq % Freq % Freq % Freq % Adequate number of Computers

9 11.1 38 46.9 28 34.6 6 7.4

Computers are powerful

6 7.4 41 50.6 26 32.1 8 9.9

Software is updated

13 16 33 40.7 28 34.6 7 8.6

Computers are networked

1 1.2 26 32.1 33 40.7 21 25.9

Fast Internet connection

5 6.2 19 23.5 42 51.9 15 18.5

Internet connection is stable

8 9.9 20 24.7 38 46.9 15 18.5

Table 4 shows that more than 50% of the instructors expressed their dissatisfaction with the availability of computers, its power, and the non adoption of latest software. Nearly 50% of the teachers expressed satisfaction over the speed and stability of internet connections available to them. This proves that if the teachers are provided with adequate computers with sophisticated technology, there will be a positive and remarkable enhancement in the usage of ICT.

4.3 Findings on ICT in Teaching

In order to explore the perceptions related to wider access to ICT in education, questions pertaining to the usage of computers in disciplines other than computer science were


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administered to the subjects under study. An impressive response of 87.2% was received from respondents agreeing to the possibility of usage of IT in all disciplines. This reveals that ICT can be innovatively applied in all disciplines to ensure effective learning. The above response rate opens venues for further research regarding the extent of readiness to adopt ICT in education. The teachers were also asked to air their opinion on the favourability of inculcating digital technologies in education, the result of which is shown in Table 5.

Table 5: Usage of ICT

Table 5 reveals that nearly 54.3% were highly favouring the application of ICT in education and only a negligible rate of 3.7% of the respondents showed a neutral attitude towards the ICT. This can be attributed to age, subjective approach or the normal tendency to resist change. Another barrier in the implementation of ICT was the non availability of internet connections in classrooms which hampered the posting of the course material online. It also outlines the ignorance related to the application of ICT for enhancing the educational sector. Questions were also asked regarding the audio visual method used in class and 38.3% of the respondents admitted using the old fashioned overhead projector while 35.8% of the instructors refrained from using any audio visual aids. The teachers were asked to voice their opinion on what they considered the main obstacle to the use of ICT in education. Majority of the respondents attributed this hindrance to the lack of training imparted to instructors regarding the use of ICT. The second prominent factor accelerating the pace of hindrance was the inferior quality of existing equipments which were basically non user friendly. Teachers also expressed their concern over the lack of necessity to integrate the ICT in the curriculum. Of the few solutions offered to the teachers to overcome the obstacles, all of them substantiated the necessity of the provision of adequate computers as the primary step to mitigate this digital gap and emphasised the importance of making the educational content suitable and available for classroom use through ICT. These results underline the fact of non availability of adequate equipments, lack of proper training and support and the non integration of ICT methods in teaching as the major facts widening the digital gap in Tunisia.

4.4 Findings on Personal Use of ICT

The survey on the extent of usage of ICT by teachers revealed 42% of respondents agreeing to the fact that they used computers more in their place of work rather than at home. 58% of them operated the computers both at home and at work. Questions were also administered

Opinion Frequency Percentage (%) Indifferent 3 3.7 Favourable 44 54.3 Unfavourable 34 42 Total 81 100


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about the number of internet connections in a week and the frequency of email usage. A consistent response was reported on the frequency of email usage and internet browsing a week. This validates the fact that the internet was connected for the sole purpose of sending mails. This proves that the teachers have not taken their initiative for self advancement and there is a non existence of ICT based homework. In terms of the mode of training received in relation to the use of ICT a diverse profile emerged from the sample. Several modes of training such as routine training, specific training, self study and help from colleagues and friends were put forth for choosing. The results obtained for this question is shown in Table 6. Table 6: Mode of Training

Mode Frequency Percentage (%) Undergone Routine Training 18 22.2

Undergone a specific training 13 16.0 Self study 24 29.6 Colleagues and friends 26 32.1 Total 81 100

Table 6 shows that 22.2% of the teachers gradually got acquainted with the ICT in their routine training period, 32.1% of the teachers confessed that they were trained by their colleagues while 29.6% underwent a self study. A startling percentage of 96.3% invalidated the act of participating in a training course that focussed specifically on the educational use of ICT. This clearly evidences the fact that there is absolutely no impetus from the part of the institution to enhance ICT skills. The respondents were also given an option to rate their awareness in ICT and 14.8% of the respondents assessed themselves as beginners and 37% of them marked themselves as average with respect to the use of communications environment (that is the usage of internet, emails etc). 9.9% of the teachers rated themselves as excellent and 2.2% expressed total unfamiliarity with the ICT. With regards to the usage of standard software like word, excel etc 11.1% the respondents rated themselves as experts. This shows that the majority teachers met the minimum criteria in order to satisfy the requirements of achieving a threshold in computer literacy. Empowering them and initiating changes would bring phenomenal changes in the usage of ICT. 4.5 Findings on the personal attitude towards ICT

The questionnaire finally concluded with questions relating the personal opinion of teachers regarding their approach to the current use of ICT in their institutions. Various questions were put forth relating to the different fields in which ICT was being implemented from an individual purview. The results of the answers received from these questions are summarised in Table 7.


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Table 7: Results Summary of Responses from Teachers (Usage of ICT)

Strongly disagree

(%)

Disagree

(%)

Agree

(%)

Strongly Agree (%)

I like to use the computer to prepare course materials. 6.2 25.9 43.2 24.7

I found that using the Internet facilitates the realization of my lesson plans. 9.9 34.6 30.9 24.7

When I am in class, the computer is part of my routine teaching tool. 22.2 51.9 19.8 6.2

The computer is essentially a means of communication (electronic mail). 3.7 23.5 59.3 13.6

The computer is essentially a means of distraction 12.3 66.7 19.8 1.2

The computer is essentially an instrument of work outside the classroom context (information retrieval, preparation of course).

3.7 24.7 51.9 19.8

The use of ICT in education is justified in institutions in science or technology and not in other institutions.

61.7 35.8 0 2.5

The survey on the attitude to ICT in education attained positive responses. According to survey results, we note that 67.9% of teachers surveyed agreed on the preparation of materials for teaching using the computer. However, only 55.6% said that surfing the Internet facilitated the preparation of the course. In addition 74.1% of teachers surveyed said that IT did not occupy a part of their everyday teaching tool. The computer was essentially a communication medium for 72.9% of subjects and did not pose as a means of distraction for 79% of teachers. It also served as an instrument of work outside the class for 71.7% of respondents. Finally, almost all respondents admitted that the use of ICT cannot be justified only in science-based institutions. These results arrived at the fact that ICT was only utilised for sending emails which in turn reaffirmed its stand as a communication tool. The Wilks’ lambda test proved that the effect of gender, age, rank and experience of the teachers, were not related to the usage of ICT. The discriminating variables were "number of Internet connections per week", "number of email use by week," "learning mode", "the use of communications software" and "the use of common software". Thus we can conclude that the differences among instructors arise due to the differences in the method of using ICT. 5. CONCLUSIONS AND RECOMMENDATIONS The purpose of this research was to explain the causes of digital divide in the academic institutions in developing countries using Tunisia as a case study. Our main objective was to clarify if it is due to a problem of access or use of ICT. A survey was conducted among a sample of 100 instructors from the Sfax University with a response rate of 81 percent.


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It follows from this survey that the majority of instructors have developed a minimum level of skills to use computers. Regardless of academic rank, they meet the criteria defining the functional computer literacy, so they are able to use common office software (Word, Excel and PowerPoint) and to use the Internet (surfing and communicating). Moreover, the majority of these instructors were self trained or trained by colleagues and few received professional training. Therefore, we can conclude that providing adequate training programs can upgrade the level of integration of ICT in education. The study showed that most respondents had a computer, both at home and at work and were mainly users of office software. They generally used multimedia technology (e-mail or Internet) for private purpose and for widening access to sources of information for their respective course. Regardless of the gender, age, rank and experience of the teachers, we found significant differences in relation with the use of ICT in teaching. The discriminating variables were "number of Internet connections per week", "number of email use by week," "learning mode", "the use of communications software" and "the use of common software". Thus, we can conclude that the differences among instructors arise due to the differences in ICT usage. The Tunisian government provided sufficient infrastructure and an environment conducive for the integration of ICT in education. However there is a strong trend towards the establishment of E-education. Consequently, it is a question of willingness from the instructors to successfully integrate these new technologies in the education process. The effectiveness of these technologies depended primarily on ability and willingness of stakeholders in the academic field. In this sense, the emphasis here is on human capital. So we can conclude that these problems are with the use of ICT rather than access. Finally, we argue that emphasis should be provided on training the faculty for updating them with the latest technology used in institutions. A strategic alliance with technological experts can prove beneficial for the institutions as they can benefit from the expertise provided by the companies who are adept in latest technological developments. A new curriculum encompassing the imperativeness of the application of ICT in routine teaching can be framed. Policies can be implemented which necessitates the adoption of ICT by institutions in order to attain ministry recognition. Limitations arise in this study due to the limited time period and sample used in this research. Therefore suggestions for future research centres around the adoption of a longer time period and larger sample. This paper which used Tunisia as a case study can be replicated in the educational environment of other developing countries in order to examine the existence of digital gap and the major factors contributing to this gap in these countries and to see whether they face similar issues concerning ICT.


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6. REFERENCES

[1] Baile, S. and Lefievre, V. (2003). "The successful use of email - a study of its determinants within a production unit of aircraft maker", 8th conference of AIM, Grenoble.

[2] Bloom, B S. (1968). Learning for mastery, Evaluation Comment. (UCLA-CSIEP), 1(2), 1-12.

[3] Charfi, A. (2004). "Attitudes of teachers’ vis-à-vis ICT", Working Paper, FSEG Sfax-TUNISIA.

[4] Gurova, E. (2001). "The Digital Divide - A Research perspective.” Seville, IPTS. [5] Komis, V. (2001). "The information technology and communications in the Greek

educational system: the difficult path of integration," Journal of Education and Public Information, No. 101.

[6] Larose, F. (1999). "The information technology and communication in university teaching and training teachers: Myths and Realities," Journal of Science Education: Perspectives of Future Education, Volume 27, No. 1

[7] Lebrun, M. (2002). "Theories and methods for teaching and learning: Which place for ICT in Education", De Boeck, Bruxelles-Paris.

[8] Looker, D. & Thiessen, V. (2003). "The digital divide in Canadian schools: factors that affect access to information technologies and their use by students", Working Paper, No. 81-597 -XIE.

[9] Makrakis, V. (1988). Computers in Education, Studies in International and Comparative Education, Stockholm International Education.

[10] Reddick, A., Boucher and C., Groseilliers, M. (2000). "The Dual Digital Divide: The Information Highway in Canada", Public Interest Advocacy Center, Ottawa.

[11] Renaud, P and Torres, A. (1996). "lnternet, a chance for the South", Diplomatic World, p 6.


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A COMPARISON OF GENERAL DESIGN AND LOAD REQUIREMENTS IN BUILDING CODES IN

CANADA AND SYRIA

Samer Al-Martini* College of Engineering and Computer Science,

Department of Civil Engineering, Abu Dhabi University, Abu Dhabi, UAE

ABSTRACT: This paper aims at comparing the Syrian and Canadian codes used for design and execution of reinforced concrete building structures. Primarily, the Arabic Syrian Code for Design and Execution of Reinforced Building Structures, 2004 (ASC, 04) has been studied and compared with both the National Building Code of Canada (NBCC) for loads specification and the Canadian Standard Association Code (CSA A23.3) for reinforced concrete specification. The study revealed that the Syrian code has increased the “factor of safety” by recommending higher values of load factors where, the factored dead load and the live load are almost 20% less in Canadian code than that in Syrian code due the difference in the dead and the live loads magnification factors. KEYWORDS: building codes, load factors, factored resistance, live load demand, nominal resistance

1. INTRODUCTION

The Arabic Syrian Code for Design and Execution of Reinforced Building Structures (ASC) [1] is adopted in Syria for designing a building. In Canada, the National Building Code of Canada (NBCC A23.3-04) [2] for loads specification and the Canadian Standard Association Code (CSA A23.3) [3] for reinforced concrete specification are used for designing buildings. The Syrian and Canadian codes share the basic rationale, and have many common features. They contain general requirements for safety, serviceability, and structural integrity. It may be worth presenting a brief historical review of both codes and how they were developed and modified over years. The constitution in Canada gives each province the responsibility for setting its own building construction regulation. In a few cases the provinces have given the municipalities the historic right of writing their own building codes. As such, in the early years, regulating building construction in Canada was done by patch working of building codes across Canada. The National Building Code in Canada was first published in 1941 by the federal government. This code was later adopted by the various provinces and municipalities in Canada during the next 20 years. Since 1960, The National Building Code of Canada has been revised about every five years up to 1995. However, the 2000 edition of the building code was taken considerably longer time than what was expected and the next edition of the National Building Code of Canada was published in 2005. The available 2005 edition of the National Building Code of Canada (NBC) has over 800 technical changes. The 2010 National Building of Canada Codes was published on November 29, 2010.


_____________________________* Corresponding Author.E-mail : [email protected]

20 212

The Syrian code has been modified over time as well. The second edition of the Syrian code was issued in 1995 and then was followed up with three appendices in 1996, 1997, and 2000; these appendices provided specifications for building design against earthquake. The second edition along with its appendices has provided the Syrian civil engineers with the necessary aids required for designing anti-seismic structures. However, during implementing the second edition of the code, it was realized that the code needs to be modified in order to account for the rapid advancement in computer technology and the continuous development of structural software. Moreover, it has become necessary that the code covers steel structures as well. Therefore, the third edition of the code was published in 2004 along with 14 appendices to account for the abovementioned aspects.

2. COMPARISON BETWEEN THE SYRIAN AND CANADIAN CODES

2.1 Structural Load Specifications

Dead Loads This term includes the weight of the member itself, and the weight of all members permanently supported on this member such as partitions and appliances. Partition loads used in the design shall be shown on the drawings. The calculation of the dead load in both codes follow similar concepts taking into consideration the type of material used in each case with its unit weight. The basic difference between the two codes is in the magnification factor used for the dead loads. In the ACS the dead load is multiplied by a factor of 1.5 while it is multiplied by 1.25 in the NBCC. Live Loads The live loads on an area of floor or roof depend on the intended use of the particular structure. Table 1 shows a comparison between the uniformly distributed load patterns taken from Table 5.2 and Table 4.1.5.3 in Syrian and Canadian Codes [1,2], respectively. Table 1- Live loads specification in ASC and NBCC codes Codes bedrooms (KPa) Stairs (KPa) Roofs (KPa) LL Reduction Factors

ASC 2 3 1 1.8 NBCC 1.9 1.9 1 1.5

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20 213

Snow Loads In the ASC the snow load is taken considering the elevation from the sea level [1]. The ASC would require that snow load on a roof of an ordinary building in Damascus region to be taken as 1 KPa [1]. In NBCC the snow load on a roof is determined considering the product of a ground snow load (determined from a map) over 30 years and a ground to-roof conversion factor [2]. The NBBC would require that the roof of an ordinary building to be designed for a snow load of 2 KPa. The difference between the two values is a logical reflection of the difference in weather conditions between the two regions. Wind Loads In the ASC the pressure exerted by the wind on an ordinary building with low height

⎟⎠⎞

⎜⎝⎛ < 4

widthheight is taken only as a static horizontal uniformly distributed load according to the

following equation: qkCCP sep= (KPa) (1) Where, Cp is the sum of the pressure coefficients related to the surface roughness and number and its values is taken from Table 5.5 from the ASC [1]. Ce is a coefficient related to building height from the ground surface. This factor accounts for the increase in the wind velocity with height. It is calculated according to the following

equation: 60

421+

−=h

Ce (2)

ks is a coefficient related to the location of the building in terms of its exposure to wind and it is taken from Table 5.6 in the code. q is the reference velocity pressure in KPa, and it is defined as the pressure due to wind excreted on a flat plate suspended at 10 m above the ground surface. It is calculated according to the following equation:

1630/2Vq = (3) Where, V is average wind velocity (m/s) In the NBCC the wind load is calculated according to the following equation:

pge CCqCp = (4) Where, q is calculated according to the following equation:

25.0 Vq ρ= (5) Where, ρ is the air density during the windy period of the year and its values are tabulated in Appendix C2-12 of NBBC [2], V is hourly average wind velocity.

A COMPARISON OF GENERAL DESIGN AND LOAD REQUIREMENTS IN BUILDING CODES IN CANADA AND SYRIA

22 234

Ce is the exposure facto and it is. It is calculated according to the following equation:

2.0

10⎟⎠⎞

⎜⎝⎛= i

eh

C (6)

Cg is the gust factor; it accounts that when gusts blow they may have velocity greater than that of wind. In the simplified method, this term is taken as 2 for the design of building as whole. It should be noted that this term is not considered in the ASC for the calculation of loads due to wind. Cp is the external pressure coefficient. This factor is given in Commentary B2-17 of the NBCC for various shaped building [2]. Load and General Design Requirements for Canadian and Syrian Codes The load requirements in both codes are similar in their rationale but different in their specifics. The load combination in the ASC is calculated according to the following equation: U = 1.5DL+ 1.8LL (7) In the NBCC the ultimate load is calculated according to the following equation: U = 1.25DL + 1.5LL (8) Where, DL refers dead loads and LL refers to live loads. 2.2 Structural design specifications Flexural Design of a beam Both codes i.e, ASC and CSA A23.3, follow the ultimate limit state philosophy for designing flexural members. In the ASC code the maximum strain of concrete (έcu) in stress block (Fig. 1) is 0.003 , while it is taken equal to 0.0035 in the CSA A23.3. Moreover, the stress in stress block is taken as 0.85f’c in the ASC and it is taken as α1f’c in the CSA A23.3. In the ASC the stress block depth (a) is: a=0.85C (9) In the CSA A23.3 the depth of stress block is calculated using the following equation: a=ß1C (10) Where, C is the depth of neutral axis ß1 = 0.97-0.0025f’c ≥ 0.67 (11) Figure 1- Stress block for a beam

H

b

a

εs ≥ εy

C

Axis of zero strain d

έcu 0.85f’c

As fy

SAMER AL-MARTINI

22 235

In the ASC the strength reduction factor Ω is used to account for the possible variations in dimensions of concrete section and placement of reinforcement and other miscellaneous workmanship items and it is equal to 0.9, 0.7, and 0.85 for bending, axial compression, and shear and torsion, respectively. Thus, the reduced nominal flexural strength (Mr) is calculated according to the following equation:

⎟⎠⎞

⎜⎝⎛ −Ω=

2adfAM ysr , (Ω = 0.9) (12)

In the CSA A23.3, the factored concrete compressive strength used in checking ultimate state shall be taken as cc f 'φ (øc = 0.65) and the factored strength of steel reinforcement is øs = 0.85.

⎟⎠⎞

⎜⎝⎛ −=

2adfAM yssr φ , ( Φs = 0.85) (13)

Where, ⎟⎠⎞

⎜⎝⎛ −=

2adfAM ysn (14)

Shear design of a beam The shear due to the applied loads on a beam is usually calculated at a distance d from the inner face of the support in both codes CSA A23.3 and ASC. A simplified approach, in which the angle of shear cracks is considered to have a 45o with the horizontal line, is used in the ASC. In CSA A23.3 there are two methods namely the Simplified Method and the General Method. The Simplified Method is used for flexural members without significant axial tension. The basic design equation for shear capacity of slender concrete beams in both codes is: fr VV ≥ (15) Where, Vf is the shear force due to the factored loads and Vr is the factored shear resistance given by: Vr=Vc+Vs (16) Where, Vc is the shear carried by concrete and Vs is the shear carried by the stirrups. The shear carried by concrete (Vc) is calculated according to the following equations: In the ASC:

cwf

fwcc fdb

MdV

fV '3.018'16.0 ≤⎟⎟⎠

⎞⎜⎜⎝

⎛+= ρ (MPa) (17)

)( cf

yv

VVdfA

S−

= (18)

In the CSA A23.3:

dbM

dVfV w

f

fwcc ⎟

⎟⎠

⎞⎜⎜⎝

⎛+= ρ2.17'158.0 (MPa) (19)


24 256

Where, ρw is longitudinal steel reinforcement ratio, bw is width of web of member and Mf is applied moment at a section due to factored loads.

)( cf

yvs VV

dfAS

−= φ (20)

Where, S is stirrup spacing (mm), Av is area (mm2) of stirrup reinforcement within a distance s, and øs =0.85 is the resistance factor for reinforcing steel. Design of Columns The figure below shows a given strain distribution for a loaded column adopting the ASC . Figure 2- Stress block for a column in ASC In ASC, the strength of a column under truly axially loading is calculated as:

( )[ ]stystgcor AfAAfP +−Ω= '85.0 (21) Ω = 0.7 (axial load) Ag = gross area of the section (concrete + steel) fy = yield strength of reinforcement Ast = total area of reinforcement in the cross section To account for the un-expected moment, the code specify that the maximum load in column must not exceed:

ror PP 8.0max, = for tied column.

ror PP 85.0max, = for spiral column. The figure below shows a given strain distribution for a loaded column according to CSA A23.3: Figure 3- Stress block for a column in CSA A23.3

0.0035

ε'si

εsj

A’s

As

α1f’c

Asfs

A’sf’s

α1 A’cf’c

0.003

ε'si

εsj

A’s

As

0.85 f’c

Asfs

A’sf’s

0.85A’cf’c

SAMER AL-MARTINI

24 257

The strength of a column under truly axially loading is [4]:

( )[ ]stysstgccor AfAAfP φαφ +−= '1 (22) α1 f’c= maximum concrete stresses

cφ , sφ = material strength reduction factors To account for the un-expected moment, the code specifies that the maximum load in column must not exceed:

ror PP 8.0max, = for tied column.

ror PP 85.0max, = for spiral column. Thus, it can be observed that the differences between the two codes are in taking the maximum concrete stresses (stresses block) and in the material reduction strength. Design of slabs The thickness in ASC of a slab can be calculated from a table based on the type of a slab (one way or two ways) and its dimensions. For a regular building having LL ≤ 5KN/m2, the moment distribution on each slab can be calculated using one of the following methods: The Moment Distribution Factors Method, where the distribution factors on each slab spans are obtained from tables considering the location of each slab.

2waM Aa α= (23) Where, Ma is the moment on short span of slab, aA is moment distribution factor, w is factored load, and a is the short side dimension. The same equation is applied for the other span of the slab (long span) with different moment distribution factors and span dimension. The Strip Method considering interior or exterior support for negative and positive moment. The factored static moment of a rectangular slab can be calculated: 2

222 wLM o μ= (short span (L2)) (24) 211 oo MM μ= (long span (L1)) (25)

Where, µ1, µ2 are factors obtained from a table considering1

2

LL

=μ .

Negative moment and exterior support: ML1= 0.3Mo1, and ML2=0.3Mo2. Negative moment and interior support: ML1= 0.6Mo1, and ML2=0.6Mo2. Positive moment: ML1= 0.75Mo1, and ML2=0.75Mo2. Reinforcement is designed for the moment considering the section is rectangular. The thickness of a slab in CSA A23.3 is calculated using equations specified in the code for different cases. The Direct Design Method can be applied if the following conditions are satisfied [4]:

2≤spanshortspanlongMax (measured centre to centre of supports) .

The column offsets are less than 20% of the span.


26 278

There is a minimum of spans in each direction is three. The factored live load must not exceed two times the factored dead load. The total static moment for each slab is calculated using the following equation:

8

22 naf

o

llwM = (26)

Where, wf is factored load per unit area; ln is clear span between columns; and l2a is transverse width of strip. This moment is distributed on the beams and slab spans using factors given in a table provided by the code (CSA A23.3). It should be noted that reinforcement in both codes is designed for the moment considering the section as a rectangular beam. 3. SUMMARY AND CONCLUSIONS The paper attempted to investigate the differences in general design and load requirements in Building Codes in Canada and Syria used for the Design and Execution of Reinforced Concrete Building Structures. The Arabic Syrian Code for Design and Execution of Reinforced Building Structures (ASC) is used in Syria to design a building while, in Canada, the National Building Code of Canada (NBCC) for loads specification and the Canadian Standard Association Code (CSA A23.3) for reinforced concrete specification are used for designing a building. The paper showed that the Syrian code has increased the factor of safety by adopting higher values of load factors. Also, the live loads for rooms and stairs in the ASC are higher than that specified in NBCC. It can be argued that the ASC is more conservative than the NBCC which is likely due to the fact that Syria lies on an active seismic zone. 4. REFERENCES

[1] ASC, Arabic Syrian Code for Design and Execution of Reinforced Building Structures. (2004)

[2] NBCC, National Building Code of Canada. (2007) [3] CSA A23.3, Canadian Standard Association Code. (2003) [4] MacGregor, G. J., and Bartlett, F. M., Reinforced Concrete Mechanics and Design,

1st ed, Prentice Hall Canada Inc. (2000)

SAMER AL-MARTINI

26 27

ANALYSIS OF SOIL MEDIA CONTAINING CAVITIES OR TUNNELS BY THE BOUNDARY ELEMENT METHOD

Omar al-Farouk S. al – Damluji1, Mohammed Y. Fattah*2

Rana A. J. al-Adthami3

1. Former Professor, Civil Eng. Dept., College of Eng., University of Baghdad, Iraq. 2. Assistant Professor, Building and Construction Engineering Department, University of Technology,

Baghdad, Iraq. 3. Former graduate student, Civil Eng. Dept., College of Eng., University of Baghdad, Iraq

ABSTRACT: In the design of tunnels to be constructed in urban areas, it is necessary to estimate the magnitude and distribution of the stresses and settlements that are likely to occur due to a particular design and construction technique. The main factors that greatly affect the stresses and deformations around tunnels and underground excavations are the shape, dimensions, depth of opening below the ground surface, distance between the openings and the kind of supports.

In this paper, a study of the effect of different parameters was conducted by considering a cavity of 4 meters diameter under a constant surcharge load of 50 kN/m2. These parameters are: 1. depth below the ground surface Zo, 2. eccentricity of a cavity locations from the centerline of surface loading, and, 3. distance between cavities K.

A computer program for analysis by the boundary element method is used for the determination of the stress and deformation fields around two cavities with the above mentioned parameters. The soil is assumed to be homogeneous, isotropic and a linearly elastic medium containing two openings.

It was found that a marked increase of stresses takes place as the cavity approaches the ground surface and the stress distribution is very sensitive to the depth variation compared with the case of no-cavity condition. The maximum stresses occur at the haunches of the tunnel rather than at the crown. The vertical displacement of the soil medium increases by decreasing the distance between the adjacent openings. In general, small values of K/D ratios (where K is the distance between two cavities and D is the diameter of one cavity) should be avoided to hinder rapid increases in the stress concentration. KEYWORDS: Boundary element, Soil, Cavity, Tunnel. C 1. INTRODUCTION The boundary element method (BEM) has become one of the most powerful tools for the numerical study of different engineering problems. The comparison of the main features of this method with those of the finite element method (FEM) has occupied many pages in the specialist literature sine the initial development of BEM. An important feature of the BEM is that the functions that represent essential and natural boundary conditions (potential and flux in potential theory and displacements and stresses in elasticity theory) which are the basis of the method, consequently being approximated in an independent form, their coordinates remaining as independent variables of the formulation. In spite of non-symmetric and fully populated character of the matrices associated to BEM, it must be pointed out that the size of the system of equations, defined by the stiffness matrix K, is always smaller than in the finite element method (FEM) approach, for a similar


__________________________* Corresponding Author.E-mail : [email protected]

28 29

degree of dicretization. The ratio between the sizes of the matrices in the two methods will depend on the geometry under consideration, and in particular on the proportion of the boundary (area in 3D and length in 2D problems) to the domain (volume in 3D and area in 2D problems). The smaller this proportion (the greater the domain covered by a certain boundary), the greater the ratio between the size of the matrices of FEM and BEM (the more favourable the use of BEM), [4]. 2. ANALYSIS USING THE BOUNDARY ELEMENT METHOD Although the finite element techniques have been used in so many practical problems, the boundary formulations appear as an alternative technique that, in many cases, can provide more reliable or economical analysis. Even with automatic mesh generation techniques, the finite element method has not found widespread application to tunneling problems because of the data preparation problems and considerable computer time requirements. The input data requirements of the boundary element method are considerably less than these of the finite element method since only the boundary need to be discretized. Unlike the FEM, the BEM can model the boundaries at infinity without truncating the outer boundary at some arbitrary distance from the region of interest.

After the numerical treatment of the integral equations, we end up with a system of equations. In contrast to the FEM, the coefficient matrix is fully populated and unsymmetrical. Standard Gauss elimination can be used but, for large systems, the storage requirement and the computation times may be reduced considerably by iterative solvers, such as conjugate gradient methods. Here we also find that the method is “embarrassingly parallelisable” i.e. that excellent speed up rates can be achieved with special hardware. The primary results obtained from the analysis are values of displacement or traction at the boundary depending on the boundary condition specified. In contrast to the FEM, primary results do not include values in the interior of the domain but these are computed by post-processing, [2]. 2.1 Boundary Element Equations Isotropic field problems have a governing equation. From the mathematical analysis, the corresponding boundary integral equation with respect to a source point (xi, yi), can be written as follows (Brebbia, 1978):

∫∫ΓΓ

+Γ=Γ+ i**

ii bdquduquC (1)

where: Ci is a constant depending on the location of the point within the domain Ω, ui = u(xi, yi)

and ∫∫Ω

−−φ== dxdy)yy,xx(u)y,x()y,x(bb ii*

iii (2)

If the piecewise-discretization concept, which is usually used in finite element analysis, is applied here, then the boundary Γ may be divided into a number ne of sub-boundaries, connected by boundary points, as shown in Figure (1).

OMAR AL-FAROUK S. AL-DAMLUJI, DR. MOHAMMED Y. FATTAH, RANA A.J. AL-ADTHAMI

28 29

Figure (1) – Boundary discretization.

If f (x, y) is a continuous function defined over Γ, then it can be deduced that:

∫ ∑ ∫Γ = Γ ⎥

⎥⎦

⎤

⎢⎢⎣

⎡Γ=Γ

e

e

n

1edfdf (3)

Applying the boundary-discretization concept, then equation (1) can be rewritten in the following form:

i

n

1eeii

*n

1eeii

*ii bd)(q)yy,xx(ud)(u)yy,xx(quC

e

e

e

e+

⎥⎥⎦

⎤

⎢⎢⎣

⎡ΓΓ−−=

⎥⎥⎦

⎤

⎢⎢⎣

⎡ΓΓ−−+ ∑ ∫∑ ∫

= Γ= Γ (4)

where u (Γe) and q (Γe) may be approximated by means of interpolation expressions in terms of their values at source boundary nodes.

Using such a discretization technique, it is possible to represent a boundary integral equation by means of a simple algebraic equation in terms of the boundary nodal values of field function parameters. Full description of the boundary element formulation is found in El-Zafarany [4], Paris and Canas [5] and Al-Adthami, [1]. All explicit expressions for the fundamental solution parameters given here are found in Al-Adthami, [1]. 2.2 Computer Program A computer program based upon the theory of the two-dimensional solid continuum mechanics problems of the boundary element method with constant elements is coded in FORTRAN 77 and introduced herein. The program can deal with plane stress and plane strain problems with surface and domain loadings. 3. CASE OF TWO CAVITIES Figure (2) shows a schematic representation of the problem to be studied for four values of depth/diameter ratios (Zo/D = 1, 1.5, 2 and ∞). The origin of coordinates (X and Y) is considered at the center of the ground surface.

......

. . . ..Ω

Γ

Γe

Y

X

Nodes

Element


30 31

Figures (3) and (4) show the distribution of vertical and horizontal stresses along the centerline of the surface loading (line I-I in Figure 2). The stresses in these figures are normalized by dividing each stress by the initial overburden stress (P).

It is obvious from these figures that the vertical stress distribution decreases with the increase of Zo/D ratio and the maximum value of horizontal stress decreases as Zo/D increases. It is also noticed that the values of (σy/P) and (σx/P) become constant at a depth of (Y/D = 5). Therefore, the depth in the figures is restricted to five diameters only.

Figures (5) and (6) show the horizontal and vertical stress distributions along a horizontal line 1.0 m below the ground surface (line II-II in Figure 2). These figures indicate that there is a big disturbance in the stress distribution when Zo/D≤ 2 as the cavities approach the ground surface. It is also evident from these curves that the heave effect starts to appear at a distance equals to the tunnel diameter D away from the centerline of the surface loading. Figures (7) and (8) show the distribution of horizontal and vertical stresses along a line 7.0-meter away from the centerline of the load width, (line III-III in Figure 2). It is noticed that disturbance in the stress distribution extends to a depth of about (Y/D = 3). Below this depth, the stress distribution tends to be uniform.

Figures (9) and (10) show the contour lines for four values of Depth/Diameter ratios (namely, Zo/D = 1.0, 1.5, 2.0 and ∞). The contours are drawn for vertical displacement and vertical stress distributions, respectively. These figures reveal that the highest values of displacements and stresses concentrate in the space between the cavities. 4. INFLUENCE OF ECCENTRIC LOCATIONS OF CAVITIES Figure (11) shows a schematic representation of the problem to be studied for five values of eccentricity/diameter ratios (e/D = 0, 1, 2, 3 and ∞). Figure (12) shows the vertical displacement (Uy) distribution along the ground surface. It can be noticed from this figure that the effect of the cavity on the surface settlement must be taken into consideration if e/D < 3 and neglected otherwise. This figure also provides designers with some guidance regarding the influence of the cavity location on the settlement of the ground surface.

Figure (13) shows the vertical stress distribution over a line 3 meters below the ground surface (line IV - IV in Figure 11). From this figure, it is noticed that when the cavity is about 4.0 m away horizontally from the centerline of the surface loading (e/D = 1), σy on this line increases by about 5% from the case of no-cavity under the center of the surface loading. While for other values of e/D ratio, σy decreases. Also, heave stresses appear on the area above the cavity on this line.

Figures (14) and (15) illustrate the variation of σy and σx on the centerline of the surface loading. The effect of the cavity can be neglected in computing the stress values on this line when e/D<3. Furthermore, it is easy to notice from these figures that the concentric cavity has a great influence on the disturbance of stresses over this line. It decreases the vertical stresses and increases the horizontal stresses significantly.


30 31

Figure (16) shows the variation of vertical displacement over a line 1 m below the ground surface (line II-II in Figure 11). It is evident from this figure that the concentric location (e/D = 0.0) of the cavity is the critical location which results the largest displacement on this line. Also, with the increase of e/D ratio, the settlement decreases.

.

Figu

re (2

)-Sc

hem

atic

vie

ws o

f sur

face

load

-soi

l-cav

ities

syst

em.

III

D =

4 m

D =

4 m

K=

4 m

4 m

6 m

8 m

24 m

24 m

24 m

II

III

II

B=

4 m

P= 5

0 kN

/m2

7

m

II

1 m


32 33

σy/P

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

0 0.2 0.4 0.6 0.8 1 1.2

Zo/D=1.0Zo/D=1.5Zo/D=2.0Zo/D=∞

Y/D

σx/p

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

-0.2 -0.1 0 0.1 0.2 0.3 0.4

Zo/D=1.0Zo/D=1.5Zo/D=2.0Zo/D=

Y/D

∞

Figure (3) -Vertical stress distributions along line I-I.

Figure (4) - Horizontal stress distribution along line I-I.

Figure (5)-Variation of horizontal stresses along line (II-II).

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0 1 2 3 4 5

Z o /D = 1 .0Z o /D = 1 .5Z o /D = 2 .0Z o /D =

X/D

σx/p

∞


32 33

σx/P

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

-0.1 -0.05 0 0.05 0.1 0.15 0.2


Y/D

∞

σY/P

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 0.05 0.1 0.15 0.2 0.25


Y/D

∞

Figure (6)-Variation of vertical stresses along line II-II.

Figure (7)-Horizontal stress distribution along line (III-III).

Figure (8)-Vertical stress distribution along line (III-III).

X/D

-0.25

0

0.25

0.5

0.75

1

0 1 2 3 4


σ y/P

∞


34 35

Elev

atio

n (m

)

Distance (m) (a)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124

Elev

atio

n (m

)

Distance (m) (b)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124

Elev

atio

n (m

)

Distance (m) (c)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124

Elev

atio

n (m

)

Distance (m) (d)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124


34 35

Distance (m) (a)

Elev

atio

n (m

)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124

Distance (m) (b)

Elev

atio

n (m

)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124

Elev

atio

n (m

)

Distance (m) (c)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124

Distance (m) (d)

Elev

atio

n (m

)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124


36 37

The vertical stress distributions over a horizontal line passing through the centers of the cavities (line III-III in Figure 11) are illustrated in Figure (17). Over these lines, there is a rapid increase of the vertical stress at the points adjacent to the cavity. Also, σy is higher when the cavity is centered directly under the surface loading. However, it can be noticed from this figure that the variation of e/D ratio has a little effect on the state of stress over this line, except for the region adjacent to the cavity.

I

24 m

24 m

24 m

e =

4 m

e =

8 m

e =

12 m

P= 5

0 kN

/m2

4 m

Z o =

8 m

IV II

II

I

1

m

Figu

re (1

1)-S

chem

atic

vie

ws o

f sur

face

load

– so

il –

cavi

ty sy

stem

-

horiz

onta

l ecc

entri

city

from

load

cen

terli

ne.

I

3m

II

I

II

IV


36 37

Figure (12)-Vertical displacements on the surface.

Figure (13)-Variation of vertical stresses along line IV-IV.

Figures (18) and (19) show the contour lines for four values of eccentricity/Diameter

ratios (namely, e/D = 0.0, 1.0, 2.0 and ∞). The contours are drawn for vertical displacement and vertical stress distributions, respectively. It can be noticed that when (e/D ≥ 2), the effect of eccentricity of cavity vanishes.

Uy (

m)

0.00000.00020.0004

0.00060.00080.00100.00120.0014

0.00160.00180.0020

-5 -4 -3 -2 -1 0 1 2 3 4 5

e/D=0e/D=1e/D=2e/D=3e/D=

X/D

∞

0.000.050.100.150.200.250.300.350.400.450.50

-5 -4 -3 -2 -1 0 1 2 3 4 5


X/D

σ y/P

∞


38 39

σx/P

Y/D

∞

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

-0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5

e/D=0e/D=1e/D=2e/D=3

∞ e/D=

5. INFLUENCE OF DISTANCE BETWEEN CAVITIES “K” Figure (20) shows a schematic representation of the problem to be studied for five different values of K/D ratios (K/D= 0.5, 1, 2, 3 and ∞), where K is the distance between two cavities.

The settlement curves of the ground surface loading–soil-cavities system are shown in Figure (21). From this figure, it is evident that the surface disturbances due to cavity presence can be neglected at a distance exceeding 3D away from the centerline of the surface loading. Also, it can be noticed that as the distance K increases, the surface settlement decreases. For K ≥ 3D, the effect of the two cavities on the surface settlement can be neglected. The horizontal displacement on the ground surface is shown in Figure (22).

Figure (14)-Variation of vertical stresses along line I-I.

Figure (15)-Variation of horizontal stresses along line I-I.

σy/P

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 0.2 0.4 0.6 0.8 1

e/D = 0e/D = 1e/D = 2e/D = 3e/D =

∞

Y/D

∞


38 39

Figure (16) – Variation of vertical displacements along line II-II.

Figure (17)-Vertical stress distribution along the horizontal axis of cavities.

Figures (23) and (24) show the horizontal and vertical stress distributions along the

centerline of the surface loading (line I-I in Figure 24). It can be noticed from these figures that decreasing the distance K results in an increase in both σx and σy along this line.

0.00000.00020.00040.00060.00080.00100.00120.00140.00160.0018

-25 -20 -15 -10 -5 0 5 10 15 20 25


X (m)

Uy (m

)

∞

0.00.10.10.20.20.30.30.40.40.50.5

-5 -4 -3 -2 -1 0 1 2 3 4 5


X/D

σ y/P

∞


40 41

Figure (25) shows the vertical stress distribution along a line passing through the horizontal centerline of the cavities (line II-II in Figure 20). It is evident from this figure that the vertical stress increases by decreasing the distance between the adjacent cavities. Also, it is noticed that the stress concentration at the region between cavities centers decreases by increasing the distance “K”.

Figure (26) shows the horizontal stresses distribution along a line passing through the horizontal centerline of the cavities (line II-II in Figure 20). It is noticed from this figure that the horizontal stress decreases by increasing the distance between cavities.

Figure (27) shows the vertical stress distribution over a line 5.0 m below the ground surface (line III-III in Figure 20). It can be noticed that by decreasing the distance “K”, a big disturbance in the vertical stress occurs.

Figure (28) shows the horizontal stress distribution over a line 5 meters below the ground surface (line III-III in Figure 20). It can be noticed that by increasing the distance between cavities, there is a little disturbance in σx.

Figures (29) and (30) show the contour lines for four values of distance/diameter ratios (namely, K/D = 0.5, 1.0, 2.0, and ∞ ). The contours are drawn for vertical displacement and vertical stress distributions, respectively.

It can be noticed that when (K/D = 1.0), the maximum displacements and stresses take place along the centerline of the problem.

Distance (m) (a)

Elev

atio

n (m

)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124

Distance (m) (b)

Elev

atio

n (m

)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124


40 41

Distance (m) (b)

Elev

atio

n (m

)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124

Figure (18) -Variation of vertical displacements in (mm) for: (a) e/D = 0, (b) e/D = 1, (c) e/D = 2 and (d) e/D = ∞.

Distance (m) (c)

Elev

atio

n (m

)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124

Distance (m) (d)

Elev

atio

n (m

)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124

Distance (m) (a)

Elev

atio

n (m

)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124


42 43

Figure (19) -Variation of vertical stresses in (kN/m2×10) for:

(a) e/D = 0, (b) e/D = 1, (c) e/D = 2 and (d) e/D = ∞.

Distance (m) (c)

Elev

atio

n (m

)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124

Distance (m) (d)

Elev

atio

n (m

)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124


42 43

6. CONCLUSIONS

From the previous work, the following conclusions have been reached: 1. A marked increase of stresses is found as the cavity approaches the ground surface and the

stress distribution is very sensitive to the depth variation compared with the case of no-cavity conditions.

Figu

re (2

0) –

Sch

emat

ic v

iew

s of s

urfa

ce lo

adin

g –

soil

– ca

vitie

s sys

tem

.

II

I

III

24 m

24 m

24 m

II

III

P= 5

0 kN

/m2

B=

4 m

2

4 m 8

1

2 m

Z o=

8 6

m


44 45

2. The maximum stresses occur at the haunches of the tunnel rather than at the crown. 3. For the circular cavity that is considered in this work, with increasing the depth below the

ground surface (Zo/D > 3), the surface settlements do not exceed 6 % from those obtained for the case of no-cavity condition.

4. The vertical displacement of the soil medium increases by decreasing the distance between the adjacent openings.

5. In general, small values of K/D ratios (where K is the distance between two cavities and D is the diameter of one cavity) should be avoided to hinder rapid increases in the stress concentration.

6. The region between the two adjacent cavities is more influenced by the distance “K” variation than the outer regions.

Figure (21)-Vertical displacements on the ground surface.

Figure (22)- Horizontal displacements on the ground surface.

0.00000

0.00005

0.00010

0.00015

0.00020

0.00025

0.00030

0.00035

0 5 10 15 20

X (m)

Ux

(m)

K/D=0.5K/D=1.0K/D=2.0K/D=3.0K/D= ∞

0.0000

0.0002

0.0004

0.0006

0.0008

0.0010

0.0012

0.0014

0.0016

0.0018

0.0020

0 5 10 15 20X (m)

Uy

(m)

K/D=0.5K/D=1.0K/D=2.0K/D=3.0K/D= ∞


44 45

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0.0 0.2 0.4 0.6 0.8 1.0

Y/D

K/D=0.5K/D=1.0K/D=2.0K/D=3.0K/D=

σy/P

∞

σx/P

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

-0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5

Y/D

K/D=0.5K/D=1.0K/D=2.0K/D=3.0K/D=∞

σx/P

7. REFERENCES:

[1] Al-Adthami, R. A. J., (2003). “Applications of the Boundary Element Method to Soil Media Containing Cavities”, M.Sc. thesis, University of Baghdad.

[2] Beer, G., Smith, I. and Duencer, C., (2008). "The Boundary Element Method with Programming", Springer-Verlag Wien New York.

[3] Brebbia, C. A., (1978). "The Boundary Element Method for Engineers", Pentech Press, London.

[4] El-Zafrany, A., (1992), “Techniques of the Boundary Element Method”, Ellis Horwood, New York.

[5] Paris, F. and Canas, J., (1997). (Boundary Element Method-Fundamentals and Applications), Oxford University Press.

APPENDIX I

Figure (23)-Horizontal stress distribution Figure (24)-Vertical stress distribution along line I-I. along line I-I.


46 47

Figure (25)-Vertical stress distribution along line II-II.

Figure (26)-Horizontal stress distribution along line II-II.

σ y/P

0.0

0.10.2

0.3

0.4

0.50.6

0.7

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5X/D

K/D=0.5K/D=1.0K/D=2.0K/D=3.0K/D= ∞

X/D

-0.20

-0.15

-0.10

-0.05

0.00

0.05

0.10

0.15

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

K/D=0.5

K/D=1.0

K/D=2.0

K/D=3.0

K/D=

σ x/P

∞


46 47

Etle

vatio

n (m

)

Distance (m) (a)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124

Figure (27) – Vertical stress distribution along line III-III.

Figure (28) – Horizontal stress distribution along line III-III.

-0.10

-0.05

0.00

0.05

0.10

0.15

0.20

0.0 1.0 2.0 3.0 4.0

X/D

K /D =0.5K /D =1.0K /D =2.0K /D =3.0K /D =

σ x/P

∞

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

K/D=0.5K/D=1.0K/D=2.0K/D=3.0K/D= ∞

X/D

σ y/P


48 49

Elev

atio

n (m

)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124

Distance (m) (d)

Figure (29)-Variation of vertical displacements in (mm) for: (a) K/D = 0.5, (b) K/D = 1, (c) K/D = 2 and (d) K/D = ∞.

Distance (m) (b)

Elev

atio

n (m

)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124

Distance (m) (c)

Elev

atio

n (m

)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124


48 49

Figure (30)-Variation of vertical stresses in (kN/m2×10) for: (a) K/D = 0.5, (b) K/D = 1, (c) K/D = 2 and (d) K/D = ∞.

Elev

atio

n (m

)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124

Distance (m) (a)

Distance (m) (b)

Elev

atio

n (m

)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124

Distance (m) (c)

Elev

atio

n (m

)

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 240369

1215182124

Elev

atio

n (m

)

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1215182124

Distance (m) (d)


50 51

GUIDELINES FOR IMPLEMENTING PIPELINE INTEGRITY TOWARDS MINIMIZATION OF HAZARDOUS ACCIDENTS

WITH PRACTICAL AND INDUSTRIAL CASE STUDIES M. El-Gammal (Sr.)1, H. El Naggar2*, M. M. El- Gammal (Jr.)1

1 Department of Naval Architecture and Marine Engineering, Faculty of Engineering, University of Alexandria, Egypt. 2 Civil Engineering Department, ALHOSN University, P.O. Box: 38722, Abu Dhabi, UAE. ABSTRACT: In a progressive environmentally conscious world gearing towards sustainability, pipeline designers, builders, and operators are faced with an escalating number of complex limitations and restrictions; all focused on increasing safety standards and reducing the risk of any potential pollution. The main objective of the current paper is to propose a new technique for risk estimation aiming at reducing bursting, explosions, fires, and corrosion of pipelines. Also, to demonstrate the new estimated risk concept by introducing analysis of various cases of pipeline accidents. So, the paper serves clearly in pipeline safety measures and pipelines integrity management. It is important to realize the meaning of pipeline integrity by managing safety as well as carrying out risk analysis through implementing the Asset Integrity Management (AIM) concepts. The pipeline problems could be definitely reduced as well as serving without non-expected or non-predicted hazards against loss in property, loss in lives, or loss of the pipeline itself.

This paper defines risk as applied to pipeline integrity by estimating the consequences which is being based on root cause analysis. The latter is found to depend on several surrounding and environmental factors. Practical examples from real industrial life problems have been investigated and demonstrated in views that the application of the root cause analysis, RCA, together with a scheme of AIM will reduce the recurrence of those accidents once the real cause has been known and properly maintained.

Keywords: pipeline, sustainability, Asset Integrity Management (AIM), Root Cause Analysis (RCA)

1. INTRODUCTION

Over the last few decades, the oil and gas industry has witnessed an unprecedented extensive development. Billions of dollars have been spent on construction of pipelines and infrastructure projects. Thus, quantifying the risk of potential problems associated with the operation of these infrastructures is of paramount importance for all stakeholders.

Traditionally, academicians used to teach their students only strength governed designs and facts of how to avoid catastrophic pipelines accidents. Nevertheless, in real practice due to the wrong practical treatment of the pipeline or by applying the wrong alternative solution offered and assumed within a design philosophy based on similar problems that may be far different from what safety seniors say [1-3]. Anyway one of the best advises the well experienced seniors in fields of pipelines, whom, used to recommend to their juniors that: “do not play with the pipeline, especially if it were containing flammable materials, such as gas and oil.” But instead juniors must be aware in prompt of how to deal with practical implementations of solutions. This is to be formulated through real gaining of practice as well as the well flow of information granted and collected from expert seniors of some of the vast remarkable theoretical and practical experience [4].

____________________________________________* Corresponding Author.Tel.: +971 2 4070529, E-mail : [email protected]


52 53

Recent pipeline accidents [5-10] show that there will be too much work needed to safeguard imminently our pipelines against fire, bursting and explosion hazards that will produce panic and thus the loss of property as well as resulting in the more expensive tragedy the loss of lives.

The intent of the present paper is to highlight reasons and causes of pipeline failures due to corrosion hazards. Furthermore to define the Root Cause Analysis “RCA” that must be based in turn on risk. The probabilistic approach that implies the calculations of consequences form contingent plans of safety through implementing the types of maintenance necessary to be carried out right in time. Deploring the monitoring and implying the quality auditing to promote reduction in downtime and to improve pipeline integrity as well as will deploying the lifetime at large will aim to reduce the leak before break and thus will reduce the risk of catastrophic explosion.

Definitely there will be no one unique solution to the problem of pipeline integrity and safety hazard prevention. But instead the designer ought to cover as much as he could from information from similar trouble shooting cases and then he could tailor the solution that definitely will reduce the risk. Yet this reliable solution again needs vast experience that some may be lacking. Thus the best solution and the better utilization of handling pipelines integrity problem shall be implemented and tabulated for any project while it is still in the paper stage. Alternative solutions must also be offered ready to be applied without trial and error but mathematically modeled and virtually implemented. The trial and error depends on luck more than engineering matters and technical assessments and thus, it will be waste of time as well as waste of money, waste of efforts and waste of property to apply that concept. So, it would be more reliable to rely on RCA applied in pipeline integrity, if the material, the environment, as well as the operators are all the same or nearly so.

2. DOES THE ASSET INTEGRITY OFFER THE BEST PIPELINE SOLUTION?

2.1 Definition and measures of integrity

Definition of the word “Asset” means evaluation, while the word “Integrity“ means unbroken completeness or totality [11]. That means in simple terms that Asset Integrity means the unity of evaluation for the wholeness of completeness. It is considered as the tool for management integrated solution offering the best of the better of choosing from the best design, better choice of materials and the better available manufacturing processes as well as the best assembly sequences and procedures for a pipeline. That is being assumed to be serving within an extreme aggressive environment. Thus it is a toolkit for reducing trouble shooting with better care to develop successful means to better managing the surrounding environment and better control of utilization of all production aspects in pipelines projects. This includes improving in the estimated lifecycle through better inspection intervals of monitoring. Thus this toolkit can give the management an overview leading to efficient evaluation of the project and reducing sudden catastrophic failures, by reducing the accidents in pipelines. Asset Integrity is anything of a value that incorporates owns that is held in firm adherence to a code.

M. EL-GAMMAL (Sr.), H.EI NAGGAR, M.M. EL-GAMMAL (Jr.)

52 53

2.2 Benefits and objectives from application of asset pipeline integrity in oil and gas fields:

In the oil, gas and power industries mitigating risk to Accidental Probablistic Risk Levels is not only vital to ensure compliance with legal requirements, but also reducing significant everyday losses:

• Improving safety alerts and environmental integrity through extending pipeline life cycle,

• Optimizing maintenance intervals and lower maintenance costs as well as less unplanned downtimes thus improving lifecycle and thus increrase productivity

• Reducing ligament thickness - metal loss due to corrosion deterioration and degradation problems,

• Machining slits (parent metal, seam weld, heat affected zone) defects can all be monitored and eliminated,

• Reducing the probability of fatigue cracks thus can control the sudden hazard events, • Identify and reduce hazards due to dents,dent/slit combination and mechanical damage

will also be under control.

2.3 How and why do Asset integrity being manipulated within the process of safety standards?

Asset Integrity is committed to prevent incidents that put people, neighbors, the environment and the facilities at risk. Therefore, asset integrity is the safety process which gives the decision maker the assurance that the facilities are well designed, safely operated and properly maintained, [12]. What is meant by Asset Integrity Approach and how it could be more useful in pipeline applications? Asset Integrity approach in pipelines integrity practical problems has been proposed from two or more decades [13-15] and denoted in Figures 1-a and 1-b. Figure 1-a gives the triangle of management decision success applied within asset integrity in fields of pipeline projects. It is based on root cause analysis which method can be applied to prevent the recurrence of the bad event in pipeline once again. Figure 1-b explains how the flow of information in the building up of correct decision is based on asset integrity, while Figures 1-c gives the different uses and the main pipeline applications now in current use. From that figure one can note the importance of maintaining pipelines. The figure as seen describes at its top the different types of pipelines currently applied. At the middle it demonstrates the different uses of pipelines in our wells, within different refineries’ departments, then to transportation facilities and ships to transfer oil, gas and their products using ships. The store tanks at the end of the transportation must be fitted also with pipes of different sizes, varieties in materials. All are to be serviced as terminal tanks for the end process of transportation. Then the feeding pipes to the industrial facilities are to be monitored to prevent environmental safety hazards. The last in the important cycle of pipelines harmony are those used to feed domestic uses in houses for warming, cooking and all other very important uses in the house hold equipment. The lower portion of Figure 1-c shows the different categories of pipelines in various


54 55

engineering fields of practice. Those figures are aimed at demonstrating the importance of risk based criteria.

Fig. 1-a: Asset integrity applied with RCA will lead to better utilization of pipeline [13-15]

Fig. 1-b: Pyramid of asset integrity the top is Asset Integrity at the base Safety of public interests and in between the inspection which means close supervision and proper maintenance

of a pipeline project.


54 55

Fig. 1-c: Practical and industrial uses of pipelines [16-19]

Figure 2 [23 & 24] shows the four steps for Risk Cost Identification and Assessment. From that figure that the first step in any model of pipeline risk assessment is being divided into several stages. The first stage is how to identify the cause and to recognize the hazard reason. The second stage is how to develop the risk assessment of that hazard if it were happened. The third stage in the model is how to devise a proper solution to control the hazard and its consequences. The fourth step is how to be able to estimate the cost of benefit associated with the involved savings of lives and properties against the determined risk. The fifth and final stage is how to demonstrate and to recommend a tailored decision for the management to take. Of course all steps are to be based on monitoring times, intervals and capabilities of the inspectors.


56 57

Generally the basic decision making is liable to bench marking and thus the success can be assessed by the use of KPI “Key Performance Indicator”. In case if there is alternative different solutions to deal with the same hazard then the KPI must be assessed for each alternative and by then the right measured value can give guidance to the management to decide which is the best alternative to be followed and thus which is being recommended.

Figure 2: Steps followed in Risk Identification [23]

3. RISK ANALYSIS IN PIPELINE INTEGRITY

Risk assessment provides a structured basis for pipeline operators to identify hazards and to ensure risks being ultimately reduced to appropriate levels in a cost-effective manner. The regulations applying to offshore operations in the pipelines’ industry require operators to undertake risk assessment in order to identify appropriate measures, as far as is reasonably practicable, to protect people against accidents. It may well be that the use of Quantitative Risk Assessment (QRA) for Temporary Refuges has given the impression that risk assessment is synonymous with QRA [22-24]. A risk assessment and management process that is focused on loss of containment of pressurized equipment in processing facilities, due to material deterioration is called by Risk Based Analysis [22]. These risks are managed primarily through equipment inspection. Root Cause Analysis ‘RCA” has two important roles in pipeline integrity management:

1. Identify Operational problem and issues

2. Identify consequences of a failure

2.1. Includes criticality –if equipment goes down, what are the effects on the system

2.2. Share consequences of past failures


56 57

Figure 3-a [22], shows the 6x6 ISO Risk Matrixes. As seen in this figure the likelihood of a bad event goes down starting at one for the lowest and goes to six at the utmost for the rare event. The six categories of probabilities of the event are two for the occasional, three for seldom, four for unlikely and five for remote. The impact and the consequences of the same event are defined by one for Catastrophic event, two for the severe, three for the minor, four the minor, five for the moderate and finally six for the incidental. Each will be having different values of weight factors as seen in the matrix. The weight starts with a value of unity for the likelihood and the catastrophic consequences and goes up to the value of 10 for the rare event and the incidental consequences. The ISO matrix as such is composed of 6 events x 6 impacts. Nevertheless, the ISO matrix can be reduced to be 5x5 matrix as shown in Figure 3-b.

1 Likely 6 5 4 3 2 1

2 Occasional 7 6 5 4 3 2

3 Seldom 8 7 6 5 4 3

4 Unlikely 9 8 7 6 5 4

5 Remote 10 9 8 7 6 5

6 Rare 10 10 9 8 7 6

6 5 4 3 2 1

Incidental Minor Moderate Major Severe Catastrophic

Decreasing Like

lihoo

d

Consequence IndicesDecreasing Consequence/Impact

3-a: 6x6 ISO Risk Matrixes

5 4 3 2 1

6 5 4 3 2

7 6 5 4 3

8 7 6 5 4

9 8 7 6 5

3-b: 5x5 ISO Risk Matrixes

Figure 3: ISO Risk Assessment Matrix [22]


58 59

4. STANDARD QUANTITAIVE RISK ASSET (SQRA)

As has been explained earlier that the calculated risk should be compared with a constraint value, named here by “Standard Quantitative Risk (SQR)”, to know whether the event is an expected, tolerated, predicted or a non-predicted one. Most of the Regulatory Bodies and Classification Societies have put forward risk motivation studies. In doing so, they have suggested constraint values quoted here as standard risk values. Yet those standard values can generally be applied to any of the pipeline integrity problems.

5. SUGGESTED TECHNIQUE FOR RISK ANALYSIS APPLIED WITHIN PIPELINES

The purpose of this work is to furnish a guidance of proposing a risk assessment method for pipelines through applying simpler techniques and methods leading to better end of risk assessment. The qualitative and semi-quantitative techniques have been applied to define standard risk values in accordance to the concerned Classification Society. It explains risk assessment technology as it might apply to pipeline operations, emphasizing techniques appropriate to pipeline hazards. Quality Risk Assessment “QRA” has a role in some pipeline applications, since it demonstrates how the wider range of techniques can help operators perform a suitable and sufficient risk assessment, and demonstrate that risks are As Low as Reasonably Practicable (ALARP) [22]. Figure 4 gives the flow diagram leading to the assessment of the integrated hazard in pipeline safety management.


58 59

Figure 4: Assessment of Integrated Hazard Identification in Pipeline Safety Decisions

The prediction criteria is such that if the estimated risk exceeds the standard value then the accident shall be considered as to be expected, but if the estimated value is less, the accident is said to be non-expected but happened.

Equation (1) is based on the two risk dividends. The first is known to be the frequency or the probability of the event. The second is known as the consequences and impacts from that event. Figure 5 highlights the sequence to be followed in the calculations of risk as shown by equation (1).


60 61

Risk = PE * TC (1)

Where,

PE is the frequency probability of the event E,

TC is the summation of consequences of the resulted impacts of that event as denoted by eq. (2).

The total impact of the consequences of an event is thus that denoted by equation (2) and Table I.

TC = LV + LP + S + E + Q + T + O + I (2)

where,

LV presents the panic due to the loss of lives,

LP presents the panic due to the loss of properties,

S presents the panic due to the Safety,

E presents the panic resulted in the Environment,

Q presents the panic in the Quality,

T presents the panic due to the Throughput,

O presents the panic due to loss of Operation,

I presents is the catastrophic panic of Immobilization,

The corresponding assumed weight “W” for which the probability Pw may follow equation (3).

Pw=1/1010-w (3)

where,

w is a weight factor denoting the severity of the event as related to the frequency and the consequences.

If the accident is categorized as predicted then measures for reducing the impacts and to prevent the occurrence of that accident must be implemented. That is as indicated by equation (4).

REST > RCAL (4)

where, REST is the estimated total frequencies of an event multiplied by the severity of consequences, and RCAL is the tabulated standard value at the corresponding associated Risk,


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calculated as shown in table II to be equal on average to 5. This value has been explained in the next part and Table II and summarized in Figure 5.

But if the accident is unpredicted to be non-expected, i.e., remote event, thus equation (5) shall be applied in this case.

REST < RCAL (5)

Fig. 5: Steps involved in the calculations of RCAL

6. DISCUSSION AND APPLICATIONS:

Table III summarizes some of the cases of the most recently experienced pipeline accidents. The utmost severe case as could be seen is that of Dalian. This accident has been in Dalian, Chinese port. The pipeline had experienced bursting explosion accident on 17th July 2010, as indicated in Table III. This accident must be treated as if it were expected. That means that the


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pipeline integrity should be thoroughly implemented should this type of accident be avoided within RCA implementation. Applying surveillance through good monitoring of the pipeline can for sure be reflected in the accident prevention.

It is to be noted here that applying the frequency per consequence and summing up the frequencies will yield the probability of the event. Depending on the estimated risk value the severity of the eventual accident either experienced or expected, or remotely and unexpected, implementing of RCA with advanced monitoring techniques will lead to better preventing the recurrence of the bad event. Thus the downtime and will be reduced enhancing better lifetimes of the concerned pipeline (s).

Table I: Typical consequence as well as the associated weight and the probability per event

Consequence Per event

Weight “W”*

Pw*

Severity Probability

of Occurrence

1- Loss of lives “LV” 9 10-1 High Frequent

2- Loss of property “LP” 8 10-2 High Frequent

3- Safety “S” 7 10-3 High Probable

4- Environmental “E” 6 10-4 Moderate Probable

5- Quality “Q” 5 10-5 Moderate Occasional

6- Throughput “T” 4 10-6 Low Occasional

7- Operating “O” 3 10-7 Low Remote

8- Reputation “R” 2 10-8 Low Remote

9- Immobilization “I” 1 10-9 Low Remote

(*) W goes up while P goes down

6.1 Derivation of Standard Estimated Risk

Table II [24] gives the guidance of risk assessment in accordance with ISO 17776 standards and regulations. The severity as denoted within the five matrix is A (rare), B (repetitive), C (operable), D (repetitive operative) and E (localized repetitive). The increase in probability of an event to occur is ascending commencing at A, while the highest is at E. The severity of the consequences can be seen by three grades of the resulted consequences, e.g., none serious, moderate and high damaging. Thus the assessed risk is being either intolerable for events C, D and E if the severity is 3, 4 and 5 respectively. The second followed category is for reduced


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measure incorporated risk, e.g., for all events from A to E but the Severity is between 2 up to 5. The third category of the assessed risk is that for all probabilities from A through to E is at a severity of consequences of poor, e.g., 0 and 1.

Table II shows the estimated risk value for the extreme severity at weight parameter of 0.1, the average probability is set at 50% and the experienced Consequences are those shown in column “C” of table II. Values of “C” for pipelines have been quoted from references [24]. The total Critical Estimated Risk as seen in this table is 5.

Thus if the actual calculated risk is below this value then the accident is said to be unexpected nevertheless it happened. But if the actual calculated value is above 5, then the event is to be expected and thus awareness and asset integrity management in pipeline field of practice must be thoroughly implemented to find a proper solution to the pipeline problem. Applications of the proposed risk assessment compared with those of the ISO 17776 are shown and summed up in Table III and Appendix I.

Table II: Estimated Average Standard Risk value, REST

Event

Causes and Reasons

C = Consequences, S = Severity,

Pavg = Average Probability

Estimated

Risk (*)

C S Pavg [Column 6]

C*S*Pavg

P (**)

A Poor Design, or wrong material, and /or misuse due to bad operation

36 0.1 0.50 1.800 0.36

B Wrong specification 16 0.1 0.50 0.800 0.16 C Poor planning 14 0.1 0.50 0.700 0.14 D Human error 12 0.1 0.50 0.600 0.12 E Bad inspection 10 0.1 0.50 0.500 0.10 F Damage to Health 8 0.1 0.50 0.400 0. 08 G Damage to Environment 4 0.1 0.50 0.200 0.04

∑= 100 * REST = ∑C x ∑S x ∑P ** P = [Column 6] /[∑Cx∑Sx∑P]

5.000

1.00


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Table III Applications of the proposed risk assessment as indicated in Figure 5 compared with the ISO 17776 in major cases of pipelines hazard accidents, RCAL = P * C, Rest== 5.000, estimated at Pw 0.1

Fig. No. Cause and Reason Sum of Consequences

CT CT/100 P

10β

N NT-9

CR CT*N/

9

C

CR x PW

RCAL

[P*C]

ISO 17776

P S Risk

Fig. I.1 Heavy corrosion A+B+C+D+E 88 0.88 1.318 5 48.89 4.889 6.45 E 5 IN

Fig. I.2 Leak due to corrosion A+B+C+D+E+F 96 0.96 1.096 6 64.00 6.400 7.02 E 6 IN

Fig. I.3 Bent erosion A+C+E+G 64 0.64 2.291 4 28.44 2.844 6.52 D 4 IN

Fig. I.4 Poor material A+C+G 54 0.54 2.884 3 18.00 1.800 5.19 C 3 IN

Fig. I.5 Stress Corrosion Cracking A+B+C+D+E+G 92 0.92 1.202 6 61.11 6.133 7.37 E 6 IN

Fig. I.6 Crevice Corrosion A+C+E 60 0.60 2.477 3 20.00 2.000 4.95 B 3 T

Fig. I.7 Leak due to wrong Design A+C+D+E+F+G 74 0.74 1.820 6 49.00 4.933 9.00 E 6 IN

Fig. I.8 Leak due to severe corrosion A+B+C+D+E+F+G 100 1.00 1.000 7 77.77 7.778 7.78 E 6 IN

Fig. I.9 Miss Operation condition A+C+D+F+G 74 0.74 1.820 5 41.11 4.111 7.84 C 5 IN IN = Intolerable T = Tolerable

7. CONCLUSIONS

From the investigated work shown within the text of this paper the following main conclusions could be drawn:

1) Corrosion is the primary epidemic by which pipelines can be deteriorated and resulted in degradation of integrity. Most pipelines corrode on contact with water (and moisture in the air), acids, bases, salts, oils, aggressive metal polishes, and other solid and liquid chemicals contained within the flow inside the pipeline. All will tend to increase the explosions, bursting and fires if the pipeline will contain flammable material, especially if the pipeline will carry materials like acid vapors, formaldehyde gas, ammonia gas, and sulfur containing gases as the cases in petrochemical and fertilizing factories. Thus the risk for each pipeline should be defined by RCA and the investigation of the consequences must be defined.

2) The simple observation has a major impact in many aspects of accident prevention and control, by applying new monitoring techniques to avoiding the most insidious or localized forms of bursting within a pipeline. The national income and the economic plans of growth in any country, nevertheless, whether it is developed or still underdeveloped one, may be found to depend and drastically affected by the utility and the efficiency of the pipeline projects. As the corrosion is known to be the main predominant source of annoyance to all,


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thus an International environmental contingency plan taking into consideration the impacts of corrosion rates within the global warming universal phenomenon must be enhanced.

3) Root cause analysis shall be applied to investigate previous cases of pipeline accidents, while for new recent cases the approach shall be based on risk which is composed of the frequency based calculations taken from root cause analysis multiplied by the consequences of the pipeline accident. The value of the calculated risk then has to be compared by those limits stated by Codes. If it were very high then an alternative solution must be applied to reduce as well as to control the results from the pipeline accident. This has been furnished as seen in the derivation of risk of pipeline integrity.

4) The devised formalized standard risk assessment can be used as a guidance to \\ devising

counter measures to reduce the resulted hazard. The derived examples show that most of those pipeline accidents can be categorized as expected. Therefore the counter action of not repeating the same accident again, i.e., RCA must be applied and thoroughly implemented.

5) The specific tool of QRA (Quantitative Risk Assessment) is subjected to criticism, partly because the technique is too academic, and partly because there is insufficient agreement within the industry and the HSE on how to use the results of QRA. So, the suggested guided standard risk assessment has taken all those handicaps into consideration. The assessment is based on quantitative weight factors that if properly determined then the Consequences in values can be assessed. Also, implementing standard risk values will lead to better decisions and will enhance the implemented guidelines. All will lead to reduction in the recurrence of the event and its impact.

6) The management of a pipeline project must be aware to ensure that the relevant statutory provisions will (in respect of matters within his control) be complied with in relation to the installation and any activity on or in connection with it; established adequate arrangements for audit and for the making of reports thereof; also, that all hazards with the potential to cause a major accident have been identified; and that the risks have been evaluated and measures have been, or will be, taken to reduce the risks to persons affected by those hazards to the lowest level that is reasonably practicable in accordance with HSE Act 1992 and 1998 Reg. 8.

7) Modern risk management approaches applied in pipelines integrity make clear that risk assessment has an important role to play in many risk-related decisions, particularly for decisions involving uncertainty, deviation from standard practice and risk trade-offs, for which pipeline regulations are less appropriate. The decision support framework provides a suitable basis for such decision-making. The HSE tolerability of risk framework shows how risk assessment can contribute to such decisions. As is noted from the nine applications the proposed model is based on thorough assessments for the consequences and the risk of the event. The assessments as shown are in matching and in good agreement with those obtained applying the ISO 17776 model.


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8. REFERENCES

[1] El-Gammal, M.M. (Sr.), El Naggar, H. H., El-GAMMAL M.M. Jr. (2010) “Life cycle integrity management approaches sighted for pipelines for desert use with practical designs and applications,” WORKSHOP “C”, 1st Asset Integrity Management Egypt, IQPC June

[2] EL-GAMMAL, M.M. (1995) “Fitness for Performance Reliability Approach towards Safety of Pressure Vessels,” AMPT'95, International Conference, Dublin City University, Ireland,

[3] EL-GAMMAL, M.M. Sr. El Naggar, H. H., El-GAMMAL M.M. Jr. (2009) “Mitigation approaches to minimize corrosion accidents in pipelines with practical industrial case studies, 4th Annual Middle East Pipeline Integrity Management Summit, Le Meridian, Abu-Dhabi Hotel & Resort, Abu Dhabi, UAE

[4] EL-GAMMAL, M.M. (1997) “Fitness for Performance Approach Applications to Welded Joints in Marine & Non-Marine Welded Structures,” 6th. International Conference on Theoretical and Applied Mechanics, Academy of Science and Technology, Cairo, Egypt, March

[5] EL-GAMMAL, M.M.:”Reasons and means of corrosion with proposed methods of protection in offshore structures,” IQPC- Workshop C- Pipeline Planning and Integrity Management Summit, UAE, Abu-Dhabi, 24 February – 27 February 2008

[6] EL-GAMMAL, M.M. (2002) “Optimization Technique for Recycling of Engineering Structures Based on Probabilistic Fracture Mechanics and Risk Analysis,” SIAM Optimization Conference, Toronto, Canada,

[7] EL-GAMMAL, M.M. (2003) "Fatigue Life Prediction in the Presence of Inherited Defects & Corrosion with Marine Applications," IMRASET Publications, Journal of Marine Design and Operations, Proceedings of Marine Engineering, Society and Technology, No. B3, PP. 3 – 8

[8] EL-GAMMAL, M.M. (1975) “A New Method for Estimating the Fatigue Life of Ship Structures, “International Shipbuilding Progress, vol. 22, November, pp. 349-363

[9] EL-GAMMAL, M.M. Co-author (1983) “Statistical Evaluation of Fatigue Life of Welded Joints. Theoretical Approach, “Qualtest-2, Conference, October, Dallas, Texas, USA

[10] EL-GAMMAL, M.M. (2007) “Principles and anatomy of reasons of corrosion in marine structures,” The 9 th Arab International Conference on Materials Science, Alexandria, Egypt,

[11] SMITH, R. (2005) “Asset_integrity, what_to_do_after_an_economic_crisis,” A culture of reliability, http://reliabilityweb.com/i2005,ndex.php/articles/asset_integrity_what_to_do_after_an_economic_crisis

[12] EL-GAMMAL, M.M. (2001) "Relationship between Arc Welding Processes and the Evolution of Corrosion in Welded Joints: Reasons and Remedies," 7th International Conference on Production Engineering, Design and Control, Alexandria, Egypt, Vol. III, February, pp. 1847-1862

[13] EL-GAMMAL, M.M. (1997) “Scheme of Coating and Surface Treatment for Improving Corrosion Resistance with Application to Marine Structures,” Vol. III – Advances in Surface Engineering, Engineering Applications The Royal Society of Chemistry, London, , ISBN-0-85404-757-3, Paper No. 3-6-2, pp.315- 324


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[14] EL-GAMMAL, M.M. and MENISSI, A. (2010) “Review and study of quality management tools in shipbuilding industry,” Engineering Systems Management Graduate Program, the Second International Conference on Engineering Systems Management & Applications,“ Solutions for Regional and Global Challenges, American University of Sharjah, UAE. March 30–April 1, and also IEEE, 09 August 2010, ISBN 978-1-4244-6520-0, http://ieeexplore.ieee.org/Xplore/login.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F5523174%2F5542651%2F05542673.pdf%3Farnumber%3D5542673&authDecision=-203

[15] EL-GAMMAL, M.M. Sr. El-NAGGAR, H.H., EL-GAMMAL , M.M. Jr. (2009) “improving processes for effective corrosion and cracking prevention by implementing advanced protection and repair solutions,” Workshop C, 5th Annual Asset Integrity Management Summit, 25th February 2009, LE Meridian, Abu Dhabi, UAE

[16] El-GAMMAL,M.M. (2009) “Remedial Maintenance Approach towards Recycling lifetime Applied to Mechanical Broken and Damaged Industrial Components, 8TH International Operations, Maintenance Conference, OMAINTEC, Beirut, Lebanon, 6-9- July

[17] El-GAMMAL, M.M., SULIMAN, A.M. (2009) “Deep-water marine riser systems lifetime and fracture integrity prediction and assurance, IMAM 09, Istanbul, Turkey, 12-15 October

[18] El-GAMMAL, M.M. (2010) “Discussing surface coating pipeline procedure against corrosion for mechanical and civil applications,” Workshop E, IQPC 24th February, Sheraton Abu Dhabi Hotel & Resort, UAE

[19] El-GAMMAL, M.M. (2010) “Application and Remedial Maintenance Approach towards recycling lifetime Applied to Mechanical Broken and Damaged Industrial Components.” Paper submitted to OMAINTEC & Hariri 2009 Awards: 8TH International Operations, Maintenance Conference, OMAINTEC, Beirut, Lebanon, 6-9- July

[20] El-GAMMAL, M.M. (2010) “Techno-economical remedial maintenance approach towards recycling lifetime with industrial applications,” Workshop 8, 9TH International Operations, Maintenance Conference, OMAINTEC, Beirut, Lebanon, 7-10 June

[21] EL-GAMMAL, M.M. (2010) “Enhancing the procedure and scheme of passive surface protection for pipelines against corrosion to extend life-cycle and reduce environmental hazards and pollution, “ PAPER, 5TH Annual Asset Integrity Management Summit, 21ST February, Sheraton Abu Dhabi Hotel & Resort, UAE

[22]ALBERT VAN ROODSELAAR CHEVRON, “RBI of offshore platforms,” http://www.api.org/meetings/proceedings/upload/rbi_of_offshore_platforms_albert_van_roodselaar.pdf

[23] DET NORSKE VERITAS (2002) “Marine risk assessment- HSE,” TECHNOLOGY REPORT 2001/063, LONDON CONSULTANCY PALACE HOUSE 3

[24] JONES, D. (1999) “Corrosion risk assessment for oil and gas production facilities methodological approach,” CESCOR, http://www.cescor.it/pdf/CRA.pdf

[25] NATIONAL SAFETY TRANSPORTATION BOARD (2008) “Explosion, release, and ignition of natural gas,” Rancho Cordova, California, December, http://www.ntsb.gov/publictn/2010/PAB1001.htm

[26]DALIAN PORT PIPELINE EXPLOSION AND FIRE ACCIDENT- 17TH JULY 2010 http://www.boston.com/bigpicture/2010/07/oil_spill_in_dalian_china.html

[27]DEEPWATER HORIZON (2010) http://www.offshore-mag.com/index/articledisplay/4402542152/articles/ offshore/deep water-horizon/update-on_deepwater2.html


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APPENDIX I: Pipeline Failure Examples

Major pipeline failures are mainly due to one or more of the following. Gas and oil pipelines have established an impressive safety record over the years. Some of the causes of failures are identified in this commentary, other causes are mainly due to one or more of being subjected to mechanical damage resulted from: fatigue cracks or material defects, or fabricated inherited defects, e.g., weld cracks, incomplete fusion, improper repair welds, incomplete penetration, or external or internal corrosion and or hydrogen blistering. Mechanical damage normally consists of gouges and dents. They generally are created by excavation or handling equipment during construction.

1- Sudden catastrophic failures due to mechanical damage resulted from corrosion degradation, Figures I.1, shows typical deteriorated pipelines in petrochemical industrial factories. The total estimated consequences is as follows: ∑ C = A+B+C+D+E = 88,

Figures I.1: Typical corroded pipelines in petrochemical Factories, expect as disaster [20]

2- Leak of flammable oil and gas lead to entire explosion of pipeline at Hertfordshire Depot north of London in 2004, Figures I.2. Results from this accident were loss of lives as well as loss of property and can cause fire hazards, ∑ C=A+B+C+D+E+F = 96,

Figures I.2: Pipelines carrying flammable materials are the main source of fires [25]


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2- Heavy erosion in elbows and bent connections, may lead to dangerous hazards, Figures I.3, the resulted consequences are estimated from: ∑ C = A+C+E+G = 64,

Figures I.3: Heavy corrosion due to erosion in pipeline bents [21]

3- Fatigue cracks in the presence of corrosive agression envieronment that have been redulted from bad fabrication were the main source for dismantling of offshore pipeline, Figures I.4. The estimated consequences for the offshore pipeline and the exhaust pipe are as follows: ∑ C = A+C+G = 54,

Figures I.4: Dismantling due to fatigue cracks of undersea pipeline and fatigue cracked exhaust pipe [21]

5- Stress Corrosion Cracking, is the main source of pipeline failures, Figures I.5, ∑ C = A+B+C+D+E+G= 92,

Figures I.5: Wrinkled Pipeline Failed in Compression due to Stress Corrosion Cracking [25]


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6- Crevice Corrosion Cracks, is another source of corrosion as shown in, Figures I.6, The estimated consequences is as follows: ∑ C= A+B+C+E = 50,

Figures I.6: Typical cases of crevice corrosion cracking in pipelines [21]

7- Pipeline Explosions An explosion failure investigation involves determining the root cause of the explosion. Oxygen and fuel (gasoline, liquefied propane, natural gas, etc.) must be present in the proper proportions for an explosion to occur. Also, there must be an event that ignites the oxygen/fuel mixture to create the explosion. RCA provides engineering support of your pipeline, b oiler, or petrochemical plant explosion, Figures I.7, [25], ∑ C = A+C+D+E+F+G=84

Figures I.7 Left photo for the pipeline Right is some of the habitat resulted damages due to the pipeline explosion, [25]

Dalian Port, China,

On17th July 2010, Pipeline accident: Dalian, China [26], two oil pipelines were exploded, sending flames hundreds of feet into the air and burning for over 15 hours, destroying several structures - the cause of the explosion is under investigation. The damaged pipes released thousands of gallons of oil, which flowed into the nearby harbour and the Yellow Sea. The total amount of oil spilled is still not clear, though China Central Television earlier reported an


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estimate of 1,500 tons (400,000 gallons), as compared to the estimated 94 – 184. Million gallons in the BP oil spill off the Louisiana coast. The oil slick has now grown to at least 430 square kilometers (165 sq. mi), forcing beaches and port facilities to close while government workers and local fishermen work to contain and clean up the spill, Figures I.8, ∑ C= A+B+C+D+E+F+G = 100,

Figures I.8.a: Left photo denotes the initial reason for the fire explosion accident and the hazard. Right photo defines panic consequences of the leak accident drowning of two fire

fighters in the oil slick lake

Figures I-8.b: Resulted Consequences of the fire explosion of Dalian Port, China, 17th July 2010

Figures I.8: Part of the damaged pipelines after the fire off Yellow Sea after covering with the slick oil spill [26]

9. DEEPWATER HORIZON [27]

This tragedian case shall be dealt with in a separate paper due to the importance of applying the RCA into this case. The dilemma starts on 17th February when all of a sudden the Deep-water Horizon has been collapsed and foundered unto the water of the ocean. During the accident the


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dynamical resulted forces were in excess to the extent that the riser pipeline has been torn off, causing at first white smoke of CO to come out first and then the black oil has been flown off causing a very large destruction to the echo0systems and badly affecting the environment till reaching the coast of Florida. The BP has done its best to stop the oil spill but after a period of almost 90 days of fighting they have succeeded to kill the reservoir and to stop the oil from coming out applying the mud-cement mixture vacuum concept. If they have applied this concept from the beginning then there will be no bad resulted consequences either on neither the environment nor the exaggerated period of time taken during the trial and error solutions. Thus it was a case of wasting money, effort and great nuisance to all involved in this matter Figures I.9. ∑ C A+C+D+F+G =74,

Figures I.9: Case of Deep-water Horizon- The right photo shows the mechanism of the disaster. The white cloud fog came first then followed by the black oil [27].


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DURABILITY OF CONCRETE STRUCTURES IN THE ARABIAN GULF: STATE OF THE ART AND IMPROVED

SCHEME

Reem Sabouni∗ Civil Engineering Department, ALHOSN University, P. O. Box: 38722, Abu Dhabi, UAE

ABSTRACT: The Arabian Gulf region has witnessed an extensive urbanization development during the last three decades. Due to its many favorable characteristics concrete, has been the most widely used construction materials associated with this development. Despite the many advantages of reinforced concrete as a construction material, the service life its structures was found to be significantly below averages standards in the Arabian Gulf region compared to other parts of the world. Signs of concrete degradation and distress have been witnessed as early as 5 years in its life time. This is mainly due to the harsh environment of the Arabian Gulf region and even more aggravated with the malpractice in the concrete construction which is witnessed in many projects in the region. The common concrete deterioration mechanisms observed in the Arabian Gulf region are discussed in this paper, followed by some prevailing durability related practices in the region. This paper concludes with proposing a scheme “Concrete Durability Up Front” that guides the engineer though several steps to reach to one of three expected levels of concrete durability depending on the type of durability measures implemented in the project. KEYWORDS: Concrete durability, additives, admixtures, Arabian Gulf, carbonation, chloride penetration, reinforcement, steel corrosion, sulfate attack. 1. INTRODUCTION

In the Arabian Gulf region it concrete deterioration was witnessed very early in the structure’s life cycle. This is attributed to the harsh environment of the region where statistical data showed that temperatures may reach to above 45 oC in some parts and the humidity at coastal areas may reach up to 100% [1]. What aggravate the durability conditions in the Arabian Gulf region are the malpractices associated with the quick fix approaches resulting from the fast track construction trends in the region. This resulted in an increase tendency of using trial and error approaches among practicing engineers to fix the durability problem. This lead to a rush in commercially motivated techniques and applications that are not fully tested or standardized, and claim that they give the cure for durability problems of reinforced concrete structures [2]. What aggravated the harm is that these techniques were applied with inadequate supervision and considered as alternatives to adhering to the strict standards of good practice and workmanship of concreting. Often, durability-enhancing materials and techniques are applied in the building construction in the Arabian Gulf with inadequate supervision, lack of quality assurance, and poor quality control leading to low efficiency in results [3]. This calls for the need of studied schemes to link the durability practices with

∗ Corresponding Author. Tel.: +971 4070715

E-mail: [email protected]

___________________________________________* Corresponding Author.Tel.: +971 4070715, E-mail : [email protected]


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proper quality control measures. On the other hand, there is a promising rise in the concrete durability awareness in the Arabian Gulf region [4, 5].

This paper will begin with discussing the main concrete degradation mechanisms in the

Arabian Gulf region such as sulfate attack, carbonation, chloride corrosion, and cracking due to environmental effects. This discussion will be followed by surveying the prevailing durability related practices in the region. The paper will be concluded by proposing a scheme to improve the durability in the Arabian Gulf region.

2. MAIN CONCRETE DEGRADATION MECHANISMS IN THE ARABIAN GULF REGION

The American Concrete Institute defines the concrete durability as the weathering action, chemical attack, abrasion and other degradation processes [6]. Concrete is a synthetic rock that will end its life cycle as silica sand, clay and limestone. The more durable the concrete the longer this process will be delayed [7]. Only the main concrete degradation mechanisms attributed to lack of adequate durability will be considered in this paper. They can be categorized into four classes: Sulfate attack, carbonation, chloride corrosion, and cracking due to environmental effects. A brief description of each type is given in the following.

2.1 Sulfate Attack

Sulfate attack is a common form of concrete deterioration that occurs when concrete comes in contact with alkali soils or water such as soils when arid conditions exist, in seawater, and in wastewater treatment plants. The most common types of sulfates are sodium, calcium and magnesium sulfates (which are less common, but more destructive). Potentially all sulfates are harmful due to their chemical reaction, with the hydrated lime, hydrated calcium aluminates and the cement paste, that produces solid products with larger volumes than the input product [8]. Figure 1 shows an illustrative diagram on the process of sulfate attack.

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Figure 1: An illustrative diagram on the process of sulfate attack [8].

Principal factors that affect the rate and severity of sulfate attack are:

1. C3A content. 2. Permeability of the concrete. 3. Ca(OH)2 content. 4. Concentration of sulfates in the waterborne solution.

In the coastal areas of the Arabian Gulf, the capillary rise of moisture and frequent flooding followed by intense evaporation leaves a heavy crust of salt in the topsoil. When concrete structures are exposed to sulfate solutions, or are placed in sulfate-bearing soils or ground waters they are subject to sulfate attack deterioration. One of the most common ways of protecting against sulfate attack is to reduce the alumina content by limiting the C3A in Portland cement. Historically, Type II Portland cement (with C3A between 5% and 8%) and Type V Portland cement (with C3A less than 5%) have been specified for moderate and severe sulfate environments, respectively. To minimize damage to concrete due to sulfate attack it is a common practice in the Arabian Gulf to use Type V cement in the structures in contact with or below the ground. Sulfate resistance of the concrete is improved by a reduction in water-cement ratio and an adequate cement factor, with a low tricalcium aluminate and with proper air entrainment. With proper proportioning, and strict quality control, silica fume (microsilica), fly ash and ground slag generally improve the resistance of concrete to sulfate attack, primarily by reducing the amount of reactive elements (such as calcium) needed for expansive sulfate reactions [3].

Studies conducted by Al-Amoudi and Maslehuddin [9] pertinent to sulfate attack in the presence of chloride indicated some beneficial role of chloride ions on sulfate attack. The

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mechanisms are explained based on the contention that in the presence of chloride less trisulfate (ettringite) is formed. This reduction in trisulfate is attributed to the fact that its solubility is increased by chloride ions and that a part of the triculcium aluminate which creates ettringite formation is combined as calcium chloro-aluminate. Further, it is believed that trisulfate crystallizes from the solution when chloride is present, because of the higher solubility of trisulfate in chloride-containing solutions and so it does not cause expansion. Another important finding of this study was the accelerated deterioration of silica fume and blast furnace slag in the magnesium sulfate environment, and the chloride beneficiation was not observed in these cements [10].

2.2 Carbonation

The reaction between the products of cement hydration and the acidic gases in the atmosphere is namely the carbonation of concrete. The main acidic gas normally available in the air in relatively low concentrations (0.03%) is (CO2). This concentration is usually higher in industrial atmospheres were the problem of concrete carbonation arises. Carbonation reduces the alkalinity of the concrete to a pH value of about 10 and, accordingly, concrete protection of the reinforcing steel is lost, which leads to the corrosion of the reinforcing steel. The expansion of the metal reinforcing embedded in the concrete due to this corrosion causes severe damage to the reinforced concrete structure such as spalling and delaminat ion. Figure 2 shows an illustrative diagram on the process of carbonation of reinforced concrete. A good quality concrete sufficiently reduces the damage due carbonation because this process becomes very slow. As well carbonation will not occur when concrete is constantly under water [8].

Figure 2: An Illustrative diagram on the process of carbonation of reinforced concrete [8].

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The hot and humid weather of the Arabian Gulf is conducive for carbonation of cement, that is why it is not uncommon to see sometimes carbonation of concrete to the rebar level. In-situ investigations conducted by Hussain, et. al., 1994 [11] on a reinforced concrete structure in an industrial area along the Arabian Gulf, indicated carbonation to a depth of 15 mm on the exterior components, whereas on the interior components it was 3 to 5 mm, after about six years. Carbonation of cements is accelerated by chloride and sulfate contamination. Other studies [12] reported a greater depth of carbonation in the contaminated cement mortar specimens than in the corresponding uncontaminated specimens. The increased carbonation in the contaminated cements is attributed to the changes in the pore structure of cement due to the inclusion of contaminants. This trend of increased carbonation in the contaminated specimens was also observed in the blended cements. This is of concern, because blended cements usually include imported costly materials.

2.3 Chloride Corrosion The chloride-induced reinforcement corrosion is a major form of concrete deterioration in the Arabian Gulf [13]. The concrete itself is not directly affected by the chloride ions but they cause severe damage to the reinforced concrete structures by the corrosion and expansion of the metal reinforcing embedded in the concrete. There are two main sources of chloride ions in the concrete: penetrated chlorides from the service environment and cast-in chlorides contributed by the mix constituents. Figure 3 shows an illustrative diagram of the chloride penetration and the associated reinforcing steel corrosion process for cracked and uncracked reinforced concrete sections. Chlorides occur in either acid soluble or water soluble form. The most damaging is the water soluble chlorides since they readily become free to attack surrounding reinforcing steel. If care is not taken in picking the used concrete mix constituents chlorides can be found in reinforced concrete even before the structure is in service. For instance if beach sand is used as fine aggregates, having seawater for mixing or in the form of natural ingredients found in some aggregates [8]. Table 1, shows the ACI 201.2 R [6] suggested limits for chloride ion in concrete prior to placing concrete into service.

Table 1: Limits for chloride ion in concrete prior to placing based on ACI 201.2R [6].

Service Condition Chloride to weigh of cement % Prestressed concrete 0.06 Conventionally reinforced concrete in a moist environment and exposed to chloride

0.10

Conventionally reinforced concrete in a moist environment not exposed to chloride

0.15

Above-ground building construction where concrete will stay dry

no limit


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Figure 3: An illustrative diagram of the chloride penetration and the associated reinforcing steel corrosion process: a) Cracked reinforced concrete, b) Uncracked reinforced concrete [8].

In substructures, reinforcement corrosion is mostly attributed to the chlorides diffusing from the soil and/or ground water. In the superstructure, reinforcement corrosion in majority of the cases is attributed to chloride ions contributed by the mix constituents. Another important factor which has accelerated concrete deterioration due to chloride-induced reinforcement corrosion is the conjoint presence of chloride and sulfate ions in the soil and ground water, or the mix constituents. The presence of chloride in association with sulfate concentration, increases the corrosion rate, this is of concern for underground structures, where both chloride and sulfate salts are normally present. For superstructures the effect of high temperature aggravates the problem of chloride-induced corrosion [10].

It is imperative that chloride and sulfate contamination contributed by the mix constituents is minimized. It is a common practice to wash the aggregates to achieve this goal. Other factors affecting chloride-induced reinforcement corrosion are the quality of concrete, and the concrete cover. Poor quality of the hardened concrete, due to inadequate consolidation, curing, insufficient and non-uniform cover often lead to reinforcement corrosion, even though chloride contamination is within acceptable limits. The strength, depth of cover and diffusivity of the concrete all play a role in the prevention of chloride-initiated corrosion of reinforcement. Cracks and construction joints in concrete aggravate the chloride penetration. They allow corrosive chemicals such as deicing salts to enter the concrete and access embedded reinforcing steel [14].

In the Arabian Gulf environment, Al-Amoudi and Maslehuddin [9] investigated reinforcement corrosion in the cement paste specimens exposed to chloride, sulfate and chloride plus sulfate environments. The results of this study indicated that while the sulfate ions were hardly able to

a b

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induce reinforcement corrosion, considerable corrosion activity was observed in the specimens immersed in the sodium chloride plus sodium sulfate solution. Reinforcement corrosion was observed to increase by almost two times when the sulfate concentration in the 15.7% chloride solution was increased from 0.55 to 2.10%.

2.4 Environmental Cracks

There are several causes of cracking; but the cracking of concrete structures at early ages is the cause most related to durability. To support the high speed of modern construction trends, high-early strength concrete mixtures are used. Early age cracking is usually associated with the use of these types of concrete mixes. These cracks may form, by allowing moisture and oxygen to the steel surface, focal points for the other forms of deterioration. Although these cracks may develop at normal temperature but with hot weather conditions such as that in the Arabian Gulf it is of a major concern.

There are no clear guidelines in the ACI Manual of Construction Practice on the relationship between crack width and durability of reinforced concrete structures exposed to different environmental conditions. Although ACI 224R-01 [15] report suggests 0.15 and 0.18 mm as maximum tolerable crack widths at the tensile face of reinforced concrete structures exposed to deicing chemicals or seawater, respectively (see Table 2), the report also contains a disclaimer that the crack-width values are not a reliable indicator of the expected reinforcement corrosion and concrete deterioration [16].

Table 2: Tolerable crack widths in reinforced concrete based on ACI 224R-01 [15].

Exposure Condition Tolerable Crack Width (mm) Dry air, protective membrane 0.41 Humidity, moist air, soil 0.30 De-icing chemicals 0.18 Seawater and seawater spray; wetting and drying

0.15

Water-retaining structures 0.10

For a designer to exercise engineering judgment on the extent of needed crack control, at least some understanding of the effect of cracks and microcracks (less than 0.1 mm) on the permeability of concrete is necessary. A brief summary is presented herein. Generally, at the interfacial transition zone between the cement mortar and coarse aggregate or reinforcing steel, a higher than average (w/cm) exists, which results in higher porosity, lower strength, and more vulnerability to cracking under stress. Thus, when a structure or a part of the structure is subject to extreme weathering and loading cycles, an extensive network of internal microcracks may develop. Under these conditions, the presence of even a few apparently disconnected surface cracks of narrow dimensions can pave the way for penetration of harmful ions and gases into the interior of concrete [16].


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To the best of the author’s knowledge, there are no readily available standards that fit the local environmental and practice conditions in the Arabian Gulf. ACI Committee 305 guidelines for concreting under hot weather conditions [17] may not be readily applicable to the Arabian Gulf region environment. The ACI 305 chart for calculating the rate of evaporation (Figure 4) is based on a formula that firstly, does not account for the possibility of shrinkage cracks and secondly, this chart is not valid for ambient temperatures of more than 38 °C. Further, the evaporation rate formulas can be applied only when the surface is completely covered with water [10].

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Figure 4: Effect of concrete and air temperatures, relative humidity, and wind speed on the rate of evaporation of surface moisture from concrete (Courtesy of Portland Concrete Association Journal 1957) [17].

3. COMMONE CONCRETE DEGRADATION PREVENTIVE TECHNIQUES IN THE ARABIAN GULF REGION

Preventing concrete degradation should be a main consideration when designing any concrete mix or picking materials for reinforced concrete structures especially in the Arabian Gulf due to its harsh environment. In the mid 80’s Somerville (1986) [18] has proposed the “4Cs of Concrete Durability” which are:

1. Constituents of the concrete mix; 2. Cover to the reinforcing steel; 3. Compaction; and 4. Curing.

Several durability enhancing mechanisms have been proposed and tested since then. In general the durability of concrete can be enhanced by: proper concrete mix design, providing better protection of the concrete and the steel reinforcement. These will be discussed in a conduct relevant to the Arabian Gulf.

3.1 Preventive Techniques Related to the Concrete Mix Design The durability performance of concrete is mainly influenced by the following mix design parameters: water cementitious materials ratio, cement content and grading and size of aggregates. Incorporating supplementary cementing materials may be further decreased the concrete permeability. Some of the most common supplementary cementing materials are: fly ash, blast furnace, slag and silicafume [19]. However, in the Arabian Gulf; the use of supplementary cementing materials should be considered with caution, due to two reasons. Firstly, the success of the use of the durability enhancing admixtures and additives requires strict control on mixing and curing condition, often not guaranteed in the climatic conditions and the prevailing construction practice of the Arabian Gulf, and secondly, these materials are often used purely for economic reasons rather than their technical merit. As in other parts of the world, fly ash, blast furnace slag, and silica fume cement have been used in the Arabian Gulf to improve the denseness of concrete. While blast furnace slag cement has been used in a few structures, fly ash and silica fume, particularly the latter is now widely used in new structures and for repair of the old structures. 3.2 Preventive Techniques Related to Enhancing the Concrete Protection

To improve the service life of reinforced concrete structures its surface can be treated with materials such as: penetrants, sealers or coatings. The main function of these treatments is to prevent aggressive species such as moisture and chlorides from reaching to the steel reinforcement. Swamy and Tanikawa [20] studied four different coatings used in the Arabian Gulf area for their ability to control chloride penetration and protect the steel from corrosion.


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This study was carried out by conducting wet-dry or continuous salt spray tests. Based on the test results a highly elastic acrylic rubber coating was further tested for long term stability. For concrete free from chlorides and concrete with up to 1% (of the mortar matrix) sodium chloride contamination, it was found that the selected rubber coating was able to ensure long term durability and protect embedded steel by prevent the penetration of air, water and chloride ions. 3.3 Preventive Techniques Related to the Protection of Reinforcing Steel

3.3.1 Assuring the Quality of Reinforcement Cover: One simple but very important way of maintaining the protection of the reinforcing steel is taking good care of the quality of the reinforcing cover. Meaning, having a cover free of pockmarks and surface blemishes. A good quality cover is achieved by concentrated effort during placing the concrete in the cover area, good compaction (without trapped air bubbles or bleed water), high-quality formwork (such as controlled permeability form work) and excellent curing of the cover zone. Because of harsh climate conditions in the Arabian Gulf curing is of greater importance [21]. 3.3.2 The Use of Inhibitors: Inhibitors are chemical compounds added to the concrete mix to prevent embedded steel corrosion and should not have adverse effect on the fresh or hardened properties of the concrete [22]. The main inhibitors commonly used in the Arabian Gulf are discussed in the following paragraphs.

3.3.3 Chemical Corrosion Inhibitors Calcium nitrite is the most commonly used chemical corrosion inhibitors. Nitrites are an inhibitor that enhances corrosion durability by chemically reacting with the ferrous ions to produce a passive ferric oxide protective film that blocks active corrosion centers. The effectiveness of inhibitors in reducing reinforcement corrosion, in the presence of contaminants, such as chloride and sulfate, was evaluated by measuring corrosion potentials and corrosion current density. Most studies are based on accelerated test rather than long term [10]. The effectiveness of selected inhibitors in inhibiting reinforcement corrosion in concrete contaminated with chloride and sulfate salts was studied, and the effectiveness of inhibitors in reducing reinforcement corrosion, in the presence of contaminants, such as chloride and sulfate, was evaluated by measuring corrosion potentials and corrosion current density. The data developed in this study indicate that both calcium nitrite and calcium nitrate were effective in delaying the initiation of reinforcement corrosion in the concrete specimens made with sea water, brackish water or unwashed aggregate [10]. Mineral Corrosion Inhibitors The most commonly used mineral corrosion inhibitors in the Arabian Gulf are: Fly ash, Silica Fume, and Ground Granulated Blast Furnace. A brief description of each material with its advantages, and disadvantages in the Arabian Gulf is provided in Table 3.

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3.3.4 Reducing the Vulnerability of the Reinforcing Metals: Besides improving the properties of the concrete to enhance the durability of the reinforced concrete structure, reducing the vulnerability of the reinforcing metals will have a favorable effect on the durability. To achieve that stainless steel can be used as an alternative to ordinary reinforcing steel [23]. On the other hand, the ordinary steel can be either galvanized or epoxy coated to improve its durability characteristics [21]. Fusion bonded epoxy coated (FBEC) bars are used in the Arabian Gulf in concrete structures exposed to chloride rich environments. They are usually specified for foundations and for reinforced concrete building components about one to two meters above the grade. There are two main concerns regarding these types of bars: the first is negative effect of surface damage and holidays on the steel corrosion and the second is the bond strength. Defect free bars should be specified if chloride ions are present in addition to meeting [24] ASTM A 775 [25].

Table 3: Mineral corrosion inhibitors commonly used in the Arabian Gulf. Material Advantages Disadvantages Cautions

Silica Fume or Microsilica

Fresh concrete: • Improves cohesiveness • less prone to segregation • reduces bleeding

Hardened concrete: • high strength concrete • low permeability, increases resistance to

chemical attack

Fresh concrete: • plastic shrinkage cracks,

care should be exercised to prevent early moister loss

• Ensure that silica fume used is specified to comply with one of the internationally standards

• Trial works must be done to ensure the compatibility of the silica fume with all the concrete components, and the proportioning

• Proper curing procedures must be followed to obtain the full benefits of the silica fume concrete

• due to some of the problems with placement of silica fume, additional care must be done when specifying SFC and the conditions under which it will be placed

Ground Granulated Blast-furnace Slag (GGBF Slag)

Fresh concrete: • more workability and placeability • increases time of setting, which is

desirable at higher temp

Hardened concrete: • improves long term corrosion resistance

of concrete by reducing permeability • improves sulfate resistance • reduces potential expansion of

concrete due to alkali-silica reaction

Fresh concrete: • plastic shrinkage cracks at

high temperatures • for courser GGBFS

bleeding increases

Hardened concrete: • greater creep and shrinkage

due to greater volume of paste in concrete when cement is substituted by GGBFS on equal mass basis

• concrete with GGBFS is more susceptible to poor curing conditions

• concrete with GGBFS must be kept in proper moisture and temperature conditions during its early stages to develop its strength and durability potential

Fly Ash

Fresh concrete: • improves plasticity cohesiveness • Reduces bleeding • improves pumpability • improves sulfate resistance • increases time of setting, which is

desirable at higher temperatures

Hardened concrete: • low permeability, increases resistance to

chemical attack • improves bond of concrete to steel • improves sulfate resistance • increases concrete resistance to chloride • reduces expansion reaction reactive

silica aggregates by consuming alkalis of Portland cement paste

Fresh concrete: • longer times of setting may

increase chances of plastic shrinkage cracking

Hardened concrete: • in case addition of fly ash

increases the paste volume the paste volume drying shrinkage may increased slightly if water content remains constant

• only fly ash with the right chemical composition and glass content will react sufficiently to achieve the strength and the ongoing pozzolanic reaction to lower long term permeability

• only few tested fly ashes would comply to international standards


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4. A PROPOSED SCHEME TO IMPROVE DURABILITY IN THE ARABIAN GULF

4.1 The need for a special scheme to improve the concrete durability in the Arabian Gulf:

The previous parts of the paper concentrated on the factors affecting the concrete durability that are associated with the Arabian Gulf region’s harsh weather. In fact, beside the harsh weather the construction practices pursued in the region have a major influence on the durability of the concrete structures [2]. The concrete industry has a unique situation in the Arabian Gulf (that is believed to differ for the rest of the world) due to a combination of factors. The Fast Track Construction Trends: The Arabian Gulf region has witnessed a rapid increase in the construction demand in the last decades. This called for the fast track construction trends that are followed nowadays and the increase in the required concrete strength. With the harsh weather in the Arabian Gulf these conditions are not usually favorable to durability requirements. To overcome the problem often this is falsely remedied by leaning towards the use of durability enhancing materials and admixtures [2].

4.2 The Rising Sustainability Construction Trends:

Several states of the Arabian Gulf region are employing more sustainable construction trends such as the Estidama [26] and the Plan Abu Dhabi 2030 [27] that are enforced in the capital of the UAE (Abu Dhabi). A number of other states in the region are following the same trends. Both the Estidama and Plan Abu Dhabi 2030 put great emphasis on environmental factors. Recently, the Estidama provisions have been applied as mandatory to the design permit approval of any building project in Abu Dhabi including private villas. The Esidama rates buildings according to its environmental factors into 4 categories with 1,2,3, or 4 Pearls. One of the main goals of Plan Abu Dhabi 2030 is to largely reducing the carbon footprint in Abu Dhabi City.

4.3 Absence of Local Code Provisions: In spite of the ongoing attempts to develop a regional or national code for the region, there is no national code of practice. A variety of international codes are used for the design and construction of reinforced concrete structures. The choice of the code is base on the company’s preference. Some of the widely used international codes are the US and British codes. Other codes are used –to a lesser extent- by some companies such as the: Canadian, European, and regional and local Arabic Codes.

4.4 Lack of Industrial Related Research: The durability of concrete in the Arabian Gulf resign is the focus of a good volume of research topics (some of which are referred to in different parts of this paper). The common shortage of these research topics is the absence of a strong link and coordination with the construction industry. Where, most of these researches are conducted for academic purposes. It would be beneficial for the construction industry in the Arabian Gulf to follow the common practice in North America and Europe of relying on industrial guided research to help in solving specific arising industrial problems.

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4.5 No or Little Accountability and Construction Liability: one of the major facts that influence the liability of the construction industry in the Arabian Gulf region is that the construction work is either performed by local companies that depend greatly on expatriates, or foreign companies that are allowed to get projects in the region due to the open market strategy. This tends to make engineers feel less liable if not committed to high engineering practice standards. Another liability issue is the vagueness in the insurance coverage of the different stages of the construction project.

4.6 The proposed scheme for concrete durability “Concrete Durability Up Front”:

Enhancing concrete durability should Start at an early stage in the project and be part of the structural design and specification of the project. However, this may be challenging for many construction projects in the Arabian Gulf. Designers are rarely well informed about the properties of various concrete mixes, and are unable to tell exactly what kind of concrete to use. In addition, sources of materials that the contractors may wish to use rarely adhere to standard quality control measures. Furthermore structural prescriptive specification for mixes is rarely used.

Herein, a scheme to improve the durability of concrete in the Arabian Gulf region is proposed (shown in Figure 5) and its rationale is explained. The scheme’s theme is “Concrete Durability Up Front”, where it guides the engineer though several steps to reach to one of three expected levels of concrete durability. If no durability measures are required by specifications (and none are carried out) the scheme expects a concrete deteriorate leading to a high maintenance cost for the structure under consideration. On the other hand, if specifications are required and the minimum specification requirements are met the scheme expects either that the concrete meets minimum durability standards or that the concrete is highly durable depending on the extra durability measures taken. If extra optional measures are shown to be feasible and will be implemented, a third party should assure the quality control process. This will mostly lead to highly durable concrete. The importance of the presence of the third party for quality control is due to the fact that even if the right durability measures are specified such as adding an admixture there is no guaranty that this admixture is applied properly with the absence of this third party. This is of great importance especially in the Arabian Gulf region where projects may not include reliable quality control for onsite concrete mixes or visits to mixing plants for ready mix concrete.


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Figure 5: The proposed scheme to improve durability in the Arabian Gulf “Concrete Durability Up Front”.

Concrete Durability Up Front

No

Meet the minimum requirements of specs

Yes

Further optional measures are

considered

Cost benefit analysis

Third Party Quality Control

Required by specifications

Feasible

Provided

Concrete expected to be highly durable

Concrete meets minimum durability requirements

Concrete expected to deteriorate resulting in high maintenance cost

No

No

No

Yes

Yes

Yes

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5. CONCLUSIONS

The durability of reinforced concrete structures is of great importance due to the wide use of this material in the construction projects in the Arabian Gulf region. To reach an acceptable level of durability this issue should be thought of in the early design stage of the project. This paper addresses the main four concrete degradation mechanisms in the Arabian Gulf region, then surveys the prevailing durability related practices in the region. Finally it concludes with the proposed scheme to improve concrete durability that has the theme “Concrete Durability Up Front”. The proposed scheme guides the engineer though several steps to reach to one of three expected levels of durability depending on the type of durability measures taken. If no durability measures are required by specifications and no special measures for durability improvement are taken the expected level of durability is low and concrete degradation is more likely to occur resulting in high maintenance cost. If the specifications require durability measures and those measures are taken, then a concrete meeting the minimum durability requirements is expected. Only with extra durability measures implemented, tied to proper quality control and third party involvement, a concrete with high durability and reduced maintenance cost can be achieved.

6. REFERENCES

[1] El-Hacha, R., Green, M. F., Wight, G. R., (2010) “Effect of Severe Environmental Exposures on CFRP Wrapped Concrete Columns”, Journal of composites for construction, ASCE, Volume 14, No. 1, pp 83-93.

[2] Sabouni, A. R., (2003), “Evaluation of Durability Enhancing Techniques for Structural Concrete in the UAE”, Proceeding of the 9th Arab Structural Engineering Conf. (Emerging Technologies in Structural Engineering), Nov. 29-Dec. 1, Abu Dhabi, UAE, pp 1217-1228.

[3] Sabouni, A. R. Editor, (1999), “Durability Enhancing Materials in Concrete”, American Concrete Institute UAE Chapter, ACI-UAE SP 99-1, USA, October 1999, pp 42.

[4] Alizadeh, R., Ghods, P., Chini, M., Hoseini, M. and Shekarchi, M., (2006), “Durability Based Design of RC Structures in Persian Gulf Region using DuraPGulf Model”, Concrete Repair, Rehabilitation and Retrofitting – Alexander (eds.), Taylor & Francis Group, London.

[5] Shekarchi, M., Ghods, P., Alizadeh, R., Chini, M., Hoseini, M., (2008), “DuraPGulf, a Local Service Life Model for the Durability of Concrete Structures in the South of Iran”, The Arabian Journal for Science and Engineering, Volume 33, Number 1B, pp. 77-88.

[6] ACI 201.2R (2001), “Guide to Durable Concrete”, American Concrete Institute, Farmington Hills, Michigan, USA.


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[7] Alshamsi, A. M., Sabouni, A. R., Alhosani, K. I., and Bushlaibi, A. H. Editors, (1994), “Reinforced Concrete Materials in Hot Climates”, Proceedings of the First International Conference on Reinforced Concrete Materials in Hot Climates, UAE University and the American Concrete Institute (ACI), Al-Ain, UAE, April 1994, 773 pp.

[8] Emmons, P. H., (1993), “Concrete Repair and Maintenance Illustrated, Problem Analysis, Repair Strategy, Techniques”, R. S. Means Company, 294 p.

[9] Al-Amoudi O. S. B., and Maslehuddin, M., (1993), “The Effect of Chloride and Sulfate Ions on Reinforcement Corrosion", Cement and Concrete Research, pp 139-146.

[10] Maslehuddin, M., (1997), Concrete Durability – The Arabian Gulf Experience, Symposium on Civil Engineering and the Environment, 3rd-5th May 1997, King Fahd University, Saudia Arabia, pp 1-12.

[11] Hussain, S. E., Paul, I. S. and Ruthaiyea, H. M., (1994), “Evaluation and Repair Strategies for Shallow Foundations”, Proc., 6th Middle East Corrosion Conference, Bahrain, pp 613-628.

[12] Maslehuddin, M.; Shirokoff, J., and Siddiqui, M. A. B., (1996), “Changes in the Phase Composition in OPC and Blended Cement Mortars Due to Carbonation”, Advances in Cement Research, October 1996, pp 167-174.

[13] Sabouni, A. R., (1998), “Corrosion, the Prime Cause of Deterioration of Reinforced Concrete Structures in the UAE” The Engineer Journal, No. 16, UAE University, Al-Ain, UAE, April 1998, pp 2-5.

[14] Malhotra, V. M. Editor, (2000), Durability of Concrete, Proceedings of Fifth International Conference, Barcelona, Spain, CANMET/ACI. 644 pp.

[15] ACI 224R (2001), “Control of Cracking in Concrete Structures (ACI 224R-01)”, American Concrete Institute, Farmington Hills, Michigan, USA.

[16] Mehta P. K., and Burrows R., (2001), “Building Durable Structures in the 21st Century”, Concrete International, American Concrete Institute, vol. 23, No.3, March 2001, pp 57-63.

[17] ACI 305R (2001), “Hot Weather Concreting (ACI 305R-01)”, American Concrete Institute, Farmington Hills, Michigan, USA.

[18] Somerville, G., (1986), “The Design Life of Concrete Structures”, The Structural Engineer, vol. 64A, No2, February 1986, pp 60-71.

[19] Gjorv, O. E., (2009), “Durability Design of Concrete Structures in Severe Environments”, Taylor & Francis Group, London, England.

[20] Swamy, R. N., and Tanikawa, S., (1993), “An External Surface Coating to Protect Concrete and Steel From aggressive Environments”, Materials and Structures, Volume 26, pp 465-478

[21] Neville, A., (2000), “Good Reinforced Concrete in the Arabian Gulf”, Materials and structures, Volume 33, pp 655-664.

[22] Lafave J, et al., (2002), “Using Mineral and Chemical Durability Enhancing Admixtures in Structural Concrete”, Concrete International, August 2002, pp 71-78.

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[23] Yunovich, M., and Thomson, N. G., (2003), “Corrosion of Highway Bridges: Economic Impact and Control Methodologies”, Concrete International, American Concrete Institute, vol. 25, No. 1, January 2003, pp 52-57.

[24] Eid, O. A., and Marwan, A. D., (2006), “Concrete in Coastal Areas of Hot-Arid Climate Zones, Extreme Conditions Accelerated Damage to Reinforced Concrete Structures”, Concrete International, September 2006, pp 33-38.

[25] ASTM A775, (2007), “Standard Specification for Epoxy-Coated Steel Reinforcing Bars”, American Society for Testing and Materials, West Conshohocken, Pennsylvania, USA.

[26] Abu Dhabi Urban Planning Council, (2008), “ESTIDAMA, Sustainable Buildings and Communities and Buildings Program for the Emirate of Abu Dhabi”, Abu Dhabi, UAE, 133 pp.

[27] Abu Dhabi Urban Planning Council, (2010), “Plan Abu Dhabi 2030”, Abu Dhabi, UAE, 185 pp.


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CAD AND 3D VISUALIZATION SOFTWARE IN DESIGN EDUCATION:

IS ONE PACKAGE ENOUGH?

Seif Khiati* Faculty of Engineering and Applied Sciences, ALHOSN University, Po. Box 38772 Abu Dhabi UAE

ABSTRACT: The present study will discuss the experience of using CAD and 3D software in design programs. Can one or two software packages be sufficient to allow students to visualize and express their ideas or is a larger selection of these packages indispensable? This paper reflects a series of discussions among the faculty and students in the departments of architecture at UAE and ALHOSN University. Although the first program in architecture in the UAE has existed since 1981, the discussion here focuses only on the last three years of using CAD and 3D software in the classroom. KEY WORDS: CAD, 3D visualization, education, computer, design. 1. INTRODUCTION Since the introduction of personal computers on campuses in the early Eighties, their role in educational programs has become central [1]. Today’s computers are both affordable and more powerful than their modest predecessors. Software has also matured and made things easier including in CAD and 3D programs [2]. As computer speed has improved, ease of use and power of CAD and 3D software has also increased exponentially. Architecture schools are facing the question of how reliant their students should be on computer technology [3][4]. In addition, what is the right software to facilitate the students’ artistic expression? Administrators and teachers have to make decisions based on the software learning curve, price and power. This paper is not intended to advocate the use of digital technology versus the manual approach in architectural education. I believe that we are passed that type of discussion. It is also worth noting here that in our department, most classes including design studios are using digital technology with the exception of very few classes. Following the advent of computer technology and CAD in the early Eighties, a number of architects resisted embracing AutoCAD because it was regarded either as a drafting tool or as too complicated; i.e. an engineering software. Around that time, two packages for architecture came to the market: ArchiCAD and later Architrion which were both on the Apple Mac platform. These packages presented two different approaches to architecture. ArchiCAD, developed by, and for architects, came to the rescue of those who resisted AutoCAD. Simply put, the program was easy to use, intuitive and built on a set of library

* Corresponding author: Email [email protected]

_______________________________________1Architecture, Interior design and Urban Design2The UAE University was created 1978


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blocks. It provided the tools of a CAD program and allowed the ability to work in a 2D environment and view the results in 3D. The user could also edit in 3D and see the changes reflected in plan and elevation. In addition, the cost of the project could be calculated at any time. Architrion, however, relied on using 3D to generate 2D drawings. The process involved modeling the 3D design as far as possible and then extracting 2D information for use in CAD drawing programs. 2. GENERAL BACKGROUND The Department of Architectural Engineering at the UAE University offers a five year Bachelor program. In the first two years, the students are required to take broad university courses (first year) and College of Engineering courses (second year). After this, the students spend three years in the Architecture Engineering program. During their first year the students are required to purchase a laptop computer that they will use during their time at the university. At the moment the system is an Intel 4, running Microsoft Windows XP. The University encourages active use of computer technology in the classroom and promotes laptop teaching through the use of the Blackboard system. Prior to joining the department, the students take two AutoCAD classes in addition to Microsoft Office Suite (Word, Excel, PowerPoint, and Access). While in the Department of Architecture, the students can take up to two elective courses respectively on Form-Z, 3D Studio Max and/or ArchiCAD. In addition, during their five design studios, the students also learn and use at least one of the following: AutoCAD, ArchiCAD, Form-Z, SketchUp or 3D Studio Max. With the exception of AutoCAD, which is officially taught by the university, the rest of the software is left to the faculty to select. Over the years this situation has led to many students being proficient in more than one software package. In the case where students rely on a single package, this software is ArchiCAD. ALHOSN University offers four year programs in Urban Planning, Architecture, and Interior Design, which started five, four and three years ago respectively. In the first year of the bachelor programs above, the students are required to take broad university and College of Engineering general courses. Afterwards the students spend three years in their respective program. In general, students take two required courses, one in AutoCAD and another in 3D Studio Max. In addition to the above packages, students also use SketchUp. Mastering software is not based on learning commands alone. Only through heavy use in trying to realize a complete project will the student realize the advantages and limitations of the software he or she is using. A less tangible, but very important aspect is the intuitiveness or elegance of the user interface.

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3. THE EMERGING STRATEGY: A FLEXIBLE WORKFLOW Allowing faculty to choose and teach software that they feel is appropriate for the task and student learning level has led to a positive situation. In many cases a de facto workflow has evolved with the following characteristics:

SketchUp is ideal for conceptual modeling. AutoCAD for 2D drafting, ArchiCAD and/or Revit for 2D and 3D drafting and design development, Form-Z or 3D Studio Max for advanced 3D modeling∗, 3D Studio Max for rendering and animation.

3.1 Software Overview There is a tacit understanding among faculty that the major focus in the program is and should be the architectural design process; i.e. the development from conceptual stage to presentation. Over the years SketchUp has emerged as the program to learn and use first. It is an easy and fast tool with which the student can begin his or her project, and at a later stage, choose between AutoCAD and / or ArchiCAD for final drawings and modeling (depending on architectural tasks and/or students’ needs). SketchUp SketchUp makes 3D visualization an easy endeavor. It provides the student with tools to communicate his/her thoughts in a direct manner. The program is also powerful and easy to learn. It is the ideal package for First Year architectural students as it helps them understand the design process. For others it is well suited for starting the design concept. Even experienced students use it to design and communicate their ideas quickly. SketchUp allows the student to learn quickly how to put together a 3D mass and to import the result into a CAD program such as AutoCAD or ArchiCAD. In one of those programs the students quickly and easily turn the imported SketchUp sections and mass into plans, elevations and sections. In fact, no major transfer problems have been experienced, and the overall results of using SketchUp have been very encouraging. AutoCAD AutoCAD is a popular CAD program commonly used for engineering and architectural applications. For 2D work, the program is probably the best option available. Users like it for its flexibility, user base, customization, compatibility, and support network. The supported formats of .dwg and .dxf are the standard for moving files between almost all 2D and 3D applications. In fact most architectural and construction firms use this software; and many 3rd party plug-ins are available for it.

∗ Or Rhinoceros 3D or Maya for 3D modeling and rendering and animation (for 3D and Maya)

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In the past, many architectural students felt that AutoCAD was sterile and mechanical; a product more tuned to engineers - with add-on packages for architects. Designing in 3D in the present version, AutoCAD 2009 has been made easier; but still it is not as smooth and powerful as in other applications such as ArchiCAD. ArchiCAD For 2D and 3D combination, ArchiCAD is probably a good compromise solution. It is easy to use, and targets architects and other designers. Since its beginning, ArchiCAD has been "by architects, for architects" so the interface is more tuned to how architects think and work. It uses a single building file and object technology concept known as Virtual Building. The user of ArchiCAD generates all required 2D and 3D output from a single file. Users work and edit directly in both 3D and 2D. Until very recently (Version 11) ArchiCAD had two drawbacks. The first was the look of the 2D drawings and the second was that printing was accomplished from a separate program; Plot Maker. Faculties have complained about the quality of ArchiCAD‘s printed 2D output especially elevations and sections. This particular point really depends on the student/drafter rather then the program. It is true however for novice students with the default settings that the quality is limited. ArchiCAD do however provide for control of line weights, fills, and text just as in AutoCAD. The second problem associated with printing from an external provided program, a serious one provided extra headaches for the teaching staff. Graphisoft in their last release has solved this issue. Revit Autodesk Revit, while relatively new to the architecture scene in its present incarnation, is actually an evolution of European Building Information software from the mid-nineties. One of its strengths is its excellent handling of the .dwg format. Revit is much more like ArchiCAD than AutoCAD, but some of the features are less mature while others are more advanced. Revit is relatively sterile windows typical interface. As a marketing strategy Autodesk is selling AutoCAD and Revit bundled together for the price of either of these purchased separately. Form-Z∗ Form-Z is the result of the efforts of a group of software developers associated with the Architectural School at The Ohio State University. Form-Z is a general purpose solid and surface modeler which has proved to be an effective tool for architects and urban designers. Form-Z is a powerful tool for visualizing any conceivable space or mass. The downside of this power and flexibility is a cumbersome interface. Form-Z lacks rendering and animation capabilities.

∗ As of 2010, Ohio State University has dropped development of form-Z.

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3D Studio Max 3D Studio Max is a 3D modeler, render and animation program currently owned by AutoDesk. It is used by the film, television and computer game industries. Over the years 3D Max has appealed widely to architectural visualizers and computer artists. Today a majority of architectural firms world wide use this software for modeling and rendering. With 3D Max, the student has access to powerful tools. 3D Max is well qualified to satisfy all of the user’s needs as a modeler and renderer but it requires a substantial amount of time and effort to master. In general, however, it would be more productive over time to limit CAD programs to 2D work since these programs are far less developed and flexible than programs dedicated to 3D modeling. CAD programs are rigid due to their tie to its 2D aspect; therefore it becomes very tedious to work in. In fact, based on experience, the suggestion is to stick to 3D programs (SketchUP, 3D Studio Max, etc.) and simply export line drawings such as sections and plans to CAD programs for editing and finalizing. In terms of the workflow mentioned earlier, with the inclusion of Form-Z at one step and 3D Studio Max as another, a good suggestion is to stick with one strong, powerful 3D software as it will allow you to both model and create incredible renderings. Rendering capabilities in programs such as Rhino and 3D Studio Max can be extended by using plug-ins such as V-ray, flamingo, etc. Workflow then becomes simpler and more fluid. SketchUp if you want quick initial conceptual development, or immediately start with stronger 3D software to:

1- Develop design in 3D, 2- Extract sections/plans from model, 3- Import into CAD to touch-up and adjust detail drawings, 4- Use 3D software to render from a model that is already built, 5- Export renderings to Photoshop if needed for further touch-ups, 6- Take drawings, renderings and diagrams into your choice of software for presentation

preparation (InDesign, Illustrator, Photoshop). 7- The last step is to finalize boards.

Of course in the workflow just mentioned, initial stages of conceptual design are not limited to 3D software. In fact we must/can include drawings, sketches, and physical sketch model. 3.2Workflow Case Studies The following are two case studies which demonstrate work done using multiple software applications. Since a picture is worth a thousand words, the captions underneath the following pictures should be enough to convey some of the students’ ad hoc strategies.


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Case study 1

Figure 1. AutoCAD drafting overlay of scanned freehand concept sketch.

Figure 4 SketchUp massing study from the imported AutoCAD .dxf file.

Figure 2 Revised AutoCAD plan in response to SketchUp massing. Original Plan shown beneath and new plan super imposed.

Figure 5 Final AutoCAD single line site plan.

Figure 3 The imported final AutoCAD plan made into double line in ArchiCAD. The final project next to existing on the left.

Figure 6 An initial 3D view of ground floor in ArchiCAD.

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Figure 7 Complex 3D element modeled in Form-Z and brought into ArchiCAD as a dxf file

Figure 8 Rendering in ArchiCAD showing the element imported from Form-Z.

Figures 9 & 10 Further ArchiCAD perspective renderings.

Figure 11 2D site plan graphics generated in ArchiCAD.


Figure 9 Figure 10

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Case study 2

Figure 12 Freehand concept sketch. Figure 13 Evolution of SketchUp massing models.

Figures 14 & 15 Views of the ArchiCAD final projects.

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Figure 15

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4. CONCLUSIONS: WHICH IS BETTER, CHOCOLATE OR VANILLA? An individual’s choice of programs all depend on their requirements for use and the specific project at hand. Learning several CAD and 3D software packages actually provides the students with more freedom to visualize and express their ideas. They use the tools that they feel more comfortable with. Some students like to experiment, and mastering several programs translates into different possibilities to achieve a better project. For others, using very few, even only one program, such as ArchiCAD, is everything they need to be able to achieve good results. The faculties in architecture, like their counterparts in the professional field, are divided into mainly two groups. One group is quite happy with the use of one package and/or the combination of two packages. The second group would put more emphasis on the students learning a more comprehensive spectrum of applications. Most of the faculty members use and encourage the use of computer technology in the classroom. The difference is in the degree in which they encourage the student to rely on the use of computers. Based on experience, no software does it all [5]. For the students, it is important to have access to several choices; a practical approach would be to use a variety of packages at different design phases. You may ask which software? For AutoCAD users an advance path would be to move to Revit – the function is similar to ArchiCAD. The drawback of Revit for students is a weak rendering capability and an orientation to large multi-user projects. Barring completely new developments, ArchiCAD will remain the best combination of 2D, 3D and simple rendering capabilities for the student user. Form-Z is certainly the most advanced modeler oriented specifically towards architecture, while 3D Studio Max truly has no limits in regards to modeling (but is fairly complicated to realize its full potential). SketchUp, despite limited modeling power compared to Form-Z, has gained a truly remarkable popularity among architecture students and professionals based on its interface, ease of use, speed and small learning curve. For rendering and animation, 3D Studio Max will remain the software of choice since its capabilities in these areas are unchallenged by any of the other software discussed. It is interesting to note that the best software for architecture students, ArchiCAD, SketchUp and Form-Z were all developed specifically for architects. In the near future, students of architecture with strengths in programming will be involved in the next software to push the limitations of present CAD and visualization software.


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5. REFERENCES

[1] Andreas Asperl.(2005) How to teach CAD Computer-Aided Design & Applications, Vol. 2, Nos. 1-4, pp 459-468.

[2] Tony Longson. Computers in Art an d Design Education — Past, Present and Future. http://old.siggraph.org/education/conferences/GVE99/papers/GVE99.T.Longson.pdf.

[3] Julio Bermudez & Kevin Klinger editors (2003). Digital Technology & Architecture - White Paper. Association for Computer Aided Design in Architecture ACADIA: 2003. http://www.acadia.org/ACADIA_whitepaper.pdf.

[4] Nickolas S. Sapidis & Myung-Soo Kim (2004) Editorial to special issue: CAD Education Computer-Aided Design Design. 36 1429–1430.

[5] Jules Moloney Moloney. 3D Game Software and Architectural Education (2001). http://www.ascilite.org.au/conferences/melbourne01/pdf/papers/moloneyj.pdf.

ACKNOWLEDGEMENTS The author wishes to thank all the students who over the years have demonstrated their excitement, eagerness to learn, and ingenuity in applying computer technology as it related to architecture. Special thanks to the students for their input for this paper and in particular to Mrei Al-Zouabi and Hashel S. Allamki for the case studies in this paper; respectively Case #1 (design project for Architectural Studio 4) and Case #2 (design project for Architectural Studio 2). My apologies to students who provided work examples which I couldn’t include due to space limitation. My thanks to faculty colleagues at the College of Engineering and Applied Sciences at ALHOSN University and at the College of Engineering at UAE University who provided me with their personal views on the use of CAD and 3D the curriculum. The author also wishes also to thank Colin Weston and Arch. Mohamed Nazmy for their contributions.

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