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Proceedings of the

Inaugural Australian

YOUNG

RESEARCHERS’

CONFERENCE

Friday 8 December 2017 At The University of Queensland

Contents

Page 2

The Institution of Structural Engineers | Proceedings of the Inaugural Young Researchers’ Conference | 8 December 2017

Welcome

3

Programme

4

Speaker

5

Judges

6

Synopses

01 Alexander Mainey – Mechanical and artificial improvement of nailplate connected timber truss joints

7

02 Ali Umran Al-saadi – Axial behaviour of Fibre Reinforced Polymer (FRP) composite

tubes 9

03 Ali A Mohammed – Prefabricated composite jacket for repairing of damaged concrete

columns 11

04 Andrea Lucherini – Effectiveness of thin intumescent coatings used for fire-safe steel

structures 13

05 Carmen Gorska – Self-extinguishment of Cross Laminated Timber (CLT) in Multi-

Scale Compartment Fires 15

06 Duy Huu Nguyen– Early-age cracking in Concrete Structures – Mechanisms and

Control 16

07 Hong Zhang – Hencky bar-chain model for buckling and vibration analyses of beams

and arches 19

08 Huizhong Xue – Load Transfer and Collapse Resistance of RC Flat Plates under

Interior Column Removal Scenario 21

09 Husam Alsanat – Web crippling behaviour of aluminium lipped channel sections

under two flange load cases 22

10 Mahmoud Alrsai – Parametric Study on Buckling of Pipe-in-pipe Systems under

External Pressure 24

11 Mateo Gutierrez Gonzalez – Design of fire safe bamboo structures 26 12 Mengzhu Diao – Post-Punching Mechanism of Slab-Column Joints Subjected to

Upward and Downward Punching Shear Actions 28

13 M Imran – Fire Performance and Design of CFRP Strengthened and Insulated Cold-

Formed Steel Tubular Columns 29

14 Myuran Kathekeyan – Fatigue design of thin steel roof batten to rafter connections

under cyclic wind uplift loading 30

15 Nhat Minh Ho – Experimental and theoretical studies on three-side restrained

reinforced concrete walls 33

16 Nilakshi Perera – Section moment capacities of Hollow Flange Steel Plate Girders 35 17 Nima Talebian – Biaxial bending behaviour of cold-formed steel storage rack uprights 37 18 Thananjayan Sivaprakasam – Structural Performance of Aluminium Façade Mullions

under Wind Actions 39

19 Vinny Gupta – Exploring the Energy Distribution of Large Open Floor Plan

Compartment Fires for the Safe Design of Tall Buildings 41

20 Yousef Al-Qaryouti – Digital-Fabrication Structures for Prefabricated Infrastructure 43 21 Yuan Xu – Seismic Performance of Prefabricated BRBY with Moment-resisting and

Non-moment-resisting Beam-Column-brace Connections 45

22 Zameer Kalakada – Experimental Investigation on Recycled Glass Powder as a Pozzolanic Cement

46

Welcome

Page 3


A special welcome to the Inaugural Australian Young Researchers’ Conference (YRC). This

event has been held in the Institution of Structural Engineers Headquarter nineteen times

since 1988, and is a fantastic opportunity for PhD student or first year post-doctoral

researcher to present their research to industry representatives, academics and fellow

researchers.

The winner of this conference will be provided subsidy towards travelling to IStructE HQ in

47-58 Bastwick Street London to join the 20th anniversary of YRC on 10 April 2018, and give

a presentation of the research up-to-date.

To mark the 20th anniversary, the Institution will be joined by Sarah Prichard as keynote

speaker. Sarah was a joint winner in the oral category at the very first Young Researchers’

Conference in 1998. She has since completed her PhD on the response of concrete to

impact at Trinity College Dublin and has worked for BuroHappold for 16 years. Sarah is one

of the practice’s leaders in the field of building vibrations and dynamics and consults widely

in this area, particularly on mixed use, transport stations, sports structures, hospitals and

laboratories projects. She has recently been appointed a Partner of the firm.

The Australian YRC is an initiative from Professor K.F. Chung from The Hong Kong

Polytechnic University, Department of Civil and Environmental Engineering; who has

organised similar event in China this year. Professor Chung was meant to attend this

conference as a Keynote Speaker on “Effective Use of Hight Strength Q690 Steel in Building

Construction”, but sent his apology due to other commitments.

We, as the co-organisers, wish you all embrace the concept of carrying out research towards

some practical applications and add value to the knowledge of Structural Engineering. Enjoy

your participation and hopefully it is a rewarding one for all, whether as a winner or

otherwise.

Co-Organisers

Dr Peter Ho AM Dr Johnny Ching Ming Ho BSc, PhD, FIStructE, FIEAust, MICE, MHKIE, MPhil, PhD, MIStructE, MHKIE, MIEAust,

CPEng, RPEQ, JP(Qual) CPEng, NER, CEng

Programme

Page 4


Date: Friday 8 December 2017 Venue: The University of Queensland, St Lucia, QLD4072 Auditorium: Bulding #50, Hawkin Engineering Building, T203 Room A: Bulding #50, Hawkin Engineering Building, T103 Room B: Bulding #50, Hawkin Engineering Building, T105

Time Activities

8:30-9:00 Registration (Outside 50-T203)

9:00-9:20

Welcome (Auditorium)

(a) Representative from IStructE – Phil Latham, Qld Group Chair (b) Representative from UQ – Adjunct Prof Peter Ho AM (c) Adoption of Rules and Regulations

9:20-9:40 Introduction of Institution of Structural Engineers and routes to

Membership (by Research) (Past IStructE President Mike Fordyce)

9:40-10:00 DRAW UP PRESENTATIONS

Morning Tea

10:00-10:20 Presenter 1

(Room A, Panel 1) Presenter 2

(Room B, Panel 2)

10:20-10:40 Presenter 3


(Room B, Panel 2)

10:40-11:00 Presenter 5


(Room B, Panel 2)

11:00-11:20 Presenter 7


(Room B, Panel 2)

11:20-11:40 Presenter 9


(Room B, Panel 2)

11:40-12:00 Presenter 11


(Room B, Panel 2)

12:00-13:00 Lunch

13:00-13:20 Presenter 13


(Room B, Panel 2)

13:20-13:40 Presenter 15


(Room B, Panel 2)

Programme

Page 5


Time Activities

13:40-14:00 Presenter 17


(Room B, Panel 2)

14:00-14:20 Presenter 19


(Room B, Panel 2)

14:20-14:40 Presenter 21


(Room B, Panel 2)

14:40-15:10 Afternoon tea

Announcement of Panels 1 & 2 winners Draw up presentation ORDER for Panels 1 & 2 winners

15:10-15:50 Winners of Panel 1 & Panel 2 to present

(Auditorium)

15:50-16:10 Short break

16:10-16:40 Announcement of Winner

Award presentation and closing remarks (Auditorium)

16:40-18:00 Networking

(Foyer)

Speaker

Mike Fordyce BSc, MEng, FIStructE, FIEAust, CPEng

Mike Fordyce is a Chartered Structural Engineer with over 50 years’ experience in the fields of conceptual planning, project management, design and superintendence for building and engineering infrastructure projects; asset condition reports; feasibility studies; materials investigations; and development of building systems. Mike has worked in consulting engineering in the UK, USA and Australia, latterly with Kellogg Brown & Root (KBR) where he was a Principal Engineer, Project Director and Resource Group Leader for the Civil Structures group in Queensland. Mike served as National President of Concrete Institute of Australia in 1995-96 and he was elected the first non-UK based President of the

Institution of Structural Engineers for the session 2004-2005. In 2009 he was awarded the John Connell Gold Medal by the Structural College of Engineers Australia for his contribution to the structural engineering profession. Following his retirement from KBR in September 2011 he has maintained an active involvement in Structural Engineering through the IStructE Australia Regional Group.

Judges

Page 6


Dr Ron Blackwell BE(Hon 1), PhD, CEng, MIStructE, MIEAust, CPEng, RPEQ

Dr Ron Blackwell is a civil engineer with over 40 years experience as a practicing engineer in architectural, building and civil structures. He is currently self employed as a consulting engineer and an Associate Professor in the School of Civil Engineering at the University of Queensland. Ron has served on the

committee of the Institution of Structural Engineers, Australia Regional Group as well as Structural Branch Qld of Engineers Australia for number of years.

Dave Hargreaves BSc (Hons), MS, AIStructE, MIEAust, NER, CPEng

Dave Hargreaves graduated from the University of Natal in Durban, South Africa with a Cum Laude Honours degree in Civil Engineering; and has a Masters Degree in Structural Engineering and Structural Mechanics from the University of California at Berkeley, California. He has over 30 years’ experience in

the building structures, construction engineering and industrial structures environments, with involvement in a wide variety of projects in Australia, Asia and Africa. He has worked on a broad spectrum of contracts including high-rise, commercial and residential developments, hospitals, shopping centres and industrial facilities, stadia and infrastructure developments. He has served on the committee of the Institution of Structural Engineers, Australia Regional Group, since its inception.

Toby Hodsdon MPhil, PhD, MIStructE, MIEAust, MHKIE, NER, CPEng

Toby is a Principal Structural Engineer at Bligh Tanner and has 14 years’ experience in the design, construction and maintenance of building structures. He has successfully delivered a wide range of projects in UK, Australia and Middle East to build a track record of developing strong

collaborative relationships and applying innovation to design. His specialism is in the field of engineered timber, having several glulam structures to his name and an early adopter of CLT in Queensland. He also has experience of designing with other sustainable building materials such as rammed earth and lime concrete. Toby has conducted research into these materials, and was the recipient of the IStructE Rowen Travel Award 2003 and IStructE Young Researcher Grant 2002.

Phil Latham BEng (Hons), BEngSc, MSt(IDBE) (Cantab), MIStructE, MIEAust, CEng CPEng RPEQ

Phil is a Chartered Structural engineer with 18years experience with projects in the UK, UAE, Europe and Australia. Phil has experience with a wide range of building typologies particularly transport orientated and public buildings. Phil’s key achievements include Ferrari World in Abu Dhabi, Belwind Offshore Wind Farm,

Brugge and Moreton Bay Rail Link, Brisbane. Phil is a Principal at Robert Bird Group and is currently the Vice-Chair of the Institution of Structural Engineers, Australia Regional Group and Chair of the Institution of Structural Engineers, Queensland Group.

Joseph Tam BSc, PGDip(PR), MIStructE, FIEAust, MICE, MHKIE, CPEng, RPEQ

Joseph is the Principal Supply Planner of Seqwater responsible for supply options development and master planning to meet long term water security needs for South East Queensland. From 2005 to 2013, Joseph took charge of the regional operations, including control systems, for water and sewerage networks assets for Ipswich Water and then Queensland Urban Utilities.

Joseph was experienced in disaster recovery, incident management, asset protection/relocation of water and sewerage assets. During his early career in Hong Kong and Australia, Joseph designed and supervised construction of bridges; buildings, retaining structures, roads and drainage, site formation and foundation works. Joseph served as the Chair of the Structural Branch Qld of Engineers Australia from 2015 to 2017.

Dr June Zhang BEng, PhD, FIEAust, RPEQ

Dr June Zhang has well over 20 years of Civil & Structural engineering experience, in the areas of mining, coal seam gas, industrial and commercial sectors; including design and detailing process plants, smelters and refineries, coal seam gas plant and pipeline, hydro power station. She is

currently a Principal structural engineer working with Worleyparsons over 8 years. She has been working on many big projects in Australia and cross the world. Last 4 years working on the Nyrstar project, FIFO basis, June experience and technical skills across all facets of the Expansion project has added significant value to the project. Prior to this role, she was working with Rio Tinto, Bechtel and Ausenco.

Mechanical and artificial improvement of nailplate connected timber truss joints

01 Alexander Mainey

Griffith University

Page 7


Project background, objectives and goals This project, in a collaboration between Griffith University, the Department of Agriculture, Forest and Fisheries (DAF) and an industry partner, Multinail, aims to investigate, understand and develop an improved nailplate design. These nailplates made from 0.95 mm nominal thick galvanised steel are used to connect timber members together commonly used for residential timber trusses. The performance of the nailplate and the joint is a function of the nailplate size, timber strength, loading points and the style of the teeth. A recent investigation by the CSIRO found issues of in-service nailplates where the nailplate was observed to have backed out from the parent timber. The significance of this is that a 1mm backout (~10% of the tooth length) can lead to a 25% reduction in joint strength (Paevere, et al. 2008). An example of the backout is shown in Figure 1. This backout, caused by the sorptive nature (shrink and swell) of timber due to external climatic conditions, is not well understood and prevents the effective use of nailplates in external environments. Ultimately, this research aims to re-design the tooth profile to either: i) prevent the backout from occurring or ii) have the plate retain its strength after some backout thus enabling a wider and more efficient use of timber trusses. While it is known that the nailplate backs-out due to the repeated shrinking and swelling of the timber, the confining conditions and internal stresses of the timer that cause this backout are unknown. Therefore, as part of this project, the mechanisms that cause said backout are to be investigated.

Fig 1 Observed tooth withdrawal witing a tension splice joint (P. Paevere, M. Nguyen et al. 2008)

Adopted methodology The project has been broken down into three main approaches: 1) Investigation of alternate tooth designs

considering a purely mechanical approach (reforming the tooth profile) and an adhesive approach. Single teeth (called nails), representative of the nailplate tooth, were laser

cut and pressed into small timber samples (shown in Figure 2). The samples were then steamed for 2 hours and dried for 19, constituting one wetting and drying cycle. The backout of each nail, with respect to its initial position was recorded. In addition, the withdrawal force of each design was recorded at 0, 1, 2, 5 10, 20 and 30 cycles.

Fig 2 Specimen with single nails 2) Understanding the mechanisms causing backout

was investigated through the moisture cycling of single nails in timber while monitoring the samples continuously for 40 days. The samples were monitored using two cameras, thereby allowing for a digital image correlation (DIC) to be made. The average mass of the samples, the applied temperature and humidity, and the surface strain recorded by the DIC are known.

3) From the single tooth investigation, two designs,

one mechanical based and one adhesive based, will be refined and incorporated into a full nailplate. Parallel and perpendicular joints will be made from these design and subject to an accelerated moisture cycling regime. After each cycle, the backout of the nailplates will be recorded followed by the testing of each joint. The results will yield the rate of backout of each design and the rate of joint strength degradation due to moisture cycling.

Findings and application of results With an eye on the compatibility of the designs for industrial application (all new design concepts capable of being manufactured in a similarly efficient process as that used today), three new designs were investigated using single nails, one adhesive design (G) and two mechanical based designs (MD1 and


MD2). The backout of each design was recorded and compared to the existing or base design (B). The results are shown in Figure 3. The adhesive design proved to stop all backout while the mechanical designs stopped backing out after approximately 10 cycles.

Fig 3 Recorded backout of 4 different designs after each moisture cycle The data recorded throughout the DIC investigation will allow the mechanisms causing backout to be identified. Preliminary analysis of the results is in shown in Figure 4 where the distance between the nail and the surface of the timber is plotted on top, while the average moisture content is plotted below. A numerical model is currently being developed to reproduce the observed nail backout versus time. The model is based on the research published by Nguyen (2008) and will be used to fully understand the nailplate backout mechanisms.

Fig 4 Recorded backout measured by DIC plotted with the average moisture content

This project not only aims to deliver a new design which can prevent sorptive-driven backout, but also to further the understanding of the mechanisms diving the backout.

References Atkins, W. B. (1962). Connector plate, Google Patents. Correllated Solutions. 2017. Vic-3D User Manual. www.CorrelatedSolutions.com Groom, L. (1995). Effect of Moisture Cycling on Mechanical Response of Metal-Plate Connector Joints With and Without an Adhesive Interface, Res. Pap. SO-291. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station. 30 p. Paevere. P, Nguyen. M, Syme. M, Leicester. R. 2009. Nailplate Backout – is it a Problem in Plated Timber Trusses. FWPA Limited Paevere. P, Nguyen. M, Syme. M, Leicester. R. 2008. Nailplate Backout – is it a Problem in Plated Timber Trusses. Proceedings of the WCTE2008, Japan Nguyen. M, Paevere. P, Leicester. R, Syme. M. 2008. Models for Prediction of Microclimate and Timber Moisture Content within the Building Envelope. Proceedings of the WCTE2008, Japan StandardsAustralia (2001). Timber—Methods of test for mechanical fasteners and connectors—Basic working loads and characteristic strengths. Sydney, Australia, Standards Australia.

Further Information Alexander Mainey ([email protected])

http://www.correlatedsolutions.com/

mailto:[email protected]

Axial behaviour of Fibre Reinforced Polymer (FRP) composite tubes

02 Ali Umran Al-saadi

University of Southern Queensland

Page 9


Project background, objectives and goals The use of FRP tubes to enhance the performance of concrete columns has been extensively researched in the last decade. The main feature of this kind of FRP tubes is that most fibres are oriented towards the hoop direction to provide effective confinement. Pultruded FRP tubes are manufactured through pultrusion process where the majority of fibres are oriented towards the axial direction. Although pultruded FRP tubes can resist reasonable compressive load, they can not normally reach their potential capacity. This is mainly because they have low axial stiffness and the failure will be governed by instability conditions due to buckling (Barbero & Raftoyiannis 1993; Correia et al. 2012; Nunes et al. 2016; Ragheb 2017). As the low longitudinal stiffness does not allow an axial member to utilise the full capacity of pultruded FRP tubes, this research intends to investigate the possibilities of improving the axial load capacity of pultruded tubes by filling with a suitable type of concrete. Concrete infill will enhance the stiffness of the FRP tubes while providing support to tube against buckling. Different types of concrete have been used to fill FRP tubes to investigate how the stiffness of concrete can augment the axial behaviour of filled columns. Two types of normal concrete and two types of lightweight perlite concrete were used to fill FRP tubes. Different types of FRP tubes having square and circular shapes with different fibre orientation were selected in this study because the compressive behaviour of pultruded FRP-concrete tubes depends on the angle of the fibre orientation and the effectiveness of the FRP confinement.

Adopted methodology Research methodology of this study is summarized as follows (Fig.1):

Experimental investigation- Material characterisation and axial concentric tests have been executed for the column specimens.

Numerical simulation- Develop a simulation method to predict the behaviour of column specimens (hollow and filled) by using STRAND7 finite element program. Numerical investigation is validated using the experimental results.

Parametric study- Predict the behaviour of filled FRP profiles with a range of different parameters such as concrete modulus, FRP wall thickness and the fibre orientation.

Design recommendations- The results of the experimental, numerical and parametric studies will determine the effect of research parameters on the axial behaviour of filled pultruded FRP. This will lead to design recommendations for filled pultruded FRP tubes to be used in column applications.

Figure 1: Research methodology

Findings and application of results The outcomes of the study so far are summarized as follows:

The degree of improvement in the compressive behaviour of concrete filled pultruded FRP is influenced positively as the elastic modulus of infill concrete increases especially when the FRP tube has an adequate hoop stiffness. The failure modes of FRP tubes in square shape were changed due to filling with concrete from either splitting at mid-height followed by the buckling to corner splitting at one end of the column or from local buckling to crushing at the end followed by the corner splitting. The failure modes of the circular FRP tube had also altered from circumference splitting at one end of the hollow column to be crushing at one or both


ends followed by longitudinal splitting of the filled column.

FRP tubes filled with perlite concrete did not show a rapid drop in the load carrying capacity after reaching the peak value compared with those filled with normal concrete. Better ductile behaviour will avoid a sudden collapse in the column.

When FRP tube has a sufficient stiffness in the transverse direction, the improvements in the axial behaviour of pultruded FRP-concrete tubes can be observed. The degree of improvement depends on the properties of concrete, fibre orientation of the pultruded FRP tubes and the shape of a column.

References Barbero, EJ & Raftoyiannis, IG 1993, 'Local buckling of FRP beams and columns', Journal of materials in civil engineering, vol. 5, no. 3, pp. 339-55. Correia, M, Nunes, F, Correia, J & Silvestre, N 2012, 'Buckling behavior and failure of hybrid fiber-reinforced polymer pultruded short columns', Journal of Composites for Construction, vol. 17, no. 4, pp. 463-75. Nunes, F, Correia, JR & Silvestre, N 2016, 'Structural behaviour of hybrid FRP pultruded columns. Part 1: Experimental study', Composite Structures, vol. 139, pp. 291-303. Ragheb, WF 2017, 'Development of closed-form equations for estimating the elastic local buckling capacity of pultruded FRP structural shapes', Journal of Composites for Construction, vol. 21, no. 4, p. 04017015.

Further Information Ali Alsaadi

([email protected])


Prefabricated composite jacket for repairing of damaged concrete columns

03 Ali A Mohammed

University of Southern Queensland

Page 11


Project background, objectives and goals In the last two decades, fibre reinforced polymer (FRP) composites have become extremely versatile and popular construction materials for strengthening and rehabilitating damaged infrastructures, especially those that are located in harsh environments such as marine or mining areas [1-3]. Recently, a new type of FRP composite jacket with an innovative joining system for repair of structures has been developed (Figure 1). The novelty of this strengthening system is that it is quick and safe to install due to the easy-fit and self-locking mechanical joint. It works by wrapping the FRP jacket around the damaged structure and filling the annulus with a water displacing grout. This paper presents the development of this new type of FRP composites jacket and evaluation of its efficiency as a strengthening system for deteriorating and structurally deficient structures. The behaviour of large-scale concrete columns with simulated steel corrosion defect and repaired with the novel composite jacket was investigated. The results showed that the provision of the FRP jacket restored the axial capacity of concrete columns with 25% and 50% corrosion damage up to 99% and 95%, respectively. The successful completion of this research has resulted in several applications of this novel FRP jacket in repairing deteriorating bridge piers (Figure 2).

Fig 1 Novel FRP Jacket [4]

Fig 2 Deteriorated bridge piles repaired with the novel FRP jacket [5]

Adopted methodology The methodology of this study can be summarised into four main stages: 1) Characterisation of the joint and composite jacket

material to ascertain their mechanical properties. The constitutive material behaviour was used as material input in the finite element modelling and provided a better understanding on the column’s behaviour repaired with a jacket.

2) Determination of the most appropriate infill material that can effectively utilised the distinct properties of FRP jacket. For this purpose, three different types of infills were considered: (i) concrete-grout infill (ii) shrinkage compensating cementitious-

grout infill, and (iii) epoxy-grout infill.

3) Evaluation of the efficiency of the FRP jacket in repairing damaged concrete columns. Four columns (1m height and 250 mm diameter) with different level levels of simulated steel corrosion damage (Figure 3) were tested. The first and second columns were prepared with no damage and 50% steel corrosion damage, respectively. The third and the fourth columns were prepared with 25% and 50% steel corrosion damage, respectively, and repaired with 3 mm thick and

450 mm diameter jacket.

C1: 8-16 mm ϕ C2: 4-16 mm ϕ

C1: 6-16 mm ϕ C2: 4-16 mm ϕ

Fig 3 Columns specimens’ configuration


4) Finite element simulation of the behaviour of damaged concrete columns repaired with the FRP jacket. The model is validated with the experimental results and used in parametric study to investigate the effect of varying the level of damage, grout thickness and concrete compressive strength.

Findings and application of results The successful completion of this research is going to:

Provide a more in-depth understanding on the axial behaviour of damaged concrete members repaired with the FRP jacket.

Present an evaluation about the FRP jacket effectiveness in repairing deficient structures.

Create opportunities for construction companies, asset owners and transport authorities to highly consider the use of this technology for strengthening and rehabilitation of deteriorating and structurally deficient structures.

References [1] R. Lopez-Anido, A.P. Michael, T.C. Sandford, Fiber Reinforced Polymer Composite-Wood Pile Interface Characterization by Push-Out Tests, Journal of Composites for Construction 8(4) (2004) 360-368. [2] M. Ehsani, FRP super laminates present unparalleled solutions to old problems, Reinforced Plastics 53(6) (2009) 40-45. [3] P. Vijay, P.R. Soti, H.V. GangaRao, R.G. Lampo, J.D. Clarkson, Repair and Strengthening of Submerged Steel Piles Using GFRP Composites, Journal of Bridge Engineering (2016) 04016038. [4] Joinlox™, PileJax™ – Pile Repair Jackets, 2014. http://www.joinlox.com/pilejax/. [5] J. Solan, USQ, Joinlox collaborate on prefabricated composite repair system, Composites World, 2017.

Further Information Ali Mohammed ([email protected])

http://www.joinlox.com/pilejax/


Effectiveness of thin intumescent coatings used for fire-safe steel structures

04 Andrea Lucherini

The University of Queensland

Page 13


Project background, objectives and goals Nowadays, thin intumescent coatings are the dominant fire safety solution for protecting structural steel systems during fire. During heating, intumescent coatings swell to form a low density, highly insulating foamed char that prevents the steel load-bearing elements from reaching critical temperatures that can cause structural instability and possibly progressive failure. Traditionally, the fire performance of thin intumescent coatings is based on compliance to the standard fire resistance test in furnace, where coated steel samples are tested in accordance with the standard fire curve. Numerous researchers have emphasised the relevance of the heating conditions on the intumescent process and the overall effectiveness of the reactive fire protection system. Prior studies have shown that a slow growing fire (as those observed in large open plan spaces) may result in an incomplete swelling activation of the intumescent coating, or even in melting and/or delamination of the coating. Nevertheless, compliance across various industries (e.g. built environment, oil & gas industry) is limited to the response of the coatings to rapid growing fires and, despite developments to date, the fire performance of intumescent coatings subjected to a range of potential fire scenarios is still not fully comprehended. In particular, the influence of the heating conditions on the expansion and insulating properties must be understood before current models and design guidelines are applicable for the wide range of potential fire scenarios.

Adopted methodology The current research project intends to contribute towards a knowledge-based fire safe design of steel structures protected by thin intumescent coatings. In particular, this aims at gauging a comprehensive understanding of the complex thermo-physical response of reactive coatings exposed to various heating conditions. Within the scope of the work described herein, steel plates coated with a commercially available thin intumescent coating are tested using a novel fire test method (Fig 1).

Fig 1 Schematization of the experimental setup The test apparatus, known as Heat-Transfer Rate Inducing System (H-TRIS) consists on a high-performance radiant panel coupled with a computer-controlled linear motion system. The test method allows for direct and independent control of the thermal boundary conditions imposed on the test samples by controlling the relative position between the exposed test surface and the radiant burner. The test samples are exposed to several time-histories of incident heat flux. High density and precision thermal sensors are placed inside the reactive char structure in order to gauge the in-depth temperature distribution inside the expanding coating (Fig 2). In this way, it is possible to accurately investigate and model the heat transfer process within thin intumescent coatings exposed to a wide range of potential heating conditions.


Fig 2 Quasi-steady in-depth temperature profiles of expanded intumescent coatings exposed to: a) 25 kW/m2; b) 40 kW/m2; c) 55 kW/m2 (after 60 minutes of fire testing).

Findings and application of results This understanding will allow for the identification of the most onerous fire conditions that can yield an ineffective performance of the thermal barrier provided by intumescent coatings. The main outcome of this work will be to provide the basis for a new design framework that explicitly evaluates the fire performance of thin intumescent coatings, taking into account all the main factors governing the effectiveness of the intumescent coatings.

Further Information Andrea Lucherini ([email protected])

References Wang L., Dong Y., Zhan D., and Zhang C. Experimental study of heat transfer in intumescent coatings exposed to non-standard furnace curves. Fire Technology, vol. 51, no. 1, pp. 627-643, 2015. Wang L., Dong Y., Zhan D., and Zhang C. Experimental study of heat transfer in intumescent coatings exposed to non-standard furnace curves. Fire Technology, vol. 51, no. 1, pp. 627-643, 2015. Elliott A., Temple A., Maluk C., and Bisby L. Novel testing to study the performance of intumescent coatings under non-standard heating regimes. Fire Safety Science – Proceedings of the 11th International Symposium, University of Canterbury, New Zealand, pp. 652-665, 2014. Zhang Y., Wang Y.C., Bailey C.G., and Taylor A.P. Global modelling of fire protection performance of intumescent coating under cone calorimeter heating conditions. Fire Safety Journal, vol. 50, pp. 51-62, 2012. Lucherini A., Giuliani L., and Jomaas G. Experimental study of the performance of intumescent coatings exposed to standard and non-standard fire conditions. Fire Safety Journal, vol. 95, pp. 42-50, 2018.


Self-extinguishment of Cross Laminated Timber (CLT) in Multi-Scale Compartment Fires

05 Carmen Gorska


Page 15


Project background, objectives and goals Cross Laminated Timber (CLT) is an engineered timber product that has recently awaken the interest of the construction industry. Due its convenient strength to weight ratio, manufacturing process and its appealing aesthetics - industry and government entities started to push towards building with CLT. Moreover, the interest concentrates in leaving the CLT structure exposed (i.e. the timber is not protected/encapsulated by any plaster board or other non-flammable materials). This scenario leads to a new fire hazard in the built environment. Engineers are facing now a problem where the fuel load is much greater and the structure itself is subjected to a thermal decomposition process. The loss of the effective cross-section challenges the structural integrity during the fire, and the increased external plume threats the vertical compartmentation in high-rise timber buildings, thus facilitating vertical fire spread. These examples represent how easily the fire strategy can be unsuccessful for this kind of buildings. This research aims to quantify these new fire hazards by comparing medium-scale compartment fires with exposed CLT versus a non-flammable structure. Additionally, a scaled-up compartment fire with exposed CLT was conducted in Brisbane (Australia) in 2016. Several researches have been studying the phenomenon of self-extinguishment of timber. Self-extinguishment stands for the ability that timber has to stop burning without external intervention. This is an intrinsic quality of timber since the heat flux supplied by the flames from the combustion is

smaller than the heat losses �̇�𝐹′′ ≤ �̇�𝐿

′′ [1]. Therefore, timber can only keep burning if an external heat flux

is applied �̇�𝐹′′ (in a compartment fire that could be

the burning furniture or the hot walls radiating to the exposed timber member). Hence, understanding the variables that may allow self-extinguishment of timber in a compartment fire is the key factor to be able to design such buildings and therefore, to use self-extinguishment as part of the design fire safety strategy.

Adopted methodology The compartment variables that are studied in this work are: (1) the fuel load, which affects the duration of the fire; (2) the opening factor, which controls the oxygen inflow into the compartment; and (3) the configuration of the exposed CLT surfaces, which influences the radiative heat exchange between the compartment surfaces.

At present, there are three criteria to define self-extinguishment: (1) a critical external heat flux, (2) a critical temperature gradient within the timber and (3) a critical mass loss rate (MLR) [2, 3]. Several researchers have been studying these criteria by bench-scale testing. Therefore, this project focuses on measuring and estimating these criteria for structural CLT members in medium- and large-scale compartment fires and comparing the results with the results at a bench-scale.

Findings and application of results The work done up to date shows that the external heat flux to the façade can be as much as 2.5 times larger when having exposed CLT, the temperatures inside the compartment remain unaltered, and that gauging the external heat flux into surfaces inside the burning compartment is very complex. Thus, the obtained results present a significant inconsistency with previous work. The planned future work embraces an analysis of the MLR and temperature gradient criteria, a study of the energy balance in the compartment, a better characterization of the façade plume and the radiative feedback between several exposed CLT walls.

References [1] Drysdale, D., An introduction to fire dynamics. Vol. 3rd. 2011, Chichester, England: John Wiley & Sons. [2] Emberly, R., et al., Self-Extincion of Timber. Proceeding of Combustion Institute 2016. [3] Alastair Barlett, R.H., Luke A. Bisby and Barbara Lane, Auto-Extinction of Engineered Timber: The Application of Firepoint Theory in Interflam. 2016: At Royal Holloway College, Nr Windsor, UK.

Further Information Carmen Gorska Putynska ([email protected])


Early-age cracking in Concrete Structures – Mechanisms and Control

06 Duy Huu Nguyen


Page 16


Project background, objectives and goals

Fig 1 Early-age cracking in restrained concrete, adopted from Bjøntegaard [1] Cracking in young concrete remains a persisting problem worldwide that causes serious economic and sustainability impacts. Such cracking risk develops from the very first days after placement, when tensile stresses are induced in concrete due to restrained deformations. Unless effectively accounted for, these tensile stresses can either (i) Cause cracking (i.e. when the stresses reach concrete strength), which would normally be widened under subsequent loading and encouraging fast penetration of corrosive substances, or (ii) Accumulate, reducing tensile-carrying capacity, thereby potentially invalidating the effectiveness of currently-adopted crack-control measures. Despite extensive research effort invested over recent decades since its first recognition, the risk of early-age cracking seems to be on the increase. That is possibly due to: (i) Our inadequate understanding of cracking mechanisms and its major influencing factors and (ii) Partly the constant evolution of concrete mixtures and construction practices over time. Modern concretes with higher early strength and lower water-binder ratio appear to increase its susceptibility to this form of cracking. This trend is further accelerated by growing adoption of higher-strength reinforcement that causes wider cracks. This research presents a distinctive concept to examine the underlying mechanisms of early-age cracking. Major objectives include: (i) Bridging current gaps in available knowledge of various concrete properties, and (ii) Either introducing new analytical models or suggesting further modifications in existing ones, to give better design-control method in practice.

Adopted methodology Through using a unique combination of novel tests at UQ, this research aims to propose and verify a distinctive concept of crack assessment model for young concrete. Fundamentally, the concept can be expressed in an analytical form as follows: = T + sh → [t] (Eq.1)

T = R K E T = R K E E/C (Tz(t) - T) (Eq.2)

Where: – Total stress induced in restrained concrete;

T – Absolute thermal stress induced in restrained

concrete;

sh – Stress caused by different types of shrinkage;

E/C – Coefficient of thermal expansion or contraction;

Tz(t) – Time-dependent Zero-stress temperature;

T – Real-time concrete temperature;

[t], E, K – Tensile strength, Young’s modulus and

creep factor;

R – Degree of restraint.

What differentiate the concept from previous ones include: (i) The assessment of thermal cracking risk along with other driving forces to cracking (e.g. different types of shrinkage) as in Eq.1, (ii) The introduction of time-dependent Zero-stress temperature as a benchmark to reliably estimate thermal stress as in Eq.2, (iii) The consideration of coefficients of thermal expansion and contraction separately, (iv) The investigation of tensile creep under realistic situation (i.e. where continuous temperature variation, hence stress and strain, normally occurs at early age), and (v) The comprehensive study of concrete tensile- and fracture properties from mixing, as well as the effects of modern construction techniques on their evolutions over time.

Findings and application of results Experimentally, the program relies on two state-of-the-art systems to investigate early-age concrete, including: First, an improved direct tensile testing system with (i) Consistently greater reliability and (ii) Successful application of Digital Image Correlation (DIC) technique for non-contact capturing of full-field displacement of very early-age concrete for the first time (Figure 2); Second, a newly-built Temperature-Stress Testing Machine (TSTM, being the first TSTM in Australia and among the very few internationally) with (i) Significant improvements compared to its earlier versions, and (ii) Reliability and repeatability established (Figure 3).


Unique combination of these two novel systems allows the study of those key objectives mentioned above. Accomplished fundamental knowledge can be listed as follows:

First, from direct tensile testing, a comprehensive collection of concrete properties from very early age (i.e. 3 hours from mixing for concretes used in this study) was obtained. This consisted of tensile characteristics (i.e. strength, Young’s modulus, strain at peak stress), fracture properties (i.e. fracture energy and characteristic length), behaviors under cyclic loading and stress relaxation. Such knowledge is significant for an effective assessment- and control of early-age cracking. Also from direct tensile testing, an investigation over the roles of micro-fibers on both crack prevention and crack development control at very early age was conducted. Moreover, combined with reported concrete properties at later age from previous studies, their comprehensive evolutions since casting were established.

Second, a new concept of Zero-stress temperature (Tz) was introduced, followed by the investigation of its temporal development under various influencing factors, during the first seven days of age. The knowledge is critically important for a reliable assessment of thermal strain or stress due to restrained thermal deformations during such sensitive period. In addition, from TSTM, both coefficients of thermal expansion and thermal contraction of young concrete were investigated.

Third, from collected TSTM data, related properties that strongly affect the risk of premature cracking were also examined and reported, including: Autogenous shrinkage, tensile creep under varying stresses and Young’s modulus under sustained loading from very early age.

On the basis of reliable experimental data summarized above, further analytical studies were carried out, the major outcomes of which as outlined in the following:

First, from the evolutions of concrete properties and their inter-relationships, a model for estimating the development of tensile strength and Young's modulus has been proposed and reported, together with its demonstrated predictive capability (Figure 4);

Second, a unified approach to estimate fracture energy, tensile softening curve and their

temporal evolutions, has been presented. Its applicability has been successfully confirmed for two popular types of approximation model – bi-linear- and power curves;

Third, the basic concept of a revised creep model has been introduced. Considering a realistic situation of tensile creep under continuously varying stress from very early age, the revised model includes both effects of progressive stress variation and overall creep tendency over time;

Fourth, a revised crack model has been proposed to assess early-age cracking risk. Fundamental bases of the model include: (i) Zero-stress temperature as a time-dependent benchmark to determine thermal stress (strain), (ii) Separate consideration of creeps on different motivations (i.e. thermal effect and shrinkages) and (iii) Integration of all important knowledge achieved in this program. The first verification has been conducted with promising outcomes, proving its appropriateness and encouraging further developments in the future.

References [1] Atkins, W. B. (1962). Connector plate, Google Patents.

Further Information Duy Nguyen ([email protected])

Fig 2 Direct tensile testing system from DIC cameras at UQ



Fig 3 Newly designed built Temperature-Stress Testing Machine at UQ

Fig 4 Study of tensile strength and its evolution, accompanied by a revised estimation model with proven reliability

Hencky bar-chain model for buckling and vibration analyses of beams and arches

07 Hong Zhang


Page 19


Project background, objectives and goals The aim of this project is to develop a Hencky bar-chain model (HBM) for the buckling and vibration analyses of Euler-Bernoulli beams and circular arches. The HBM comprises rigid beam or circular arc segments (of equal length a = L/n where L is the total length of beam or half arc length of circular arch and n the number of beam or arch segments) connected by frictionless hinges and elastic rotational springs (of stiffness C = EI/a where EI is the flexural rigidity of the beam or arch) which allows for flexibility of the model as shown in Error! Reference source not found.(a) and Error! Reference source not found.(b). The total mass M of the beam is concentrated at the joints with M/n for the internal joints and M/(2n) for the end joints. The total mass M of the arch is concentrated at the internal joints of magnitude equal to M/(2n) and M/(4n) for end joints. The HBM has been found to be equivalent to the finite difference model (FDM) as they possess the same mathematical form of governing equations. Therefore, HBM can be regarded as the physical model behind the first order central finite difference method. This paper presents the development of the HBM to handle beams with elastic intermediate and end restraints, the allowance for its selfweight, varying cross-section along its length, resting on Winkler foundation and circular arches.

L

EI, A, M=ρAL

C C C C

2

M

n

a=L/n

M

n

M

n

M

n

M

n 2

M

n

(a)

R

α

O

q

-α

φ R

n-n

n-1

0

-(n-1)1-1

α = nφ -α = -nφ

Hinge with rota tional spr ing stiffness

C = EI/a and lumped mass M/2n

O

EI, A, M=2ρAL

(b) Fig 1 (a) Euler-Bernoulli beam and its corresponding HBM (b) Circular arch and its corresponding HBM

Adopted methodology The methodologies of this work are summarized as follows:

Develop HBM for buckling and vibration analyses of beams with elastic intermediate and end restraints. Based on energy approach, the governing equation for HBM are derived and it is found to be equivalent to the governing equation for FDM. Later on, the boundary spring stiffness of HBM can be obtained based on the equivalence between HBM and FDM.

Develop HBM for buckling columns under selfweight and the exact solutions for HBM are obtained.

Develop HBM for buckling and vibration of beams resting on partial Winkler Foundation and of varying cross-section. HBM is further applied for optimal shape design of columns against buckling.

Develop HBM for buckling and vibration analyses of circular arches.

Findings and application of results The results and potential application of this work are summarized as:

The development of HBM assists in the understanding of physical meaning behind the first order central finite difference method. HBM has a wide application in modelling beam, circular arch and even plate structures.

HBM is not only a numerical method for solving continuum structural problems but is also a natural model for analyzing articulated (or discrete) structures such as Pelamis wave energy converter (see Figure 2).

The discrete property of HBM facilitates its simulation of nano-scale structures such as carbon nanotubes and graphene sheets as long as the segmental length of HBM is very short. Due to the phenomenological similarities between HBM and Eringen’s nonlocal model, HBM can be applied to calibrate the Eringen’s small length scale coefficient which is an important parameter for applying Eringen’s nonlocal model.


Fig 2 Pelamis wave energy converter

References None

Further Information Hong Zhang ([email protected]) Or Prof CM Wang ([email protected])



Load Transfer and Collapse Resistance of RC Flat Plates under Interior Column Removal Scenario

08 Huizhong Xue

Griffith University

Page 21


Project background, objectives and goals Reinforced concrete (RC) flat plate structures are vulnerable to punching shear failure at their slab-column connections, potentially leading to catastrophic progressive collapse (Hawkins and Mitchell, 1979). In practice, the slab-column connection above a removed interior column may be subjected to a concentrated downward force due to the absence of the supporting column and further being pushed due to different live load intensities on individual stories. This force, combined with the gravity load acting on the slab, may cause punching shear failure at the interior slab-column connection and further trigger failure propagation to the surrounding slab-column joints. This project presents the experimental tests performed on two identical

large scale 22-bay RC flat plate specimens under an interior column removal scenario (Figure 1). A 5kPa uniformly distributed load was applied first to the slab followed by an incremental concentrated force imposed on the joint above the removed interior column. The complete collapse resistant behaviour and the load redistribution pattern of the specimens were investigated and are reported herein.

Fig 1 Testing setup

Adopted methodology In order to investigate the structural behaviours of the RC flat plate structures subjected to the interior column loss, large scale substructure specimens were tested. The failure modes, crack development, load transfer pattern, and ultimate load carrying capacities were examined and analysed.

Findings and application of results Results show that more than 90% of the applied concentrated force is solely distributed to the four edge columns. Three load carrying mechanism phases, in form of flexure, tensile membrane, and a combination of one-way catenary and dowel actions

can be distinguished in resisting the applied concentrated load. The results revealed that the importance of the continuous bottom reinforcement passing through columns. The membrane action of the slab also provided the post failure load capacities which were critical for resisting progressive collapse.

References Hawkins, N. M., and Mitchell, D. (1979). "Progressive Collapse of Flat Plate Structures." ACI. J.

Further Information Huizhong Xue ([email protected])


Web crippling behaviour of aluminium lipped channel sections under two flange load cases

09 Husam Alsanat

Griffith University

Page 22


Project background, objectives and goals The application of aluminium alloy members in building construction has considerably increased in recent years due to their appealing advantages such as corrosion resistance, light weight and high strength-to-weight ratio. However, the elastic modulus of aluminium is only one third of that of steel, making aluminium being vulnerable to various buckling modes including web crippling. Web crippling is a form of localized failure which occurs at the support or at the point of transverse concentrated force applied on a short length of the beam. To date, only a limited amount of research study has been conducted to investigate the web crippling failure phenomenon in aluminium structural members, and no research has been carried out on the web crippling behaviour of cold-formed aluminium lipped channel sections. The aim of this project is to investigate the web crippling behaviour of aluminium lipped channel sections under End-Two-Flange (ETF) and Interior-Two-Flange (ITF) load cases (see Figure 1) and develop design rules to accurately predict the web crippling capacities.

(a) End-Two-Flange (ETF)

(b) Interior-Two-Flange (ITF)

Fig 1 ASI standard test method [1] for web crippling under two flange load cases

Adopted methodology An experimental study which includes 40 tests were carried out in this research to assess the web crippling behaviour and capacities of aluminium

lipped channel sections under two-flange load cases. The specimens were roll-formed in a well proven marine grade structural aluminium alloy 5052 H36. Five different section sizes (with two nominal thicknesses of 2.5 and 3 mm) were considered with four different bearing lengths (25, 50, 100 and 150 mm). The web height ranged from 100 to 250 mm while the flange widths ranged from 60.5 to 75 mm. The Top and bottom flanges of these channel sections were unfastened to the bearing plates (supports). The test set-up and failure modes are shown in Figure 2. The results obtained from this research were then compared with the nominal web crippling strengths predicted using the design rules provided in current Australian, American and European standards.

(a) ETF Load case

(b) ITF Load case

Fig 2 Test set-up and failure modes

Findings and application of results Two kinds of failure mechanisms were

observed during the tests which are (1) web crippling for specimens with 50,100 and 150 mm bearing plates and (2) combined flange crushing and web crippling for specimens with 25 mm bearing plates.

It is also found that all the specimens with 100 mm and 150 mm bearing plates under the ITF


load case did not reach their maximum bearing capacities because of their inadequate specimen lengths. Thus, the specimen lengths recommended by the AISI testing method [1] should be extended for aluminium lipped channel sections under the ITF load case.

The web crippling capacities of aluminium lipped channel sections from the tests were compared with the nominal strengths calculated using AS/NZS 1664.1 [2], Eurocode 3 [4], and AS/NZS 4600 [5]. It was found that the capacities predicted by the aforementioned standards are quite unconservative and unsafe (see Figure 3).

(a) ETF load case

(b) ITF load case

Fig 3 Comparison of current design rules with experimental results. In this study, suitable modifications were proposed for the available design equations based on the experimental results to accurately predict the web crippling capacities of aluminium lipped channel sections. As shown in Figure 4, the web crippling capacities predicted from the modified equations agreed well with the test results.

(a) ETF load case

(a) ITF load case

Fig 4 Test to predicted web crippling capacity ratios for the modified design rules, (a) ETF and (b) IFT Load cases.

References [1] American Iron and Steel Institute (AISI) (2008),

Standard test method for determining the web crippling strength of cold-formed steel beams, TS-9-05, DC, USA. [2] Standards Australia (SA) (1997), Aluminium structures - Part 1: Limit state design, AS/NZS 1664.1, Sydney, Australia. [3] European Committee for Standardization (CEN) (2006), Design of steel structures - Part 1.3: Cold-formed members and sheeting, EN 1993-1-3, Brussels, Belgium. [4] Standards Australia (SA) (2005), Cold-formed steel structures, AS/NZS 4600, Sydney, Australia.

Further Information Husam ALsanat ([email protected])

Or Dr S Gunalan ([email protected])



Parametric Study on Buckling of Pipe-in-pipe Systems under External Pressure

10 Mahmoud Alrsai

Griffith University

Page 24


Project background, objectives and goals Over the past two decades, the pipe-in-pipe (PIP) systems have become an essential part of the subsea field development and offshore pipeline applications due to their high thermal insulation performance. Pipe-in-pipe systems consist of a concentric inner pipe (also known as the product pipe) and the outer pipe (sometimes called carrier pipe). Typically, the annulus space between two pipes is filled with a non-structural insulation material such as polyurethane foam or water. In deep-water applications, where the hydrostatic pressure is high (water depths up to 3,000 m), the outer pipe must be designed to provide the mechanical protection from the subsea environment, while the design of the inner pipe is mainly based on high temperature and high pressure of transporting hydrocarbons inside the pipe. This high hydrostatic pressure may trigger a local collapse, such as propagation buckling or interaction between lateral/upheaval buckling modes and the propagation buckling mode in the carrier (outer) pipe. Structural integrity of the PIP system under external pressure is an issue of concern, because the collapse of the carrier pipe may result in collapse of the inner pipe.

Adopted methodology This study investigates the propagation buckling of subsea pipe-in-pipe (PIP) systems under hydrostatic pressure. Parametric studies are carried out to examine the effect of the parameters affecting the buckling collapse pressure mechanism of the PIP system by using the validated FE model. The 3D nonlinear (material and geometry) finite element (FE) model is validated by the experimental data. The previous studies have only covered propagation pressure of thick and moderately thick PIPs with diameter-to-thickness (Do/to) ratio smaller than 25. However, in this study the range of (Do/to) ratio has been extended to capture the effects of thin and moderately thin carrier pipes with Do/to of 30 and 40. The study shows that the propagation buckling of the PIP system is to a higher extent affected by the wall thickness ratio ti/to and the diameter ratio Di/Do and to a lower degree by the material yield ratio σYi/σYo. Based upon the extensive numerical results, two failure modes are identified as Mode A and B. Current results on propagation pressure of PIPs with various Di/Do ratios showed a nonlinearly decreasing trend which is associated with failure mode B and was not reported in the previous studies. The distinction point between failure modes A and B has been identified. Furthermore, this study suggests that existing equations do not provide accurate predictions of propagation pressure Pp2 of the thin and moderately thin PIPs. A more accurate empirical

formula for the propagation pressure Pps of the PIPs with solid inserts and more reasonable empirical formulae for propagation pressure Pp2 of the thin and moderately thin PIP systems are proposed. Additionally, a separate empirical formula has been proposed for a thick and moderately thick PIP systems.

Fig 2 Specimen with single nails 1) Understanding the mechanisms causing backout

was investigated through the moisture cycling of single nails in timber while monitoring the samples continuously for 40 days. The samples were monitored using two cameras, thereby allowing for a digital image correlation (DIC) to be made. The average mass of the samples, the applied temperature and humidity, and the surface strain recorded by the DIC are known.

2) From the single tooth investigation, two designs,

one mechanical based and one adhesive based,

Fig 1 R Finite element results showing pressure against nor-malized ovality and corresponding deformed shapes of PIP system exhibiting failure Mode A.

0

500

1000

1500

2000

2500

0 0.1 0.2 0.3 0.4 0.5

Pressure

(kPa)

ΔD/D

Do/to=40, Di/ti=30, Di/Do=0.45

to=2.0, ti=1.2, ti/to=0.6

IIIIII

IV V


Fig 1 R Finite element results showing pressure against nor-malized ovality and corresponding deformed shapes of PIP system exhibiting failure Mode B.

Findings and application of results The parametric study carried out in previous section ascertains the dependency of the propagation pressure of PIP system on ti/to, Di/Do and σYi/σYo

parameters. However current FE results prove that the failure modes of PIPs with large Do/to ratios are not essentially similar to mode A. Since the previous studies are based on mode A are incapable of predicting proper estimates of propagation pressure of PIPs that fail in mode B, it seems rational to propose separate expressions for each failure mode. Based on the results of the previous studies, the power expressions presented in Eqs 1 and 2 are

suggested for propagation pressure ratios of PIPs with collapse mode A and B respectively:

0.2 0.4 2.42

1 1.047p yi i i

p yo o o

P D t

P D t

(1)

0.2 0.8 2.42

1 0.596p yi i i

p yo o o

P D t

P D t

(2)

The expressions (Eqs. 1 and 2) can be used to predict the propagation pressure of PIP systems with thin and moderately thin carrier pipes. In order to come up with an expression to predict the propagation pressure of PIPs with thick and moderately thick carrier pipes, a total of 254 data points were collected from the raw data reported in [3,4], and the current FE results for PIPs with Do/to = 26.67. Using the Levenberg-Marquardt algorithm of non-linear least squares the following expression was derived for the propagation pressure, Pp2, of PIPs with Do/to < 27.

0.4 0.13 1.82

1 0.803p yi i i

p yo o o

P D t

P D t

(3)

References [1] Alrsai, M. & Karampour, H. 2016. Propagation Buckling of Pipe-in-Pipe Systems, an Experimental Study. In The Twelfth ISOPE Pacific/Asia Offshore Mechanics Symposi-um. International Society of Offshore and Polar Engineers. [2] H. Karampour, F. Albermani, Experimental and numerical investigations of buckle interaction in subsea pipelines, Engineering Structures. 66 (2014) 81-88. [3] S. Kyriakides, T. J. Vogler, Buckle propagation in pipe-in-pipe systems.: Part II. Analysis, International Journal of Solids and Structures. 39.2 (2002): 367-392. [4] Gong, G. Li, Buckle propagation of pipe-in-pipe systems under external pressure, Engineering Structures. 84 (2015) 207-222. [5] H. Karampour, M. Alrsai, F. Albermani, H. Guan, D. Jeng, Propagation Buckling in Subsea Pipe-in-Pipe Systems, Journal of Engineering Mechanics. 143 (2017) 04017113.

Further Information Mahmoud Alrsai ([email protected])

0

1000

2000

3000

4000

0 0.1 0.2 0.3 0.4 0.5

Pressure

(kPa)

ΔD/D

Do/to=30, Di/ti=15, Di/Do=0.40to=2.0, ti=1.6, ti/to=0.80

III

III IVV


Design of fire safe bamboo structures

11 Mateo Gutierrez Gonzalez


Page 26


Project background, objectives and goals The use of load-bearing bamboo structures has mostly been limited to low-rise structures. In recent years, laminated bamboo products have emerged with the potential of turning bamboo into a mainstream construction material. The potential of laminated bamboo has been unlocked by taking advantage of bamboo’s remarkable load-bearing performance and overcoming key challenges such as geometrical irregularity, the limited size of cross-sections, connection details, and the dispersion of mechanical properties [1]. Load-bearing structures made of round bamboo have traditionally been used in a wide range of applications; e.g. light bamboo frames with bamboo bracings, large roofs based on bi- and tri- dimensional trusses, and shear walls with bamboo skeletons are common structural systems of conventional bamboo construction; and mid- and high-rise construction [2]. The performance of load-bearing bamboo structures used in applications where fire safety considerations must be addressed before this can be used with the confidence we used other more traditional building construction materials. Structural integrity is key to assure appropriate evacuation of occupants and safe intervention of the fire brigade. Understanding the potential for fire-induced failure during or after fire must be understood. This project aims at investigating the fire performance of load-bearing bamboo structures through the analysis of exemplar bamboo systems loaded under a range of fire

scenarios.

Adopted methodology Initially, a set of experimental studies will investigate the reduction of mechanical properties of bamboo at elevated temperatures. Round and laminated bamboo will be experimentally investigated in the direction parallel to the fibre. Mechanical tests will be conducted in samples at steady-state conditions where the reduction in the compressive, tensile strength, or elastic modulus will be investigated (refer to Figure 1). Experimental outcomes to date are shown in Figure 2. Mid and large-scale fire tests and numerical modelling studies will allow for an understanding of full element behaviour on prototype bamboo systems: e.g. bamboo bahareque walls, laminated bamboo trusses. Outcomes from these studies will set the basis for developing fire safety design methods for structural systems incorporating bamboo; and setting the grounds for understanding the fire performance of bamboo structures.

Fig 1 Test set-up for compressive and tensile strength in round bamboo at elevated temperatures.

Findings and application of results Results from these experimental studies have shown that round and laminated bamboo looses about 50% of its compressive strength at about 70°C. At elevated temperatures, a shift in the failure mechanism is observed, and local buckling governs the failure of test samples. Regarding the tensile strength of bamboo, the material evidences a different behaviour to at under compression; since the drop in strength is lesser; approximately 10% at 70 °C, Moreover, bamboo seems to lose almost all capacity at temperatures around 200 °C. At elevated temperatures, the modulus of elasticity of bamboo experiences a reduction. Reduction in the MOE of load-bearing materials can severely influence the fire performance of structural systems (refer to figure 3).

References [1] Sharma, B., et al., Engineered bamboo for structural applications. Construction and Building Materials, 2015. 81: p. 66-73. [2] Correal, J.F., 14 - Bamboo design and construction, in Nonconventional and Vernacular Construction Materials., K. Harries and B. Sharma, Editors. 2016, Elsevier Ltd. p. 393-431.

Further Information Mateo Gutierrez Gonzalez ([email protected])



Fig 2 Compressive and tensile strength reduction in round bamboo at elevated temperatures.

Fig 3 Elastic modulus reduction in laminated bamboo at elevated temperatures

0.00

0.20

0.40

0.60

0.80

1.00

1.20

0 50 100 150 200 250

Norm

ali

sed

Str

eng

th (σ

Tem

p/σ

am

b)

Temperature (°C)

Tensile Strength

Compressive Strength

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 40 80 120 160 200

Norm

ali

sed E

last

ic M

odu

lus

Temperature (°C)

Post-Punching Mechanism of Slab-Column Joints Subjected to Upward and Downward Punching Shear Actions

12 Mengzhu Diao

Griffith University

Page 28


Project background, objectives and goals In flat plate structures, the slab-column joint is prone to punching shear failure, which would trigger progressive collapse of the entire structural system (Hawkins and Mitchell 1979). Progressive collapse is a mechanical behaviour under large deformations. However, most conventional studies on RC flat-slab structures have been mainly focused on the punching shear behaviour of slab-column joints under small deformations and various construction detailing techniques to enhance the punching shear capacities (Ruiz et al. 2010, Carvalho et al. 2011). Specifically, existing research studies have focused on the behaviour of the joints before and after upward punching shear (UPS) failure which commonly occur when the slabs are over-loaded by downward gravity. On the other hand, downward punching shear (DPS) failure likely induced by the uplifting loads acting on the slabs, such as blast, is rarely being concerned (as shown in Fig.1). This project aims to gain in-depth understanding of the collapse-resistant behaviour of RC flat plate structures exhibiting two different failure modes through a series of static collapse tests conducted on four slab-column joint specimens with missing columns.

Fig 1 Failure modes of slab-column joints in progressive collapse

Adopted methodology The effects of different punching directions (UPS and DPS) as well as embedded beams on the post-punching performance of the joints were studied by analysing the developments of the material damage, the overall deformation and the collapse resistance of the specimens.

Findings and application of results The test results illustrate that the post-punching bearing and deformation capacities are governed by the through column longitudinal reinforcement.

The post-punching mechanisms of the specimens with the embedded beams were identical despite of the opposite punching shear actions. In addition, the embedded beams increased the resistance and the deformation capacity of the specimens under both the flexural and suspension mechanisms.

References Hawkins N M, Mitchell D. Progressive Collapse of Flat Plate Structures [J]. ACI Structural Journal, 1979, 76(7): 775-808. Ruiz M F, Muttoni A, Kunz J. Strengthening of Flat Slabs Against Punching Shear Using Post-Installed Shear Reinforcement [J]. ACI Structural Journal, 2010, 107(4): 434-442. Carvalho A L, Melo G S, Gomes R B, Regan P E. Punching Shear in Post-Tensioned Flat Slabs with Stud Rail Shear Reinforcement [J]. ACI Structural Journal, 2011, 108(5): 523-531.

Further Information Mengzhu Diao ([email protected])

Collapse propagating

Downward punching shear (DPS)

Upward punching shear (UPS)

Floor load Floor load

Collapse propagating

Upward punching shear (UPS)

Floor load Floor load

Uplifting load Uplifting load


Fire Performance and Design of CFRP Strengthened and Insulated Cold-Formed Steel Tubular Columns

13 M Imran

Queensland University of Technology

Page 29


Project background, objectives and goals Carbon fibre reinforced polymers (CFRP) are rapidly gaining acceptance as potential materials for repairing and strengthening cold-formed steel tubular columns that may have deteriorated due to structural aging, corrosion, increased loads and disaster exposures. However, CFRP’s sensitivity to high temperature exposures compared to other conventional retrofitting materials and limited knowledge on CFRP’s thermal and mechanical behaviour in fire have raised concerns relating to their fire performance. These concerns have hindered designers from using CFRP retrofitted steel columns for members that require fire resistance rating. Therefore this research is aimed at enhancing the knowledge and understanding of the fire performance of CFRP retrofitted cold-formed steel tubular columns. It has proposed the use of an external insulation layer to protect CFRP retrofitted steel tubular columns and to increase the fire performance level. For this purpose, both experimental and numerical investigations were undertaken at the Queensland University of Technology. Experimental investigations consisted of: elevated temperature thermal and mechanical property investigations of cold-formed steel, CFRP composites, adhesives and insulation materials; elevated temperature steady and standard fire tests of CFRP retrofitted and insulated short and long steel tubular columns. 3D thermal and structural finite element (FE) models were developed using ABAQUS finite element analysis software and validated using the experimental results of the current study. Numerical and experimental results will be used to develop suitable design rules and CFRP and Insulation systems for maximum fire performance of cold-

formed steel tubular columns will be proposed.

Adopted methodology The methodology of the research are summarised as follows.

Experimental investigation of CFRP strengthened cold-formed steel tubular columns under steady state fire conditions

Experimental investigation of CFRP strengthened and externally insulated cold-formed steel tubular under standard fire conditions

Development of elevated temperature mechanical property reduction factors for cold-

formed steel sections through a detailed experimental study

Determination of elevated temperature thermal properties of carbon fibres, adhesives, CFRP composites and commonly used spray applied insulation materials

Development of Finite Element Models (FEM) of CFRP strengthened steel tubular columns and validation of those based on experimental results

Based on detailed parametric study, propose suitable equations to determine the axial capacity of CFRP strengthened steel tubular columns

Develop suitable CFRP and Insulation systems to maximise the fire performance of cold-formed steel tubular columns, and associated fire design rules to determine their fire resistance ratings

Findings and application of results The results and potential outcomes of the research are summarized as follows.

CFRP strengthened steel columns exhibited exceptional performance by providing enhancement up to 2.6 times than the bare steel column at ambient temperature

However, sever degradation in axial capacity was observed when the CFRP strengthened steel columns were exposed to temperatures beyond the glass transition temperature of the adhesive (66°C)

The fire performance of CFRP strengthened steel columns were improved by having an external insulation system, where more than 60 mins of fire ratings were achieved.

Knowledge gap of elevated temperature thermal/mechanical properties of steel, carbon fibres, adhesives, CFRP and insulation materials were addressed and suitable equations were proposed

Design rules were proposed to determine the axial capacity of CFRP strengthened and insulated steel columns at ambient and fire conditions

Suitable CFRP and insulation configurations will be proposed for optimum fire performance

References: None

Further Information Mohamed Imran ([email protected])


Fatigue design of thin steel roof batten to rafter connections under cyclic wind uplift loading

14 Myuran Kathekeyan


Page 30


Project background, objectives and goals Thin steel roof claddings and battens are widely used in low rise buildings all around the world. However, they are vulnerable to premature connection failures when subjected to severe wind uplift actions such as those induced by cyclones and storms. Current design method based on Low-High-Low (LHL) cyclic testing (Fig 1) method (Australian Building Codes Board 2015) exclusively depends on full scale prototype roof tests developed mainly for steel roof cladding to batten connections. Therefore, this study investigates the suitability of the current test method for batten to rafter/truss connection (Fig 2) design and proposes alternative simple design methods using a set of simple equations developed through a series of full and small scale static and cyclic pull-through tests of roof battens. Since an acceptable small scale connection test method is not available for fatigue pull-through failures of roof battens, a series of constant amplitude cyclic tests was conducted first to determine the suitable small scale test method. Using the small scale test method, the suitability of the current LHL test method was then investigated for roof battens made of different thickness, grade and screw head diameter. Test results revealed that sequence effects and loading/strain rate sensitivity of steel have to be considered for accurate design of roof battens to rafter/truss connection. Therefore, a series of Low-High (LH), High-Low (HL) and LHL tests and a series of pull-through and tensile coupon tests at various loading rates were conducted to investigate the sequence effect and loading rate sensitivity, respectively. Based on the test results, a suitable recommendation in relation to the current LHL cyclic test load sequence and loading frequency was made. Finally, a single-term exponential model was developed using the constant amplitude cyclic tests to determine the pull-through capacity of roof battens under constant amplitude cyclic loadings. For various amplitude cyclic loadings, linear and non-linear Miner’s damage accumulation models were verified using LH, HL and LHL test results. The single-term exponential model and the proposed Miner’s linear and non-linear rules enable safe roof batten design without the need for full scale LHL cyclic tests of prototype roof assemblies.

Fig 1 LHL cyclic test sequences Fig 2 Typical roof connections

Adopted methodology The methodology of this work is summarized as follows:

Identification of primary and secondary parameters that influence the fatigue pull-through behaviour of roof battens via detailed literature review.

Development of small scale connection test method for fatigue pull-through failure studies of roof battens, considering the secondary influential parameters (effect of bending and

Batten to rafter

connection

Cladding to batten

connection (Crest-fixed)

Roof batten

Roof cladding


support reactions), through a series of constant amplitude cyclic tests based on three different small scale test methods (short, cantilever and two-span batten test methods).

Verification of the suitability of current LHL test method for roof batten to rafter connection by considering the sequence and loading rate sensitivity effects, using the determined suitable small-scale test method.

Development of a simple design equation (based on the principles of fatigue design by means of S-N curves) by considering the primary influential parameters (batten thickness, grade and screw head diameter) and using the constant amplitude cyclic tests to determine the fatigue pull-through capacity of roof battens under constant amplitude cyclic loading.

Verification of the suitability of linear and non-linear Miner’s damage accumulation models to determine the fatigue life and damage corresponding to various amplitude cyclic loading using a series of LH, HL and LHL cyclic tests.

Development of a suitable hybrid design equation to determine both static and fatigue pull-through strengths of roof battens subject to constant and various amplitude cyclic loadings.

Development of accurate finite element models (Abaqus), by simulating cyclic material properties using non-linear kinematic and isotropic hardening model (combined hardening), to simulate the fatigue crack initiation and propagation (XFEM) at the batten to rafter connections to understand the fatigue behavior of battens, and consequently propose guidelines to evaluate the fatigue performance of thin steel roof battens.

Findings and application of results

Current fatigue design method based on LHL cyclic

tests involves multi-span roof assemblies made of

roof cladding and its immediate supporting

members such as roof batten and rafter and their

connections. Besides, the test should be repeated

multiple times, considering the variability of

structural components. As a result, these tests

become complex, expensive and time consuming.

Moreover, findings of this study show that the

sequence and strain rate sensitivity effects

negatively impact the LHL cyclic test. Therefore, the

development of design equations (Eqs 1~4) to

determine fatigue pull-through strength of roof

battens subjected to both constant (Eq 3) and

various amplitude (Eq 1) cyclic loading helps to

overcome these issues and reduce the national

expenditure on disaster mitigation by ensuring the

safety of building roofs under severe wind loading

such as those induced by cyclones.

The results and potential application of this work are

summarized as follows;

Test results yielded a suitable small scale

fatigue test method and showed that the

present state of knowledge based on static

pull-through studies could lead to the use of a

wrong test method in fatigue pull-through

studies.

This study showed that both static and fatigue

pull-through capacities increase with

increasing loading rate. Based on pull-through

and coupon test results, a suitable

recommendation in relation to the current LHL

cyclic test loading frequency was made.

Similar to loading/strain rate sensitivity,

sequence effects of steel also influence the

cyclic performance of roof battens. This

influence on LHL cyclic test leads to

unconservative designs, and therefore these

effects have to be considered for accurate

fatigue pull-through design of roof battens.

A single-term exponential model (Eq 3) was

developed using S-N curves to determine the

fatigue pull-through capacity reduction factors

and was unified with the current static pull-

through capacity equations (Eq 4) to

determine both static and fatigue pull-through

capacities of steel roof battens. The proposed

unified equations facilitate effective design of

roof battens subjected to constant amplitude

cyclic wind loading.

Considering non-linear Miner’s damage

accumulation theories, an equation (Eq 1) was

developed to determine the fatigue

life/capacities of roof battens subjected to

various amplitude cyclic loads. This equation

along with the unified pull-through equation

enable safe, quick and convenient roof batten

design without any prototype tests of roof

assemblies such as LHL cyclic tests.


1......

13

21

1

1

3

3

2

2

1

1

m

m

m

m

N

n

N

n

N

n

N

n

N

n

m

(Eq 1)

1i

ii

N

N

(Eq 2)

c

b

aFFnN ovi

i

(Eq 3)

Fov = 3.07 t1.4 d0.6 fu for G300 battens = 8.68 t2 fu for G500~550 battens

(Eq 4)

where, i (1 ≤ i ≤ m) – particular stress amplitude

loading sequence, m - total number of various stress

amplitude loading, ni - number of cycles applied in

the ith stress loading, and Ni - total number of cycles

to failure in the ith stress loading. ɤ – constant equal

to -2.35, Fov - static pull-through capacity

(Sivapathasundaram and Mahendran, 2015), Fi -

maximum cyclic load in the ith stress loading (fatigue

pull-through load for which Ni is required to be

calculated), a, b and c are material constants given

in Myuran and Mahendran (2017), t is the batten

thickness, d is the screw head diameter and fu is the

ultimate tensile strength of the steel

References Australian Building Codes Board (2015), National Construction Code, Volume two: Class 1 and class 10 buildings, Australian Building Codes Board, Canberra, Australia. Sivapathasundaram, M., Mahendran, M. (2017), Numerical studies and design of thin steel roof battens subject to pull-through failures, Engineering Structures, 146, pp. 54-74. Myuran, K., Mahendran, M. (2017), Unified static-fatigue pull-through capacity equations for cold-formed steel roof battens, Journal of constructional steel research, 139, pp. 135-48.

Further Information Myuran Kathekeyan ([email protected])


Experimental and theoretical studies on three-side restrained reinforced concrete walls

15 Nhat Minh Ho

Griffith University

Page 33


Project background, objectives and goals Reinforced concrete (RC) walls are designed to withstand gravitational and lateral loadings. Walls subjected to in-plane vertical loads could become accidentally eccentric due to a range of loading conditions such as corbel elements applied to the wall face, imperfections in construction, uneven loading being experienced on top of the wall and temporary loading during operation and/or maintenance (Lima et al., 2014), which can result in a pronounced out-of-plane curvature. Axially loaded RC walls can be supported at the bottom end by a floor system and at the top end by a roof structure or another floor, as shown in Fig 1(a). However, RC walls are often combined to form I-, C-, T- and L-shapes to make efficient use of building areas in multi-storey buildings, as shown in Figs 1(b-c). With these configurations, walls may also be laterally supported on either or both sides by interconnecting walls. As a result, these lateral restraints transform the one-way action (OW) behaviour of axially loaded walls to two-way action (TW) behaviour. In many circumstances, due to architectural requirements and/or functional modifications of the structures, provision of openings for doors and windows or paths for ventilation systems is unavoidable, yet openings have clear negative effects through the introduction of disturbed regions that significantly decrease the elements’ ultimate load capacity, stiffness and energy dissipation (Popescu et al., 2017). Axially loaded walls can be designed using simplified design methods given in codes such as the Australian Concrete Standard (AS3600-09), the Eurocode 2 (EC2-04) and the American Concrete Institute Code (ACI318-14). While ACI318-14 provides a wall design equation intended for load bearing walls supported at top and bottom only, in AS3600-09 and EC2-04, the effects of side restraints are included. Nevertheless, Popescu et al. (2015) and Ho et al. (2017a) demonstrated that these simplified code design methods are considered to be restrictive and conservative. Many researchers have investigated the behaviour of RC walls either in OW or TW restrained on all four sides (TW4S) with and without openings. Little research has yet been published on the behaviour of walls supported on three sides (TW3S). Further, a number of contradictions were observed in the experimental results in that research (Ho and Doh, 2017). As such, the overall aim of this research is to enhance the fundamental understanding and to provide insight into the behaviour of TW3S walls. The primary objectives of this research included, but were not limited to: (1) Assess the current research level carried out worldwide on TW3S walls with and without openings; (2) Investigate thoroughly the structural behaviour of

TW3S walls, as influenced by geometric and material nonlinearities, boundary conditions and opening configurations; and (3) Derive more realistic design models for estimating the ultimate bearing capacity of TW3S walls.

(a) OW (b) TW3S (c) TW4S

Fig 1 Walls with various support conditions (Ho et al, 2017b)

Adopted methodology The research was performed by following the conventional methodological approach in order to accomplish the research objectives. The research method included three distinct research phases:

Knowledge acquisition: A literature review of existing knowledge, consisting of practical design code methods and outcomes of relevant published research in the subject area, indicates that there has been limited research on the structural behaviour of axially loaded TW3S walls considering slenderness ratio, aspect ratio and opening configurations. Consequently, these variables were given significant focus in this research. Furthermore, research questions were formulated following the research gaps identified in existing knowledge.

Data collection: An experimental program was

conducted to obtain the necessary information and data. A total of eighteen one-third to one-half scale wall panels were cast and tested. The experimental outcomes include crack patterns, load-deflection profiles and failure loads. As it was not practical to conduct more experiments due to resource restraints, a finite element model (FEM) using ABAQUS software and an instability analysis, all validated by the test results, were then employed as cost-effective tools to generate a wider range of data.

Analysis: An in-depth evaluation was implemented to investigate patterns in the obtained data in order to provide information in


regards to the design and analysis of TW3S walls.

Findings and application of results The results and potential application of this work are summarised as:

The research on the structural behaviour of TW3S walls with and without openings is relatively unexplored, which was identified via an extensive literature review. A test program was undertaken to investigate this unexplored area. In conjunction with physical experimental work, comprehensive numerical investigations were then conducted for the purpose of reducing the number of labour intensive and very costly laboratory tests.

The code design formulae were found to be either inapplicable to TW3S walls with and without openings of high slenderness ratios with various aspect ratios, or inadequate in predicting failure load for such walls, where predictions yield very conservative or even zero capacity. These predictions are clearly not the case, as test results indicate that significant capacities can be achieved. Alternatively the codes allow for any wall to be designed using the column provisions. For instance, when designing a wall with openings engineering practitioners make the judgement to split the wall into segments of columns connected by cross beams at openings, which then requires the design of each individual segment (Fragomeni et al., 2012). Despite being reasonably acceptable, a minimum vertical reinforcement content of 1% is required once using the column method. Further, it would be more convenient if practitioners were provided with simplified equations or a straightforward procedure to evaluate the ultimate capacity of the walls. With the current advancement in construction materials and technologies, significant cost savings and the increase in the net leasable space of a building could be achievable through the design and use of thinner walls. Hence, it is becoming increasingly important to carry out a satisfactory and less conservative design of structural wall elements.

Due to the fact that there are limited available methods for predicting the ultimate loads of TW3S walls, the provision of such methods with broader applicability is a necessary requirement for engineering applications. Simplified design models, covering a wider range of practical application, are therefore going to be proposed in this research. These include a modification of the

AS3600-09 equation and a modification of the rigid-plastic approach, which would be calibrated by the outcomes of extensive experimental and numerical studies.

References ACI Committee 318, Building code requirements for structural concrete (ACI318-14) and commentary, American Concrete Institute, Farmington Hills, MI, USA 2014. AS3600-09, Concrete Structures, Standards Association of Australia, North Sydney, NSW, Australia 2009. C. Popescu, G. Sas, T. Blanksvӓrd, B. Tӓljsten, Eng. Struct. 2015, 89, 172. C. Popescu, G. Sas, T. Blanksvӓrd, B. Tӓljsten, J. Compos. Constr. 2017, DOI: 21(3): 04016106. EN 1992-1-1, Eurocode 2: design of concrete structures – Part 1 – 1: General rules and rules for buildings, Comité Européen De Normalisation, Brussels 2004. M.M. Lima, J.-H. Doh, D. Miller, Experimental study of RC walls with openings strengthened by CFRP, Proceedings of 23rd Australian Conference on the Mechanics of Structures and Materials, 2014. N.-M. Ho, J.-H. Doh, S. Fragomeni, Struct. Des. Tall Special Build. 2017a, DOI: 10.1002/tal.1353. N.-M. Ho, J.-H. Doh, T. Peters, Load bearing capacity of three-side restrained RC walls. Proceedings of 28th Biennial Nation Conference of the Concrete Institute of Australia, 2017b. N.-M. Ho, J.-H. Doh, Struct. Des. Tall Special Build. 2017, DOI: 10.1002/tal.1459. S. Fragomeni, J.-H. Doh, D.J. Lee, Adv. Struct. Eng. 2012, 15, 1345.

Further Information Nhat Minh Ho ([email protected])


Section moment capacities of Hollow Flange Steel Plate Girders

16 Nilakshi Perera


Page 35


Project background, objectives and goals Hollow flange steel plate girder (HFSPG) is a new hollow flange I-section made using cold-formed rectangular hollow sections (RHS) as flanges and a steel plate as web (see Fig 1). Due to the increased torsional rigidity, doubly symmetricity and unique geometry, it can provide enhanced flexural capacities and thus are effective flexural members in long span applications. The production of proposed HFSPGs is based on welding currently available RHS sections to a web plate, which allows the engineers to form girders by varying dimensions, thicknesses and grades to suit their design requirements. Although earlier researchers have been conducted on the flexural capacities of hollow flange sections, HFSPGs have not been investigated previously. Therefore, section moment capacity tests (Fig 2) were carried out to study the flexural performance and capacities of HFSPGs. The ratios of ultimate moment capacity per unit area of tested beams were compared with conventionally used hot-rolled I-sections with similar cross-sectional area, which proved the structural efficiency of HFSPGs over commonly used hot-rolled I-sections. Suitable nonlinear finite element models were also developed (Fig 3) to simulate the section moment capacity tests conducted on HFSPGs. The comparison of ultimate section moment capacities, moment versus deflection curves and failure modes proved the validity of the developed finite element models to study the flexural behavior of HFSPGs. Since the slenderness of the tested HFSPGs was limited to a limited inelastic region, a numerical parametric study was undertaken to extend this study of HFSPGs. The ultimate section moment capacities of HFSPGs from tested and finite element analyses were then compared with capacity predictions provided by the Australian, American and European design standards. This comparison showed that the available design guidelines predict the flexural capacities of HFSPGs over-conservatively, and the level of under-estimation of capacities varied depending on the section slenderness, thus suitable modifications were proposed for the design rules of HFSPGs.

Adopted methodology The methodologies of this work are summarized as follows:

Demonstrating the possibility of replacing conventionally used hot-rolled I-sections by highlighting the potential benefits of HFSPGs over typical WBs and UBs.

Review of earlier researches conducted on the flexural behavior of hollow flange section beams and develop suitable modifications for design codes AS 4100 (SA, 1998), AS/NZS 4600 (SA, 2005), Eurocode 3 Part 1.1 (2006), Eurocode 3 Part 1.3 (2005) and AISI S100-2012.

Experimental investigation of the section moment capacities of the proposed HFSPGs subjected to local buckling effects. However, only the HFSPGs with small cross-sections were tested experimentally depending on the space and loading capacities available in the laboratory.

Development of finite element models of HFSPGs and investigate their behavior under local buckling to predict their section moment capacities.

Validation of the developed finite element models using experimental results.

Conducting a comprehensive parametric study in order to study the section moment capacities of all the possible HFSPGs considering higher grades and various sizes.

Comparison of the available design guidelines in AS 4100 (SA, 1998), AS/NZS 4600 (SA, 2005), Eurocode 3 Part 1.1 (2006), Eurocode 3 Part 1.3 (2005) and AISI S100-2012 to determine the design rules that predict the behavior and strengths of the proposed HFSPGs more accurately.

Introduction of the new design rules for the prediction of section moment capacities of HFSPGs if needed.

Findings and application of results Findings of this study show that the proposed HFSPGs are capable of achieving higher section moment capacities when compared with the available UBs in terms of capacity per unit area. Also, when compared to the hollow flange sections introduced in literature, the new HFSPGs, do not have the issues regarding the failure at the web-flange connections due to the welding connection used. Therefore, HFSPGs are recommended for use as flexural members in long span applications. However, further research study is being carried out at the Queensland University of Technology to investigate the member moment capacities of HFSPGs subject to lateral torsional and lateral distortional buckling effects. At the end of this study, it will be able to introduce flexural members with higher section and member moment capacities which can replace the conventionally used UBs and WBs. The results and potential application of this work

are summarized as:


A brief comparison between the section moment capacities of HFSPGs and commonly used UB sections proved that HFSPGs have a significant potential to replace the industrial UBs and WBs.

Section moment capacity tests were conducted, which include compact, non-compact and slender sections. The ultimate section moment capacities obtained from the tests were compared with the capacities predicted by the relevant design equations in the current steel design standards, which showed that all of them gave conservative predictions in general and the level of inaccuracy varied depending on the section type.

The finite element models were developed considering the material nonlinearities, boundary conditions and initial imperfections. These models were validated and showed good agreement with the corresponding experimental results. After comparing the results with the DSM (direct strength method) curve, it showed that the available DSM also predicts the capacities of HFSPGs conservatively.

A detailed parametric study was conducted to investigate the flexural behavior of HFSPGs subject to local buckling and yielding effects over a wider slenderness range. A new DSM equation was proposed with suitable capacity reduction factors for compact, non-compact and slender sections.

Comparing the new DSM equations with available DSM equations in AS/NZS 4600 and AISI S100-2012 showed that the new equations gave more accurate results. However, it was concluded that for slender HFSPGs, new DSM, AS/NZS 4600 (EWM), Eurocode 3 Part 1.1 (ECS, 2005) and Eurocode 3 Part 1.3 (ECS, 2006) provide accurate predictions, whereas, for non-slender HFSPGs, new DSM, AS 4100 and Eurocode 3 Part 1.3 can be used. Therefore, the new DSM and Eurocode 3 Part 1.3 are considered to provide the best capacity predictions for HFSPGs with any slenderness. Among them the most convenient capacity prediction method is given by the new DSM as Eurocode 3 Part 1.3 requires complex calculations.

References Nilakshi Perera, & Mahen Mahendran, “Section moment capacity tests of hollow flange steel plate girders” Proceedings of the 8th International Conference on Steel and Aluminium Structures 2016. Hong Kong, China, 7-9 Dec. 2016.

Further Information: Nilakshi Perera ([email protected])

Fig 1 Hollow Flange Steel Plate Girders (HFSPGs) Fig 2 Four points loading test set-up Fig 3 Finite element model of HFSPG

RHS sections

Web Plate

Spreader

Beam

Support

box

Lateral

Restrain

ts

LVDRoller

support

Testing Beam

Steel

Roller

s


Biaxial bending behaviour of cold-formed steel storage rack uprights

17 Nima Talebian

Griffith University

Page 37


Project background, objectives and goals Rack-supported buildings, also referred to as “clad racks” (see Fig 1), are currently gaining popularity in the logistic industry. The storage rack, usually manufactured from cold-formed steel members, supports both the building enclosure and the stored goods. Due to combined actions of wind loading and stored pallets, uprights undergo a combination of biaxial bending and compression. In this research, the focus of attention is only on pure biaxial bending capacity of the uprights. Internationally, the design method for these types of members is formally available in the cold-formed steel structures specifications such as the North American AISI-S10 (2016), Australian and New Zealand standard AS/NZS 4600:2005 and Eurocode 3 (2006). In these specifications, a linear interaction equation is used to account for members subject to biaxial bending and may be inaccurate. In order to produce safe and economical design guidelines, the actual interactive relationship between bending about the major and minor axes, for local and distortional buckling, is experimentally investigated in this project for two types of commercialised storage rack uprights. To determine the influence of perforations on biaxial bending capacity, biaxial bending responses of regularly perforated and non-perforated uprights are tested and discussed.

Fig 1 Clad rack in construction

Adopted methodology Two different types of rack uprights with different cross-sections, referred herein as “Type A” and “Type B” are investigated. Both uprights are commercially available but Type A has been specifically rolled-formed for the purpose of this

research to a thinner thickness than that of the commercialised uprights to ensure that Type A upright has local and distortional nominal capacities according to the Direct Strength Method (DSM) in AS/NZS 4600: 2005 which are lower than the yield moment. On the contrary, Type B has a compact section with the nominal moment capacities equal to the yield moment. To investigate the effect of perforations on the member capacity and biaxial bending interaction, Type A uprights were tested with and without regular perforations along their length whereas all tested Type B uprights were perforated. The lengths of the tested uprights (per upright type and buckling mode) were solely determined from buckling analyses of the non-perforated uprights bent about the x-axis of symmetry via Abaqus. A four-point bending test set-up was used to test the uprights under pure biaxial bending. Both ends of the uprights were bolted to solid pinned connections which were connected to two short segments of steel Rectangular Hollow Sections (RHS) to form a beam, as shown in Fig 2. In order to bend the upright about its two principal cross-sectional axes, the upright was rotated about its centroidal axis. The pinned connections were manufactured using heavy duty roller bearings in order to resist the applied bending moment, while allowing the ends of the uprights to freely rotate about the axis perpendicular to the applied moment. This testing arrangement creates a statically determinate system. In order to obtain a sufficient number of points to apprehend the biaxial bending interaction curve, seven different bending configurations per upright type were tested. Three Linear Variable Displacement Transducers (LVDT) were used to measure the cross-sectional deformation at mid-length of each specimen. As the frame moved with the upright, only the actual cross-sectional deformation due to local and distortional buckling was recorded.


Fig 2 Experimental four-point bending test setup – Schematic view

Findings and application of results Results show that a nonlinear interactive relationship governs the biaxial bending of the studied uprights. Also, the linear interaction equation in design specifications is conservative and underestimates the biaxial bending capacity by up to 44% and 68% for local and distortional buckling, respectively. Three different approaches are investigated in this project to compare the test results with DSM results, namely; (i) By using the DSM equations given in the AS/NZS 4600:2005, with the nominal member capacity equal to the yield moment for compact cross-sections, (ii) Through exploiting the inelastic reserve capacity for compact cross-sections, as permitted in the new AISI-S100 (2016) and (iii) By adopting an extended inelastic reserve strength. Comparison between the experimental results and the DSM equations shows better predictions but still underestimates the biaxial bending capacity by up to 27% and 36% for local and distortional buckling, respectively. A FE model has been calibrated against the experimental test results performed in this research to be used in parametric studies, using a range of existing commercialised storage uprights, to provide sufficient data to fully apprehend the actual biaxial bending interaction for cold-formed steel storage rack uprights in local, distortional and global buckling. Through obtaining sufficient data, the appropriate form of the DSM to predict the biaxial

bending capacity of cold-formed steel storage rack uprights can be determined.

References AISI-S100 (2016). "North American Specification for the design of cold-formed steel structural members." American Iron and Steel Institute. AS/NZS (2005). Cold-formed steel structures, Sydney: Australia: Standards Australia. EN 1993-1-3 (2006). "Eurocode 3. Design of steel structures. General rules. Supplementary rules for cold-formed members and sheeting." European committee for standardisation, Brussels, Belgium. Pham, C. H., and Hancock, G. J. (2013). "Experimental investigation and direct strength design of high-strength, complex C-sections in pure bending." Journal of Structural Engineering, 139(11), 1842-1852.

Further Information Nima Talebian ([email protected])


Structural Performance of Aluminium Façade Mullions under Wind Actions

18 Thananjayan Sivaprakasam


Page 39


Project background, objectives and goals

The aim of the research is to investigate the structural performance of aluminium mullion couples made of asymmetric male and female mullion sections used in unitized curtain walls of high-rise buildings subject to both positive and negative wind actions in order to develop a suitable method to determine their structural capacity. In order to achieve this aim, full-scale wind pressure tests were conducted on facade panels that are made of a commercially used mullion couple section. The structural behaviour and the ultimate failure capacity of the mullion couple were obtained from the full-scale tests in order to make a good understanding of the mullion couple system. However, a limited number of full-scale tests were conducted due to cost and time factors, thus a comprehensive understanding of a wide range of mullion sections and the different facade systems cannot be gained. Therefore, finite element analysis (FEA) approach was also employed in this study following the validation of the finite element models (FEMs) using the results from conducted full-scale test results. These mullion sections are of complex open profiles, and their shear centre is located outside the sections. Therefore, the wind loads that are transferred from glass panes to the mullions act eccentrically to their shear centre. This induces torsional forces in addition to bending in the mullions. However, the currently used design standards and methods do not account for these effects, and the currently made assumptions could result in conservative or unconservative designs. Therefore, the ADM (AA, 2015) based design approach was also investigated in this study in order to assess its applicability for the mullion design.

Adopted methodology The methodology of this research is summarized as follows:

Identify the strength and weakness of the available past studies on the structural performance of the mullion couples, and justify the need for a detailed study through literature review.

Conduct full-scale tests of curtain walls made of a selected mullion couple to develop reliable structural performance data of mullion couples under both positive and negative wind actions.

Develop finite element models using ABAQUS software to predict the structural behaviour of

mullion couples and validate them using the full-scale test results.

Conduct an extensive finite element analysis (FEA) based study on different mullion couple sections.

Assess the currently used design approaches and assumptions in order to provide safe and economical solutions for façade systems.

Findings and application of results The glazed facade system claims a significant portion (about 20%) of the total cost in a building project (Mudie and Rawlinson, 2010). There is a possibility of reducing the use of materials and thus associated costs if the structural behaviour of the mullion couples is well understood (Hui et al., 2015). The currently used design standards and methods have many drawbacks in relation to the design of these complex mullion sections. Therefore, the results from the experimental and FEA based study will be advantageous in order to develop a safe and economical design method for the mullion couple systems. The potential outcomes obtained based on the conducted full scale tests and the associated FEAs are summarized next:

During the negative wind action, the male and female mullions rotate to lean on each other at their unrestrained compression flange (Fig. 1). However, this leaning action did not help the mullion couple to achieve a significant capacity improvement as expected.

Although the leaning action of the mullions does not support the male and female mullions to act as a single section, a significant capacity increment is possible compared to the capacity predictions based on ADM (AA, 2015) design approach.

The capacity of the mullion couple under positive wind action is higher than that under negative wind action. It is because of the presence of lateral restraint to the compression flange of the mullions (Fig. 2). However, the capacity of the mullion couple was found to be less than the yield capacity, thus the assumption of full lateral restraint to the mullions (Clift and Austin, 1989) is not applicable.

• Developed finite element models using

ABAQUS program can be used successfully


to predict the structural behaviour and

capacity of mullion couples.

Fig 1 Behaviour of mullion couple under negative wind action

Fig 2 Behaviour of mullion couple under positive wind action Note: S and C are shear centre and centroid of the mullions

References The Aluminium Association (AA) (2015). Aluminium Design Manual (ADM), Part 1: Specification for Aluminium Structures, The Aluminium Association, Arlington, VA, USA. Clift, C. and Austin, W. (1989). Lateral Buckling in Curtain Wall Systems. Journal of Structural Engineering, 115, pp. 2481-2495. Hui, C., Zhu, Y., Wang, B., Wang, Y. and Tao, W. (2015). Experimental and Theoretical Investigation on Mechanical Performance of Aluminium Alloy Beams in Unit Curtain Walls. Advances in Structural Engineering, 18, pp. 2103-2115. Mudie, S. and Rawlinson, S. (2010). Specialist costs: Building Envelopes. Magazine, Available at: http://building.co.uk [Accessed 20 February, 2017].

Further Information Thananjayan Sivaprakasam ([email protected])

Compression zone

Load transfer from

glass to mullions

S

⦻ ⦻

S ⦻ ⦻

C C

S

⦻ ⦻

S ⦻ ⦻

C C

Tension zone

http://building.co.uk/


Exploring the Energy Distribution of Large Open Floor Plan Compartment Fires for the Safe Design of Tall Buildings

19 Vinny Gupta


Page 41


Project background, objectives and goals At present, large open plan configurations are considered as a staple of the modern architecture environment as building designs have strayed further away from the concept of traditional compartmentalisation. Structural fire design of a building has been based on what is commonly known as the ’Compartment Fire Framework’, which was derived from decades of research into small cubic compartment under-ventilated fires [1]. The compartment fire framework sought to present a conservative quantification of the heat loads experienced by the structure of a building due to the energy released in a compartment fire. This framework has been standard practice in building designs; however, the framework relies on the assumption of small enclosed compartments. This is in direct contradiction with the evolution of the tall building, where large open plan spaces are the norm. The fire safety strategy of a building relies on three components: (1) enabling vertical compartmentation (confining the fire to one floor); (2) ensuring structural integrity beyond the burnout of the available fuel load; and (3) maintaining clear egress routes for the building occupants. All three components are intrinsically linked to being able to characterise the fire dynamics of the large compartment fire. Enabling vertical compartmentation is dependent on characterizing the amount of energy that can flow out from the compartment to the exterior of the building where the radiant heat can then be imposed onto facades or other compartments vertically. Designing the structure to withstand structural failure due is reliant on quantifying the spatial and temporal heating imposed onto the structural boundaries of the compartment. Designing clear egress routes is dependent on determining whether the hydrostatic force or the fire plume is driving the smoke into the stairs. Little research has been devoted to understanding the distribution of energy in design frameworks for open floor plan fires. This research seeks to propose a refined methodology that characterises the fire dynamics in large open floor plan compartments for a number of fire scenarios. The aim is to provide the designer with the tools to define specific fire scenarios to assist in the development of robust and explicitly quantifiable fire safety strategies.

Adopted methodology In 2013 and 2014, two full-scale fire experiments were undertaken [2] with an unprecedented quantity of instrumentation that generated a comprehensive data set in order to quantify the energy losses to the structural elements, and out of compartment vents into adjacent compartments or facades.

(a)

(b)

Fig 1 (a) Isometric view of the compartment detailing the internal dimensions and the directions and origin of the coordinate system used. (b) Diffusion flames forming and acting as the input fire within the compartment during the experimental runs.

Findings and application of results Recent work has been undertaken towards processing the data [3]. A methodology has been established based on conducting an energy balance of the compartment to quantify the thermal loads imposed to the structure. This work has proved that a conservation of energy is generally achievable for some scenarios, however significant divergence was found for others. This work aims to refining the methodology to establish the error bars of the


methodology in order to quantify the thermal loads to a structure. The proposed methodology is as follows:

1. Revisit the existing energy distribution analysis and refine the methodology to account for experimental errors and neglected heat losses (i.e. radiation)

2. Identifying and assessing the potential sources of uncertainty in the energy distribution analysis to establish appropriate error bars. These uncertainties in the methodology will be assessed using computational fluid dynamics modelling of the compartment fire experiments with further resolution.

3. Performing a spatial and temporal analysis of the energy distribution for a single fire scenario, in order to determine the patterns of structural heating for a fully-developed compartment fire, typical within the modern day tall building.

4. Extrapolating the methodology to other data sets to analyse the energy distributions for other fire scenarios in order to develop a set of guidelines and correlations to quantify the ratio of energy being transferred to the structure.

References [1] J. L. Torero, A. H. Majdalani, A. E. Cecilia, and A. Cowlard, “Revisiting the compartment fire,” Fire Saf. Sci., vol. 11, pp. 28–45, 2014. [2] J. P. Hidalgo et al., “An experimental study of full-scale open floor plan enclosure fires,” Fire Saf. J., vol. 89, no. February, pp. 22–40, 2017. [3] C. Maluk et al., “Energy distribution analysis in full-scale open floor plan enclosure fires,” Fire Saf. J., no. February, pp. 1–10, 2017.

Further Information Vinnty Gupta ([email protected])


Digital-Fabrication Structures for Prefabricated Infrastructure

20 Yousef Al-Qaryouti


Page 43


Project background, objectives and goals Prefabricated modular construction techniques have been identified by Australian researchers as an effective and popular method for low-cost and rapid postdisaster reconstruction (Gunawarden, et al., 2013). However, the National Disaster Recovery report released by the Regional Australia Institute (Tiernan, et al., 2013) emphasises that a heavy focus on immediate rebuilding of physical infrastructure to look normal can come at the expense of planning and adapting for long-term economic recovery. In the context of post-disaster reconstruction, existing prefabrication technologies are therefore both beneficial and detrimental. Benefits are seen as prefabricated systems allow low-cost, time efficient reconstruction with use of local labour (Gunawardena, et al., 2014). However, manufacture of prefabricated systems requires specialist expertise and facilities, so reconstruction investment is diverted out of the local economy to the detriment of long-term recovery. Digital fabrication is the use of generative computational methods and automated workshop machines to produce building components. It retains the streamlined construction of existing prefabricated systems but gives the designed substantial more control of the final structure and can utilised non-specialist and low-cost manufacturing plant. Such a system would enable the establishment of a distributed local or on-site manufacturing network to service short-term or rapid infrastructure demands. In-depth understanding of the structural behaviour of such systems in a necessary prerequisite for the successful application. The main purpose of this research is therefore to investigate digitally-fabricated structural systems suitable for resilient prefabricated infrastructure and develop an in-depth understanding of their structural performance.

Adopted methodology The research objectives are to investigate digitally-fabricated structural systems suitable for resilient prefabricated infrastructure and develop an in-depth understanding of their structural performance. This research is structured to develop the final knowledge required for technology application: an understanding of the structural behaviours of digitally-fabricated structures. Based on that, the research main scope is summarized with the following specific tasks:

Development of digital fabrication strategies for thin-walled sections.

Experimental, numerical and analytical investigations of the structural behaviour and failure modes of digitally-fabricated thin-walled sections.

Development of digitally-fabricated structural systems suitable for resilient prefabricated infrastructure.

Experimental, numerical and analytical investigations of the structural behaviour and failure modes of digitally-fabricated structural systems.

Findings and application of results The majority of projects that currently utilise digital fabrication strategies are bespoke, that is they are one-off structures. This research project will instead investigate digital fabrication strategies suitable for mass-produced, prefabricated construction, specifically prefabricated or modular housing. Digital fabrication has the potential to resolve the major limitation of prefabricated construction by utilising small, non-specialist fabrication facilities with a CNC capacity, rather than a single specialist fabrication plant. Use of a distributed manufacturing network enables local, remote, or on-site fabrication, has a reduced risk of production delays, a reduced dependence on manufacturing volume for production viability, and an increased capacity to respond to sudden or short-term demand. This research project aims to develop new types of digitally-fabricated structural systems suitable for resilient prefabricated infrastructure and develop an in-depth understanding of their structural performance. Firstly, a new structural system that utilises thin-walled timber sections suitable for kit-of-parts prefabrication construction have been developed. Experimental, numerical, and analytical investigations are conducted to understand the behaviour of the utilised orthogonal press-fit integral mechanical connections relative to traditional jointing methods. Then a second new type of structural system that utilises a timber-composite sandwich shell. New rotational press-fit joints and a hybrid material have been combined to deliver significant improvements on the spanning capacity and robustness of press-fit fabrication systems, whilst also offering new methods for simple, rapid assembly of shell structures. These advancements have been applied in fabrication of low-cost shell house that is shown in Figure (1).


Fig 1 Shell House

References Gunawardena, T. et al., 2014. Time efficient post-disaster housing reconstruction with prefabricated modular structures. open house international, 39(3). Gunawarden, T. et al., 2013. A holistic model for designing and optimising sustainable prefabricated modular buildings. Tiernan, A.-M., McGowan, J. & Drennan, L., 2013. From Disaster to Renewal: The Centrality of Business Recovery to Community Resilience, s.l.: Regional Australia Institute.

Further Information Yousef Al-Qaryouti ([email protected])


Seismic Performance of Prefabricated BRBY with Moment-resisting and Non-moment-resisting Beam-Column-brace Connections

21 Yuan Xu

Griffith University

Page 45


Project background, objectives and goals Prefabricated steel frames with buckling restrained braces (BRBs) have recently attracted considerable attention due to their swifter construction and superior hysteretic capability compared to the conventional frames. An improved prefabricated steel frame system with bolted beam-column connections and buckling restrained braces (BRBs) was proposed to meet the challenges of the conventional frames which commonly adopt combined bolting and welding connections. Full on-site prefabrication is the major improvement in the proposed system which provides rapid, safer construction and improved environmental performance.

Adopted methodology To evaluate the earthquake resistant performance of the proposed prefabricated system, both numerical and experimental investigations are developed in this project. In the numerical investigations, moment resisting and non-moment resisting beam-column-brace connections and the variation of the BRB areas along height, as well as two different building heights are considered.

For the numerical investigation, 3-bay frame models taking the form of the proposed system are studied in OpenSees considering moment resisting and non-moment resisting beam-column-brace connections and the variation of the BRB areas along height, as well as two different building heights (5-story and 9-story). Dynamic elastic-plastic time history analysis method was adopted in the numerical study.

An experimental program was undertaken on two half scaled 2-story standard frames which consist of one buckling retrained braced frame and non-moment resisting frame with different bolted only connections, and one single 2-story BRBF. The experimental models were first designed by software package SAP2000, then analyzed by finite element analysis package OpenSees, subsequently assembled and tested under cyclic loads.

Design method is developed for the proposed system. Especially, effectiveness of different design methods to determine the story-wise BRB area variation is evaluated based on the story shear force, story stiffness, inter-story drift and consistent BRB area.

Findings and application of results The results showed that the energy dissipation

capacity of the proposed system is reasonably good.

The structural system shows better performance when the story-wise distribution is proportional to the story shear forces.

The predictions obtained through OpenSees are in good agreement to their counterparts established experimentally.

References None

Further Information Yuan Xu ([email protected])


Experimental Investigation on Recycled Glass Powder as a Pozzolanic Cement

22 Zameer Kalakada

Griffith University

Page 46


Project background, objectives and goals The main aim of this research project is to study the pozzolanic performance of GP (glass powder) having a particle size smaller than 150 µm. The objectives of the study are:

The maximum percentage of GP used as cement replacement is 60% for last two decades. The present experimental work consists of replacing higher volume of GP (>60%) as cement replacement in order to check the suitability of GP as a binder solely rather than a cement replacement.

Conducting tests to ascertain the effect of GP size and the percentage replacement on fresh, mechanical and durability properties of the modified concrete

To determine the optimum cement replacement percentage and the best possible size of the GP in the current research

Adopted methodology Cement production, the binder in concrete has a huge environmental impact as it generates a large amount of greenhouse gas emissions. Gopalakrishnan and Govindarajan [1] suggested replacing cement with either a solid waste material or industrial by-product as a practical solution for decreasing the portland cement consumption. Use of industrial by-products like fly ash from coal combustion, or silica fume from silicon and ferrosilicon alloy production, or blast furnace slag from pig iron production, as cement substitution represents a value-added methodology to address the environmental issues. In recent years, use of recycled material such as waste glass has received an augmented attention in the concrete industry [2-4]. The procedure adhered in the current research is given below:

A detailed review of the literature is done on GP concrete to identify the knowledge gaps to be addressed in the current research. Experimental program is split into two stages.

Stage 1 comprised of a preliminary experimental

study to find the optimum replacement range to be followed in the subsequent stage and also to determine the aptness of the GP either as binder on its own or as cement replacement. An extensive concrete specimens of standard cylinder dimensions are prepared to investigate

the various material and strength properties by varying the GP content.

Stage 2 dealt with a detailed experimental program in the replacement range selected from stage 1. In addition to the standard cylinders for strength measurements, concrete prisms would be cast to determine the ASR (alkali-silica reaction) probability. Additionally, water absorption and chloride permeability would also be tested in order to quantify the performance of GP modified concrete in the durability perspective.

Findings and application of results There are multiple benefits of using recycled glass powder as cement replacement: firstly, using a waste material would reduce the load on the landfills; secondly, the total cost would be less as a recycled waste glass powder is replacing the costly cement and finally, the use of recycled glass powder would lead to sustainable construction as a consequence of a decrease in cement manufacturing. Majority of the research performed so far have concluded an optimum replacement of 20-30% as ideal for the GP to be used in place of cement in the production of the concrete. Since cement manufacturing is ominously affecting the environment the results of the present study might yield a higher substitution percentage and thereby leading to a substantial reduction in cement consumption. The present research is particularly significant to a country like Australia where in about 1.36 tonnes of glass packaging is consumed annually. According to a recent news report from Four Corners, hundreds of thousands of tonnes of glass are being stockpiled and landfilled instead of being recycled.

References [1] Gopalakrishnan, R. and D. Govindarajan, Compressive Strength and Electron Paramagnetic Resonance Studies on Waste Glass Admixtured Cement. New Journal of Glass and Ceramics, 2011. 01(03): p. 119-124. [2] Nassar, R.-U.-D. and P. Soroushian, Green and durable mortar produced with milled waste glass, in Concrete Research. 2012. p. 605-615. [3] Jain, J.A. and N. Neithalath, Chloride transport in fly ash and glass powder modified concretes – Influence of test methods on microstructure.


Cement and Concrete Composites, 2010. 32(2): p. 148-156.

[4] Wang, Z., C. Shi, and J. Song, Effect of glass powder on chloride ion transport and alkali-aggregate reaction expansion of lightweight aggregate concrete. Journal of Wuhan University of Technology-Mater. Sci. Ed., 2009. 24(2): p. 312-317.

Further Information Zameer Kalakada ([email protected])

Or Dr Jeung Hwan Doh ([email protected])



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