Structural Design for Non-Structural Engineers

WHO ARE WE? IDC Technologies is internationally acknowledged as the premier provider of practical, technical training for engineers and technicians. We specialize in the fields of electrical systems, industrial data communications, telecommunications, automation and control, mechanical engineering, chemical and civil engineering, and are continually adding to our portfolio of over 60 different workshops. Our instructors are highly respected in their fields of expertise and in the last ten years have trained over 200,000 engineers, scientists and technicians. With offices conveniently located worldwide, IDC Technologies has an enthusiastic team of professional engineers, technicians and support staff who are committed to providing the highest level of training and consultancy. TECHNICAL WORKSHOPS TRAINING THAT WORKS We deliver engineering and technology training that will maximize your business goals. In today’s competitive environment, you require training that will help you and your organization to achieve its goals and produce a large return on investment. With our ‘training that works’ objective you and your organization will:

• Get job-related skills that you need to achieve your business goals • Improve the operation and design of your equipment and plant • Improve your troubleshooting abilities • Sharpen your competitive edge • Boost morale and retain valuable staff • Save time and money

EXPERT INSTRUCTORS We search the world for good quality instructors who have three outstanding attributes:

1. Expert knowledge and experience – of the course topic 2. Superb training abilities – to ensure the know-how is transferred effectively and quickly to you in

a practical, hands-on way 3. Listening skills – they listen carefully to the needs of the participants and want to ensure that you

benefit from the experience. Each and every instructor is evaluated by the delegates and we assess the presentation after every class to ensure that the instructor stays on track in presenting outstanding courses. HANDS-ON APPROACH TO TRAINING All IDC Technologies workshops include practical, hands-on sessions where the delegates are given the opportunity to apply in practice the theory they have learnt. REFERENCE MATERIALS A fully illustrated workshop book with hundreds of pages of tables, charts, figures and handy hints, plus considerable reference material is provided FREE of charge to each delegate. ACCREDITATION AND CONTINUING EDUCATION Satisfactory completion of all IDC workshops satisfies the requirements of the International Association for Continuing Education and Training for the award of 1.4 Continuing Education Units. IDC workshops also satisfy criteria for Continuing Professional Development according to the requirements of the Institution of Electrical Engineers and Institution of Measurement and Control in the UK, Institution of Engineers in Australia, Institution of Engineers New Zealand, and others.

THIS BOOK WAS DEVELOPED BY IDC TECHNOLOGIES

CERTIFICATE OF ATTENDANCE Each delegate receives a Certificate of Attendance documenting their experience. 100% MONEY BACK GUARANTEE IDC Technologies’ engineers have put considerable time and experience into ensuring that you gain maximum value from each workshop. If by lunchtime on the first day you decide that the workshop is not appropriate for your requirements, please let us know so that we can arrange a 100% refund of your fee. ONSITE WORKSHOPS All IDC Technologies Training Workshops are available on an on-site basis, presented at the venue of your choice, saving delegates travel time and expenses, thus providing your company with even greater savings. OFFICE LOCATIONS

AUSTRALIA • CANADA • INDIA • IRELAND • MALAYSIA • NEW ZEALAND • POLAND • SINGAPORE • SOUTH AFRICA • UNITED KINGDOM • UNITED STATES

idc@idc-online.com www.idc-online.com

Visit our website for FREE Pocket Guides IDC Technologies produce a set of 6 Pocket Guides used by

thousands of engineers and technicians worldwide. Vol. 1 – ELECTRONICS Vol. 4 – INSTRUMENTATION Vol. 2 – ELECTRICAL Vol. 5 – FORMULAE & CONVERSIONS Vol. 3 – COMMUNICATIONS Vol. 6 – INDUSTRIAL AUTOMATION

To download a FREE copy of these internationally best selling pocket guides go to:

www.idc-online.com/downloads/

Presents

Structural Design for Non-Structural Engineers

Rev 9

Website: www.idc-online.com E-mail: idc@idc-online.com

IDC Technologies Pty Ltd PO Box 1093, West Perth, Western Australia 6872 Offices in Australia, New Zealand, Singapore, United Kingdom, Ireland, Malaysia, Poland, United States of America, Canada, South Africa and India Copyright © IDC Technologies 2007. All rights reserved. First published 2007. All rights to this publication, associated software and workshop are reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, mechanical, photocopying, recording or otherwise without the prior written permission of the publisher. All enquiries should be made to the publisher at the address above. ISBN: 978-1-921007-24-8

Disclaimer Whilst all reasonable care has been taken to ensure that the descriptions, opinions, programs, listings, software and diagrams are accurate and workable, IDC Technologies do not accept any legal responsibility or liability to any person, organization or other entity for any direct loss, consequential loss or damage, however caused, that may be suffered as a result of the use of this publication or the associated workshop and software.

In case of any uncertainty, we recommend that you contact IDC Technologies for clarification or assistance.

Trademarks All terms used in this publication that are believed to be registered trademarks or trademarks are listed below:

Acknowledgements IDC Technologies expresses its sincere thanks to all those engineers and technicians on our training workshops who freely made available their expertise in preparing this manual.

Contents Preface iv 1 Structural engineering – an introduction 1

1.1 Introduction 1 1.2 Structural design – the process 3 1.3 Elements of structural design 4 1.4 Course objectives 5 1.5 Course outcomes 5

2 Structural systems & analysis of statically determinate structures 7 2.1 Classification of structures 8 2.2 Types of loads 11 2.3 Types of stress in structural members 15 2.4 Types of supports in structures 16 2.5 Equilibrium of bodies 17 2.6 Deformation of structures under loading 21 2.7 Structural classification based on degree of indeterminacy 23 2.8 Bending moment and shear force 27 2.9 Effect of moving loads 36 2.10 Analysis of pin-jointed frames 38 2.11 Influence lines 43 2.12 Conclusion 48

3 Principles of the Strength of Materials 49 3.1 Mechanical properties of the materials 49 3.2 Elasticity of the materials 49 3.3 Development of internal stresses 54 3.4 Flexural stresses in beams 56 3.5 Shear force and bending moment – the relationship 66 3.6 Bending shear stress 68 3.7 Horizontal and vertical shear – relationship 69 3.8 Bending shear stress – determination 70 3.9 Deformation of beams 75 3.10 The case of combined stresses 90 3.11 Analysis of columns 94 3.12 Conclusion 100

4 Analysis of Statically Indeterminate Structures 101 4.1 Structural classification based on the degree of indeterminacy 101 4.2 Principle of superposition 106 4.3 Analysis of statically indeterminate beams 107 4.4 Multi span or continuous beams 114 4.5 Slope deflection method 123 4.6 Moment distribution method 140 4.7 Influence line diagram for statically indeterminate structures 156 4.8 Conclusion 161

5 Design Theories 163 5.1 Stress-strain relationship for different materials 163 5.2 Design philosophies 166 5.3 Combination of loads 171 5.4 Theories of failure 172 5.5 Conclusion 172

6 Design of Steel Structures 173 6.1 Design of structures 173 6.2 Use of steel for structures 174 6.3 Properties of structural steel 176 6.4 Steel structural sections 177 6.5 Design of steel structures 178 6.6 Design of joints and fasteners for steel structures 179 6.7 Design of tension members 201 6.8 Design of compression members 207 6.9 Design of beams 219 6.10 Design of truss and allied structures 230 6.11 Conclusion 231

7 Design of Reinforced Cement Concrete Structures 233 7.1 Concrete – the material 233 7.2 Principle of reinforced concrete design 245 7.3 Design norms for reinforced concrete beams 258 7.4 Design of reinforced concrete slab 263 7.5 Design of reinforced concrete foundations 271 7.6 Design of axially loaded columns 279 7.7 Pre-stressed concrete – an introduction 285 7.8 Multistoried structures 290 7.9 Conclusion 292

8 Limit State & Plastic Design 293 8.1 Limit state theory 293 8.2 Design philosophy 294 8.3 RCC design by limit state 295 8.4 Steel structural design – plastic theory 304 8.5 Conclusion 314

9 Design and Construction of Masonry and Timber Structures 315 9.1 Masonry structures 315 9.2 Design of masonry structures 319 9.3 Timber construction 322 9.4 Strength of timber 326 9.5 Design of timber structures 327 9.6 Conclusion 330

10 Exercises 331

Preface Construction is the largest industry in the world and of course, anything that is constructed needs to be designed first. Structural Engineering deals with analysis and design aspects, the basic purpose of which is to ensure a safe, functional and economical structure. Throughout the designing process, the designer constantly interacts with specialists like architects, operational managers, etc. Once the design is finalized, the implementation requires the involvement of people to handle aspects such as statutory approvals, planning, quality assurance, material procurement, etc. The entire exercise can be undertaken in a highly coordinated way if everyone involved understands the ‘project language’, which is a combination of designs and specifications. To understand the language fully, it is necessary to appreciate the principles of structural analysis and design, and a book on this topic comes in handy here. Reading this book will help you gain the basic knowledge of structural engineering that includes principles of analysis of structures and their application, behavior of materials under loading, selection of construction materials and design fundamentals for RCC and steel structures. The emphasis has been kept on the determination of the nature and amount of stress developed under loads, and the way structures offer resistance to it. Being the most widely used construction materials, RCC and steel have been covered in detail, though masonry and timber have been described briefly as well. This manual is suitable for anyone associated with the construction industry. In view of the vastness of the sector, the following personnel would typically be able to gain immediate benefit out of the course.

• Building Inspectors • Project Managers • Construction Supervisors • Municipal Officials • Architects • Quantity Surveyors • Insurance Surveyors • Concrete Technologists • Reinforcement Detailers • Structural Fabricators • Building Maintenance Personnel • Structural Rehabilitation Staff

It is expected that this book will enable you to:

• Fully understand the role of a structural engineer • Comprehend the behavior of structural members under loading • Understand the concept of stress functions like tension, compression, shear and

bending • Use the basic concepts for analysis of statically determinate and indeterminate

structures • Analyze deformation of members under loading • Understand the significance of material properties in design • Undertake basic design of reinforced cement concrete structures • Undertake basic design of steel structures • Undertake basic design of masonry and timber structural members

v Structural Engineering 2

1

Structural engineering – an introduction

This chapter describes the basic objectives of the course and provides an insight to various aspects of structural engineering, including its scope and the fields of its application.

Learning objectives After completing the study of this chapter, you will be able to:

• Understand the role of the structural engineer. • Gain awareness of the processes governing structural engineering. • Appreciate the overall objective of the course.

1.1 Introduction Structural engineering is the branch of engineering that deals with the analysis and design of structures. For this purpose, a structure can be defined as an assembly of various physical components, combined in a way which makes them act together effectively against loading conditions. This process of assembling or combining various elements together is called construction. At times it may be possible for a structure to have only a single element, but such simple cases usually are rare. Bridges, buildings, transmission towers, trusses, water tanks, industrial sheds, etc., are some of the common types of structures that one frequently encounters in day-to-day life. Figures 1.1 to 1.4 on the following pages illustrate some structures under various classifications.

2 Structural Design for Non-structural Engineers

2

Figure 1.1 RCC Building – Under Construction

Figure 1.2 Bridge

Of the examples shown, building under Figure 1.1, bridge under Figure 1.2 and industrial shed of Figure 1.3 are those which one usually comes across more often. Whereas, concrete dome of Figure 1.4 are not so common to observe and can be termed as special purpose structures. The detailed classification of the structure has been described under the following chapter of the manual

Structural engineering – an introduction

3

Figure 1.3 Steel Framed Structure

Figure 1.4 RCC dome

1.2 Structural design – the process The basic purpose of the design of any structure is to ensure that it remains safe as well as functional under the most severe conditions of uses during its lifespan. The designer is expected to achieve this in the most economical way following scientific principles. The overall design operation follows well established set of processes. The functional planning takes into consideration the purpose for which the structure is being designed. It involves provision of areas and spaces including their interrelation, planning of utilities and services required,

4 Structural Design for Non-structural Engineers

4

providing for special features for the structure, etc. This process enables finalization of shape and plans of the structure. These layout plans get refined further as more experts get involved providing their inputs on specific issues. These layouts are extremely important since they enable the designer to select the optimum structural system as well as the construction materials. Further to deciding layout plan and structural arrangement, the designer starts working out the structural details of the individual components. This process involves determining the prospective loads applicable on the structure. The loads on the structure can be classified under several categories. This aspect has been dealt in detail in the following chapter of this manual. In modern times, however, the complexity involved in the design process has gone up due to the following reasons:

• Due to advancements in manufacturing processes, the variety of construction materials available has widened considerably in the last few years. The characteristics of materials also are improving rapidly. The challenge for designers to keep themselves abreast of these developments need not be emphasized.

• The rate of flow of information coming out of various studies and researches, be it on method of analyzing or on the behavior of materials, has increased substantially during recent years. The speed of their adoption within the engineering profession has also gone up. This means that designers are constantly updating themselves on new principles, philosophies, analysis tools, etc.

• Design tools, which include software programs too, are being refined and upgraded quite regularly.

With these technological advancements in the field of engineering, it is specialist structural engineers nowadays who handle the task of designing the structures. At the same time, the engineering applications are often interdisciplinary, involving the participation of several disciplines of engineering. Construction engineers have always been involved in the overall installation and maintenance of structures. In the case of buildings, the architect plans and decides on the features of the project. Therefore, it is imperative that construction engineers and architects have some basic knowledge of structural design and engineering in order to perform their functions effectively. For industrial structures, the end-user is usually a manufacturing engineer. The awareness of the structure’s behavior and limitations can help him decide on safe operational practices. Building inspectors, surveyors, etc., can also benefit from the knowledge of principles of structural engineering.

1.3 Elements of structural design An engineering design activity may be defined as the application of basic principles of science to ensure a safe, easy in practice and cost-effective solution for a situation. In accordance with it, the structural design exercise simultaneously applies the principles of the following streams of science:

• Mechanics • Strength of materials • Statistics

The principles of mechanics are applied to analyze the behavior of each and every component of the structure under specified loading conditions. For this purpose, the members are commonly assumed to be rigid bodies, thus ignoring any deformations caused by induced stress. The principles of mechanics help in establishing external load-reaction relationships for the structure and its members. It is useful in determining the best structural arrangement for a particular situation. The strength of materials is the science of relationship between an externally applied load and its internal effect on the bodies. For this, the bodies are no longer assumed to be rigid and their deformations under stresses are focused on. The application of the science of strength of materials helps in mainly determining the probable characteristic of material and through this, the optimum

Structural engineering – an introduction

5

construction material itself. Also obtained are the sectional properties of the members for a given structural system. In addition, these principles help in the determination of internal stresses too for the more complex structural systems. Statistics as a tool helps the design engineer work out the probability of a particular loading event occurring during the lifespan of the structure. With the help of this information, the engineer can identify the worst expected loading condition on a particular structural system during its entire lifetime. This is the most important set of information sought for the design process. Besides, statistics also helps in identifying the probable variation in the behavior of various construction materials, although the load conditions may remain similar. This information is useful to determine the allowance that needs to be considered towards the material characteristics in the given situation. The studies on construction materials, though, are almost always done independently with their results made available to the entire design fraternity that can apply them in the relevant situations. It is important to state that in the event of an uncommon design situation, it may become necessary for the design engineer or engineers to undertake this entire exercise prior to finalizing the design. Information technology is a facilitator that helps maintain design databases that are useful during routine design as well as in situations while new design philosophies are being implemented. In addition, with the help of the information technology, one also can undertake the conduction load simulations as well as modeling for the proposed structure, which can highlight certain behaviors as well as can validate the assumptions made. This is useful to finalize the form of the structure. The information technology assists the designer in even finalizing the drawings and design documents.

1.4 Course objectives The main objective of this course is to bring good awareness of structural engineering principles to those who have no formal training in the subject but are still involved with the building industry in certain roles. Apart from providing fundamental knowledge, the course also aims to impart reasonable degree of skill in solving analysis and design related problems in structural engineering.

1.5 Course outcomes • Acquiring basic knowledge of the properties and behavior of engineering materials. • Gaining the ability to analyze the stress-state of members under tension, compression,

shear, and bending. • Acquiring the ability to analyze deformation of members under loading. • Understanding concepts used for analyzing statically determinate and indeterminate

structures. • Understanding the basic design of reinforced cement concrete structures. • Understanding the basic design of steel structures. • Understanding the basic design of masonry and timber structural members.

6 Structural Design for Non-structural Engineers

6