Basic Structures

Philip Garrison

• Publisher: Wiley-Blackwell
• Year: 2016
• ISBN:
  9781118950852
• Edition: 3
• Topic: Technology & Engineering
• Subtopic: Civil Engineering
• Index: Technology & Engineering

Basic Structures provides the student with a clear explanation of structural concepts, using many analogies and examples. Real examples and case studies show the concepts in use, and the book is well illustrated with full colour photographs and many line illustrations, giving the student a thorough grounding in the fundamentals and a 'feel' for the way buildings behave structurally. With many worked examples and tutorial questions, the book serves as an ideal introduction to the subject.

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What is structural engineering?

Introduction

In this chapter you, the reader, are introduced to structures. We will discuss what a structure actually is. The professional concerned with structures is the structural engineer. We will look at the role of the structural engineer in the context of other construction professionals. We will also examine the structural requirements of a building and will review the various individual parts of a structure and the way they interrelate. Finally you will receive some direction on how to use this book depending on the course you are studying or the nature of your interest in structures.

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Structures in the context of everyday life

There is a new confidence evident in major British cities. Redundant Victorian industrial structures are being converted to luxury apartments. Tired old 1960s shopping centres are being razed to the ground, and attractive and contemporary replacements are appearing. Public housing estates built over 40 years ago are being demolished and replaced with more suitable housing. Social shifts are occurring: young professional people are starting to live in city centres and new services such as cafés, bars and restaurants are springing up to serve them. All these new uses require new buildings or converted old buildings. Every building has to have a structure. In some of these new buildings the structure will be ‘extrovert’ – in other words the structural frame of the building will be clearly visible to passers-by. In many others, the structure will be concealed. But, whether seen or not, the structure is an essential part of any building. Without it, there would be no building.

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What is a structure?

The structure of a building (or other object) is the part which is responsible for maintaining the shape of the building under the influence of the forces, loads and other environmental factors to which it is subjected. It is important that the structure as a whole (or any part of it) does not fall down, break or deform to an unacceptable degree when subjected to such forces or loads.

The study of structures involves the analysis of the forces and stresses occurring within a structure and the design of suitable components to cater for such forces and stresses.

As an analogy, consider the human body, which comprises a skeleton of 206 bones. If any of the bones in your body were to break, or if any of the joints between those bones were to disconnect or seize up, your injured body would ‘fail’ structurally (and cause you a great deal of pain).

Examples of structural components (or ‘members’, as structural engineers call them) include the following:

• steel beams, columns, roof trusses and space frames
• reinforced concrete beams, columns, slabs, retaining walls and foundations
• timber joists, columns, glulam beams and roof trusses
• masonry walls and columns.

For an example of a densely packed collection of structures, see Fig. 1.1.

Fig. 1.1 Lower Manhattan skyline, New York City.
This is one of the largest concentrations of high-rise buildings in the world: space limitations on the island of Manhattan meant that building construction had to proceed upwards rather than outwards, and the presence of solid rock made foundations for these soaring structures feasible.

What is an engineer?

As mentioned in the introduction, the general public is poorly informed about what an engineer is and what he or she does. ‘Engineer’ is not the correct word for the person who comes round to repair your ailing tumble dryer or office photocopier – nor does it have much to do with engines! In fact, the word ‘engineer’ comes from the French word ingénieur, which refers to someone who uses their ingenuity to solve problems. An engineer, therefore, is a problem-solver.

When we buy a product – for example, a bottle-opener, a bicycle or a loaf of bread – we are really buying a solution to a problem. For instance, you would buy a car not because you wish to have a tonne of metal parked outside your house but rather because of the service it can offer you: a car solves a transportation problem. You could probably think of numerous other examples:

• A can of baked beans solves a hunger problem.
• Scaffolding solves an access problem.
• Furniture polish solves a cleaning problem.
• A house or flat solves an accommodation problem.
• A university course solves an education problem.

A structural engineer solves the problem of ensuring that a building – or other structure – is adequate (in terms of strength, stability, cost, etc.) for its intended use. We shall expand on this later in the chapter. A structural engineer does not usually work alone: he is part of a team of professionals, as we shall see.

The structural engineer in the context of related professions

If I were to ask you to name some of the professionals involved in the design of buildings, the list you would come up with would probably include the following:

• architect
• structural engineer
• quantity surveyor.

Of course, this is not an exhaustive list. There are many other professionals involved in building design (e.g., building surveyors and project managers) and many more trades and professions involved in the actual construction of buildings, but for simplicity we will confine our discussion to the three named earlier.

The architect is responsible for the design of a building with particular regard to its appearance and environmental qualities such as light levels and noise insulation. His starting point is the client’s brief. (The client is usually the person or organisation that is paying for the work to be done.)

The structural engineer is responsible for ensuring that the building can safely withstand all the forces to which it is likely to be subje...

Table of contents

• Cover
• Title Page
• Table of Contents
• Acknowledgements
• Introduction
• 1 What is structural engineering?
• 2 Learn the language
• 3 How do structures (and parts of structures) behave?
• 4 Force, mass and weight
• 5 Loading – dead or alive
• 6 Equilibrium – a balanced approach
• 7 More about forces
• 8 Moments
• 9 Reactions
• 10 Different types of support – and what’s a pin?
• 11 A few words about stability
• 12 Introduction to the analysis of pin-jointed frames
• 13 Method of resolution at joints
• 14 Method of sections
• 15 Graphical method
• 16 Shear force and bending moments
• 17 This thing called stress
• 18 Direct (and shear) stress
• 19 Bending stress
• 20 Combined bending and axial stress
• 21 Structural materials
• 22 More on materials
• 23 How far can I span?
• 24 Calculating those loads
• 25 An introduction to structural design
• 26 More on structural types and forms
• 27 An introduction to deflection
• 28 Shear stress
• 29 Buckling and torsion
• 30 Frames and three-pinned arches
• 31 Virtual work
• 32 Squares and circles of stress
• 33 Trusses (no numbers)
• 34 Plastic analysis
• Further reading
• Appendix 1: Weights of common building materials
• Appendix 2: Conversions and relationships between units
• Appendix 3: Mathematics associated with right-angled triangles
• Appendix 4: Symbols
• Appendix 5: A checklist for architects
• Appendix 6: Getting more out of civil engineering
• Index
• End User License Agreement