Construction for Interior Designers

Roland Ashcroft

• Publisher: Routledge
• Year: 2013
• Print ISBN: 9781138628373
• eBook ISBN: 9781317897071
• Edition: 2
• Topic: Technology & Engineering
• Subtopic: Civil Engineering
• Index: Technology & Engineering

Construction for Interior Designers is a highly readable, comprehensive and informative text proving all the technical information required. The second edition has been fully updated to reflect the 1991 amendments if the 1985 Building Regulations and includes a new chapter on environmental issues affecting construction. Important concepts are explained from first principles with three-dimensional diagrams and informative tables. No previous knowledge of the subject is assumed.

Chapter 1

Structural principles

Introduction

A structure might be described as a series of components or ‘structural elements’ which, when fitted together, are capable of withstanding the loads and forces to which they are subjected.

A building is such a structure, being composed of a wide variety of components of different sizes and materials which, when fitted together, are capable of withstanding such loads and forces as:

• wind;
• the furnishings, people and machinery in the building (referred to as ‘superimposed’ loads);
• the considerable loads imposed by the weight of the building components themselves (referred to as ‘dead’ loads).

Clearly then, in the designing of a building and its interior, it is necessary to understand the way in which structures behave in relation to the materials and the construction techniques used.

Much of building design utilises the knowledge of established materials and components (such as bricks, timber joists, doors, etc.), which are fitted together by established techniques (for example the typical techniques used for forming a window opening, or for installing a staircase). Designers need to be sufficiently versatile to adapt and elaborate on these established principles, in order to fulfil the design requirements peculiar to a particular building/interior scheme. Sometimes, however, the designer will use less familiar techniques and materials in the design of a building/interior structure. In such circumstances, the designer might use the services of a structural engineer, who is trained to:

• calculate the loads and forces to which the structure will be subjected;
• calculate and design structural components of suitable size and of suitable material to withstand these loads and forces.

This chapter explains some of the terminology used in the study of the behaviour of structures, and considers some of the structural behaviour that might be expected in the components of a building/interior.

Definitions of basic terms

For a building structure to function properly, it should be capable of remaining stable when it is subjected to the various forces imposed on it. This does not mean that the building structure should be totally rigid, but that the degree of movement should be kept within tolerable limits. In fact, the material of any structure will move or deflect to some extent when subjected to a force.

Force

A ‘force’ acting on a structure, is the effect of weight on the structure, For example, a person weighing 70 kilograms (70 kg) standing on a floor, will push down on the floor with a force of 70 kilograms force (kgf). A strong wind blowing against the side of a wall will also exert a force of so many kilograms.

Forces due to the ‘mass’ (or weight) of objects are different from forces due to factors such as the wind, since they are subject to the effect of gravity. Gravity has the effect of pulling objects downwards at a rate of acceleration of 9.81 metres per second, per second (m/s²). Forces are measured in units of ‘newtons’ (N) or:

One newton is the force required to accelerate a weight of 1 kg by 1 m/s².

Consequently, an object of 1 kg weight which is subjected to gravitational force will exert a force of 9.81 N (or 1 kg ×9.81 m/s² = 9.81 N), In the case of the person standing on a floor, the force exerted will be 70 kg × 9.81 m/s² = 686.7 N

Structural stability relies on a structure, or part of a structure, resisting ‘active forces’ (imposed forces) by ‘passive forces’ (a balancing force produced within the structure).

For example, when a chair is placed on a floor, the chair kgs exert a downwards active force on the floor. In order to resist the active force, the floor produces an upwards passive force of similar magnitude. If a person sits on the chair, the active force is increased, and consequently the floor will provide an increased, upwards passive force, Passive force is produced in a structure by the material of the structure actually changing shape due to the exertion of an active force.

Figure 1.1(a) illustrates:

(i)	a block of material which is securely suspended from a structure;
(ii)	a similar block, which is placed on a secure floor structure. In both cases, the blocks are free from applied active forces, and the material of the blocks is relatively ‘at rest’.

Fig. 1.1(a)

(i)	Suspended block at rest
(ii)	Block at rest on floor

Fig. 1.1(b)

(i)	Active force applied to suspended block
(ii)	Active force applied to block on floor

The inset diagram of Fig. 1.1(a) illustrates diagrammatically a typical material at rest, where the atomic particles are held together by chemical bonds. In Fig. 1.1(b), an active force is applied to each of the blocks. In the case of (i) above, the active force pulls the material of the block, and a passive force is produced by the chemical bonds between the atomic particles being stretched. In the case of (ii) above, the active force pushes down on the block, and a passive force is produced by the chemical bonds between the atomic particles being foreshortened. The degree of elongation or foreshortening which occurs in the block will depend not only on the magnitude of the applied force, but also on the nature of th...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Preface to Second Edition
• Preface to First Edition
• Acknowledgements
• Chapter 1: Structural Principles
• Chapter 2: External Structure: Foundations and Walls
• Chapter 3: Roofs and Floors
• Chapter 4: Work to Existing Buildings
• Chapter 5: Internal Structure
• Chapter 6: Internal Furnishings and Fittings
• Chapter 7: Structural Materials: Timber, Metals, Concrete and Plastics
• Chapter 8: Internal Finishes and Materials
• Chapter 9: Environmental Issues
• Bibliography
• Index