# Structural Timber Design

## Structural Timber Design

The increasing recognition of timber as a structural material is reflected in
majority of design textbooks for undergraduate engineering students neg-
lect, to a large extent, the importance of timber as a structural and building
material. As a consequence, relatively few textbooks provide information on
the design of timber structures. Structural Timber Design is intended to
address this issue by providing a step-by-step approach to the design of all
the most commonly used timber elements and joints illustrated by detailed
worked examples. This is an approach which is recognised to be beneficial in
learning and preferred by most students.

The book has been written for undergraduate students on building, civil
and structural engineering and architectural courses and will be an
invaluable reference source and design aid for practising engineers and
postgraduate engineering students. It provides a comprehensive source of
information on practical timber design and encourages the use of computers

to carry out design calculations.

Chapter 1 introduces the nature and inherent characteristics of timber such
as defects, moisture content and slope of grain, and discusses the types of
timber and factors that influence their structural characte
includes a comprehensive review of the recently revised
Structural Use of Timber. The design philosophy of
its new approach to the strength class system and also the
factors affecting timber strength are explained.
Chapter 3 gives an overview of Mathcad, a computer software pro-
gramme used to carry out mathematical calculations, and details its
simplicity and the advantages that it provides when used for design calcu-
lations. The aim is to encourage readers to use computing as a tool to
increase their under-standing of how design solutions vary in response
to a change in one of the variables and how alternative design options can be
obtained easily and effortlessly. The design of basic elements is explained
and illustrated in Chapters 4 and 5, whilst the design of more specialised
elements such as glued laminated straight and curved beams and columns,
ply-webbed beams and built-up columns is illustrated in Chapters 6, 7 and 8

using numerous worked examples.

Timber has always been one of the more plentiful natural resources available
and consequently is one of the oldest known materials used in construction.
It is a material that is used for a variety of structural forms such as beams,
columns, trusses, girders and is also used in building systems such as piles,
deck members, railway foundations and for temporary foms in concrete.
Timber structures can be highly durable when properly treated and built.
Examples of this are seen in many historic buildings all around the world.

Timber possesses excellent insulating properties, good fire resistance, light
weight and aesthetic appeal. A great deal of research carried out since the
early part of this century has provided us with comprehensive information
on structural properties of timber and timber products'.
A knowledge of engineering materials is essential for engineering design.
Timber is a traditional building material and over the years considerable
knowledge has been gained on its important material properties and their
effects on structural design and service behaviour. Many failures in timber
buildings in the past have shown us the safe methods of construction,
connection details and design limitations.

This chapter provides a brief description of the engineering properties of
timber that are of interest to design engineers or architects. But it should be
kept in mind that, unlike some structural materials such as steel or concrete,
the properties of timber are very sensitive to environmental conditions. For
example, timber is very sensitive to moisture content, which has a direct
effect on the strength and stiffness, swelling or shrinkage of timber. A proper
understanding of the physical characteristics of wood aids the building of
safe timber structures"