Examples in Structural Analysis First Edition

W.M.C.McKenzie

Preference :

Prior to the development of quantitative structural theories in the mid-18th century and
since builders relied on an intuitive and highly developed sense of structural behavior.
The advent of modern mathematical modeling and numerical methods has to a large
extent replaced this skill with a reliance on computer-generated solutions to structural
problems. Professor Hardy Cross1 aptly expressed his concern regarding this in the
following quote:
‘There is sometimes cause to fear that the scientific technique, the proud servant of the
engineering arts, is trying to swallow its master.’
It is inevitable and unavoidable that designers will utilize continually improving
computer software for analyses. However, it is essential that the use of such software
should only be undertaken by those with the appropriate knowledge and understanding of
the mathematical modeling, assumptions and limitations inherent in the programs they use.
Students adopt a variety of strategies to develop their knowledge and understanding of
structural behavior, e.g. the use of:
• computers to carry out sensitivity analyses,
• physical models to demonstrate physical effects such as buckling, bending, the
development of tension and compression and deformation characteristics,
• the study of worked examples and carrying out analyses using ‘hand’ methods.
This textbook focuses on the provision of numerous fully detailed and comprehensive
worked examples for a wide variety of structural problems. In each chapter, a résumé of
the concepts and principles involved in the method being considered is given and
illustrated by several examples. A selection of problems is then presented which students
should undertake on their own prior to studying the given solutions.
Students are strongly encouraged to attempt to visualize/sketch the deflected shape of
a loaded structure and predict the type of force in the members prior to carrying out the
analysis; i.e.
(i) in the case of pin-jointed frames identify the location of the tension and
compression members,
(ii) in the case of beams/rigid-jointed frames, sketch the shape of the bending moment
diagram and locate points of contra-flexure indicating areas of tension and compression.
A knowledge of the location of tension zones is vital when placing reinforcement in
reinforced concrete design and similarly with compression zones when assessing the
effective buckling lengths of steel members.