Design of Structures:

Structural design is an important requirement of a civil engineer. During his professional carrier he may be required to select a certain element or an entire structure made up of smaller elements which should be able to carry the given loads safely and perform its functions economically.

This is commonly carried out in various steps:

(a) A functional planning of the structure is the first step followed by a structural scheme, where the most satisfactory and economical solution of the problem is envisaged, and also the materials to be used and the type and arrangements of the structure is decided. This is done mainly by experienced engineers and requires a complete understanding of the client, needs and the limitations imposed through the site conditions.

(b) The next step is an estimation of the loads coming on the structure and a detailed structural analysis to be done in order to find out the stresses and strains to which the material is subjected under the loads. This is explained in your block of Strength of Materials and the first three units of this block.

(c) Finally the actual size and dimensions of the various elements are selected so as to safely carry the calculated stresses and strains which is in fact the actual structural design. This is, of course, followed by detailed structural drawings which will help the site engineer to fabricate, construct or erect the given structure. As you will see the actual choice of the proper structural element is a trial and error process as a random selection may be either unsafe or over safe. Hence, several trials may be needed to come to the correct size.