Loads, Stresses and Structural Design:

Types of Load

All structures are subjected to loads. Those loads cause stresses and strains within the material of the structure. Through depending upon the nature of the material and its physico-mechanical characteristic, the magnitude of the stresses that a material could sustain is limited; and beyond which the material will fail. In the next section, you will be given the value of the permissible stresses in steel. The aim of structural design is to proportion the structure so that the stresses developed within it are within safe limits under any loading condition. At the same time, it should not be over-designed, that is the sections made unnecessarily large causing greater cost and heavier weight.

All structures are subjected to their own weight which is called self load or dead load. In addition to that, there are loads from external sources also, which are known as superimposed loads. These sources might be

• Wind and snow,
• Water current,
• Earthquake,
• Machines and their vibrations,
• Earth pressure, etc.