STRESS AND STRAIN –LOADS

Before any engineering structure can be used, we have to ensure that it is able to sustain the load acted on it throughout its life. If the components or members are in equilibrium, the resultant of the external forces will be zero.



LOADS
If a cylindrical bar is subjected to a direct pull or push along its axis as shown in figure below, then it is said to be subjected to tension or compression.

Example of tension --> a force present in towing ropes or lifting hoists.
Example of compression --> à forces in the leg of a chair as we sit on it or forces in the support pillars of building.

TYPES OF LOADINGS

TYPES OF LOADING	EXAMPLES
Static or dead loads	Non fluctuating stationary loads. (generally caused by self-weight of structures)
Live loads	Moving loads, for example vehicular loads on bridges.
Impact or shock loads	Loads caused by sudden blows.
Fatigue, fluctuating or alternating loads	Loads where magnitude and direction change with time.