Equilibrium: Free Body Diagram:

In previous unit, you have learnt about the technique of decreasing any system of forces to a force-couple system at some arbitrary point O. While this resultant force & the resultant couple both are equal to zero, the system is said to be in equilibrium. In this unit, you shall study the essential and sufficient conditions for the equilibrium of a rigid body. This shall enable you to find out the unknown forces applied to the rigid body in equilibrium or unknown reactions exerted on it by its supports. This shall help you to analyse any structure that is the first step in the design of structures.

Objectives

After learning this unit, you must be able to

• classify several types of supports and constraints,
• draw free body diagrams,
• understand conditions of equilibrium,
• Find out the unknown forces working on a body, and
• Find out beam reactions for various types of loads.