Types of Joints

All the structural members in framed buildings or trusses must be adequately connected together so that the applied loads are transferred safely to the ground surface. The types of connection or joints are basically divided into two: stiff and pinned joint.

Stiff Joint

This type of joint considered to have fixity at the point of connection and is rigid as it is sometimes called a rigid joint. The feature is that the flexure of one member meets at the joint has an effect on the other members. If it is perfectly stiff, then the angle between the members remains unaltered while rotation takes place.

Pinned Joint

It is sometimes called a hinged joint. As an example, many roof trusses and bridges are constructed using the pinned joint principles. These joints allow relative movement of the members and they cannot resist bending moments, unlike in stiff joints. Nowadays bolting and riveting are more common used, although the members cannot move relatively to one another, at some degree of rotation were allowed in practice. This is due to to the elasticity of the system and deformations of the members are relatively very small as this the common practice of assuming all joints in a truss to be pinned.