Analysis of Trusses – Zero Force Members | Engineering Mechanics | ME/ CE

by / Wednesday, 15 November 2017 / Published in Technical Corner

Real Life Application
For everyday occurrence, trusses are incorporated into numerous structures all around us, though we probably rarely notice. Here are just a few examples:
1.Bridges – Arch bridges, suspension bridges, cantilevered bridges.
2. Roofing – Practically all modern domestic housing, both timber and steel, employs trusses to span ceilings and support the roof cladding materials.
3. Cranes – The cranes employed in urban construction sites almost universally employ steel truss construction. Industrial lifting cranes in hangars, warehouses and factories also often employ truss construction to bridge substantial gaps while maximizing load carrying capacity.
4. Hangars – Every large warehouse building or aircraft hangar depends upon the rigidity and length of truss roof construction to span the enormous unsupported ceiling spaces.

Explanation
Zero force members:
a. These members do not support load
b. Increase stability during construction
c. Added support if loading conditions change
Two Member Rule: If only two members form a truss and no external load or support reaction is applied to the joint, the two members must be zero force member.
Three Member Rule: If three members form a truss joint for which two of the members are co-linear, the third member is a zero force member provided no external force or support reaction is applied to the joint.

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