Question

What is the beam called if it has two pinned support on both ends

Answer 1

A simply supported beam is a statically determinate structure. In order to be a statically determinate structure, it needs to have zero in statical indeterminancy. The roller support gives the beam an extra degree fo freedom , translation in the horizontal direction (change in length of the beam due to temperature effects, etc.), apart from translation in the vertical direction (i.e., the deflection of the beam, due to applied loads)

Number of equations = 3, F(h)=0,F(v)=0,M=0F(h)=0,F(v)=0,M=0

Number of unknowns = 3, three reaction forces, two at the pin support (both vertical and horizontal) and one at the roller support (vertical reaction)

Degree of indeterminancy = number of equations - number of unknowns = 3–3 = 0.