Question

In calculating the vertical displacement of point D due to a P force acting at B, a student uses the principle of virtual work. Before he substitutes his analysis into the deflection equation for virtual work and part of the procedure for analysis, this is what he does... Choose the correct answer. D 4 ft B 3 ft 3 ft VP He solves for all the internal loads due to Pat B. He solves for all the internal loads due to P at B and then re-analyzes the truss again with the Pload but by placing a unit load at B. He solves for all the internal loads due to P at B and then re-analyzes the truss again without the Pload but by placing a unit load at D. He solves for all the internal loads due to Pat B and then re-analyzes the truss again without the P load but by placing a unit load at B. He analyses the structure Once when both of the load P acting at B and a unit load is acting at D. He solves for all the internal loads due to a unit load at D. He solves for all the internal loads due to a unit load at B. He solves for all the internal loads due to P at B and then re-analyzes the truss again with the P load but by placing a unit load at D.

Answer 1

As P is acting on B all internal loads due to P at B will be calculated.

Also as he need to find the deflection of point D, he should be applying virtual load at D only. Not considering any load P acting at B.

So option no 3 is the correct option to choose.