Question

The influence line for force in member BC is

• A.
• B.
• C.
• D.

Answer 1

The correct option is C

When the unit load is anywhere on the right side of the joint D, no load will be transmitted to the joint C. Hence for this position of the unit load, there will be no force in the member BC. When the unit load is exactly at C the force in member BC will be equal to 1 (tensile). When the unit load is exactly at A, then also no load is transmitted to the joint C and hence for this position of the load also, there will be no force in the member BC.

Hence, Option d represents the ILD for force in member BC.