ldentify the 2 force members if any in the picture below To

ldentify the 2 force members (if any) in the picture below. To enter your answer: Identify the 2 force member by the 2 endpoints. For example, if there was a link that started at A and ended at B and its is a 2 force member, enter AB for your answer. The system will not accept other variations such as \"AB\" or A to B or A-B or \"the 2 force member is AB.\" If there are NO 2 force members, enter none. a/2 1.5a

Solution

AB is not a two force member, because B is not an internal hinge for member AB. B provides an external hinge for BC.

On the other hand CD is a two force member because for member CD, both of its ends are pinned, thus it can carry only an axial force, not bending moment.