Civil Engineering Professional Engineer Practice Exam

How are the members of a truss connected?

1. Welded together at seams

2. Bolted together with metal plates

3. Pinned together at joints

4. Entwined with cables

The correct answer is: Pinned together at joints

The members of a truss are typically connected at the joints using pinned connections. This type of connection allows the truss members to behave as a simple mechanism, where each member can freely rotate around the joint. This rotational freedom is essential because it allows the truss to distribute loads efficiently, maintaining equilibrium under various load conditions. Pinned connections can accommodate changes in geometry due to loads and are relatively simple to construct. They ensure that the members are not fixed in place but instead can pivot, which is crucial for the load transfer and overall stability of the structure. This characteristic helps prevent the introduction of internal moments, allowing the loads to be carried by axial forces within the members. In contrast, welded connections create rigid joints, which can introduce moments and restrict the rotation of the members, altering the way loads are distributed. Similarly, bolted connections with metal plates may introduce some rigidity, but they are often used in different contexts or with different load considerations. Lastly, entwining with cables is not a method used in standard truss construction and typically pertains to tension structures like cable-stayed bridges rather than the typical joint mechanisms seen in truss design.