What type of force is applied to the top cord of a truss?

In a truss system, the top chord experiences compression due to the loading applied on the truss. When a load is introduced to the truss, it tends to push down on the truss structure. This creates a situation where the top section of the truss is compressed, or squeezed together, especially as the load is distributed down through the truss to the supports at either end.

In contrast, the bottom chord of the truss typically experiences tension, where forces pull it apart. Therefore, it is essential to recognize that the respective chords of the truss are subject to different types of forces based on their positioning and the nature of the loads they carry. Understanding these concepts is crucial for fire service personnel to assess structural integrity during emergencies where trusses may be present.

The other types of forces mentioned—shear and bending—relate to different structural behaviors and responses to load but do not correctly describe the primary force acting on the top chord of the truss in this context. Shear typically occurs at connections where the load is transferred across members, while bending refers to the angular distortion of a structural element under loading.