In a Pratt truss, what is the primary function of the vertical members?

In a Pratt truss, the vertical members primarily function to support vertical loads, such as those from the weight of the truss itself and other loads acting on the truss during its use. The design of a Pratt truss includes vertical members that are strategically placed to effectively carry these loads. When subjected to vertical forces, the vertical members are primarily in tension, which is a key characteristic of Pratt trusses. The sloping members of the truss are designed to handle compression, but the role of the verticals is crucial in maintaining the structural integrity by ensuring that vertical loads are efficiently transferred down to the supports.

The tension in the vertical members allows for effective load distribution throughout the truss structure, helping to maintain stability and preventing sagging. This design is particularly effective for spanning larger spaces, which is why Pratt trusses are commonly used in bridges and other large structures.