Explanation:

A base plate is a structural component that is usually provided at the bottom of a truss to provide a stable foundation for the truss. In short roof trusses, base plates are provided to accommodate temperature-related expansion and contraction. The following are the reasons why base plates are provided in short roof trusses:

1. Expansion and contraction: Short roof trusses are exposed to temperature fluctuations, which can cause them to expand or contract. This expansion and contraction can cause the truss to move, which can result in structural damage. To prevent this from happening, base plates are provided to allow the truss to move without causing any damage.

2. Load transmission: Base plates are also provided to help transfer the load from the truss to the supporting structure. The base plate distributes the load evenly over a larger surface area, which reduces the stress on the supporting structure. This helps to prevent structural damage and ensures that the truss is stable.

3. Stability: Base plates are essential for the stability of short roof trusses. They provide a solid foundation for the truss, which helps to prevent it from shifting or moving. This ensures that the truss remains stable even in high winds or other adverse weather conditions.

4. Rigidity: Base plates also help to increase the rigidity of short roof trusses. The base plate is usually bolted to the supporting structure, which helps to lock the truss in place. This makes the truss more rigid and less prone to movement, which enhances its structural integrity.

Conclusion:

In summary, base plates are essential components in short roof trusses. They are provided to accommodate temperature-related expansion and contraction, to transmit load effectively, to provide stability, and to increase rigidity. Without base plates, short roof trusses would be more prone to structural damage and would be less stable and rigid.