If any part of a truss fails, what happens to the entire truss?

• A. The truss fails completely
• B. The affected area fails only
• C. The system compensates and no failure occurs
• D. Only the connected members fail

Answer: (A)

In a truss, loads are carried through a connected network of members that share the load along the joints. That makes the truss a single system: if one member fails, the path carrying the load is disrupted and the forces that were carried by that member must be taken up by others. Often, those remaining members aren’t able to absorb the extra load without exceeding their capacity, which leads to a loss of stability and progressive collapse of the entire truss. Under fire conditions, heating weakens members and joints, accelerating this sequence, so a single failure can trigger a complete failure of the truss.