TRUSS DESIGN FACTORS OF SAFETY?
When I was asked to prepare this month’s column, I could not think of a better opportunity to answer a regularly posed question on truss design safety factors than in an issue focused on safety. It is inevitable that during a Truss Technician Training (TTT) course or a seminar, one of the questions asked is “How much safety is built into a truss?” We also continue to receive similar questions by email. One such question follows: Question: I am currently working on a project where a wood truss system was loaded with a heavy spring snow. I do not believe the load was beyond the truss’s design capacity. But how do you know? Is there safety built into wood trusses? If the trusses were loaded beyond their design capacity, it would not have been for a long duration. Any assistance would be appreciated. Answer: Structures and structural members must always be designed to carry some reserve load beyond what is expected under normal use. Under allowable stress design, safety is provided by usin
