Structural Detailing, Connections, and Fire Resistance
Detailing and connections
Detailing translates analysis into buildable drawings. Key concepts include load path continuity, ductility, and the difference between bearing, slip-critical, and tension connections. Welds and bolts have distinct limit states: bolt shear, bearing, tear-out, and weld throat capacity. Traps include ignoring edge distances, forgetting that a connection's capacity is the sum of its limit states (the lowest governs), and assuming a pinned connection provides moment restraint.
Fire resistance
Fire resistance is measured in hours and depends on material, protection, and detailing. Concrete and masonry have inherent resistance; steel needs spray fireproofing, encasement, or a protected assembly; wood gains resistance from charring. Candidates should understand the difference between a fire-resistance rating and a fire-protection rating for openings, and that penetrations must be protected to maintain the assembly's rating.
Worked rule of thumb
For a bolted connection with four bolts in single shear, each with a nominal shear strength of 20 kip, the connection shear capacity is 4 × 20 = 80 kip, but check bearing and tear-out on the plate: if plate bearing capacity is 18 kip per bolt, the governing capacity is 4 × 18 = 72 kip. Always take the lowest limit state, and verify edge distance.