Steel Semirigid Column–Tree Moment Resisting Frame Seismic Behavior

Abstract

Semirigid moment-resisting frames can provide seismic resistance of buildings if the connections are engineered for ductile behavior. Column–tree construction can utilize splice assemblies to provide stable energy dissipation during lateral movement. Analytical studies showed that global performance was enhanced for a 4-story and 24-story building by switching from rigid to semirigid frame construction. An experimental test was conducted of a candidate connection made from T-shape hot-rolled sections for use in the building frames. The flange plates were tested with cyclic axial loads, approximating the expected loading of a flange splice when the connection rotates as a semirigid frame connection. Yielding of the reduced plate section and slip of the bolts provided stable and ductile behavior. Slip behavior of the bolts remained stable over several cycles and would allow significant rotation of a beam hinge. A comparison of the analytical demand and the experimental capacities obtained from the test specimen showed that the connection design would provide the capacities required during severe ground motions.