Analysis Of Low-cycle Fatigue Behavior Of A Certain Semi-rigid Joint

After the Northridge Earthquake, the behavior of steel structures during strong earthquakes has received considerable attention. After the earthquake,flange-welded web-bolted connections were found to be fractured in more than 200moment-resisting steel frame buildings in the Los Angeles region. These popular fully rigid connections performed poorly unexpectedly.Many investigators have studied many alternative steel connections. The paper is dedicated to study the low-cycle fatigue behavior of a certain semi-rigid connection: the top- and -seat angle.Since semi-rigid connections, when subjected to moderate or strong earthquakes, become inelastic more quickly than their fully rigid counterparts, consideration of their energy absorption capacity is important. Under seismic ground shaking, the ability of the connection to dissipate energy will depend on the connection's capability to withstand low cycle fatigue. Constant amplitude reversed cyclic load tests were simulated with the aid of software MSC/Fatigue. Fatigue life predictions can be made for this class of connection using relationships analogous to the well-known Manson-Coffin strain-life equation for metals. For the top-and-seat angle connections considered in the paper, the large fatigue based plastic rotation capacity can be achieved.