Inelastic response and collapse behavior of steel tall buildings subjected to 3-D earthquake excitations

The objective of this research project is to investigate a 22-story building's performances during the September 19, 1985, Mexico earthquake by studying the hysteretic behavior, ductility factors of individual structural components, and the overall instability of the building. The hysteretic behavior has been studied for observing inelastic capacity and energy absorption of structural components and for developing hysteresis rules. The rules are established for bracing members, and truss-type girders and their web members, based on both the experimental data and the analytical finite segment technique. An analytical model is also developed to simulate the hysteretic behavior of local-buckled columns subjected to cyclic axial load and biaxial end-moments.;Extensive inelastic analyses have been performed for the building by using the multicomponent seismic input of actual Mexico City earthquake records. It was found that the system ductilities from floor 4 to 22 are greater than the building's design ductility of 4. Due to the load redistribution effects from the ductile-failed girders, the local bucklings are developed at the adjacent columns on the floors 2 to 4. Therefore, most columns on the floors 2 to 4 lost their load carry capacities and rigidities which then caused the building tilt and rotate. As a result, more columns on floors 5 to 7 developed local buckling and more bracing members buckled. It is believed that ductile failures of girders combined with the local bucklings of columns in the lower part of the building result in significant story drift, building tilt, P-...