Toward seismic design of tall steel moment resisting frames using the theory of plastic mechanism control

Abstract

The kinematic approach and mechanism equilibrium curve in the rigid-plastic analysis framework are the basis of the theory of plastic mechanism control (TPMC). Applying this method for structural design will lead to a global collapse mechanism and prevent undesired collapse mechanisms. In this paper, to satisfy the TPMC conditions in tall moment-resisting frames (MRFs), linear programming (LP) is applied such that the TPMC conditions are defined as the optimization formulation. To investigate the effects of different structural constraints such as preventing the partial beam plastic hinge mechanisms (PBM), partial column plastic hinge mechanisms (PCM), and also to consider the strong-column weak-beam (SCWB) criterion in design MRFs by TPMC, a series of three (10, 15 and 20-story) MRFs is studied. Each frame is designed in the four different categories of the constraints: 1) PBM, 2) PBM + SCWB, 3) PBM + PCM, and 4) PBM + SCWB + PCM. The accuracy of the proposed design procedure is evaluated using pushover and nonlinear time history analyses. The results show that the designed structures reveal excellent seismic performance, and the global mechanisms are successfully achieved. The obtained nonlinear responses show that the seismic performances of the examined frames with different constraints are similar, and the PBM constraint is adequate for preventing undesired collapse mechanisms.