Effect of Uniform Height-Wise Distribution of Ductility Demand on Seismic Plastic Energy Demands of Generic Steel Frames

The effects of uniform deformation theory on plastic seismic energy demand spectra are intensivelyinvestigated. In this regards, several generic steel moment-resisting frames are optimized by using uniform deformation approaches subjected to a series of 40 far-fault ground motions.An iterative procedure has been adopted such that the structural properties are modified so that inefficient material is gradually shifted from strong to weak areas of a structure. This process is continued until a state of uniform ductility demand is achieved.Then, the maximum plastic (hysteretic) energy demand parameters are computed for different structures designed by optimum load pattern as well as code-based pattern, and the mean plastic energy spectra are compared. Results indicate that optimum seismic load pattern can significantly affect the plastic energy demands spectra. Moreover, the mean values of hysteretic energy demand for optimum structures are significantly larger than those of corresponding structures designed by code-based patterns, which are more pronounced for low level of inelastic behavior. This phenomenon indicates that in optimum structures the seismic energy dissipation in each structural element is maximized and the material capacity is fully exploited

Keywords:

Plastic Energy demand , Uniform deformation distribution , nonlinear dynamic analysis , performance-based approach , Ductility demand