Fundamentals of optimum performance-based design for dynamic excitations

This paper presents a new method for optimization of the dynamic response of structures subjected to seismic excitation. This method is based on the concept of uniform distribution of deformation. In order to obtain the optimum distribution of structural properties, an iterative optimization procedure has been adopted. In this approach, 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 deformation is achieved. It is shown that, in general, for a MDOF structure, there exists a specific pattern for distribution of structural properties that results in an optimum seismic performance. It has been shown that the seismic performance of such a structure is optimal and behaves generally better than those designed by conventional methods. The application of the proposed method for optimum seismic design of different structural forms, such as truss-like structures and shear-buildings, is presented. The effects of fundamental period, target ductility demand, damping ratio, and seismic excitations on an optimum distribution pattern are investigated.