| The goal of this research is to develop a methodology for optimal aseismic design of structural systems via the use of passive energy dissipation devices. Triangular metallic plate and viscous dampers will be implemented in the structure to improve its seismic response. An experimental investigation is carried out to establish the material parameters for structural steel under cyclic loading at large strain amplitudes. A modified cyclic two-surface plasticity model is established using these parameters. Next a genetic algorithm and finite element analysis will be used to develop a methodology for the optimal placement of both the metallic and viscous dampers in the structure. The material model is implemented in the commercial finite element code ABAQUS as a user-defined subroutine.; The results of this work indicate that the enhanced cyclic two-surface plasticity model presented here compares well with experimental data in the literature and with the experiments carried out in this research. This model also appears to perform better than the cyclic plasticity model available in the commercial finite element code ABAQUS, version 5.8 for the range of problems considered here. Several case studies were carried out to demonstrate the optimal aseismic design using passive energy dissipation devices. The results suggest that the method developed for the placement and sizing of the dampers is viable for the aseismic design of both plane and space frame structures. Based on the Performance Index (PI), the structure, which utilizes both viscous and plate dampers in combination, performed better than those with viscous or plate dampers only. However, greater computational resources will be required than what is readily available today. This new procedure holds great promise for the design of structures with damping devices in a certain and an uncertain environment. It also bodes well for the future automation of the design process. |
