Study Of Performance Based Seismic Design For Energy Dissipation Structures With Viscoelastic Dampers

In the early 1990s, based on the damage characteristics of recent earthquakes, performance-based seismic design (PBSD) theory was proposed by the scholars of the United States, Japan, and other countries. It has become the mainstream direction of seismic design code in the 21st country.Viscoelastic dampers is a kind of typical of passive control devices, which did not need additional energy input. Control forces are produced with the vibration of the structure and the system will not become unstable. In addition, it has the following advantages: easy installation, low cost, good performance and wide application range.The main purpose of performance-based design method is to make the structural members to satisfy different performance level under different seismic risk level. Developments of energy dissipated technology make this purpose realize easily. This paper was focused on the seismic performance of structures with viscoelastic dampers and the main issues of performance-based seismic design theory for this kind of energy dissipation system. The performance-based seismic design procedure and capacity spectrum method are presented according to the characteristic of viscoelastic dampers and the requirements of the Chinese Code for Seismic Design of Buildings (GB50011- 2001).Based on the essence of Capacity Spectrum Method (CSM), a simple and practical design procedure was formed. According to the characteristic of viscoelastic dampers, simplified formulae of equivalent viscous damping ratio for structures with viscoelastic dampers are presented. Thus, the multi-degree-of-freedom nonlinear system is decomposed into several single-degree-of-freedom systems using modal Pushover analysis, and high modes effect can be considered. Taking into account high modes effect, the analytical result of interstory drifts of main elasto-plastic deformation regions was improved. The proposed procedure can also reduce the iteration times for calculation of equivalent damping ratios. Relations of elastic demand spectra based on equivalent damping ratio and inelastic demand spectra based on ductility factor are studied further in capacity spectrum method.Finally, an eight-story reinforced concrete frame with viscoelastic dampers is analyzed as case study. The programs of the nonlinear time history analysis are also compiled by MATLAB, and analysis the examples.The comparison of the results indicated that this procedure is reasonable and effective. Compared with traditional methods, this procedure is simple, intuitionistic and easy to programs.