近场多脉冲地震动作用下组合隔震结构抗震性能分析

The Seismic Behavior Analysis of Near-field Multi Pulse Ground Motion on Composite Isolated Structure

采用速度脉冲分量与宽频分量相结合的方法,拟合了近场多脉冲地震波;构建了组合隔震结构的计算模型和运动方程,对组合隔震结构的动力响应进行仿真分析。结果表明:通过增设黏滞阻尼器可以有效控制结构的地震响应,减小隔震层位移,改善结构的受力。对于提高近场多脉冲地震作用下结构的安全性有显著作用。

In recent years, the base isolation technique has been widely accepted and promoted as one of the most effective approaches for earthquake resistance due to its security and reliability for use with near-field earthquakes. Some researchers have studied and discussed the influence of va- rious parameters including peak ground acceleration/peak ground velocity （PGV/PGA）, input energy, peak values, and duration of the near-field earthquakes on the earthquake-resistant per- formance of constructions. Multi-pulse near-field earthquakes have a larger influence on the base isolation structure than do single-pulse near-field earthquakes; thus, more attention has been paid to the security problems of constructions under this working condition. The focus of this paper, therefore, is an isolation project in the northwest district in which the elastic-plastic response time history of near-field earthquakes was analyzed, and a viscous damper was added to improve the current earthquake-resistant performance of the base isolation structure. In this paper, a multi-pulse seismic wave in a near-field earthquake was simulated and syn- thesized using a MATLAB procedure and a combination of velocity impulse and broadband com- ponents. The design scheme for the X-type symmetrical distributed viscous damper was selected to reduce the additional internal force effect of the energy-dissipating brace on the beam and col- umn construction of the structure. On this basis, a computational model and equation of motion for the composite isolated structure was established. The earthquake response of the base andcomposite isolated structures was measured under three working conditions including the tro wave, the near-field wave of the Chi-chi earthquake recorded at Tcu075 observation and an artificially fitted multi-pulse wave. El Cen- station, Theoretical analysis and numerical simulation revealed the peak valueacceleration of the base isolation structure was larger than that of the composite isolated structure. The input energy of the structure increased progressively. In particular, the input energy of the seismic wave in the multi-pulse near-field earthquake was greater than that of the Chi-chi wave and significantly grea- ter than that of the E1 Centro wave. When an earthquake occurred, components with many struc- tures entered the plastic stage owing to the input energy factor, which resulted in substantial weakness. However, the time-history curve for energy consumption of the damper revealed that the damper fully exerted its energy consumption under each working condition. The composite i- solated structure was able to fully consider the energy consumption of the structure under the ac- tion of the near-field earthquake and multi-pulse near-field earthquake to guarantee the security of the structure. Designers and engineering technicians have focused on displacement of the isolation layer and the bottom column axial force. After discussion and analysis, it has been determined that the complex isolation design is more feasible under the action of the near-field earthquake. This study examined the earthquake responses of structures under different working condi- tions including the function of multi-pulse near-field seismic oscillation on base isolation struc- tures and the damping effect of composite isolated structures after addition of the damper. The results are summarized in the following points： 1. The energy consumption of the complex isola- tion of a composite isolated structure has distinct advantages that can effectively reduce the num- ber of components in the plastic structural system and improve the earthquake resistance ability of the structure in the near-field multi-pulse earthquake process; 2. Under the action of a near-field earthquake, the displacement of the base isolation structure in the isolation layer becomes exces- sively large; and 3. The composite isolated structure can effectively reduce the axial force of the bottom column.