基于地震模拟振动台试验的铅芯橡胶隔震支座静力性能修正

Modified formula of the static performance parameters of lead rubber bearings based on shaking table test

目前我国在进行结构隔震设计时,橡胶隔震支座的力学性能参数是通过拟静力试验得到的,其在实际地震中的动力力学性能与拟静力试验的静力性能是否一致、差异的大小和程度是影响隔震结构安全性的关键问题,有必要开展深入研究。本文针对目前应用最为广泛的铅芯橡胶支座开展拟静力试验和模拟地震振动台动力试验的对比研究,分析不同地震波、不同剪应变作用下铅芯橡胶支座滞回曲线、屈服后刚度以及屈服力等力学性能参数的变化规律,进而提出考虑实际地震动力影响的静力性能修正公式。结果表明:拟静力试验与振动台动力试验相比,前者滞回曲线面积和力学性能参数均比后者大,说明目前隔震设计时直接采用静力试验的结果会夸大支座的耗能能力,给真实隔震结构带来安全隐患;而本文提出的静力性能修正公式则考虑了实际地震对支座的动力影响。本文的研究为工程隔震设计提供了参考,对于保证隔震结构的安全性和可靠性具有重要的理论意义和现实意义。

At present,the mechanical performance parameters of the rubber bearings are obtained by the pseudo-static test in the seismic isolation design of structures.But for the rubber bearings under actual earthquake,whether their dynamic performance are consistent with those of the pseudo-static test,the magnitude and degree of the difference are the key problems affecting the safety of the base isolation structures,so further research is needed.In this paper,the lead rubber isolation bearings which is widely used,was selected as the research objective,and the pseudo-static test and the shaking table test of lead rubber bearing were carried out and were compared firstly.The change laws of mechanical performances such as hysteresis curve,yield stiffness and yield force of lead rubber bearings under different earthquake records and shear strain were studied.At last,the modified formula of the static performance parameters considering actual earthquake dynamic effect was put forward.It can be seen that the hysteretic curve area and mechanical performance parameters of lead rubber bearings by pseudo static test are larger than those of shaking table test,which shows that the direct use of static test results in seismic isolation design will exaggerate the energy dissipation capacity of bearing and bring potential safety hazard to seismic isolation structure.The modified formula proposed in this paper takes into account the dynamic effect of actual earthquake on bearings.The research in this paper has important reference significance for seismic isolation design,and has important theoretical and practical significance for ensuring the safety and reliability of seismic isolation structure.