弱耦联体系地震响应的隔离分析求解

FREE-BODY BASED SOLVING STRATEGY FOR SEISMIC RESPONSES OF WEAKLY-COUPLED SYSTEM

弱耦联体系由一系列支柱结构及柔性连接件组成,结构整体性差,支柱与连接件材料的阻尼特性差异显著。这两个特点造成了采用结构整体振型以及比例阻尼的常规抗震计算方法在处理弱耦联问题时的局限性。因此,从支柱及连接件的隔离体分析出发,构建考虑二者非比例阻尼的运动控制方程,并在频域对耦合的方程进行求解,从而避免对整体振型正交性条件的使用。通过弱耦联体系实例的振动台试验验证,在不同地震动输入下,此方法计算的顶部最大位移误差在1.2%~5.8%。与传统振型叠加法计算结果的对比分析证明:采用整体振型以及比例阻尼会高估弱耦联体系支柱间的耦联作用,从而造成更大的系统性误差。

The weakly-coupled system consists of a series of supporting structures interconnected by flexible connection components and is characterized by weak structural integrity and massive discrepancy between material damping of the supporting structure and connection component. Such two characteristics result in some limitations of the conventional seismic analysis methods using global vibration modes and proportional damping for the weakly-coupled system. In light of these, based on free-body analysis of the supporting structure and connection component, the equations of motion, which consider their inconsistent damping properties, were formulated in this study. To avoid potential errors brought by decoupling of the orthogonality conditions of global vibration modes, the equations of motion were solved in the frequency-domain. This method was validated by the shaking table test of an exampled weakly-coupled system, and the maximum errors of the top displacement with different input ground motions were between 1.2% and 5.8%. Moreover, comparisons between the present method and conventional modal superposition method proved that the usage of the global vibration modes and proportional damping can overestimate the coupling effect among supporting structures and cause larger systematic errors.