基于能量格式的模态Pushover方法及其应用

Energy-based format of modal pushover method and its appliction

提出一种基于能量增量直接获得模态Pushover分析中能力谱曲线的改进方法。基于线性和非线性系统的能量平衡方程证明,模态荷载作用下结构的总输入能量全部转化为某阶单自由度系统的总能量,并推导了增量模态荷载作用下系统能量增量与谱位移增量及谱加速度增量之间的关系,据此直接获得能力谱曲线。根据能力谱曲线得到各阶等效单自由度系统特性,结合弹塑性反应谱计算结构地震响应。运用该方法对一座高墩大跨连续刚构桥进行分析,并与常规Pushover方法进行对比。结果表明,该方法得到的能力谱曲线稳定性好,避免了常规模态Pushover方法中能力谱曲线的多义性和扭曲问题。

An improved method that directly establishes the capacity curve based on energy increments was submitted for modal pushover analysis(MPA).On the basis of the energy-balance equations of linear and nonlinear systems,it is proved that while the structure is loaded with modal related load,the total input energy will be fully transformed to the absorbed energy in the corresponding SDOF system.The relationships between the energy increments and the spectral displacement increments as well as the spectral acceleration increments were deduced,hence the capacity curve was directly obtained.The properties of the equivalent SDOF system were evaluated from the capacity curve,and the seismic responses were calculated making use of the capacity curve and response spectrum.A large span continuous frame bridge with tall piers in seismic zone was analyzed with the proposed method.The results show that the capacity curves obtained with the proposed method are more stable than those obtained with conventional method,thus the deficiency of multi-definition or distortion for conventtional method is corrected.