考虑地面运动的多模态静力弹塑性分析方法

Considering ground motion to establish equivalent single degree of freedom systems for modal pushover analysis procedure

为了提高静力弹塑性分析方法的计算精度,克服多模态静力弹塑性分析方法(MPA)在计算等效单自由度时不能考虑地面运动,加载制度仅由结构特性决定的缺点.提出了考虑地面运动建立等效单自由度的多模态静力弹塑性分析方法,通过对12层钢筋混凝土标准框架振动台模型,分别采用非线性时程分析方法、建议方法以及MPA方法进行了计算,分析在非线性发展过程中影响模态坐标之间耦合程度的影响因素,对比计算结果、指出地面运动对高阶振型相对激励的大小程度,即地震动的频谱特性是影响计算结果的主要因素,验证了建议方法的有效性和适应性.表明建议方法计算精度较MPA方法有了一定的提高,特别是改善了MPA方法对高阶振型敏感的地面运动失效的缺点.建议方法可改善静力弹塑性分析方法在地面运动对高阶振型相对激励较大时的计算精度,可增加静力弹塑性分析方法的使用范围.

This paper presented a newly-developed analysis procedure for establishing equivalent single degree of freedom systems （ESDOF）, based on the modal pushover analysis procedure with higher precision. The modal pushover analysis procedure was limited in terms of its inability to account for ground motion when establishing ESDOF. The suggested method overcomes the shortcoming. This method is characterized by its high efficiency of calculation and clear physical meaning, which eliminates the need to calculate modal combination step by step. And it was validated by calculating a shaking table test of a 12-storey reinforced concrete frame model. The structure model was calculated separately using nonlinear time history method, the method introduced herein and conventional modal pushover analysis procedure. Through the comparison of the calculation results, it was found that the higher-mode relative excited magnitude by ground motion is the main reason for modal coupling. And the suggested method yields higher precision than conventional modal pushover analysis procedure, especially for high frequency ground motion. So it has good adaptability.