最小剪力系数及其调整方法对超高层建筑地震响应的影响

Influence of Minimum Shear Force Coefficient and Its Adjustment Methods on the Seismic Response of Super High-rise Buildings

超高层结构地震剪力响应由振型分解反应谱法得到的结果经常不能满足规定的最小剪力系数要求。为此,文章简述剪力系数的概念和调整方法,以具有不同剪力系数的两个模型对比分析结构弹性、弹塑性地震响应差异,探讨剪力系数对超高层结构地震响应的影响。以通过强度和刚度调整使最小剪力系数满足规范要求的两个模型,分析不同调整方法引起的结构响应的合理性。结果表明:满足最小剪力系数的结构的弹性基底剪力大、层间位移角较小,结构的弹塑性位移响应也较小,受力状态优于不满足最小剪力系数的结构,安全性得到了提高。结构弹性倾覆力矩需求和弹塑性基底剪力按刚度调整大于按强度调整;结构弹塑性最大顶点位移和层间位移角响应相差不大,但出现刚度大\,层间位移角也大的与抗震理论相悖的情况;在满足抗震要求的情况下,构件的受力状态则是按强度调整更优,构件截面更加经济合理。

Seismic shear force response of super highrise structures,calculated by the modesuperposition response spectrum method,cannot meet the requirements of the minimum shear force coefficient in code.Therefore,the concept and adjustment method of minimum shear force coefficient were sketched in this paper.Two models with different shear force coefficients were then adopted to analyze their differences in structural elasticity and elastoplastic seismic response,and discuss the influence of shear coefficient on the seismic response of supertall buildings.Finally,the minimum shear force coefficient of the two models was adjusted to satisfy code requirements through strength and stiffness adjustment methods;rationality of the structural response induced by different methods was then analyzed.Results demonstrated that,compared with the structure without a specified minimum shear force coefficient,the elastic base shear force of the structure with a specified minimum shear force coefficient was larger,and story drift ratio and elastoplastic displacement responses were smaller,i.e.,the safety of the structures was enhanced.The elastic overturning moment demand and elastoplastic base shear values of the two models,adjusted by the stiffness adjustment method,were greater than those adjusted by the strength adjustment method.Using the two methods,the maximum vertex displacement and story drift ratio were similar,although there was an abnormal situation wherein the story drift ratio changed with stiffness.In terms of meeting seismic requirements,stress condition of the components was superior and the component crosssection more reasonable and economical by using the strength adjustment method.