钢筋混凝土掉层框架结构多点输入地震响应特征分析
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TU311.3;TU323.5

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国家自然科学基金(51878101、51638002)


Characteristic analysis of multipoint input seismic response of reinforced concrete frame structures supported by stepped foundations
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    摘要:

    山地建筑不同标高基础的地震动存在差异,其对山地建筑地震响应的影响程度有待研究。以自贡地形台阵为背景,以该台阵采集的汶川地震记录为输入,设计4组空间钢筋混凝土(RC)掉层框架结构。分别按上接地地震动的一致输入、下接地地震动的一致输入、上接地与下接地不同地震动的多点输入开展了算例结构的弹性和弹塑性时程分析。将一致输入结构响应与多点输入结构响应之比定义为结构地震响应差异系数,从结构地震响应差异系数、破坏特征等方面分析了多点输入对岩石地基基础上的空间RC掉层框架结构地震响应的影响。结果表明:弹性分析时,基本周期较长的RC掉层框架结构侧向变形和层剪力的地震响应差异系数在0.85~1.12之间,基本周期较短结构的侧向变形和层剪力的地震响应差异系数在0.38~1.22之间,按一致输入地震动设计的RC掉层框架结构可能偏不安全;弹塑性分析时,多点输入下RC掉层框架结构的地震响应与一致输入下的有明显差异,最小差异系数可到0.27;在极罕遇地震作用时,多点输入下RC掉层框架结构底部的破坏状态比一致输入下严重,宜对其掉层部分和坎上1层进行适当的抗震加强。

    Abstract:

    The ground motions of foundations in mountainous regions vary at different elevation, and the degree of impacts on the seismic response of buildings in the areaneeds to be studied. By forming the Wenchuan earthquake records from Zigong observation array as the inputs, four RC (reinforced concrete) frame structures supported by stepped foundations were designed based on Chinese National Standard for seismic design of buildings. The elastic and elastoplastic time history analysis of the structure of the calculation example was carried out by inputting the ground motion signal at upper surface of the foundation, at lower surface or the multiple points at both surfaces. Structural seismic response difference coefficient is defined as the ratio of the response to the single excitation signal at one surface over the response to the multi-point excitation inputs at both surfaces. The influence of multipoint input on the seismic response of the spatial RC frame structures supported by stepped foundationsis analyzed in the aspects of structural seismic response difference coefficients and failure modes. The results are following:In the elastic analysis, the difference coefficient of seismic response of lateral deformation and storey shear of RC frame structure with long 1stnatural period is between 0.85 and 1.12, while the value is between 0.38 and 1.22 for similar structures with relatively shorter 1st natural period. Thus, the RC frame structures supported by stepped foundationsdesigned only based on the single ground motion signal on one surface may be unsafe. In the elastoplastic analysis, the seismic response of the RC frame structures supported by stepped foundations with both long and short periods under multi-input is obviously different from that under uniform input, and the minimum difference coefficient can reach 0.27; The failure state of the bottom of the RC frame structure under multi-point input is more severe than that under single inputunder the extremely rare earthquake. Proper seismic strengthening should be carried out for the step part and the first floor above the sill of the RC frame structures supported by stepped foundations.

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刘立平,李瑞锋,李维斯,姜伟,李英民.钢筋混凝土掉层框架结构多点输入地震响应特征分析[J].土木与环境工程学报(中英文),2020,42(6):71-80.

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  • 收稿日期:2019-12-20
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  • 在线发布日期: 2020-11-26
  • 出版日期: 2020-12-31