弹性地基板模型在钢柱脚底板内力中的应用

Application of the Elastic Foundation Plate Model in the Sole Plate Stress Anlysis of Steel Frame Column

钢柱脚底板计算内力时,采用倒楼盖方法忽略基础刚度与相邻板件间影响,与板件的受力状态相差较大。为精确计算底板内力与变形,采用弹性地基板模型计算底板内力,考虑基础混凝土刚度对底板内力的影响,通过有限元软件壳单元建立分析模型,利用壳单元面外刚度考虑基础对底板内力影响。对比混凝土刚度取值的变化对底板内力影响,并与倒楼盖方法计算结果对比。分析结果对比,采用弹性地基模型确定底板厚度,并考虑相邻板件间影响的板厚计算结果与常用方法有较大差别。方法能够考虑混凝土刚度对底板内力影响,可为提高底板分析精度提供理论基础。

Normally,the method of inverted beam and girder floor can be used to calculate internal stresses in soles of steel columns.However,this method ignores the impact of the foundation stiffness between adjacent plates which leads to great difference between the actual stress state and the calculated stress state of plates.In order to obtain the internal stresses and deformation of based plates accurately,the elastic foundation plate model was applied,and the influence the foundation concrete stiffness brought to the stress state of the based plates was also considered,and a analytical model using shell element was modeled and analyzed through finite element software.In this analysis,out-of-plane rigidity of shell element was considered to analyze the influence that base brought to the internal stress state of the based plate.Several levels of concrete stiffness were taken into account in the model and results can be gained to analyze influence that stiffness changes resulted.and comparison of results were conducted between this stiffness-accounted FEM method and the method of inverted beam and girder floor.The comparison shows that the thickness of based plates determined by applying elastic foundation model,which consider the influence of internal stress of based plates,significantly differed from that of commonly used methods.The internal stress state reactions of based plates according to different concrete stiffness was oriented to consider and can be provided as a theoretical basis for improving the accuracy of the calculation of internal stress state for based plates.