基于轴力权重的有侧移钢框架整体稳定性的实用算法

Practical calculation method for the overall stability of a sway steel frame based on applying the weight on the axial force

针对规范计算长度系数法逐个构件验算确定钢框架整体稳定的不便以及无法考虑同层柱间的相互支援以及层与层的支援作用的不足,该研究基于弹簧-摇摆柱模型阐述了有侧移框架结构失稳的物理意义。通过结构转换的概念,首先利用框架重复单元求解楼层抗侧刚度及利用临界刚度比系数求解楼层荷载刚度,然后将楼层抗侧刚度和荷载刚度进行整体组装,将求解钢框架整体稳定临界承载力的二阶计算转化为确定框架整体抗侧刚度的一阶问题,最后基于轴力权重加权平均的方法考虑楼层刚度激活程度,获得可直接计算钢框架临界承载力的计算公式。该公式能够判断结构的薄弱层,可以定量地计算楼层之间相互支援程度,避免了计算长度系数法可能因无法考虑两种支援作用造成的不合理设计。算例计算结果表明,该方法具有很好的精度及准确性,可供工程设计使用。

In view of the inconvenience in determining the overall stability of frames by the standard calculation length method for one by one component checking and the disadvantage of not being able to consider the mutual support between the same layer columns and the inter-story interaction,the physical meaning description of the instability of sway steel frames was renewed based on a spring-swinging column model.First,in accordance with the concept of structural transformation,the frame repeating unit was introduced to solve the floor lateral stiffness,and the critical stiffness ratio coefficient was adopted to solve the floor load stiffness.Then,the floor lateral stiffness and the floor load stiffness were assembled as a whole,and the second-order calculation for solving the overall stability critical bearing capacity of steel frames was transformed into a first-order problem to determine the overall lateral stiffness of frames.Finally,the activation degree of the floor stiffness was considered based on the method of axial force weighted average,and the direct calculation of the critical bearing capacity of steel frames was achieved.The method proposed can judge the weak layer of frame structures,due to its advantages of quantitatively calculating the degree of mutual support between floors,and improving the unreasonable design caused by the standard calculation length method,where the two support functions were not considered・The results of calculation examples show that the method has good precision and accuracy,and can be used for engineering design.