半刚接钢框架稳定分析中柱的计算长度取值研究

The Research of Effective Length for Columns in Semi-rigid Steel Frames Stability Analysis

根据钢框架稳定设计中柱子计算长度的概念 ,研究了钢框架中梁柱节点半刚接柱的计算长度系数取值问题 ,采用螺旋弹簧模拟梁柱节点连接的半刚性 ,考虑了梁柱间的相对转角关系 ,通过引入梁柱线刚度比修正系数的计算方法 ,推导了有侧移和无侧移半刚接钢框架柱计算长度系数的修正公式 .研究结果表明 :受节点半刚性影响 ,半刚接钢框架柱的计算长度系数比按刚接考虑的计算长度系数增大 ,增大范围约在 6 %～ 9%左右 ;框架柱除底层外 ,其上下两端与横梁的连接基本是半刚接的形式 ,按横梁有侧移考虑 ,柱的计算长度系数比柱两端按照刚性节点计算出的计算长度系数值增大了 9%左右 .由此可见在钢框架的稳定分析和设计中 。

According to the column effective length concept of steel frames stability design, the effective length factor of columns in semi-rigid steel frames is studied. The modified factor formulas, which are applicable to the braced and unbraced steel frames, are derived by the joint relative rotation under consideration and by adopting the modified stiffness factor. The semi-rigid connection is stimulated by a rotational spring. It shows that, compared with the rigid connection, the effective length factors increase by 6%～9% due to the effect of the semi-rigid. The columns of the frames except the bottom are semirigid connected with the beams in the two ends. The factors of the columns increase by 9% compared with the rigid connection. Thereby the influence of the semi-rigid connection should be taken into account in the stability analysis and design of the steel frames.