半刚接钢框架柱的稳定分析方法

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性连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要大,约增大2%～6%;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刚性节点计算出的计算长度系数值增大了4%左右。由此可见,在钢框架的稳定分析和设计中,应考虑由于梁柱节点采用半刚接的连接形式,对框架柱的稳定性产生的不利影响。

THE STABILITY ANALYSIS OF COLUMNS FOR STEEL FRAMES WITH SEMI-RIGID CONNECTION

This paper is concerned with the effective length factor of columns in semi-rigid steel frames on the base of the effective length concept in stabili t y design of steel frames. The modified effective length factor formulas of unbra ced and braced steel frames are derived by joint relative rotation and the modif ied factor of the beam-to-column linear stiffness ratio under consideration. T he semi-rigid connection is stimulated by a rotational spring. It is shown that t h e effective length factors increase by 2%～6% due to the effect of the flexibili t y of the connections. The columns of the frames except the bottom are semi-rigi d connected with the beams in the two ends and the factors of the columns increas e by 4% compared with the rigid connection. Thus, it is concluded that the effec t of the semi-rigid connection should be taken into account in the stability an alysis and design of the steel frames. [JP3]