有侧移半刚性连接钢框架柱计算长度的研究

基于钢框架稳定设计中柱计算长度的概念,本文采用三柱框架结构计算模型,通过考虑连接的非线性弯矩-转角关系,建立梁柱的有侧移半刚性连接转角位移方程,将横梁对柱子的约束弯矩按柱子的线刚度之比分配给柱;然后通过引入梁柱线刚度比修正系数的计算方法,推导了有侧移半刚性钢框架柱计算长度系数方程式,并研究了在梁-柱半刚性连接下柱的计算长度系数取值问题.本文得到的半刚性连接的柱计算长度系数公式与《钢结构设计规范》(GB50017-2003)中的刚性钢框架柱计算长度系数形式相同.算例结果表明:考虑半刚性影响后,柱的有效长度系数增大7%以上,此类钢框架计算时应考虑梁柱节点半刚性的影响.本文计算方法简捷方便,便于工程实际应用.

Analysis on effective length of column in semi-rigid jointed steel frames with lateral displacements

Based on the concept of effective column length in stability analysis of steel frames,the slope-deflection equation of the for with semi-rigid connections,which considered the effects of the nonlinear moment rotation characteristics of beam-column connections,is established by using the three column sub assemblage model,and the restrained moments from beam to column in the semi-rigid connection is distributed according to the ratios of column linear stiffness.The equation of effective column length factor in semi-rigid connections of un-braced steel frames are derived by adopting the modified factor of linear stiffness ratio,and the effective length factors of columns in semi-rigid steel frames are analyzed.The expression of the formula is similar to the formula given in the Code for Design of Steel Structures(GB50017-2003).The calculation results show that the length factor of columns increase 7% above under considered the semi-rigid factor influence,and these influences need to be considered in stability analysis of the steel frames.The calculation method proposed in this paper is simple and convenient,and easy to use for engineering design.