（国防科大指挥军官基础教育学院，长沙 410072）

［摘要］推导了竖向力对框架的抗侧刚度影响系数α，并分别对计算侧移框架二阶效应的P-Δ法、二阶弹性分析法和双二阶效应法的计算长

度系数进行修正。通过与《钢结构设计规范》(GB50017—2003)比较得知，双二阶效应法计算长度系数取值比规范安全，修正后的P-Δ法和二阶弹性分析法与规范最为接近，而二阶弹性分析法和P-Δ法在梁柱线刚度比K₁大于1时偏于不安全。

［关键词］抗侧刚度影响系数；计算长度系数；二阶效应；梁柱线刚度比

Modified effective length coefficient of sway-frame considering vertical loads

Hu Qigao, Kong Weixue,Duan Jinxi,Xie Jianjun

（Military Basic Education College, National University of Defense Technology, Changsha 410072, China）

Abstract:The lateral stiffness factor α is deduced and used to modify the effective length coefficient which calculates sway frame′s second-order effect such as the P-Δmethod, second-order elastic analysis method and double second-order effect method. Through comparing with the  code for design of steel structure, it is showed that the double second-order effect method is beyond safe, the modified P-Δmethod and modified second-order elastic analysis method approximate to code, and the P-Δmethod and second-order elastic analysis method is not safe when beam-column′s linear stiffness ratio K₁ beyond 1.

Keywords:lateral stiffness factor; effective length coefficient; second-order effect; beamcolumn′s linear stiffness ratio