负载下焊接加固钢结构压弯构件受力性能的影响因素分析
Influence Factor Analysis of Mechanical Behavior of Compression-bending Member of Steel Structure Strengthened by Welding Under Load

为研究负载下焊接加固钢结构压弯构件的受力性能，采用考虑焊接热影响的有限元分析方法，对不同初始负载、偏心距、长细比及焊接热输入等级等影响因素进行分析。完成了包括未加固压弯钢柱及加固压弯钢柱共72个构件的受力全过程模拟分析，获得了各因素影响规律，并验证了考虑二阶效应的新的名义应力比计算公式。结果表明：未加固构件的初始负载水平可通过二阶式反映；初始几何缺陷模式及大小影响失稳破坏方向及焊接残余变形大小；影响加固构件极限承载力的主要因素依次为偏心距、长细比、焊接热输入、初始应力比；影响焊接残余变形的主要因素依次为焊接热输入、初始应力比、长细比；为新编《钢结构加固设计规范》关于负载下焊接加固压弯构件设计计算方法提供了参考和依据。
In order to investigate the mechanical behavior of compression？？bending member of steel structure strengthened by welding under load, the finite element analysis method considering welding heat effect was used to analyze the influence factors, such as initial load, eccentric distance, slenderness ratio, class of weld heat input. The whole loading process simulation analyses of 72 members of unstrengthened and strengthened bending steel columns were carried out, and the influence rules of the factors were acquired. The new second？？order design formula of nominal stress was verified as well. The results show that initial load level can be evaluated by the second？？order formula. The mode and amount of initial geometrical imperfections effect the direction of buckling and magnitude of residual deformation. Besides, the factor order of influencing on the ultimate capacity of strengthened specimen is eccentricity, slenderness ratio, welding heat input and initial stress. While concerning the welding residual deformation, the factor order turn out to be welding heat input, initial stress and slenderness ratio. The conclusion can provide reference and basis to establish the design calculation method of compression？？bending member strengthened by welding under load in ？？Code for Design of Strengthening Steel Structure