H形截面压弯杆弯扭屈曲承载力  

Flexural-Torsional Buckling Capacity of Beam-Columns with H-Section

作　　者：周佳[1] 童根树[2] Jia Zhou;Genshu Tong(China Southwest Architectural Design&Research Institute Corp.,Chengdu 610041,China;Institute of High-Performace Structures,Zhejiang University,Hangzhou 310058,China)

机构地区：[1]中国建筑西南设计研究院有限公司,成都610041 [2]浙江大学高性能结构研究所,杭州310058

出　　处：《钢结构（中英文）》2022年第10期1-23,共23页Steel Construction（Chinese & English）

摘　　要：对H形截面压弯杆弯扭屈曲承载力验算公式进行了理论研究,主要工作为:1对我国、欧洲和美国的钢结构设计规范中H形截面压弯杆平面外稳定验算公式进行了比较,指出了改进的可能性;2对有初始弯曲和扭转压弯杆的弹性弯扭变形进行了二阶分析,在引入初始弯曲和初始扭转的特定关系后,得到了二阶效应放大后的弯曲、扭转、弯矩和双力矩的简单的解析表达式;3对H形截面绕强轴和绕弱轴的单向压弯塑性铰状态的强度公式分别进行了单一表达式拟合;对给定压力时双向弯矩作用下的塑性铰状态的双向弯矩相关关系进行了计算,提出了精度良好、略偏安全的公式;将提出的公式进行改造,使之能够考虑双力矩的影响;4参照压弯杆平面内稳定验算公式的推导方法,利用已知的绕弱轴弯曲屈曲的柱子稳定系数公式,反推获得了压杆绕弱轴弯曲屈曲的等效初始弯曲,该等效初始弯曲综合考虑了残余应力、初始弯曲和塑性开展过程带来的额外挠度增量;5引入该等效初始弯曲。采用平面内二阶分析获得的二阶弯矩,平面外二阶弯矩和二阶双力矩等,代入双向压弯强度计算式,得到压弯杆弯扭屈曲承载力的上限解。为了获得更为接近实际的承载力相关关系,对弹性分析得到的平面内二阶弯矩和平面外二阶弯矩以及双力矩进行弹塑性放大,得到了H形截面压弯杆的弯扭屈曲计算公式,画出了一系列曲线,在长细比小时,曲线接近强度相关曲线,长细比大时,曲线接近弹性屈曲相关公式。结果表明:现行GB 50017—2017《钢结构设计标准》中的平面外稳定计算公式是偏于安全的。同时借用强度相关关系和屈曲相关关系的插值,给出了比较复杂的拟合公式。A theoretical study is carried out for the flexural-torsional buckling capacity of beam-columns with H-section.The main works and developments are as follows:1Comparisons are carried out between the formulae used in the codes of GB 50017-2017,AISC LRFD 2016,Eurocode 3 part 1-1 and the formulae derived in the flexural-torsional theory,possible improvements are pointed out.2Second-order analysis is carried out for the beam-columns with initial deflection and initial twisting,after introducing a specific relation between the initial deflection and initial twisting,simple expressions are obtained for the lateral displacement,twisting angle,lateral bending moments and bi-moments.3Plastic interactive relations are obtained for the axial force and bending moments about the strong axis and about the weak axis respectively.Fitting curves with good accuracy are provided for interaction equations of axial force-bending moments about the strong axis and about the weak axis.For the general cases of axial force and biaxial bending moments,exact analysis is carried out for the state of spatial plastic hinges and an approximate interactive equation for biaxial bending under a given axial force is also proposed.The effect of bi-moment is incorporated into the proposed equation.4Based on the well-accepted and codified column strength reduction factor,the equivalent initial out-of-plane deflections are obtained by taking the buckling strength of the column about the weak axis as a plastic hinge state under the axial force and the amplified bending moment due to the second order effect and initial deflection,this equivalent initial deflection includes the effect of residual stress,initial deflection and the additional deflection increment due to plasticity development.5Introducing this equivalent initial deflection into the second-order bending moment about the weak axis and into the bi-moment,together with the second-order in-plane bending moment,they are substituted into the spatial interactive equation of the axial force and biax

关 键 词：弯扭屈曲 压弯杆 H形截面 二阶效应 

分 类 号：TU312[建筑科学—结构工程]