箱形截面压弯杆弯扭屈曲承载力  

Flexural-Torsional Capacity of Beam-Column with Box Section

作　　者：陈海啸[1] 童根树[2] Haixiao Chen;Genshu Tong(Zhejiang Prov.Institute of Architectural Design and Research,Hangzhou 310006,China;Institute of High Performaced Structure,Zhejiang University,Hangzhou 310058,China)

机构地区：[1]浙江省建筑设计研究院,杭州310006 [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9期30-55,共26页Steel Construction（Chinese & English）

摘　　要：对箱形截面压弯杆弯扭屈曲承载力验算公式进行了理论研究,主要工作如下: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)对箱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,并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,得到了箱形截面压弯杆的弯扭屈曲计算公式,画出了一系列曲线,提出了拟合公式。可知:在长细比较小时,曲线接近强度相关曲线、随长细比增大,曲线接近弹性屈曲相关公式;继续增大长细比,则曲线超越弹性屈曲相关公式。对比研究表明,现行GB 50017—2017《钢结构设计标准》中的平面内和平面外稳定计算公式共同控制着杆件的承载力,在现行平面外稳定公式看似偏不安全的地方,由平面内稳定公式保证杆件安全。A theoretical study was carried out for the flexural-torsional buckling capacity of beam-columns with box-section.The main works and developments were as follows:1)Comparisons were carried out between the formulae used in the codes of GB50017-2017,AISC LRFD2016,Eurocode3part1-1and the formulae derived in the flexural-torsional theory,possible improvements are pointed out.2)As the first step of the development,plastic 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.3)Second-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.4)Based 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.5)Introducing 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 interac

关 键 词：弯扭屈曲 压弯杆 箱形截面 二阶效应 

分 类 号：TU391[建筑科学—结构工程]