除尘器壳体双肢组合截面立柱轴压稳定性研究

除尘器壳体围护结构中的立柱因需要支承顶部较宽截面的箱形梁以及承担较大的轴力而设计成双肢H型钢组合截面。利用非线性有限元方法，研究此双肢组合截面柱在考虑初始缺陷情况下承受轴向压力时的稳定性。研究表明，立柱轧制、墙板与立柱焊接产生的残余应力会小幅降低立柱稳定承载力。立柱的失稳形式为柱顶跨段内前翼缘与前腹板组成T形截面整体弯扭失稳与腹板局部失稳同时发生的相关失稳。墙板与两肢间连接墙板作为蒙皮板，为立柱承担部分荷载并约束其侧向变形。连接墙板越靠近前翼缘，立柱的稳定性越好。连接墙板宽度、墙板宽度、墙板角钢加劲肋刚度和节点连接板厚度等因素对立柱稳定性影响较小。仅邻近立柱的墙板和连接墙板增厚可对立柱稳定性有增强作用，远离立柱的墙板壁厚影响较小。立柱稳定系数与H型钢柱翼缘宽厚比的关系不是单调的；立柱绕弱轴弯曲长细比、腹板高厚比的增大会降低立柱稳定性。基于大量非线性有限元计算结果，提出了除尘器壳体中双肢组合截面轴心受压柱稳定承载力的计算建议。

STABILITY OF AXIALLY COMPRESSED COLUMNS COMPOSED OF DOUBLE LIMBS IN PRECIPITATOR CASING

A cross-section of the column in the enclosure structure of electrostatic precipitator casing is composed of double H-shaped limbs as it needs to support the top beam with a wide box section and bear large axial compression.The nonlinear finite element method was used to investigate the stability of the composite section column subjected to axial compression in consideration of the initial imperfections.The research results showed that the residual stresses caused by column rolling and the welding between wallboard and column had a slight adverse influence on the buckling capacity of the column.The column presented the interactive buckling in the top span,that is,the overall flexural-torsional buckling occurred on the T-shaped section composed of the front flange,and the front half web and the local buckling occurred simultaneously on the web.Wallboard and the connecting wallboard as stressed skin plates,shared part of the load and restrained the lateral deformation of the column.The stability of the column increased when the connecting wallboard was close to its front flange.Factors such as the connecting wallboard width,the wallboard width,the stiffness of the angle stiffener and the thickness of the joint plate slightly influenced the stability of the column.When the thickness of neighboring wallboard and neighboring connecting wallboard increased,the stability of the column increased.However,the thickness of the wallboard far from the column had little influence.The buckling factor of the column did not change monotonously with the increase of the width to thickness ratio of the flange.However,it decreased with the increase in the flexural slenderness ratio of the H-shaped limb round its weak axis and the height to thickness ratio of the web.Based on a large number of the nonlinear finite element computation results,an evaluation method was proposed for the buckling bearing capacity of the column composed of double limbs in precipitator casing under axial compression.