考虑除尘器箱体墙板-立柱协同受力时立柱在横向荷载作用下的内力计算
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摘要
大气除尘装备箱体围护结构形式和荷载情况十分复杂,目前尚无关于除尘器箱体立柱在横向荷载作用下其内力分布的精确计算方法。该文采用理论推导与有限元计算相结合的方法对除尘器箱体立柱在墙板直接受横向荷载作用时的内力与强度计算方法进行研究。在考虑墙板所受横向荷载向立柱传递时,将墙板视作由上、下相邻加劲肋和左、右两侧立柱围成的四边简支板,加劲肋处传递集中力,加劲肋间传递非均匀分布荷载。将立柱作为多跨连续弹性梁,采用力矩分配法编写程序计算其最大弯矩和剪力值。根据除尘器箱体立柱的跨数、每跨立柱范围内对应墙板区格数目以及墙板区格宽高比,编制了立柱最大弯矩计算表格。考虑墙板与立柱的协同受力作用,以有效宽度范围内的墙板与立柱组成组合截面共同抗弯,修正立柱正截面强度计算方法。研究结果表明:在墙板与立柱组合结构体系中,随着墙板壁厚增大或墙板宽度减小,墙板的抗弯贡献提高;随着立柱截面惯性矩增大或立柱横向支撑间距减小,墙板的抗弯贡献降低。根据对工程常用几何构造的除尘器箱体结构计算统计,偏于安全地提出了立柱截面模量统一放大系数。相比于传统工程简化内力计算方法,工程设计人员可以利用该文提出的方法方便、准确地计算立柱内力最大截面的正应力和剪应力,从而设计出安全经济的立柱截面。
The structure and loading conditions of the enclosed structure of precipitator casings are highly complicated. Currently, there is no accurate method to calculate the internal force distribution in the columns of precipitator casings under transverse loading. In this paper, we investigate a method to calculate both the internal force and strength of precipitator casing columns when a transverse load is directly applied to the wallboard. Both theoretical and finite element analyses are conducted. To effectively study the transferring mechanism of the transverse load, a block of wallboard is regarded as an independent plate with simply supported edges separated by upper and lower neighboring stiffeners and columns on the left and right sides. Concentrated forces are transferred at the location of each stiffener, and nonuniformly distributed loads are transferred between the stiffeners. The column is regarded as an elastic multi-span continuous beam and the maximum bending moment and shear force are evaluated using the moment distribution method. Calculation tables for the maximum bending moment of various columns are determined based on the number of column spans, the number of wallboard blocks in the range of the corresponding column span and the aspect ratio of the wallboard block. Considering the load bearing interaction between the column and wallboard, a composite section is proposed to revise the strength evaluation method for the normal cross sections of columns. A composite section consists of an H-shaped column and the wallboard within the effective width. The results show that for a composite structure composed of a wallboard and a column, the contribution of the wallboard to the bending resistance increases as the wallboard thickness increases or as the wallboard width decreases. The contribution of the column to the bending resistance increases as the inertial moment of the column section increases or as the column span decreases. Based on the statistics of the computation results for the precipitator casings with usual geometries in engineering practice, a unified magnification factor for the column section modulus is proposed on the safe side. Compared to the conventional simplified internal force calculation methods, the proposed calculation method can more conveniently and accurately evaluate the maximum normal and shear stresses for a column section to assist the design of safe and economical column sections under transverse loading.
The structure and loading conditions of the enclosed structure of precipitator casings are highly complicated. Currently, there is no accurate method to calculate the internal force distribution in the columns of precipitator casings under transverse loading. In this paper, we investigate a method to calculate both the internal force and strength of precipitator casing columns when a transverse load is directly applied to the wallboard. Both theoretical and finite element analyses are conducted. To effectively study the transferring mechanism of the transverse load, a block of wallboard is regarded as an independent plate with simply supported edges separated by upper and lower neighboring stiffeners and columns on the left and right sides. Concentrated forces are transferred at the location of each stiffener, and nonuniformly distributed loads are transferred between the stiffeners. The column is regarded as an elastic multi-span continuous beam and the maximum bending moment and shear force are evaluated using the moment distribution method. Calculation tables for the maximum bending moment of various columns are determined based on the number of column spans, the number of wallboard blocks in the range of the corresponding column span and the aspect ratio of the wallboard block. Considering the load bearing interaction between the column and wallboard, a composite section is proposed to revise the strength evaluation method for the normal cross sections of columns. A composite section consists of an H-shaped column and the wallboard within the effective width. The results show that for a composite structure composed of a wallboard and a column, the contribution of the wallboard to the bending resistance increases as the wallboard thickness increases or as the wallboard width decreases. The contribution of the column to the bending resistance increases as the inertial moment of the column section increases or as the column span decreases. Based on the statistics of the computation results for the precipitator casings with usual geometries in engineering practice, a unified magnification factor for the column section modulus is proposed on the safe side. Compared to the conventional simplified internal force calculation methods, the proposed calculation method can more conveniently and accurately evaluate the maximum normal and shear stresses for a column section to assist the design of safe and economical column sections under transverse loading.
引文
[1]Rane M A,Patil G V,Thokal G,et al.Design and optimization of electrostatic precipitator using finite element analysis tool[J].International Journal of Mechanical Engineering&Technology,2014,5(1):90―97.
[2]王登峰,王元清,石永久,等.电除尘器壳体墙板-立柱结构体系缺陷敏感性研究[J].工程力学,2012,29(5):78―85.Wang Dengfeng,Wang Yuanqing,Shi Yongjiu,et al.Imperfection sensitivity of wall-column structural system in electrostatic precipitator casing[J].Engineering Mechanics,2012,29(5):78―85.(in Chinese)
[3]丁晓红,马曼.基于自适应成长法的大型电除尘器烟箱优化设计方法[J].中国机械工程,2013,24(18):2431―2436.Ding Xiaohong,Ma Man.Optimum design method for large-scale inlet&outlet of electrostatic precipitator based on adaptive growth method[J].China Mechanical Engineering,2013,24(18):2431―2436.(in Chinese)
[4]Wang X,Rammerstorfer F G.Determination of effective breadth and effective width of stiffened plates by finite stripe analyses[J].Thin-Walled Structures,1996,26(4):261―286.
[5]Katsikadelis J T,Sapountzakis E.A realistic estimation of the effective breadth of ribbed plates[J].International Journal of Solids and Structures,2002,39(4):789―799.
[6]Paulo R M F,Teixeira-Dias F,Valente R A F.Numerical simulation of aluminium stiffened panels subjected to axial compression:Sensitivity analyses to initial geometrical imperfections and material properties[J].Thin-Walled Structures,2013,62(1):65―74.
[7]Shanmugam N E,Zhu D Q,Choo Y S,et al.Experimental studies on stiffened plates under in-plane load and lateral pressure[J].Thin-Walled Structures,2014,80(1):22―31.
[8]Wang Dengfeng,Yu Yongfu,Pan Licheng,et al.Study of load bearing capacity of profiled steel sheet wall subjected to combined bending and vertical compression in electrostatic precipitator[J].Open Mechanical Engineering Journal,2014,8(1):326―331.
[9]杨嘉胤,童根树,张磊.竖向闭口加劲钢板剪力墙在非均匀压力下的弹性稳定性研究[J].工程力学,2015,32(11):132―139.Yang Jiayin,Tong Genshu,Zhang Lei.Research of elastic buckling of steel shear walls stiffened by vertical tubes under nonuniform compression[J].Engineering Mechanics,2015,32(11):132―139.(in Chinese)
[10]Wrzesien A M,Lim J B P,Xu Y,et al.Effect of stressed skin action on the behavior of cold-formed steel portal frames[J].Engineering Structures,2015,105:123―136.
[11]Nagy Z S,Pop A,Mois I,et al.Stressed skin effect on the elastic buckling of pitched roof portal frames[C].Amsterdam:Published by Elsevier Ltd,2016:227―244.
[12]王登峰,贾文文,王元清.初始缺陷对除尘器壳体立柱轴压稳定性的影响[J].中南大学学报(自然科学版),2016,47(8):2810―2819.Wang Dengfeng,Jia Wenwen,Wang Yuanqing.Influence of initial imperfection on stability of axially compressed column in electrostatic precipitator casing[J].Journal of Central South University(Science and Technology),2016,47(8):2810―2819.(in Chinese)
[13]潘立程,邢凯丽,钱海峰,等.考虑受力蒙皮作用的除尘器壳体墙板的承载性能[J].工程科学学报,2016,38(9):1335―1342.Pan Licheng,Xing Kaili,Qian Haifeng,et al.Bearing performance of wallboards in an electrostatic precipitator casing in consideration of stressed skin effect[J].Chinese Journal of Engineering,2016,38(9):1335―1342.(in Chinese)
[14]黄克智.板壳理论[M].北京:清华大学出版社,1987:74―77.Huang Kezhi.Theory of plate and shells[M].Beijing:Tsinghua University Press,1987:74―77.(in Chinese)
[15]钱海峰,王登峰.除尘器箱体立柱在横向荷载作用下的剪力计算[C].北京:工业建筑杂志社,2018:677―684.Qian Haifeng,Wang Dengfeng.Shear evaluation of column in electrostatic precipitator casing under transversal load[C].Beijing:Industrial Construction Magazine Agency,2018:677―684.(in Chinese)
[2]王登峰,王元清,石永久,等.电除尘器壳体墙板-立柱结构体系缺陷敏感性研究[J].工程力学,2012,29(5):78―85.Wang Dengfeng,Wang Yuanqing,Shi Yongjiu,et al.Imperfection sensitivity of wall-column structural system in electrostatic precipitator casing[J].Engineering Mechanics,2012,29(5):78―85.(in Chinese)
[3]丁晓红,马曼.基于自适应成长法的大型电除尘器烟箱优化设计方法[J].中国机械工程,2013,24(18):2431―2436.Ding Xiaohong,Ma Man.Optimum design method for large-scale inlet&outlet of electrostatic precipitator based on adaptive growth method[J].China Mechanical Engineering,2013,24(18):2431―2436.(in Chinese)
[4]Wang X,Rammerstorfer F G.Determination of effective breadth and effective width of stiffened plates by finite stripe analyses[J].Thin-Walled Structures,1996,26(4):261―286.
[5]Katsikadelis J T,Sapountzakis E.A realistic estimation of the effective breadth of ribbed plates[J].International Journal of Solids and Structures,2002,39(4):789―799.
[6]Paulo R M F,Teixeira-Dias F,Valente R A F.Numerical simulation of aluminium stiffened panels subjected to axial compression:Sensitivity analyses to initial geometrical imperfections and material properties[J].Thin-Walled Structures,2013,62(1):65―74.
[7]Shanmugam N E,Zhu D Q,Choo Y S,et al.Experimental studies on stiffened plates under in-plane load and lateral pressure[J].Thin-Walled Structures,2014,80(1):22―31.
[8]Wang Dengfeng,Yu Yongfu,Pan Licheng,et al.Study of load bearing capacity of profiled steel sheet wall subjected to combined bending and vertical compression in electrostatic precipitator[J].Open Mechanical Engineering Journal,2014,8(1):326―331.
[9]杨嘉胤,童根树,张磊.竖向闭口加劲钢板剪力墙在非均匀压力下的弹性稳定性研究[J].工程力学,2015,32(11):132―139.Yang Jiayin,Tong Genshu,Zhang Lei.Research of elastic buckling of steel shear walls stiffened by vertical tubes under nonuniform compression[J].Engineering Mechanics,2015,32(11):132―139.(in Chinese)
[10]Wrzesien A M,Lim J B P,Xu Y,et al.Effect of stressed skin action on the behavior of cold-formed steel portal frames[J].Engineering Structures,2015,105:123―136.
[11]Nagy Z S,Pop A,Mois I,et al.Stressed skin effect on the elastic buckling of pitched roof portal frames[C].Amsterdam:Published by Elsevier Ltd,2016:227―244.
[12]王登峰,贾文文,王元清.初始缺陷对除尘器壳体立柱轴压稳定性的影响[J].中南大学学报(自然科学版),2016,47(8):2810―2819.Wang Dengfeng,Jia Wenwen,Wang Yuanqing.Influence of initial imperfection on stability of axially compressed column in electrostatic precipitator casing[J].Journal of Central South University(Science and Technology),2016,47(8):2810―2819.(in Chinese)
[13]潘立程,邢凯丽,钱海峰,等.考虑受力蒙皮作用的除尘器壳体墙板的承载性能[J].工程科学学报,2016,38(9):1335―1342.Pan Licheng,Xing Kaili,Qian Haifeng,et al.Bearing performance of wallboards in an electrostatic precipitator casing in consideration of stressed skin effect[J].Chinese Journal of Engineering,2016,38(9):1335―1342.(in Chinese)
[14]黄克智.板壳理论[M].北京:清华大学出版社,1987:74―77.Huang Kezhi.Theory of plate and shells[M].Beijing:Tsinghua University Press,1987:74―77.(in Chinese)
[15]钱海峰,王登峰.除尘器箱体立柱在横向荷载作用下的剪力计算[C].北京:工业建筑杂志社,2018:677―684.Qian Haifeng,Wang Dengfeng.Shear evaluation of column in electrostatic precipitator casing under transversal load[C].Beijing:Industrial Construction Magazine Agency,2018:677―684.(in Chinese)