箱梁剪力滞效应分析的有效宽度法对荷载类型适应性研究  

Study on Adaptability of Effective Width Method for Analyzing Shear Lag Effect of Box Beam to Load Types

作　　者：李晶 张元海[1] LI Jing;ZHANG Yuanhai(School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China)

机构地区：[1]兰州交通大学土木工程学院,兰州730070

出　　处：《铁道标准设计》2021年第9期121-126,共6页Railway Standard Design

基　　金：国家自然科学基金项目(51968040)。

摘　　要：针对现行桥梁设计规范中箱梁有效宽度的应用未区分荷载类型的情况,通过有效宽度法计算集中荷载和均布荷载下的应力精度,分析有效宽度法对荷载类型的适应性。根据能量变分法建立关于剪力滞附加挠度的控制微分方程和边界条件,分别给出简支箱梁在集中荷载和均布荷载作用下的剪力滞效应计算公式。选取一简支箱梁为算例,按考虑剪力滞效应的解析法计算集中荷载和均布荷载下的应力,并用ANSYS数值解验证应力结果的正确性。将有效宽度法计算的应力与解析解进行对比,结果表明:有效宽度法对均布荷载的适应性较强,对集中荷载的适应性不强。为提高有效宽度法对集中荷载的适应性,针对集中荷载作用于跨中的情况,对公路规范的中部梁段有效宽度提出修正系数为0.92,对铁路规范的跨中有效宽度提出修正系数为0.95,结果表明,修正后的有效宽度法对集中荷载有良好的适应性。In view of the situation that the applicability of effective width of box beam in the current bridge design code does not distinguish load types,the effective width method is used to calculate the stress accuracy under concentrated load and uniform load,and analyze the applicability of the effective width method to load types.The governing differential equation and boundary conditions about shear lag additional deflection are established by using energy variational method.The formulas to calculate shear lag effect of simply supported box beam under concentrated load and uniformly distributed load are provided.A simply supported box beam is selected as the example,and the stress under concentrated load and uniformly distributed load are calculated according to the present analytic method considering shear lag effect.The correctness of the stress results is verified by ANSYS numerical solutions.The stress values calculated with the effective width method are compared with the analytic solution.The results show that the effective width method has strong applicability to uniformly distributed load and it is not to concentrated load.In order to improve the applicability of the effective width method to concentrated load,a correction factor 0.92 for the effective width of the middle segment of the beam is proposed in the highway code and a correction factor 0.95 of the middle span is proposed in the railway code under the situation where the concentrated load acts on the middle span.The results show that the modified effective width method has good applicability to concentrated load.

关 键 词：箱梁 有效宽度法 剪力滞效应 荷载类型 桥梁设计规范 

分 类 号：U448.213[建筑科学—桥梁与隧道工程] U441.5[交通运输工程—道路与铁道工程]