偏载作用下薄壁箱梁空间整体效应的综合分析  

Comprehensive analysis on spatial integral effect of thin-walled box girders under eccentric load

作　　者：张元海[1] 马云亮 刘泽翔 Zhang Yuanhai;Ma Yunliang;Liu Zexiang(Lanzhou Jiaotong University,Lanzhou 730070,China)

机构地区：[1]兰州交通大学,兰州730070

出　　处：《土木工程学报》2024年第4期48-58,共11页China Civil Engineering Journal

基　　金：国家自然科学基金(51968040);兰州交通大学基础研究拔尖人才计划项目(2022JC17)。

摘　　要：为了研究斜腹板箱梁在竖向偏心荷载作用下的受力性能,在合理构造各翘曲位移函数的基础上,用能量变分法建立全面反映竖向弯曲变形以及剪力滞、约束扭转、畸变等翘曲变形的控制微分方程,通过对既有文献中的模型梁进行计算分析,明确剪力滞、约束扭转及畸变翘曲应力在竖向弯曲应力中的占比情况,并揭示各翘曲广义内力的分布规律。结果表明:按文章解析法求得的模型梁应力理论值与实测值吻合良好,从而验证文章方法的合理性;在偏载作用下箱梁的约束扭转微分方程与畸变微分方程是相互耦联的,这在已有文献中往往被忽略;在剪力滞、约束扭转及畸变翘曲应力中,畸变翘曲应力占据主导地位,剪力滞和约束扭转翘曲应力相对较小,但仍不可忽略,在控制截面上因各种翘曲变形引起的应力放大系数达到1.362;偏心集中荷载引起的各翘曲广义内力均具有快速衰减的分布规律,剪力滞和约束扭转广义内力分布范围很小,而畸变广义内力分布范围广阔。建议在桥梁设计规范相关条文及实际箱梁桥设计中,对畸变效应给予充分重视。In order to study the mechanical behavior of box girders with inclined web under vertical eccentric load,warping displacement functions were first built,then the governed differential equations that comprehensively reflect the vertical bending deformation and the warping deformation of shear lag,restrained torsion and distortion were established by the energy variation method.By calculating and analyzing the model girder in the existing documents,the proportion of the warping stress due to shear lag,restrained torsion and distortion in the vertical bending stress was determined,and the distribution law of each generalized internal force was revealed.The results show that the theoretical value of the stress of the model girder obtained by the analytic method in this paper is in a good agreement with the measured value,which verifies the rationality of the proposed method.The differential equation for restrained torsion and that for distortion of the box girder are coupled under the action of eccentric load,which was often ignored in the existing literature.Among the warping stresses due to shear lag,restrained torsion and distortion,the distortion warping stress dominates.The warping stress due to shear lag and restrained torsion is relatively small but cannot be ignored.The stress amplification factor caused by the warping deformation reaches 1.362 at the control section.The generalized internal force due to warping under eccentric concentrate load has a distribution law of rapid attenuation.The distribution range of the generalized internal force due to shear lag and restrained torsion is very small,while that due to distortion is broad.It is suggested that full attention should be paid to the distortion effect in the relevant provisions of the bridge design code and in the actual design of box girder bridges.

关 键 词：薄壁箱梁 畸变 剪力滞效应 约束扭转 翘曲应力 

分 类 号：U448.213[建筑科学—桥梁与隧道工程]