单箱双室变截面波形钢腹板组合梁剪应力分析

Analysis of shear stress of single-box double-cell variable cross-section composite box beams with corrugated steel web

为了研究单箱双室变截面波形钢腹板组合箱梁(CBBCSW)的剪应力分布规律,分析了单箱双室变截面CBBCSW的顶底板与波形钢腹板(CSW)的承剪问题。基于微元体平衡和切应力互等定理推导了变截面CSW的剪应力计算公式,并与等截面CSW剪应力计算公式进行了对比。对各项剪应力的性质展开了研究,针对变截面CBBCSW的顶底板和参与承剪机理进行了分析,提出了底板承剪比例计算公式。以室内模型试验梁和一座单箱双室变截面CBBCSW为例,采用ANSYS有限元软件分别建立了试验梁与实桥的有限元模型,研究了不同约束体系下,剪应力在CSW上的分布以及顶底板与CSW参与承剪的规律。对比不同荷载情况下,有限元计算结果与理论公式计算结果的差异,分析不同荷载工况对顶底板与CSW参与承剪的影响。此外,分析了横隔板对单箱多室CBBCSW剪力分配的影响。研究结果表明:所提公式的理论结果与试验实测结果和有限元结果吻合较好,且底板参与承剪的比例不可忽视;变截面引起的“附加剪应力”是影响剪力传递的直接原因,弯矩的大小会直接影响底板参与承剪的比例;对称荷载下中腹板与边腹板的剪力分布几乎相同,而横隔板会改变CSW上剪力分配,靠近横隔板处的部位剪应力分布更均匀。研究结果可以为实际工程中变截面CSW的剪应力和承剪比的分析提供参考依据。

To study the shear stress distribution of single-box double-cell variable cross-section composite box beams with corrugated steel web(CBBCSW),the problem that the top,bottom and corrugated steel web(CSW)of the single-box double-cell variable cross-section CBBCSW participate in shear was analyzed.The formula for calculating shear stress of CSW with variable cross section was derived by using the equilibrium of infinitesimal element and the reciprocal theorem of shear stress,and compared with shear stress calculation formula of CSW with uniform cross section.The properties of various shear stress were studied,and the top and bottom plates of variable cross-section CBBCSW and the mechanism of participating in shear bearing were analyzed.The formula for calculating the bearing-shear ratio of the bottom plate was proposed.Taking the model test beam and a singlebox double-cell variable cross-section CBBCSW as examples,the finite element(FE)models of the test beam and the bridge model were developed by using ANSYS.The distribution of shear stress on CSW under different restraint systems and the law of top,bottom and CSW participating in shear were studied.The difference between the finite element calculation results and the theoretical formula calculation results under different load conditions was compared.The influence of different load conditions on the participation of the top,bottom and CSW in shear was analyzed.In addition,the effect of the diaphragm on the distribution of shear force was analyzed.The results show that the theoretical results of the proposed formula are in good agreement with the test results and FE results.The proportion of the bottom plates participating in the shear bearing cannot be ignored.The“additional shear stress”caused by variable cross-section is the direct reason that affects shear force transmission.The size of bending moment will directly affect the proportion of bottom plate participating in shear bearing.Under symmetrical load,the shear force distribution of middle web and side web is almost the same,while the diaphragm will change the shear force distribution on CSW,and the shear stress distribution near the diaphragm will be more uniform.The research conclusions can provide reference for the analysis of shear stress and bearingshear ratio of variable cross-section CSW.