钢-混凝土组合箱梁梁段有限元法研究

The finite segment method study of steel-concrete composite box beams

组合梁界面滑移将减小组合梁刚度,增大变形,影响构件性能;剪应力沿截面横向分布不均匀,造成其弯曲正应力的横向分布呈曲线形状,即剪力滞效应;同时组合梁往往重载,具有较小的跨高比,剪切变形不可忽略。根据虚功原理,建立了同时考虑滑移效应、剪力滞及剪切变形效应的组合梁单元刚度矩阵及等效节点力向量,并在此基础上编制了组合梁梁段有限元程序。利用本文程序对现有组合梁试件的混凝土顶板应力、钢梁底板应力、跨中挠度和梁端滑移进行了计算,并将本文计算结果与解析法计算结果及试验结果进行了比较。结果表明,本文计算结果与解析法计算结果及试验结果吻合良好;同时,本文计算结果具有较好的稳定性,验证了本文计算方法的正确性。本文所建立的梁单元刚度矩阵同时考虑了剪切变形、剪力滞及滑移效应的影响,符合工程实际,为有限梁段法分析组合箱梁提供了理论基础。

The interface slip of composite beam would reduce the stiffness and increase the deformation, which affects the component performance. The transverse distribution of the bending normal stress pres- ents curve shape because of uneven transverse distribution of shear stress,i, e. shear lag effect. Because the composite beam with small span-depth ratio is often overloaded, the shear deformation cannot be ig- nored. According to the virtual work principle, the unit stiffness matrix and equivalent nodal force vector of the composite beam were established in consideration of the slip effect,shear lag effect and shear de- formation. On the basis of the unit stiffness matrix mentioned in this paper, the Finite Segment Method program of composite box beam was performed. The stress of concrete roof and steel beam floor, mid- span deflection and slip of beam-end were calculated based on this program. And the calculated results were compared with calculating results of analytic-method and experimental results. The results show that the calculating results in this paper are in good agreement with the experimental results and the re- suits of analytical-method, and it has good stability. The correctness of the calculation in this paper is verified. The unit stiffness matrix considering the influence of shear deformation, shear lag and slip ac- cords with engineering practice,which provides a theoretical basis for using finite beam segment method to further study of the composite box beams.