The triaxial nonlinear finite segment method for steel - concrete composite box beam considering slip was established according to continuum mechanics and mechanical behavior of composite box beam, taking account of the borderline deformation and the method of relative degree of freedom. The main idea is that the stubs are regarded as a layer of continuous medium and the panels of composite box beam as a subelement, the slip and its first derivative were modeled as generalized degrees of freedom at the nodes composite box beam element, with the section co -ordination between the overall deformation. Based on the theory of minimum potential energy, the element stiffness matrices and vector of nodal point force were formed. A nonlinear analysis program for composite box beam was worked out. The result shows that the method is reliable, easy to be used and divided, and suit for special nonlinear analysis of large - span composite box beam.%根据连续介质力学和组合箱梁力学行为特点,放弃周边不变形假定,采用局部自由度方法,建立考虑界面滑移影响的组合箱梁空间梁段有限单元法.将栓钉视为连续介质,组合箱梁各板件视为组合箱梁子单元,并将组合梁元端节点引入界面滑移及其一阶导数作为广义自由度,利用最小势能原理建立组合箱梁梁段单元刚度矩阵和荷载列阵.编制组合箱梁空间非线性计算程序.计算结果表明:该方法计算可靠,容易操作且网格划分灵活,适用于大跨度组合箱梁空间非线性计算分析.
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