基于影响矩阵法的斜拉桥斜拉索合理初始张拉力分析

Analysis of Rational Initial Tensioning Forces Based on Influence Matrix Method for Stay Cables of Cable-Stayed Bridge

针对斜拉桥建模过程中斜拉索内力与设计成桥索力存在偏差的问题,为确定斜拉索合理的初始张拉力,提出基于影响矩阵法的斜拉索合理初始张拉力计算方法。该方法根据斜拉索张拉过程中其两端的位移和索力协调关系,构建一种影响矩阵,通过该矩阵计算斜拉索的合理初始张拉力。以某大跨度独塔斜拉桥为例,采用该方法计算斜拉索合理初始张拉力,并对比分析了施加不同初始张拉力后的斜拉索内力;考虑该方法确定的初始张拉力和将设计成桥索力作为初始张拉力的2种工况,分析不同初始张拉力对桥梁结构响应的影响。结果表明:该方法计算得到的斜拉索内力与设计成桥索力相对差值小于0.01%;初始张拉力对桥梁结构变形和斜拉索内力影响显著,在斜拉索中施加该方法确定的初始张拉力,可使斜拉索内力达到设计成桥索力。

For the cable-stayed bridge,the stay cable internal forces during construction are not exactly the same with the stay cable forces in the completed bridge state.To address the deviation,a calculation method to determine rational initial tensioning forces of stay cables that is based on influence matrix is proposed,which takes the correlation of girder-end displacement and stay cable forces during the stay cable tensioning process to establish an influence matrix to calculate the rational tensioning forces of the stay cables.The method was used to calculate the rational initial tensioning forces of stay cables of an example long-span single-pylon cable-stayed bridge,and the internal forces of stay cables under different initial tensioning forces were compared and analyzed.The influence of different initial tensioning forces on the bridge structure response was analyzed in the contexts,namely with the initial tensioning forces determined by the proposed method and with the cable forces in the completed bridge state.The results show that relative deviation between the internal forces of stay cables calculated by the proposed method and the design cable forces in the completed bridge state is less than 0.01%.Initial tensioning forces can exert significant influence on the structural deformation of the bridge and the internal forces of stay cables.The stay cables of the example bridge were tensioned with initial forces calculated by the proposed method,as a result,the internal forces of the stay cables reach the design values for the completed bridge.