杭州市跨京杭运河高架桥为(37+60+37)m连续钢箱梁桥,钢箱梁总重约932 t.为解决钢箱梁运输难题、加快施工进程,该桥钢箱梁采用纵向分段、横向分块施工方案,钢箱梁横向采用错位分割.为提高梁段的刚度并降低各梁段刚度的差异,提出剪刀撑加强方案,即在梁段的腹板与顶板开口处及缺失腹板处沿顺桥向增设剪刀撑.为分析剪刀撑加强方案的可行性,采用MIDASCivil建立中跨有限元模型,分析吊装及安放过程中各梁块跨中处的位移与应力,并对实桥应力进行监测.结果表明:采用剪刀撑加强方案后,各梁块的变形和应力均较为协调,满足后续横向焊接施工要求;结构应力处于安全范围.实践证明,剪刀撑加强方案能够满足钢箱梁横向分块施工的控制要求.%The Beijing-Hangzhou Grand Canal Viaduct in Hangzhou City is a continuous steel box girder bridge with span arrangement (37+60+37) m and with the part of the steel box girder totally weighing about 932 t.To solve the transportation problem of the girder in the construction and accelerate the construction progress of the bridge,the scheme of constructing the girder in segments in the longitudinal direction and in blocks in the transverse direction was adopted and in the transverse direction,the girder was staggeredly cut and divided.To improve the stiffness and reduce the stiffness differences of the segments of the girder,the scheme of the X-bracing stiffening for the segments was proposed.That was,the X-bracings were arranged at the openings of the webs and top plates or at the parts with no webs of the segments along the bridge.To check the feasibility of the scheme of the X-bracing stiffening,the MIDAS Civil was used to set up the finite element model for the central span of the bridge,the displacement and stress of the blocks at the midspan in the process of hoisting and installation were analyzed and the stress of the bridge was monitored.The results reveal that after the scheme of the X-bracing stiffening is applied,the deformation and stress of the blocks are compatible,can satisfy the following construction of the welding in the transverse direction and the stress of the structure is in the safety range.Practice proves that the scheme of the X-bracing stiffening can satisfy the control requirements for construction of the girder in blocks in the transverse direction.
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