横向偏位对截面不对称槽形PC梁受力的影响

为了研究梁体横向偏位对截面不对称PC （prestressed concrete）开口薄壁梁顶推施工的影响，并提出合理纠偏阈值，以世界首例顶推施工的不对称截面槽形梁——天津第二大街跨津山铁路立交工程为背景，利用有限元软件ANSYS建立实桥模型，研究槽形梁在最不利状态下未发生横向偏位时受力状态，在此基础上以满足安全落梁的横向偏位距离为最大偏位距离，分析不同横向偏位方式对梁体受力的影响. 研究结果表明:槽形梁在未发生偏位时横截面受力不均衡，而平动向右偏位方式加剧受力的不均衡；梁体以最不利偏位方式偏移96 mm后，槽型梁整体内力变化值较小，且下一步顶推后可以安全落梁. 因此，认为顶推施工中，横向偏位纠偏阈值可适当放宽至96 mm. 

Effect of Transverse Deflection on Force State of Prestressed Concrete Trough Girders with Asymmetric Cross-Section

This work aims to study the influence of transverse deflection of a beam body on pushing construction of an prestressed concrete (PC) open thin-walled beam with asymmetric cross-section and provide a reasonable deviation correction threshold for the incremental launching technique. Taking as a prototype the world’s first case of an asymmetrical cross-section trough girder—Tianjin Second Avenue Cross-Jinshan Railway Interchange Project, an actual bridge model was built using the finite element software ANSYS to study the stress state of the trough girder under the most unfavourable conditions. On this basis, using the maximum deviation distance that meets safety requirements for girder placement as the deviation limit, the influence of different transverse deflection modes on the force of the beam body was analysed. Results show that the cross-section force of the trough girder is not balanced when the deflection does not occur; however, the force imbalance is aggravated by translation to the right. When the most unfavourable transverse deflection occurs in the beam with a displacement of 96 mm, the internal force change of the trough girder is small. Therefore, it is suggested that the transverse deviation correction threshold could be relaxed to 96 mm in jacking construction.