超大跨度公铁两用桥梁公路荷载折减系数的研究

Study on Highway Load Reduction Coefficient for Super⁃long Span Rail⁃cum⁃Road Bridge

超大跨度铁路桥梁设计时如果仍沿用TB 10002—2017《铁路桥涵设计规范》中公路荷载折减系数的规定会造成活载效应折减过大,降低结构安全度。本文以简支梁为基本结构,建立不同跨度的计算模型,以与TB 10002—2017适用范围内活载折减效应总体相当为原则,计算超大跨度公铁两用桥梁公路荷载的折减系数。研究结果表明,跨度为150~550 m时,公铁两用桥梁采用公路荷载折减系数0.75后,平均活载效应比未折减时减少了5%。建议双线、四线铁路荷载与公路荷载组合的公铁两用桥梁,跨度为150~600 m时,公路荷载折减系数分别取0.85、0.75;跨度为3 000 m时,公路荷载折减系数均取0.90;其余跨度时的折减系数按照线性插值。

If the highway load reduction coefficient in TB 10002—2017 Code for Design on Railway Bridge and Culvert is still used in the design of super-long span railway bridges,the live load effect will be reduced too much and the structural safety will be reduced.Taking simply supported girder as the basic structure,the calculation models of different spans were established to calculate the highway load reduction coefficient of super-long span rail-cum-road bridge based on the principle that the live load reduction effect is equivalent to that of TB 10002—2017.The research results show that when the span is 150~550 m,the average live load effect of rail-cum-road bridge is reduced by 5%compared with that without reduction when the highway load reduction coefficient is 0.75.For the double-track,quadruple track railway load and highway load combination of rail-cum-road bridge,when the span is 150~550 m,the average live load effect of rail-cum-road bridge is reduced by 5%when the highway load reduction coefficient is 0.75.When the span is 150~600 m,the highway load reduction coefficients are 0.85 and 0.75 respectively.When the span is 3000 m,the highway load reduction coefficient of both bridges is 0.90.The reduction coefficients of other spans are linear interpolation.