我国快速发展的经济对铁路运输能力的要求不断提高,既有铁路重载扩能运输改造进程不断推进,随之提高的列车轴重必然会降低既有铁路桥梁的活载储备量,从而导致T梁的整体刚度和耐久性下降.通过对不同跨径桥梁活载储备量的计算分析,进而选取跨度12 m混凝土T梁作为研究对象进行静力适应性分析,对梁体跨中截面主筋应力、梁体跨中截面上翼缘混凝土压应力及梁体跨中底板裂缝宽度进行检算;并且建立动力有限元模型,分析不同列车荷载作用对跨中横向加速度及横向振幅的影响规律,并与试验实测结果进行对比分析.研究结果表明:在270 k N和300 k N轴重重载列车作用下,梁体受拉钢筋最底部主筋应力均超过容许值;结构动力响应随着车辆轴重增大而增大; 12 m跨低高度简支钢筋混凝土梁横向动力适应性优于普通高度简支梁,两者均满足开行大轴重重载货车要求.%With the ever-growing demands for railway transportation capacity due to the economic development in China, the capacity expansion and transport transformation of existing heavy haul railways continue to be carried forward.The increasing axle load of trains will result in continuous reduction of the live load reserves of existing railway bridges, which will inevitably lead to overall reduction of stiffness and durability of T-beams.Based on the calculation of live load reserves of different span bridges, this paper selects 12 m concrete T-beam as the research object to carry out static adaptability analysis, and calculates the main reinforcement stress of the girder mid span section, the compressive stress of the upper flange concrete of the mid span section of the girder, and the crack width of the mid span floor of the beam body.The finite element model is also established to analyze the effects of different train loads on the mid-span lateral acceleration and lateral amplitude.Finally, contrastive analysis of the measured test data is conducted.The results show that the stress on the bottommost tendons of the tensile reinforcement of the beam exceeds the allowable values under the loads of trains with 270 kN and 300 kN axle loads;the structural dynamic response increases with the increase of the axle load;the lateral dynamic adaptability of the 12 m simply-supported reinforced concrete beam with a low height is superior to that of the simply supported beam with an average height, and both of them meet the requirements for heavy haul freight with large axle loads.
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