重载铁路桥梁动力响应的随机性分析及最大值估计

Randomness Analysis and Maximum Estimation for Dynamic Response of Heavy Haul Railway Bridge

为评估现有桥梁通行大轴重列车的可行性,基于某重载铁路桥梁的现场试验数据,对不同轴重列车以不同运行速度通过桥梁时桥梁动力响应的随机性进行分析,并且结合3倍标准差原理进行动力响应最大值估计。结果表明:在60~80km·h^(-1)的速度范围内,列车速度对桥梁的竖向挠度和横向振幅影响不大;随着列车速度的提高,桥梁的竖向振幅缓慢增加,而且桥梁跨中的横、竖向强振频率和振动加速度也呈逐渐增大趋势;随着货车轴重的增加,桥梁的竖向挠度呈近似线性增加趋势,振幅和振动加速度也不断增大;25t轴重运营列车引起的桥梁动力响应的概率密度离散程度较大,而试验列车的离散程度较小;在相同列车速度条件下,跨中的横向响应比竖向响应的随机性大,振幅和振动加速度的随机性相当,竖向挠度的随机性最小;对1座孔跨布置为2-24m的低高度预应力混凝土T型简支梁桥的动力响应最大值估计的结果表明,该桥能够通行75km·h^(-1)速度以下的30t轴重列车。

In order to evaluate the feasibility for heavy axle load trains passing through existing bridges, the randomness of bridge dynamic response was analyzed under different speeds and different axle loads of trains based on the field test data of a heavy haul railway bridge. Meanwhile, the maximum value o{ dynamic response was estimated combined with the triple standard difference method. Results show that train speed has little effect on the vertical deflection and lateral amplitude of the bridge within the speed range of 60 to 80 km h-1. As the train speed increases, the vertical amplitude of bridge increases slowly, meanwhile, the transverse and vertical vibration frequency of midspan together with the vibration accelera- tion of bridge are gradually increased. As the axle load of freight train increases, the vertical deflection of bridge almost increases linearly. Both the amplitude and vibration acceleration have an increasing trend at the same time. The probability density discrete degree of bridge dynamic response caused by in service train with the axle load of 25 t is higher than that caused by test train. At the same speed, the transverse response of midspan has higher randomness than vertical response. The randomness of amplitude is equal to that of vibration acceleration. The randomness of vertical deflection is the lowest. For a 2--24 m low height prestressed concrete simply-supported T beam bridge, the maximum value estimation indicates that trains with 30 t axle load can pass through the bridge when the speed is below 75 km h-1.