Determination of impact factor for steel railway bridges considering simultaneous effects of vehicle speed and axle distance to span length ratio
Determination of impact factor for steel railway bridges considering simultaneous effects of vehicle speed and axle distance to span length ratio
复制标题
DOI：
10.1016/j.engstruct.2010.01.015
复制
发表时间：
2010-05
影响因子：
5.5
通讯作者：
S. A. Hamidi;Farhad Danshjoo
中科院分区：
文献类型：
--
作者：
S. A. Hamidi;Farhad Danshjoo
在常用的桥梁分析方法中，交通荷载被认为是增加了一个影响因子的静荷载。根据现行规范，冲击系数只是桥梁跨长或首振频率的函数。本文研究了速度、车轴距、车轴数、跨长等参数对铁路钢桥动力响应的影响及影响因子值。在此基础上，计算了4座跨度分别为10、15、20和25 m的桥梁在车速为100-400 km/h、轴距为13 - 24 m的列车下的动力响应和影响因子。动力分析结果表明，在大多数情况下，计算出的冲击系数值高于相关规范的推荐值，因而低估了冲击系数提供的定量。列车速度对冲击系数也有一定的影响，随着列车速度的增加，冲击系数的值会有较大的增加。影响因子的另一个有效因素是列车轴距与桥梁跨距的比值，使得影响因子值在小于1和大于1时发生变化。在共振条件下，车轴列数只影响冲击系数。本文给出了考虑速度、列车轴距和桥梁跨距等参数影响系数的关系式。
In common bridge analysis method, traffic load is considered as a static load increased by an impact factor. Impact factor is just a function of span length or the first vibration frequency of the bridge according to the present codes. In this paper the effects of various parameters including velocity, train axle distance, the number of axles and span lengths on dynamic responses of railway steel bridges and also impact factor values are studied. In this regard dynamic responses and impact factors for four bridges with 10, 15, 20 and 25 m span lengths under trains with 100–400 km/h velocity and axle distance between 13 to 24 m have been calculated. Dynamic analysis results show that in most cases the calculated impact factor values are higher than that recommended by the relevant codes and so the offered rations for impact factor are underestimated. It has also been shown that the train velocity affects the impact factor, so that the value of impact factor rises incredibly with the train velocity. Another effective element for impact factor is the ratio of train axle distance to bridge span length so that the impact factor value varies for the ratio below and above unity. The train number of axles just affects the impact factor under resonance conditions. In this paper some relations are offered for the impact factor considering parameters: velocity, train axle distance and the bridge span length.