基于不同规范下大跨钢箱梁人行桥动力响应分析

Analysis of A Long-span Steel Box Girder Footbridge Based on Different Specifications

目前各国规范中规定的人行荷载模式并不统一,它们之间存在一定的差异性,现有不同规范下对人行荷载作用下人行桥动力响应的对比研究甚少。以一频率处在行人步频范围之内的大跨钢箱梁桥梁为例,对比研究了包括国际标准化组织ISO10137规范、德国EN03规范在内的五种不同规范人行荷载模式的动力响应。结果表明,在连续行走的工况作用下,不同的加载模式对人行桥产生的竖向加速度沿着跨度的变化趋势一致,都是先增大后减小,但总体而言,ISO10137规范给出的人行荷载模式对人行桥产生的加速度和位移响应较其他规范大,对于一些对振动舒适度要求较为严格的实际工程进行动力响应分析时建议首选;德国EN03规范荷载模式所产生动力响应对折减系数比较敏感,尤其是当外荷载在2.3~2.5Hz时,折减系数为零,该规范不再适用;在其余三种规范的荷载模式激励下,人行桥动力响应相对较小。

At present,specifications about pedestrian loads of different countries are not unified,thus there are differences between them.However,relative comparison analyses about footbridge dynamic response in the terms of different norms and different loads are rather few.Providing an instance of long-span steel box-girder footbridge which is within the scope of pedestrian’s stride frequency,this paper analyzes different dynamic responses under five pedestrian loading patterns including specifications issued by ISO10137 and German EN03 specifications.The results show that,under the action of continuous walking,the vertical acceleration caused by different loadingpatterns is consistent with the changing tendency of the span,which first increases and then decreases,but the loading pattern of ISO10137 has bigger acceleration and displacement responses on footbridge than the other loading patterns.Thusit indicates that ISO10137 specification should be adopted to conduct an analysis of dynamic response in the process of practical engineering which is more strict on vibration comfort.The loading pattern of German EN03 is more sensitive to the reduction factor,especially when the external load is at 2.3-2.5 Hz,the reduction coefficient is zero.The dynamic response of the footbridge is relatively small under the excitation of the loading patternsspecified by the other specifications.