基于静动力模型修正的简支梁桥承载力评定方法

Simple-supported Beam Bridge Bearing Capacity Assessment Method Based on Static and Dynamic Model Modification

为快速完成对桥梁安全状况的评定,采用基于静动力试验模型修正的方法对某装配式钢筋混凝土简支梁桥进行桥梁承载力评定。利用单辆车缓慢驶过桥面测得桥梁关键测点的挠度影响线,基于环境激励对桥梁进行模态测试,测得桥梁的前5阶自振频率,依据图纸建立桥梁的初始有限元模型,利用现场实测挠度影响线和频率修正初始有限元模型,得到代表桥梁实际工作状态的基准有限元模型;在基准有限元模型上施加与传统荷载试验相同的试验荷载,计算得到修正后桥梁的挠度和应变响应,根据相关评定规程计算实际桥梁的校验系数,从而评定桥梁承载力。结果表明:联合单辆重车实测位移影响线和频率进行模型修正,能够得到精准的有限元修正模型;利用静动力模型修正的模型对桥梁进行承载力评定的评价结果与传统荷载试验非常接近,精度达到90%以上,该评定方法省时省力、便捷快速,具有很强的高效性与可行性。

In order to complete the evaluation of bridge safety quickly,the method based on static and dynamic test model correction was used to evaluate the bearing capacity of a fabricated reinforced concrete simply-supported beam bridge.Using a single vehicle to drive slowly across the bridge deck,the deflection influence line of key measuring points of the bridge was measured,the modal test on the bridge based on environmental excitation was conducted,and the first five natural vibration frequencies of the bridge were measured.The initial finite element model of the bridge according to the drawings was established,and the benchmark finite element model representing the actual working state of the bridge was obtained by using the field measured deflection influence line and frequency modified initial finite element model.The same test load as the traditional load test was arranged on the benchmark finite element model,and the deflection and strain response of the modified bridge were calculated.The verification coefficient of the actual bridge was calculated according to the relevant evaluation regulations,so as to evaluate the bearing capacity of the bridge.The results show that the accurate finite element correction model can be obtained by combining the measured displacement influence line and frequency of a single heavy vehicle.The evaluation results of bridge bearing capacity evaluation using the model modified by static and dynamic models are very close to the traditional load test,and the accuracy is more than 90%.The evaluation method is time-saving,labor-saving,convenient and fast,and has strong efficiency and feasibility.