基于长期结构健康监测数据的大跨公铁两用桥梁交通荷载模型研究

汽车和列车荷载是大跨公铁两用桥梁服役中承受的主要活载，是导致桥梁疲劳劣化的最主要原因，在桥梁设计之初就要对其有准确把握。然而，由于大跨桥梁交通流复杂、随机性大，目前仍难以准确把握公路交通荷载；疲劳车辆荷载模型由于缺乏足够真实可靠的车辆荷载和结构响应数据也仍有待论证。本项目基于一座典型大跨公铁两用桥梁上测得的长期健康监测数据，借助有限元模型和结构分析理论，对以下几个方面进行深入研究。(1) 大跨桥梁公路交通静力荷载模型。除了长期WIM数据、典型交通监控录像，应变数据也将纳入研究体系，使荷载模型对应结构响应得以量化。(2) 公、铁路交通疲劳荷载模型。基于结构部件实测的长期应力时程直接得到应力谱，借助经监测数据校准后的有限元模型反算代表疲劳车辆模型荷载，可大大提高模型精度。(3) 国内外桥规交通荷载模型在本项目所研究桥梁基准上的比较。该项目为我国大跨公铁两用桥的设计和评估提供交通荷载依据。

Highway and railway loadings are the main live loads long-span road-rail bridges suffer in the service life, and they are the primary cause of bridge fatigue. Therefore, they should be correctly understood and fully considered in the design stage of the bridge. However, there is still no accurate grasp of the highway loading for long-span bridges because of the complexity and randomness of the traffic flow. Besides, since adequate monitoring data of vehicle loads and structural responses are absent, the fatigue vehicle models also remain to be demonstrated. Based on the long-term structural health monitoring (SHM) data collected from a typical long-span road-rail bridge, and the finite element model (FEM) of the bridge as well as the structural analysis theory, this project investigates the static highway loading for long span bridges, and the fatigue loadings of both highway and railway traffic. In addition to WIM data and video recordings of typical traffic conditions, strain data are also incorporated into the study of static highway loading model, which quantifies the model corresponding to the structural response. As for the fatigue vehicle models, their accuracy is greatly improved by the stress spectra obtained from strain data and the FEM calibrated by measured data. Taking the studied bridge as a benchmark, traffic load models in bridge codes worldwide will be compared and evaluated. This project will provide valuable reference of traffic load models for the design and assessment of long-span road-railway bridges in our country.