Load Distribution Factors of Simply Supported Concrete T-beam Bridges under Typical Freight Vehicle Loads

Accurate evaluation of load distribution behavior is crucial to the safety evaluation and normal operation of short-and medium-span concrete girder bridges.In this study, 3D finite element analysis was performed to calculate the load distribution factors (LDFs) for a sample of reinforced concrete T-beam bridges under representative typical freight vehicles and the results were compared with those obtained by the American Association of State Highway and Transportation Officials (AASHTO) specification.The parameters that influenced the LDF, namely, transverse loading position, bridge span length, and vehicle type, were analyzed.Results demonstrate that the transverse loading position has a considerable influence on the LDF.The LDF of the interior girder decreases by 45% when the vehicle moves from the centerline of the bridge to the side of the barrier.For the 20 m T-beam bridge, the LDFs of the interior and exterior girders reach the maximum value in the allowable range of the vehicle transverse position, and with the increase in span length, LDF decreases gradually.Among all the loading vehicles, the three-axle truck has the largest LDF, which decreases with the increase in the number of axles.Compared with the LDF in the AASHTO specification, the LDF obtained by finite element analysis is reduced by 24.5%-40.3%,and this reduction can effectively improve the load rating level of bridges in service.The proposed method provides a valuable reference for the safety assessment of bridges in service, which can effectively avoid unnecessary maintenance and reconstruction of old bridges.