Abstract:The steel girder bridge has been commonly applied in the construction of expressways in China. The composite type of steel box girders / I-girder and concrete bridge deck is usually used for the structure. Because of the delayed development of this bridge type, there is no suitable basis for the impact factor which must be considered in its design. Therefore, the pulsation and vehicle tests are conducted on a steel-concrete composite I-girder simple-supported girder bridge in Yanchong Expressway. The vehicle-bridge coupled vibration analysis model is established by using the ABAQUS finite element software, and its accuracy is verified through the actual bridge tests. Based on this, four models of simple-supported girder bridges with the identical spans, design loads, and similar bridge widths are established for steel-concrete composite box girder bridge, steel-concrete composite I-beam bridge, prestressed concrete (small) box girder bridge and prestressed concrete T-girder bridge. Through the vehicle-bridge coupled vibration analysis, the effects of varying pavement roughness and vehicle speed on the impact factors of four simple-supported girder bridges are compared, and at the same time, compared with the impact factors related to frequency given by Chinese standards. The research reveals that the prestressed concrete T-beam bridge shows the higher impact factors, and the impact factors of the other three simple-supported girder bridges have the good consistency. It is suitable to utilize the existing specifications for calculating the impact factors of steel-concrete composite simple-supported girder bridges at a higher level of pavement roughness.
