Effects of random road surface roughness and long-term deflection of prestressed concrete girder and cable-stayed bridges on impact due to moving vehicles

The effects of random road surface roughness and long-term deflection of prestressed concrete bridges on the impact effects due to moving vehicles are investigated. The concrete bridges studied include multi-span girder bridges and cable-stayed bridges. The random road surface roughness is described by a zero-mean stationary Gaussian random process, while the long-term deflection of the concrete deck is represented as a kind of global roadway surface roughness in the study. The bridge is modelled by finite element method. Each moving vehicle is idealised as a one-foot dynamic system, in which a mass is supported by a spring and a dashpot. Numerical results show that the effect of random road surface roughness on the impact induced by moving vehicles is significant in the girder bridges, while that of the long-term deflection of concrete deck is small to moderate. The impact effects of the random road surface roughness and the long-term deflection of concrete deck on a cable-stayed bridge vary a lot depending on the location. In general, such effects on the bridge deck are more significant at sections closed to the bridge towers. Such effects on the bending moment at the tower base are also significant. The effects on the stay cables vary much, with significant effects on the short cables and negligible effects on the longest cables. (C) 2001 Elsevier Science Ltd. All rights reserved.