ANALYSIS OF THE DYNAMIC BEHAVIOUR OF T-BEAM BRIDGE DECKS DUE TO HEAVYWEIGHT VEHICLES

This study investigates the dynamic behaviour of concrete T-beam bridge decks due to heavyweight vehicles. The three-dimensional model of an actual T-beam bridge deck design is implemented within the context of the finite element method, through use of the ANSYS 5.4 computer code. The deck is modeled with 20-node brick elements. Axle loads and configurations which correspond to the “permit vehicle” loading model are adopted for the vehicle model. The case study is considered for static, free vibration, and forced vibration analysis. The dynamic loading for forced vibration analysis is a harmonically (sinusoidal) varying load with magnitude equal to 10% of the axle load and a forcing frequency equal to the first(fundamental) frequency of the bridge deck, thus simulating a case of resonance. Dynamic amplification factors are evaluated at certain locations on the bridge deck for vertical displacement, normal stress in the longitudinal direction, and shear stress. Numerical results show a general trend for higher values than those specified by the AASHTO design code. It is also concluded that the values of dynamic amplification factors are response dependent, which suggests the use of three different types of dynamic amplification factors for the analysis of bridge decks.