tailieunhanh - Impact Effect of Moving Vehicles

Impact Effect of Moving Vehicles Mingzhu Duan Quincy Engineering, Inc. 56 Philip C. Perdikaris Case Western Reserve University Introduction Consideration of Impact Effect in Highway Bridge Design Consideration of Impact Effect in Railway Bridge Design Free Vibration Analysis Structural Models • Free Vibration Analysis Wai-Fah Chen Purdue University Forced Vibration Analysis under Moving Load Dynamic Response Analysis • Summary of Bridge Impact Behavior Introduction Vehicles such as trucks and trains passing bridges at certain speeds will cause dynamic effects, among them global vibration and local hammer effects. The dynamic loads for moving vehicles are considered “impact” in bridge engineering because of the relatively short duration | Duan M. Perdikaris . Chen W. Impact Effect of Moving Vehicles. Bridge Engineering Handbook. Ed. Wai-Fah Chen and Lian Duan Boca Raton CRC Press 2000 56 Impact Effect of Moving Vehicles Introduction Consideration of Impact Effect in Highway Mingzhu Duan Quincy Engineering Inc. Philip C. Perdikaris Case Western Reserve University Wai-Fah Chen Purdue University Bridge Design Consideration of Impact Effect in Railway Bridge Design Free Vibration Analysis Structural Models Free Vibration Analysis Forced Vibration Analysis under Moving Load Dynamic Response Analysis Summary of Bridge Impact Behavior Introduction Vehicles such as trucks and trains passing bridges at certain speeds will cause dynamic effects among them global vibration and local hammer effects. The dynamic loads for moving vehicles are considered impact in bridge engineering because of the relatively short duration. The magnitude of the dynamic response depends on the bridge span stiffness and surface roughness and vehicle dynamic characteristics such as moving speed and isolation system. Unlike earthquake loads which can cause vibration in bridge longitudinal transverse and vertical directions moving vehicles mainly excite vertical vibration of the bridge. Impact effect has influence primarily on the superstructure and some of substructure members above the ground because the energy will be dissipated effectively in members underground by the bearing soils. Although the interaction between moving vehicles and bridges is rather complex the dynamic effects of moving vehicles on bridges are accounted for by a dynamic load allowance IM in addition to static live load LL in the current bridge design specifications 1-3 . According to the American Association of State Highway and Transportation Officials AASHTO and the American Railway Engineering Association AREA specifications D. IM -1 Dst where Ddyn is the maximum dynamic response for deflection moment or shear of the .