Development of Time History Analysis for Dynamic Demand of Elevated Pilecap Bridge Subjected to Vessel Collision

Abstract:

Generalpurpose nonlinear finiteelement model is characterized by its low efficiency and material,geometric and boundary nonlinear behaviors in shipbridge collision,which is unacceptable to engineers.An alternative timehistory approach is presented to rapidly and reliably evaluate the dynamic demand of bridge structure under ship impact.Energy conservation and momentum conservation equations are established based on the model of two degrees of freedom(DOFs).Then,based on energy conservation equation and the relationship between dynamic impact force to crush depth(namely,curve),the maximum crush depth is determined and the structural elastic potential energy is also discussed.According to the assumed timecrush depth relationship during loading and timeimpact force relationship during unloading,formulae of the time duration of loading and unloading under ship collision are obtained.A procedure of calculating the dynamic demand of bridges is proposed for practical project.Results show the dynamic responses of structure by the proposed method are in agreement with the shipbridge collision model,but the computation efficiency is improved obviously.