Impact Fragility Analysis Of A Steel Reinforced Concrete Continuous Girder Bridge Under Vehicle Collision

Vehicle collision is one of the main causes of urban bridge damage.Previous vehicle-bridge collision accidents show that the damage of bridge pier caused by vehicle-bridge collision leads to the collapse of the whole bridge structure.At present,scholars mainly study the collision force and dynamic response of a bridge under vehicle impact,and few studies focused on the failure probability of a bridge under vehicle collision.Meanwhile,the influence of soil-structure interaction on the dynamic response and failure probability of bridge structure is seldom considered in the existing literature.In this work,impact fragility analysis to calculate the failure probability of a three-span steel reinforced concrete bridge under vehicle collision,in which,the uncertainty of material and impact velocity were considered through Latin Hypercube Sampling method,and soil-structure interaction is also taken into account.1.The accuracy of the finite element model and the material model are verified by simulating and analyzing the existing scholars’ reduced scale vehicle-bridge pier collision tests through the finite element method.The results show that the CSC model can accurately simulate the damage and dynamic response of concrete pier columns,which provides an experimental basis for accurately simulating the vulnerability of full-scale bridge under vehicle impact.2.The finite element models of different types of full-scale bridge structures and vehicles were established.The uncertainties of materials and impact velocity were taken into account by Latin hypercube sampling.The results show that soil-structure interaction has a great influence on the failure probability of the bridge under vehicle impact.When the vehicle speed is greater than a certain threshold,the failure probability of the bridge structure under various damage states increases significantly,especially when the vehicle tonnage is at 30 tons.The vehicle tonnage also has a great influence on the failure probability.When the vehicle tonnage is 30t and the impact velocity is 64km/h,the probability of the severe damage is about 10%.At the same speed,when the tonnage of the vehicle increases to 50 tons,the probability of serious damage increases to 88%.The tonnage of vehicle has great influence on the threshold value of impact velocity leading to each damage state.When the vehicle tonnage is 30 tons,the threshold of impact velocity is 61.5km/h to cause serious damage to the bridge structure.When the vehicle tonnage is 50 tons,the threshold is reduced to 56.1km/h.3.Through parametric analysis,the influence of pier diameter on failure probability is studied.The results show that under the same pier height and the same vehicle velocity,and tonnage,the failure probability of bridge pier decreases significantly with the increase of pier diameter.For moderate damage,when the vehicle crash speed reaches 57.6km/h and the piers with diameter of 1.4m,1.7m and 2.0m have corresponding damage overtaking probabilities of 81%,16%and 0%,respectively.For collapse,the vehicle impact speed reaches to 76.7km/h,and the damage probability corresponding to the piers with diameters of 1.4m,1.7m and 2.0m is 100%,71%and 10%,respectively.Therefore,increasing the diameter of pier column can effectively improve the collision resistance of bridge.This study provides a theoretical and methodological basis for evaluating the reliability and resilience of bridges under vehicle impact.