The Effect Of Key Structural Parameters On Dynamic Response Of The Flexible Crashworthy Device For Bridge Pier

The accident and potential risk of vessel colliding on bridge is increasing with the rapid development of transportation industry.The test results show that it is an effective measure to prevent collision on the pier.This paper targeted on the new-type flexible crashworthy device on bridges pier,set different simplified physical model to analyze:1)Simplify the crashworthy device to elliptical physical model: It constituted by two oval beams as inner and outer steel fence and anti-collision rings that evenly distributed and vertical to the steel fence.The inner fence is fixed on the pier,the outer fence is elastic beam,fences are connected through evenly distributed coil support connection.Proceed calculation of dynamic response of model under the action of impact load and analysis of the influence of dimensionless parameter to dynamic response.2)Simplify the crashworthy device to hexagonal physical model: It constituted by two similar hexagonal beams as inner and outer steel fence and anti-collision rings that evenly distributed and vertical to the steel fence.Consider the outer fence is rigid and anti-collision rings are large deformation spring.We analyzed the device’s horizontal movement under impact load;Discussed the influence of anti-collision rings’ mechanical properties to the dynamic response of device;Analyzed the maximum impact force under horizontal movement;Analyzed the device’s torsional performance under quasi-static condition,the device’s torsional stiffness will be significantly increased when the rotation surpassed 3°,then we further analyzed the coupling of horizontal movement and rotation under quasi-static condition.We further considered the outer fence is elastic and anti-collision rings are small deformation spring.We utilized Laplace transformation and Laplace value inverse transformation to calculate the dynamic response of model under the action of impact load and analyze the influence of equivalent bending stiffness of outer fence to the dynamic response of crashworthy device.Research shows: Under the effect of impact load,there is a critical equivalent bending stiffness existed on outer fence.When the critical equivalent bending stiffness reached the critical value,the fence is approximately considered as rigid,then we proceed analysis of outer fence’s structure parameters to the dynamic response of device.3)Established a finite element model of this device and compared it with the models to verify the feasibility of the simplified model.The analysis model can be used to estimate the key structural parameters of the new-type flexible crashworthy device on bridges pier,which provides a theoretical basis for determining the key parameters of the new-type flexible crashworthy device.