| The number of vessel collision accidents with bridges has increased rapidly,which has been widely concerned in the society.The installation of anti-collision structures with good performance is an effective measure to absorb impact energy and protect bridge operation safety.At present,the anti-collision structures used in practical projects generally have some disadvantages,such as large design stiffness,damage to ship bow,local piercing failure of steel panel,and susceptibility to corrosion.Therefore,this paper proposes a new type of corrugated steel plate-steel clad composite anti-collision structure,which can provide a solution to the disadvantages of existing anti-collision structures,and has good protection effect and wide application prospects.In this paper,the performance of corrugated steel plate-steel clad composite anti-collision structures is investigated by pendulum impact test and finite element analysis.The main contents and conclusions are summarized as follows:(1)Four steel clad composite anti-collision units are tested by pendulum impact system to investigate the influence of corrugated steel plate and impact speed on anti-collision units.The piezoelectric force sensor is used to record the impact force,and the displacement gauges are used to record the structural displacement of anti-collision unit.Additionally,the whole process of pendulum impact anti-collision unit is recorded by high-speed camera.The test results show that increasing the impact speed of the pendulum(2m/s to 3m/s)increases the peak impact force and structural deformation by more than 30%.The corrugation steel plate is set to improve the overall deformation performance of anti-collision structures and absorb impact energy,and the deformation mode is changed from local deformation to overall deformation,reducing the occurrence of local damage.(2)The pendulum impact test of anti-collision units and the drop hammer impact test of scaled steel boxes in relevant literature are numerically simulated by using nonlinear finite element(FE)analysis software LS-DYNA.The simulation results are in good agreement with the test results in terms of impact force,displacement and structural deformation model.The simulation error of impact force peak value is within 8%.The results show that considering the steel strain rate effect is of great significance to accurately simulate the impact test results(the error reaches 20% when it is not considered).The effectiveness and reliability of the modeling method is verified on the low-speed impact of anti-collision structures,which provided a basis for subsequent analysis of anti-collision structures’ protective performance.(3)Based on the verified finite element(FE)modeling method,the parameter analysis of corrugated steel plate-steel clad composite anti-collision structures is carried out to evaluate its protective performance to an actual pier.The analysis results show that the installation of corrugated steel plate-steel clad composite anti-collision structures can significantly improve the structural response of the bridge pier in terms of peak impact force,pier column damage,pier bottom shear force and bending moment,and take into account the protection of ship bow.Under different vessel speed(1m/s to 5m/s)and vessel mass(500t to 2500t),the peak reduction rate of impact force is maintained at more than 30%,the duration of impact force increases by0.2s-0.5s,and the peak reduction of shear force and bending moment at pier bottom is 10% to40%;The number of wave crests of impact force curve is affected by the arrangement of bow longitudinal girder;Increase the thickness of steel panel(4mm to 12mm)strengthen the rigidity of anti-collision structures,reduce the impact depth and keep the peak reduction rate of impact force above 20%;The increase in the configuration of corrugated steel plates(0% to 48%)reduces the impact depth of anti-collision structures by 0.672 m while maintaining the same energy consumption level;In the oblique collision cases(15° to 45°),the anti-collision structures can effectively turn the bow of the ship,reduce the conversion value of ship kinetic energy to internal energy,and the peak reduction rate of impact force can reach more than 47%,forming protection for the ship,bridge and anti-collision structures.(4)The whole bridge model of a practical project is established,and two vessel types are used to evaluate the impact protection effect of the anti-collision structures in the practical project.The results show that the anti-collision structures can avoid the impact damage of bearing platform and pier concrete and reduce the damage degree of bow.The peak value of impact force decreases by 34.03% under normal collision condition and 48.66% under oblique collision condition;The collision surface of the anti-collision structures is deformed as a whole,and there is no local puncture.Steel panel,polyurethane core material and corrugated steel plate are the main energy consuming components of anti-collision structures;Vessel type and impact height restrict the performance of fixed anti-collision structures,and its fortification range should be reasonably optimized according to the above factors.The good protection effect of corrugated steel plate-steel clad composite anti-collision structures in the actual full-bridge collision simulation shows that it is expected to solve the common shortcomings of existing anti-collision structures,which has a wide application prospect. |
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