Analysis Of Dynamic Response And Damage Factors Of Assembled Piers Under Explosion Load

With the progress of society and the development of economy,highway bridges play an increasingly significant role in today ’s transportation system.In the context of today’s peaceful development,there are still threats of war and terrorism.Since bridges play a key role in transportation,the fight against bridges has become one of the preferred targets of wars and terrorist attacks.As the key bearing component of the bridge structure,the pier column will directly lead to the overall collapse once the damage failure or damage occurs.Therefore,this paper takes the assembled pier with good recovery performance,fast construction speed and high safety factor as the research object,and uses ANSYS / Workbench to establish the anti-explosion numerical model of the assembled pier.The anti-explosion performance of the assembled pier is systematically studied from the aspects of the generation and propagation of the explosion shock wave,the dynamic response of the pier and the analysis of the damage factors.The main research contents and results are as follows :(1)The whole process of explosion shock wave generation and propagation is simulated by numerical analysis,and the influence of rigid ground and free air on the propagation of explosion shock wave is analyzed.The results show that due to the reflection of rigid ground,the peak value of explosion shock wave overpressure is 7-9times larger than that of free air,the peak arrival time is shortened by 10 %,the propagation speed is obviously accelerated,and the attenuation speed is obviously slowed down.(2)The finite element model of assembled pier under the action of rigid ground explosion shock was established by fluid-solid coupling analysis method in ANSYS /Workbench.The rationality of numerical simulation analysis method,material model and material parameters is verified by the existing explosion test.The dynamic response of the assembled pier is studied.The results show that the comprehensive reduction of the maximum displacement of the assembled pier under the explosion load is 34.4 %,25.5 %,22.9 % and 23.4 % respectively by increasing the prestress,increasing the number of segments,arranging the edge of the prestressed steel bundle and setting the shear key.The comprehensive reduction of residual displacement is 25.8 %,51.5 %,3 % and 36.8 % respectively,which can improve the anti-explosion performance of the assembled pier.Compared with the integral pier,the assembled pier has better anti-explosion performance,and the maximum displacement and residual displacement are reduced by 19.2 % and 102.4 % respectively.When the explosive core is high,the inclination of the upper section of the pier is large,which has a great influence on the upper structure of the bridge.(3)Based on the residual bearing capacity of the pier,the failure parameter D is proposed as the anti-explosion index,and the explosive equivalent,the distance of the explosion center,the height of the explosion center,the initial prestress,the number of segments and the setting of the shear key are taken as the damage factors.The influence of six factors on the damage degree of the pier is analyzed.On this basis,the grey correlation analysis method is used to measure the index and contribution of the correlation degree between the damage factors of assembled piers under explosion load.The results show that the comprehensive reduction rate of failure parameter D is 32.1 %and 29.6 % by increasing the initial prestress and setting shear keys between segments,which can effectively reduce the damage of pier columns and have a good correlation with the anti-explosion damage of assembled piers.The comprehensive reduction rate of the failure parameter D is 12 % and 7.2 %,and the correlation is not high.The comprehensive correlation degree of the influence of six factors on the damage of assembled piers under explosion load is from large to small : TNT equivalent,explosion center distance,explosion center height,initial tension prestress,shear key setting and segment number.In the anti-explosion design of assembled piers,priority can be given to factors with high correlation,such as increasing the initial tension prestress and setting shear keys.The grey correlation analysis method has certain reference value for the analysis of damage factors of assembled piers under explosion load.