Experimental Study On Blast Resistance Of Prestressed Concrete Continuous T Beams

As the lifeline engineering of traffic,the threat of explosion to bridge is increasingly serious.Once the explosion load occurs,it will cause heavy casualties and property loss.Prestressed concrete continuous T beam bridge is one of the most widely used bridges in China's highway engineering,and the study on its antiknock performance is of great significance and practical value.The main Tasks are described as following:(1)The numerical simulation and experiment are used to study the propagation of blast shock wave in the air and the interaction with the prestressed concrete continuous T beam bridge.The distribution characteristics of the explosion load(shock wave overpressure and impulse)on the bridge surface are analyzed.(2)A model of 2*8m two span prestressed concrete continuous beam bridge is designed and made,and the field explosion test is carried out.The dynamic response characteristics,damage mechanism and failure mode of the prestressed concrete continuous T beam bridge under the explosive load of the bridge face with Different Detonation positions are studied by the numerical simulation method.(3)Based on the equivalent single degree of freedom method,the damage of prestressed concrete continuous T beam bridge under the explosion load of bridge deck is analyzed and evaluated.The main conclusions of this paper are as follows:(1)The explosion at the top of the bridge can be considered to be an explosion in the free air field.When the height of the core is constant,the explosion load of the bridge increases sharply with the decrease of the proportion distance.When the proportion distance is constant,with the increase of the explosive equivalent,the overpressure peak value at the bottom of the core is unchanged,but the overpressure at the other position of the bridge surface is overpressure.The peak value is significantly increased,and the overpressure peak formula for bridge deck blasting load model is established,which can provide reference for the design of bridge deck explosion.(2)The explosion at the top of the bridge can be considered to be an explosion in the free air field.When the height of the core is constant,the explosion load of the bridge increases sharply with the decrease of the proportion distance.When the proportion distance is constant,with the increase of the explosive equivalent,the overpressure peak value at the bottom of the core is unchanged,but the overpressure at the other position of the bridge surface is overpressure.The peak value is significantly increased,and the overpressure peak formula for bridge deck blasting load model is established,which can provide reference for the design of bridge deck explosion.(3)When the explosion occurs on the bridge surface,the enhancement of the concrete strength,the prestress and the width span ratio can reduce the local damage degree of the beam to a certain extent,and improve the anti explosion performance of the bridge.The encrypt arrangement of the stirrup can improve the anti explosion performance of the main beam to a certain extent and reduce the dynamic response of the beam,but it can be used for the bridge surface caused by the explosion of the hinge joint.The plate failure has not improved.(4)Based on the equivalent SDOF method and the displacement criterion,the damage assessment of the prestressed concrete continuous beam bridge is carried out.When the explosion is encountered,the damage degree of the bridge can be evaluated quickly as long as the peak and impulse of the characteristic point of the explosion are determined,which can provide the basis for the anti explosion protection of the beam bridge.