Experimental Study Of Differently Protective RC Piers Under Blast Loading

Recently, terrorist attacks or accidental explosion occurred frequently, which can cut off the whole transportation system. Bridge pier that is one of the important components in bridge structure produce the damage under explosion, which can cause the progressive collapse of the bridge. Therefore, there is great theoretical significance and practical value to conduct the experimental study on different protective piers under blast load.In this thesis, main studies have been done as follows:(1)The main types of explosion load and the interaction between the explosion and the structure are summarized. The empirical formulas of blast load at home and abroad are listed. The simulation study on the shock wave is conducted.(2)The experimental study at non-contact explosion and the contact explosion of eight large scale protective reinforced concrete piers were conducted at the filed site, mainly considering the scale distance (explosive weight), the thickness of the steel tube and CFRP cloth layer.(3)The numerical simulation of dynamic response of the different protective reinforced concrete piers was conducted at at non-contact explosion and the contact explosion. The concept design of the anti-explosion protection of the pier was disussed.The main conclusions are as follows:(1)The shock wave can reflect near the ground and can produce diffraction and reflection on the pier surface. The overpressure peak and impulse can increase with the decrease of the scale distance and are maximum at the front surface, but minimal at the back surface. The overpressure peak and impulse on the pier height shows the "scoop" type distribution and can be simplied into trapezoidal distribution.(2)The fitting formula of the overpressure peak under non-contact explosion is consistent with the empirical formula, which can be used as reference for pier blast design. The stiffness of the protective pier is greater than that of the non-protective pier and the internal force of the protective pier is less than that of the non-protective pier. The pier produce bending deformation firstly at the small doses, then the base of the pier produce shear failure at large doses, mainly dominated by the impulse.(3)The pier produce the local punching and erosion under contact exolosion. The steel tube protection and the CFRP protection can improve the blast resistance of the pier, however, the steel tube is better protection.(4)The explosion model of the nonlinear finite element can effectively predict the dynamic performace of different protective reinforced concrete pier at contact explosion and non-contact explosion. The numerical simulation is basically consistent with the experimental results, which is used for blast-resistance analysis of the protective pier.(5)The concept design suggestion of the reinforced concrete piers blast protection is put forward according to the local failure and the overall damge of the piers. The structural design suggestion of the reinforced concrete piers blast protection is put forward according to the bending failure and shear failure, which can be a protective reference for the real pier.