Experimental and finite element analysis of the explosion load model for prestressed concrete box girders

At present, there are few researches on the blast pressure load and shock wave propagation in box girders. Based on the engineering background of a prestressed concrete box girder bridge which is widely used in concrete bridge design at present, the explosion load test of the prestressed box girder was carried out with a scale of 1: 5. The experimental results show that the overpressure on the top plate of the box girder exhibits a non-linear descending gradient distribution along the longitudinal direction of the box girder, and the overpressure is distributed along the transverse direction of the box girder as an approximate trapezoidal load. As the proportional distance decreases, the overpressure increases gradually. Based on the explosion load test of the box girder, a three-dimensional numerical analysis model of box girder explosion was established. The accuracy of the numerical simulation was verified by comparing the numerical analysis results with the experimental data. Based on the numerical results, the interaction mechanism between the blast wave and box girder was revealed, and the propagation law of shock wave was clarified. Further researches on the distribution of overpressure on different parts of the box girder under different explosion conditions show that when the detonation core is located above the top of the box girder, the overpressure on the top surface of the box girder is larger; when the detonation core is located below the flange plate, the overpressure on the flange and web of the box girder is larger, and the overpressure on other parts is smaller. The blast center is located under the bottom plate of the box girder, and the flange, web and bottom plate of the box girder are subjected to large shock wave overpressure, and the full section of the structure is greatly affected by the explosion. Finally, based on the experimental and numerical analysis results, the equations of the peak overpressure on the top plate, web plate and bottom plate of the box girder under different working conditions were fitted, and the load model of the key parts of the box girder under different explosion conditions was established. © 2024 Chinese Vibration Engineering Society. All rights reserved.