To improve the anti-cracking performance of the negative bending moment zone of the continuous prefabricated beam bridge, this paper proposed a UHPC-NC (normal concrete) structure with a high reinforcement ratio (larger than 1.5%) in the negative bending moment zone of an assembly continuous beam bridge. Taking A PC continuous beam bridge on the Nanchang to Jiujiang expressway as the engineering prototype, the study carried out the scale model tests with the scale ratio of 1.4 in the transverse direction and 1.5 in the longitudinal direction. Then, based on the "plane section" assumption, it developed the calculation methods formula of the cracking moment for the connection structure under different bearing modes. The influences of the thickness of the UHPC layer and reinforcement ratio on the cracking moment were analyzed by means of the finite element method. The results show that the cracking moment with the UHPC layer in the negative moment zone of the continuous girder bridge is improved significantly. The feasibility of the connection structure and the validity of the finite element model were verified and the calculation method of cracking moment in this paper is reliable and can provide reference for design and engineering application. the relative error of the reinforcement ratio between the finite element method and the method in this paper is within 10%. Under the action of pure moment and bending shear combination, the cracking moment of UHPC-NC structure increases with the increase of UHPC layer thickness and reinforcement ratio.

To explore the destructive forms of bridge damage caused by explosions of hazardous materials in vehicles and the distribution of explosion load pressures on the bridge deck, a refined numerical model was established using AUTODYN software. The study analyzed the regional distribution characteristics of the bridge load pressure field under various explosion conditions with different shapes and sizes of steel plates, and determined the critical dimensions at which the steel plates play a blocking role against shock waves. In response to the challenges of conducting bridge explosion experiments, which involve high risks and large expenses, the research referred to a detailed inspection report of a real bridge after an explosion accident and inferred its explosion damage process. Based on the least squares method, a polynomial curve fitting was applied to numerous of numerical calculation results, and the traditional calculation formula for explosion shock wave pressure in the free air domain was modified. A prediction formula for the peak overpressure on the bridge deck under the explosive effects from the vehicle-borne cargo, taking into account the blocking of carriage steel plates, was proposed. The load pressure distribution calculated by this formula corresponded well to the damaged areas on the bridge deck as reported in the real bridge inspection report.