## 1 Introduction
[10,11] fabricated a scaled model of a steel box girder to study the damage forms caused to a steel box girder under near-field explosive loading using an explosion test, and concluded that the peak overpressure and positive overpressure duration observed in the laboratory should not be used as testing and analyzing data; they then tested and analyzed the effects of various parameters of the explosion shock wave on a scaled model of steel box girder segments, and explored the relationship between the positive overpressure peak and the shock wave's duration and scaled distance, and the relationship between the peak overpressure and the shock wave's duration and scaled distance, as fitted to the peak overpressure; the results showed that the third-degree polynomial function was well fitted. [PERSON] et al. [12] identified the factors affecting the damage caused to a steel box girder by investigating its dynamic response under the effect of blast impact, as well as the relationship between the structural model parameters and the scaled distance of the explosives. [PERSON] et al. [13] conducted a study on the dynamic response of miniaturized steel box girder sections under proximity blasts, explored the link between the damage patterns of steel box girder members under blast loading and their modeling parameters and explosive types, and also gained insights into some of the damage qualities of the steel box girder and the reinforced concrete main tower. Based on the fluid-solid coupling method, [PERSON] et al. [14] concluded that the damage caused to steel box girder bridges is mainly divided into three stages under the action of a blast load, and longitudinal and transverse partitions can significantly improve the blast resistance of steel box girder bridges. By using LS-DYNA 2023R1 software for numerical simulation, [PERSON] et al. [15] calculated the value of blast shock wave overpressure based on previously proposed empirical equations, thus investigating the damage characteristics of steel truss structures under blast loading. [PERSON] et al. [16] revealed the importance of the top design scheme for energy consumption through calculations, and [PERSON] et al. [17] further investigated the structural damage patterns caused by explosions in steel box girders with the help of the LS-DYNA fluid-solid coupling technique, emphasizing the necessity of increasing the blast protection layer in steel box girders. [PERSON] et al. [18] found that the incident angle of the shock wave affected the damage pattern of steel box girders, and the degree of destruction was related to the intensity of the shock wave. [PERSON] et al. [19] proposed a damage assessment method for pre-stressed continuous box girder bridges. [PERSON] et al. [20] showed that severe eccentric explosive loading on bridge decks can cause damage to steel box girders, making the bridge virtually unrepairable. Due to the advantages of its superior structural torsion resistance, rapid construction process, and lower impact of traffic disturbance, the application proportion of steel box girder bridges in highway bridges is increasing. Therefore, it is of great theoretical and practical significance to explore the damage characteristics of steel box girders when they are subjected to explosive shock waves, in order to improve the explosion-proof design of bridges. However, most existing studies have only conducted experimental or numerical simulations, and there is a lack of experimental verification of the simulation results; there is even less emphasis on the role of partitions and stiffening ribs in the process of anti-explosive research, and there is also a lack of quantitative analysis. In this study, finite element modeling of a steel box model was carried out with numerical simulation, based on the S-ALE fluid-structure coupling method, using LS-DYNA software, and the damage caused to a steel box girder under an explosion load was simulated on the basis of model validation.