## 3 Equivalent Conversion of the Cross-Section  
Several investigations focused on bridges with corrugated steel webs. [PERSON] et al. [19] investigated the buckling strength of corrugated steel webs. [PERSON] et al. [20] investigated the flexural performance of composite girder bridges with corrugated steel webs. [PERSON] et al. [21] conducted an experimental study on the shear performance of bridges with corrugated steel webs. In these investigations, finite element analysis of the bridges simulated by solid elements was performed; however, the whole calculating process is not very efficient. Instead, relevant researchers proposed some equivalent calculation methods for bridges with corrugated steel webs. [PERSON] et al. [22] simplified three-dimensional corrugated steel webs into two-dimensional models through the methods of stiffness equivalence and displacement equivalence. [PERSON] et al. [23] simplified the three-dimensional corrugated steel web into a two-dimensional model through the longitudinal equivalent stiffness. [PERSON] et al. [24] simplified three-dimensional corrugated steel webs into two-dimensional webs through stiffness equivalence and carried out static analysis. [PERSON] et al. [25] simplified the three-dimensional corrugated steel web into concrete web by integrating the theory of equal weight and equal stiffness. In general, in the current research, a method for replacing the corrugated steel web with equivalent concrete was proposed. Subsequently, the sensitivity of structural parameters in the construction stage was analyzed. The beam model simplifies the three-dimensional structure into a one-dimensional model, and the deflection equation of the beam can be obtained by assuming that the fibers on each section of the beam remain in a straight line when bending and deforming. In practical applications, the boundary conditions can be determined according to the specific conditions, such as beam support conditions and boundary fixed conditions, and then the equation can be solved by a numerical solution or analytical solution to obtain the deflection distribution of the corrugated steel web under the action of external loads [26; 27]. It should be noted that the above modeling process is based on the assumptions of Euler-Bernoulli beam theory. If the effects of shear deformation and moment of inertia need to be considered, the Timoshenko beam theory or Reddy beam theory can be used for analysis and modeling [28; 29]. The cross-section of the composite beam with corrugated steel web is composed of steel and concrete. To improve the efficiency of finite element modeling without reducing the accuracy, it is necessary to convert the composite beam with the corrugated steel web into a section composed of the same material. The basic principle of the conversion process is to keep four parameters unchanged, i.e., the resultant force before and after the conversion, the height of the centroid (i.e., the position of the resultant force), the overall dead weight of the box girder, and the strain coordination condition. The labels \(E_{c}\), \(A_{c}\), \(\varepsilon_{c}\), and \(\sigma_{c}\) represent the elastic modulus of concrete, the cross-section area, strain, and stress, respectively. The labels \(E_{s}\), \(A_{s}\), \(\varepsilon_{s}\), and \(\sigma_{s}\) represent the elastic modulus of steel, the cross-section area, strain, and stress, respectively. \(A_{sc}\) represents the area of the concrete section converted from the steel section. Figure 2: Actual scene of the north approach bridge.