###### Abstract
[15] compared the mechanical performances of U-steel supports and concrete-filled steel tubular supports by theoretical calculation and numerical simulation. At present, the application fields of steel brackets are more extensive, such as underground mine working and supporting roadways, but there is a lack of research on the application of steel support systems in the process of bridge reconstruction. In the field of bridge reconstruction, there are numerous studies on the major methods and stability analysis during the procedure of bridge rebuilding and construction. [PERSON] et al. [16] adopted the Analytic Hierarchy Process (AHP) method to analyze the multi-source data and set the early warning threshold for bridge safety in construction based on the multi-source data of nearby construction and demolition construction of a large-span RC arch bridge in China. [PERSON] et al. [17] considered a new type of corrosion-resistant steel, A709-50 CR, for girder replacement. The reliability- and risk-based bi-objective optimizations were conducted on a multi-girder carbon steel bridge to determine when and which carbon steel girders should be replaced under different target performance indicators. [PERSON] et al. [18] investigated the effects of different alternatives for superstructure and substructure systems on the progressive collapse procedure after verifying the bridge collapse procedure. In addition, the application of restrainers at the connection of the deck to the abutment was studied as an effective solution in order to prevent collapse propagation and minimize associated damages. [PERSON] et al. [19] performed an experimental investigation to systematically determine the seismic performance of mechanically spliced bridge columns and to develop the most comprehensive test database for these columns. [PERSON] et al. [20] investigated the effects of the earthquakes' duration, intensity, and magnitude on the seismic response of reinforced concrete bridges retrofitted with seismic bearings. Based on the deformation coordination principle and suspension cable theory, [PERSON] et al. [21] proposed a practical calculation method that can calculate the load of the tower acting by a cable system in the cable lifting construction of arch bridges, to calculate and analyze cable lifting construction more quickly and accurately. Moreover, a large-span arch bridge under construction was used as a case study, and the correctness of the calculation method was verified by measuring the displacements of the tower top. [PERSON] et al. [22] proposed using the Copula function to calculate the reliability index of the bridge structure construction process system. The basic theory of the Copula function was introduced in detail, and the formula was improved according to the actual situation on the force of the existing railway bridge girder, which can minimize the disturbance to the ballast bed and reduce the line-blocking time. However, the deformation and stress of the steel support structure under load still need to be further studied to determine the safety and stability of this construction scheme. Accordingly, a numerical simulation of the superstructure and support system model is carried out in this paper based on the actual bridge reconstruction project. Based on the established model, the force and deformation of the temporary support system under the trainload, as well as the deformation of the bridge and track components supported by this system, are investigated. The safety and stability of the construction critical process are analyzed considering the bearing capacity, stability, deflection of the steel brace, and the bearing capacity of the braced steel pipe pile. In addition, the problems and solutions in the actual construction case are introduced, which can provide a reference for the related projects.