*4.1. Extended Parameter Analysis*

## 4.1.1. Numerical Model

Numerical simulations were performed using ABAQUS and the numerical model was simplified as follows:


According to the above points, the finite element numerical model was established, as shown in Figure 12. Due to the difference between the simulated constitutive relationship and the actual constitutive relationship of the materials, as well as the influence of interface simulation and loading error on the test, the numerical model needed to be continuously adjusted according to the test results. The numerical model was adjusted with the peak load and load–displacement curve of actual specimens P1 and S1-S as the control index. By adjusting the constitutive relationship of the material, interface parameters, and loading system in the numerical model, the load–displacement curves of the specimen recorded in the tests and the numerical model were obtained, as shown in Figure 13. It can be seen that the load–displacement curves of specimens P1 and S1-S recorded in the tests were basically consistent with those recorded by the numerical model. The difference between peak loads was less than 5%, indicating that the numerical model was well in accordance with the specimens, meaning it could be used as the basic model for the extended parameter analyses.

**Figure 12.** Finite element model. (**a**) Model of specimen P1; (**b**) Model of specimen S1-S.

#### 4.1.2. Parameter Extended Analysis

The influencing parameters of the axial compression bearing capacity for the strengthened specimens included the thickness and strength of the SSAWC, self-stress, and the thickness and concrete strength of the LCSS. The influence of the cross-sectional area of the filled concrete on the bearing capacity was considered in accordance with the code in [24]. Due to the limitations of the prefabricated mold used for the segments, the cross-sectional area of the LCSS basically remained invariable. Therefore, the influencing parameters were mainly self-stress, the strength of the SSAWC, and the concrete strength of the LCSS. Among them, the strength of filled concrete was set to three grades: C35, C40, C50; the longitudinal stress values were set to 0.8 MPa, 1.0 MPa, and 1.2 MPa; and the concrete strength of the LCSS was set to three grades: C35, C40, C50. As such, 9 extended numerical models were built to study the influence of these parameters, with Table 8 showing the specific parameter settings and peak loads.


**Table 8.** Material parameters of the extended models.

