# Reliability Analysis of the Main Pier during the Construction Period of HLCR Bridges
## 3 Reliability Analysis of the Main Pier of an HLCR Bridge with a Cradle Construction
### Project Examples
#### 3.3.4 Reliability Parameter Impact Analysis  
1. Analysis of the influence of the stability and reliability parameters of the main pier under combination I  
Analysis of Figure 4 shows that under this combination, if the coefficient of variation of design variables is higher, the reliability of the structure is lower. Therefore, trying to reduce the variability of the calculation model, materials and loads can improve the reliability of the structure. In addition, it can be seen from the figure that variation of the coefficient of uncertainty \(k_{p2}\) for the force-resisting calculation model has the greatest influence on the reliability, followed by the statistical parameter \(k_{G}\) of the structural self-weight. Meanwhile, the variation of the unbalanced parameter \(v_{p}^{\prime}\) of the casting speed of the beam section and the coefficient of variation of the construction live load \(k_{Q}\) have barely any influence on the reliability of the structure. This indicates that the structural reliability of the bridge constructed by hanging baskets in this combination should be analyzed with the most accurate selection of a resistance calculation model possible, and the control of the construction distributed live load and the synchronous casting speed of the last girder section have little significance for the structural stability and reliability. We can see from Table 4 that under this combined working condition, the change in the mean value of each parameter has little impact on the stability and reliability index. Figure 4: Effect of coefficient of variation of each parameter on stability reliability index under combination I. 2. Analysis of the influence of reliability parameters on the strength of the main pier under combination II  
The analysis in Figure 5 shows that the strength reliability decreases with an increase in the coefficient of variation of statistical parameters in this combined condition. Therefore, to improve the strength reliability of this combined structure, variability of the calculation mode, construction material and load deviation should be reduced as much as possible. The variation of the statistical parameter \(k_{mh}\) of concrete strength has the greatest influence on the reliability index of the structure, followed by the variation coefficient \(k_{p1}\) of the resistance calculation mode, the statistical parameter \(k_{G}\) of self-weight, the coefficient \(v_{p}^{\prime}\) for imbalance of the block casting and the coefficient \(v_{p}\) for deviation of the cast blocks. The variation of the statistical parameter \(k_{Q}\) and the deviation coefficient \(v_{Q}\) of the construction live load has barely any effect on the structural strength reliability index. This means that to improve the reliability of the structural strength under such combined conditions, it is necessary to strictly control the strength of the concrete materials and the self-weight of the blocks. We can see from Table 5 that under this working condition, the change to the mean value of each parameter has little impact on the strength reliability index. The difference in reliability index between simultaneous pouring at both ends and pouring at one end before pouring at the other end is not significant, and both approaches meet the requirement of a reliability index measuring 5.