# 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
\begin{table}
\begin{tabular}{c c c c} \hline  & \(k_{p2}\) & \(k_{G}\) \\ \hline \multirow{2}{*}{**Average**} & **Reliability** & \multirow{2}{*}{**Average**} & **Reliability** \\  & **Indicators** & & **Indicators** \\ \hline
1.00 & 11.1479 & 0.90 & 11.1846 \\
1.01 & 11.1500 & 0.95 & 11.1749 \\
1.02 & 11.1521 & 1.00 & 11.1652 \\
1.03 & 11.1542 & 1.05 & 11.1554 \\
1.04 & 11.1562 & 1.10 & 11.1457 \\
1.05 & 11.1582 & 1.15 & 11.1360 \\
1.06 & 11.1601 & 1.20 & 11.1262 \\
1.07 & 11.1620 & 1.25 & 11.1164 \\
1.08 & 11.1639 & 1.30 & 11.1066 \\
1.09 & 11.1657 & 1.35 & 11.0968 \\
1.10 & 11.1675 & 1.40 & 11.0870 \\ \hline \end{tabular}  
* Analysis of the influence of the strength reliability parameters of the main pier under combination II  
\end{table} 
Table 6: Effect of the average value of each parameter on the stability and reliability index under combination II. Figure 6: Effect of coefficient of variation of each parameter on stability and reliability index under combination II. As can be seen from Figure 7, the coefficient of variation for the concrete material's property uncertainty has the most drastic effect on the strength reliability index in this condition, followed by the uncertainty of the resistance calculation mode \(k_{p1}\) and the statistical parameter \(k_{G}\) of the constant load of the cast beam section, while the effects of \(v_{p}\) and \(k_{W}\) are relatively small. Table 7 demonstrates that under this combined working condition, the change in the mean value of each parameter has little impact on the strength reliability index, and no matter how the coefficient of each statistical parameter varies, the reliability index meets the requirements of the target reliability. From the above analysis, it is clear that for this bridge, the reliability of the piers during the cradle construction phase is controlled by the strength failure, and they are more dangerous during the maximum cantilever than when the last girder section is poured. To improve the reliability during the construction period, not only should more consideration be given to improving the structural resistance when designing the bridge but the self-weight error should also be strictly controlled during the construction period to ensure the safety of the bridge project. The construction distributed live load has less influence on the reliability of this bridge failure and thus can be considered less during construction. The variation of wind load parameters has a greater influence on the reliability of the maximum cantilever stage of this bridge, so cantilever cradle construction work should avoid being carried out in windy weather as much as possible. In addition, during the construction of continuous rigid bridges with hanging cradles, accidents involving a bridge collapse due to falling cradles have occurred. For the bridge in this example, if the hanging cradle falls, the reliability index becomes \(\beta_{1}=11.1585\), \(\beta_{2}=6.3056\), \(\beta_{3}=11.1611\), \(\beta_{4}=5.8423\) in order. As can be seen from Table 8, the hanging cradle fall has no effect on the stability reliability, but has some effect on the strength reliability, whereby \(\beta_{2}\) decreases by about \(6.08\%\) and \(\beta_{4}\) decreases by about \(6.11\%\). Figure 7: Effect of coefficient of variation of each parameter on strength reliability index under combination II.