# A Durability Prediction Method for Historical Square Rebar Reinforced Concrete Buildings
## 5 Applications of the Proposed Method
### The Durability Prediction Results of the Two Buildings  
According to the surrounding environments of the buildings and the working conditions of the critical components, the values of \(Kco_{2}\), \(K_{kl}\), \(K_{kt}\), \(K_{ks}\), \(RH\), \(T\), and \(K_{cl}\) can be determined [18], and correspondingly critical components' concrete strength and the cover depth were measured especially. Subsequently, the durability prediction times of the two buildings were calculated respectively. The calculation methods of corrosion-induced cracking life for the single concrete component were compared with the calculation methods from GB/T 51,355 standard. The results from the different methods are listed in Table 4.  
In terms of the total durability prediction for the single component, the results obtained using the proposed method were relatively close to the results from the China standard; yet, the Part 1 time and the Part 2 time were correspondingly different between these two calculation methods, respectively. As considering the compared results, the carbonization-resist ability of the historical concrete is weaker than the modern concrete. In contrast, for the time from corrosion initiation to concrete cracking, the square rebar components were longer than the round rebar components. The combinations of these two parts resulted in comparable outcomes from the two different calculation methods, which were coincidences. It should be noted that GB/T 51,355 is an inapplicable standard for square rebar components since it is based on experiments for round rebar components due to the calculation equation for the critical depth of corrosion of rebar and the material properties tests for modern concrete. The improvement of the proposed calculation method is not related only relatively more accuracy ensured than GB/T 51,355 for durability prediction, but also it depends on realistic tests for the historical concretes and the experiments for square rebar components. The following subsection will analyze the reliability and applicability of the proposed method.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Names**} & **Durability Assessment** & \(c\) & \(f_{ave}\) & \(d^{\prime}\) & \multicolumn{3}{c}{**Durability Prediction by**} & \multicolumn{3}{c}{**Durability Prediction by the**} \\  & **Assessment** & **/mm** & **/MPa** & **/mm** & **GB/T 51,355/Vears** & \multicolumn{3}{c}{**Proposed Method/Vears**} \\ \cline{4-11}  & **Time/Years** & & & & * **Part 1** & *** **Part 2** & **Total** & * **Part 1** & *** **Part 2** & **Total** \\ \hline Songfengge Building & 86 & 34 & 22.5 & 24 & 47 & 53 & 100 & 43 & 60 & 103 \\ Main Hall of the Tomb of Yu & 78 & 40 & 15.7 & 25 & 49 & 25 & 74 & 46 & 30 & 76 \\ \hline \multicolumn{11}{l}{* Part 1 and Part 2 corresponded to the time before rebar corrosion and the time from corrosion initiation to concrete cover cracking in} \\ \multicolumn{11}{l}{Sections 4.1 and 4.2, respectively.} \\ \end{tabular}
\end{table}
Table 4: The predicted durability lives from different calculation methods for the two buildings.  
Figure 11: (**a**) The results of component importance analysis for the Main Hall of the Tomb of Yu; (**b**) the critical components of the Main Hall of the Tomb of Yu.