## 4 Conclusions  
The flexural behavior of a modular specimen with a joint was analyzed quantitatively according to estimation of the steel reinforcement strain and was compared with that of an integral specimen. 1. The load-deflection behavior of the modular and integral specimens was very similar. However, the crack progression and failure patterns differed owing to the joint of the modular specimen. The first crack of the modular specimen occurred at the discontinuity interface, and the maximum crack width was 327% larger than that of the integral specimen. 2. Regarding the steel reinforcement strain measured at the loading point, the strain of the integral specimen increased sharply after the yield load was reached, but that of the modular specimen did not exhibit any change. 3. In the case of the strain estimated according to the crack width, all the estimated strains of the modular specimen were greater than those of the integral specimens, and the gap of the strains  
Figure 8: Strain change for each load stage: (**a**) measured strain; (**b**) estimated strain by EC2 Part.1-1. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Base Type**} & \multicolumn{3}{c}{**Estimated Strain at Service Load**} & \multicolumn{3}{c}{**Estimated Strain at Yield Load**} & \multicolumn{3}{c}{**Estimated Strain at ultimate load**} \\  & \multicolumn{3}{c}{(x10\({}^{-6}\) mm/mm)} & \multicolumn{3}{c}{(x10\({}^{-6}\) mm/mm)} & \multicolumn{3}{c}{(x10\({}^{-6}\) mm/mm)} \\ \cline{2-9}  & **Integral\({}^{1}\)** & **Modular\({}^{2}\)** & **Ratio** & **Integral\({}^{1}\)** & **Modular\({}^{2}\)** & **Ratio** & **Integral\({}^{1}\)** & **Modular\({}^{2}\)** & **Ratio** \\  & \((\alpha_{s}^{\prime})^{1}\) & \((\alpha_{s}^{\prime})^{2}\) & \((\alpha_{s}^{\prime})^{1}\) & \((\alpha_{s}^{\prime})^{1}\) & \((\alpha_{s}^{\prime})^{1}\) & \((\alpha_{s}^{\prime})^{1}\) & \((\alpha_{s}^{\prime})^{1}\) & \((\alpha_{s}^{\prime})^{1}\) & \((\alpha_{s}^{\prime})^{1}\) \\ \hline EC2 part.1-1 & 1527.14 & 1143.95 & 0.749 & 1676.33 & 1666.07 & 0.994 & 1974.72 & 3008.76 & 1.524 \\ EC2 part.2 & 1544.78 & 1186.65 & 0.768 & 1699.55 & 1728.28 & 1.017 & 2009.07 & 3121.1 & 1.554 \\ Euro-Design & 1240.66 & 1427.49 & 1.151 & 1426.84 & 2079.09 & 1.457 & 1799.2 & 3754.68 & 2.087 \\ Handbook & 1437.53 & 1252.70 & 0.871 & 1600.91 & 1824.48 & 1.140 & 1927.66 & 3294.85 & 1.709 \\ \hline \hline \end{tabular}  
* Strain was obtained using the first-order formula. \({}^{2}\) Strain was obtained using the second-order formula.  
\end{table} 
Table 8: Comparison of the estimated strain changes for each load stage. increased with the increasing load. Therefore, if the same load is applied, the steel reinforcement yield at a discontinuity in the modular specimen occurs earlier than that in the integral specimen. 4. At the yield load stage, the strain estimated using the first-order formula reflected the behavior of the integral specimen, and that estimated using the second-order formula reflected the behavior of the modular specimen. Comparing the results obtained using the different formulas revealed that the estimated strain at the service load was lower for the modular specimen than for the integral specimen. However, at the yield and ultimate load stages, the estimated strain of the modular specimen increased rapidly and the strain gap was widened. The measured strain exhibited the opposite result. Therefore, in the modular specimen, only the steel reinforcement at the discontinuity interface of the joint resisted the load, whereas in the integral specimen, the steel reinforcement uniformly resisted the load in the central section, where a constant moment occurred. It was determined that in the modular specimen, only the steel reinforcement at the discontinuity interface resisted the load. Thus, the steel reinforcement of a modular structure is likely to yield earlier than that of an integral structure. Hence, the safety and quality of the connecting steel reinforcement should be considered in design and construction.