# Experimental Study on an Optimized-Section Precast Slab with Structural Aesthetics
## 3 Test Results and Discussion
### Comparison of the Test and Analysis Results  
To determine if the OPS member design can be properly done in accordance with the current standards, flexural and shear performance evaluation of the OPS was performed by applying the ACI318-14 [16] and KCI 2012 [17] code equations, as shown in Table 3. In addition to these code equations, layered sectional analysis (LSA) [18; 19] considering the strain compatibility and force equilibrium conditions was performed for the evaluation of flexural strength. For the shear strength evaluation, a detailed comparative analysis of the test and the analysis results was conducted using RESPONSE2000 (R2K) [20], a program that was developed at the University of Toronto that is based on the shear analysis model MCFT [21; 22; 23]. Since horizontal shear cracks at the interface between the PC unit and the topping concrete did not occur in any of the composite specimens, the interface was considered as a full-composite interface when the layered sectional analysis was performed. In addition, the compressive strengths of the topping concrete, rather than those of the PC unit, were applied as in practical design when the shear strengths were calculated for the composite PC specimens. Figure 14: Measured strains from the longitudinal and shear reinforcements. \begin{table}
\begin{tabular}{c c} \hline
**Type** & **Code Equation \({}^{*}\)** \\ \hline Flexural strength & \(M_{a}=A_{p}f_{p}(d_{p}-\frac{q}{4})+A_{s}f_{p}(d-\frac{q}{4})+A_{s}^{\prime}f _{p}(\frac{q}{4}-d^{\prime})\) \\ \hline Shear strength & \(V_{Av}=(0.29\sqrt{f_{A}}+0.3f_{p})b_{ad_{p}}\) (contribution of concrete) \\  & \(V_{s}=\frac{A_{s}d}{s}(\sin\alpha\,\epsilon\,\beta+\cos\alpha)\) (contribution of string) \\ \hline \end{tabular} \({}^{*}\) Note: \(A_{p}=\) the sectional area of the prestressing strands (mm\({}^{2}\)); \(A_{s}=\) the sectional area of the tension reinforcement (mm\({}^{2}\)); \(A_{s}=\) the sectional area of the compression reinforcement (mm\({}^{2}\)); \(A_{s}=\) the sectional area of the stirrup (mm\({}^{2}\)); \(a=\) the depth of the equivalent rectangular stress block (mm); \(b_{w}=\) the web width (mm); \(d_{p}=\) the depth of the prestressing strands (mm); \(d_{s}=\) the depth of the tension reinforcement (mm); \(f_{w}=\) the stress in the prestressing strands at nominal flexural strength (MPa); \(f_{d}=\) the compressive strength of the concrete (MPa); \(f_{w}=\) the compressive stress at the control of the cross section after pressures release (MPa); \(s=\) the stirrup spacing (mm); \(a=\) the angle of the inclined sturrup (radi); \(\beta=\) the angle of the inclined critical crack (rad).  
\end{table} 
Table 3: Code equations for estimating the flexural and shear strength of the OPS [6; 7]. Table 4 and Figure 15 show the comparison of the test and the analysis results with respect to the flexural and shear strengths of the specimens. Figure 15a shows the strength evaluation results of the UF and CF flexural specimens. LSA showed a very accurate evaluation of the flexural strength of the UF specimen, however it somewhat overestimated the flexural strength of the CF specimen. It seems that the CF specimen reached failure at a lower load because the loading was somehow concentrated at one of the two loading points, as shown in Figure 10c. However, the nominal moment capacity (\(M_{n}\)) that was calculated using the design equation very accurately evaluated the flexural capacity of the UF and CF members and thus, it was confirmed that when the member is designed with the strength reduction factor (\(\phi\)) of 0.90 [16], sufficient flexural strength can be secured.