# Real Cyclic Load-Bearing Test of a Ceramic-Reinforced Slab
## 2 Description of the Analyzed Slab
### Estimation of the Theoretical Load-Bearing Capacity  
By considering a total of 4 ribs per meter according to the typical cross section in Figure 2, a minimum of 12 bars of 5 mm diameter per meter was considered in the lower section of the mid-span areas, while no bars were assumed within the upper part (only concrete); this corresponds to a typical distribution of reinforcements against positive bending moments (those appearing at mid-span areas). On the contrary, in supporting areas, there were 12 reinforcing bars in upper levels without any in the lower section. By using the approximation proposed by [PERSON] [4] in the ITEC manual to  
Figure 5: Reinforcements are inclined so as to maximize their performance against shear. Figure 6: Stress–strain curves obtained from the tensile test on the extracted sample (first and second cycles). determine the load-bearing strength of ceramic-reinforced slabs, it is possible to estimate the ultimate load-bearing capacity. In order to calculate the ultimate bending moment capacity, we firstly need the position of the neutral axis under positive (mid-span areas) and negative (supporting areas) bending moments. This may be obtained by starting with the total capacity of reinforcements:  
\[F_{t1}=12\;\text{\emph{rebars}}\cdot 19.62\;\text{mm}^{2}\cdot 413\;\text{MPa}=97.2 \;\text{kN}. \tag{3}\]  
The position of the neutral axis in the case of positive bending may be estimated by equating the total area of concrete which is needed in the upper layer with the maximum tensile capacity of reinforcing bars:  
\[F_{c1}=F_{t1}\to h_{FN+}\cdot 1000\;\text{mm}\cdot 15\;\text{MPa}=97.200\; \text{N}, \tag{4}\]  
Thus, the position of the neutral axis almost coincides with the upper layer of the slab, so the distance \"\(d\)\" is  
\[d=230\;\text{mm}-6.48-25=198.52\;\text{mm} \tag{5}\]  
and the final resisted positive bending moment is  
\[M_{Rd+}=F_{t1}\cdot d=97.2\;\text{kN}\cdot 0.198\;\text{m}=19.24\;\text{kNm}. \tag{6}\]  
On the contrary, in the case of supporting areas, the tensile force appears in upper layers and it is the concrete of the ribs in the lower levels which resists compression stresses. These ribs sum to a total width of 60 cm (15 cm per ceramic piece, and four pieces per meter). Then, the neutral axis is  
\[ \begin{array}{c}F_{c1}=F_{t1}\to h_{FN-}600\;\text{mm}\cdot 15\;\text{MPa}=97.200\;\text{N},\\ h_{FN-}=10.80\;\text{mm}.\end{array}  \tag{7}\]  
The distance \"\(d\)\" is 194.2 mm, and the ultimate resisted bending moment is slightly lower in this case:  
\[M_{Rd-}=F_{t1}\cdot d=97.2\;\text{kN}\cdot 0.194\;\text{m}=18.85\;\text{kNm}. \tag{8}\]  
Regarding the load-bearing capacity, it is evident that the contribution of concrete is very low. Thus, by assuming the span of the tested slab, and due to the hypothesis of continuity on both supporting edges thanks to the previous shoring of the steel structure, the maximum theoretical uniform load that could be resisted by this particular ceramic-reinforced slab (obviously considering only the bending moment) would be  
\[M_{Rd-}=q\cdot\frac{L^{2}}{12}\to q=M_{Rd-}\cdot\frac{12}{L^{2}}=18.85\; \text{kNm}\cdot\frac{12}{4.80^{2}}=\;9.81\;\text{kN}/\text{m}^{2}. \tag{9}\]  
The performance of a flat slab (especially with short span) is not only characterized by the bending strength; we obviously need to also consider the shear resistance. By again following the expressions proposed by [PERSON] [4], the total capacity against shear of a ceramic-reinforced slab would be  
\[V_{Rd}=0.3\;\text{MPa}\cdot 200\;\text{mm}\cdot 194\;\text{mm}=11.64\;\text{ kN}/\text{mL}. \tag{10}\]  
This value is relatively low compared with usual acting shear forces, especially compared with the bending capacity of the same slabs; this is the reason why there are bars inclined at 45\({}^{\circ}\) in the principal ribs of the section (see Figure 5), to enhance the shear response of the section.