# Structural Behavior of Large-Scale I-Beams with Combined Textile and CFRP Reinforcement
## 2 Experimental Investigation: Materials and Methods
### Cross-Section and Reinforcement Layout  
The dimensions of the cross-section of beams FT01-FT03 (Figure 5) were chosen based on an preliminary design using sectional analysis and a conventional finite-element program [61] designed for steel-reinforced concrete utilizing adapted material parameters. The main design criteria were:  
* To investigate the bending behavior at ultimate limit state, especially
* Rupture of tensile reinforcement (FT01)
* Flexural failure of concrete compressive zone (FT02)
* The behavior of a zone with full rebar splice (FT03)
* To prevent unintended failure, e.g., in shear, in anchorage, or in deformation induced failure (for example in lateral failure of the compression chord or in local failure of the web)
* To evaluate sufficient announcement of failure between SLS, defined by the limits of deflection, and ULS for bending \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Test No.** & **Age** & \(f_{\text{cm,cube}}\) & \(f_{\text{cm,cyl}}\) & \(f_{\text{ct,sp}}\) & \(f_{\text{cm,pris}}\) & \(f_{\text{ctm,fl}}\) & \(E_{\text{cm}}\) & \(\varepsilon_{\text{c1}}\) \\ \hline  & **[d]** & **[MPa]** & **[MPa]** & **[MPa]** & **[MPa]** & **[MPa]** & **[MPa]** & **[MPa]** & **[\%o]** \\ \hline FT01 & 28 & 112.7 & 98.8 & 5.58 & 95.75 & 12.29 & 38,750 & 2.69 \\ FT02 & 22 & 111.0 & -* & 5.25 & 94.96 & 13.42 & 39,890 & -* \\ FT03 & 30 & 104.6 & 97.0 & 4.77 & 97.01 & 13.23 & 40,620 & 2.65 \\ \hline \hline \end{tabular}  
* For numerical calculation, \(f_{\text{cm,cyl}}\) was converted with the factor 1/1.11 from \(f_{\text{cm,cube}}\) (Mean conversion of FT01 and FT02) to \(f_{\text{cm,cyl}}\) = 100.0 MPa. The mean value of \(\varepsilon_{\text{c1}}\) = 2.67\(\%_{\text{o}}\) was chosen for calculation of FT02.  
\end{table} 
Table 4: Material properties of hardened concrete at the day of testing. The slenderness of \(l/l_{h}=700/90=7.8\) resulted from full utilization of the non-prestressed carbon rebars at ULS and complying with SLS requirements for FT01, i.e., deflection limit. No prechamber was chosen for the beams. The width of 200 mm for the tension flanges was necessary to place 20 bars of FT02 with adequate spacing. The same width was chosen for the compression flange to increase lateral stiffness. The depth of 150 mm of the tension and compression chords ensured anchorage of the planar shear reinforcement (see e.g., [39] for determination of the full anchorage length in warp direction of 78 mm for a comparable cementitious matrix). However, the compression chord depth for FT02 was reduced in mid-span to diminish the resistance of the compression zone in order to provoke flexural compression failure of concrete. A web width of 50 mm allowed for concreting the beams in upright position with 4 layers of shear reinforcement for FT02. A minimum concrete cover of 10 mm was chosen in the web based on previous experience from uniaxial tensile tests [62]. Previous studies on tensile specimen reinforced with the same carbon rebar indicated that a cover of 25 mm is necessary in the tension zone to transfer bond forces [40] without premature longitudinal cracking and concrete  
Figure 3: Test setup with continuous loading and instrumentation. spalling. The same cover was chosen for the grid in the compression flange. As shown in Figure 5 (left), preformed grids in compression (CFRP grid) and tension flange (GFRP grid) were chosen to take the tension forces resulting from lateral connection of the outlying rebar and concrete areas. The profiles were open to the center of the beam, allowing the primary shear reinforcement to penetrate and securely anchor in the flange. To close the open profiles and to increase the resistance in lateral direction, short carbon bars from the same material as the main rebars were added (see Figure 6). AR-glass fabrics were chosen specifically for the tension flange for their higher ultimate strain (Table 1) to prevent premature rupture of the longitudinal yarns and spalling of the concrete.