## 2 Experimental Program
### Specimen Design and Properties  
The geometry and reinforcement configuration of the beams are presented in Figure 2. The cross-section of the beams was square with 150 mm sides, the length was 800 mm, and the free span 700 mm. The shear slenderness \(a/d=3.0\) implies a response dominated by static beam action, see, e.g., ref. [9]. The dimensionless constant \(\alpha=Al^{2}/I=261\) (\(l:h\approx 5:1\)) implies a significant effect of shear deformation on the static deflection mode, i.e., the first mode of vibration, as discussed in, e.g., ref. [10]. Here, \(a\) is the length of the shear span; \(d\) effective depth; \(A\) cross-section area; \(l\) length of the free span; \(l\) area moment of inertia; and \(h\) cross-section height. The beam may thus be classified as non-slender with a response dominated by beam action.  
The reinforcement design was determined from static design provisions using Eurocode 2 [11]. The spacing of the stirrups \(s\) was determined by fulfilling the maximum  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Specimen** & **\(\phi\) [mm]** & \(f_{y}\) [MPa] & \(f_{u}\) [MPa] \\ \hline \(\phi_{12,1}\) & 12 & 510 & 629 \\ \(\phi_{12,2}\) & 12 & 508 & 625 \\ \(\phi_{8,1}\) & 8 & 490 & 642 \\ \(\phi_{8,2}\) & 8 & 493 & 641 \\ \(\phi_{6,1}\) & 6 & 499 & 538 \\ \(\phi_{6,2}\) & 6 & 471 & 516 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Summary of results from tensile testing of the reinforcement used.  
Figure 1: Stress–strain curves measured from material testing of two samples of each reinforcement diameter.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Specimen** & **Age [days]** & \(f_{c,max}\) [MPa] & \(\mu\) [MPa] & \(\sigma\) [MPa] \\ \hline S1 & 30 & 43.03 & & \\ S2 & 30 & 39.97 & & \\ S3 & 30 & 45.36 & & \\ S4 & 30 & 44.76 & 39.53  & 8.48  \\ S5 & 30 & 41.98 & 42.32  & 3.38  \\ S6 & 30 & 41.45 & 42.32  \\ S7 & 30 & 36.09 & & \\ S8 & 30 & 19.65 & & \\ \hline \hline \end{tabular}
\end{table}
Table 3: Summary of the results from testing of the concrete strength.  
spacing from the design provisions, i.e., \(s\leq 0.75d\) for all beams. As shown in Table 4, the transverse reinforcement amount \(\rho_{w}=A_{s}/sb_{w}\) varied from 0% to 1.49% by altering the stirrup diameter with a constant spacing of 90 mm. The compressive strut inclination \(\theta\) determined from the calculations is also presented. The flexural tensile reinforcement was designed by determining the ratio \(\gamma=P_{\mathrm{\tiny{\circ}}}/P_{m}\), where \(P_{\mathrm{\tiny{\circ}}}\) is the maximum mid-span concentrated force the beam can sustain considering a shear failure mode and \(P_{m}\) the maximum load considering a flexural failure mode. The beams with the least amount of transverse reinforcement (types B and E) were designed for a ratio of \(\gamma\approx 1.0\). The longitudinal reinforcement amount that fulfilled this criterion was maintained, while increasing the shear reinforcement for types C and D so that an approximate transition zone from shear failure to flexural failure could be determined during static and dynamic loading. This resulted in a longitudinal reinforcement of \(\rho=A_{s}/bd\times 100=1.91\%\) as shown in Table 4, where all calculations are summarized. Beam types B-D were thus statically flexure-critical, as \(\gamma>1.0\). All beams except type A fulfil the requirement for minimum reinforcement in the design provisions. The overhang outside the supports was insufficient for the anchorage of the reinforcement, and mechanical anchorage was therefore provided by welding a steel plate on the protruding reinforcement, as shown in Figure 2.