# Shear Behavior of Superposed Perfobond Connectors Considering Lateral Constraints
## 2 Experimental Program  
### Push-Out Specimens  
In this study, 12 superposed perfobond connectors were designed for push-out testing according to Eurocode 4 [28]. All the specimens were made of Q355 H-shaped steel and HRB400 ribbed bar. The specific parameters are shown in Table 1. Figure 3 shows a schematic diagram of the specimen; the height \(H\), width \(W\), and thickness \(T\) of the concrete slab were 600, 500 and 150 mm, respectively. The H-section specification was HW250 \(\times\) 250 \(\times\) 9 \(\times\) 14. The height \(h\), length \(B\) and thickness \(t\) of the perfobond rib were 100, 350 and 16 mm, respectively. \(C_{\mathrm{u}}\) and \(C_{\mathrm{b}}\) were the thickness of the concrete wrap at the top and side of the perfobond rib, which were all 50 mm. The main design parameters included the lateral constraints and hole areas of the perfobond rib. The lateral constraints were mainly affected by the concrete compressive strength, diameter of the perforating rebar, and the number of transverse reinforcements. The hole area was changed by varying the hole's diameter and shape. The design specifications of the perfobond rib are shown in Figure 4 and Table 1, thereinto, \(d\), \(d_{\mathrm{l}}\), \(d_{\mathrm{h}}\) and \(A\) were the holes' diameter, length, height, and the areas of the perfobond rib, and \(l\) was the distance between the holes. \(d_{\mathrm{s}}\) was the diameter of the perforating rebar. The transverse reinforcement number was varied via the stirrup forms of the concrete, which included both conventional (see Figure 3c) and segmental (see Figure 3d) stirrup constraints.  
Figure 3: Structural diagrams of push-out specimens (units: mm): (**a**) Front view; (**b**) Section 1-1; (**c**) Section 2-2 (conventional stirrups); (**d**) Section 2-2 (segmented stirrups).  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Specimen** & **Hole Shape** & \begin{tabular}{c} **Number of** \\ **Holes** \(n\) \\ \end{tabular} & \begin{tabular}{c} **\(d\) (mm)** \\ \end{tabular} & \begin{tabular}{c} **\(d_{1}\) (mm)** \\ \end{tabular} & \begin{tabular}{c} **\(d_{h}\) mm** \\ \end{tabular} & \begin{tabular}{c} **\(A\)** \\ **(mm\({}^{2}\))** \\ \end{tabular} & \
\begin{tabular}{c} **\(l\) (mm)** \\ \end{tabular} &
\begin{tabular}{c} **\(d_{s}\)** \\ **Grade** \\ \end{tabular} & **Stirrups Form** \\ \hline P-1 & & 2 & 50 & 50 & 50 & 1963.5 & 120 & 16 & C60 \\ P-2 & & 2 & 50 & 50 & 50 & 1963.5 & 120 & 20 & C60 \\ P-3 & & 2 & 50 & 50 & 50 & 1963.5 & 120 & 0 & C60 \\ P-4 & Circular & 1 & 50 & 50 & 50 & 1963.5 & 0 & 16 & C60 \\ P-5 & hole & 2 & 60 & 60 & 60 & 2827.4 & 120 & 16 & C60 \\ CP-1 & & 2 & 50 & 50 & 50 & 1963.5 & 120 & 20 & C40 & stirrups \\ CP-2 & & 2 & 50 & 50 & 50 & 1963.5 & 120 & 16 & C40 & \\ CP-3 & & 2 & 50 & 50 & 50 & 1963.5 & 120 & 0 & C40 & \\ \hline LP-1 & Long hole & 2 & 50 & 70 & 50 & 2963.5 & 120 & 16 & C60 & \\ HP-1 & High hole & 2 & 50 & 50 & 70 & 2963.5 & 120 & 16 & C60 & \\ \hline NP-1 & Circular & 2 & 50 & 50 & 50 & 1963.5 & 120 & 16 & C60 & None \\ SP-1 & hole & 2 & 50 & 50 & 50 & 1963.5 & 120 & 16 & C60 & Segmented stirrups \\ \hline \hline \end{tabular}
\end{table}
Table 1: Parameters of push-out specimens.  
Lubricating oil was applied to the contact surface between the steel and concrete to eliminate the influence of friction therebetween. Moreover, to avoid the concrete end-bearing effect below the perfobond rib a 100 \(\times\) 70 \(\times\) 16 mm slot was retained at the bottom of the perfobond rib, to leave space for the styrofoam.