# Evaluation of Horizontal Shear Performance of Composite Girders Using Separable Shear Connectors
## 3 Evaluation of Horizontal Shear Performance
### Fabrication of Horizontal Shear Specimens and Horizontal Shear Tests  
The horizontal shear specimens were constructed according to the specifications in Figure 4. Precast members were fabricated, and composite action was achieved by pouring non-shrink mortar through shear pockets in the upper precast deck members. The dimensions (length \(\times\) width \(\times\) thickness) of the specimens were 1000 mm \(\times\) 600 mm \(\times\) 220 mm, with a bedding layer thickness of 20 mm. Figure 5 and Table 2 reveal that the shear connectors tested in the horizontal shear experiments are categorized into rebar (rebar type; Figure 5a) and embedded separable (DY type) shear connectors. The M-DY (Figure 5b) specimens grouped and fixed several shear connectors by applying a steel plate to the top-surface embedment of the girder concrete, whereas the S-DY (Figure 5c) specimens incorporated shear connectors individually. Each type comprised three specimens, all sharing identical dimensions, rebar arrangements, and material properties for the girders and concrete decks.  
The diameters of the rebar shear connectors and stud bolts in the specimens were consistently 22 mm. The connectors were arranged in a 2 \(\times\) 1 pattern, totaling two connectors/specimen. The design strengths of the precast decks and non-shrink mortar were 40 and 60 MPa, respectively. However, the compression strength test results using cylinder specimens were 51.2 MPa and 53.8 MPa, respectively, showing some difference from the design compressive strength.  
The loading procedure adhered to the testing methods suggested in Eurocode 4, Anne B [3] and was executed using an actuator for horizontal shear tests on the plane. For specimens s1 and s2, repeated loading at a rate of 50 kN/min in cycles ranging from 5-40% (12.5-100 kN) times the expected ultimate load (250 kN) was applied until failure under monotonically increasing displacement control. For the remaining specimens, monotonically increasing displacement controls were employed until failure without repeated loading at 1.0 mm/min. Figure 6 presents an overview of the horizontal shear test specimen setup (1000 kN actuator). The sensor arrangement is detailed in Figure 6. To measure the slip displacement, two sensors were positioned on each side of the concrete deck at the locations of the shear connectors, and strain gauges were installed on both the shear connectors and the concrete, as illustrated in Figure 7.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Specimen**} & \multicolumn{5}{c}{**Shear Connector**} \\ \cline{2-6}  & **Stud type** & **Diameter (mm)** & **Height (mm)** & **Yield strength (MPa)** & **Tensile strength (MPa)** \\ \hline Rebar: s1–s3 & Rebar & 22 & 150 & 452.6 & 578.5 \\ M-DY: s1–s3 & DY & 22 & 150 & 409.9 & 705.1 \\ \({}^{*}\)S-DY: s1–s3 & DY & 22 & 150 & 409.9 & 705.1 \\ \hline \hline \end{tabular}  
* * S-DY=s3: specimen for reconstruction simulation.  
\end{table}
Table 2: Test specimens and their dimensions and parameters.  
Figure 4: Engineering drawing of the shear specimen: (**a**) Assembly drawing (top: top view, top-right: right side view, bottom-left: left side view, and bottom: front view); (**b**) Reinforcement diagram (top: top view, top-right: right side view, and bottom: front view).  
Figure 5: Types of shear connector. (**a**) Rebar; (**b**) M-DY; (**c**) S-DY.  
Figure 6: Test apparatus.  
Figure 7: Sensor locations (top: steel; bottom: concrete). C indicates the strain gauge attached to the concrete surface, and S represents a strain gauge attached to steel.