# Evaluation of Horizontal Shear Performance of Composite Girders Using Separable Shear Connectors
## 3 Evaluation of Horizontal Shear Performance  
### Structural Characteristics of Embedded Separable Shear Connectors  
The proposed embedded separable shear connector comprised a nut anchor embedded within the girder, a hollow U-shaped component, and a stud bolt designed to handle actual shear forces (Figure 3). Initially, the nut anchor was pre-embedded in the girder, the hollow U-shaped component was threaded, and the stud bolt was fastened. This action coupled the U-shaped component and embedded nut through bolt tension. Subsequently, after placing the deck, a non-shrink mortar was poured to fully integrate the deck with the U-shaped component. \begin{table}
\begin{tabular}{c c c c c} \hline \multirow{2}{*}{**Design Codes**} & \multirow{2}{*}{**Horizontal Shear-Strength**} & \multirow{2}{*}{**Variable**} & \multicolumn{2}{c}{**Interfacial Roughness**} & \multirow{2}{*}{**Limit Value**} \\ \cline{3-4}  & & & **Smooth** & & **Rough** \\ \hline \multirow{4}{*}{ACI-318 [10]} & \(v_{nh}=c+\mu\rho_{v}f_{y}\) & \(c(\text{MP}_{\text{a}})\) & 0.56 & 1.8 & \(v_{nh}\leq 3.5\text{MP}_{\text{a}}\), \\  & \(\mu\) & - & 0.6 & \(A_{v}\geq A_{v,nink}\) \\  & \(v_{n}=\mu\rho_{v}f_{y}\) & \(\mu\) & 0.6 & 1.0 & \(v_{nh}>3.5\text{MP}_{\text{a}}\), \\  & \(v_{n}=\mu\rho_{v}f_{y}\) & \(K_{1}\) & 0.2 & 0.2 & \(V_{n}\leq K_{1}f_{c}^{\prime}\) \\  & \(K_{2}(\text{MP}_{\text{a}})\) & 5.5 & \(3.3+0.08f_{c}^{\prime}\) & \(V_{n}\leq K_{2}\) \\ \hline \multirow{4}{*}{AASHTO LRFD [11]} & \(c(\text{MP}_{\text{a}})\) & 0.52 & 1.65 & \multirow{4}{*}{\(v_{n}\leq K_{1}f_{c}^{\prime}\), \(V_{n}\leq K_{1}f_{c}^{\prime}\), \(K_{1}\)} \\  & \(v_{n}=c+\mu\big{(}\rho_{v}f_{y}+\sigma_{n}\big{)}\) & \(\mu\) & 0.6 & 1.0 & \(V_{n}\leq K_{1}f_{c}^{\prime}\), \(K_{1}\) \\  & \(K_{1}\) & 0.2 & 0.25 & \(V_{n}\leq K_{2}\) \\  & \(K_{2}(\text{MP}_{\text{a}})\) & 5.52 & 10.34 & \\ \hline EC2 [12] & \(c_{Rdi}=c(\text{MP}_{\text{a}})\) & 0.35 & 0.45 & \(v_{Rdi}\leq 0.5\rho f_{c\prime}\), \(v=0.6(1-f_{d}/250)\) \\  & \(c_{fcd}+\mu\rho_{n}+\rho_{v}f_{yd}(\mu\sin\alpha+\cos\alpha)\) & \(\mu\) & 0.6 & 0.7 & \(c_{n}\leq 0.6f_{cd}\) \\ \hline \multirow{4}{*}{KDS [13]} & \(\mu_{1}\) & 0.35 & 0.45 & \multirow{4}{*}{\(v_{d}\leq 0.5\Phi_{c}vf_{d}\)} \\  & \(v_{d}=\Phi_{c}\mu_{1}f_{\text{c}xt}+\mu_{2}f_{n}+\Phi_{2}\mu_{2}gf_{y}\) & \(\mu_{2}\) & 0.6 & 0.7 & \(v_{d}\leq 0.5\Phi_{c}vf_{d}\) \\ \cline{1-1}  & \(\Phi_{c}\) & 0.65 & 0.65 & 0.65 & \(v_{d}\leq 0.5\Phi_{c}vf_{d}\) \\ \hline \multirow{4}{*}{Note: \(v_{nh}(=v_{n}=v_{Rdi})\) represents the horizontal shear strength, \(c\) represents the interface bond coefficient, \(\mu\) is the friction coefficient, \(\rho_{v}\) is the ratio of the shear connector area (\(A_{v\rho}f_{y}\)) to the concrete contact area (\(A_{v\rho}\)) of the shear friction surface, \(f_{y}\) is the yield strength of the shear connectors (rebar) traversing the shear friction surface, and \(f_{c}^{\prime}(=f_{cd})\) is the design compressive strength of the concrete. Here, \(K_{1}\) denotes the concrete strength ratio critical for interface shear resistance, and \(K_{2}\) represents the interface shear resistance limit. The compressive strength must exceed 16.5 MPa. \(f_{cd}\) is the design tensile strength of the concrete, \(\sigma_{n}\) denotes the stress induced by external loads perpendicular to the contact surface (compression: positive, tension: zero), \(f_{yd}\) is the design yield strength of the shear bar (within specified limits 600 MPa), and \(f_{d}\) is the compressive strength of an individual specimen (12–90 MPa). Here, \(\alpha\) is the angle between the shear connectors and the interface, constrained within the range of \(45^{\circ}\leq\alpha\leq 90^{\circ}\).  
\end{table} 
Table 1: Horizontal shear strength by design codes. Figure 3: Conceptual diagram of embedded demountable shear connector. (**a**) Components of DY–shear connector; (**b**) Girder–slab composition; (**c**) Separation of girder and slab.