# Evaluation of Horizontal Shear Performance of Composite Girders Using Separable Shear Connectors
## 1 Introduction
Based on beam tests with high-strength concrete and other specimens, [PERSON] and [PERSON] [2] stated that the existing design codes underestimated the shear strength of high-strength concrete. [PERSON] [3] conducted horizontal shear tests on the joints of precast members by varying the type of filler, haunch height, and shear connector shape, and proposed design equations tailored for rough joint surfaces. [PERSON] et al. [4] designed and tested composite beams to devise a rational method for evaluating and designing the horizontal shear strength of composite concrete members. Their tests considered the type of member, the area ratio of members to cast-in-place concrete, and the spacing of the shear rebar. They reevaluated the experimental results obtained from prior research, assessed the accuracy of existing design standards based on the horizontal shear-strength test results for various member types, and introduced improved horizontal shear-strength equations. [PERSON] and [PERSON] [5] applied stress-field theory in experiments designed to induce horizontal shear failure in composite beams to delineate the ultimate limit state of beams newly cast over existing reinforced concrete girders. They proposed a novel method to calculate  
Figure 1: Case study on the removal and reconstruction of aged concrete slabs. (**a**) Cutting aged concrete slab; (**b**) Cutting rebar shear connectors; (**c**) Reinstallation of rebar shear connectors; (**d**) Complete reconstruction of new PC slab. the shear strength considering the tensile enhancement effect of concrete and variations in the maximum compressive strength under axial stress conditions. [PERSON] et al. (2018) assessed the bond strength at the precast-deck-girder interface by conducting direct shear tests. They evaluated the bond strength at the interface of the composite section by considering the surface conditions, shear connector shapes, and reinforcement volume. Their analysis focused on the bond strength variations influenced by surface conditions and bedding layer thickness. Notably, they compared studs (which are inseparable) with conventional rebar shear stirrups. Several researchers ([PERSON] et al., 2017; [PERSON] et al., 2018; [PERSON] et al., 2018) have investigated separable shear connectors using bolted connections for composite structures comprising steel girders and concrete decks. However, limited studies have been conducted on separable shear connectors for girders and precast concrete decks. In this study, a novel embedded demountable shear connector that can easily separate and replace aged concrete slabs was developed and experimentally verified. The remainder of the paper is organized as follows. Section 2 summarizes the horizontal shear-strength design standards of representative countries and analyzes the study cases of existing researchers on horizontal shear tests and horizontal shear-strength evaluation related to precast concrete slab composite girders. Section 3 details horizontal shear tests performed on the developed embedded demountable shear connector, and the test results were compared with those from the existing rebar shear connector method. The findings confirmed that the horizontal shear strength of the developed shear connector satisfied the relevant design standards. Finally, Section 4 details the manufacturing of prestressed concrete (PRC) composite girders using the developed shear connector and bending tests. The experiments confirmed that, compared with the existing rebar shear connector method, the developed shear connector exhibited equivalent or improved performance in both flexural and horizontal shear strengths.