# Numerical Investigation on Novel Shear Connectors in Prefabricated Composite Beams
## 1 Introduction  
The concept of the assembly style of bridge structures has not been widely considered until recently, although the prefabricated composite bridge has a long and successful history. The use of prefabricated systems in bridge construction has recently been the subject of much attention and interest among bridge jurisdictions as a way of improving bridge construction [1]. In particular, prefabrication offers several benefits, such as reduced waste generation, improved site safety, enhanced quality under factory production, promotion of recycling construction waste, greater environmental protection, process standardization, shorter lead time, and sustainability, as studied by [PERSON] [2] and [PERSON] [3]. The Federal Highways Administration (FHWA) publication titled \"Connection Details for Prefabricated Bridge Elements and Systems\" outlines the state of practice in the United States for accelerated bridge construction (ABC) [4]. However, there are still various engineering problems that have not been solved yet, especially for the design and construction of shear connectors in prefabricated composite beams. The connection of precast concrete bridge decks and steel beams is a very important part of the construction [5], in which shear studs are used. There are several methods for theshear studs to connect the existing decks. Some reserve shear stud holes in the steel flange plates and precast concrete decks, thus achieving composite action through post-installed shear studs to connect the existing deck to the steel beams. The methods of installing the shear studs and the behavior of the post-installed shear connectors were studied in recent years by [PERSON] [6], [PERSON] [7], and [PERSON] [8]. This method slightly weakens the concrete decks but the hole requires high construction accuracy. Composite action between the steel beams and deck elements can also be achieved by using headed studs cast into the beam. Precast decks are always made with full thickness pockets or with blind pockets with grouting ports, which were reported in the research of [PERSON] [3] and [PERSON] [9]. This method cannot avoid weakening the concrete and causing creep and shrinkage in the cast concrete. Another method is shown in Figure 1, the shear studs are precast in the concrete deck, then, the precast decks are welded to the steel beam to achieve composite action. This approach has been applied to the assembly of a simple supported beam bridge across the Fuling River, which is upstream of the Yangtze River tributaries. The studs of this kind are called \"prefabricated shear studs\" in this paper, according to the studs' arrangement. The shear studs being arranged horizontal to the steel upper flange is the unique characteristic of prefabricated shear studs, which may affect the shear behavior of the structure. The constraint conditions of the concrete are changed because of the stud arrangement, which can improve the shear behavior of the shear studs during the longitudinal loading stage, and some design notes were proposed in the efforts of many researchers such as [PERSON] [10], [PERSON] [11], and [PERSON] [12]. In terms of construction, the horizontal arrangement of the shear studs is to facilitate the prefabrication and assembly of concrete decks. In terms of mechanics, the horizontal arrangement of shear studs mainly plays a role in resisting shear and uplift in the composite bridge deck. Unfortunately, the current research results are not enough to guide the design of prefabricated shear studs, because of the limited results and the different design concept. Recently, the push-out test and finite element simulation are the most popular research methods of shear connectors, as well as other new composite structures, including  
Figure 1: Arrangement and construction of prefabricated composite beam shear studs. steel-UHPC composite structures, etc. [13; 14]. Many researchers have made remarkable achievements on conventional shear studs, such as [PERSON] [15] and [PERSON] [16].