## 1 Introduction  
In recent years, many bridges have been constructed for the convenience of travel and the alleviation of traffic jams, but the construction of bridges with conventional methods is time-consuming and costly [1]. There is, therefore, an urgent need for accelerated bridge construction techniques to reduce the cost and shorten the construction time. Precast bridge panels are often adopted to accelerate the construction of a bridge, and joints are required to connect the adjacent precast bridge panels. Therefore, the joints play a crucial role in ensuring the integrity of the connected bridge panels, and they should have adequate strength. However, in the process of operation, the bridge deck system faces the problem of poor durability of the bridge panels, pavement, and steel deck [2]. Especially, the joints of the bridge deck are prone to shear and durability damage due to the influence of vehicles; thus, more attention should be paid to them. In order to improve the ultimate shear capacity and durability of wet joints, three approaches are mainly adopted: (1) grout the wet joints with suitable high performance materials, (2) change the overlapping form of reinforcement at the wet joint, and (3) set shear keys at wet joints. As a grouting material, ultra-high-performance concrete (UHPC) has discontinuous void structure, which can reduce the entry of water molecules. It has stronger durability than traditional concrete and is suitable for the wet joints of a steel-concrete composite bridge [3]. Due to its outstanding mechanical performance, ultra-high-performance fiber reinforced concrete (UHPFRC) is also used in wet joints to improve the integrity of adjacent bridge panels [4; 5; 6]. Changing the overlapping form of steel bars by using a headed bar can not only avoid welding but also improve the shear capacity and durability of the wet joint [7; 8; 9]. For example, the mechanical performance of wet jointscan be improved by using U-loop bars [10; 11]. In general, the joints for connecting precast bridge panels are categorized as wet joints and dry joints [12]. Dry joints such as shear keys are widely used in concrete segmental bridges and precast concrete box girder bridges, and they can improve the shear capacity [13; 14; 15; 16; 17; 18; 19; 20]. Wet joints with shear pockets are also adopted to connect the concrete panels and girders to increase the shear capacity of the full-depth precast concrete bridge panels [21]. Since the wet joints of orthotropic bridge deck are prone to concrete cracking, [PERSON] et al. [22] designed five types of new wet joints to improve the crack resistance of a precast composite deck system. [PERSON] et al. [23] and [PERSON] et al. [10] also employed dovetail-shaped wet joints to improve the shear capacity and crack resistance of a steel-concrete composite bridge. Based on the comparative model test, [PERSON] et al. [24] proved that the crack resistance of a T-shaped joint is better than that of an I-shaped joint in a steel-concrete composite bridge. The seismic performance of steel-concrete composite bridges should be considered in bridge operation, especially for multi-span precast steel-concrete composite bridges, which are very sensitive to earthquake loading [25]. Thus, it is very important to improve the seismic performance of bridges. This can be achieved by using a friction pendulum device (FPD) as an isolation system placed between the deck and the top of the pier, which is proven as an effective and economical seismic retrofit strategy [26; 27; 28]. Although UHPC can improve the mechanical properties of concrete at wet joints, the curing conditions of UHPC are too harsh. Changing the overlapping form of reinforcement at the wet joint will increase not only the steel consumption but also the construction time. Moreover, existing shear keys in wet joints are simple in configuration and cannot avoid stress concentration.