## 1 Introduction  
The rapid development of transportation infrastructure plays a vital role in higher economic growth. As an essential part of road engineering, bridges are of great significance in improving traffic fluidity and travel convenience [1; 2]. Numerous large-span bridges have been designed and constructed in riverside and coastal areas. The orthotropic steel bridge decks have been widely used due to the advantages of light-weight, high-strength, and easy construction [3]. As the control node of highway transportation, the traffic volume and heavy vehicle proportion of the bridge are much higher than those of ordinary roads. The overload phenomenon frequently occurs, leading to higher requirements for steel bridge deck pavement (SBDP) performance on materials [4]. Studies and practices revealed that epoxy asphalt concrete (EAC), guss asphalt concrete (GAC), and modified stone mastic asphalt concrete (SMAC) were more widely used materials for SBDP [5; 6]. Initially, these materials were introduced into China as single-layer structures. Due to the lack of consideration of environmental variability and the effects of vehicle loads, the pavement suffered severe damage within a short service period [7]. To this end, considering that single-layer pavement structures had difficulty meeting the utilization requirements of bridges, the double-layer pavement structure gradually attracted the attention of researchers. In contrast, double-layered pavement structures can be designed separately and fully integrate the advantages of different materials [8; 9]. After years of research and attempts, EAC + EAC, SMAC + SMAC, and SMAC + GAC are the most commonly used double-layer SBDP structures [10; 11; 12]. Undoubtedly, epoxy asphalt (EA) is a thermosetting material, and the EAC prepared using EA has excellent comprehensive performance, which enables the successful application of the double-layer EAC structure in SBDP [13; 14]. However, the structure has stringent requirements for construction conditions, and the high price limits its further promotion [15]. The double-layer SMAC structure has good skid resistance and water stability and benefits from a short construction period and low cost. However, the structure has insufficient high-temperature stability and was prone to putting disease in hot summers [16]. SMAC + GAC is a double-layer heterogeneous pavement structure that fully utilizes the superiority of both SMAC and GAC. The GAC in the lower layer has good toughness and waterproof properties and synergizes well with the steel bridge plate, while the SMAC in the upper layer is used as a wearing layer due to its satisfactory anti-skid properties. Unfortunately, the SMAC + GAC structure is prone to rutting, potholes, and other defects under continuous high-temperature conditions [17; 18]. Recently, an ERS pavement system consisting of an epoxy bonding chip layer (ECBL), resin asphalt concrete (RAC), and SMAC has been proposed to maximize the characteristics of various materials and to ensure that the deck has good service performance and traffic safety. However, the structure has proven to suffer from frequent rutting defects under the coupled effects of high temperature and heavy loads. However, the damage, such as displacement and upheaval caused by insufficient shear strength between SMAC and RAC, cannot be ignored [19; 20]. It is known that all of the above double-layer SBDP structures have deficiencies. In this case, it is necessary to investigate and attempt a novel SBDP structure. The structure of SMAC + EAC has been revealed to be of great research value [13]. [PERSON] et al. tested and evaluated the performance of four double-layer pavement structures, such as EA-GA, SMA-GA, SMA-EA, and EA-EA. The results indicated that although the SMA-EA structure did not have the best performance in all categories, the structure had good overall performance, and fatigue damage occurred in the top layer of SMAC, which was easy to repair and maintain [8]. [PERSON] et al.