## 1 Introduction  
Steel-concrete-steel (SCS) sandwich composite structures consist of two steel plates and a central concrete core. Mechanical connectors (such as headed studs, binding bar, and J-hook) or adhesive materials (such as epoxy) are utilized in the steel-concrete interface to form an integral unit to resist external loads. Versatile applications of SCS composite structures in building cores, anti-blast and impact protective structures, road and bridge decks, shield and immersed tunnels, nuclear wall, offshore and Arctic offshore structures, liquid containment, and oil storage [1; 2; 3; 4; 5; 6] are carried out due to the mechanical characteristics (such as high capacity, rigidity, blast and impact resistance, and good performance in construction efficiency and leakage prevention) of SCS composite walls. In SCS walls, different types of materials, such as fiber-reinforced polymer (FRP) concrete, foamed concrete, lightweight concrete (LWC), ultra-lightweight cementitious composite material (ULCC), and high strength steel (HSS), are used to improve the structural performance such as compressive and shearing capacities, which are lighter weight compared with conventional walls [7; 8; 9; 10]. To the best of the authors' knowledge, none of these studies have implemented damping materials into practice to optimize the performance and extend the application of such potential composite structures. One of these materials is rubber, which is commonly used for energy dissipation, impact resistance, and protective design of structures against blast. In order to improve the damping characteristics of composite structures, bonding an elastomeric patch or a layer (e.g., a layer with a rubber material) in particular positions of structures is one of the most common solutions. As shown in Figure 1, several studies on auto-motive and aerospace fields have been carried out on the study of damping properties of multi-coated thin-walled composite mechanical components such as plates, shells, and beams [11; 12; 13]. It can be observed that introducing layers of materials with pronounced damping properties such as high damping rubber materials [14] and viscoelastic plies constrained on their outer surfaces by stiffer layers called constrained-layer damping (CLD) treatment [15], can improve the damping properties of composite materials. Besides, there exist several studies, which investigated the effects of damping characteristics on sandwich box columns, where the damping core can be used as a viscoelastic layer (VEL), or an electro-rheological (ER) or magneto-rheological (MR) fluid core [16; 17]. Recently, vibration control has become an effective method to reduce the response of civil engineering structures under horizontal load [18; 19; 20] and viscoelastic layers have been adopted particularly in the form of sandwich box columns as an alternative technological solution for efficient earthquake control (passive vibrations control) [21]. More recently, the seismic performance of reinforced concrete (RC) columns strengthened with bonded rubber plates was experimentally studied. It was observed that the equivalent damping ratio under peak load, the ductility, and the energy dissipation coefficient of RC columns attached to rubber plates were improved [22]. Rubber layers are also typical sources to increase the impact resistance of structures. For example, [PERSON] et al. [23] and [PERSON] et al. [24] improved the impact resistance of hybrid structures through the modification with epoxy resin with rubber. Then, the damping properties of hybrid structures with rubber layers under high- and low-velocity impact loads were investigated. It was found that the rubber layer could absorb the impact energy, decrease the internal damage, and increase the damage threshold in real-life applications such as laminar airfoils [25; 26; 27].