## 1 Introduction
In this research, practical solutions for the development of the CSC shear connectors are presented in SCS slabs. Figure 1: Shear connectors in SCS sandwich structures. (**a**) C-shaped connectors, (**b**) L-shaped connectors, (**c**) overlapped headed studs in DSC system, (**d**) friction welding connectors in Bi-steel structure, (**e**) J-hook connectors, (**f**) corrugated-strip connectors (CSC). Many types of research have been done on the performance of SCS sandwich members. In 2011, [PERSON] and [PERSON] [24] studied eight SCS slabs which consist of a lightweight concrete core sandwiched in between two steel plates interconnected by J-hook connectors under concentrate static load. The maximum resistance of the SCS slabs was governed by either the flexural resistance of the slab or punching shear resistance of the concrete core. After that, in 2014, [PERSON] and [PERSON] [25] evaluated the behaviour of J-hook SCS sandwich slabs with lightweight concrete core subject to impact load. Impact tests were carried out using an instrumented drop weight machine. Test data such as deflection- and impact force-time history and permanent deformation after impact were reported. Test observation showed that J-hook connectors provide an effective means to interlock the top and bottom steel faceplates, preventing them from separation upon impact. Steel fibres were added into the concrete core of selected test specimens to evaluate their effectiveness in reducing the brittleness of concrete due to dynamic loads. In another investigation in 2017, [PERSON] and [PERSON] [26] assessed the flexural and shear performance of SCS sandwich slabs under concentrate loads. For this aim, six simply supported slabs with different shear spans, section depths and steel configurations were tested under concentrate loads applied at the centre. After the tests, parts of the steel plates were taken off to observe the crack distribution. The observed modes of failure included flexural yielding and shear punching. The former was initiated by tensile yielding of the bottom steel plate, while the latter was primarily due to punching shear failure of the concrete core. Besides, a theoretical model was developed to predict the resistance of SCS slabs under concentrate loads. In 2019, [PERSON] et al. [27] investigated the performance of SCS slabs under contact blast loading by experiment and numerical method. For this purpose, three small-scale specimens under contact detonation were tested to obtain the failure modes, mid-span deflection, and dynamic response. Nonlinear 3D finite element models were also established to assess the blast behaviour using Arbitrary-Lagrange-Eulerian (ALE) coupled with Fluid-structure interaction (FSI) algorithm. The results indicated that the failure modes of these slabs were summarized as three types such as type I, type II and type III from both experimental and numerical results. The damaged areas of concrete in slabs were more substantial than that of RC slab. Recently, [PERSON] et al. [28] evaluated the Low-velocity impact performance of curved SCS sandwich slabs with bolt connectors. Experimental outcomes including impact force history, displacement history and permanent deformation were analysed to reveal the influences of concrete core and steel plate thickness as well as shear connectors' spacing on the impact performances of SCS slabs. Meanwhile, three failure types were observed from the nine specimens subjected to impact load. The presence of bolt connectors was proven to be an effective way to prevent the detachment of steel plates from the concrete core. It turned out that concrete core was the central part to dissipate impact energy, followed by a top steel plate and bottom steel plate. [PERSON] et al. [29] conducted test program to investigate the behaviour of SCS which consist of a normal weight concrete core sandwiched in between two steel plates interconnected by stud bolt shear connectors under concentrate static loading.