# Bending Performance of Concrete Sandwich Walls with Actual Boundary Conditions
## 1 Introduction  
Exterior wall panels are important parts of a structure, playing an indispensable role in sheltering against environmental conditions such as wind and rain. In the meantime, it is necessary for the wall panel to have satisfactory thermal and sound insulation, which is beneficial in providing a comfortable living environment for human beings. Moreover, a low self-weight is also expected for sandwich walls, especially in steel structures. Therefore, various lightweight and thermal insulation materials have been employed for use in the sandwich layer within the wall panel. Moreover, many other structural components also adopted sandwiched configurations [1; 2; 3]. However, these materials have a low bearing capacity. This also leads to more challenges for sandwich walls under bending conditions. Many scholars have carried out experimental and numerical programs in order to analyze the performance of concrete sandwich walls under various loading conditions [4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14]. Among them, [PERSON] et al. [5], [PERSON] and [PERSON] [8] and [PERSON] et al. [9] performed experimental investigations on concrete sandwich wall panels in order to analyze their seismic performance. [PERSON] and [PERSON] [6] and [PERSON] et al. [11] analyzed the thermal behavior of the concretesandwich walls based on experimental and numerical approaches. [PERSON] et al., [4] reported the test results of FRP-reinforced concrete sandwich walls under concentric axial loading. [PERSON] et al., [10] discussed the vulnerability of concrete sandwich walls to fire, and [PERSON] et al. [13] studied the corrosion performance of the concrete sandwich wall panels. In addition, [PERSON] et al. [7] developed an analytical model to predict the mechanical behavior of concrete sandwich walls under various loadings. It can be concluded that sandwich wall panels have attracted the attention of many scholars, and are widely employed in engineering practice. Until now, great attention has been paid to the bending performance of various sandwich walls [15; 16; 17; 18; 19; 20; 21; 22]. For example, [PERSON] et al. [19] presented an experimental and numerical investigation of sandwich panels with a vegetal-fabric-reinforced cementitious matrix layer. [PERSON] et al. [20] proposed the design of a sandwich panel under bending conditions. [PERSON] [21] examined the behavior of recycled glass bead sandwich panels under bending conditions. [PERSON] et al. [22] reported the bending performance of curved sandwich panels. From these studies, it was revealed that the sandwich wall panels exhibited satisfactory bending performance. Among these studies, the sandwich panels were subjected to bending loads with pinned supports. The sandwich panels were generally employed as exterior walls and were connected to the main structure, usually based on angled steel connectors, in which the actual constraint of the sandwich wall panel used as an exterior wall was significantly different from the pinned supports. Therefore, it is necessary to detect the bending performance of sandwich walls under actual boundary conditions. Against the background, current investigations mainly explored the bending performance of the concrete sandwiched wall under pinned supports. Little attention has been paid on the bending behavior of concrete sandwiched wall under actual support constraints. This paper attempts to discuss the out-of-plane bending performance of sandwich walls connected to the top and bottom beams, in which the sandwich wall analyzed in this paper did not bear vertical loads. In total, four sandwich wall specimens with extruded polystyrene foam (XPS) layers were prefabricated. Different loading directions and opening details were designed for the various specimens. Out-of-plane bending tests were performed to detect the bending behavior, and typical failure modes were discussed. Load-deflection curves were also characterized in some key points.