# Research on Out-of-Plane Bending Test of PVB Laminated Glass Plate with Different Number of Layers
## 1 Introduction
Conducting bending experiments on laminated glass plates is considered the most vital method for analyzing their mechanical response [25], providing a means for theoretical verification and numerical analysis. Researchers have focused on double-layered glass plates to experiment with the load-bearing capacity of laminated glass under bending conditions. [PERSON] et al. [26] performed bending load tests on cold-bent laminated glass with varying cold bending rates and interlayer thicknesses. Cold-bent glass is produced by applying external forces to flat glass to induce deformation, permanently setting it to the desired curved shape, with the cold bending rate defined as the curvature of the curved arc. They observed that the ultimate load-bearing capacity of laminated glass decreases with an increase in both the cold bending rate and the interlayer thickness. [PERSON] et al. [22] conducted a three-point bending test to study the impact of a non-uniform thermal gradient on the bending performance of laminated glass. They demonstrated that the bending deformation of laminated glass under heating is significantly more pronounced than that without heating, with residual deformation being observable after unloading. In addition, [PERSON] et al. [27] measured the flexural strength of laminated glass with various interlayer materials and thicknesses. The experimental results indicated that PVB laminated glass exhibits a greater extent of average deformation and can bear a higher average load compared to vinyl acetate laminated glass. The average pre-fracture deformation was found to increase with the rise in interlayer thickness. [PERSON] et al. [28] investigated the influence of polymer interlayer thickness, glass, and polymer type on structural performance through static and low-speed loading experiments on laminated glass. Their analysis focused on the effects of interlayer type, thickness, and loading method on the fracture patterns of each glass layer. [PERSON] et al. [29] conducted bending experiments on two types of laminated materials under four-sided simple support, discovering that the bending stiffness of LG with polymer interlayers increases with a rise in the thickness of the lamination. However, the LG with a polyvinyl butyral interlayer exhibited insensitivity to changes in interlayer thickness, provided there was no significant deflection bending. [PERSON] et al. [9] performed a four-point bending test on LG plates to compare the effects of temperature, load duration, and adhesive thickness on the overall deflection and stress distribution within the plate. They presented an approximate calculation method for determining the bending stiffness of the plate. Although scholars have conducted experimental studies on various factors affecting the bending behavior of laminated glass, these studies have predominantly focused on two-layer glass plates, with no experimental studies on three-layer glass plates. The relationship between the number of glass layers and the ultimate load-carrying capacity of PVB laminated glass, as well as the relationship between the number of layers and the bending stiffness of PVB laminated glass, remain to be further researched. To study the influence of the number of glass layers on the bending behavior of PVB LG (Trading Company, Guangzhou, China), and to address the gap in experimental research on three-layer PVB LG, this study conducted and analyzed bending experiments on one-layer, two-layer, and three-layer PVB LG under out-of-plane loading. During the loading process, the out-of-plane displacement and surface strain of the glass plate were monitored and analyzed. Load-deflection curves were plotted based on these observations, and the distribution of deflection and strain in the plane was obtained. The influence of layer count on stiffness and ultimate load was examined. Surprisingly, it was found that the stiffness of PVB LG does not increase linearly with the number of layers.