Structures 29 (2021) 966–978 Available online 16 December 2020 2352-0124/© 2020 Institution of Structural Engineers. Published by Elsevier Ltd. All rights reserved. Experimental investigation on damage and wave propagation of PVB laminated glazing structures under impact loading Amr A. Nassr a, * , Tomomi Yagi b , Takashi Maruyama c , Gen Hayashi d a Sustainable Design Engineering, University of Prince Edward Island-Cairo Campus (hosted by Universities of Canada in Egypt), Dept. of Civil Engineering, Assiut University, 71516, Egypt b Dept. of Civil & Earth Resources Eng., Kyoto University, Kyoto 615-8540, Japan c D.P.R.I., Kyoto University, Kyoto 611-0011, Japan d Dept. of Civil Eng., Osaka City University, Osaka 3-3-138, Japan A R T I C L E INFO Keywords: Flexure Impact Glass Strain rate Wave ABSTRACT Experimental investigation on the damage and wave propagation characteristics in PVB laminated glass panels subjected to impact loading was conducted. By applying different impact energies, the effect of two projectile confgurations, a wooden post and steel ball, was studied. The effect of impact location was also investigated. The dynamic response of the panels was measured at different locations on the test panels using strain gauges. Damage and transient response and wave propagation characteristics of test panels were reported and compared. The results showed that fexural wave was the predominant wave in the response. In addition, in-plane compressive wave was also observed. It was also shown that while the projectile contact area affected the maximum transient response and crack propagation characteristics, it had a limited effect on the perforation threshold. For panels impacted at the corners, coupled strain waves were created by wave refection processes when the waves reached the panel boundaries. Moreover, the impact velocity had a pronounced effect on peak strain and strain rates of test panels. 1. Introduction The primary cause of glass failure during severe windstorms is the windborne debris impacts [1,2]. Laminated glass (LG), which consists of two or more layers of glass plies adhered by an interlayer made of polyvinyl butyral (PVB), provides inherent resistance to building enve- lope breaches caused by the combined effects of wind pressure and windborne debris impacts during severe windstorms. The major pur- poses of the PVB interlayer are to provide impact energy absorption and adhesion to the glass plies. Unlike monolithic panes, LG will not shatter into fragments when glass plies break as most of fragments will adhere to the PVB layer. Therefore, the risk of people injuries can be consid- erably reduced. Despite their many advantages, the impact strength evaluation of LG involves several complexities limiting their effcient application because of the composite nature of the structure. Due to the cost of full-scale experimental evaluation, there are quite few experimental investigations available in the literature on the impact resistance of LG. Grant et al. [3] investigated the damage threshold of LG structures using granite impactor up to impact velocity of 20 ms 1 . The thickness of the outer glass layer was found to be the primary parameter affecting the critical velocity, defned as the lowest velocity at which damage took place during a set of 30 impact tests. Zhang et al. [4] experimentally investigated the response of laminated glass of different interlayer thicknesses under the impact of wooden block of 4.0 kg at impact velocity of 15 ms 1 . This study showed that increasing in the interlayer thickness effectively increased the glass capacity to prevent debris penetration. Chen et al. [5] performed impact tests to investigate the radial and circular crack propagation in a LG panels under drop weight impact. The velocity of radial and circular crack was measured using a high-speed camera. The increase in impact velocity resulted in an increase in radial and circular crack velocity, while the PVB inter- layer thickness was found to have an opposite effect on the radial and circular crack velocity. Most of above-mentioned experimental studies only provided limited data on the transient response of LG panels under impact loading with emphasis on low-velocity impacts produced by drop weight experiments. Therefore, more experiments conducted on well- * Corresponding author. E-mail addresses: amrnassr@aun.edu.eg (A.A. Nassr), yagi.tomomi.7a@kyoto-u.ac.jp (T. Yagi), maruyama.takashi.8w@kyoto-u.ac.jp (T. Maruyama), hayashi-g@ osaka-cu.ac.jp (G. Hayashi). Contents lists available at ScienceDirect Structures journal homepage: www.elsevier.com/locate/structures https://doi.org/10.1016/j.istruc.2020.12.003 Received 1 August 2020; Received in revised form 3 November 2020; Accepted 1 December 2020