Blast response of GFRP-strengthened infill masonry walls Saleh H. Alsayed, H.M. Elsanadedy, Zaki M. Al-Zaheri, Yousef A. Al-Salloum, H. Abbas ⇑ MMB Chair for Research and Studies in Strengthening and Rehabilitation of Structures, Dept. of Civil Engineering, College of Engineering, King Saud University, P.O. Box 800, Riyadh 11421, Saudi Arabia highlights  Studied the performance of strengthened infill unreinforced masonry walls against blast loads.  Back face of the wall was strengthened using two layers of GFRP sheets.  The blast tests were conducted for varied scaled distances using C-4 explosive.  Numerical analysis was performed using ANSYS-AUTODYN.  GFRP composite with proper end anchorage resists low to moderate blast loads and contains flying debris. article info Article history: Received 4 October 2015 Received in revised form 24 March 2016 Accepted 11 April 2016 Keywords: Blast Infill masonry wall GFRP Strengthening Concrete masonry blocks FEA abstract Recent spurt in terrorist activities throughout the globe have drawn the attention of engineers and sci- entists to the vulnerability of buildings and infrastructure to blast loads. The failure of infill masonry walls has been widely witnessed even in low magnitude blasts. The failure of masonry often leads to fly- ing debris resulting in loss of life and disabilities/injury to a large number of people. This study focuses on the performance of strengthening scheme for infill masonry walls using GFRP sheets against blast loads. Strengthened walls were tested against blast loads for the evaluation of the out-of-plane performance of strengthened walls as against the unreinforced masonry (URM) walls. The test results have been com- pared with the blast analysis performed using ANSYS-AUTODYN. Some parametric studies of field inter- est were also carried out for understanding the behavior of strengthened walls against blast loads and deriving some useful conclusions. The numerical simulation technique can provide a theoretical refer- ence for the design of walls and may help in reducing the requirement of extensive testing. The most sig- nificant parameter for assessing the severity of damage in structures under blast loads is the scaled distance. It has been demonstrated that the use of GFRP composites with proper end anchorage offers great potential for the retrofitting of URM infill walls to resist low or moderate blast loads and contain flying debris. Ó 2016 Elsevier Ltd. All rights reserved. 1. Introduction Recent rise in terrorist activities around the globe have attracted attention of engineers and scientists towards the vulner- ability of buildings and infrastructure to blast loads. The conse- quent effects of these loads may range from minor damage to structural collapse accompanied by huge loss of life. The masonry, which is the oldest and the most widely used building material [1–3] either in masonry buildings or in the form of infill walls in reinforced concrete (RC) framed buildings, suffers most damage. Even if there is no complete damage or structural collapse, the flying debris may cause significant loss of lives or injuries. As a result, efforts were made by several investigators to examine feasi- ble methods for strengthening masonry walls in order to enhance their resistance to blast loads. Although several techniques have been tried but one of the most popular methods of retrofitting unreinforced masonry (URM) walls is the application of fiber- reinforced polymers (FRP) to its surface. As the blast causes a pres- sure to be exerted on the surface of a wall, the flexural resistance of the wall needs to be enhanced. The applications of externally affixed FRP materials have been shown to improve the out-of-plane bending resistance of walls. Many investigators have used externally applied FRP strips for the retrofitting of URM walls against lateral static loads and found these to be effective in increasing the load carrying capacity. Velazquez-Dimas et al. [4] used glass fiber-reinforced polymer (GFRP) strips for the strengthening of single and double wythe http://dx.doi.org/10.1016/j.conbuildmat.2016.04.053 0950-0618/Ó 2016 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: abbas_husain@hotmail.com (H. Abbas). Construction and Building Materials 115 (2016) 438–451 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat