Journal of Building Engineering 27 (2020) 100975 Available online 3 October 2019 2352-7102/© 2019 Elsevier Ltd. All rights reserved. Quasi-static cyclic tests of confined masonry walls retrofitted with mortar overlays reinforced with either welded-wire mesh or steel fibers Julian Carrillo a, * , Jose A. Pincheira b , Leonardo E. Flores c, d a Dept. of Civil Engineering, Nueva Granada Military University UMNG, Colombia b Dept. of Civil and Environmental Engineering, University of Wisconsin-Madison, USA c National Center for Disaster Prevention, CENAPRED, Mexico d Dept. of Civil Engineering, National Autonomous University of Mexico, UNAM, Mexico A R T I C L E INFO Keywords: Confined masonry walls Retrofit Mortar overlay Welded-wire mesh Steel fibers ABSTRACT Overlays made of high-slump mortar reinforced with a steel welded-wire mesh are one of the most common techniques to retrofit low-rise confined masonry walls. An alternative to this technique is the use of Steel Fiber- Reinforced Mortar (SFRM) overlays to strengthen and enhance the shear capacity of existing masonry walls. In this paper, test results are presented of two full-scale, multi-hollow clay brick confined walls strengthened with reinforced mortar overlays. The overlays consisted of a high-slump mortar reinforced with a) welded-wire reinforcement in one wall and b) hooked end steel fibers in the second wall. Overall height and length of the walls were 2.5 m and 4.24 m, respectively. Both walls were tested under in-plane, quasi-static, reversed cyclic lateral loads. Performance of the retrofitted walls is evaluated in terms of crack patterns, hysteretic response, and lateral strength and displacement capacity. The test data show that both retrofit techniques performed very well and they each restored the strength and deformation capacity to that of the original walls. 1. Introduction Low-rise Confined Masonry Wall (CMW) buildings are a very popular type of residential construction in Latin America. Many have been built, however, with substandard or obsolete reinforcement details, and are often found inadequate to sustain the displacement demands expected during a major seismic event. Observations from past earthquakes have shown that these substandard CMW systems are often prone to failure by out-of-plane instability, by in-plane diagonal tension, or by sliding shear [1]. Bond failure between the masonry wall and the confining concrete elements has also been observed. Although low-rise residential CMW construction designed and built with the provisions developed following the 1985 Mexico City earthquake showed very good performance during the recent 2017 Puebla-Mexico earthquake, retrofit of CMW built in accordance with older provisions is deemed necessary in Mexico [2]. Among the techniques available for the seismic retrofit of masonry walls, e.g., grout injection, reinforced mortar and concrete overlays, or Fiber Reinforced Polymer (FRP) sheets; overlays made with high-slump mortar or micro-concrete reinforced with welded-wire steel reinforce- ment are most commonly used [1,3,4]. These overlays may be provided on one or both wall faces. Test results have demonstrated that with this technique, the original strength of the walls cannot only be restored, but also be increased significantly [3]. For instance, strengthening of unre- inforced masonry using welded wire mesh and micro-concrete, also known as Ferro-cement, results in significant enhancement in shear strength and ductility of unreinforced brick masonry [4]. Test data also show that the deformation capacity and amount of cracking of the strengthened walls depend on the steel reinforcement ratio, the use of overlays on one or both faces, and on the damage level previously sus- tained by the wall [3]. The fabrication and installation of overlays with welded wire reinforcement is labor intensive, time consuming, and can be costly. Use of alternative methods and materials can help reduce labor and costs while improving seismic performance. Some studies have focused on the use of fiber reinforced mortar for seismic strengthening of ma- sonry infilled RC frames [5,6] or unreinforced masonry (URM) buildings using solid bricks [7,8]. Flexural-failure dominant URM walls strengthened with polyvinyl alcohol fiber reinforced mortar overlay exhibit significant increase in the wall drift and energy dissipation and decrease in the residual displacement [8]. Other studies have shown that Steel Fiber-Reinforced Concrete (SFRC) can help increase the shear strength, deformation, and energy absorption capacities of reinforced * Corresponding author. E-mail addresses: julian.carrillo@unimilitar.edu.co (J. Carrillo), jose.pincheira@wisc.edu (J.A. Pincheira), lfc@cenapred.unam.mx (L.E. Flores). Contents lists available at ScienceDirect Journal of Building Engineering journal homepage: http://www.elsevier.com/locate/jobe https://doi.org/10.1016/j.jobe.2019.100975 Received 1 February 2019; Received in revised form 30 September 2019; Accepted 2 October 2019