Engineering Structures 227 (2021) 111411 Available online 4 November 2020 0141-0296/© 2020 Elsevier Ltd. All rights reserved. In-plane shear strengthening of brick masonry panel with geogrid reinforcement embedded in bed and bed-head joints mortar Biplab Behera * , Radhikesh Prasad Nanda Department of Civil Engineering, NIT Durgapur, Durgapur 713209, India A R T I C L E INFO Keywords: Brick Geogrid Mortar joint reinforcement In-plane shear ABSTRACT An experimental investigation was carried out to study the strengthening performance of brick masonry prisms and panels via geogrid reinforcement embedded in brick mortar. A compressive strength test was performed for brick prisms, while a diagonal compression test was performed for brick panel with two patterns, i.e., geogrid reinforcement at bed joints as well as at bed-head joints. The compressive strength of the geogrid embedded prisms was found to be 32.65% more than that of un-reinforced brick prisms. While, geogrid-reinforced brick panels exhibited better crushing load, in-plane shear strength, lateral strength, ductility, etc., than un-reinforced masonry with the highest in-case of bed joint reinforcement. Cost analysis showed that the unit costs of un- reinforced and reinforced walls are similar (within 6.5%). Thus strengthened walls can be valid alternative to un-strengthened walls for new constructions and a low-cost strengthening technique for earthquake disaster mitigation of brick masonry buildings. 1. Introduction Masonry is the major form of building structures for habitation in developing countries. It has innumerable advantages, including thermal insulation, sound resistivity, the option of addition and alteration after construction, less formwork, easy and low-cost repair, use of local and eco-friendly materials, need of less-skilled labor, and less engineering intervention over other present day reinforced concrete and steel con- struction. Masonry buildings are constructed via a combination of non- engineered bricks and mortar. Bricks have good compressive strength, perform well under gravity loading, and act vertically on the structures. However, such unreinforced brittle structures are not strong enough for resisting lateral thrust generated due to earthquake ground motion; hence, they cause major hindrance in seismically active regions. The history of past earthquakes has resulted in maximum damages to structures and has also accounted for the maximum loss of lives and properties. Moreover, feld surveys of past earthquake-affected areas (Bhuj, 2001; Bam, 2003; Kasmir, 2005; Sichuan, 2008; Haiti, 2010; Gorkha, 2015) have demonstrated that the collapse of low-strength masonry dwellings is mainly responsible for the loss of lives and prop- erties. Hence, it is a challenging job for the engineering community to improve the shear and tension-carrying capacity of masonry dwellings for mitigating earthquake-induced effects. During an earthquake, masonry fails mainly due to in-plane shear and out-of-plane bending [1,2]. The structural walls in the direction of seismic motion are subjected to in-plane forces, while the cross walls are subjected to out-of-plane bending. However, the behavior of masonry walls due to in-plane loading depends on gravity loads, geometry of walls (height/length ratio), boundary conditions, and mechanical properties of masonry constituents. Masonry piers subjected to in-plane horizontal loading may face fexure or rocking mode of failure, sliding shear mode of failure, and diagonal shear mode of failure [3–6]. Rocking failure is associated with slender pier with wick compressive loads. Here, the horizontal load causes lifting with tensile fexural cracks at the heel side of the pier, while the toe side is subjected to compressive (crushing) failure (Fig. 1a). In the case of low vertical compressive stress in the wall and poor quality of mortar, in-plane forces may cause the sliding of a part of the wall along one of the bed-joints (Fig. 1b). How- ever, the diagonal shear failure may occur when the principal tensile stresses on the wall due to horizontal and vertical loads exceeds the tensile strength of masonry, leading to diagonal cracks (Fig. 1 b). Diagonally oriented cracks may either follow the bed- and head- joints or pass through the units or partly follow the joints and partly pass through the units (Fig. 2). ElGawady et al. [2] used a steel mesh around the building’ s exterior surfaces, followed by its coating with a layer of high-strength mortar. Cracks were sealed with cement-sand mortar grout, followed by the * Corresponding author. E-mail address: bb.18ce1104@phd.nitdgp.ac.in (B. Behera). Contents lists available at ScienceDirect Engineering Structures journal homepage: www.elsevier.com/locate/engstruct https://doi.org/10.1016/j.engstruct.2020.111411 Received 14 February 2020; Received in revised form 14 September 2020; Accepted 4 October 2020