In-plane and out-of-plane testing of unreinforced masonry walls strengthened using polymer textile reinforced mortar Najif Ismail a,⇑ , Jason M. Ingham b a Department of Civil & Environmental Engineering, United Arab Emirates University, PO Box 15551, Al Ain 1818, United Arab Emirates b Department of Civil & Environmental Engineering, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand article info Article history: Received 23 November 2011 Revised 16 March 2016 Accepted 16 March 2016 Keywords: Seismic strengthening Structural testing In-plane Out-of-plane Brick masonry Polymeric composites Polymer textile abstract Details of an experimental program investigating the structural performance of unreinforced masonry (URM) walls strengthened using two different types of polymer textile reinforced mortar (TRM) is pre- sented. The experimental program involved full scale reversed cyclic in-plane and out-of-plane testing of TRM strengthened URM walls. The testing was performed in two series, with series 1 involving in- plane testing of two (03) pier-spandrel assemblages representing part of a perforated URM wall and ser- ies 2 involving out-of-plane testing of three (03) slender walls having no penetrations. To replicate the physical characteristics of historic masonry materials, vintage solid clay bricks and a low strength hydraulic cement mortar were used for construction of the test walls. Numerous structural characteris- tics pertaining to the seismic behaviour of TRM strengthened historic URM walls were investigated and then compared to those obtained from corresponding as-built tested URM walls. In general, strengthened walls exhibited a ductile behaviour until the polymer textile ruptured in a brittle manner. The strength increment due to TRM strengthening was observed to range from 128% to 136% when the URM test walls were loaded in-plane and from 575% to 786% when the URM test walls were loaded out-of-plane, with a notable increment in deformation capacity and ductility. Ó 2016 Elsevier Ltd. All rights reserved. 1. Introduction Unreinforced masonry load bearing (URM) walls have routinely been documented to exhibit poor seismic performance during moderate to severe earthquakes, resulting in partial or complete collapse of the building [1–5]. The observed poor seismic perfor- mance of URM buildings has highlighted the seismic hazard asso- ciated with this form of construction, and the need for further investigation to advance the understanding of aspects related to their seismic assessment and improvement. In the event of an earthquake, gravity loaded URM walls are also subjected to lateral loading either oriented parallel (referred to as in-plane load actions) or oriented perpendicular (referred to as out-of-plane load actions) with respect to their stronger plane, or the URM wall may be subjected to a combination of both lateral load actions. The seismic behaviour of in-plane loaded perforated URM walls (also referred to as URM equivalent frames) is explained by delineating these walls into separate spandrel, joint, and pier elements. Spandrels and piers have been observed to undergo damage more frequently than the joint regions [6], with the failure of pier and spandrel elements being either flexural controlled or shear controlled (or a combination of both). The flexural controlled failure mode is characterised by horizontal cracking at pier tops and bases, flexural vertical cracks at pier-spandrel interfaces, and/or compression crushing at plastic hinge locations (i.e. toe region of piers) that results due to rocking of piers. Sliding along a mortar joint (step joint or bed joint) or diagonal cracking through bricks [7], in either spandrels or piers, are the two most frequently noted shear controlled failure modes in URM frames. Likewise, face-loaded slender URM walls are prone to partial or complete out-of-plane collapse during earthquake, which can result due to flexural failure of the wall and/or wall anchorage failure [8]. Assuming the presence of adequate wall-diaphragm anchorages to provide sufficient lateral restraint, out-of-plane lateral loading causes bending in the wall and depending upon the specifics of the boundary restraints leads to either one-way or two-way bend- ing. Typically, slender historic URM walls with height to thickness ratios greater than 14 are prone to out-of-plane failure when deforming in a one way bending mode [9,10]. A number of seismic strengthening techniques have been implemented in the past to improve the seismic performance of http://dx.doi.org/10.1016/j.engstruct.2016.03.041 0141-0296/Ó 2016 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail addresses: najif@uaeu.ac.ae (N. Ismail), j.ingham@auckland.ac.nz (J.M. Ingham). Engineering Structures 118 (2016) 167–177 Contents lists available at ScienceDirect Engineering Structures journal homepage: www.elsevier.com/locate/engstruct