Mahmoud El Rayes1 and Nigel Shrive2
1) Research Associate, Department of Civil Engineering, National Research Centre
Dokki, Cairo, Egypt, 12622
2)  Professor, Department of Civil Engineering, University of Calgary,
Calgary, AB, Canada, T2N 1N4

Keywords: Multi-wythe masonry, Transverse ties, Experimental tests, Strengthening, Rehabilitation

Abstract. Ties were inserted transversely across multiwythe walls to determine if the compressive strength of a wall and its ability not to separate in-plane between the wythes was improved. The walls consisted of outer wythes of brickwork separated by a grouted core. Some walls had Carbon Fibre Reinforced Polymer rebar ties installed before testing, whereas other walls were tested and cracked before installing the ties, then re-tested. Installing ties directly across walls at regular intervals and constant density was not efficient, providing minimal benefits. Bars were also inserted in groups to resist the diagonal cracking expected from the in-plane lateral loading. These connectors were subject to tension, compression, bending and, shear based on their orientation, location in the wall and the applied loading. In cases of eccentric loads or different materials in the external wythes, the ties bent slightly producing internal stresses, with no apparent change in wall behaviour. Ties were also arranged in 3-D to produce semi-continuous elements. Such elements produced higher lateral forces and stiffness in damaged walls compared to a plain wall. Also, the energy dissipated was higher than during the initial test, implying the development of a new set of cracks. The experimental program and major findings with respect to orientation of anchors to improve resistance and wall integrity under in-plane shear are described.