Flexural strength of unreinforced lattice masonry walls subjected to lateral out-of-plane loading

Lattice masonry is a form of construction in which the mortar perpend joints are left unfilled and the masonry units are spaced along the courses to leave gaps between adjacent units. When designing such walls to resist out-of-plane lateral loading due to wind and/or earthquake actions, the Australian Standard AS3700: Masonry Structures provisions for one way vertical bending can be applied by using a section modulus based on the net bedded area. However, the provisions for horizontal bending require that the masonry be constructed with all perpends completely filled and therefore lattice masonry falls outside the scope of AS3700 for horizontal bending. The paper describes a preliminary study to assess the behaviour of unreinforced lattice masonry walls subjected to lateral out-of-plane pressure loading. Six lattice masonry panels, 14 courses (1194 mm) high x 4 units with 90 mm gaps (1190 mm) long, were constructed using extruded clay bricks (230 mm long x 110 mm wide x 76 mm high) and 1:1:6 (cement : lime : sand) mortar. Three panels were tested in one way vertical bending and three were tested in one way horizontal bending. The load versus deformation behaviour and the observed failure modes are reported. The AS3700 provisions for solid masonry were used to predict the panel strengths and an assessment of the suitability of the provisions for the design of lattice masonry is made.