Strength comparison of masonry wall made of clay burnt brick with frog mark and machine made brick without frog mark

Abstract

ABSTRACT

Compressive strength, shear strength and Modulus of elasticity of masonry are significant parameters when considering structural masonry design. For simulation of structural behavior of masonry buildings, performance of embedded joint is important from the point of view of seismic design. Masonry structures of Bangladesh are mostly designed for vertical loads. The structural elements such as walls which were designed for vertical loads only, have to carry lateral load as well during an earthquake. Important masonry parameters are compressive strength, flexural strength, shear strength, modulus of elasticity etc. An attempt has been made in this study to correlate compressive strength, shear strength and wall stiffness, for clay burnt bricks with frog mark and machine made bricks without frog mark. In this experimental study, eight prisms and eight (10") URM wall specimens with a size of 5 × 3 were constructed with two different types of bricks, i.e clay burnt brick with frog mark and machine made brick without frog mark. Two types of mortar thicknesses 1/2" and 3/4" were used in the test specimens. The prism specimens were tested under axial compression normal to the bed joints and the wall specimens were tested under horizontal incremental cyclic loading along with constant axial compressive load. Lateral loading was applied using a loading control pattern. The specimens were tested under cyclic loading conditions displacing them laterally, along the axis of the walls and their load-deformation behavior was measured by dial gauges. It is observed that, increasing mortar thickness prism ultimate strength increases 18.0% for clay burnt brick and with increasing mortar thickness prism ultimate strength increases 1.3% for machine made brick. On the other hand, with the increasing mortar thickness ultimate shear strength decreases 9.6% for clay burnt brick with frog mark and with increasing mortar thickness ultimate shear strength decreases 8.0% for machine made bricks without frog mark. In clay burnt brick shear strength is 12.5% more than machine made brick. Increasing mortar thickness ductility decreases 22.0% for clay burnt brick and 20.0% for machine made bricks.