CHAUDHRY, CHARU1;

1) Project Director, Thornton Tomasetti, Inc, Building Performance, cchaudhry@thorntontomasetti.com

Damage to unreinforced brick masonry buildings is often caused by stresses due to thermal expansion, contraction, moisture movement and settling. The deterioration includes cracks through brick walls, separation of the multiple wythes and collapse of the wall. Unstable environments are created within the masonry due to variations in ambient temperature, changes in loads and loading patterns due to continual processes of expansion and contraction. The injection of binding materials is one of the techniques used for improving the mechanical characteristics of the existing masonry walls. As unreinforced buildings without any design allowance to accommodate freeze-thaw or thermal cycles, age, they develop cracks along the weak planes. Investigation at Terminal Warehouse Company Central Stores Building built in 1890 revealed extensive cracking along the characteristic arches and windows of the facades and bulkheads. By strengthening the structure using grouts, the threshold of lateral force at which the damage initiates, can be increased at the macro level, leading to improvement of the overall quality of the cracked masonry walls. It provides for the inertia forces generated by the vibration of the building to be transmitted to the members that have the ability to resist them. This imparts stiffness and creates a uniform behavior of the structure. Strength enhancement through homogeneity of the material largely depends on the “compatibility” of the injected and the parent materials. The idea of grouts is to use a material with more cohesion than the parent masonry achieved by materials with good binding properties and a minimal tensile strength.

Keywords: unreinforced masonry buildings, grouting, strengthening