Study On Dynamic Behaviour of Engineering AAC Block Building

Abstract

Masonry, either Brick or Stone, is the most widely accepted material for construction of Building and Monumental structures, since age old. This is primarily attributed due to local availability of the materials, in abundance. However, building built through Brick or Stone materials become massive and stiff. Such acceleration sensitive buildings attract huge Inertia force in the event of an earthquake and makes them vulnerable. Thus, Stone Masonry structure limits to the rural areas of the country while Brick Masonry buildings are being replaced by Reinforced Concrete (RC) Frame with non-structural Brick infill panels, in urban areas. Recently, modern construction technology leading towards high-rise RC buildings seen accelerated use of Autoclaved Aerated Concrete (AAC) block masonry infill instead of brick masonry infill. AAC block masonry offers almost half the density as compared to brick masonry and hence reduces the mass of the structure. Additionally, size of AAC block makes construction of infill panel simpler and faster. In the present major project work, potential of engineered AAC block masonry building is explored against conventional brick masonry building through dynamic test. Dynamic behaviour of AAC block masonry building built through Half-block Joint (English Bond) and Full-block Joint (Normal/ Stretcher Bond) are studied first. Learning from types of damage suffered by engineering AAC Block masonry building retrofitting strategies for the said models are evolved referring appropriate clauses of Indian standards IS:1905- 1987, IS:4326-2013 and IS:18935-2009. Two engineered AAC block masonry building retrofitted in terms of Sill Band, Lintel Band, Corner wire reinforcement and seismic belt are prepared to conduct experiment. Building models for both tests are instrumented with Uni-axial Accelerometers, Data Acquisition System and Computer System to record acceleration response of building models under freely falling pendulum importing short time period impulse of varied input energy. A damage caused to building models due to shock loading are observed and useful conclusions are derived. Similar to Brick masonry building, AAC block masonry building models, when subjected to shock loading, shows severe damage in the walls perpendicular to the direction of shock. Apart, partial collapse to complete collapse of the both models (with English and Stretcher bond) are observed. However, Building models retrofitted with Bands, Corner Reinforcement and Seismic belt do not collapse under dynamic loading. Retrofitted Building shows heavy damage to the building for high input energy. Thus, AAC block masonry building offers a potential alternative to Brick masonry Building for seismically active regions.