Rational Analysis Design of Low Rise and High Rise Building with Storey

Abstract

The fundamental design concept of earthquake resistance design of structures is to have weak beam-strong column system to ensure safety of users by letting beams yield before columns collapse during an earthquake. Many buildings that collapsed during the past earthquake exhibited exactly the opposite strong beam-weak column behavior - columns failed before the beams yielded due to soft storey effect. The buildings with soft storey are very vulnerable under lateral loads and that creates disasters. One of the major problems in present days is severe shortage of parking space in multistorey buildings. Due to accommodation of vehicles and their movements at ground levels infill walls are generally avoided, which creates soft storey effect. It should be noted that 70 to 80 % of buildings of urban areas in India fall under the classification of soft storey according to IS 1893 (2002) Part-I. For proper assessment of the storey stiffness of such buildings, considerations of infill walls with moment resisting frame is essential. A method of modelling of infills in moment resisting frame is studied. Evaluation of the storey stiffness of low rise and high rise building considering various models like bare frame, bare frame with tie beams, frame with infills and frame with infills and tie beams is presented in thesis. The attempts are made to enhance the stiffness of soft storey considering functional requirements of that storey. In case of high rise building, various options like (1)provision of infill walls in soft storey region (2) provision of squat v wall in soft storey region (3) provision of shear wall at proper location in building are studied. For low rise building, design of structural member of soft storey is done by capacity design concept , in which deterministic allocation of strength to structural element is carried out to achieve desirable hierarchy in the failure mode of the structure. A sincere effort is undertaken for critical study of clause 7.10.3 (a) and 7.10.3 (b) related to soft storey of IS 1893- (2002) Part I.