COMPARING SEISMIC RESPONSE OF SOFT-STOREY STRUCTURE WITH AND WITHOUT BRACINGS

MohdAliuddin, Mohammed ShoaibAyjaz, VenkataDilip Kumar Pasupuelti

Abstract: In general, multi-storey buildings in metropolitan cities require open taller ground storey for parking of vehicles owing to lack of horizontal space and high cost. Due to this functional requirement the first storey has lesser strength and stiffness as compared to upper stories, which are stiffened by masonry infill walls. This characteristic of building construction creates “weak” or “soft” storey problems in multi-storeyed buildings. Increased flexibility of first storey results in extreme deflections which in turn, lead to concentration of forces at the second storey connections accompanied by large plastic deformations. In addition most of the energy developed during the earthquake is dissipated by the columns of the soft stories. In this process the plastic hinges are formed at the ends of columns which transform the soft storey into a mechanism. In such cases the collapse is unavoidable. Therefore the soft stories deserve a special consideration in analysis and design. A case study of a building located in Hyderabad which falls under the Seismic Zone II, is considered to show how the response of a soft storied building during an earthquake changes when it is provided with diagonal struts only at the corners bays of the soft storey. Since struts are being provided at the corners, they do not interfere significantly with the desired functionality of the soft storey. The aim of this paper is mainly to analyze the feasibility of this solution as the configuration of the building varies in different directions

Keywords: Softstorey, dynamic analysis, bracings, time history analysis

DOI: https://doi.org/10.15623/ijret.2015.0425033