Ambient vibration testing of existing buildings in Surat city

Abstract

Day by day the popularities of apartment structure systems are increasing in India instead of load bearing structures and typical frame structures. The design of such structures gains more exposure, particularly for the equal static analysis, precise time calculations are essential [1]. Very few numbers of codes are available in India to calculate dynamic properties of structures for seismic design. According to Indian Standards, the approximate fundamental natural period of building can be calculated based on Height and width of Structure. But no specification or equations are available about effect of Structure age on Natural Period of structure and Number of storey’s in Indian Standards. During the assessment of a structure and its construction method, calculations and/or assessments of its fundamental frequency are crucial. [2]. Buildings of Surat City selected for survey based upon number of storeys, type and age of structures. Microtremor record was taken for 30 minutes for each storey in each selected building. After obtaining Microtremor records, random discrete technique was performed to estimate relevant characteristics. An approximately 20-25% reduction found in Amplifications at terrace level of each structure due to reduction in storey stiffness and mass at terrace level. Also from the data analysis, the frequency of structure increases with increase in age of structure due to increment in brittleness of building material with passing days.