FREQUENCY BASED DAMAGE DETECTION OF INFILL WALL RCC BUILDINGS

Abstract

Structural health monitoring of reinforced concrete buildings with infill walls is critical for ensuring safety in seismically active regions. In this study, a frequency based damage detection approach is employed to assess the integrity of infill wall RCC structures. The presence and extent of damage are identified by analyzing shifts in natural frequencies, which are sensitive indicators of stiffness degradation. Micro tremor was used to identify the ambient vibration data of 29 undamaged healthy buildings in Madhyapur Thimi. Time domain data collected by Micro tremor were transferred into frequency domain by Fast Fourier transform (FFT) method. This study explores a frequency-based approach for identifying damage in Reinforced Cement Concrete (RCC) buildings with infilled walls. Analytical modeling techniques such as Finite Element Method (FEM) was used to simulate damage scenarios and correlate them with frequency shifts. The approach aims to provide a non-invasive, efficient, and reliable method for early detection of structural damage. The empirical relation between buildings height and time period was developed with regression analysis which can be later be used to find out natural time period of undamaged buildings. The natural time period of undamaged or healthy buildings changes after earthquake. In this study, four multi bays and four single bay buildings were analyzed which are most common in our locality for the nonlinear pushover analysis. The empirical relation between rate of percentage change of time period versus percentage drift was developed from nonlinear pushover analysis. Extent of percentage change in drift is categorized with different damage states (HRC scale) from the above developed relation.