Damage detection in asymmetric buildings using vibration-based techniques

In recent times, esthetic and functionality requirements have caused many buildings to be asymmetric. An asymmetric building can be defined as one in which there is either geometric, stiffness, or mass eccentricity. Such buildings exhibit complex vibrations as there is coupling between the lateral and torsional components of vibration and are referred to as torsionally coupled buildings. These buildings require 3-dimensional modeling and analysis. Despite recent research and successful applications of damage detection techniques in civil structures, assessing damage in asymmetric buildings remains a challenging task for structural engineers. There has been considerably less investigation on the methodologies for detecting and locating damage specific to torsionally coupled asymmetric buildings. This paper develops a multicriteria approach using vibration-based damage indices for detecting and locating damage in asymmetric building structures. These vibration indices are based on the modified versions of the modal flexibility and the modal strain energy methods. The proposed procedure is first validated through experimental testing of a laboratory scale asymmetric building model. Numerically simulated modal data of a larger scale asymmetric building obtained from finite element analysis of the intact and damaged asymmetric building models are then applied into the modified modal flexibility and modal strain energy algorithms for detecting and locating the damage. Results show that the proposed method is capable of detecting both single and multiple damages in the beams and columns of asymmetric building structures.