A refined Frequency Domain Decomposition tool for structural modal monitoring in earthquake engineering

Output-only structural identification is developed by a refined Frequency Domain Decomposition (rFDD) approach towards assessing current modal properties of heavy-damped buildings (in terms of identification challenge), under strong ground motions. Structural responses from earthquake excitations are taken as input signals for the identification algorithm. A new dedicated computational procedure, based on coupled Chebyshev Type II bandpass filters is outlined for the effective estimation of natural frequencies, mode shapes and modal damping ratios. Also, the present identification technique is coupled to a Gabor Wavelet Transform, by resulting in an effective and self-contained timefrequency analysis framework. Synthetic response signals generated from shear-type frames (with variable structural features) are adopted as a necessary validation condition. In this context, use is made of a complete set of seismic records coming from the FEMA P695 database, i.e. all 44 “Far-Field” (22 NS, 22 WE) earthquake signals. The achieved modal estimates are statistically compared to the target values, proving the accuracy of the developed algorithm in providing prompt and accurate estimates of all current strong ground motion modal parameters. At this stage, such analysis tool may be employed for convenient application in the realm of Earthquake Engineering, towards potential Structural Health Monitoring and damage detection purposes.