Recent Advances in Wave Travel Time Based Methodology for Structural Health Monitoring and Early Earthquake Damage Detection in Buildings

Recent advances in the development of a wave travel time methodology for earthquake damage detection in buildings, for use in rapid assessment of structural health following an earthquake, are reviewed. Its main advantages over the modal methods are the insensitivity to the effects of soil-structure interaction, local nature, and robustness when applied to real structures and strong earthquake response. Three algorithms are reviewed, which identify wave velocity profiles of vertically propagating shear and torsional waves through the building by fitting a layered shear beam/torsional shaft model in observed building earthquake response, and a selection of results of their application to three buildings: Los Angeles 54-story office building (steel), Millikan Library in Pasadena (RC), and Sheman Oaks 12-story office building (RC), damaged by the San Fernando earthquake of 1971. The appropriateness of the model for different types of buildings, and the accuracy of the identification are discussed.