Wave Method for Structural Health Monitoring and Damage Detection in Bridges

In this project, we will apply, for the first time, the wave method to bridge structures to monitor their structural integrity and to detect their extent of damage soon after a destructive event (e.g., earthquakes). The wave methodology has been developed and tested by author and his colleagues in the past ten years for buildings’ post-disaster (e.g., earthquake or blast) damage detection and degradation study. In this project, we extend the application of the method, which was shown to be successful in detecting damage in buildings, to bridge structure. This study will help in evaluating the performance of the method on the bridge structures, identifying challenges compared to buildings and ultimately, enhance the method to be used as a robust and state-of-the-art damage assessment technique for bridges subjected to natural or manmade disasters. 

A robust interferometric method for structural health monitoring (SHM) and damage detection of buildings during earthquakes utilizing data from seismic sensors (e.g., accelerometers) will be further developed to be applied to highway bridges and overpasses. This SHM method is intended to be used in automated seismic alert systems, to issue a warning of damage to the bridge during or immediately after an earthquake or other manmade disasters (e.g., blast or large vehicle impact). Availability of a robust SHM algorithm would facilitate decision making on closure of an affected bridge, to avoid loss of life and injury caused by possible collapse of the weekend structure during aftershock shakings or service traffic load. 

The method identifies a wave velocity profile of the structure by fitting an equivalent layered shear beam model in impulse response functions of the recorded earthquake response. The structural health is monitored by detecting changes in the identified velocities in moving time windows or among multiple events. It was shown in previous studies by author (for buildings) that the wave method has important advantages over vibrational methods including: a) Not being sensitive to the soil-structure interaction effects, b) ability to localize damage in the structure, and c) robust when applied to real structures and large amplitude motion. 

The applicability of the method for bridges will be investigated and further calibrated utilizing sensory data from a shake-table 4-span prototype bridge tested to failure in the University of Nevada Reno (UNR) in 2007 (NSF #0420347) [13]. Availability of data from this project provides a unique opportunity to calibrate our developed methodology for bridges and to further assess the strength, accuracy and limitations of it as a post-event decision-making tool.

Principal Investigator: 

Mehran Rahmani, Ph.D., P.E.

PI Contact Information: 

mehran.rahmani@csulb.edu 
California State University, Long Beach

Project Number: 

1934