BRIGE: Robust Signal Processing Algorithms for Health Monitoring of Civil Infrastructure Subjected to Seismic Loads

This material is based upon work supported by the National Science Foundation under Grant Number 1121146

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Abstract

This Broadening Participation Research Initiation Grant in Engineering (BRIGE) provides funding for the development of a model-free signal-processing-based methodology for rapid damage detection in civil structures subjected to earthquake excitations. Advanced mathematical techniques for the analysis of nonlinear-nonstationary signals will be engaged to develop algorithms capable of identifying the occurrence and severity of damage from examination of the structural response. Initial validation and calibration of the algorithms will be performed using state-of-the-art nonlinear structural models that utilize fiber-based distributed plasticity elements capable of replicating the structural members' actual nonlinear hysteretic response including different types of failures. Small scale shaking table tests will be performed to further validate the algorithms developed. The educational and broadening participation activities aim to increase the participation of underrepresented groups in engineering. Such activities include shake table based structural design competitions/demonstrations at underserved pre-college schools in Puerto Rico and the development of a practicum course in signal processing and data analysis.

If successful, the results of this research will lead to improvements in the implementation of real-time structural health monitoring systems. This will have a direct positive impact in the coordination of post-earthquake emergency responses by local authorities. While the research program is designed to tackle the early damage detection problem in civil structures subjected to seismic loads, the fundamental knowledge developed will have an impact in any engineering or scientific discipline dealing with signal processing, data analysis, target/anomaly detection, damage simulation or health monitoring. The interdisciplinary nature of the research presents unique learning opportunities to our undergraduate and graduate students. The outreach activities will impact a large number of Hispanic pre-college students through the University of Puerto Rico Science on Wheels Educational Center.

Outreach and educational material

Workshop on nonlinear modeling of reinforced concrete structuresusing OpenSees: This is a 2 day hands-on workshop offered to graduate and senior students at UPRM. The Open System for Earthquake Engineering Simulation (OpenSees) is a software framework for simulating the seismic response of structural and geotechnical systems. OpenSees has been developed as the computational platform for research in performance-based earthquake engineering at the Pacific Earthquake Engineering Research Center and is also the simulation component for the NEESit. Despite OpenSees powerful capabilities for modeling and analyzing the nonlinear response of systems, the program may seem overwhelming at first glance for the inexperienced user. The objective of the workshop is to foster the use of OpenSees in research projects at UPRM by giving the students a head start in the use of the program. The examples provide include the tcl source files, experimental data for model verification/calibration and simple Matlab codes to post-process the data.

K-12 outreach program: This is a 2 day outreach activity intended for high school students. The students have the opportunity to design, build and test a multistory building made of k-next elements. The building is tested at different levels of earthquake intensities using an educational shake table.

“Introducción a la dinámica de estructuras” (in Spanish): Adaptation and translation of the educational module developed by the University Consortium on Instructional Shake Tables (UCIST)

“Identificación de propiedades dinámicas usando wavelets” (in Spanish): A new shake table based educational module (integrated into the Practicum in Signal Processing and Data Analysis course).

Publications produced as a result of this research

Gaviria, C.A. and Montejo, L.A., “System Identification of Civil Structures using the Mass Response Method and Simultaneous Time-Frequency Analysis,” EERI Annual Meeting (Poster Section), Seattle, WA, February 2013 [pdf]

Aguirre, D.A. and Montejo, L.A., “Damping and Frequency Changes Induced by Increasing Levels of Seismic Inelastic Demand On Reinforced Concrete Structures,” EERI Annual Meeting (Poster Section), Seattle, WA, February 2013 [pdf]

Aguirre, D.A., Gaviria, C.A. and Montejo, L.A. “Wavelet Based Damage Detection in Reinforced Concrete Structures Subjected to Seismic Excitations,” Journal of earthquake Engineering, accepted for publication. [preprint, pdf]

Montejo, L.A and Vidot, A.L., “Synchrosqueezed Wavelet Transform for Frequency and Damping Identification from Noisy Signals,” Smart Structures & Systems, Vol. 9, No. 5, 2012 [preprint, pdf]

Montejo, L.A. “Modal Frequencies and Damping Identification via Synchrosqueezed Wavelet Transform.” International Conference on Earthquake Engineering Research Challenges in the 21st Century, Harbin, China, 2012 [pdf]

Ramirez-Castro, R.I.; Montejo, L.A.. "Hilbert Transform, Empirical Mode Decomposition and its Applications to Free Vibration Analysis (in Spanish)," Revista Internacional de Desastres Naturales, Accidentes e Infraestructura Civil, v.11 (2), 2011, p. 123 [pdf]