Health Monitoring for Civil Infrastructure

Internet technologies are increasingly facilitating real-time monitoring of Bridges and Highways. The advances in wireless communications for instance, are allowing practical deployment for large extended systems. Sensor data, including video signals, can be used for longterm condition assessment, traffic-load regulation, emergency response, and seismic safety applications. Computer-based automated signal-analysis algorithms routinely process the incoming data and determine anomalies based on pre-defined response thresholds. Upon authentication, appropriate action may be authorized for maintenance, early warning, and/or emergency response. In such a strategy, data from thousands of sensors can be analyzed with realtime and long-term assessment and decision-making implications. Addressing the above, a flexible and scalable (e.g., for an entire Highway system, or portfolio of Networked Civil Infrastructure) software architecture/framework is being developed and implemented. This framework will network and integrate on-line real-time heterogeneous sensor data, database and archiving systems, computer vision, data analysis and interpretation, numerical simulation of complex structural systems, visualization, probabilistic risk analysis, and rational statistical decisionmaking procedures. Such a decision-support system contributes to the vitality of our economy, as rehabilitation / renewal / replacement / maintenance of this infrastructure is estimated to require expenditures in the Trillion-dollar range nationwide (in addition to Homeland security/natural disaster concerns). An evolving project portal (http://healthmonitoring.ucsd.edu) currently depicts some elements of the envisioned integrated health monitoring analysis framework. CONDITION OF CIVIL INFRASTRUCTURE The deterioration of the civil infrastructure in North America, Europe and Japan has been well documented and publicized. In the United States, 50 percent of all bridges were built before the 1940's and approximately 42 percent of these structures are structurally deficient. Since the occurrence of the 1994 Northridge, California, earthquake and the 1995 Kobe, Japan, earthquake, there has been a quantum jump in the number of civil structures that have been instrumented for monitoring purposes. Furthermore, plans are underway to install a variety of strong-motion vibration sensors in many civil structures (in some cases many hundreds of sensors in a single structure). Clearly, the main issue that is facing the structural health monitoring community is not the lack of measurements per se, but rather how to measure, acquire, process, and analyze the massive amount of data that is currently coming on-line (not to mention the terabytes of streaming data that will inundate potential users in the near future) in order to extract useful information concerning the condition assessment of the monitored structures.