Bridge Instrumentation and Monitoring for Structural Diagnostics

Abstract

Diagnostic instrumentation and monitoring of bridges are essential for reliable structural condition assessment and performance evaluation. This management step applies particularly to structurally deficient bridges that cannot be accurately evaluated by inspection and/or analysis alone. Reliable evaluation is an economic and engineering requirement before any decision-making for preventive action. Thus, field diagnostic capabilities are indispensable tools to enable evaluation and support field-calibrated modeling, analysis, identification, and load rating. The reliability of structural evaluation for objective bridge management is determined by the dependable performance of all the system components. Although instrumentation and monitoring procedures appear to be well established, some misconceptions still keep recurring critically in practice. To improve the state-of-practice of structural diagnostics, available field systems and methods need re-evaluation of their instrumentation and monitoring performance under real-world conditions. Subsequently, dedicated field capabilities can be formulated and developed to have advanced and practical characteristics. This article discusses various less-emphasized critical aspects of multidisciplinary research experience on bridge structural health monitoring, to explore dependable evaluation methods, compile practical data on actual bridge monitoring for immediate implementation, and generate focused insight for the development of advanced, reliable, and practical research methods in the future. To reach a systematic conceptualization for a better methodology, various diagnostic components are criticized. The resulting discussions on the various bridge evaluation aspects are practical for transportation agencies, bridge officials, and researchers. The detailed aspects are intended to help select appropriate implementation practices in field applications of bridge instrumentation and monitoring. These help focus bridge management policies, re-orient evaluation strategies, and reconsider diagnostic methods.

Development of a structural health monitoring system for the life assessment of critical transportation infrastructure.

“…Another significant problem is the tendency of gauges placed on a structure to experience random drift, which over time, can make the readings from a sensor useless (Farhey 2005). Data storage and processing becomes an issue for large structures in cases where many sensors are read on a continuous basis and/or readings are taken at a high frequency.…”

“…Once the data was gathered and the model for each bridge calibrated, the remaining fatigue life of the structures could be estimated and the probability of an overload could also be predicted (Tobias and Foutch 1995). Farhey (2005) discusses the usefulness of SHM technology to reliably determine the condition of the structures under investigation and how prognostic bridge management should be the ultimate goal. Farhey (2005) also discussed the shortcomings of long-term monitoring of bridges including the fact that many sensor types require periodic recalibration.…”

“…Farhey (2005) discusses the usefulness of SHM technology to reliably determine the condition of the structures under investigation and how prognostic bridge management should be the ultimate goal. Farhey (2005) also discussed the shortcomings of long-term monitoring of bridges including the fact that many sensor types require periodic recalibration. In the literature, there did not appear to be any bridge management software that incorporates a fatigue model along with a damage model for the aging of the structural materials.…”

Modal Analysis for the Rehabilitation Assessment of the Luiz I Bridge

“…Consequently, the use of nondestructive testing tools is emerging as a valuable solution to assist in the condition assessment of existing structures, both in terms of their load-carrying capacity and serviceability (DeWolf et al 2002). Moreover, data obtained through these means are essential for the quantification of parameters and identification of mechanisms that are to be integrated in the numerical models that support reliable and objective structural evaluation (Farhey 2005). In this context, model calibration based on experimental measurement emerges as a key task, for which the selection of the model space and strategy for the numerical modeling and physical completeness are the kernel problems (Aktan et al 1998).…”

“…Although some researchers have pointed out the intrinsic difficulties in performing vibration testing in large bridges, such as nonstationary excitation (Catbas et al 2007), nonlinear boundary or continuity conditions, and nonideal connections/interfaces between structural members and components (Farhey 2005), it is unquestionable that dynamic testing stands as an innovative way of great potential in the structural identification of bridges for condition assessment (Aktan et al 1997;DeWolf et al 2002). It becomes imperative when assessing the seismic vulnerability of a structure and corresponding retrofit design (Cheung et al 2007), and can play a decisive role in the rehabilitation of centenary steel bridges, both in supporting the project design and validating their performance for the new structural condition.…”