A fiber optic structural health monitoring (SHM) system was developed and deployed by the Iowa State University
(ISU) Bridge Engineering Center (BEC) to detect gradual or sudden damage in fracture-critical bridges (FCBs). The
SHM system is trained with measured performance data, which are collected by fiber optic strain sensors to identify
typical bridge behavior when subjected to ambient traffic loads. Structural responses deviating from the trained behavior
are considered to be signs of structural damage or degradation and are identified through analytical procedures similar to
control chart analyses used in statistical process control (SPC).
The demonstration FCB SHM system was installed on the US Highway 30 bridge near Ames, IA, and utilizes 40 fiber
bragg grating (FBG) sensors to continuously monitor the bridge response when subjected to ambient traffic loads. After
the data is collected and processed, weekly evaluation reports are developed that summarize the continuous monitoring
results. Through use of the evaluation reports, the bridge owner is able to identify and estimate the location and severity
of the damage. The information presented herein includes an overview of the SHM components, results from laboratory
and field validation testing on the system components, and samples of the reduced and analyzed data.
Owners must manage and ensure the safety of their civil structures even as use of many structures extends well beyond their design lifetime. Traditionally, most structures rely on strict maintenance procedures, visual inspections, and very few sensors. But maintenance is very expensive, visual inspections can miss critical problems, and conventional sensors can fail in harsh environments. Can fiber-optic sensing (FOS) address these issues? This is not a new question, but there are some new answers. This paper highlights several structures where FOS is used, and describes the associated successes and challenges for each application. Many successes are coupled to improved FOS tools: better sensor packages, simpler and less expensive instrumentation, improved installation techniques, and more efficient data analysis tools. Examples of each are provided. Particular attention is given to the economics of instrumenting civil structures - when and how it pays. Conclusions include recommendations for future developments that will further accelerate FOS acceptance and use.