This paper provides an overview of three different instrumentation schemes used to monitor long term performance of FRP repaired piles in tidal waters. These schemes were evaluated in four demonstration projects extending nearly five years. Two of these used linear polarization to estimate the corrosion rate while the third focused on the variation in the corrosion current. Problems associated with selection, installation and monitoring are described and representative results presented from all three systems. The results suggest data from linear polarization is more consistent. Findings indicate FRP wrapping lowers the prevailing corrosion rate.

Structural health monitoring and sensing are rapidly developing fields of study that have been successfully applied to engineered structures, such as aircraft frames. The implementation in concrete structures, however, is neither common nor currently accepted. ACI Committees 236, Materials Science of Concrete, and 444, Analysis for Concrete Structures, undertook an effort to organize a technical session and special publication that recognize new achievements in this promising field of research. The objective of this effort is to increase awareness of leading research that applies this technology to concrete structures, and thus to promote interest in the field. Many quality papers were submitted in response to the original call for papers for this session; regrettably, several worthy papers could not be included. The subject matter of the selected papers represents a broad range of topics, from the development of specific types of embedded sensors for concrete to the implementation of wireless sensor networks to managing infrastructure systems. This volume will be of interest to engineers, researchers, and students who wish to learn more about this important, dynamic, and developing topic.

Routine management and maintenance of civil infrastructure is undertaken based on structural health indicators from qualitative information gathered during inspections. The need to measure and collect data reflective of the true state of the infrastructure is crucial for proper management of the system. Presented in this paper are methods for incorporating field measurements for improved condition assessment. A full scale field deployment of a wireless, lowcost and automatic system for structural health management and condition assessment of highway structures is shown to demonstrate the ability of obtaining the necessary behavior characteristics. A short-span integral-abutment bridge was instrumented with a developed wireless sensor system measuring strain, in real time through a single network, monitoring the behavior of the structure under various loading conditions. Measurements validated the performance characteristics of the bridge, including transverse moment distribution, end fixity, and composite action of the girders and bridge deck.

Cementitious materials are generally classified as semi-conductors that are capable of carrying electricity when an external electrical signal is applied. The electrical properties of cementitious materials have been widely explored for monitoring their internal hydration processes. However, comparatively less work has been done in using the inherent electrical properties of cementitious materials for structural health monitoring. In this study, the electrical properties of a unique strain-hardening fiber reinforced cementitious composite termed Engineered Cementitious Composite (ECC) are utilized for monitoring the performance and health of ECC structural components. Previous work has utilized two- and four-point probe techniques for measuring ECC bulk conductivity and illustrating the piezoresistive properties of the material. This work introduces electrical impedance tomography (EIT) as a powerful sensing methodology that measures the spatial distribution of conductivity over large areas of ECC elements. With a tomographic mapping of ECC conductivity, the distribution of strain fields and cracks in ECC elements can be observed in incredible visual detail.

There is a need in industry for new devices for the monitoring of chloride ion ingress in structural concrete. This work reports on the development of a reflective, gold-coated long period grating-based senor for the measurement of chloride ions in solution, with potential for evaluating the corrosion condition of concrete structures. The sensor scheme is based around a long period fibre grating (LPG)-based Michelson interferometer where the sensor was calibrated and evaluated in the laboratory using sodium chloride solutions, over a wide range of concentrations, from 0.01 M to 4.00 M. The grating response yields shifts in the spectral characteristic of the interferometer, due to the change of refracting index of the solution surrounding it. It was found that the sensitivity of the device could be enhanced over that obtained from a bare fibre by coating the LPG-based interferometer with gold nanoparticles.