Smart composites for civil infrastructure applications

Fibre reinforced polymer (FRP) composites have become gradually accepted by the civil engineering industry for the repair and rehabilitation of concrete structures in recent years. Extensive research on the use of a host of different forms of FRP forms, such as rods, plates, grids and jackets, has led to confidence in their design for strengthening work. Is it however extremely difficult so assess the structural performance of a strengthened structure using conventional non-destructive evaluation (NDE) technologies such as strain gauges, dye-penetrant, x-ray, radiography and acoustic emission. One form of NDE which has attracted research attention of late is the use of optical fibre sensors as they have the potential of providing real-time structural health monitoring. The sensors, which are typically embedded into the strengthening work, are capable of being used to assess damage and warn of impending weakness in the structural integrity of the structures at any marginal situations. The development of distributed fibre-optic sensors, which provide a large number of continuously distributed parameters such as strain, temperature and vibration profile due to traffic loading, is also of great interest in most engineering applications. In this paper, the use of glass fibre composites and embedded fibre-optic Bragg grating strain sensors as external reinforcement and structural health monitoring devices, respectively, for concrete structures are introduced. The potential applications of FRP reinforcing bars with integrated fibre-optic sensors, for new structures and known as a “Smart Composite”, is another real-time structural health monitoring application discussed in this paper.