'Smart repair' strategies using advanced metrology for enhanced structural health monitoring

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Much of our current infrastructure, built of modern materials such as concrete, has or will require extensive repair, in service - often after even a relatively short period of its design life or to extend that life and reduce the costs on 'new build'. Currently an estimated ~600M is spent annually on the repair and maintenance of concrete infrastructure in the UK alone, a figure that is multiplied many times across the developed nations. Serviceability and enhanced whole life performance are critical to effective use and the long-term monitoring of such structures is invaluable to ensure full structural capability, to minimize risk to the public and give value for money. Further, there is a clear future for concrete infrastructure: the advancement of lightweight materials with a long service life is seen as essential to sustainable development, for example using highly durable lightweight, low energy concrete which can be used in a novel and pre-cast products and incorporating within it advanced monitoring systems. However, critical to achieving the maximum value from our infrastructure is a fuller understanding of the needs and challenges of allowing for better assessment of existing structures during their service lifetime as well as the creation of better structures for the future, using new materials. In both cases effective monitoring systems, installed or retrofitted and used to give reliable and informative data, having the confidence of the user community and industry, need to be developed and used widely. Thus monitoring and evaluation of the efficacy of repair strategies, as a key aspect of structural health monitoring, is the target of this proposal. This is made possible, uniquely in this project, by two factors coming together - the availability of a bridge where the damage conditions that have been applied since the bridge was moved to its present site will be well known and closely documented (as part of work done by NPL), as are the repair strategies that have been and will be applied to it. Addressing this in this project is the use of new, calibrated monitoring devices applied both during the repair procedure itself and subsequently, in both cases to allow the effects of the repair on the bridge to be monitored quantitatively and the work is thus very complementary to and adds value to research currently at NPL. Conventional SHM provides an assessment which allows the owners of large engineering assets to schedule maintenance more accurately, and can give an early warning of possible structural failure. The sort of system proposed in this project will provide early warning of potential problems and help in the better planning of maintenance and repair: the proposal herein will allow the repair strategies to be determined, monitored and evaluated. The overall aim is thus for better information to predict the likely potential for failure, the need for repair, the efficacy of the repair and thus the likely lifetime of a structure such as a bridge. This recognizes the wide industrial need for predictive systems that can monitor structures and inform the asset holder on its state of health, both in terms of its physical structure and chemical changes, where the type of structure could include bridges, buildings, power plant, aircraft, chemical plant etc. Even just considering the situation with bridges, a simple clear indication of the structure's health will provide substantial economic benefits since there are over 10,000 bridges worth more than 1M each in the UK alone - offering effective repair and thus cheaper maintenance and lower running costs would thus be of significant benefit.