FRP strengthening of concrete structures: new inventions and applications

摘要

The advantages of FRP strengthening have been shown time and again during the last decade. All over the world several thousand structures retrofitted with FRPs exist. There are various reasons why the retrofit is needed, but since buildings and civil structures usually have a very long life, it is not uncommon that the demands on the structure change with time. The structures may have to carry larger loads at a later date or fulfil new standards. In extreme cases, a structure may need repair, owing to an accident, or to errors made during the design or construction phase, such that the structure needs to be strengthened before it can be used. Over the past decade, the issue of deteriorating infrastructure has become a topic of critical importance in Europe, and to an equal extent in North America and Japan. The deterioration of bridge decks, superstructure elements and columns can be traced to reasons ranging from ageing and environmentally induced degradation, to poor initial construction and lack of maintenance. Added to the problems of deterioration are issues related to the need for higher load ratings and increased numbers of lanes to accommodate the ever-increasing traffic flow on major arteries. As a result, a significant portion of our infrastructure is currently either structurally or functionally deficient. Beyond the costs and visible consequences associated with continuous retrofit and repair of such structural components are the real consequences related to losses in production and overall economic issues related to time and resources caused by delays and detours. As we move into the twenty-first century, the renewal of our lifelines becomes critical. Here, FRP strengthening may be a tool in the overall toolbox to be used to overcome some of the problems related to repair and strengthening of structures. In this paper a short historical background to plate bonding is presented. The paper focuses on the possibility of improving the existing technology and how drawbacks can be overcome.