Japanese State of the Art on Seismic Retrofit by Fiber Wrapping for Building Structures: Research

The research on seismic retrofit of RC members using continuous fiber sheets is rapidly advancing in Japan. These research activities have been accelerated since the Hanshin-Awajii Earthquake, 1995 becasue this retrofitting technique has an advantage due to lightweight, flexibility, non-welding, and easy handling in construction works. The most preferable retrofitting technique for the existing building being in use is jacketing RC columns with carbon or aramid fiber sheets because of the advantage above. Recently many results of the research on short column with spandral wall, columns with wing wall, beams with slab (T shaped beam), earthquake resisting wall have been reported in Japan. This paper introduces, first of all, these experimental research results in detail and the seismic retrofitting effects by the continuous fiber sheets are comprehensively evaluated. Flexural capacity, shear capacity and the improvement of ductility are discussed to evaluate the effect of reinforcement of continuous fiber sheets. Then, methods for evaluating the seismic retrofit of regular columns with continuous fiber sheets are described. A basic idea of the evaluation method proposed for a regular column is shown, and the problems which should be examined are extracted and explained about these effects. As the summary, the problems which should be solved, research direction and prospect are pointed out for the future research on seismic retrofit by continuous fiber sheets. Research needs for establishment of a design method when various members are reinforced by continuous fiber sheets in the future are also discussed.