Development of techniques to improve structural performances of reinforced concrete buildings by new FRP materials

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The results of this research project is consisted of two parts: improvement of shear resistance of reinforced concrete frames with structural walls by using carbon fiber sheets with high elastic modulus, and development of hybrid fiber sheets composed of carbon fiber and one another fiber of aramid or glass fiber.As for the first part, the shear resistance for R/C columns adjoining waist-high walls has been improved previously by setting slits between the column and walls because the length of columns became so longer that it had large deformability but low shear resistance. However we proposed the new improvement method that could obtain not only large ductility but also high shear resistance by strengthening the corner of the waist-high walls together with columns. The points of this strengthening are on confining the corner of walls covered by L-shaped steels and squeezed by bolts, and on anchoring the tips of fiber sheets covered the bottom of the columns to the steel.The point of … More improvement for shear wall - frame structures with an opening in the wall is to put large toughness instead of increasing shear strength, using the low stiffness of the shear wall frame structures with an opening comparing to the structures with no opening. We proposed the new method such as strengthening columns and walls beside an Opening by fiber sheets which were jointed on the back side of L-shaped steels bolted to the corner of the walls.As for the second part, we developed the new hybrid FRP sheet which was consisted of carbon fiber sheet showing high elastic modulus and another material sheet such as aramid or glass fiber showing low elastic modulus but relatively large elongation. This hybrid sheet has a stress strain relation curve with quasi-yielding atmosphere similar to that of steel by hybrid effect, when the composite ratio of carbon fiber to the other fiber is used within an adequate range. Therefore the hybrid sheet can be applied to improvement flexural strength and deformability of R/C beams. Less