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

本课题的研究成果包括两部分：一是利用高弹性模量碳纤维片材提高带结构墙的钢筋混凝土框架抗剪性能；二是开发碳纤维与芳纶纤维或玻璃纤维混合纤维片材。对于第一部分，由于柱的长度变长，变形能力大，抗剪能力低，因此，对于与腰高墙体相邻的R/C柱，以前通过在柱与墙体之间设置开缝来提高抗剪能力。本文提出了一种新的加固方法，通过对齐腰高墙体的角部与立柱进行加固，既能获得较大的延性，又能获得较高的抗剪能力。这种加固的重点是用l型钢覆盖并用螺栓挤压的墙壁角，以及将覆盖柱子底部的纤维片的尖端固定在钢上。对带开口剪力墙框架结构的进一步改进是利用带开口剪力墙框架结构的刚度比无开口剪力墙框架结构的刚度低，而不是增加抗剪强度。我们提出了一种新的方法，即通过将纤维板连接在l型钢的背面，并将其固定在墙角上，从而加固开孔旁的柱和墙。在第二部分，我们开发了一种新的混合玻璃钢片材，它是由高弹性模量的碳纤维片材和另一种材料片材，如芳纶或玻璃纤维，弹性模量低，但伸长率相对较大。当碳纤维与另一种纤维的复合比在一定范围内时，由于混杂效应，复合薄板具有与钢相似的准屈服气氛的应力应变关系曲线。因此，复合薄板可用于提高R/C梁的抗弯强度和变形能力。少

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