SEISMIC BRACE USING ARAMID FIBER ROPE TO REINFORCE BUILDING

The aramid fiber has excellent properties such as tension strength, heat and chemical resistance, dimensional stability and durability. A high performance fiber rope made of twisted aramid fibers is lightweight and has high strength in comparison with general structural members such as steel frames. Moreover, it can be used outdoors and combined with concrete because the aramid fiber is resistant to acid and alkali. We have studied to apply this fiber rope for building structural members. In this paper, a seismic brace using the aramid fiber rope is introduced so that the building can be easily reinforced in a short period of time. The seismic brace consists of the aramid fiber rope and the fitting which connects the rope to the structural member. Since the aramid fiber is hard to be plastically deformed and the repulsive force when compressed is small, enough frictional force cannot be obtained by compression connection. For this reason, a wedge-shaped fitting is used for grasping the rope firmly. First, the wedge shapes, which are taper angle and length of the fitting members, are optimized to reduce stress concentration and ensure the original strength of the fiber rope. Through design studies, appropriate wedge shapes of the connecting fitting is obtained to ensure the original strength. Then, workability is investigated for assembling the fiber rope to the connection fitting at construction stage. For the fiber rope, the fibers are twisted into a bundle and the pluralities of twist bundles are knitted. The fibers are placed around the sleeve hole, and the wedge is driven into this sleeve hole. For the assembling workability, the rope end treatment and fiber density deviation are studied. Through these studies, points to pay attention at the assembling stage become clear. Finally, load-bearing wall tests, where the developed seismic brace is attached to the wood frame, are performed to confirm the effectiveness. Here, test conditions are one-way repeated loads. Through experiments, it is confirmed that the wood frame can be reinforced by the seismic brace using the fiber rope.