Tetsuo Yamakawa

Emergency Retrofit for Damaged RC Columns by Fiber Belts Prestressing and Plywoods

After a strong earthquake attacks to a building, damaged structural members such as columns should have sufficient vertical resistance to sustain gravity loads to rescue residents or move equipments. The rehabilitation of a damaged building is called “Emergency Seismic Retrofit” hereafter. Previous experimental investigations have demonstrated by utilizing high-strength steel bar prestressing or aramid fiber belt prestressing, seismic performances of shear-damaged RC columns significantly improved. In following the previous investigations on emergency seismic retrofit of shear-damaged RC columns, in this study a new approach is proposed regarding economic consideration and easy operation. In this method the polypropylene belts are used instead of aramid fiber belts, plywoods instead of steel plates, and customarily-fabricated ratchet buckles instead of specially-fabricated couplers. Experimental results exhibited efficiency of the pro-posed approach for emergency seismic retrofit of shear-damaged RC columns.

Experimental Investigation on Soft-Story RC Frames Retrofitted by Hybrid Wall Technique

In this paper, a new retrofit method, which is called “Hybrid Wall Technique”, is proposed for retrofitting soft-story RC frames. In the proposed technique, steel plates encase the boundary RC columns, and connect to additional steel plates at the bay of the frame with the help of high-strength bolts. After installation of steel plates and high-strength bolts, which are also used as formworks, the additional concrete is cast. Structural performance of the proposed method is verified by experimental investigations conducted on one-bay one-story RC frames. One non-retrofitted frame and three frames retrofitted by thick or thin hybrid walls were evaluated experimentally.