SHAKING TABLE TEST OF REINFORCED CONCRETE FRAMES FORVERIFICATION OF SEISMIC STRENGTHENING WITH POLYESTERSHEET

摘要

A new method of strengthening reinforced concrete columns, named as SRF, has been developed andverified through a series of static column tests. Through these test series, the method has been improved tobe effective to prevent the loss of capacity not only against axial load but also against lateral loadreversals. In addition, a dynamic test was planned and conducted for the verification of the effectivenessof the new strengthening method, especially on the ultimate structural safety. The specimens are two onethirdscale reinforced concrete wall-frame structures with considerable stiffness and strength eccentricityin the first story. The two specimens with the same sectional dimensions and reinforcement details wereconstructed and tested simultaneously on the large shaking table at NIED, Tsukuba. One was a barereinforced concrete structure designed following old practice on reinforcement details in Japan, while theother was strengthened before the test with polyester fiber sheet, called as SRF. The torsional response inthe first story magnified the displacement of the independent columns on the weak side row due to thelarge eccentricity, and these two columns without strengthening failed in shear resulting in collapseassociated with loss of the axial load carrying capacity, whose collapse process was traced on the basis oftest results. On the other hand, the frame strengthened by SRF not only responded stably to the same inputmotion with minor damage but also survived still higher levels of succeeding input motions. The cost ofretrofit by SRF would remarkably be reduced from that by existing technology.