EXPERIMENTAL RESEARCH ON SEISMIC PERFORMANCE OF BUCKLING RESTRAINED REPLACEABLE CHORD IN OUTRIGGER

To improve the ductility and post-earthquake repair capacity of the chord in outriggers, a buckling restrained replaceable chord was proposed. To validate the feasibility and reliability of this new chord, three types of 1/3 scaled chords, including one conventional chord with reduced beam section (RBS) and two new buckling restrained replaceable chords with different construction details, were tested through pseudo-static experiments. The corresponding deformation, strength, stiffness and energy dissipation capacities were compared and analyzed. The results indicate that conventional chord exhibits a severe degradation of strength and stiffness after buckling under the axial compressive load. As for the proposed chords, the damage is successfully controlled and concentrates in the external RBS plates, and the buckling of RBS plates is effectively prevented by the buckling restrained plates, thus avoiding the buckling of flanges in the chord. The average ductility coefficient reaches twice of that of conventional chord, which satisfies the ductility demand under the compression-bending-shear interaction. The research outcome can provide a reference for the development of high-performance outrigger.