EXPERIMENTAL STUDY ON THE SEISMIC PERFORMANCE OF ENERGY DISSIPATION OUTRIGGERS

Based on an actual building project (i.e., a super-tall frame-core-outrigger building located in zone of 8° seismic intensity), the seismic performances of three types of 1:3 scaled outriggers with different construction details are investigated through pseudo-static experiments. The experiments highlight three drawbacks of the regular outrigger, i.e., rapid degradation of bearing capacity, poor ductility and energy dissipation capacity, which are attributed to the overall buckling of web members and flexural yielding induced local buckling of flanges on the chords. Hence, web members are being replaced by buckling restrained braces (BRB) to improve the corresponding energy dissipation capacity. In addition, the reduced beam section (RBS) connection is adopted for the chords to improve the deformation capacity and prevent the flanges of chords from flexural yielding induced local buckling. The test results indicate that low-cycle fatigue damage often occurs at weld connections on the webs of chords, which hinders the fully development of the energy dissipation capacity of BRB. In contrast, the proposed outrigger with a combination of BRBs for the web members and RBS for the chords shows good seismic performance, including good deformation capacity, stable bearing capacity and sound energy dissipation capacity. The outcomes of this work will provide a useful reference for the seismic design of outriggers.