Earthquake simulator testing of a three-story steel building for evaluating built-up box column performance and effect of sliding slab

Abstract

The width-thickness requirement for highly ductile built-up box columns in AISC 341-22 is conservative when comparing the hysteretic responses of highly ductile box columns and I-shaped columns. This study aimed to assess the seismic performance of moderately ductile box columns in a 3-story steel dual frame with a buckling-restrained braced frame (BRBF) and a special moment frame (SMF). The frame specimen was configured in phase 1 testing to allow the slabs to slide relative to the steel frame; Teflon pads were provided between the slabs and steel beams, and horizontal buckling-restrained braces (BRBs) were installed between the slabs and steel beams. In phase 2, the horizontal BRBs were replaced by rigid links such that the frame specimen simulated a conventional construction. Two phases with 17 shake table tests were conducted on the frame specimen. A near-fault motion record, obtained from the 2022 Chihshang earthquake, was used as an input motion. In phase 1, test results showed that the slab sliding system was effective in reducing the floor acceleration by 25% when compared to the rigid slab frame system. In phase 2, the base of moderately ductile built-up box columns still performed well without local buckling even when the interstory drift angle reached 0.045 rad. Postearthquake tests were conducted on the all-steel, first-story BRB that was removed from the building specimen after all shake table tests. A higher-mode buckling of the core plate was observed at both ends of the core, causing a minor strength increase at the end of the test.