Bidirectional substructure pseudo‐dynamic tests and analysis of a full‐scale two‐story buckling‐restrained braced frame

Abstract

SUMMARYA two-story buckling-restrained brace (BRB) frame was tested under bidirectional in-plane and out-of-plane loading to evaluate the BRB stability and gusset plate design. The test comprised pseudo-dynamic loadings using the 1999 Chi-Chi earthquake scaled to the 50%, 10%, and 2% probability of exceedance in 50 years and a cyclic regime of increasing amplitudes of up to 3.0% story drift ratio (SDR). The specimen had a unique configuration where the beams were connected to the columns through shear tabs welded to the column flanges and bolted to the beam webs. Stable hysteretic behavior with only minor cracking at the gussetto-column welds was observed under the pseudo-dynamic tests, with maximum in-plane and out-of-plane SDRs of 2.24% and 1.47% respectively. Stable behavior continued into the cyclic test where fracture of the gusset-to-column welds occurred in the first cycle to simultaneous bidirectional SDR of 3.0%. The observed BRB stability is consistent with a methodology developed for BRB frames under simultaneous inplane and out-of-plane drifts. The specimen behavior was studied using a finite element model. It was shown that gusset plates are subjected to a combination of BRB force and frame action demands, with the latter increasing the gusset-to-beam and gusset-to-column interface demands by an average of 69% and 83% respectively. Consistent with the test results, failure at the gusset-to-column interfaces is computed when frame action demands are included, thus confirming that not considering frame action demands may results in unconservative gusset plate designs.

Hybrid experimental performance of a full‐scale two‐story buckling‐restrained braced RC frame

“…The possible deteriorating out‐of‐plane rotational stiffness of the proposed CAB because of the degradation of the RC members could also affect the BRB end stability at the gusset connection. The seismic performance of the gusset connections in a full‐scale two‐story steel BRBF considering bi‐directional earthquake ground motions has been investigated using substructure hybrid test procedures . In that study, BRB stabilities were re‐evaluated using the method proposed by Takeuchi et al .…”

Numerical Study on the Seismic Performance of a Steel–Concrete Hybrid Supporting Structure in Thermal Power Plants

“…As we know, the pseudo-dynamic test (PDT) method is an effective way to investigate the seismic resistant capacity of building structures subjected to earthquake waves, and it involves online computers that are net worked with each other to control the input forces [12,13]. With the PDT techniques, we can not only simulate the responses of large-scale structures subjected to earthquake, but also observe closely the seismic-resistant capacity of structures using slow loading procedures [14,15]. In view of this, a series of pseudo-dynamic tests were performed on a 1/8 scaled sub-structure, and the general experimental results have been introduced [16].…”

11.37: Hybrid tests of a full‐scale two‐story buckling‐restrained braced RC frame

“…The corner gussets are subjected to secondary frame action loading, owing to the beam-to-column connection opening and closing as the frame deforms. Based on studies of reinforcing ribs in welded moment connections [11], the equivalent strut model was adopted by researchers to investigate the frame action demands on gusset plates [7,12]. Recently, researchers further proposed force demands for single and coupled corner gusset interfaces induced from the frame action effect for steel constructions [7].…”