Pseudo Dynamic Tests and Analysis of A Full Scale Two-story Steel Buckling Restrained Braced Substructure under Bi-directional Earthquake Loads
Date Issued
2005
Date
2005
Author(s)
Tsai, Cheng-Yu
DOI
zh-TW
Abstract
In recent years, several researchers have confirmed that buckling restrained brace (BRB) is a very effective energy dissipation element to reduce seismic responses of building structures. It has been shown in many research laboratories that BRB components can sustain large cyclic inelastic strain reversals and stably absorb a significant amount of energy without failure. Thus, buckling restrained braced frame (BRBF) has gained wide acceptance in Japan, Taiwan and North America. While most of the BRB tests have confirmed the excellent performance of the BRB component in absorbing energy, recent pseudo dynamic tests conducted in October 2003 in the National Center for Research on Earthquake Engineering (NCREE) on a full scale three-story BRBF has revealed the importance of the gusset plate details. Gusset plates designed according to the conventional methods may not require any gusset edge stiffener, but could be buckled under large BRB compressive forces. In order to further investigate the gusset plate design methodology, a full scale two-story BRBF is tested in NCREE in this study using substructure pseudo dynamic test procedures and considering bi-directional earthquake load effects of three different seismic hazard levels.
The objectives of this study include: 1) investigate the current and modified design criteria of the BRB gusset plate subjected to axial load and out-of-plane bending, 2) conduct the ABAQUS finite element analysis to investigate the buckling strength of the gusset plate details adopted in the 2-story BRBF specimen, 3) incorporate the Platform for Inelastic Structural Analysis for 3D System (PISA3D) into the servo-control loop for substructure hybrid tests, 4) provide seismic design recommendations for the BRB gusset plate subjected to bi-directional force and deformations.
Test results showed that the 2-story BRBF specimen can be very effectively tested by using the substructure pseudo dynamic test procedures, particularly with real-time webcasting of test results. The 2-story BRBF specimen sustained three sets of ground accelerations (scaled to represent less than 50%, 10% and 2% chance of exceedance in 50 years) without any sign of strength of stiffness degradation. It is found from the tests that the out-of-plane deformational demand imposed on the gusset plates can be satisfactorily estimated by linear interpolation of the inter-story drift considering the dimension of the gusset plate with respect to the story height. It is confirmed from the test and ABAQUS analysis results that after adding the gusset plate edge stiffeners, an effective length factor of K=1.0 can be incorporated into the Whitmore and Thornton methods for the design of gusset plates.
Subjects
挫屈束制支撐
構架
擬動態試驗
Buckling Restrained Brace
Pseudo Dynamic Tests
Type
thesis
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