Substructural Pseudo Dynamic Tests of a 2-story Buckling Restrained Braced Frame
Subjected to Bi-directional Earthquake Loads
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ANALYTICAL ASSESSMENT OF A 2-STORY BRBF FOR YUAN-TAO WENG1), JUI-LIANG LIN2), CHENG-YU TSAI3), KEH-CHYUAN TSAI4) 1) National Center for Research on Earthquake Engineering, Taipei, Taiwan |
| ABSTRACT |
| In this paper, the analytical studies of a 2-story buckling-restrained-bracing frame (BRBF) to be tested using sub-structural pseudo-dynamic testing (PDT) procedures are described. The seismic ground acelerations considered in this study was recorded in the 1999 Chi-Chi earthquake. The ground accelerations are scaled up to represent 50%, 10%, and 2% probability of exceedance in 50 years and bi-directionally applied in the transverse and longitudinal directions simultaneously. The displacement-based seismic design procedures used in the design of the BRBF is presented. A systematic approach to determine the earthquake scenario for the test is developed. For the first phase of the test, analytical results suggest that the peak story drift is likely to reach 0.025 radian in the transverse direction under the 2/50 exceeding-probability earthquake. It also shows that the allocation of actuators in the BRBF direction might be adequate. For the second phase of the test, the analytical model is adjusted to form three planar asymmetric structures. These three asymmetric structures are coupled in translational and rotational motions with different extent. One of the objectives of the Phase II test is to validate the η-MPA procedures in estimating the seismic demands of asymmetric structures. The analytical results obtained by η-MPA procedures and response history analysis (RHA) are compared. |
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COMPRESSIVE BEHAVIOR OF BUCKLING-RESTRAINED MIN-LANG LIN1), KEH-CHYUAN TSAI2), PO-CHIEN HSIAO3), CHENG-YU TSAI4) 1) National Center for Research on Earthquake Engineering, Taipei, Taiwan |
| ABSTRACT |
| Buckling-restrained braced frames (BRBF) have gained notable acceptance in Taiwan recently because of its excellent seismic performance and cost-effectiveness. Compare to the traditional concentric braces, buckling-restrained braces (BRBs) have a high compression strength similar to the tension yielding behavior. The gusset connections must be designed to prevent instabilities when transmit high compression forces of the BRBs. In this paper, experimental behavior of a buckled gusset connections in a full-scale 3-story 3-bay CFT/BRB frame specimen tested in the structural laboratory of NCREE is presented, theoretical study and finite element analysis of gusset connections are also described in this paper. In order to investigate the BRBF system subjected to the bi-directional earthquake loads, a full-scale 2-story single-bay BRBF specimen has been constructed for testing in March of 2005. In order to examine the effectiveness of various stiffening schemes for the gusset plate, results of the finite element analysis are presented. It!|s illustrated from the gusset plate buckling analysis that proper stiffeners are effective to increase the buckling strength of the gusset plate. |
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