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

Earthq Engng Struct Dyn

et al. 2017

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Summary To improve the efficiency of model fitting, parameter identification techniques have been actively investigated. Recently, the applications of parameter identification migrated from off‐line model fitting to on‐line model updating. The objective of this study is to develop a gradient‐based method for model updating to advance hybrid simulation also called hybrid test. A novel modification of the proposed method, which can reduce the number of design variables to improve the identification efficiency, is illustrated in detail. To investigate the model updating, simulated hybrid tests were conducted with a 5‐story steel frame equipped with buckling‐restrained braces (BRBs) utilized in the shaking table tests conducted in E‐Defense in Japan in 2009. The calibrated analytical model that was verified with the test results can serve as the reference model. In the simulated hybrid tests, the physical BRB substructure is numerically simulated by utilizing a truss element with the 2‐surface model identical to the part of the reference model. Such numerical verification allows simulation of measurement errors for investigation on the performance of the proposed method. Moreover, the feasibility of sharing the identified parameter values, which were obtained from the physical substructure responses, with the relevant numerical models is also verified with the artificial component responses derived from the physical experiments.

Section: Discussionmentioning

confidence: 99%

Section: Overview Of Parameter Identificationmentioning

confidence: 99%

Parameter identification for on‐line model updating in hybrid simulations using a gradient‐based method

Chuang

Hsieh

Earthq Engng Struct Dyn

et al. 2017

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“…To develop a robust and cost‐efficient method to implement BRBs in a new RC construction, seismic design and analysis methods for using a steel cast‐in anchor bracket (CAB) system as the interface for the BRB and RC members have been proposed in the companion study . Experimental results show that a properly designed and constructed BRB‐RCF exhibited satisfactory seismic performance during the hybrid and cyclic loading tests.…”

Section: Two‐story Brb‐rcf Testsmentioning

confidence: 99%

“…Experimental results show that a properly designed and constructed BRB‐RCF exhibited satisfactory seismic performance during the hybrid and cyclic loading tests. Seismic design and analysis methods, fabrication and test procedures, and experimental and analytical results for a full‐scale 2‐story BRB‐RCF specimen as well as design recommendations for the BRB‐RCF system have been documented in detail . In this paper, the key features of the BRB‐RCF test program are briefly described hereafter as they are required in discussing or comparing with the analytical program presented later.…”

Section: Two‐story Brb‐rcf Testsmentioning

confidence: 99%

“…However, the assumption of a rigid steel casing is made for the BRBs in these 2 models. The evident steel casing flexural deformation coupled with the gusset buckling were clearly observed in the aforementioned BRB‐RCF tests . Thus, this paper proposes a method to evaluate the first‐story BRB and gusset buckling that occurred in the aforementioned test.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Seismic performance analysis of BRBs and gussets in a full‐scale 2‐story BRB‐RCF specimen

Earthq Engng Struct Dyn

Chen

et al. 2018

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Summary The implementation of buckling‐restrained braces (BRBs) for new reinforced concrete frame (RCF) constructions is limited. This study investigates the seismic forces and stability in the BRBs and gussets of a 2‐story full‐scale RCF specimen by using Abaqus models and a newly proposed stability evaluation method. The hybrid and cyclic loading test results are accurately predicted by the Abaqus analyses. Existing methods for computing the gusset interface forces for steel buildings from both the brace and the frame actions are compared with the Abaqus results. The applicability of these methods for the BRB‐RCF design is critically evaluated. It is confirmed that the Parallel‐2 method is suitable for estimating the BRB force demand imposed on the corner gusset and the generalized uniform force method is good for the corner gusset at the base. In addition, existing stability evaluation methods for BRBs and gussets are applied to investigate the out‐of‐plane (OOP) buckling of the first‐story BRB observed at the end of tests. The proposed stability model incorporates the BRB restrainer's flexural effects and 4 rotational springs in assessing the BRB's buckling. This model confirms that the BRB and the gusset's OOP buckling limit states could be coupled and must be evaluated together. By incorporating the flexural effects of the steel casing and the infilled grout, the proposed model satisfactorily predicts the OOP buckling of the first‐story BRB and gussets. These research results can be used for the implementation of BRBs in new RC frame constructions.

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

2017

ce papers

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A novel implementation of buckling-restrained braces (BRB) in new reinforced concrete (RC) frame construction is investigated. Seismic design and analysis methods for the use of the proposed steel cast-in anchor bracket (CAB) as the connection for the BRB and RC members are investigated. The steel CAB is designed to resist the normal and shear forces transferred from the BRB in order to secure the seismic performance of RC buildings. In this study, a full-scale two-story RC frame with BRBs (BRB-RCF) is tested using hybrid and cyclic loading test procedures. The BRBs are arranged in a zigzag configuration and designed to resist 70% of the story shear. The gusset design incorporates the BRB axial and RC frame actions, while the beam and column members comply with ACI 318-14 seismic design provisions. When the inter-story drift ratio for both stories reached 3.5%, the overall lateral force versus deformation response was still very stable. The hysteresis energy dissipation ratios in the four hybrid tests range from 60% to 94% in the two stories, indicating that BRBs can effectively dissipate seismic input energy. Test results confirm that BRBs enhanced the RC frame stiffness, strength and ductility, complied with performance-based seismic design. No failure of the proposed steel CABs and RC discontinuity regions was observed in the tests. This study demonstrates that the proposed design and construction methods for the CABs are effective and practical for real applications.