Summary
This paper presents a ten‐element hybrid (experimental‐numerical) simulation platform, referred to as UT10, which was developed for running hybrid simulations of braced frames with up to ten large‐capacity physical brace specimens. This paper presents the details of the development of different components of UT10 and an adjustable yielding brace (AYB) specimen, which was designed to perform hybrid simulations with UT10. As the first application of UT10, a five‐story buckling‐restrained braced frame and a special concentrically braced frame (BRBF and SCBF) were designed and tested with AYB specimens and buckling specimens representing the braces. Cyclic tests of the AYB, one‐ and three‐element hybrid simulations of the BRBF, and four‐element hybrid simulations of the SCBF inside the UT10 confirmed the functionality of UT10 for running hybrid simulations on multiple specimens. The tests also indicated that AYB was capable of producing a stable hysteretic response with characteristics similar to BRBs. Comparison of the results of the hybrid simulations of the BRBF and SCBF with their fully numerical models showed that the modeling inaccuracies of the yielding braces could potentially affect the global response of the multi‐story braced frames further emphasizing the need for experimental calibration or hybrid simulation for achieving more accurate response predictions. UT10 provides a simple and reconfigurable platform that can be used to achieve a realistic understanding of the seismic response of multi‐story frames with yielding braces, distinguish their modeling limitations, and improve different modeling techniques available for their seismic response prediction.
Nonlinear time history analysis relies on accurate modeling of the critical structural components and their complex interaction with the structure. Previous research indicates that calibration of numerical models can be affected by several factors, including the loading protocols. It is, therefore, critical to study previously developed and calibrated numerical models under more realistic loading histories, and determine whether the calibration process, loading protocols, and the numerical model themselves are adequate for achieving the desired level of accuracy. High fidelity benchmark system-level experimental-based simulation results could allow for a more holistic assessment of such questions.The University of Toronto Ten Element Hybrid Simulation Platform (UT10) was developed to produce such benchmark test results using hybrid simulations with multiple experimental elements subjected to realistic earthquake loads. This paper presents the first such experiment in the UT10 with multi-element and single-element experimental hybrid simulations on a five-story steel structure with buckling-restrained braces, representative of systems with a stable yielding hysteretic response. An adjustable yielding brace system was developed to capture the response of buckling-restrained braces' yielding core. The implications of modeling choices, such as using commonly available models in BRBFs, are studied. The experimental results are then presented and compared with numerical results. The limitations of existing models are identified. Such experimental results can be used by subsequent studies to improve the calibration of numerical models and allow for the development of more robust models, while also justifying the need for new loading protocols that could be used in the calibration process.
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