Multi-element pseudo-dynamic hybrid simulation of concentric braced frames

The hybrid simulation capabilities of the University of Toronto’s Structural Testing Facilities has undergone significant advancements within the last few years. These advancements include the development of the University of Toronto’s 10-Element Hybrid Simulator, known as the UT10 Hybrid Simulator, for performing multi-element pseudo-dynamic hybrid simulations and also the University of Toronto Simulation (UT-SIM) framework for conducting multi-platform numerical and experimental-numerical simulations. This paper starts with a brief review of the main components and features of the UT10 Hybrid Simulator and is then continued with details of an on-going experimental program, at the University of Toronto, using the UT10 Hybrid Simulator. The experimental program is aimed at seismic performance assessment of a prototype 5-storey steel structure equipped with three alternative types of high-performance concentric braced frames: (1) Buckling Restrained Braced Frame (BRBF), (2) Special Concentric Braced Frame (SCBF), and (3) braced frame with Cast Steel Yielding Brace Systems (YBS). In the hybrid simulations on the BRBF, 1-element and 3-element tests are performed where the BRBs are physically represented by one and three Adjustable Yielding Braces (AYB). Comparison of the experimental results with fully numerical calibrated models confirm that BRB hysteretic response details and the quantity of the physical substructures can significantly impact the accuracy of the BRBF seismic response evaluation. For the hybrid simulations on SCBF, 4-element tests are planned with a special scaled specimen which physically represents the full-scale braces. The nonlinear FE simulation results confirms the similarity of the tensile and pre- and post-buckling compressive response of the scaled specimen and the full-scale braces. Large-scale 4-element hybrid tests are also planned on a 5-storey steel frame with YBS. The outcomes of the above experimental programs can be used for critical review and potential improvements of the currently used modelling techniques and performance based design guidelines for multi-storey high performance braced frames. The experimental programs are part of a study on the effects of the behaviour of the hysteretic energy dissipating braces and the accuracy of their numerical models on the seismic performance and risk assessment of structures.