Hybrid simulation methods have been developed to simulate the nonlinear response of a structure subjected to earthquake load. In recent years, there has been efforts to apply the hybrid simulation method for structures subjected to fire load as well as wind load. The main advantage of the hybrid simulation method is that the component(s) that is(are) difficult to be represented with (a) numerical model(s) can be directly modelled with a physical specimen in a testing facility while the rest of the structural system is modelled numerically. As an example, unsteady aeroelastic (aerodynamic) force and nonlinear structural behaviour of the systems are the components need to be tested for wind- and earthquake- hybrid simulations, respectively. The hybrid simulation method is beneficial when there is two-way interaction between the physical model and the rest of the structural system.
Wind tunnel testing has been used in design of tall buildings and long-span bridges. Wind tunnel testing has been considered to be the most reliable method to measure wind loads on structures, whereas other methods such as Computational Fluid Dynamics (CFD) are inaccurate in some details and require considerable computing time.
Wind tunnel tests, however, also have some challenges. In the aeroelastic tests of buildings and bridges, the mass, stiffness, and damping property of a model need to be calibrated to satisfy the dynamic similitude law, which requires considerable engineering hours. The interaction between the wind and the motion of a building or a bridge deck is highly amplitude-dependent. However, due to limited resources in typical wind tunnel tests, the measurements are usually made for a nominal-amplitude motion based on the linearity assumption between the amplitude of motion and the aerodynamic force. Such amplitude-dependency can only be measured by expensive aeroelastic tests in current wind engineering practice.
In this paper, we present the design of two experimental apparatus with which a building model or a bridge deck can be tested in a wind tunnel testing facility of Gradient Wind Engineering. In the building test apparatus, two linear motors are used to control two modes of responses in along-wind and across-wind directions. For bridge section test apparatus, two sets of two linear motors are configured to control vertical and torsional responses. The experimental apparatus will be assembled in summer 2018, and dynamic characterization of the system will follow. Real-time hybrid simulation method will be validated with an external forced excitation at the Structural Testing Facility of the University of Toronto, which will be followed by wind tunnel tests at Gradient Wind Engineering in Ottawa.