Executive Summary : | Over the past decades, real-time hybrid simulation (RTHS) has emerged to be an accurate, efficient, affordable and state-of-the-art method for the laboratory simulation of seismic effects in structures. An RTHS combines large-scale physical models with numerical models; thereby, it enables the definition of the 'system' to be expanded beyond the size of typical laboratory physical models and integrates the benefits of physical testing and computational simulations. It enables physical testing of rate-dependent devices because the test is performed in real time. It is used in many foreign laboratories to assess seismic performance of structures. To the PI's knowledge, an RTHS facility is not available in India. Further, its application to simulate structural responses to other hazards (e.g., wind loads) is little researched.
The overarching goal of this proposal is to address the above limitations by implementing, validating and applying the RTHS method to simulate structural responses to seismic and wind loads at the recently completed Pseudo-Dynamic Testing Facility (PDTF) at IIT Kanpur, a large-scale structural testing facility of its kind in the country. The PDTF has recently acquired state-of-the-art equipment through a DST-FIST grant, which favourably paves the way for the current proposal.
The RTHS implementation will use explicit, unconditionally stable and parametrically dissipative direct integration algorithms, developed and used previously by the PI, to enable an accurate and efficient time stepping for systems with many degrees of freedom. A MATLAB and Simulink based software, developed earlier by the PI and colleagues, will be used for efficient computations required for large-scale numerical models. An advanced actuator control algorithm, extensively used by the PI in his previous RTHS studies at Lehigh University, will be used for accurate control of servo-hydraulic actuators. The implemented RTHS method will be validated using numerical simulations and shake table tests of a steel frame building outfitted with a novel damping device, to be developed in the project.
To demonstrate the application of RTHS and to pave the way for future research on passive energy dissipation systems, the project will develop a novel shape memory alloy (SMA) based damping device. It will use a slider mechanism, in which friction at the sliding interface and SMA rods will provide the resistance to sliding. The design will be such that the SMA rods are always loaded in tension. These rods will provide re-centring and partial energy dissipation capabilities to the device, and friction will supplement the latter. The novelty of this device includes its simple design, efficient use of SMA material, flag-shaped large hysteresis, and scalability. Low-rise and tall prototype buildings will be considered for assessment of the device performance under seismic and wind loads through a series of numerical simulations and RTHS considering various hazard levels. |