Natural Hazards Research Summit 2022: 3D Real-Time Hybrid Simulation Studies of a Tall Building with Novel Tuned Mass Friction Dampers for Wind Hazard Mitigation

A new semi-active friction device using band brake technology, termed the Banded Rotary Friction Damper (BRFD),
has been fabricated at the NHERI Lehigh experimental facility. The device is a second-generation BRFD where its
semi-active mechanism is achieved using two electric actuators. The BRFD generates a variable damping force as
a linear function of the input force provided by the electric actuators, where the force amplification ratio (FAR) is
equal to about 70. The FAR is defined as the ratio of BRFD damping force output-to-electric actuator force input.
The presentation will present the results of a study using real-time hybrid simulation (RTHS) to investigate the
performance of the BRFD’s in mitigating wind vibrations on a forty-story building. The building consists of steel
braced frames that are augmented by outrigger systems about the minor axis of the floor plan. Nonlinear viscous
dampers are placed in the outriggers to control floor accelerations about the minor axis of the building. In the
orthogonal direction only braced frames exist, consequently, the structure’s response is susceptible to increased
floor accelerations and inter-story drift. A Tuned Mass Friction Damper (TMFD) is therefore placed at the roof and
positioned in order to suppress the building’s response in the orthogonal direction to the outrigger system. First, the
details of the prototype of the BRFD are presented. Second, details relating to the TMFD consisting of a moving
mass, a stiffness element, and the BRFD are introduced. Lastly, details of the RTHS study and the results are
presented. The building, the moving mass, and the stiffness element in the TMFD are part of the analytical
substructure while the BRFD and large-scale nonlinear viscous dampers form multiple experimental substructures
for the RTHS. The creation of the analytical model involved discretely modeling each of the members of the building
using nonlinear elements, with the combined analytical and experimental substructures representing about 2000
degrees of freedom. The explicit, unconditionally stable dissipative Modified KR-Alpha integration algorithm is used
to accurately integrate the equations of motion. Real-time online model updating is used to update parameters of
some of the nonlinear viscous dampers that are modeled via the analytical substructure. The building’s
accelerations and inter-story drift from RTHS from controlled and uncontrolled cases are compared, where these
cases correspond to the structure with and without the TMFD, respectively. Results show that the TMFD produces
significant wind vibration reduction on both maximum lateral floor accelerations and inter-story drift.