This study investigates the seismic response of structures with sustainable, long-stroke response modification devices. The main thrust of the dissertation is the investigation of the seismic response of yielding structures equipped with supplemental rotational inertia, or inerters. The last chapter of this dissertation investigates the seismic response of multistory yielding steel structures equipped with pressurized sand dampers.
Inerters are mechanical devices with resisting force proportional to the relative acceleration of their end nodes. This class of response modification devices complements the traditional fluid viscous damping devices with resisting force proportional to the relative velocity at their end-nodes. Mass-amplification is the main benefit of inerter-based devices, which provide a high level of vibration control with a small amount of actual mass.
This study first reviews the seismic response of elastic structures equipped with supplemental rotational inertia. The generalized equations of motion of structures equipped with inerters in any arbitrary story derived. The best seismic performance, obtained when inerter-devices are installed in the bottom story. A time-domain formulation for the response analysis of a single-degee-of-freedom structure and a two-degree-of-freedom 2DOF structure equipped with inerters are developed. The seismic performance of supplemental rotational inertia system compared to traditional energy dissipation mechanism. Both a single inerter and a pair of clutching inerters that can only resist the motion of the structure are examined.
The nonlinear behavior of structures equipped with supplemental rotational inertia is investigated by using the Bouc-Wen hysteretic model. The effect of rigid and compliant inerters supports are examined. The post-yielding behavior of the system is investigated, and the advantages and challenges associated with using supplemental rotational inertia are discussed.
The seismic performance of high-rise yielding structures equipped with the novel response-modification strategy, the outrigger-inerter system, is studied. The proposed seismic control mechanism uses inerters vertically within a conventional core-to-external column outrigger system. To study the seismic behavior of the outrigger-inerter system, a new material developed in C++. This new material is used to represent the behavior of inerters in the OpenSees platform. Both single inerter and a pair of clutching inerters are examined.
This research concludes that supplemental rotational inertia effectively controls the seismic response of structures and could emerge as an attractive response modification strategy with the potential to replace the traditional energy dissipation systems in building structures. The last chapter of this dissertation studies the seismic response analysis of the 9-story SAC building equipped with pressurized sand dampers. Sand dampers are low-cost energy dissipation devices wherein the material enclosed within the damper housing is pressurized sand. The strength of the pressurized sand damper is proportional to the externally exerted pressure on the sand via prestressed steel rods. The strong pinching behavior of the pressurized sand dampers is characterized by a previously developed 3-parameter Bouc-Wen hysteretic model. The model was implemented in the open-source code OpenSees with a C++ algorithm and used to analyze the seismic response of a 9-story SAC steel building subjected to several strong ground motions.
Civil Engineering and Environmental Engineering
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Moghimi, Gholamreza, "Response Modification and Seismic Protection of Yielding Structures Equipped with Inerters and Hysteretic Dampers" (2021). Civil and Environmental Engineering Theses and Dissertations. 15.