Interaction of Two Adjacent Structures Coupled by Inerter-based System considering Soil Conditions

The inerter-based systems have proven to be effective for vibration control of adjacent structures. The interaction through the soil medium between adjacent structures in urban areas is generally accepted. However, existing studies concerning the inerter-based adjacent structures are primarily based on the assumption of a fixed base, without considering the inevitable interaction. To address this issue, this study incorporated the soil effects into the theoretical analysis of adjacent structures interconnected by an inerter system, and correspondingly develops an optimal design framework for such system. Employing a classic discrete model for structures and soil, the interaction behavior between inerter-based adjacent structures and soil was extensively studied in a comparative analysis. Based on the revealed interaction phenomena, the need for considering the soil condition in the design of an inerter system for adjacent structures was addressed, and a performance-demand-based optimal design framework was developed. The results indicated that for inerter-based adjacent structures spaced closely, the coupled interaction effect of soil and structure requires careful consideration, especially in soft soil conditions. Owing to the soil effects, the inerter system exhibited a weakened effectiveness for displacement reduction. A larger inner deformation of the inerter system is required to meet the demand for energy dissipation. With consideration of the soil condition, the proposed design method can satisfy the pre-specified target displacement demands for adjacent structures, simultaneously optimizing the control cost as an economical solution

Performance analysis of cables with attached tuned-inerter-dampers

Cables are structural elements designed to bear tensile forces and experience vibration problems due to their slenderness and low mass. In the field of civil engineering, they are mostly used in bridges where the vibrations are mainly induced by wind, rain, traffic and earthquakes. This paper proposes the use of a tuned-inerter-damper (TID) system, mounted on cables to suppress unwanted vibrations. These are to be attached transversally to the cable, in the vicinity of the support, connected between the deck and the cable. The potential advantage of using a TID system consists in the high apparent mass that can be produced by the inerter. Our analysis showed that the modal damping ratio obtained is much higher than in the case of traditional dampers or tuned mass dampers, leading to an improved overall response. An optimal tuning methodology is also discussed. Numerical results are shown with a cable subjected to both free and forced vibrations and the TID performance is improved when compared with equivalent dampers

Shake table testing of a tuned mass damper inerter (Tmdi)-equipped structure and nonlinear dynamic modeling under harmonic excitations

This paper presents preliminary experimental results from a novel shaking table testing campaign investigating the dynamic response of a two-degree-of-freedom (2DOF) physical specimen with a grounded inerter under harmonic base excitation and contributes a nonlinear dynamic model capturing the behavior of the test specimen. The latter consists of a primary mass connected to the ground through a high damping rubber isolator (HDRI) and a secondary mass connected to the primary mass through a second HDRI. Further, a flywheel-based rack-and-pinion inerter prototype device is used to connect the secondary mass to the ground. The resulting specimen resembles the tuned mass damper inerter (TMDI) configuration with grounded inerter analytically defined and numerically assessed by the authors in a number of previous publications. Physical specimens with three different inerter coefficients are tested on the shake table under sine-sweep excitation with three different amplitudes. Experimental frequency response functions (FRFs) are derived manifesting a softening nonlinear behavior of the specimens and enhanced vibration suppression with increased inerter coefficient. Further, a 2DOF parametric nonlinear model of the specimen is established accounting for non-ideal inerter device behavior and its potential to characterize experimental response time-histories, FRFs, and force-displacement relationships of the HDRIs and of the inerter is verified

Inelastic torsional buckling of simple three-dimensional moment resisting frame

Recent massive earthquakes have raised concerns that megathrust earthquakes with magnitude 9 can occur in the near future. This article discusses the critical behavior of structures involving torsion caused by extreme ground motions. Unlike factors such as mass and stiffness eccentricity and accidental torsion in a structure that induce torsion, torsional buckling can occur in a moment-resisting frame (MRF) when all beam ends in the longitudinal and transverse directions yield in the lower stories, even if the frame is well designed and its eccentricity is negligibly small. In this study, the theoretically predicted buckling load was presented and validated via numerical analyses. This article shows that excluding the P-Delta effect resulted not only in underestimated deformation but also in overlooked torsional buckling. This study suggests that a high-rise MRF designed in accordance with modern seismic design codes can suffer torsional collapse when the beam ends of the lower stories yield owing to extreme ground motion. Based on these findings, we recommend considering the P-Delta effect when examining the critical behavior of high-rise buildings so as not to overlook the brittle failure mode

EACS 2016 paper - EFFICACY OF TUNED VISCOUS MASS DAMPER SEISMIC CONTROL SYSTEM INCORPORATED INTO A HIGH-CEILINGED STOREY

<div>EACS 2016 Paper No. 173</div><div><br></div>In Japan, the application of energy-dissipating devices in high-rise buildings has increased significantly since the 1990s. Many recently constructed high-rise buildings containing energy dissipaters enclose large spaces with high ceilings, such as concert halls and theaters, where there is concern that the efficacy of the energy dissipaters incorporated into such high-ceiling frames might be compromised because of long and thereby flexible supporting members. A viable way to somewhat exploit the flexibility of a damper-supporting member in a high-ceilinged frame is to employ a tuned viscous mass damper (TVMD), which consists of an apparent mass produced by rotary inertia and a viscous element, as well as a flexible spring, resulting in an energy-dissipating system similar to a conventional tuned mass damper (TMD). When the supplemental vibration system consisting of the apparent mass and the flexible supporting spring is properly tuned to the primary structure, the deformation of the viscous element is amplified, whereas the deformation of the supporting member results in decreased deformation of the damping element and thus to decreased energy dissipation in conventional devices. An analytical example illustrates the efficacy of a TVMD incorporated into a high-ceilinged frame