• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.246-251
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• 2003

This paper presents an experimental study on the energy dissipation characteristics of viscous damping wall (VDW). VDW is consisted of a plate floating in a thin case made of steel plated filled with highly viscous silicone oil. Because VDW demonstrates both viscous damping and stiffness characteristics, the viscous resisting force can be expressed as the sum of velocity dependant viscous damping force and displacement dependant restoring force. The viscous resisting force and energy absorbing capacity can be easily adjusted by changing three factors, i.e. viscosity of the fluid, gap distance and area of the wall plates. VDW was tested using a series of harmonic (sinusoidal) displacement history having different frequency and amplitude and the force-displacement relationship was recorded. The relationship between dissipated energy with three factors and the influence of exciting frequency on resisting force were Investigated

• Earthquakes and Structures
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• v.7 no.6
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• pp.1171-1186
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• 2014

Damping is one of the parameters that control the performance of structures when they are subjected to seismic, wind, blast or other transient shock and vibration disturbances. By adding supplemental viscous dampers, the energy input from a transient deformation is absorbed, not only by the structure itself, but also by the supplemental dampers. The aim of this study is to evaluate the values of both damping and ductility reduction factors for steel moment resisting frames with supplemental linear viscous dampers. Two-dimensional finite element models have been established for a range of low to mid rise buildings with different parameters: number of floors; number of bays; and number of dampers with different supplemental damping ratios (from 5% to 30%). A parametric study has been performed using time history analyses and a well-documented research method (N2-method). In addition, an equation has been proposed for each reduction factor based on regression analysis for the obtained results. The results of the Time history analyses are compared with those of a modified N2-method. Moreover, a comparison with values specified in the European code EC8 and the Egyptian code ECP-201 has been performed.

• Earthquakes and Structures
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• v.18 no.6
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• pp.667-675
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• 2020

The current study compares the effect of structure-soil-structure interaction (SSSI) on the dynamic responses of adjacent buildings and isolated structures including soil-structure interaction (SSI) with the responses of fixed-base structures. Structural responses such as the relative acceleration, displacement, drift and shear force were considered under earthquake ground motion excitation. For this purpose, 5-, 10- and 15-story structures with 2-bay moment resisting frames resting on shallow foundations were modeled as a group of buildings in soft soil media. Viscous lateral boundaries and interface elements were applied to the soil model to simulate semi-infinite soil media, frictional contact and probable slip under seismic excitation. The direct method was employed for fully nonlinear time-history dynamic analysis in OpenSees using 3D finite element soil-structure models with different building positions. The results showed that the responses of the grouped structures were strongly influenced by the adjacent structures. The responses were as much as 4 times greater for drift and 2.3 times greater for shear force than the responses of fixed-base models.

• Earthquakes and Structures
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• v.10 no.4
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• pp.849-865
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• 2016

Beside the invaluable advancements in constructing more secure buildings, the post-earthquake inspections have reported considerable damages. In other words, the modern buildings satisfactorily decrease fatalities but the monetary impacts still mostly remain an unsolved concern of the stakeholders, the insurance companies and society together. Therefore, the fundamental target of the researches shifted from current force-based seismic design regulations to the Performance-Based earthquake engineering (PBEE). At the moment, some probabilistic approaches, such as PEER framework have been developed to predict the performance of building at any desired hazard levels. These procedures are so time-consuming, to which many details are needed to be assigned. It causes their usage to be limited. On that account, developing more straightforward methods seems indispensable. The main objective of the present paper is to adapt an equivalent static method in different damage states. Consequently, constant damage spectrums corresponding to different limit states, soil types, ductility and fundamental periods are plotted and tri-linear formulas are proposed for further applications. Moreover, the sensitivity of outcomes to the employed hysteresis model, ductility, viscous damping and site soil type is investigated. Finally, a case study building with moment-resisting R.C. frame is evaluated based on the both of new and current methods to ensure applicability of the proposed method.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.5
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• pp.959-967
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• 1988

In this paper, 2-DOF vehicle suspension system with a semiactive on-off damper was studied for improving the ride comfort. It is known that a nonlinear hydraulic damper, which generates force proportional to the square of the relative velocity, can describe the actual fluid resisting type damper more properly than the traditional viscous damping model. On the other hand, hydraulic damper adoption in analysis makes the system nonlinear and causes difficulties to get the system response. In this work, time domain direct integration method was used to calculate system displacement and acceleration. first of all, the response of the suspension system experiencing a given road profile was optimized by Lagrangian multiplier method within the range of given damping coefficients. The appropriate on-loaf damping values were obtained by averaging the already calculated optimum damping coefficients from Lagrangian techniques. The criterion to control the on-off mechanism was determined by examining the suspension efficiency. It was found that the best out of practically applicable criteria is following the sign (positive and negative) of the multiplication of relative displacement and velocity. Judging from the theoretical calculations, it was proved that the semiactive on-off damper can increase suspension efficiency as much as 8-11% in object function.