Fluid Viscous Dampers Research Articles

Comparison of seismic responses of a jumbo-size container crane retrofitted with braces, dampers, and isolation systems

The effectiveness of six seismic retrofitting intervention schemes on an existing jumbo-size container crane is investigated. They include the use of conventional steel braces and buckling-restrained braces, fluid viscous dampers and friction dampers, lead rubber bearing isolators, and natural rubber bearing isolators with viscous dampers. The six schemes can be grouped under three main strategies, i.e., the use of different types of bracings, dampers, and isolation systems. Nonlinear response history analyses, using eight spectrally matched ground motions, were conducted on 3D models of the crane, with and without any upgrading, using SAP 2000. The results showed that with the exception of the conventionally braced crane, which produced inconclusive responses, the other two retrofitting strategies of using different types of dampers and isolation systems significantly reduced the critical seismic responses of the crane. At a target drift of one-third the original, the damping systems caused on average reduction of approximately 32%, 36%, and 98% in the base shear, stress, and uplift responses, respectively. Moreover, a significant reduction of about 65% in the stress and base shear responses and a condition of no uplift were recorded when the isolation systems were applied. The results of this study show that the isolation systems produce the best performance and therefore can be considered as the most effective seismic retrofitting technique.

Study the Comparative Effect of Different Link Dampers on G+25 High Rise Buildings in Seismic Zone IV

Abstract: The usefulness of a high-rise building equipped with different types of link dampers (such as bilinear dampers, fluid viscous dampers, and frictional dampers) for the purpose of controlling seismic vibration is discussed in this study. Due to their safe, efficient, and cost-effective design, dampers have gained a lot of popularity in recent years for the purpose of controlling vibration in structures. They are frequently employed in structural vibration control to reduce seismic risks and, with the use of passive energy dissipation devices, can enhance the dynamic responsiveness of both new skyscrapers and existing high-rise structures. The structure's structural safety and serviceability are improved, and the controlling devices stop the building from collapsing during an earthquake, thereby greatly reducing damage. This paper would discuss the high rise RCC structures (G+25), with different Link dampers for seismic vibration control and study the effect of dampers on it using ETABS software.

Metallic Yielding Dampers and Fluid Viscous Dampers for Vibration Control in Civil Engineering: A Review

Structural vibration is a widespread issue occurred in the field of civil engineering. The passive energy dissipation devices are being increasingly popular for protecting structures from external excitations due to their high performance and no need for external energy. They can be divided into displacement-dependent dampers and velocity-dependent dampers, among which the metallic yielding dampers (MYDs) and fluid viscous dampers (FVDs) are the most representative. This paper presents an overview of the MYD and FVD, aiming to reveal their defects and provide suggestions for future development. The basic concept, the mechanical models, the design approaches, and the applications in civil engineering of the two dampers are reviewed. In particular, the obstacles in application and preference in research of these two dampers are summarized, and their merits and drawbacks are further discussed. Emphatically, the strategies for improvement and future development trends are explored.

Modeling and control of helicopter flight control system with a controllable Semi-rotary fluid viscous damper

To improve the handling comfort of Helicopter Flight Control System (HFCS), an adaptive particle swarm optimization optimized variable universe fuzzy proportional-integral-derivative (APSO-VUFPID) strategy for damping force control is proposed. First of all, by the results of the controllable semi-rotary fluid viscous damper (CSFVD) mechanical tests, a hyperbolic tangent model is developed. Afterwards, an equivalent model of HFCS is established. In the next part, aiming at improving the vibration suppression performance of the joystick system, an APSO-VUFPID is proposed to generate the desired damping force in real-time. Finally, numerical simulation and experimental tests are carried out to verify the vibration reduction effect of the proposed APSO-VUFPID method with respect to passive, proportional-integral-derivative (PID), adaptive particle swarm optimization optimized proportional-integral-derivative (APSO-PID) and adaptive particle swarm optimization optimized fuzzy proportional-integral-derivative (APSO-FPID) methods. The results show that the hyperbolic tangent model can accurately describe the nonlinear mechanical characteristics of the CSFVD. Moreover, under the proposed APSO-VUFPID control method, the amplitude of acceleration and velocity of the joystick system are smaller than those obtained from passive, PID, APSO-PID and APSO-FPID methods. Therefore, the proposed APSO-VUFPID controller has better handling comfort compared to passive, PID, APSO-PID and APSO-FPID controllers and can be employed in real applications.

Parametric study and prediction models of the seismic response of single-degree-of-freedom structural systems equipped with Maxwell material fluid viscous dampers

The addition of supplemental damping through fluid viscous dampers has been widely implemented as a seismic protection system for diverse typologies of structures. Typically, fluid viscous dampers are modelled using a Maxwell material model, which accounts for the stiffness of the damper device and its support assembly. However, the influence of the different parameters involved in the design of Maxwell fluid viscous dampers on the dynamic response of damped systems subjected to transient loads has not been studied thoroughly, especially regarding the acceleration response of dynamic systems. This paper discusses the results of a parametric study of the influence of several damper's design parameters, such as the velocity exponent, the supplemental damping level, the seismic intensity, and the Maxwell material stiffness, and the interaction among them, on the seismic response of viscously damped single-degree-of-freedom structural systems. Non-linear time history analyses were carried out using the FEMA P-695 far-field ground motion set scaled to four increasing intensities. The seismic response was measured in terms of peak relative displacements, peak relative velocities, peak damper forces, peak floor absolute accelerations, and peak floor absolute acceleration response spectra. Based on the obtained seismic responses, several prediction models were proposed using Gaussian Process Regression to provide an insight into the influence of the different design parameters of fluid viscous dampers on the seismic response of viscously damped single-degree-of-freedom structural systems. The results show that the different parameters involved in the design of Maxwell fluid viscous dampers significantly influence the efficiency of damper devices and the seismic response of the single-degree-of-freedom structural systems, especially in terms of acceleration response. For particular combinations of the damper's design parameters, significantly higher floor spectral accelerations can be observed in some period ranges compared to those of control systems without dampers. Additionally, the floor absolute acceleration response spectra exhibit a stiffening effect caused by the implementation of fluid viscous dampers, shifting peak floor spectral accelerations to shorter periods. The magnitude of the stiffening effect is proved to be correlated to the Maxwell material stiffness value.

Seismic Response Control of High-Rise Mass Varied Structures Using Linear Fluid Viscous Damper

Abstract: Seismic event induces undesirable motion in buildings, energy dissipation systems in civil engineering are indeed needed. There is a mix of structures with passive energy dissipation supplied by Fluid Viscous Dampers systems (FVD). This technology is increasingly being utilized to improve seismic protection for both existing and new structures. The findings of the FVD systems are investigated in order to compare the structural response with and without this device of energy dissipation compared for low and high rise structures, the damper installed at different storey and varying the coefficient of damping (Cd) has been focused in this paper which provides an insight when the variation of Cd and its locations,. The findings of the FVD's impressive ability to increase the structure's dissipative capabilities without increasing its stiffness. In the case of high rise FVD performance has been evaluated through the top storey displacements which will allow for a conclusion. Keywords: Coefficient of Damping, Fluid Viscous Damper, High Rise Buildings, Seismic Response, Tall Structure

Some observations on energy demand spectra for single-degree-of-freedom systems equipped with fluid viscous dampers

The ability of structural elements to absorb input energy through inelastic deformation and supplemental damping is a primary factor in determining structural damage during earthquake excitation. This study proposes an energy methodology for the seismic evaluation of single-degree-of-freedom (SDOF) systems, considering the effect of fluid viscous dampers (FVDs). The FVD is characterized by supplemental damping ratio, [Formula: see text], and velocity power [Formula: see text]. A computer algorithm is developed for the numerical simulation of SDOF systems using nonlinear time history analysis, which is verified through a number of validation examples. This study focuses on issues related to input and hysteretic energies [Formula: see text] with particular emphasis on near-field records and their interrelationship with seismic response demand, which is defined as non-dimensional indices for SDOF systems without FVD and those equipped with FVD. The energy indices ([Formula: see text] and [Formula: see text]) are the ratios of input and hysteretic energies to maximum displacement demand, respectively. The results show that the natural period [Formula: see text], ductility level [Formula: see text], [Formula: see text], and [Formula: see text] have a significant effect in the determination of energy spectra [Formula: see text]. The non-dimensional [Formula: see text] is a more stable and reliable indicator than [Formula: see text] to quantify the damage potential of ground motion. Finally, the observations of the energy approach provided in this study indicate that it can be used as a useful tool for developing energy-based guidelines for structures incorporating FVDs.

Performance enhancement of FPS-isolated buildings using an inerter-based damper: Stochastic seismic analysis and optimization

Enhancing the seismic performance of based-isolated structures during a major earthquake event using inerter-based dampers emerges as a prominent research direction. However, analysis and optimization of based-isolated structures incorporated with inerter-based dampers considering both system nonlinearity and excitation uncertainty have rarely been reported. An electromagnetic inertial mass damper (EIMD) is a high-performance passive damper that consists of an inerter element and a damping element in parallel, and its superior control performance has been validated when applied to stay cables and frame structures. This paper presents a stochastic seismic analysis and parameter optimization of a friction pendulum system (FPS)-isolated structure with an EIMD considering the Kanai-Tajimi earthquake model. Considering the nonlinear damping of the FPS system, we derive the semi-analytical solutions of the FPS-isolated structure with an EIMD under stationary stochastic excitations based on a two-degree-of-freedom model using the statistical linearization technique. The effect of the EIMD on the FPS-isolated structure is systematically investigated via parametric study. A numerical procedure is proposed for optimizing the parameters of the EIMD and the FPS for minimizing the seismic response variances. Numerical simulation of a seven-story FPS-isolated building subjected to both artificial and real seismic excitations illustrates the effectiveness of the optimization procedure based on the semi-analytical solutions. Numerical results also reveal that the EIMD is capable of reducing both the base floor responses and superstructure responses, which outperforms tuned inerter dampers and conventional fluid viscous dampers. This study might shed light on the applications of inerter-based dampers in based-isolated structures in the years to come.

Risk-Based Optimal Design of Seismic Protective Devices for a Multicomponent Bridge System Using Parameterized Annual Repair Cost Ratio

Base isolators and fluid viscous dampers are viable protective devices that have been commonly considered in the seismic protection of civil engineering structures. However, the optimal design of these devices remains a tedious and iterative undertaking due to the uncertainty of ground motions, the nonlinear behavior of the structure, and its change of dynamic characteristics (i.e., effective stiffness and damping ratio) under each new design. The optimal design problem becomes more challenging concerning a multiresponse bridge system where conflicting damage potential is often expected among multiple bridge components (e.g., column, bearing, shear key, deck unseating, foundation). In this respect, this study develops a risk-based optimization strategy that directly links the expected annual repair cost ratio (ARCR) of the bridge to the design parameters of base isolators and fluid dampers. This strategy is achieved by devising a multistep workflow that integrates a seismic hazard model, a design of experiment for bearings and dampers, a logistic regression towards parameterized component-level fragility models, and a bridge system-level seismic loss assessment. The developed ARCR is parameterized as a convex function of the influential parameters of seismic protective devices. As such, optimal bearing and damper designs can be pinpointed by directly visualizing the global minimum of the parameterized ARCR surface. The optimal design is carried out against a typical reinforced concrete highway bridge in California that is installed with the fluid dampers and three types of widely-used isolation bearings—the elastomeric bearing, lead-rubber bearing, and friction pendulum system. It is shown that optimal design parameters can be obtained to significantly reduce the expected ARCR of the bridge, whereas combining optimally designed bearings and dampers can provide the minimum seismic risk.

Seismic Retrofitting of RC Frame Structure Using Energy Dissipation Device

Abstract: This study examines the performance-based design of structure that is increasing commonly in earthquake resistance design. to ensure any structure possess earthquake resistant design, certain minimum performance objective is desired at different level of seismic excitation. With the help of some devices, Lowto medium rise buildings are performing well forthe seismic actions. In the present work, originally deficient RC frame is analyzed with static analysis and after this static non- linear analysis is performed in which suitable energy dissipation devices are installed sequentially. first analyzed with Viscous fluid Damper then Lead- rubber isolator is used has designed as per performance-based design criteria of G+6 RC frame building. These models are analyzed for important residential use and located at seismic zone IV. Linear static and nonlinear static methods are used to analyze the structure with help of CSI ETABSv18 software. Results which are discussed is minimum performance level, story drift,performance point and performance objective. After analysis of results, structure which is installed with Led-rubber bearing isolator is performed well during an earthquake and satisfy with desired minimum performance level. In case of viscous fluid damper, it is not satisfactory to achieve desired minimum performance up to this extent it helps to reduce floor acceleration.

Theoretical and experimental investigation on the seismic performance of a novel variable-damping viscous fluid damper

This paper presents a novel three-stage variable-damping-coefficient viscous fluid damper (VCVFD) and investigates its effectiveness in mitigating the seismic structural response. The concept and design of the displacement-dependent VCVFD were based on the equations for one-dimensional viscous flow in the damper orifice. A series of performance tests on VCVFDs were conducted to investigate the mechanical behaviour of the dampers with different design parameters under various loading conditions. The damping force increases more significantly than in the conventional viscous fluid damper (VFD) when the operating displacement is larger, and the expected effect of variable damping is achieved. A smaller gap height is more beneficial to energy dissipation in the VCVFD. Moreover, the hysteresis loop of the VCVFD was consistent with the theoretical results. To validate the effectiveness of the VCVFD in structural control, shaking table tests of two-storey steel frames equipped with VCVFDs under different seismic intensities were conducted. VCVFD can slightly increase the natural frequencies of the steel frame and significantly increase the structural damping ratio. The effectiveness of the VCVFD in mitigating the structural acceleration under low earthquake intensities was not prominent, but as the earthquake intensity increased, the acceleration amplification factor decreased. The added damping contributed by VCVFDs can significantly reduce the displacement response. It is concluded that with reasonable damping structural design, the VCVFD can achieve an almost similar mitigation effect as VFD in low-intensity earthquakes, whereas the VCVFD can provide higher damping under high-intensity earthquakes.

Influence of Beams Distribution on the Dynamic and Seismic Linear Response of RC Frame Buildings

The present study compares the dynamic properties and seismic performances offered by reinforced concrete frame structures characterized by different beams distribution. The understanding of the influence of beams distribution on spatial frames is not only useful when dealing with the seismic vulnerability assessment of existing buildings that may show unusual layouts of beams, such as alternating beams at each storey, but also when facing the design of new buildings with fluid viscous dampers for which some structural flexibility is required. A systematic study is described in this paper. Four (2-, 3-, 6-, and 10-storey) regular frame buildings with rectangular plan are considered as reference structures. Different models are developed according to various layouts of the primary beams, exploring alternatives to the full three-dimensional organisation of beams and frames. For instance: beams placed along the longitudinal direction at the odd storeys and placed along the transversal direction at the even storeys, and vice versa; alternating beams every one and two storeys; beams just placed along one direction. Modal analysis has been conducted to evaluate the influence of beams distribution on the dynamic properties (periods of vibration and modal participating mass ratios). Response spectrum analysis and linear time-history dynamic analysis have been carried out to assess the effects of beams distribution on the fundamental seismic response parameters (shear forces, bending moments, top-storey displacements, interstorey drifts, and floor accelerations). On the contrary of what could be expected, the results indicate that structures with beams alternating every storey may show interesting advantages in terms of reduced total base shear, almost comparable bending moments and accelerations, within a still balanced overall behaviour along the two directions, with respect to the complete three-dimensional frame. Two effects are recognized: the period effect and the static scheme effect. The former acting basically on the storey shear forces; the latter acting mainly on the bending moments.

Preliminary Design of Seismic Isolation Systems Using Artificial Neural Networks

This works attempts to implement artificial neural networks (ANN) for modeling Seismic-Isolation (SI) systems consisting of Natural Rubber Bearings and Viscous Fluid Dampers subject to Near-Field (NF) earthquake ground motion. Fourteen NF earthquake records representing two seismic hazard levels are used. The commercial analysis program SAP2000 was used to perform the Time-History Analysis (THA) of the MDOF system (stick model representing a realistic five-story base-isolated building) subject to all 14 records. Different combinations of damping coefficients (c) and damping exponents (α) are investigated under the 14 earthquake records to develop the database of feasible combinations for the SI system. The total number of considered THA combinations is 350 and were used for training and testing the neural network. Mathematical models for the key response parameters are established via ANN. The input patterns used in the network included the damping coefficients (c), damping exponents (α), ground excitation (peak ground acceleration, PGA and Arias Intensity, Ia). The network was programmed to process this information and produce the key response parameters that represent the behavior of SI system such as the Total Maximum Displacement (DTM), the Peak Damper Force (PDF) and the Top Story Acceleration Ratio (TSAR) of the isolated structure compared to the fixed-base structure. The ANN models produced acceptable results with significantly less computation. The results of this study show that ANN models can be a powerful tool to be included in the design process of Seismic-Isolation (SI) systems, especially at the preliminary stages.

Probabilistic performance assessment of seismically excited buildings with semi-active fluid viscous damper

Probabilistic performance assessment of seismically excited buildings with semi-active fluid viscous damper

Performance evaluation of seismically isolated buildings near active faults

AbstractThis paper investigates the collapse risk of seismically isolated buildings that are designed by the procedures of the ASCE/SEI 7‐16 standard for sites within 5 km of the active fault that controls the hazard. The study is based on six‐story perimeter frame buildings designed with special concentrically braced frames for a location in California. The seismic isolation systems considered in this study are comprised of either: (i) triple friction pendulum bearings with high friction coefficients at the sliding interfaces, (ii) triple friction pendulum bearings with low friction coefficient at the sliding surfaces and enhanced with fluid viscous dampers, or (iii) triple friction pendulum bearings with low friction coefficients at the sliding surfaces. The paper demonstrates that the seismically isolated buildings designed per Section 17.3.3 in ASCE/SEI 7‐16 standard, but with either increased isolator displacement capacity or increased superstructure strength by comparison to the minimum required, can achieve an acceptable collapse risk. It is also demonstrated that the seismic isolation systems that have the best collapse performance for far‐field motions are not necessarily the best for the near‐field pulse‐like ground motions.

EARTHQUAKE RESPONSE STUDY OF MULTI-STORIED RCC BUILDING WITH FVD ON SLOPING GROUND

Damping performs essential function in format of earthquake resistant structures, which lower the change of the shape when they are subjected to lateral loads or earthquake. In the existing study fluid viscous dampers (FVD) are used to consider the response of RCC buildings on sloping ground. The important challenge of a structure is to endure the lateral loads and switch them to the foundation and to control the story displacement. In order to make structure earthquake resistant, (FVD) have been used. The building is modeled in ETAB 2018 and modeled with different location of FVD. After the study results show building with fluid viscous dampers (FVD) at diagonal bracing shows better performance.

Seismic performance of a continuous bridge with winding rope device activated by a fluid viscous damper

The seismic requirements of piers with fixed bearings (the fixed pier) for continuous girder bridges are relatively high, while the potential seismic capabilities of piers with sliding bearings (the sliding piers) are not fully utilized. To solve this contradiction, a new type of winding rope shock absorption device activated by a fluid viscous damper (WRD-D) was proposed. The WRD-D was installed on the top of the sliding piers, and the both ends of a fluid viscous damper were connected to the superstructure by winding ropes. During an earthquake, the damping force rises with the increase of relative speed between the sliding piers and the superstructure, activating the WRD-D and producing large frictional resistance, subsequently causing the sliding piers and the fixed pier to bear the seismic load cooperatively. In this study, the working mechanism of the WRD-D was researched. The shaking table test of a scaled continuous girder bridge model employing the WRD-D was conducted. The test results reveal that the WRD-D can effectively reduce the seismic requirements of the fixed pier and the superstructure displacements.

Energy dissipation demand and distribution for multi-story buildings with fluid viscous dampers

The seismic response of structures with fluid viscous dampers (FVDs), which is a predominant type of structural control techniques, can be analysed from the perspective of energy. In such structures, the imposed seismic energy is mainly dissipated by the structural plastic energy, EP, and the energy dissipated by FVDs, Ed2, which quantify the structural cumulative damage and FVD’s seismic reduction effect, respectively. Research conducted in the past focuses on investigating the EP demand of systems without supplemental damping devices, but little knowledge is available for the EP and Ed2 demand in multi-story buildings equipped with FVDs. To fill this gap, this paper conducted a comprehensive investigation based on four steel-moment resisting buildings with different height (3-, 6-, 9-, and 20-stories, respectively) equipped with linear or nonlinear FVDs. The effect of structural property and FVDs properties, characterised by the supplemental damping ratio ξadd and velocity power α, on the EP and Ed2‘s overall demand and distributions among stories were illustrated. The results indicate coupling effects of structural property, ξadd and α, on the EP and Ed2 demands. In most cases, the increase of ξadd and the decrease of α can reduce the EP demand and increase the Ed2 response. However, the increasing of ξadd is not effective if it is larger than 20% and the FVDs with α = 0.3 are not recommended in relative high-rise buildings. The distribution pattern shows a trend of linearly decreasing along the height, but those in the high-rise buildings are disturbed by high-mode effects.

Contribution of fluid viscous dampers on fatigue life of lattice-type offshore wind turbines

Given the recent developments in wind energy generation technology, offshore wind turbines have been widely used to exploit offshore wind energy. Supporting structures of offshore wind turbines play an important role in correct operation of wind turbines and their operational life. Supporting structures will experience millions of lateral load reversals due to wave- and wind-induced vibrations. Because of the stress concentration, more fatigue damages are expected at the structural joints. Supporting structures of offshore wind turbines have commonly small inherent damping and it is believed that because additional viscous damping can reduce structural vibrations and result in less stress concentration at the joints. In this study, vertically oriented fluid viscous dampers are used to increase fatigue life of a full-height Lattice-type Offshore Wind Turbine (LOWT). Obtained results indicated that the use of fluid viscous dampers significantly delayed fatigue failure and increased fatigue life of structural joints by up to 3 times.

Analysis of high-rise building by using fluid viscous dampers

Fluid viscous dampers are dynamic actuators that when stroke, it absorb the energy that by tectonic disturbances, wind absorption, or heat on a structure. Every multi-story building structure that is subjected to ground motion in daily life needs to be studied to determine how it responds because this is a common issue for construction. The structure's foundation is vibrating due to the earthquake. Buildings oscillate as a result of these vibrations, which could seriously harm the structure and observe the earthquake behaviour of structures with and without Fluid Viscous Dampers (FVD) and conventional Reinforce Concrete (RC) moment-resistant frames. The analysis takes place on displacement changes that caused by the addition of FVD in the structure and reduction in base shear in reinforced concrete structures after installing FVD and by using response spectrum and time history analysis. It compares the findings of storey displacement, storey stiffness, base shear, and storey drift assessments. This research provides information on several studies done on multi-story buildings while taking into account the various factors. The examination on vibration characteristics of a G+20 structure with and without a viscous damper is presented in the proposed work. Practically all multi-storeyed buildings must be analysed as three-dimensional systems, according to the current edition of the IS: 1893–2016. The building floor plans may be seen as asymmetrical and the hill slope topography of India is typically geologically stable.