Fluid Viscous Dampers Research Articles

Seismic Analysis of Irregular Diaphragm Reinforced Concrete Building with Fluid Viscous Dampers

Abstract: Fluid viscous damper is the most commonly used tool for controlling structures’ responses. Fluid viscous dampers with different construction technologies are applied in order decrease the responses of structures to the seismic vibrations. During the recent years, controlling structure has turned into a scientific technology to protect structures against wind and earthquake loads. In the present study linear dynamic and non-linear static analysis was adopted to assess the seismic performance of an irregular diaphragm building. Building with and without fluid viscous damper have been taken.The outcomes of the study will be beneficial to assess the performance of existing building vulnerable to seismic loads after the installation of fluid viscous dampers.

Enhancing the Seismic Response of Residential RC Buildings with an Innovative Base Isolation Technique

The prediction of the magnitude and impact of forthcoming earthquakes remains an elusive challenge in the field of science. Consequently, extensive research efforts have been directed toward the development of earthquake-resistant design strategies aimed at mitigating building vibrations. This study focuses on the efficacy of fluid viscous dampers (FVDs) in augmenting the seismic response of a low-rise residential reinforced-concrete building, which is base-isolated, using high–damping rubber bearings (HDRBs). The structural analysis employs a non-linear approach, employing ETABS v16 software for building modeling and conducting non-linear dynamic analysis using artificial accelerograms specific to Algeria. Three distinct connection configurations to the building’s base are investigated: (1) a fixed-base structure; (2) a structure isolated by HDRBs; and (3) a structure isolated utilizing a novel parallel arrangement of HDRBs in conjunction with FVDs. Comparative evaluation of these configurations reveals noteworthy findings; the results demonstrate that the base isolation system, comprising HDRBs and FVDs, significantly diminishes the base shear force by over 80% and reduces acceleration by 54% while concurrently increasing displacement by 47%. These findings underscore the effectiveness of incorporating FVDs in conjunction with HDRBs as a means to enhance the seismic response of reinforced concrete buildings. This study showcases the potential of such structural analyses to contribute to the development of earthquake-resistant design approaches, providing valuable insights for architects and engineers involved in constructing resilient buildings in seismically active regions.

Effect of damping on the seismic response of long-period structures considering crossover phenomena

This study systematically investigates the effect of damping on the seismic response of long-period structures. For long-period single-degree-of-freedom systems, the addition of damping would on average reduce the relative deformation and velocity, but increase the absolute acceleration. However, the crossover phenomena, i.e., the increase of the damping leads to the larger structural response, would occur in the spectral displacement or velocity of some certain ground motions, which is more pronounced with the increase of structural periods. The percentage of ground motions developing crossover phenomena attends approximately 100%, 40% and 20% for the acceleration, velocity and displacement, respectively, at very long structural periods. For long-period multiple-degree-of-freedom systems, illustrated by two cable-stayed bridges, the addition of linear viscous fluid dampers (VFDs) would averagely lead to the reduction of the displacement responses, but the crossover phenomena might also occur. It is recommended that VFDs be implemented to cable-stayed bridges as the deck longitudinal displacement is generally reduced and the deck longitudinal vibration is damped out during a short time compared to the uncontrolled case. However, the damping coefficient of the VFDs needs to be restricted such that the damping force is limited to a reasonable range, and significant response increments of some components are avoided.

On simultaneous analysis and design optimization for seismic retrofitting with fluid viscous dampers

On simultaneous analysis and design optimization for seismic retrofitting with fluid viscous dampers

Dynamic Response of a Long-Span Double-Deck Suspension Bridge and Its Vibration Reduction

This paper presents a dynamic analysis of a long-span double-deck suspension bridge subjected to random traffic loading using a Finite Element (FE) model. During this study, the influence of various traffic parameters, such as vehicle speed, traffic volume, traffic weight, and the location of the passing girder, on the longitudinal movement of the girders was investigated. The results reveal that schemes with double girders passing can lead to greater longitudinal displacement of the girder as compared to a long-span bridge with a single passing girder. However, the incorporation of fluid-viscous dampers at the ends of the girders significantly reduces the displacement range of each node. For instance, at the left end of the bridge, the original model (without dampers) exhibits a displacement range of approximately 0.01–0.056 m, whereas the constrained model (with dampers) shows a range of 0.025–0.033 m. A quantitative analysis demonstrates that higher damping coefficients (or smaller damping exponents) can further mitigate the girder’s movement.

Full-scale shaking table tests and numerical studies of structural frames with a hybrid isolation system

A typical hybrid isolation system (HIS) incorporating natural-rubber bearings (NRBs) and nonlinear fluid viscous dampers (NFVDs) is proposed for seismic protection of critical equipment in nuclear power industrial buildings (NPIBs) under strong earthquakes. Design procedure with a parametric study towards the HIS considering various stiffness and damping values is first investigated via extensive nonlinear time history analyses. Then a preliminary recommendation for the specific structural demands of the considered system is proposed to direct the seismic design for both member- and system-level tests. Through a suite of full-scale shaking table tests on two typical NPIBs, the efficiency and reliability of the HIS are verified, in comparison to the structure with conventional rubber isolation system (RIS). The shaking table test results exhibit a superior behavior of the HIS in structural dual control strategies, i.e., transient acceleration control in critical equipment and bearing deformation control. Also, the HIS presents stable and resilient performances in both negligible residual bearing deformation and undetectable damage to structural/nonstructural components (containing the seismic isolated devices, i.e., NRBs and NFVDs). Finally, a three-dimensional finite element (FE) structural model and a single-degree-of-freedom (SDOF) system are successively developed to simulate the dynamic responses of the test structures. The well-validated SDOF FE model, serving as a reliable alternative for the isolated NPIBs, can be further utilized to facilitate practical design.

Seismic Behavior of the Combined Viscous-Steel Damping System for a Long-Span Suspension Bridge Considering Wave-Passage Effect

This study investigates the working mechanism and seismic behavior of the Combined Viscous-Steel Damping System (CVSDS) considering the longitudinal wave-passage effect. In the CVSDS, the operational status of the fluid viscous damper (FVD) and the steel damper (SD) can be switched by the fuse–lock device (FLD), which is triggered by the output force of the FVD. The configuration and working mechanism of CVSDS are introduced in detail. A test model is manufactured and examined by cyclic tests to verify its fusing–locking function during cyclic motions. The numerical model of CVSDS is proposed based on the experimental result. The fusing–locking behavior and seismic reduction effectiveness of CVSDS installed in a long-span bridge is analyzed, in which the wave-passage effect is considered. The results show that the fuse–lock function under dynamic loading can be achieved by the proposed FLD. The occurrence condition of the locking mechanism activation depends on the viscous damping force. The traveling wave will induce a delay of the locking time, cause large locking intervals between CVSDSs installed at different positions, and lead to a larger required moving capacity of the CVSDSs. The mitigation effectiveness of CVSDS is significantly reduced due to the wave-passage effect.

Seismic Control of a Concrete Bridge with Hybrid Passive Control Devices

Abstract: This study focuses on the seismic response of a three-span deck slab RCC T-Girder bridge with and without LRB (Lead Rubber Bearing) and in combination with LRB and FVD (Fluid Viscous Damper). The bridge is subjected to AASHTO, IRC design standards, and IRC Class A vehicle load. Linear time history analysis using CsiBridge and SAPfire is conducted to assess the bridge's seismic behavior. Excessive deck displacement, which can lead to deck failure and bridge closure, is a key concern. The study utilizes finite element analysis with Csibridge and incorporates viscous dampers throughout the bridge. The findings show that the presence of supplemental dampers significantly reduces pier top displacements. Base shear, deck displacement, pier response, and structural time period are the primary response parameters examined. The effectiveness of different isolation system configurations is compared to the non-isolated bridge in terms of these response characteristics. The study offers suggestions for design improvements to enhance the structure's performance.

Exploring the impact of excitation and structural response/performance modeling fidelity in the design of seismic protective devices

The design of seismic protective devices (SPDs), such as fluid viscous dampers (VDs), and inertial vibration absorbers (IVAs), requires the adoption of appropriate models for: (i) the earthquake excitation description (e.g. stochastic stationary/non-stationary versus recorded ground motions); (ii) the seismic structural response estimation (e.g. linear versus nonlinear/hysteretic); and (iii) the seismic performance quantification (e.g. average response versus risk-based performance description). This paper pursues a novel, detailed investigation of the impact of modeling fidelity in the design process of SPDs, by examining different combinations of models with different levels of sophistication for each of the aforementioned aspects. In this manner, a large model hierarchy is established, resulting in multiple SPD design variants. A bi-objective optimal design formulation is adopted, considering the structural vibration suppression (building performance) and device control forces as distinct, competing performance objectives (POs). Comprehensive comparisons are reported for a 3-storey and a 9-storey steel benchmark building, equipped with distributed VDs in all floors and with different types of single-device IVAs including the tuned-inerter-damper (TID), the tuned-mass-damper-inerter (TMDI) and the tuned-mass-damper (TMD). An innovative methodological approach is established to gauge the impact of the model fidelity by examining the deviation of POs achieved by lower fidelity SPD designs versus the Pareto-optimal fronts corresponding to POs consistent with the higher fidelity assumptions. The study overall stresses that that the use of lower fidelity models may provide sub-optimal performance in certain settings, and that comparison across the model hierarchy can be leveraged to obtain key insights of the SPD behavior. Additional key findings pertain to the robustness characteristics of the different type of SPDs to the modeling assumptions utilized for the device design.

Modelling efficiency of fluid viscous dampers positioning for increasing tall buildings' Resilience to earthquakes induced structural vibrations

Due to limited space, it is now necessary to create higher structures in metropolitan areas. However, as a building's height increases, its natural frequency decreases, which in turn causes it to respond more quickly to dynamic loads like Earthquakes. The building's and its residents' safety are gravely jeopardised by this. Installing fluid viscous dampers in the structure is a popular solution to this issue since they are efficient at controlling vibration and stabilizing the structure under dynamic loads. The purpose of this research is to assess the efficiency of fluid viscous dampers at different placements in reducing earthquake-induced structural vibrations. The findings are compared for three distinct damper placement scenarios: alternately on all stories, on all stories, and on three levels (top, bottom, and center) for a G+20 story framed building. The best model has been compared by two conventional damper placements: first ten stories continuous and first ten stories alternate. The performance of the structure has been assessed in terms of displacement, drift, and shear values during the study. The findings prove that the displacement, drift, and shear values of the structure under Earthquake loads are decreased by the employment of fluid viscous dampers. The most efficient way to lessen the building's seismic reaction is to install dampers on every story. The results of this research may be used to improve the seismic performance of structures and provide useful insights into tall building design and construction in Earthquake-prone locations.

Investigating the effectiveness of fluid viscous damper in reducing the effect of seismic sequence on steel bending frame designed on type c soil

Aftershocks can always cause the collapse of structures damaged by the main earthquake. In this article, the seismic performance of an 8-story steel bending frame designed in c-type soil was first subjected to the seismic sequence of an earthquake and an aftershock, and then the same building with the addition of a fluid viscous damper (Fluid Viscous Damper) was evaluated. The results showed that the seismic performance of the studied frame under the effect of severe aftershocks with the presence of a liquid viscous damper is very different from the case without FVD. For example, the maximum displacement of the structural floors was reduced by 60% compared to the case without a damper. It was also found that while most of the aftershocks in buildings without dampers cause a significant increase in the permanent displacement of the roof, in the presence of dampers, this amount has decreased significantly, although in general, the damage caused by the effect of aftershocks on the building is much more az It will be from a state in which the structure is only subjected to the main earthquake

Topology and Sizing Optimization of Truss-Like Pedestrian Bridges with Viscous Dampers and Inerters

The design of footbridges has begun to receive more attention in recent years due to cases in which undesirable vibrations occurred. The utilization of passive energy dissipation systems to control bridge responses has become popular as a remedy for this matter. This paper proposes the use of inerters to mitigate pedestrian bridge vibrations, and explores their potential. This is done by presenting a topology and sizing optimization methodology for pedestrian bridges equipped with fluid viscous dampers and inerters. Planar truss-like bridges are examined, loaded under dynamic and static loads. All constructive elements’ sizes (including dampers) serve as continuous design variables. The objective is to minimize a cost function of the bridge. The optimization process is constrained by demanding responses of interest not to exceed allowable values, along with global and local buckling. A first-order gradient-based optimization algorithm is adopted to lessen the computational effort. Lastly, a discretization postprocess is offered to lead to discrete designs of relevant design variables, such as steel cross sections. The results shed light on the advantages of combining inerters in pedestrian bridges.

Performance and protection of pre-engineered buildings subjected to blast and earthquake excitations

A pre-engineered building (PEB) refers to a building which is pre-designed at a factory using some simulation and modelling software as per the specifications, codes and the loads that act on the structure before the production of the building components and then finally assembled at site thereby reducing the completion time. In the current study, a case study of an existing PEB structure subjected to wind analysis has been investigated. The main objective of the present study is to evaluate the retrofitting ability of passive control dampers installed in the pre-engineered industrial building subjected to earthquake and blast phenomenon. The study investigates the effectiveness of vibration control techniques in the form of passive dampers in improving the performance of PEB structure subjected to blast and earthquake using fluid viscous dampers. The study also discusses the impact of different damper placement techniques on the structural performance of PEB structure subjected to blast and earthquake loading. Primarily three damper placement techniques are incorporated in the present study, namely single diagonal, V-shaped damper, and inverted V-shaped damper. The study also evaluates the optimum fluid damper properties, namely damping coefficient and damping exponent, in mitigating the blast and earthquake responses of the selected industrial building. The structural performance of PEB structure has been studied using finite element tool considering the nonlinear analysis and comparing the structural responses for with and without damper conditions. The V-shaped and inverted V-shaped damper placement techniques are the most effective approach in resisting the damaging effects against blasts and earthquakes for the selected PEB structure in comparison with the conventional diagonal braced dampers. The study reports reductions in structural displacements and brace forces in the range of 54–68% and 70–90%, respectively, when installed with V-shaped fluid viscous damper.

Effect of seismic sequences on behavior of mid-rise steel moment-resisting frames equipped with fluid viscous dampers

This study aims to investigate the seismic response of mid-rise steel frames equipped with fluid viscous dampers under seismic sequences. For this purpose, 4-, 6-, and 8-story steel frames with and without fluid viscous dampers are analyzed under sequences of main shock and after shock, both with near and far field acceleration records. Thus, sets of 20 near-field and 20 far-field time histories are selected, each containing the main-shock and an after-shock. Using nonlinear dynamic analysis, the responses of the frames are calculated and plotted in various diagrams. Output parameters of displacement, interstory drifts, base shear, absolute acceleration and velocity are extracted and compared. Results show that viscous dampers significantly decrease structural responses comparing to the frames without damper. Also, structural responses have increased under combination of main-shock and after-shock which shows the important role of after-shocks in structural damages. Responses to near field record are also generally greater than far field ones.

Review on self-centering damper for seismic resilient building structures

In recent years, major earthquakes in China, Chile, New Zealand and Japan caused many building structures severely damaged, which must be overhauled or rebuilt. Therefore, how to improve the seismic resilience of building structures has been widely concerned. The energy dissipation dampers are proposted to install in some parts of the structure to produce large damping and dissipate much seismic energy input. While, the disadvantage of these traditional dampers is that they cannot automatically restored to the original position after the earthquake, and the residual deformation may result in huge economic losses. In recent years, researchers proposed to combine self-centering devices with traditional dampers to obtain self-centering capacity in addition to energy dissipation capacity, and the self-centering dampers can effectively avoid post-earthquake damage of the structure. This paper first reviews the mechanical characteristics and development of traditional dampers, including metal yield dampers, friction dampers, viscoelastic dampers, viscous fluid dampers, etc. Then, the research of self-centering dampers is summarized according to the types of self-centering devices, including shape memory alloy (SMA) type, steel tendon and strand type, and mechanical spring type. Further, the experimental research and seismic design methods of structures with self-centering dampers are reviewed, as well as the classic engineering applications of different dampers. Finally, the future directions need to be concerned in the further research are mentioned, which is benefical to the future engineering popularization and applicaition of self-centering dampers.

On the Influence of Unexpected Earthquake Severity and Dampers Placement on Isolated Structures Subjected to Pounding Using the Modified Endurance Time Method

The aim of this study is to investigate the performance of isolated structures by considering the possibility of impact under severe earthquakes. In the design of isolated structures, the required displacement capacity is determined based on the considered earthquake hazard level. However, there is a possibility of an impact caused by moat walls or adjacent structures under severe earthquakes. Dampers are used in this study to improve the performance of structural and nonstructural components. In this regard, three isolated structures (6, 9, and 12 stories) equipped with Triple Friction Pendulum Isolator (TFPI) are designed under earthquake hazard levels of BSE-1 with return periods of 475 years. Based on the different positions of these three structures relative to each other, four scenarios are defined to investigate the effect of impact. Modified endurance time (MET) method, as a cost-efficient nonlinear time history analysis method, is employed for structural evaluation under variable earthquake hazard levels. The placement of dampers is also taken into account in evaluating the effect of dampers. Therefore, the structures have been retrofitted once by adding damping and stiffness devices (ADAS) on the stories and once by adding fluid viscous dampers (FVD) at the isolated level. Results indicate that structures might collapse under earthquake hazard levels of BSE-2 with return periods of 2475 years. This matter is influenced by the adjacency of two isolated structures next to each other, and the severity of this fact depends on the height of the structures and the displacement capacity of the isolators so that the tall, isolated structures have decreased the performance of the adjacent shorter isolated structure. Moreover, the placement of dampers has a significant influence on the performance of structural and nonstructural components, depending on the reason for the impact.

Enhancing Seismic Resilience of Existing Reinforced Concrete Building Using Non-Linear Viscous Dampers: A Comparative Study

After the catastrophic destruction of the October 2005 Kashmir earthquake, the first building code of Pakistan was developed in 2007. The sole purpose of the building code of Pakistan (BCP) was to incorporate advancements in earthquake-resistant design to fortify structures and ensure the safety of citizens against future seismic events. After 2007, the BCP was not revised till 2021 to include the changes over time. However, the recently updated version of BCP 2021 highlights that the seismicity of many regions in Pakistan is high, which is not truly reflected in the BCP 2007. Therefore, the advancements in earthquake-resistant design due to the growing concerns about the potential risks of seismicity in the region have been incorporated into the updated version of the BCP. However, there are concerns among researchers that many structures designed on the 2007 code may need seismic fortification. Therefore, the current study focuses on the seismic fortification of existing systems that were developed using previous codes. Non-linear viscous fluid dampers are used to improve the seismic resilience of existing structures. This study compares the seismic performance of an existing reinforced concrete building with and without non-linear viscous dampers and subjected to a non-linear dynamic analysis. The performance of the building is evaluated in terms of story displacement, story drift, story acceleration, and energy dissipation mechanisms. Adding the non-linear fluid viscous dampers in the structure caused a decrease in the inter-story drift by around 31.16% and the roof displacement was reduced by around 36.58%. In addition to that, in a controlled structure, more than 70% of energy was dissipated by the fluid viscous dampers. These results indicate that adding the non-linear fluid viscous dampers to the existing structure significantly improved the vibration performance of the system against undesirous vibrations. The outcomes of this study also provide a very detailed insight into the usage of non-linear viscous dampers for improving the seismic performance of existing buildings and can be used to develop effective strategies to mitigate the impact of seismic events on already built structures.

Theoretical and Experimental Analysis of a Winding Rope Fluid Viscous Damper

This paper investigated a winding rope fluid viscous damper (WRFVD) that uses the frictional amplification mechanism of a winding rope to obtain the operating characteristics of a viscous damper-like device. The WRFVD combined the advantages of fluid viscous dampers and friction dampers. It not only retained the mechanical characteristics of the fluid viscous damper but also reduced manufacturing costs. First, the construction and working principles of the WRFVD were introduced. A theoretical model that could accurately simulate the hysteretic characteristics of the damper was derived. Then, a series of dynamic tests were performed on six prototypes of the WRFVD. The dynamic performance under different displacement amplitudes and device parameters was analyzed based on the test results. In addition, the theoretical model was validated by experimental results. Finally, a series of parametric analyses of the WRFVD were performed. The experimental results showed that the WRFVD is a type of velocity-dependent damper with smooth and plump hysteretic curves under sinusoidal displacement excitation. Fatigue loading tests showed that the WRFVD had excellent fatigue resistance capacity and stable operational performance. The established theoretical model was reasonable and satisfactorily reproduced the hysteretic properties of the WRFVD. The parametric analyses showed that it was not recommended to improve the performance of the WRFVD by the method of adjusting the damping coefficient and pretightening load. It was reasonable to adjust the performance of the WRFVD by setting a smaller velocity exponent, an appropriate winding turn of winding ropes, and a suitable friction coefficient.

Comparative study of buckling restrained braces and fluid viscous damper applied in an RCC structure following pushover analysis

Energy dissipators are widely used to enhance structural performance against wind and seismic activities. Since India is an earthquake-prone country, displacement-dependent (an example: buckling restrained bracing), and velocity-dependent (an example: fluid viscous damper) both types of energy dissipators are becoming more well-known and widely used to lessen the effects of seismic occurrences. Although most of the study about the application and performance evaluation of energy dissipators like buckling restrained braces (BRB) and fluid viscous damper (FVD) were based on steel and composite structure, reinforced cement concrete (RCC) building makes up the majority of structures in India, and a large number of RCC building structure are not capable to resist damage due to seismic activity. Additionally, nonlinear static analysis-based comparative information concerning BRB and FVD is very few. This study focused on a comparison of two energy dissipators- a) buckling restrained bracing (BRB) and b) fluid viscous damper (FVD) used in an RCC structure following pushover analysis to produce a pushover curve and evaluate structural performance. Four Ground floor + 14 (G + 14) storey RCC structures were created according to Indian Standard (IS) provisions in Extended Three-Dimensional Analysis of Building System (ETABS) software and applied BRB and FVD separately in diagonal and inverted V shapes. To compare structural responses with BRB and FVD independently, the results of the diagonal and inverted V systems have been explored. All the data were acquired by utilizing response spectrum sources developed under IS 1893:2016 following ASCE 41–13 NSP graphical display for static pushover curve in ETABS. It has been determined that the sample BRB has performed more admirably than FVD in both circumstances while using a diagonal and inverted V bracing system. But in large displacement FVD tends to increase performance. BRB is stiffer than FVD, allowing it to be used to raise the structure's stiffness as needed. It is essential to consider the seismic weight of BRB and FVD while designing a new building or retrofitting and restoring a structure.

Development of integrated semi-active adaptive vibration control system for bridges subjected to traffic loads

Nowadays, the fluid viscous damper is the most conventional energy dissipation system implemented in bridge structures to control the vibrations due to traffic loads. However, to effectively protect the bridge against frequent and severer vibrations, it is required to adapt the function of the damper according to the variable traffic loads. In this research, an Integrated Semi-Active Adaptive Vibration Control System is developed for the bridge structures. This control system consists of a Semi-Active Bypass Fluid Damper (SABFD), a programmable logic controller (PLC), pressure transducers, and displacement sensors. Semi-Active Bypass Fluid Damper is a hydraulic cylinder with a pair of external bypass pipes with motorized electric flow control valves which are installed in the middle of pipes to control the flow rate of the fluid. A programmable logic controller (PLC) is implemented to manage the operation of motorized valves according to the movement of the bridge.Therefore, the integrated control system is able to function as a real-time controller during its operation. To develop the control system, the performance of the SABFD device has been assessed through analytical model of the various control valve positions. Then, according to the structure response, a fuzzy control algorithm has been adapted in the PLC controller.Afterward, the prototypes of the SABFD and the PLC controller have been fabricated and a series of cyclic load tests have been conducted by using a dynamic actuator. The outcomes of the numerical analysis and results of the experimental tests revealed that the developed device is capable of generating a wide range of forces during device operation. The developed fuzzy control algorithm is then implemented to the finite element model of the bridge equipped with SABFD, and the results proved that the real-time control system effectively limits the bridge displacements according to the pre-defined fuzzy control rules.