Liquid Damper Research Articles

Upgrading the Seismic Capacity of Pile-Supported Wharfs Using Semi-Active Liquid Column Gas Damper

One of the most important structures in the ports is the wharf. The most common one is the pile-supported wharf. This type of wharf is consisted of a number of piles and one deck which placed on the piles. In addition to the conventional loads that this structure should withstand, in seismic areas, pile-supported wharfs should have the necessary capacity and strength against seismic excitations. There are some approaches to increase the seismic capacity of the berth. One of these methods is to control the vibrations of the pile-supported wharf against earthquake loads using a damper. In this research, for the first time, a new semi-active damper called the semi active liquid column gas damper (SALCGD), was used to reduce the response of pile supported wharf under seismic loads. In the first step by applying different records of the earthquake, the most important parameter of this damper - the optimal opening ratio of the horizontal column- was obtained for this particular structure. In the following, the performances of this damper and its comparison with the tuned liquid column gas damper (TLCGD) were discussed. This study showed that the use of this semi-active damper (SALCGD) reduces the displacement of the pile-supported wharf by 35% and reduces the acceleration of the structure by 50% on average. In contrast, the passive damper (TLCGD) reduces the displacement of about 20 percent and the acceleration of about 30 percent. Therefore, it was observed that the semi-activation of the damper (SALCGD) had a significant improvement in its performance in controlling the vibrations of pile-supported wharf.

Study on Seismic Performance of Long-Span Railway Continuous Girder Bridges in High Seismic Intensity Region

In order to study the seismic response characteristics of long-span railway continuous girder bridges, located in the high seismic intensity regions. Take reasonable measures, to solve the seismic problem of fixed piers. This paper introducing a long-span railway continuous girder bridge as a research background, establishes a finite element model, nonlinear seismic response analysis of the whole bridge was carried, using the ductile seismic design method and the seismic isolation method. The parameters of the liquid viscous damper, and its influence on the damping effect are discussed. The results show that when using the ductility seismic design method, the structure relies on the plastic hinge hysteresis mechanism to dissipate the seismic energy, which may causes the large damage of the fixed pier. After damping design, the seismic design difficulty has been reduced. But to further solve the seismic problem, it is recommended that other seismic isolation devices be used simultaneously.

Features for formation of structure and properties of highstrength steel 30KhGSN2A in production of liquid dampers

The causes of premature failure of liquid dampers made of high-strength steel 30KhGSN2A and used on vehicles are studied. Recommendations are developed on adjusting the modes of fi nishing heat treatment of barrels and surface treatment of rods, providing improved microstructure and the required level of steel properties, as well as reliable operation of the dampers.

Numerical and experimental investigations of the sloshing modal properties of sloped-bottom tuned liquid dampers for structural vibration control

Tuned liquid dampers (TLDs) utilize the liquid sloshing to damp vibrations of civil and mechanical structures. Rectangular tank with flat-bottom has been widely used for passive structural control. A recent experimental study, on the other hand, indicates that a TLD with sloped bottom achieves better performance than its flat-bottom counterpart, considering the improved vibration mitigation and reduced liquid mass. This work investigates the sloshing modal properties (sloshing frequencies and sloshing mode shapes) of sloped-bottom TLD using finite difference method, which is validated by full-scale tests. It is observed that the sloshing mode shapes are quite different comparing the shallow-water sloped-bottom TLD with the deep-water one. To further reveal the influence of damper geometries on the sloshing modal properties of the sloped-bottom TLD, three different geometrical parameters have been considered for parametric study, e.g. the mean water level of the liquid, the slope angle, and the ratio between the horizontal projection length of the slope and the total bottom length. It is found that the sloshing eigenfrequencies increase as the mean water level increases, as the slope angle decreases and as the length ratio increases. The eigenfrequencies vary with damper geometries in a nonlinear manner, and the results from flat-bottom TLD always act as upper limit of those from sloped-bottom TLD. The developed numerical model in the present study can be used for tuning and preliminary design of structural-mounted sloped-bottom TLDs.

Parameter Optimization and Control Characteristics Analysis of TLMD System Based on Phase Deviation

Combined with the advantages and disadvantages of tuned liquid damper (TLD) and tuned mass damper (TMD), a double tuned liquid mass damper (TLMD) is proposed by replacing the rigid connection of TLD with the spring structure. The motion equation of a single-degree-of-freedom structure with a TLMD attached at its top is found under harmonic excitation. Comparing the energy consumption and amplitude of primary structure with equal mass ratio TMD, it is found that the energy dissipation performance of TLMD is better in the effective phase region. The interaction process between TLMD and structure is analyzed, and the formula of phase deviation between the relative velocity of tank and the displacement of primary structure is deduced. By analyzing the influence of mass ratio, frequency ratio, damping ratio and water depth ratio on the damping effect, the results show that the frequency ratio and liquid depth ratio have great influence on the size and location of deep resonance peak, and the mass ratio and damping ratio have great influence on the width of the effective frequency band. The formula of equivalent damping ratio is proposed based on the principle of energy and it is found that the equivalent damping ratio is related to the phase deviation and change with the frequency ratio of the external excitation.

Application of the DAE approach to the nonlinear sloshing problem

The nonlinear sloshing problem is an important issue for design of liquid storage tanks, liquid cargo transportations, tuned liquid dampers and so on. This paper is concerned with development of a novel approach for the nonlinear sloshing problem based on the Hamiltonian mechanics. In particular, this study is aimed at developing the method available to analyze the nonlinear liquid surface behavior like a traveling wave observed in the small liquid depth. In the present formulation, the fluid is assumed to be inviscid incompressible and irrotational flow. Then, the liquid surface motion is described by nonlinear multimodal models. However, since the sloshing problem based on such assumptions yields an irregular Lagrangian, it makes formulation difficult in a straightforward way. Therefore, the present approach employs the constrained Hamiltonian mechanics with the Lagrange’s method of undetermined multipliers to derive equations of motion. The resulting system is comprised of differential equations and algebraic equations, referred to as differential algebraic equations (DAEs). In addition, the present method takes full account of the nonlinear mode-to-mode interactions without reduction methods focusing on the predominant sloshing modes. However, the multimodal models without such reduction methods suffer from severe numerical stiff problem. Therefore, the numerical integration techniques based on implicit schemes (DAE solver) are incorporated as remedies for the stiff problem. Specifically, discrete forms of the equations of motions are derived by employing the Galerkin method and a discrete derivative. The proposed approach is validated by comparisons with an existing model and an experiment in time domain analysis.

Numerical Analysis of the Dynamic Responses of Multistory Structures Equipped with Tuned Liquid Dampers Considering Fluid-Structure Interactions

Aims:The paper analyzes the effectiveness of tuned liquid damper in controlling the vibration of high rise building. The new contribution is considering the fluid-structure interaction of a water tank as a Tuned Liquid Dampers (TLD).Background:Currently, buildings are being built higher and higher, which requires TLDs to be larger as well. Therefore, the fluid pressure acting on the tank wall is more significant. In previous studies of liquid sloshing in TLDs, researchers simply ignored the effect of liquid pressure acting on the tank walls by making the assumption that the tanks are rigid. Currently, the failure of a tank because of FSI occurs regularly, so this phenomenon cannot be ignored when designing the tanks in general and TLDs in particular.Objective:To investigate the thickness of the tank wall affect to the TLD mechanism.Method:Numerical method was used for this research.Results:A TLD could be easy to design; however one could not bypass the fluid-structure interaction by assuming the tank wall is rigid.Conclusion:This kind of damper is very good to mitigate the dynamic response of structrure.

Analytical Solution of Sloshing in a Cylindrical Tank with an Elastic Cover

Coupled fluid-structure is significant in many aspects of engineering applications such as aerospace fuel tanks, the seismic safety of storage tanks and tuned liquid dampers. Numerical investigation of the effects of thin plate cover over a cylindrical rigid fuel tank filled by an inviscid, irrotational, and incompressible fluid is investigated. Governing equations of fluid motion coupled by plate vibration are solved analytically. A parameter study on the natural frequency of coupled fluid-structure interaction is performed. The results show the non-dimensional natural frequency of coupled fluid-structure is a function of mass ratio, plate elasticity number and aspect ratio. This function is derived numerically for high aspect ratios which in companion with a semi-analytical could be used in the engineering design of liquid tanks with a cover plate.

Shaking Table Test on Different Positions of Multiple Tuned Liquid Damper

Earthquake can cause many problems to the structures, which lead to buildings collapse and may takes humans life. It is a nature’s hazard that cannot be stop. One of the effort is by introducing the damping system to the buildings where the energy of the system is slowly reduced until the vibration of the system is totally eliminated and the system is brought to rest. Several techniques are available nowadays, however passive control system has advantage in term of cost compare to other systems. Multiple Tuned Liquid Damper (MTLD) is a passive system that traditionally made of several rigid tanks filled with water, usually placed on top of a building. The energy will dissipates through the sloshing and wave-breaking of the liquid once the earthquake strike the buildings. Shaking table tests are carried out on a two-bay, two-story steel frame with water tanks for different location. In this test, the displacement and acceleration for top and base are studied.

Application of tuned liquid column ball damper (TLCBD) for improved vibration control performance of multi-storey structure.

Tuned liquid column ball damper (TLCBD) is a passive control device used for controlling the building vibrations induced from wind or earthquakes. TLCBD is a modified form of conventional tuned liquid column damper (TLCD). This paper studies the effect of TLCBD on the four-storey steel frame structure. The performance of the TLCBD is also compared with conventional TLCD. The analytical model of both TLCD and TLCBD is presented here. The effectiveness of these analytical models is examined experimentally by series of shaking table tests under different excitation levels including harmonic loadings and seismic excitations. In TLCBD, the vibration is reduced significantly as compared to TLCD by using steel ball as a moving orifice. The difference in diameter of steel ball and tube, containing the liquid column, acts as an orifice which moves with the movement of the ball. This moving orifice phenomenon enhanced the vibration reduction effect by resisting the water motion in the TLCBD. Root mean square (RMS) and peak values of acceleration were calculated for each loading and each storey of uncontrolled and controlled structures. Comparison of the time histories of controlled and uncontrolled structures for different loadings is also reported. Results indicate that the TLCBD is more effective in the earthquake scenarios as compared to the harmonic excitations. The TLCBD controls the vibration of the primary structure significantly in vibration reduction.

Structural control of a fixed offshore structure using a new developed tuned liquid column ball gas damper (TLCBGD)

Structural control of a system can be achieved by employing different control methods. The effectiveness of a control technique straightly depends on the performance of the control device. Among control devices, the tuned liquid column gas damper (TLCGD) has shown high vibration control capabilities. In this study, a newly developed damping system as a tuned liquid column ball gas damper (TLCBGD) system is introduced. The developed system is a combined version of a tuned liquid column ball damper (TLCBD) and a TLCGD system. The new damper is utilized on an offshore jacket platform and its qualification is studied under both regular and irregular wave incidences. The efficiency of the TLCBGD system is investigated numerically by implementing ball-tube ratio and gas pressure parameters. The effects of the ball-tube ratios and the gas pressure values on the vibration suppression capacity of the system are assessed through a parametric study. In comparison to a passive TLCGD system, the results revealed that the utilizing a TLCBGD system in the jacket platform improves the structural vibration suppression capability.

Coupled shallow-water fluid sloshing in an upright annular vessel

The coupled motion of shallow-water sloshing in a horizontally translating upright annular vessel is considered. The vessel’s motion is restricted to a single space dimension, such as for Tuned Liquid Damper systems. For particular parameters, the system is shown to support an internal 1 : 1 resonance, where the frequency of coupled sloshing mode which generates the vessel’s motion is equal to the frequency of a sloshing mode which occurs in a static vessel. Using a Lagrangian Particle Path formation, the fully nonlinear motion of the system is simulated using an efficient numerical symplectic integration scheme. The scheme is based on the implicit-midpoint rule which conserves energy and preserves the energy partition between the fluid and the vessel over many time-steps. Linear and nonlinear results are presented, including those showing the system transitioning to higher-frequency eigenmodes as the fluid depth is reduced.

A tuned liquid inerter system for vibration control

This study proposes a novel tuned liquid inerter system (TLIS) that employs a tuned liquid element and an inerter-based subsystem, including damping, stiffness, and inerter elements, to completely utilize their synergy benefits. The stochastic analyses for both damped and undamped structure-TLIS systems are conducted, and the analytical solution to the displacement response is derived for an undamped structure. Using the stochastic response results, the vibration control effect of the proposed TLIS is characterized through an extensive analysis in comparison with classic tuned liquid dampers. A parametric analysis is then performed to investigate the response variation pattern of the structure-TLIS with respect to the changes in TLIS parameters. Inspired by the parametric analysis, an optimal design framework for the most economical condition is developed for the TLIS by simultaneously considering the structural performance and control force. In particular, for a TLIS in the presence of an existing tuned liquid element, the optimal damping and stiffness ratios of the inerter subsystem in the TLIS are derived in an analytical form as the functions of tuned liquid mass and inertance to ensure structural responses are minimized. Moreover, the corresponding design procedure and examples are provided to validate the effectiveness of the proposed TLIS and design methods. It is concluded that the employment of the inerter-based subsystem in the TLIS can substantially improve the structural performance and reduce the displacement response of the tuned liquid in comparison with the classic tuned liquid damper for a given liquid mass. The optimal design of the TLIS can satisfy the target structural performance demands despite optimizing control cost. Simultaneously, the function of the tuned liquid element is partly substituted by the added inerter element, which implicitly facilitates the minimization of the physical mass of the TLIS to achieve lightweight-based control.

Shaking table tests on a SDOF structure with cylindrical and rectangular TLDs having rotatable baffles

Control of vibrations against extraordinary excitations such as wind and earthquake is very important to the protection of life and financial concerns. One of the methods of structural control is to use Tuned Liquid Damper (TLD), however due to the nature of TLD only one sloshing frequency can be created when the water is sloshing. Among various ideas proposed to compensate this problem, by changing the angle of some rotatable baffles embedded inside a TLD, a frequency range is created such that these baffles are tuned manually at different frequencies. In this study, the effect of cross sectional shape of container with rotating baffles on seismic behavior of TLD is experimentally studied. For this purpose, rectangular and cylindrical containers are designed and used to suppress the vibrations of a Single Degree-Of-Freedom (SDOF) structure under harmonic and earthquake excitations considering three baffle angles. The results show that the rectangular-shaped damper reduces the structural response in all load cases more than the damper with a cylindrical shape, such that maximum differences of two dampers to reduce the structural displacement and structural acceleration are 5.5% and 3% respectively, when compared to the cases where no baffles are employed.

Seismic Control of Structures Using Sloped Bottom Tuned Liquid Damper

Tuned liquid damper (TLD) as an economical passive damper has gained importance because of its efficiency in suppressing the undesirable motion of a structure due to devastating earthquakes when it is rigidly attached to the structure. This phenomenon has been studied previously, but mostly limited to rectangular- or cylindrical-shaped TLD. The present study is aimed at determining the potential of the sloped bottom tuned liquid damper to suppress the unwanted vibration of the structure subjected to earthquake ground motion. Three different earthquake ground motions characterized by low-, intermediate- and high-frequency contents are selected for the dynamic analysis of the TLD–structure coupled system. A parametric study on the sloped bottom TLD and its interaction with the sustaining structural system is conducted. The structural equations, which are coupled with fluid equations, are solved by the Newmark-[Formula: see text] method with average acceleration, while the fluid equations are solved using velocity potential-based finite element method. The liquid domain in the TLD is comprised of a combination of three-node triangular and four-node quadrilateral elements. The result shows the reduction in structure response is significant with less amount of water in sloped bottom TLD rather than rectangular TLD.

Modified Tuned Liquid Dampers for Seismic Protection of Buildings Considering Soil–Structure Interaction Effects

Considering the effect of soil–structure interaction in dynamic analysis of structures can change their responses. It is generally assumed that the structure is located on a rigid foundation and the flexibility effect of the soil is not considered. Researches on the soil–structure interaction show that the dynamic response of the structures located on a soft and flexible soil is completely different from the dynamic response of the same structure located on a stiff soil. In this paper, the effect of the soil–structure interaction on the response of a single-degree-of-freedom system (Nagasaki airport tower) that is controlled by a modified tuned liquid damper is investigated. The soil effect is modeled using an approximate cone method based on the semi-infinite boundary conditions. First, the governing equations for describing the fluid sloshing obtained with shallow water wave theory are solved by Lax’s finite-difference scheme. Then, the dynamic equilibrium equations for a structure controlled with a modified tuned liquid damper are obtained by considering the effect of soil–structure interaction using Lagrange’s method. These equations are solved numerically by Newmark’s method. The controlled structural responses are calculated in different time steps and compared with the responses of the uncontrolled structure. Results show that the seismic design of the modified tuned liquid damper system can be more effective to reduce the structural responses. Also, this system can reduce efficiently the maximum responses of the structures considering soil–structure interaction effect during a near-fault earthquake.

Application Research of Liquid Viscous Damper in Controllable Structure

The controllable structure assembling the additional liquid viscous damper shows good structural characteristics through theoretical analysis and the comparison with model test. Liquid viscous dampers can significantly change the basic dynamic characteristics of the structure and exhibit certain regularity. According to the research, the ability of the structure assembling damper to adjust itself is greater than the effect of same structure adding weight, which indicates that the liquid viscous damper plays a prominent role in controlling the structural response.

Structural control of a grandstand using a semi‐active pressurized tuned liquid column damper considering effects of passive crowds

Structural control of a grandstand using a semi‐active pressurized tuned liquid column damper considering effects of passive crowds

Investigating the effect of far and near field to fault on seismic behavior of dual frames with convergent bracing equipped with viscose damper

Abstract In this study, non-linear behavior of steel frames with dual lateral loader system with convergent crossing and chevron bracing equipped with linear and non-linear liquid viscose dampers i...

Experimental evaluation of tuned liquid column damper and tuned mass damper in a space structure model

Vibrations in building structure due to external force can be minimalized by absorber installation. One technique in that regard is through the dynamic absorber. Previous reports have developed double dynamic vibration absorber namely Tuned Liquid Column Damper (TLCD) and spring-mass system. However, the conduct has been applied to reduce vibrations occurred on solely one-sided movement. This study investigated the double dynamics absorber utilization of Tuned Liquid Column Damper (TLCD) and spring-mass system that was designed to be capable of vibration reduction caused by interfering forces on two-sided structures hence the implementation can be more applicative.