• Earthquakes and Structures
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• v.15 no.2
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• pp.133-144
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• 2018

To study the effectiveness of sliding isolation in a CRLSS (concrete rectangular liquid-storage structure) and develop a reasonable limiting-device method, dynamic responses of non-isolation, sliding isolation with spring limiting-devices and sliding isolation with steel bar limiting-devices are comparatively studied by shaking table test. The seismic response reduction advantage of sliding isolation for concrete liquid-storage structures is discussed, and the effect of the limiting-device type on system dynamic responses is analyzed. The results show that the dynamic responses of sliding isolation CRLSS with steel bar-limiting devices are significantly smaller than that of sliding isolation CRLSS with spring-limiting devices. The structure acceleration and liquid sloshing wave height are greatly influenced by spring-limiting devices. The acceleration of the structure in this case is close to or greater than that of a non-isolated structure. Liquid sloshing shows stronger nonlinear characteristics. On the other hand, sliding isolation with steel bar-limiting devices has a good control effect on the structural dynamic response and the liquid sloshing height simultaneously. Thus, a limiting device is an important factor affecting the seismic response reduction effect of sliding isolation. To take full advantage of sliding isolation in a concrete liquid-storage structure, a reasonable design of the limiting device is particularly important.

• Earthquakes and Structures
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• v.25 no.5
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• pp.343-358
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• 2023

The superelastic viscous damper (SVD) is a hybrid passive control device comprising a viscoelastic damper and shape memory alloy (SMA) cables connected in series. The SVD is an innovative damper through which a large amount of seismic energy can dissipate. The current study assessed the seismic collapse induced by steel moment-resisting frames (SMRFs) equipped with SVDs and compared them with the performance of special MRFs and buckling restrained brace frames (BRBFs). For this purpose, nonlinear dynamic and incremental dynamic analysis (IDA) were conducted in OpenSees software. Both 5- and 9-story special MRFs, BRBFs, and MRFs equipped with the SVDs were examined. The results indicated that the annual exceedance rate for maximum residual drifts of 0.2% and 0.5% for the BRBFs and MRFs with SVDs, respectively, were considerably less than for SMRFs with reduced-beam section (RBS) connections and that the seismic performances of these structures were enhanced with the use of the BRB and SVD. The probability of collapse due to residual drift in the SVD, BRB, and RBS frames in the 9-story structure was 1.45, 1.75, and 1.05 times greater than for the 5-story frame.

• Structural Engineering and Mechanics
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• v.36 no.5
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• pp.561-573
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• 2010

The potential of the liquid column vibration absorber (LCVA) as a seismic vibration control device for structures has been explored in this paper. In this work, the structure has been modeled as a linear, viscously damped single-degree-of-freedom (SDOF) system. The governing differential equations of motion for the damper liquid and for the coupled structure-LCVA system have been derived from dynamic equilibrium. The nonlinear orifice damping in the LCVA has been linearized by a stochastic equivalent linearization technique. A transfer function formulation for the structure-LCVA system has been presented. The design parameters of the LCVA have been identified and by applying the transfer function formulation the optimum combination of these parameters has been determined to obtain the most efficient control performance of the LCVA in terms of the reduction in the root-mean-square (r.m.s.) displacement response of the structure. The study has been carried out for an example structure subjected to base input characterized by a white noise power spectral density function (PSDF). The sensitivity of the performance of the LCVA to the coefficient of head loss and to the tuning ratio have also been examined and compared with that of the liquid column damper (LCD). Finally, a simulation study has been carried out with a recorded accelerogram, to demonstrate the effectiveness of the LCVA.

• Earthquakes and Structures
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• v.25 no.6
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• pp.455-467
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• 2023

This study focuses on demonstrating the effectiveness of vibration control of tuned rotary mass damper (TRMD) for reducing the bidirectional and torsional response of the irregular asymmetric structure with voided slabs under earthquake excitations. The TRMD arranged in plane of one-story eccentric structure is proposed as a distributed tuned rotary mass damper (DTRMD) system. Lagrange's equation is used to derive the equations of motion of the controlled system. The optimum position and number of TRMD are numerically investigated under harmonic excitation and the control effects of different distributions are discussed. Furthermore, a shaking table test is conducted under different excitation cases, including free vibration, forced vibration and seismic wave to investigate the absorption performance of the device. The numerical simulations of different distributions of the TRMDs show that the DTRMDs are more effective in reduction of the displacement response of the asymmetric structure under the same mass ratio, even when the degree of eccentricity becomes large. However, with small degree of eccentricity, the unreasonable asymmetrical arrangement may cause the increase of the peak value of the rotational angular displacement. Finally, the experimental investigations exhibit similar results of translational displacement of the structure. It is concluded that the vibration of the irregular asymmetric structure can be controlled more economically and effectively by reducing the mass ratio through reducing the quantity of TRMDs at the high stiffness end.

• Journal of Korean Association for Spatial Structures
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• v.13 no.3
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• pp.91-98
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• 2013

A multi-input single-output (MISO) semi-active control systems were studied by many researchers. For more improved vibration control performance, a structure requires more than one control device. In this paper, multi-input multi-output (MIMO) semi-active fuzzy controller has been proposed for vibration control of seismically excited small-scale buildings. The MIMO fuzzy controller was optimized by multi-objective genetic algorithm. For numerical simulation, five-story example building structure is used and two MR dampers are employed. For comparison purpose, a clipped-optimal control strategy based on acceleration feedback is employed for controlling MR dampers to reduce structural responses due to seismic loads. Numerical simulation results show that the MIMO fuzzy control algorithm can provide superior control performance to the clipped-optimal control algorithm.

• Journal of Korean Society of Steel Construction
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• v.24 no.2
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• pp.149-161
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• 2012

The use of seismic energy-dissipative devices for passive control is increasing exponentially in the recent years for both new and existing buildings. Use of these devices started in and has been somewhat limited to developed countries. One of the current challenges is to promote the use of seismic dampers in earthquake-prone developing countries by lowering the cost of the devices. This paper proposed a new type of seismic damper based on yielding of a cantilever type metallic element for seismic retrofit of existing and new building structures. The hysteretic behavior and energy dissipation capacity of the proposed damper was investigated using component tests under cyclic loads. The experimental results indicated that the damping device had stable restoring force characteristics and a high energy dissipation capacity. Based on these results, a simple hysteretic model for predicting the load-displacement curve of the seismic damper was proposed.

• Structural Monitoring and Maintenance
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• v.5 no.2
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• pp.205-229
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• 2018

Energy induced by minor earthquake and micro vibration cannot be dissipated by traditional buckling-restrained braces (BRBs). To solve this problem, a new type of hybrid passive control device, named as VE-BRB, which is configured by a BRB with high-damping viscoelastic (VE) layers, is developed and studied. Theoretical analysis, performance tests, numerical simulation and case analysis are conducted to study the seismic behavior of VE-BRBs. The results indicate that the combination of hysteretic and damping devices lead to a multi-phased nature and good performance. VE-BRB's working state can be divided into three phases: before yielding of the steel core, VE layers provide sufficient damping ratio to mitigate minor vibrations; after yielding of the steel core, the steel's hysteretic deformations provide supplemental dissipative capacity for structures; after rupture of the steel core, VE layers are still able to work normally and provide multiple security assurance for structures. The simulation results agreed well with the experimental results, validating the finite element analysis method, constitutive models and the identified parameters. The comparison of the time history analysis on a 6-story frame with VE-BRBs and BRBs verified the advantages of VE-BRB for seismic protection of structures compared with traditional BRB. In general, VE-BRB had the potential to provide better control effect on structural displacement and shear in all stages than BRB as expected.

• Journal of the Earthquake Engineering Society of Korea
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• v.24 no.3
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• pp.149-156
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• 2020

The vibration control device such as the damper can be used to reinforce the seismic performance of structures. The damper is activated by the deformation of structures during earthquake; however, the deformation of structures is extremely small, causing difficulty in using the damper. Therefore, there is a need for a method capable of amplifying small deformities and transmitting them to the damper. The purpose of this paper is to develop and evaluate a displacement amplification seismic system using cable-pulley. The appropriate cable was selected through a cable tensile performance test and the results of the frame experiment were compared with theoretical displacement amplification ratio values. As a result, it may be said that the proposed system using cable-pulley is useful for displacement amplification.

• Earthquakes and Structures
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• v.23 no.5
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• pp.419-430
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• 2022

The metallic energy dissipation device (EDD) has been widely accepted as a useful tool for passive control of buildings against earthquakes. The distribution of metallic EDDs in a multi-story building may have significant influence on its seismic performance, which can be greatly enhanced if the distribution scheme is properly designed. This paper addresses the optimal distribution problem in the aim of achieving a desired level of performance using the minimum number of metallic EDDs. Five local search heuristic algorithms are proposed to solve the problem. Four base structures are presented as numerical examples to verify the proposed algorithms. It is indicated that the performance of different algorithms may vary when applied in different situations. Based on the results of the numerical verification, the recommended guidelines are finally proposed for choosing the appropriate algorithm in different occasions.

• Journal of the Korean Society of Safety
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• v.29 no.2
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• pp.31-37
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• 2014

For the vibration control of residential buildings, a multiple type slim damper system is developed and dynamic performance test is performed in this study. In conventional damping systems, larger installation space is required in order to achieve acceptable seismic performance, and as a result, it is difficult to determine efficient damping capacity of the device. The proposed damping device is composed of several small slim type dampers and linkage units. It can control damping capacity easily by changing the number of the small damper. To evaluate the proposed damping device, three slim type dampers (single-type, triple-type and penta-type) are designed and manufactured in real scale. Dynamic loading tests are performed by using the three manufactured dampers. From the tests, it is shown that damping coefficient is proportional to the number of the damper combined. Thus, test results validates the practicality of the proposed slim type dampers. applying nonlinear curve fitting technique, numerical model of the dampers are developed and presented.