• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.601-611
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• 2016

The research, development and use of seismic isolation systems have been increasing with the gradual development of structure safety assurance methods for earthquakes. The High Damping Rubber Bearing (HDRB), one type of seismic isolation system, is a Laminated Rubber Bearing using special High Damping Rubber. However, as its damping function is slightly lower than that of the Lead Rubber Bearing, a similar seismic isolation system, its utilization has not been high. However, the HDRB has a superior damping force to the Natural Rubber Bearing, which has similar materials and shapes, and the existing Lead Rubber Bearing has a maleficence problem in that it contains lead. Thus, studies on HDRBs that do not use lead have increased. In this study, a test targeting the HDRB was done to examine its various dependence properties, such as its compressive stress, frequency and repeated loading. To evaluate the HDRB's seismic performance in response to several earthquake waves, the shaking table test was performed and the results analyzed. The test used the downscaled bridge model and the HDRB was divided into seismic and non-seismic isolation. Consequently, when the HDRB was applied, the damping effect was higher in the non-seismic case. However, its responses on weak foundations, such as in Mexico City, represented increased shapes. Thus, its seismic isolator.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2A
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• pp.121-129
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• 2010

In this paper, the characteristics of high damping rubber bearing were studied through various prototype test. The characteristics of HDRB were dependent on displacements, repeated cycles, frequencies, vertical pressure, temperature, the capability of shear deformation and the vertical stiffness. The prototype test showed that the displacement was the most governing factor influencing on characteristics of HDRB. The effective stiffness and equivalent damping of HDRB were decreased with displacement, and increased with frequency. The effective stiffness was decreased with high vertical pressure, while the equivalent damping was increased. In which, the equivalent damping was more dependent on the vertical pressure than the effective stiffness. According to the results of this study, more careful examination is required to design the effective stiffness and equivalent damping ratio considering the dependencies of design displacement and exciting velocity.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.1
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• pp.53-60
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• 2009

Isolated structures use devices such as high damping rubber bearings (HDRB) in order to dramatically reduce the seismic forces transmitted from the substructure to the superstructure. The laminated rubber bearing is the most important structural member of a seismic isolation system. The basic characteristics of rubber bearings have been confirmed through compression tests, compressive shearing tests and creep tests. This paper presents the results and analysis of a 1000hr, ongoing creep test conducted at 7.5MPa, 8.37MPa in our laboratory. The long-term behavior of bridge bearings, such as high-damping rubber bearings, will be discovered through a compression creep test subjected to actual environmental conditions. These tests indicated that the maximum creep deformation is about $0.3{\sim}1.92%$ of total rubber thickness.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.3
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• pp.11-20
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• 2008

In this paper, the characteristics of low hardness high damping rubber bearings(HDRB) were studied through various prototype tests. The low hardness HDRB were tested to evaluate vertical stiffness, shear stiffness, equivalent damping ratio, various dependencies of shear properties, ultimate shear properties and other factors. The prototype test was performed according to the specifications of ISO 22762-1, and evaluated according to the specifications of ISO 22762-3. The results of the prototype test showed that shear strain and temperature were the factors that most greatly influenced shear stiffness, and that compressive stress was the factor that most greatly influenced the equivalent damping ratio. The frequency dependence test of shear properties showed that two general tendencies of frequency dependence could be observed. At frequencies over 0.1Hz, the changes in shear properties were small. However, at frequencies under 0.1Hz, the changes in shear properties rapidly decreased. The creep test and the ultimate shear test were also performed, and both of them satisfied the requirements of ISO 22762-3.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.4
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• pp.73-86
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• 1998

The purpose of this paper is to evaluate the shear stiffness, hysteretic behavior, and ultimate behavior of HDRB(High Damping Rubber Bearing), which will be included in the seismic isolation design guideline as requirements. To do this, two 1/8 scaled HDRB are designed, fabricated, and tested to show the mechanical characteristics. The shear stiffness obtained from the proposed equation of the shear stiffness shows a good agreement with those of the experiments. For analysis of the hysteretic behavior of HDRB using the modified rate model, the parameter equations are obtained from the experiments. Using the obtained parameter equations for the modified rate model, the seismic response analyses are carried out for 1-D system. The results of analysis well follow the hysteretic behavior of HDRB obtained from the experiments. To evaluate the ultimate behavior of HDRB used in this paper, the analyses are carried out using the modified macro model, which can consider the large shear deflection. The critical shear strain(CSS) is defined to express the maximum allowable shear strain and vertical load. From the analyses, the CSS, showing the instability, decreases significantly as increased the vertical loads. The CSS is not appeared for the design vertical load in the used HDRB. In analysis using about 5 times of design vertical load, the HDRB start to show the instability transient and for about 7 times, the CSS is about 350%.

• Journal of the Regional Association of Architectural Institute of Korea
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• v.21 no.1
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• pp.185-192
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• 2019

Recently, the frequency and magnitude of earthquakes are increasing worldwide. In Korea, the Gyeongju earthquake (2016) and the Pohang earthquake (2017) caused structural damage to many buildings. Since Korea's seismic design standards were revised to three or more stories in 2005, five-story buildings built before the revision are not designed to be earthquake-resistant. In this situation, if strong earthquake occurs in Korea, there will be great damage. To prevent this, seismic retrofit of buildings should be necessary. The seismic retrofit of classical method is mainly used to reduce the displacement generated in the structure by strengthening stiffness and strength. However, since this method increases the base shear force of the structure, it is difficult to apply it to buildings which have weak foundation. Therefore, in this study, we propose the damper system that reduces the response displacement of buildings and suppresses the increase of base shear force by using high damping rubber and steel. And the seismic performance of the damper system is verified through the experiment and the seismic analysis of the structure.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.5 s.39
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• pp.65-77
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• 2004

In this study, the base isolation systems for equipment in the NPP are presented and the responses of each isolation system are investigated. As for the base isolation systems, a natural rubber bearing (NRB) and a high damping rubber bearing (HDRB) are selected. As input motions, artificial time histories enveloping the US NRC RG 1.60 spectrum and the probability-based scenario earthquake spectra developed for the Korean nuclear power plant site as well as a typical near-fault earthquake record are used. Uniaxial, biaxial, and triaxial excitations are conducted with PGAs of 0.1, 0.2 and 0.25g. The reduction of the seismic forces transmitted to the equipment models are determined for different isolation systems and input motions.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.10a
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• pp.216-217
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• 2010

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.04a
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• pp.419-425
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• 2001

The shear modulus of 3-bar lap rubber shear dynamic test specimen is investigated through incremented shear strain tests. The shear force-strain relation of rubber specimen is also calculated by ABAQUS using hyper-elastic material properties of high damping rubber. The analysis results are compatible with shear dynamic tests of 3-bar lap rubber specimen and 1/8 reduced-scale laminated rubber bearing

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.292-297
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• 2000

The seismic isolation technology has appeared to be increasingly necessary for highway bridges, LNG tank, nuclear power plant, and building structures in view of earthquake vibrations. Also high-technology industries require effective seismic protection. The Seismic Isolation Bearing - High Damping Rubber Bearing - system has been counted as the most effective way fur seismic isolation, which is now under development and widely used in industries. Here, the commercial FEM software for nonlinear analysis, MARC, has provided force-displacement curves on the rubber system. The analyses have been carried out about fourteen cases; 25%, 50%, 75%, 100%, 125% and 150% horizontal displacements with a different frequency - 0.01Hz and 0.50Hz - and 100% horizontal displacement with four different frequency - 0.01Hz, 0.16667Hz, 0.3333Hz and 0.50Hz. The unknown constants of the strain energy function of Ogden model have been obtained by a tension test and planar shear test.