• Geomechanics and Engineering
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• v.7 no.1
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• pp.87-103
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• 2014

This study investigated the effect of soil-structure interaction (SSI) on the response of base-isolated buildings. Seismic isolation can significantly reduce the induced seismic loads on a relatively stiff building by introducing flexibility at its base and avoiding resonance with the predominant frequencies of common earthquakes. To provide a better understanding of the movement behavior of multi-story structures during earthquakes, this study analyzed the dynamic behavior of multi-story structures with high damping rubber bearing (HDRB) behavior base isolation systems that were built on soft soil. Various models were developed, both with and without consideration of SSI. Both the superstructure and soil were modeled linearly, but HDRB was modeled non-linearly. The behavior of the specified models under dynamic loads was analyzed using SAP2000 computer software. Erzincan, Marmara and Duzce Earthquakes were chosen as the ground motions. Following the analysis, the displacements, base shear forces, top story accelerations, base level accelerations, periods and maximum internal forces were compared in isolated and fixed-base structures with and without SSI. The results indicate that soil-structure interaction is an important factor (in terms of earthquakes) to consider in the selection of an appropriate isolator for base-isolated structures on soft soils.

• Structural Engineering and Mechanics
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• v.34 no.1
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• pp.61-84
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• 2010

Presented in this paper is the behaviour of asymmetric building isolated by the double variable frequency pendulum isolator (DVFPI). The DVFPI is an adoption of single variable frequency pendulum isolator (VFPI). The geometry and coefficient of friction of top and bottom sliding surfaces can be unequal. The governing equations of motion of the building-isolation system are derived and solved in incremental form. The analysis duly considers the interaction of frictional forces in the two principal directions developed at each sliding surface of the DVFPI. In order to investigate the behaviour of the base isolation using the DVFPI, the coupled lateral-torsional response is obtained under different parametric variations for a set of six far-fault earthquake ground motions and criterion to optimize its performance is proposed. Further, influences of the initial time period, coefficient of friction and frequency variation factors at the two sliding surfaces are investigated. The numerical results of the extensive parametric study help in understanding the torsional behaviour of the structure isolated with the double sliding surfaces as in the DVFPI. It is found that the performance of the DVFPI can be optimized by designing the top sliding surface initially softer and smoother relative to the bottom one.

• International Journal of High-Rise Buildings
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• v.10 no.3
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• pp.219-227
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• 2021

This building is a forty-eight story, 170 meters high multiple dwelling house with Dual Frame System (DFS), a coupled vibration system connecting two independent structures with hydraulic dampers. Generation of large deformation between two structures during earthquakes contributes to make the hydraulic dampers effective. To improve the aseismic performance more, this building adopts DFS hybrid system that consists of DFS and base isolation system. About typical floors, columns and beams are constructed with LRV precast concrete method that shorten the construction period greatly by integrating column-beam joints in column members.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.2
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• pp.131-138
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• 2013

The high damping rubber bearings contributed to reduce a seismic force transmitted to upper structures, the material properties of rubber changes with time and the rubber with age-related degradation can affect the seismic response of structures and equipments. Therefore the seismic response of structure considering age-related degradation of isolators should be evaluated. In this paper, the stiffness and damping for isolators were defined using the aging data proposed by other researchers. The reactor containment building and the auxiliary building were selected to conduct the nonlinear analysis and the natural frequency, maximum responses, floor response spectrum(FRS) were evaluated with time using the four earthquakes with different frequency contents. According to the analysis results, the seismic responses are increased by the age-related degradation of isolators and the detail inspections should be conducted up to 20 years because it was presented that the change of FRS was high during this period.

• Earthquakes and Structures
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• v.18 no.3
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• pp.275-284
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• 2020

The scope of this study is the comparison between experimental results of tests performed on a base isolated building using helical wire rope isolators (WRs), and results of Nonlinear Response History Analyses (NRHAs) performed using SAP 2000, a commercial software for structural analysis. In the first stage of this research, WRs have been tested under shear deformation beyond their linear range of deformation, and analytical models have been derived to describe the nonlinear response of the bearings under different directions of loading. On the following stage, shaking table tests have been carried out on a 1/3 scale steel model isolated at the base by means of curved surface sliders (CSS) and WRs. The response of the structure under ground motion excitation has been compared to that obtained using numerical analyses in SAP 2000. The feasibility of modelling the nonlinear behavior of the tested isolation layer using multilinear link elements embedded in SAP 2000 is discussed in this paper, together with the advantages of using WRs as supplemental devices for CSSs base isolated structures.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.6 s.52
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• pp.67-77
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• 2006

Seismic activity of Korea is not so high as that of Japan or California and most of the structures were designed without considering the influence of earthquakes until the first seismic design code was enforced in 1988. Therefore, it was very hard to find seismically isolated structures in Korea until 1980's. Korean engineers assumed that the seismic isolation or vibration control would be useful only in a high seismicity region while such technologies can be quite useful in a low seismicity region for the efficient reduction of earthquake damages. Recently, Korean engineers began to have interest in the seismic isolation or vibration control and applied it to some important structures such as LNG storage tanks, many bridges and several buildings. However, design codes are not defining such useful advanced technologies for the design of building structures and several projects employing seismic isolation or vibration control in the design of structures had difficulties in obtaining construction permit from the local government. Therefore, it is an urgent requirement to introduce these advanced technologies in the seismic design code.

• Structural Engineering and Mechanics
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• v.48 no.1
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• pp.1-16
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• 2013

The seismic response of RC space frame structures with isolated footing resting on a shallow soil stratum on rock is presented in this paper. Homogeneous soil stratum of different stiffness in the very soft to stiff range is considered. Soil, footing and super structure are considered to be the parts of an integral system. A finite element model of the integrated system is developed and subjected to scaled acceleration time histories recorded during two different real earthquakes. Dynamic analysis is performed using mode superposition method of transient analysis. A parametric study is conducted to investigate the effect of flexibility of soil in the dynamic behaviour of low-rise building frames. The time histories and Fourier spectra of roof displacement, base shear and structural response quantities of the space frame on compliant base are presented and compared with the fixed base condition. Results indicate that the incorporation of soil flexibility is required for the realistic estimate of structural seismic response especially for single storey structures resting on very soft soil.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.487-494
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• 2006

The ultimate capacities of a rubber bearing are defined by compressive stress, shear strain, and stabilized roster ing force. The experiments were conducted with parameters of shesr elasticity(G) and first shape factor(S1), second shape factor(S2) for rubber bearing. Considering with test results, the ultimate capacities were verified, and furthermore the influence of those parameters were clarified. Using test results stable deformation of rubber bearings for designing was proposed.

• Earthquakes and Structures
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• v.17 no.2
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• pp.191-204
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• 2019

Near-field earthquake records including long-period high-amplitude velocity pulses can cause large isolation system displacements leading to buckling or rupture of isolators. In such cases, providing supplemental damping in the isolation system has been proposed as a solution. However, it is known that linear viscous dampers can reduce base displacements in case of near-field earthquakes but at the potential expense of increased superstructure response in case of far-field earthquakes. But can non-linear dampers with different levels of non-linearity offer a superior seismic performance? In order to answer this question, the effectiveness of non-linear viscous dampers in reducing isolator displacements and its effects on the superstructure response are investigated. A comparison with linear viscous dampers via time history analysis is done using a base-isolated benchmark building model under historical near-field and far-field earthquake records for a wide range of different levels of non-linearity and supplemental damping. The results show that the non-linearity level and the amount of supplemental damping play important roles in reducing base displacements effectively. Although use of non-linear supplemental dampers may cause superstructure response amplification in case of far-field earthquakes, this negative effect may be avoided or even reduced by using appropriate combinations of non-linearity level and supplemental damping.

• Journal of the Earthquake Engineering Society of Korea
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• v.17 no.2
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• pp.61-70
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• 2013

An application of the EQS (Eradi Quake System) bearings to a short period building structure and the structure earthquake responses according to the design parameters of the EQS are studied by the ICT Center case study. The features of the EQS application to seismic isolated building structures are investigated, and the design procedure to determine the yield load and the secondary stiffness of the EQS is also studied. A computational analysis is performed to confirm the applicability of the EQS to the building structure and the earthquake responses according to the design parameters. The ICT Center in Indonesia is adopted as an application case of the EQS. The application of the EQS is found to extend the fundamental period of the ICT Center. Three types of EQS with different yield loads and secondary stiffness are designed and applied in the earthquake response analyses. The analysis results show the response of the structure with respect to the design parameters and which type of EQS is suitable for the ICT Center.