• Journal of the Korean Geotechnical Society
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• v.19 no.4
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• pp.211-221
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• 2003

The response displacement method is the most frequently used method for seismic design of underground structures. This method is pseudo-static method, and the evaluations of velocity response spectrum of seismic base and response displacement of surrounding soil are the most important steps. In this study, the evaluation of velocity response spectrum of seismic base according to the Korean seismic design guide and the simple method of calculating the response displacement were studied. It was found that velocity response spectrum of seismic base can be estimated by directly integrating the ground-surface acceleration response spectrum of soil type S$_A$, and the evaluation of the response displacement using double cosine method assuming two layers of soil profile shows the advantages in the seismic design.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.1
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• pp.57-66
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• 2008

An experimental study was performed to evaluate seismic reduction performance and applicability of 3-dimensional floor isolation system to the main control room of nuclear power plant. A friction pendulum system(FPS) and air spring were designed and fabricated for 3-dimensional floor isolation system. Two kind of the partial experimental model of a main control room attached to the FPS and air spring were tested on the shaking table. The experimental model consisted of a control panel, a $2.5m{\times}2.5m$ access floor, four FPS and air springs. The artificial time histories based on the vertical and horizontal floor response spectrums(OBE, SSE) of the main control room were used as the earthquake input signals in the test. Compared to non-isolated system, the seismic response of experimental models using 3-dimensional floor isolation system were shown considerable seismic reduction performance.

• Land and Housing Review
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• v.2 no.3
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• pp.287-297
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• 2011

This paper presents the results of performance verification tests of the isolated flat plate apartment building with the laminated rubber bearings. The shaking table test is carried out in CABR(China Academy of Building Research) with two 1/10 scale isolation and non-isolation models under 4 excitation waves. The shaking table test is proceeding from x axis, y axis and x+y axis with different amplitude of acceleration values. The results show that, to non-isolated model, the natural vibration period is remarkably decreased and entered non-linear condition after moderate earthquake. Its accelerations become lager with increasing storey number and completely collapsed under large earthquake. The inter-storey shifts largely exceed the limit values of regulated displacement angles. But to isolated model, the natural vibration period of isolated modal is almost the same in all conditions and still in its elastic condition. The earthquake loading is greatly reduced and the accelerations of superstructure are greatly reduced. The inter-storey drifts are very small and can be neglected. The isolated model is in translational state and can be seen as a rigid whole. The displacements of isolation layer are in the allowable range. This experiment demonstrates that the seismic isolation is very effective to mitigate the influence of earthquake on structures and it is possible to increase the serviceability due to decrease the floor acceleration. facilities from their good states that is superior to non-isolated structure.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.2
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• pp.161-169
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• 2004

This paper deals with system identification of a three-story building model with active mass damper (MID) for the controller design. Observer Kalman filter identification (OKID) technique is applied to find the relationship between the experimental results of the input and output. The inputs to the building model with MID are ground accelerations and motor command signal, which are, respectively, simulated earthquake and equivalent control force. The outputs are each floor acceleration and MID acceleration. The MID controller is designed based on the experimentally identified building system. Finally it is shown that experimental results agree accurately with simulated results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.65-74
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• 2019

This study presents the optimal isolation period according to the number of vertically expended stories in order to provide the basic data for the application of the seismic isolation system in the vertically expended remodeling of the aged apartment. As a result of the structural analysis, the isolation period should be at least twice the primary structure in three-story vertical expansion, three times in two-story expansion, and four times in one-story expansion for the effective application of the isolation system. On the basis of the result, the efficacy of an isolation system for the actual apartment structure, which is three-story vertically expended, was analytically verified. The maximal acceleration response on the top floor reduced by 70% and 65% of the non-isolated structure in the X and Y directions respectively. Additionally, the base shear force decreased by 30% in the both directions, compared to the non-isolated structure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.5
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• pp.107-115
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• 2014

In this study, we examined the seismic isolation effects due to the difference between the center of mass of the building and the center of stiffness of isolation layer. Because the base isolation technique is a technique that is highly dependent on the performance of seismic isolation devices installed on the seismic isolation layer, we have to examine the horizontal stiffness of seismic isolation devices after making them. If difference between the design stiffness and the actual stiffness of the seismic isolation device occurred, a big problem may be generated in the upper members on the seismic isolation layer. The analytical results show that the more eccentricity increases, the more maximum response acceleration, story shear and the member forces of the upper part of the structure increases, and the damage is expected to be in excess. Therefore, it is recommended that if possible, isolation devices have to be designed to coincide the center of mass of the building with the center of stiffness of isolation layer. If not after making isolation devices, they need to be relocated to prevent the eccentricity.

• Journal of Korean Association for Spatial Structures
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• v.11 no.4
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• pp.79-88
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• 2011

Recently, complex-shaped tall buildings represented by 3T(Twisted, Tapered, Tilted) are planed largely. A diagrid structural system is one of the most widely used structural system for complex-shaped tall buildings because of its structural efficiency and formativeness. Plans for tilted tall buildings are largely presented because of beauty of a sculpture and many of buildings use diagrid structural systems. Lateral displacements of tilted tall buildings are induced by not only lateral loads but also self weight. Therefore, reduction of lateral responses of tilted tall buildings is as important as typical tall buildings. In this study, a smart TMD is introduced to reduce seismic responses of tilted diagrid tall buildings and its control performance is evaluated. MR damper is employed for the smart TMD and ground-hook controller is used as a control algorithm for the smart TMD. 100-story tall building is used as an example structure. Control performances of uncontrolled case, controlled case with TMD and controlled case with smart TMD are compared and investigated. Numerical simulation has shown that smart TMD presented good control performance for displacement response but acceleration response was not controlled well.

• Journal of Sensor Science and Technology
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• v.5 no.5
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• pp.21-29
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• 1996

A piezoresistive silicon acceleration sensor with 8 beams, utilized by an unique silicon micromachining technique using porous silicon etching method which was fabricated on the selectively diffused (111)-oriented $n/n^{+}/n$ silicon subtrates. The width, length, and thickness of the beam was $100\;{\mu}m$, $500\;{\mu}m$, and $7\;{\mu}m$, respectively, and the diameter of the mass paddle (the region suspended by the eight beams) was 1.4 mm. The seismic mass on the mass paddle was formed about 2 mg so as to measure accelerations of the range of 50g for automotive applications. For the formation of the mass, the solder mass was loaded on the mass paddle by dispensing Pb/Sn/Ag solder paste. After the solder paste is deposited, Heat treatment was carried out on the 3-zone reflow equipment. The decay time of the output signal to impulse excitation of the fabricated sensor was observed for approximately 30 ms. The sensitivity measured through summing circuit was 2.9 mV/g and the nonlinearity of the sensor was less than 2% of the full scale output. The output deviation of each bridge was ${\pm}4%$. The cross-axis sensitivity was within 4% and the resonant frequency was found to be 2.15 KHz from the FEM simulation results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.4
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• pp.838-845
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• 2009

The inelastic response characteristics of the standard school buildings depending on selection of hysteresis models are reviewed. Three earthquake records of El-centre, Santa-Monica, Taft and three artificial earthquake records in accordance with Korea standard are used and the inelastic response characteristics such as story shear force, story drift ratio, story displacement, hinge distribution state are reviewed with various hysteresis models. As results, story shear force is increased by maximum 60% according to hysteresis model. And Story drift ratio is increased by maximum 42% according to hysteresis model. And The result with clough model shows the maximum hinge distribution state.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.1
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• pp.174-182
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• 2014

To monitor the wind-induced responses of buildings, conventional real-time kinematic (RTK) methods based on two global positioning system (GPS) receivers (e.g., a reference and a rover) are widely applied. However, these methods can encounter problems such as difficulty in securing and maintaining a space for a reference station. With the recently developed virtual reference station (VRS)-RTK approach, the position of a structure can be measured using only a rover receiver. In this study, to evaluate the applicability of VRS-RTK methods in monitoring the lateral structural responses of frame structures, we performed free vibration tests on a one-story frame model (the first natural frequency of 1 Hz) and a three-story frame model (the first natural frequency of 0.85 Hz). To assess the reliability of the displacement and acceleration responses measured by the GPS, we performed a concurrent measurement using laser displacement sensors and an accelerometer. The accelerometer results were consistent with the GPS measurements in terms of the time history and frequency content. Furthermore, to derive an appropriate sampling rate for the continuous monitoring of buildings, the errors in the displacement responses were evaluated at different GPS sampling rates (5, 10, 20 Hz). The results indicate that as the sampling rate increased, the errors in the displacement responses decreased. In addition, in the three-story model, all modal components (first, second, and third modes) could be recorded at a sampling rate of 20 Hz.