• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.218-221
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• 2006

The past Korean Bridge Design Specifications have no limitation on the amount of lap splices of longitudinal bars in the plastic hinge zone of piers. A majority of bridge piers which have been non-seismically designed might have some lap splices in plastic hinge zone. Also a number of those piers in Korea have a low aspect ratio(height/section area). So, some problems such as low ductility behavior may happen. In this study, the real pier which was non-seismically designed and has a low aspect ratio was selected for the quasi-static tests. Two groups of full scaled RC pier models of which aspect ratios are about 2.26 and about 2.67 were fabricated. And then, quasi-static tests according to the drift level history method were implemented. From the test results, the failure of these test specimens have been shown in the complex shear-flexural or shear modes. The low aspect ratio and the lap splice have largely influenced on the seismic performance of bridge piers.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.83-84
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• 2009

The objectives of this study is to investigate the effect of cementitious composite properties, particularly strain hardening and multiple cracking, on the seismic performance of infill walls when subjected to displacement reversals. The investigation focuses mainly on the comparative behaviors of precast infill walls in terms of cracking mechanism.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.197-198
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• 2009

This study is the research appling the representative Displacement-Based Design which is the basic concept of Direct Displacement Based Design proposed by Chopra and Goel to original Reinforced Concrete structure and determining the thickness of retrofit Steel Jacket about the Maximum design ground acceleration, and developing the more improved Algorithm as well as program by the Retrofit Design method and Nonlinear analysis by the Performance design method before and after reinforcement appling the determined retrofit thickness.

• Earthquakes and Structures
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• v.3 no.6
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• pp.853-867
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• 2012

In this paper, a new type of passive energy dissipating system similar to added damping and stiffness (ADAS) and triangular added damping and stiffness (TADAS) is proposed and implemented in the analytical model of a building with hybrid structural system in the structure's base which we call it; Telescopic column. The behavior and performance of a high rise R.C. structure equipped with this system is investigated and compared with conventional base isolation systems such as rubber isolator bearings and friction pendulum bearings. For this purpose a series of ground acceleration records of the San Fernando, Long Beach and Imperial Valley earthquakes are used as the disturbing ground motions in a series of numerical simulations. The nonlinear numerical modeling which includes both material and geometric nonlinearities were carried out by using SAP2000 program. Results show suitable behavior of structures equipped with telescopic columns in controlling the upper stories drifts and accelerations.

• Earthquakes and Structures
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• v.3 no.6
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• pp.805-820
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• 2012

An enhanced and efficient methodology is proposed for evaluating the robustness of an uncertain structure with passive dampers. Although the structural performance for seismic loads is an important design criterion in earthquake-prone countries, the structural parameters such as storey stiffnesses and damping coefficients of passive dampers are uncertain due to various factors or sources, e.g. initial manufacturing errors, material deterioration, temperature dependence. The concept of robust building design under such uncertain structural-parameter environment may be one of the most challenging issues to be tackled recently. By applying the proposed method of interval analysis and robustness evaluation for predicting the response variability accurately, the robustness of a passively controlled structure can be evaluated efficiently in terms of the so-called robustness function. An application is presented of the robustness function to the design and evaluation of passive damper systems.

• Smart Structures and Systems
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• v.11 no.2
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• pp.199-215
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• 2013

During the service life of a structure, design complications and unexpected events may induce unforeseen vibrations. These vibrations can be generated by malfunctioning machinery or machines that are modified or placed without considering the original structural design because of a change in the intended use of the structure. Significant vibrations occurred at a natural gas plant cooling structure during its operation due to cavitation effect within the hydraulic system. This study presents findings obtained from the in-situ vibration measurements and following finite-element analyses of the cooling structure. Comments are made on the updated performance level and damage state of the structure using the results of these measurements and corresponding numerical analyses. An attempt was also made to assess the applicability of traditional displacement-based vulnerability estimation methods in the health monitoring of structures under vibrations with a character different from those due to seismic excitations.

• Earthquakes and Structures
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• v.17 no.6
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• pp.591-598
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• 2019

The most recent shaking experiences have demonstrated that the predictions of the seismic models are not always in agreement with the registered responses, especially in the face of extreme earthquakes. Records collected from 1960 to 2011 at a rock-like site are used to develop a neural network that permits to estimate peak ground accelerations via the magnitude, the focal depth, the site-source distance and a seismogenic zone. The neural model is applied to the 8th and 19th September 2017 events that hit Mexican territory and the obtained results show that the network is flexible enough to work appropriately to various conditions of intensity and sites-sources with remarkably predictive capacity. The neural-attenuation curves are compared with those obtained from Ground Motion Prediction Equations and their performance is assessed for events, in addition to the devastating Mexican events, from Japan, Taiwan, Chile and USA.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.04a
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• pp.461-470
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• 2003

This paper discusses a time domain controller, LQR, and a frequency domain controller, H₂, for optimal control of civil structures under seismic loads. Numerical simulations are performed on a three-story structure with Active Mass Driver (AMD), which is experimentally identified. Control effectiveness of each controller for the suppression of third floor acceleration responses is investigated when the similar maximum control force is used. Simulation results indicate that LQR is effective for acceleration response reduction while H₂ controller is efficient for utilizing control force.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.09a
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• pp.407-414
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• 2001

The severe shortage of the available sites in the highly developed downtown area in Korea necessitates the construction of high-rise buildings which meet the need of residence and commercial activity simultaneously. The objective of this study is to investigate the seismic performance of this type of building structures. For this purpose, two 1 :12 scale 17-story reinforced concrete model structures were constructed according to the similitude law, in which the upper 15 stories have a bearing-wall system while the lower 2-story frames have two different layouts of the plan The one is a moment-resisting frame system and the other is a moment-resisting frame system with a infilled shear wall. Then, this model was subjected to a series of earthquake excitations. The test results show that the existence of shear wall reduced the shear deformation at the piloti frame, but has almost the negligible effect on the reduction of the overturning-moment angle.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.197-204
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• 2002

The resent earthquakes in worldwide have caused extensive damage to highway reinforced concrete bridge piers. It has been observed in the Korean Peninsula that the number of minor or low earthquake motions have increased year by year. Since the concern about the earthquake hazards is increased, the objective of this research is to evaluate the damage of reinforced concrete bridge piers subjected to probable earthquake motions. Experimental investigation was conducted to study the seismic performance of the full-scale specimens in size D=1.2m H=4.8m, which were constructed with different longitudinal lap splice and loading pattern, through the quasi-static test and the pseudo-dynamic test. It is thought that this result could contribute to establish the retrofit decision-making and disaster planning of reinforced concrete bridge piers in earthquake regions. And it could be also possible to quantify the damage of reinforced concrete bridge piers under cyclic loading