• Earthquakes and Structures
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• v.5 no.4
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• pp.379-394
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• 2013

Post-earthquake fire (PEF) can lead to a rapid collapse of buildings damaged partially as a result of prior earthquake. Almost all standards and codes for the design of structures against earthquake ignore the risk of PEF, and thus buildings designed using those codes could be too weak when subjected to a fire after an earthquake. An investigation based on sequential analysis inspired by FEMA356 is performed here on the Immediate Occupancy, Life Safety and Collapse Prevention performance levels of structures, designed to the ACI 318-08 code, after they are subjected to an earthquake level with PGA of 0.35g. This investigation is followed by a fire analysis of the damaged structures, examining the time taken for the damaged structures to collapse. As a point of reference, a fire analysis is also performed for undamaged structures and before the occurrence of earthquake. The results indicate that the vulnerability of structures increases dramatically when a previously damaged structure is exposed to PEF. The results also show that the damaging effects of post-earthquake fire are exacerbated when initiated from the second and third floor. Whilst the investigation is made for a certain class of structures (conventional buildings, intermediate reinforced structure, 3 stories), the results confirm the need for the incorporation of post-earthquake fire into the process of analysis and design, and provides some quantitative measures on the level of associated effects.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.887-890
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• 2005

The earthquake test Procedures specified in three international codes were reviewed and compared for the network equipments. As technical level on the electronics and networking is growing in Korea, many related equipments are required to export to abroad. The network equipments are now essential tools for communication among individuals as well as societies, especially at the hazard situation such as earthquake strike. The Korean network companies are trying to improve the earthquake resistance performance for their products to expand domestic and international markets. In this paper it is reviewed that most codes related on the earthquake tests can be performed with the facilities provided in Korea for the network equipments. However new facility is required to prepare for more performance and higher regulating codes expected.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.3 s.49
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• pp.125-134
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• 2006

Conventional methods for the assessment of liquefaction potential were primary for severe earthquake regions $(M{\geq}7.5)$ such as North America and Japan. In Korea, an earthquake related research has started in 1997, but most contents in the guidelines were still quoted from literature reviews of North America and Japan, which are located in strong earthquake region. Those are not proper in a moderate earthquake regions including Korea. Also the equivalent uniform stress concept (Seed & Idriss, 1971) using regular sinusoidal loading which is used, in a conventional method for the assessment of liquefaction potential, can't reflect correctly the dynamic characteristics of real irregular earthquake motions. In this study, cyclic triaxial tests using irregular earthquake motions are performed with different earthquake magnitudes, relative densities, and fines contents. Assessment of liquefaction potential in moderate earthquake regions is discussed based on various laboratory test results. From the results, screening limits in seismic design were re-investigated and proposed using normalized maximum stress ratios under real irregular earthquake motions. Also from the tests using constant wedge loading and incremental wedge loading, the characteristics of liquefaction resistance of saturated sand under irregular ground motions are investigated.

• Structural Engineering and Mechanics
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• v.58 no.1
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• pp.39-58
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• 2016

Since the publication of ACI 318-02, the concrete capacity design (CCD) method has been used to determine the resistance of unreinforced concrete anchors. The regulation of steel-reinforced anchors was proposed in ACI 318-08. Until ACI 318-08, the shear resistance of concrete breakout for an unreinforced anchor during an earthquake was reduced to 75% of the static shear strength, but this reduction has been eliminated since ACI 318-11. In addition, the resistance of a hairpin-reinforced anchor was calculated using only the strength of the steel, and a regulation on the dynamic strength was not given for reinforced anchors. In this study, shaking table tests were performed to evaluate the dynamic shear strength of unreinforced and hairpin-reinforced cast-in-place (CIP) anchors during earthquakes. The anchors used in this study were 30 mm in diameter, with edge distances of 150 mm and embedment depths of 240 mm. The diameter of the hairpin steel was 10 mm. Shaking table tests were carried out on two specimens using the artificial earthquake, based on the United States Nuclear Regulatory Commission (US NRC)'s Regulatory Guide 1.60, and the Northridge earthquake. The experimental results were compared to the current ACI 318 and ETAG 001 design codes.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.343-346
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• 2005

Earthquake resistance design has been developed many countries like Japan, USA, Mexico, New Zealand etc., which countries have experienced many earthquakes. Nowadays, earthquake resistance design has come into worldwide use. In Korea, the seismic design regulations have been established since 1988 in order to minimize the economic losses. Recently performance based design method has been adopted as a new Earthquake resistance design method. These regulations, however, are targeted for newly constructed buildings, In Korea, there are no regulations for existing buildings that built before 1988. So, we need to prepare the regulations that evaluate the seismic performance, furthermore proper retrofitting design guideline needs to be proposed when remodeling old buildings. This study was performed that many existing apartments is being a Remodeling object when considering the present condition of existing apartment and the problems of cost and environment in the future plan. When Remodeling construction is reviewed by former the Seismic Performance Evaluation Method, generating problems is evaluation by using Push-over. According to this, it provides the appropriate method of calculating the Seismic Ship Performance Index.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.298-307
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• 2000

The behavior of a unreinforced cement brick building structure subjected to earthquake loading was experimentally investigated. for this four full size wall specimens were tested under quasi-static in-plane cyclic loading. Experimental observations indicate that the failure modes of unreinforced masonry walls are principally governed by sliding or/and rocking depending on the aspect ration and magnitude of axial loading. Also found was the flexure or shear mode resulting from the degraded strength of brick and/or mortar due to the cyclic loading effect.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.03a
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• pp.118-125
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• 2003

Seismic damage assessment program for containment structure is developed. The program has been established through the combination of inelastic seismic analysis program and 3-D animation program. Damage indices at finite element level and structural level have been introduced for the seismic damage assessment. The seismic damage assessment program makes it possible to analyze in real-time the actual resistance capacity and damage level of containment structure. It will be expected that the program enables to establish the measures more quickly under the earthquake event.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.4
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• pp.33-42
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• 2007

This paper describes the state-of-the art research activities on seismic isolation systems for improving the seismic capacities of the bridges in Korea. Though Korea is located in a region of low-to-moderate seismicity, the construction of seismic isolation systems has increased rapidly. The application of seismic isolation system has become popular worldwide because of its stable behavior and economical construction especially for bridge structures. Since optimal reliability level of isolated bridges can be determined as the one that provides the highest net life-cycle benefit to society, or the minimum Life-Cycle Cost (LCC), an optimal design procedure based on minimum LCC concept is more expedient for the design of seismically isolated bridges in areas of low-to-moderate seismicty. To verify the adequacy of the new design concept based on the LCC minimization, experimental studies on seismically isolated bridge are introduced as well, which include pseudo-dynamic test of scaled pier and dynamic field test of full-scale. With the application of seismic isolation systems, many kinds of dampers to improve the seismic capacity of structure are also applied not only to new bridges but also to existing bridges.

• Earthquakes and Structures
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• v.9 no.3
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• pp.639-656
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• 2015

Seismic isolation devices are commonly used to mitigate damages caused by seismic responses of structures. More damages are created due to progressive collapse in structures. Therefore, evaluating the impact of the isolation systems to enhance progressive collapse-resisting capacity is very important. In this study, the effect of lead rubber bearing isolation system to increase the resistance of structures against progressive collapse was evaluated. Concrete moment resisting frames were used in both the fixed and base-isolated model structures. Then, progressive collapse-resisting capacity of frames was investigated using the push down nonlinear static analysis under gravity loads that specified in GSA guideline. Nonlinear dynamic analysis was performed to consider dynamic effects column removal under earthquake. The results of the push down analysis are highly dependent on location of removal column and floor number of buildings. Also, seismic isolation system does not play an effective role in increasing the progressive collapse-resisting capacities of structures under gravity loads. Base isolation helps to localize failures and prevented from spreading it to intact span under seismic loads.

• Steel and Composite Structures
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• v.30 no.4
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• pp.351-364
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• 2019

Earthquake and fire are both severe disasters for building structures. Since earthquake-induced damage will weaken the structure and reduce its fire endurance, it is important to investigate the behavior of structure subjected to post-earthquake fire. In this paper, steel-concrete composite beam-to-column joints were tested under fire with pre-damage caused by cyclic loads. Beforehand, three control specimens with no pre-damage were tested to capture the static, cyclic and fire-resistant performance of intact joints. Experimental data including strain, deflection and temperature recorded at several points are presented and analyzed to quantify the influence of cyclic damage on fire resistance. It is indicated that the fire endurance of damaged joints decreased with the increase of damage level, mainly due to faster heating-up rate after cyclic damage. However, cracks induced by cyclic loading in concrete are found to mitigate the concrete spalling at elevated temperatures. Moreover, the relationship between fire resistance and damage degree is revealed from experimental results, which can be applied in fire safety design and is worthwhile for further research.