• Journal of the Architectural Institute of Korea Structure & Construction
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• v.36 no.5
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• pp.137-146
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• 2020

In this study, an experimental research was performed to find the characteristics of the lateral load resistance of perforated steel plates which could be developed to retrofit existing RC framed buildings. The Specimens are tested with variables such as aspect ratio of plate, the ratio of perforation area, and the ratio of perforated diameter to strip which is more than 0.6. The lateral load was applied with displacement control until to reach 3.5% drift ratio. Through the experimental results, it was shown that the maximum strength of all specimens were reached at around 0.5% drift ratio and maintained until 3.5% drift ratio. From results, the modified strength prediction formula was derived with the variable ratio of the perforated diameter to strip. To evaluate seismic retrofit performance of RC frames using perforated steel plate, a simple design process was presented.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.400-403
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• 2010

Mega-frame 시스템은 구조적으로 횡력에 가장 효율적으로 저항할 수 있는 구조시스템으로서 200층 이상의 극초고층 건물에 적용되고 있다. 소수의 대형 기둥에 의하여 지지되므로, 기둥의 파괴로 인한 연쇄붕괴의 가능성이 매우 높다. 본 논문에서는 비선형 정적해석을 통하여 다양한 Mega-frame 구조물의 연쇄붕괴 저항능력을 평가해 보았다. 그 결과, Mega-frame 구조물의 연쇄붕괴 거동을 이해하고 이에 합당한 연쇄붕괴 보강방안을 찾으려 한다.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.4
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• pp.29-36
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• 2010

To investigate the cyclic characteristics of exterior joints in RC frame buildings which are typically used after 1988, 70% scaled T-shaped beam-column subassemblies were designed and tested with a displacement control that is composed of 9 steps, until 3.5% story drift was reached. Axial forces are applied to columns during the experiment to simulate a real situation. The results show that the non-seismic detailed specimens failed before reaching 0.85% story drift, and their strengths are less than 0.85 times the nominal flexural strength which beam or columns should reach. The relationship of principal stress and story drift of exterior joints is similar to the one that Priestly proposed.

• Journal of the Korea Concrete Institute
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• v.20 no.1
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• pp.35-41
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• 2008

In general, flat plate systems have been used as a gravity load resisting system (GLRS) in building. Thus, this system should be constructed with lateral force resisting system (LFRS) such as shear walls and brace frames. GLRS should retain the ability to undergo the lateral drift associated with the LFRS without loss of gravity load carrying capacity. And flat plate system can be designed LFRS as ordinary moment frame with the special details. Thus, flat plate system designed as GLRS or LFRS should be considered internal forces (e.g., unbalanced moments) and lateral deformation generated in vicinity of slab joints render the system more susceptible to punching shear. ACI 318 (2005) allows the direct design method, equivalent frame method under gravity loads and allows the finite-element models, effective beam width models, and equivalent frame models under lateral loads. These analysis methods can produce widely different result, and each has advantage and disadvantages. Thus, it is sometimes difficult for a designer to select an appropriate analysis method and interpret the results for design purposes. This study is to help designer selecting analysis method for flat plate system and to verify practicality of the modified equivalent frame method under lateral loads. This study compared internal force and drift obtained from frame methods with those obtained from finite element method under gravity and lateral loads. For this purposes, 7 story building is considered. Also, the accuracy of these models is verified by comparing analysis results using frame methods with published experimental results of NRC slab.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.3
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• pp.255-266
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• 2010

In high-rise buildings, an outrigger system is frequently used as a resisting system for lateral loads. Since the outriggers tie exterior columns and an interior core, exterior columns can participate in the lateral load resisting system and the structural resistance capacity can be increased. However, the outriggers contribute for controlling gravity loads as well as lateral loads. The flows of gravity loads can be changed by the members of outriggers, for the purposes of transferring loads to mega-columns, distributing gravity loads equally among vertical members of columns, walls, or piles, minimizing differential settlements in a foundation system, and so on. In this study, by computational structural analyses of high-rise buildings over 100 floors, the effects of outriggers on controlling gravity loads are analyzed. Analyses for 3-dimensional models with or without outrigger members are performed, and then the gravity load distributions in columns and piles and foundation settlements are analyzed. Also, the effects of outriggers on gravity load controls during construction stages as well as after construction are included.

• Journal of Korean Society of Steel Construction
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• v.21 no.4
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• pp.375-384
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• 2009

The application of the diagrid structural system has increased of late, but cyclic loadings such as winds and earthquakes cannot be fully understood through only an analytical study due to the difficulty of considering its welding property. In this study, diagrid nodes that had been scaled down to 1/5 of their full sizes were tested to find out their structural behavior under seismic or wind loads. Four specimens were used with five parameters, including the welding method and the design details. Cyclic loading tests were carried out, where a tensile load was applied to one brace member and a compression load to the other. The major failure modes in the tests were only failure of bending with tensile stress and tension failure. The welding method and the design details had no effect on the initial stiffness and yielding stress but play a significant role in the failure mode and energy dissipation, respectively.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.6
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• pp.205-214
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• 2010

Masonry structures have been used throughout the world for the construction of residential buildings. However, from a structural point of view, the masonry material is characterized by a very low tensile strength. Moreover, the bearing and shear capacity of masonry walls have been found to be vulnerable to earthquakes. In this study, to improve the seismic performance of masonry walls, hexagonal blocks were developed and six masonry walls made with hexagonal block were tested to failure under reversed cyclic lateral loading. This paper focuses on an experimental investigation of different types of wall with hexagonal blocks, i.e. walls with different hexagonal blocks and with different reinforcing bar arrangements, subjected to applied cyclic loads. The cracking, damage patterns and hysteretic feature were evaluated. Results from the hexagonal masonry wall were shown more damage reduction and less brittle failure in comparison to the existing rectangular masonry walls.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.1
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• pp.72-84
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• 2016

The conventional brace system is generally accepted as the lateral load resisting system for steel structures due to efficient story drift control and economic feasibility. But lateral stiffness of the structure decreases when buckling happens to the brace in compression, so that it results in unstable structure with unstable hysteresis behavior through strength deterioration. Buckling restrained brace(BRB) system, in which steel core is confined by mortar/concrete-filled tube, represents stable behavior in the post-yield range because the core's buckling is restrained. So, seismic performance of BRB is much better than that of conventional brace system in point of energy absorption capacity, and it is applied the most in high seismicity regions as damper element. BRBs with various shaped-sections have been developed across the globe, but the shapes experimented in Korea are now quite limited. In this study, we considered built-up type of restraining member made up of precast reinforcement concrete and the steel core. we experimented the BRB according to AISC(2005) and evaluated seismic performances and hysteresis characteristics.

• Journal of Korean Society of Steel Construction
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• v.17 no.5 s.78
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• pp.617-625
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• 2005

The brace is often used to resist lateral force such as that exerted by an earthquake. Because of buckling at bifurcation load, the brace shows unstable hysteretic characteristics in the plastic zone. Therefore, in this study, the brace with damper that consists of slit plates were suggested on the purpose of preventing buckling and increasing plastic deformation capacity. The experimental results regarding the brace member were analyzed and the feasibility was also examined.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.459-460
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• 2009

The purpose of this study is to develop precast concrete structural wall panel that can assure reliable seismic performance. In the previous study, the connection of precast concrete structural wall has some problems in seismic performance. Therefore, this research proposed the precast concrete structural walls which can improve seismic performance. And their seismic performance was verified through lateral loading experiment.