• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.1
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• pp.171-180
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• 2005

In this study the seismic performance of a three-story knee-braced moment-resisting frame (KBMRF), which is typically employed to support pipelines for oil or gas, was investigated. Nonlinear static pushover analyses were performed first to observe the force-displacement relationship of KBMRF under increasing seismic load. The results show that, when the maximum inter-story drift reached 1.5% of the story height, the main structural members, such as beams and columns, still remained elastic. Then nonlinear dynamic time-history analyses were carried out using eight earthquake ground motion time-histories scaled to at the design spectrum of UBC-97. It turned out that the maximum inter-story drift was smaller than the drift limit of 1.5 % of the structure height, and that the columns remained elastic. Based on these analytical results, it can be concluded that the seismic performance of the structure satisfies all the requirements regulated in the seismic code.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.6
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• pp.113-119
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• 2016

In this study, the method to predict the lateral response by using strain data is presented on the steel moment frame. For this, the reliability of the proposed method by applying the example of five-story frame structure were verified. Using the strain value of columns, it predicted the lateral response of structure. It is assumed that all of four strain sensors for one column set up and the strain responses of both end of the column are utilized. The lateral response of member is calculated by using the slope deflection method. Also, using the acceleration response of the one layer, the stiffness of the rotation spring located in the supporting point is predicted. As a result, it was effective to understand the lateral displacement and acceleration responses and to predict local damage and location.

• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.2
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• pp.13-24
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• 2000

최근 국내에서 많이 건설되어지고 있는 주상복합 건축물은 하부의 골조형식과 상부의 벽식 구조가 결합된 구조형식을 가지고 있다 따라서 지진 발생시 동일한 형식을 가진 건축물과는 상이하고 복잡한 반응을 보이게 된다 이러한 건축물의 등가정적 해석시 국내 규준에서는 기타구조물로 분류하여 3.5 의 반응수정계수를 적용하고 있다 그러나 이 계수는 검증되어지지 않는 상태로 사용되어지고 있으므로 상당한 위험성을 내포하고 있다 본 연구에서는 단순화한 주상복합 건물의 해석 및 실제의 건물에 대한 3차원 비선형 해석을 통하여 반응수정계수를 유도하였다 유도된 반응수정계수는 ATC 기준과 우리나라 기준의 차이를 고려한 보정을 수행하였다.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.1
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• pp.55-62
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• 2002

The upper wall-lower frame structures(mixed building structures) are usually composed of shear wall structure in the upper part of structure which is used as residential space and frame structure in the lower part of structure which is used as commercial space centering around the transfer system in the lower part of structure. These structures are characteristics of stiffness irregularity, mass irregularity, and vertical geometric irregularity. The purpose of this study is to investigate the nonlinear response characteristics and the seismic capacity of mixed building structures when the number of stories in the lower frame is varied. The conclusions of this study are following. 1) As the result of push-over analysis of structure such as roof drift(i.e. roof displacement/structural height) and base shear coefficient, when the stories of lower frame system are increased, base shear coefficient is decreased, but roof drift is increased. 2) According to an increase in stories of the lower fame, story drift and ductility ratio of upper wall system are decreased and behavior of upper wall system is closed to elastic. 3) When the stories of lower frame system are increased, the excessive story drift is concentrated on the lower frame system.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.2
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• pp.148-153
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• 2018

In this study, the nonlinear time history analysis of seismic retrofitted structures with TS damper for seven ground motion records was conducted for the purpose of verifying the seismic strengthening effect of TS seismic retrofitting method. Through comparison of the interstory drift ratio and the energy dissipation amount of the non - reinforced structure obtained and those of retrofitted structures with TS damper from the nonlinear time history analysis, the interstory drift ratio was reduced by about 30% and the amount of energy dissipation through the structure was halved. As a result, it was confirmed that the damping performance of the TS seismic retrofitting method is excellent.

• Magazine of the Korea Concrete Institute
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• v.13 no.6
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• pp.121-126
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• 2001

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.1
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• pp.29-37
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• 2004

The overstrength factor and the ductility factor are the two important factors that determine response modification factors used in current seismic codes, In this paper the overstrength and ductility factors of special concentric braced frames are determined by performing pushover analysis of model structures with various stories and span lengths. and by using those factors the response modification factors are obtained. According to the analysis results. the overstrength and the ductility factors are larger than the values proposed by the codes in low-rise structures. and the opposite is true in medium to high-rise structures, It is also found that the factors increase as the height of structures decreases and the span length increases.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.3
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• pp.293-300
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• 2015

In this study, a series of forced vibration testing and ambient vibration measurement were performed at a lowrise masonry-infilled reinforced concrete frame structure before and after seismic retrofit and its dynamic properties were extracted using system identification techniques. Also, analytical models which show similar dynamic properties to the measures ones were constructed. The system identification results showed that damping ratios in x direction along which the dampers were installed has been increased. From the comparison between the analytical models, the effective stiffness of post-installed member and post-reinforced members(shear walls and damper frames) were only 50% of gross sectional stiffness of the members, which indicates that the these members were not fully integrated with the existing structure or members. In addition, support condition of post-installed footing has to be pinned in y direction to match the dynamic properties, which is seemingly caused by the change of fixity of the soil due to the installation of new footing.

• Journal of the Korea Concrete Institute
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• v.24 no.5
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• pp.517-524
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• 2012

In this study, the effects of the inelastic shear behavior of beam-column joint and the vertical distribution of lateral load are evaluated considering higher modes on the response of RC OMRF using the pushover analysis. A structure used for the analysis was a 5-story structure located at site class SB and seismic design category C, which was designed in accordance with KBC2009. Bending moment-curvature relationship for beam and column was identified using fiber model. Also, bending moment-rotation relationship for beam-column joint was calculated using simple and unified joint shear behavior model and moment equilibrium relationship for the joint. The results of pushover analysis showed that, although the rigid beam-column joint overestimated the stiffness and strength of the structure, the inelastic shear behavior of beam-column joint could be neglected in the process of structural design since the average response modification factor satisfied the criteria of KBC2009 for RC OMRF independent to inelastic behavior of joint.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.4
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• pp.116-124
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• 2011

RC frames with unreinforced masonry infiledl walls are common in worldwide. Since infilled walls are normally considered as non-structural elements, their presence is often ignored by engineers. In this study, to improve the seismic performance of masonry walls, hexagonal block was developed and the influence of masonry infilled wall on the seismic performance of reinforced concrete(RC) frames that were designed in accordance with current code provisions without the consideration of earthquake loadings are investigated. Two 1/2 scale, single story, single bay, frame specimens were tested. The parameters investigated included that the strength of infilled wallls with respect to that of the lateral load history. The experimental results indicate that infilled walls can significantly improve the lateral stiffness and strength of RC frames. The lateral loads developed by the infilled frame specimen is higher than that of the bare frame. It also indicates that infilled walls can be potentially used to improve the performance of existing nonductile frames. For this purpose. methods should be developed to avoid irreparable damage and catastrophic failure.