• Earthquakes and Structures
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• v.20 no.2
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• pp.133-148
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• 2021

The paper presents a simplified force-based seismic design procedure for the preliminary design of steel haunch retrofitting for the seismic upgrade of deficient RC frames. The procedure involved constructing a site-specific seismic design spectrum for the site, which is transformed into seismic base shear coefficient demand, using an applicable response modification factor, that defines base shear force for seismic analysis of the structure. Recent experimental campaign; involving shake table testing of ten (10), and quasi-static cyclic testing of two (02), 1:3 reduced scale RC frame models, carried out for the seismic performance assessment of both deficient and retrofitted structures has provided the basis to calculate retrofit-specific response modification factor Rretrofitted. The haunch retrofitting technique enhanced the structural stiffness, strength, and ductility, hence, increased the structural response modification factor, which is mainly dependent on the applied retrofit scheme. An additional retrofit effectiveness factor (ΩR) is proposed for the deficient structure's response modification factor Rdeficient, representing the retrofit effectiveness (ΩR=Rretrofitted /Rdeficient), to calculate components' moment and shear demands for the retrofitted structure. The experimental campaign revealed that regardless of the deficient structures' characteristics, the ΩR factor remains fairly the unchanged, which is encouraging to generalize the design procedure. Haunch configuration is finalized that avoid brittle hinging of beam-column joints and ensure ductile beam yielding. Example case study for the seismic retrofit designs of RC frames are presented, which were validated through equivalent lateral load analysis using elastic model and response history analysis of finite-element based inelastic model, showing reasonable performance of the proposed design procedure. The proposed design has the advantage to provide a seismic zone-specific design solution, and also, to suggest if any additional measure is required to enhance the strength/deformability of beams and columns.

• Journal of Acupuncture Research
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• v.18 no.1
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• pp.157-169
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• 2001

Objective : The purpose of this study is to investigate the effects on WBC counts and each differential of neutrophils, lymphocytes, monocytes in whole blood sample of each experimental Aqua-acupuncture treated mice groups PCortex Ulmi Pumilae(CU), Ramulus Cinnamomum(RC), Radix Achyranthes(RA), Apitoxin(BV), Calculus Bovis Fel Ursi Moschus compound(BUM). Materials & Method : All the BALB/c mice used in this study were bred and maintained in our pathogen-free mouse facility and were 6 weeks of age at the start of the experiment. The experimental model of arthritis was induced by injecting 300${\mu}g$/kg LPS to all mice knee joint. The each of Aqua-acupuncture(Cortex Ulmi Pumilae, Ramulus Cinnamomum, Radix Achyranthes, Apitoxin, Calculus Bovis Fel Ursi Moschus compound) was injected into GB34(陽陵泉) of mice groups every other day for 6 times. And the WBC counts and each differential of neutrophils, lymphocytes, monocytes were measured at the 3rd, 7th and 14th day after LPS injection. Results : 1. The WBC counts were significantly decreased compared with the control(CON) group in every Aqua-acupuncture groups at all days. And at the 14th day, BV & BUM groups were more significantly decreased than RA group. 2. The Neutrophil's ratio was significantty increased compared with the CON group in CU & RC groups at the 3rd day and RC group was more significant than CU group. But at the 7th and 14th day, every Aqua-acupuncture groups were significantly increased compared with the CON group and at the 7th day, RC group was more significant than RA, BV & BUM groups and at the 14th day, RC, BV & BUM groups were more significant than RA group. 3. The Lymphocyte's ratio was significantly decreased compared with the CON group in RC group at the 3rd day. At the 7th day, CU, RC & BV groups were significantly decreased compared with the CON group. At the 14th day, every Aqua-acupuncture groups were significantly decreased compared with the CON group and RC group was more significant than RA group, 4. The Monocyte's ratio was significantly decreased compared with the CON group in every Aqua-acupuncture groups at the 7th day. At the 14th day, BV & BUM groups were significantly decreased compared with the CON group. Conclusion : According to the above results, it was concluded that CU & RC groups were more effective at the early period of this experiment, and at the latter period, BV & BUM groups were more effective than others. RA group was less effctive than others.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.4
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• pp.355-362
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• 2009

Many of residential buildings, which have pilotis in lower stories to meet the architectural needs, are recently constructed in Korea. Usually, infill walls located in the upper stories of these buildings may cause a soft first story, which is very weak from the earthquake resistance. In the design of the buildings, the infill walls of upper stories are usually considered as non-structural elements and thus they are not included in the analytical model. However, the infill walls may affect the seismic behavior of the residential buildings. Therefore, the differences in seismic behaviors of RC buildings with and without masonry infill walls are required to be investigated. In this study, seismic fragility analyses were performed for masonry infilled low-rise RC moment-resisting frames. And seismic behaviors of RC moment-resisting frame with/without masonry infill walls were evaluated. Two types of structural system with the same frame and different allocation of infill walls are used to evaluate the influence of masonry infill walls on seismic behavior of RC moment-resisting frames. The infill walls were modeled as bi-equivalent diagonal struts. The fragility analyses show that the seismic performance of RC moment-resisting frames with soft story is below the desirable building seismic performance level recommended by current seismic codes, indicating high vulnerability of RC moment-resisting frames with soft story.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1993.04a
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• pp.141-148
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• 1993

In this paper, TVLEM is selected for the shear wall model which was proposed by Kabeyasawa and the characteristics of spring models composing TVLEM was studied. In axial stiffness spring model, the horizontal displacements when Kabeyasawa model and simple axial stiffness hysteresis model were used, were closely similar. When the large shear-displacement was occured, stiffness degrading model was more adquate to the shear wall modelling than OOHM. Also for the purpose of modelling the horizontally continuous wall, the seperational method for TVLEM was used. The results of nonlinear analysis by this method were closely similar to experimental results .

• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.47-50
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• 2000

DC Gummel-Poon SPICE model parameter extraction program has been implemented. This program extracts the parameters from measured data using Levenberg-Marquardt algorithm. Measured data consist of forward and reverse Gummel plot, forward and reverse output characteristics and RE and RC measurements.

• Journal of the Korea Concrete Institute
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• v.17 no.6 s.90
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• pp.993-1000
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• 2005

Various types of FRP materials have been applied for structural strengthening of RC beams in various forms. When CFRP plates are used, a premature failure used to occur before enough strengthening effect appears. This is primarily due to the rip-off of CFRP Plate attached on RC beams. Despite of numerous studies on the rip-off failure of externally strengthened RC beams, its failure mechanism is not definitely clarified yet. Investigations from literatures have shown that the rip-off failure is dependant on the vertical and shear stresses at the level of main reinforcements in RC beams. This study suggests an analytical model to Investigate the rip-off failure load based on the stress states at the level of main reinforcements. The proposed model is relatively simple and produces very comparable results to the test data. It is believed that the proposed model can be successfully used to provide more information on the rip-off failure mechanisms and its prevention.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.185-190
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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 with infilled shear wall have two different layouts of the plan : The one has symmetric plan and the other has unsymmetric plan. Then, this model was subjected to a series of earthquake excitations. The test results show that the layout of shear wall has the negligible effect on the natural period and the base shear coefficient, but great effect on the failure mode of beam-column joint at flexible side frame.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.259-264
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• 2002

This paper describes an attempt to develop a unified design approach for reinforced concrete short beam failing in shear based on a Arch Factor. Designing for short beam in shear is not as straightforward as designing for flexure due to the complicated interdependency of the variables involved and to the nonexistence of a rational theory tn current design code. Shear failure of reinforced concrete beams with stirrups is influenced greatly because of the actual geometrical shape(a/d) of the concrete and flexural reinforcement steel ratio, stirrup reinforcement ratio and concrete compression strength, size effect etc. The objective of this paper is to present a pilot study to develop a simplified physical model for estimating shear behavior of reinforced concrete short beams. The Key idea incorporated with this model is the Arch factor, introduced by Kim and White.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.873-878
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• 2002

This study is performed to investigate the behavior of multi-column piers and to evaluate the seismic performance. In this study, 3 types of scale model piers with 2-column are designed and tested by quasi-static load in both longitudinal and transverse directions. Each type of model consisting of 2 specimens has different reinforcement details in the lap splice of longitudinal bars and amount of transverse reinforcements. This paper reports that relatively large amount of ductility can be achieved by providing sufficient lap-splice length and transverse reinforcements with end hook even if longitudinal bars are lap spliced in the base of pier. But because multi-column piers have small longitudinal stiffness, careful consideration is needed in case of multi-span continuous bridges.

• Progress in Medical Physics
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• v.2 no.2
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• pp.175-182
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• 1991

A newly derived O$_2$ Saturation Model which can be adapted to the design and study of Artificial Lung and Blood Gas Calculator etc. is introduced on the basis of Electrical Equivalent Circuits. The presented 4 stage and 2 stage RC circuits have good correlatons with actual chemical reactions of Hemoglobin and Oxygen. However, from results of computer simulations, 2 stage equivalent model is more accurate than 4 stage and conventional O$_2$ saturation models.