• Journal of Korean Society of Steel Construction
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• v.9 no.3 s.32
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• pp.341-350
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• 1997

The objective of this study is to investigate the structural behavior of the composite slabs with the new metal deckplate. The new deckplate can be used as structural member with topping concrete. So several experiments of this structural test and the fire resistance test were done. From this experiments. slabs with new metal deckpklate were verified as composite slabs. In this paper, this verifications were compared with the international design methods. For experiment. 49 specimens were made. the main parameters are deckplate thickness (1.2mm. 1.6mm) depth of topping concrete(85mm. 90mm). support condition(simple, 2-span), shear reinforcment(studs), span(2.7m, 3.0m, 3.3m. 3.6m. 3.9m) and shear span(L/3, L/4, L/7). We analyzed the structural behavior of composite slab throughout the moment-curvature relationship which is obtained with the program using the computer language. Turbo C. From this development for slab system, the reinforced concrete or steel structure building may be easy, economical for construction, And informations about the structural behavior of composite slabs will be utilized to established korea standard.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.2
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• pp.287-297
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• 2015

In concrete structural design provisons, there is a minimum allowable strain of steel to ensure a ductility of RC members and a c/d is limited for the same purpose in EC2. In general, a ductility capacity of RC members is evaluated by a displacement ductility which is a ratio of ultimate displacement to yield displacement, and it is necessary to calculate accurately a yield displacement and an ultimate displacement to evaluate a displacement ductility. But a displacement in members is affected by various member characteristics, so it is hard to calculate a displacement exactly. In this study, a displacement ductility is calculated by calculating a yield displacement and an ultimate displacement through a moment-curvature relationship. The main variables examined are concrete strength, yield strength, steel ratio, spacing of confinement, axial force ratio and concrete ultimate strain. As results, as a concrete strength is increased, a ductility displacement is increased. But as yield strength, steel ratio, spacing of confinement and axial force ratio are increased, a displacement ductility is decreased. And a displacement ductility is necessary to calculate a response modification factor (R) of columns for seismic design, so it is appeared that it is important to calculate a displacement ductility more accurately.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.1
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• pp.45-55
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• 2022

Because boundary confinement details proposed in the current design standards are significantly inferior in workability and production quality, it is necessary to develop boundary confinement details of RC structural walls that are capable of ensuring seismic performance and workability. With the recent development of the wire rod manufacturing technology, various pre-fabricated continuous hoop details can be manufactured. In this study, an analysis was conducted on the moment-curvature relationship of RC structural walls to which the pre-fabricated continuous hoop details were applied. According to the nonlinear cross-section analysis, the RC structure wall to which the details of the pre-fabricated continuous hoop details are applied can ensure seismic performance as the area of the pre-fabricated continuous hoop increases. Based on these research results, when applying the pre-fabricated continuous hoop in detail, it is necessary to secure the area of the pre-fabricated continuous hoop as much as the area of the existing boundary confinement.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.4
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• pp.100-107
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• 2018

The objective of this study is to assess the strengthening effects of fiber reinforced polymer(FRP) sheets such as Carbon fiber, Glass fiber, and PET(polyethylene terephthalate) on reinforced concrete flexural members. Variables of theoretical analysis are types of strengthening materials, material properties and amount of strengthening materials. A virtual flexural member without FRP sheets was created as a control specimen to understand the structural behavior of the non-strengthened specimen in terms of elastic and ultimate cross section. In total, 11 specimens including one non-strengthened and ten strengthened specimens were investigated. Various variables such as types of strengthening, strengthening properties, and amount of strengthening were studied to compare the behavior of the control specimen with those of strengthened specimens with regard to moment-curvature relationship. Results of theoretical analysis showed that the moment capacity of strengthened specimens was superior to that of the control specimen. However, the control specimen indicated the best ductility among all the specimens. As the amount of strengthening increased, flexural performance was improved. Furthermore, the results indicated that the ductile effect of members was affected by the ultimate strain of FRP sheets. The strengthening effect on the damaged member was similar to that on the non-damaged one since there was less than 10% difference in terms of flexural strength and ductility. Therefore, even if a damaged member is treated as non-damaged for analysis there is probably no noticeable difference.

• Journal of the Korea Concrete Institute
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• v.24 no.6
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• pp.633-641
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• 2012

In this study, the effects of the inelastic shear behavior of beam-column joint on the response of RC OMRF are evaluated in the inelastic time history analysis. For an example, a 5-story structure for site class SB and seismic design category C was designed in accordance with KBC2009. Bending moment-curvature relationship for beam and column was evaluated using fiber model and bending moment-rotation relationship for beam-column joint was calculated using simple and unified joint shear behavior model and moment equilibrium relationship. The hysteretic behavior was simulated using three-parameter model suggested in IDARC program. The inelastic time history analysis with PGA for return period of 2400 years showed that the model with inelastic beam-column joint yielded smaller maximum base shear force but nearly equivalent maximum roof displacement and maximum story drift as those obtained from analysis using rigid joint. The maximum story drift satisfied the criteria of KBC2009. Therefore, the inelastic shear behavior of beam-column joint could be neglected in the structural design.

• Journal of the Korea Concrete Institute
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• v.24 no.1
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• pp.15-23
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• 2012

This paper is about proposal of a calculation method and development of an analytical program for predicting crack width and deflection in structural concrete members. The proposed method numerically calculate stresses in steel rebar using a parabola-rectangle stress-strain curve and a modified tension stiffening factor considering the effect of the cover thickness. Based on the study results, a calculation method to predict crack width and deflection in reinforced concrete flexural members is proposed utilizing effective tension area and idealized tension chord as well as effective moment-curvature relationship considering tension stiffening effect. The calculation method was applied to the test specimens available in literatures. The study results showed that the crack width and deflections predicted by the proposed method were closed to the experimentally measured data compared the current design code provisions.

• Computational Structural Engineering
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• v.9 no.3
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• pp.199-207
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• 1996

When an initially straight thin cylinder is bent, there is a tendency for the cross section to flatten. This phenomenon was investigated by L.G. Brazier in 1927 and is called "Brazier Effect" or "Brazier Theory". The main characteristic is the reduction of carrying capacity due to the decrease of bending stiffness by shortening of thickness with the increase of external load. And the relationship of curvature-bending moment becomes a soft spring type as shown in Fig.2. In this paper, the Brazier theory on plate type structures is investigated from the following view points : (1) What is the Brazier effect? (2) the reason of the occurrence of the Brazier effect in plate type structures by using beam model and (3) factors which cause the brazier effect.

• Journal of the Korea Concrete Institute
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• v.20 no.4
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• pp.459-467
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• 2008

This paper describes a proposal for average crack width and immediate deflection calculation in structural concrete members. The model is mathematically derived from actual bond stressslip relationships and tension stiffening effect between reinforcement and the surrounding concrete, and the actual strains of steel and concrete are integrated respectively along the embedded length between the adjacent cracks so as to obtain the difference in the axial elongation. With these, a model for average crack width and immediate deflection in reinforced concrete flexural members are proposed utilizing difference in the axial elongation and average steel strain and moment-curvature relationship with taking account of bond characteristics. The model is applied to the test specimens available in literatures, and the crack width and deflections predicted by the proposal equation in this study are closed to the experimentally measured data compared the current code provisions.

• Structural Engineering and Mechanics
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• v.73 no.5
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• pp.529-542
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• 2020

As limited well-documented experimental data are available for assessing the attributes of different deformation components of flanged walls, few appropriate models have been established for predicting the inelastic responses of flanged walls, especially those of asymmetrical flanged walls. This study presents the experimental results for three large-scale T-shaped reinforced concrete walls and examines the variations in the flexural, shear, and sliding components of deformation with the total deformation over the entire loading process. Based on the observed deformation behavior, a simple model based on moment-curvature analysis is established to estimate flexural deformations, in which the changes in plastic hinge length are considered and the deformations due to strain penetration are modeled individually. Based on the similar gross shapes of the curvature and shear strain distributions over the wall height, a proportional relationship is established between shear displacement and flexural rotation. By integrating the deformations due to flexure, shear, and strain penetration, a new load-deformation analytical model is proposed for flexure-dominant flanged walls. The proposed model provides engineers with a simple, accurate modeling tool appropriate for routine design work that can be applied to flexural walls with arbitrary sections and is capable of determining displacements at any position over the wall height. By further simplifying the analytical model, a simple procedure for estimating the ultimate displacement capacity of flanged walls is proposed, which will be valuable for performance-based seismic designs and seismic capacity evaluations.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.5
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• pp.68-77
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• 2012

The joint of existing steel grid composite deck is composed of lap splice of reinforcing bar with end hooks and field-placed concrete. In this study, bending tests of deck joint composed of concrete shear key and high tension bolts are carried out for the design variable, concrete shear key strengthened with steel plate or not, and test results are compared with flexural performance of the existing deck joint. Test results showed that the mechanical deck joint has about 30% ~ 60% more ultimate bending strength than the existing joint. According to analysis results of moment-curvature relationship, the initial bending stiffness of the existing deck joint is some higher than that of mechanical joint. But, after crack failure the structural performance of the existing deck joint is rapidly reduced. Furthermore, the deck joint with the strengthened shear key with steel plate has more bending moment capacity than the deck joint without strengthening. And strengthening of shear key has positive influence on the increase of bending stiffness.