• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.593-598
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• 2002

Routinely, strength method for the determination of the nominal moment of reinforced concrete beam is assumed to also be suitable for strengthening beams with carbon fiber sheets since typically strengthening beams compromise 98% by volume of reinforced concrete. Flexural capacity of strengthening beam is absolutely dependent upon the type of reinforcement materials, amount of reinforcement, anchoring system, adhesion capacity between reinforcement material and concrete. Therefore, it might be incorrect to use strength method for analysis and design of strengthening beam without considering the differences in the load-deflection curves, mechanism of failure, state of stress distribution, failure strain of the reinforcement. An flexural analysis based on force equilibrium and strain comparability has been developed for strengthening beam. Systematic experimental investigations are compared with analytical results. Then, the adaptation of strength method for strengthening beam have also been discussed.

• Steel and Composite Structures
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• v.10 no.5
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• pp.373-383
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• 2010

This paper presents the experimental studies of the flexural behavior of steel-concrete composite beams. Herein, steel-concrete composite beams were constructed with a welded steel I section beam and concrete slab with different material strength. Four simply supported composite beams subjected to two-point concentrated loads were tested and compared to investigate the effect of high strength engineering materials on the overall flexural response, including failure modes, load deflection behavior, strain response and interface slip. The experimental results show that the moment capacity of composite beams has been improved effectively when high-strength steel and concrete are used. Comparisons of the ultimate flexural strength of beams tested are then made with the calculated results according to the methods specified in guideline Eurocode 4. The ultimate flexural strength based on current codes may be slightly unconservative for predicating the moment capacity of composite beams with high-strength steel or concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.535-540
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• 2000

When the stud connection is considered as pin joint in the practical design, it is required to have high deformability. The rotational capacity as well as moment of the connection are evaluated through experimental works. Considered in the test are the reinforcement ratios of concrete member, the magnitude of axial force and connection details. It is shown that the stud connection has some quantity of moment capacity buy on the other hand it has low deformability. The strength and deformability of the connection depend on the axial force and reinforcements around the studs. The strength and ductility of the connection ate increased by using closed C-type.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.569-574
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• 1997

This research has improved composite joint system of R/C column and steel beam developed at previous study. In this system, the shear force occurred at beam is transmitted by bearing resistance of stiffness and moment is resisted by tension capacity of coupling members. As the preliminary step of stress transfer tests of this system, welding performance test of coupling member such as round bar or square bar which has a role of moment transfer has been carried out. From the test, this element has a good welding performance and enough resistance capacity compared to design force.

• Steel and Composite Structures
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• v.22 no.1
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• pp.183-201
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• 2016

Perforated steel beams can be optimised by increased beam depth and the moment of inertia combined with a reduced web thickness, favouring the use of original I-section beams. The designers are often confronted with situations where optimisation cannot be carried out effectively, taking account of the buckling risk at web posts, moment-shear transfers and local plastic deformations on the transverse holes of the openings. The purpose of this study is to suggest solutions for reducing these failure risks of tested optimal designed beams under applying loads in a self-reacting frame. The design method for the beams is the hunting search optimisation technique, and the design constraints are implemented from BS 5950 provisions. Therefore, I have aimed to explore the strengthening effects of reinforced openings with ring stiffeners, welded vertical simple plates on the web posts and horizontal plates around the openings on the ultimate load carrying capacities of optimally designed perforated steel beams. Test results have shown that compared to lateral stiffeners, ring and vertical stiffeners significantly increase the loadcarrying capacity of perforated steel beams.

• Journal of Korean Association for Spatial Structures
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• v.15 no.1
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• pp.47-55
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• 2015

This paper shows the simplified equation to predict the ultimate moment capacity and corresponding rod stress in reinforced concrete beam with external post-tensioning rods. Because the stress of external post-tensioning rod depends on the beam deflection, the previous analytical model for post-tensioned beams requires a tedious iteration process. Also, the stress equations in ACI code or other researchers' models are suitable only for internal tendons in concrete beams. In this study, given the lack of analytical approaches to predict the nominal stress of the external unbonded rod, a simple and robust equation has been proposed for externally post-tensioned concrete beams. It is concluded that the proposed equation predicted the stress of external steel rods in post-tensioned concrete beams reasonably well.

• Structural Engineering and Mechanics
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• v.3 no.5
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• pp.463-474
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• 1995

When a tubular cantilever beam is loaded by a dynamic force applied transversely at its tip, the strain hardening of the material tends to increase the load carrying capacity and local buckling and cross-sectional overlization occurring in the tube section tends to reduce the moment carrying capacity and results in structural softening. A theoretical model is presented in this paper to analyze the deformation of a tubular beam in a dynamic response mode. Based on a large deflection analysis, the hardening/softening M-${\kappa}$ relationship is introduced. The main interest is on the curvature development history and the deformed configuration of the beam.

• Earthquakes and Structures
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• v.9 no.6
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• pp.1291-1311
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• 2015

This study investigates the seismic energy dissipation capacity of a hybrid passive damper composed of a friction and a hysteretic slit damper. The capacity of the hybrid device required to satisfy a given target performance of a reinforced concrete moment resisting frame designed with reduced design base shear is determined based on the ASCE/SEI 7-10 process, and the seismic performances of the structures designed without and with the hybrid dampers are verified by nonlinear dynamic analyses. Fragility analysis is carried out to investigate the probability of a specified limit state to be reached. The analysis results show that in the structure with hybrid dampers the residual displacements are generally reduced and the dissipated inelastic energy is mostly concentrated on the dampers. At the Moderate to Extensive damage states the fragility turned out to be smallest in the structure with the hybrid dampers.

• Steel and Composite Structures
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• v.18 no.3
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• pp.641-657
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• 2015

Application of reduced web beam section (RWBS) as a sacrificial fuse element has become a popular research field in recent years. Weakening of beam web in these connections may cause local web buckling around the opening area which can affect cyclic behavior of connection including: maximum load carrying capacity, strength degradation rate, dissipated energy, rotation capacity, etc. In this research, effect of local web buckling on the cyclic behavior of RWBS connections is investigated using finite element modeling (FEM). For this purpose, a T-shaped moment connection which has been tested under cyclic loading by another author is used as the reference model. Fracture initiation in models is simulated using Cyclic Void Growth Model (CVGM) which is based on micro-void growth and coalescence. Included in the results are: effect of opening corner radii, opening dimensions, beam web thickness and opening reinforcement. Based on the results, local web buckling around the opening area plays a significant role on the cyclic behavior of connection and hence any parameter affecting the local web buckling will affect entire connection behavior.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.03a
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• pp.349-361
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• 2003

For performance-base design using nonlinear static analysis, it is required to predict the inelastic behavior of structural members accurately. In the present study, nonlinear numerical analysis was performed to develop the method describing the moment-curvature relationship of structural wall with boundary confinement. Through the numerical analysis, variations of behavioral characteristics and failure mechanism with the arrangement of vertical reiforcement and the length of boundary confinement were studied. Based on the findings, moment-curvature curves and curvature capacity for walls with a variety of re-bar arrangement was developed. By equalizing curvature capacity to demand, a design method which can determine the length of boundary confinement, was developed and for the effectiveness of boundary confinement and constructability, boundary confinement detail was proposed.