• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.4
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• pp.449-455
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• 2011

Recently, international collaborative research which was organized at Bhabha Atomic Research Centre in India, was conducted to develop for pressure capacity and nonlinear behavior of PHWR 1/4 scale nuclear containment building between experimental test and numerical code. In this paper, a nonlinear finite element analysis was carried out in order to predict ultimate pressure capacity and nonlinear behavior of the 1/4 scale containment building. The 1/4 scale containment building is consisted of basemat, cylinder wall, dome and 4-buttress. For the finite element analysis, commercial program ABAQUS was used. Finite element models including concrete, rebar and tendon have been developed for assessment of ultimate pressure capacity and failure mode for nuclear containment building. From the analysis results, first crack of the concrete, the yielding of the rebar and ultimate capacity pressure occurred at $1.6P_d$(design pressure), $3.36P_d$ and $4.0P_d$, respectively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.858-861
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• 2014

This paper presents a simplified finite element tire model for vehicle dynamics analysis. The classical finite element tire model was too big to simulate dynamic properties of the tire. In the simplified model, number of nodes of the tire model was dramatically reduced, and thus its simulation time was several times less than the classical model. Bead, carcass, belt which have an important role to the dynamic characteristics of tire were replaced by simple axis symmetric membrane elements. Also the rebar element was deleted. The tire model has been verified by comparing vertical stiffness data of the simulation model to the test data.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1519-1525
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• 2011

Construction of the coping of reinforced concrete piers is very complicated due to heavy density of rebars and usually exposed to negligent accident. To correct these problems, coping is pre-assembled at the ground in pier coping pre-assembly method and recently a new method of rebar assembling has proposed in this study. For safety assessment of proposed method, small scale model test of railway bridge(PSC U-GIRDER T-shaped pier) was carried out and it was verified that crack pattern, failure mechanism and load resistance capacity are similar between existing method and proposed method. And using analytical approach, linear and non-linear finite element analysis was performed. As a result, it was checked that proposed method has an acceptable structural safety.

• Nuclear Engineering and Technology
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• v.32 no.2
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• pp.180-190
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• 2000

In this study, nonlinear analyses of prestressed concrete(PSC) test beams for inservice inspection of prestressed concrete containments for CANDU nuclear power plants are presented. In the analysis the material nonlinearities of concrete, rebar and prestressing steel are used. To reduce the numerical instability with respect to the used finite element mesh size, the tension stiffening effect has been considered. For concrete, the tensile stress-strain relationship derived from tests is modified and the stress-strain curve of rebar is assumed as a simple bilinear model. The stress-strain curve of prestressing steel is applied as a multilineal curve with the first straight line up to 0.8fpu. To prove the validity of the applied material models, the behavior and strength of the PSC test specimens tested to failure have been evaluated. A reasonable agreement between the experimental results and the predictions is obtained. Parametric studies on the tension stiffening effects, the impact of prestressing losses with time, and the compressive strength of concrete have been conducted.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.756-761
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• 1999

The objective of this study is to develop finite element analysis technique to predict the strength reduction of deteriorated reinforced concrete beams and their strengthening capacity. In order to consider the effect of rebar corrosion, a tension stiffening model is proposed and area reduction of rebars due to corrosion is considered. For the analysis of strengthened deteriorated RC beams, one dimensional truss element and an interface element are introduced for models of the strengthening composite and the interface between concrete and composite to simulate delamination or discontinuous behavior at the interface. Then, analyses for deteriorated RC beams strengthened with glass fiber reinforced epoxy panel (GFREP) are carried out to predict both flexural failure and plate-end delamination failure. Finally, analysis results are verified with experimental results.

• Computers and Concrete
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• v.3 no.1
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• pp.65-77
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• 2006

This study reports the details of the finite element analysis of eleven shear critical partially prestressed concrete T-beams having steel fibers over partial or full depth. Prestressed concrete T-beams having a shear span to depth ratio of 2.65 and 1.59 and failing in the shear have been analyzed using 'ANSYS'. The 'ANSYS' model accounts for the nonlinear phenomenon, such as, bond-slip of longitudinal reinforcements, post-cracking tensile stiffness of the concrete, stress transfer across the cracked blocks of the concrete and load sustenance through the bridging of steel fibers at crack interface. The concrete is modeled using 'SOLID65'-eight-node brick element, which is capable of simulating the cracking and crushing behavior of brittle materials. The reinforcements such as deformed bars, prestressing wires and steel fibers have been modeled discretely using 'LINK8' - 3D spar element. The slip between the reinforcement (rebar, fibers) and the concrete has been modeled using a 'COMBIN39'-non-linear spring element connecting the nodes of the 'LINK8' element representing the reinforcement and nodes of the 'SOLID65' elements representing the concrete. The 'ANSYS' model correctly predicted the diagonal tension failure and shear compression failure of prestressed concrete beams observed in the experiment. The capability of the model to capture the critical crack regions, loads and deflections for various types of shear failures in prestressed concrete beam has been illustrated.

• Journal of the Korea Concrete Institute
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• v.22 no.6
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• pp.753-760
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• 2010

Ultra high performance concrete (UHPC), is characterized by its high compressive strength and advanced tensile behavior that is much superior to those of conventional concrete. In order to apply this new material in practice, the bond characteristics of UHPC were evaluated in this study. Pull-out tests between UHPC and deformed steel rebar were carried out according to the modified RILEM test method, and were verified by finite element analysis. From the test results showed that UHPC presents 5 to 10 times higher bond strength compared to normal strength concrete, this study suggested remarkably reduced development length and concrete cover comparing to existing specifications. The test results of 700 MPa high strength steel rebar demonstrated the applicability of high strength steel to UHPC. In addition, the transfer length measurements of seven-wire strand in UHPC specimens indicated that the transfer length limit set by the current design code is very conservative for UHPC.

• Journal of the Korean Society of Safety
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• v.34 no.2
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• pp.40-47
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• 2019

The Half-depth precast deck is a structural system that utilizes pre-cast panels pre-built at the factory as formwork at the construction stage and as a major structural member at the same time after completion. These systems have joints between segments, and the detail and performance of the joints are factors that have a very large impact on the quality, such as the constructability and durability of the bridge decks. In this study, strength performance evaluation was performed for improved joints using connecting rebar by experimental method. Static loading tests were conducted on the test specimen with improved joint, those with existing joint and those without joint. The test results of the specimens were compared to each other, and the flexural strength required by the design was compared. The flexural strength required in the design was presented by finite element analysis. It has been shown that the flexural strength of the specimens with joints were more than twice that required by the design. But the flexural strength of the specimen with existing joint was about 84% of that without joint. The flexural strength of the specimen with improved joints was a nearly similar degree of that compared to the specimen without joint. And a comparison of the moment-deflection relationship curves of the two specimens also shows a very similar flexural behavior. It is confirmed that improved joint has sufficient flexural strength. In addition to strength, the bridge decks require serviceability, such as deflection and cracking, and in particular, fatigue resistance due to repetitive live loads is an important performance factor. Therefore, further verification studies are required.

• Steel and Composite Structures
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• v.37 no.2
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• pp.117-136
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• 2020

Curved steel-concrete composite box girder has been widely adopted in urban overpasses and ramp bridges. In order to investigate its mechanical behavior under complicated and combined bending, shear and torsion load, two large-curvature composite box girders with interior angles of 25° and 45° were tested under static hogging moment. Based on the strain and deflection measurement on critical cross-sections during the static loading test, the failure mode, cracking behavior, load-displacement relationship, and strain distribution in the steel plate and rebar were investigated in detail. The test result showed the large-curvature composite box girders exhibited notable shear lag in the concrete slab and steel girder. Also, the constraint torsion and distortion effect caused the stress measured at the inner side of the composite beam to be notably higher than that of the outer side. The strain distribution in the steel web was approximately linear; therefore, the assumption that the plane section remains plane was approximately validated based on strain measurement at steel web. Furthermore, the full-process non-linear elaborate finite element (FE) models of the two specimens were developed based on commercial FE software MSC.MARC. The modeling scheme and constitutive model were illustrated in detail. Based on the comparison between the FE model and test results, the FE model effectively simulated the failure mode, the load-displacement curve, and the strain development of longitudinal rebar and steel girder with sufficient accuracy. The comparison between the FE model and the test result validated the accuracy of the developed FE model.

• Steel and Composite Structures
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• v.31 no.1
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• pp.53-67
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• 2019

This study presents finite element analysis (FEA) on a Y-type perfobond rib shear connection using Abaqus software. The performance of a shear connection is evaluated by conducting a push-out test. However, in practice, it is inefficient to verify the performance by conducting a push-out test with regard to all design variables pertaining to a shear connector. To overcome this problem, FEA is conducted on various shear connectors to accurately estimate the shear strength of the Y-type perfobond rib shear connection. Previous push-out test results for 14 typical push-out test specimens and those obtained through FEA are compared to analyze the shear behavior including consideration of the design variables. The results show that the developed finite element model successfully reflects the effects of changes in the design variables. In addition, using the developed FEA model, the shear resistance of a stubby Y-type perfobond rib shear connector is evaluated based on the concrete strength and transverse rebar size variables. Then, the existing shear resistance formula is upgraded based on the FEA results.