• The Journal of Engineering Geology
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• v.15 no.1
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• pp.77-86
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• 2005

CFRD(Concrete Faced Rockfill Dam) is in widespread use because this type of dam has superior characteristics in structural, material aspects comparing with earth cored rockfill dam. On this paper, up-to-date re-searches and techniques are summed up to be available for future needs in design and construction of CFRD. For example, such items as embankment using weak rock, experience of sand-gravel fill CFRD, connecting slab applied between plinth and face slab, raising experience of old dm, inverse filtration problem, environmental friendly zone, thickness and reinforcing of face slab, alluvial foundation treatment, and curb element method, are summarized for understanding of related engineers.

• Magazine of the Korea Concrete Institute
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• v.9 no.2
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• pp.133-144
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• 1997

Concrete plasticity models fol the analysis of reinforced concrete members in plane stress are studied. The proposed plasticity model for reinforced concrete provides a unified approach combining plasticity theory and damage models. It addresses strength mhancement under rnultiaxial compression. and tensile cracking damage. The model uses multiple failure criteria for compressive crushing and tensile cracking. For tensile cracking behavior. rotating-crack and fixed-crack plasticity models are compared. As crushing failure criterion, the Drucker-Prager and the von Mises models are used for comparison. The model uses now and existing damnge models fbr tension softening, tension stiffening. and compression softening dup to tensilt. cracking. Finite element analyses using the unified method are compatxd with existing rxpcrimcntal r.esults. To vei.ify the proposcd crushing and cracking plasticity models, the experiments have load capacities govc11.nc.d either by compressive crushing of'concrete or by yi~lding of' reinforcing steel.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.249-252
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• 2008

A study for the nonlinear analysis method of RC(Reinforced Concrete) beams with unbonded prestressing CFRP plate is presented. The cross-section of RC beam element is idealized as an assemblage of concrete and reinforcing steel fibers in order to account for varied material properties within the cross-section of the element. The unbonded CFRP plate is modeled as a series of the CFRP plate segments each of which is linked to the RC beam element, but slips without any resistance to simulate the unbonded behavior of the CFRP plate. The stress of each CFRP plate segment is redistributed iteratively using the force equilibrium relationship at each common node until it reaches at the same stress level. To evaluate the validity of the proposed analysis method, the results of ultimate analysis of the reinforced concrete beams with unbonded prestressing CFRP plates are compared with the experimental results obtained from other investigators. The proposed analysis method is found to predict ultimate behaviors of these beams fairly well.

• Computers and Concrete
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• v.22 no.2
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• pp.167-182
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• 2018

The modeling of loss of bond between reinforcing bars (rebars) and concrete due to corrosion is useful in studying the behavior and prediction of residual load bearing capacity of corroded reinforced concrete (RC) members. In the present work, first the possibility of using different methods to simulate the rebars-concrete bonding, which is used in three-dimensional (3D) finite element (FE) modeling of corroded RC beams, was explored. The cohesive surface interaction method was found to be most suitable for simulating the bond between rebars and concrete. Secondly, using the cohesive surface interaction approach, the 3D FE modeling of the behavior of non-corroded and corroded RC beams was carried out in an ABAQUS environment. Experimental data, reported in literature, were used to validate the models. Then using the developed models, a parametric study was conducted to examine the effects of some parameters, such as degree and location of the corrosion, on the behavior and residual capacity of the corroded beams. The results obtained from the parametric analysis using the developed model showed that corrosion in top compression rebars has very small effect on the flexural behaviors of beams with small flexural reinforcement ratio that is less than the maximum ratio specified in ACI-318-14 (singly RC beam). In addition, the reduction of steel yield strength in tension reinforcement due to corrosion is the main source of reducing the load bearing capacity of corroded RC beams. The most critical corrosion-induced damage is the complete loss of bond between rebars and the concrete as it causes sudden failure and the beam acts as un-reinforced beam.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.6
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• pp.258-263
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• 2020

Silicon carbide (SiC) fibers mainly fabricated from polycarbosilane, a ceramic precursor, are applied as reinforcing materials for ceramic matrix composites (CMCs) because of their high temperature oxidation resistance, tensile strength, and light weight. In this study, continuous SiC fibers used to fabricate rope-type flexible heating elements capable of generating high-temperature heat (> 650℃). For high-efficiency heating elements, the resistance of SiC fiber rope was measured by 2-point probe method according to the cross-sectional area and length. In addition, the fabrication conditions of rope-type SiC fiber heating elements were optimized by controlling the oxygen impurities and the size of crystal grains present in the amorphous SiC fiber. As a result, the SiC fiber heating element having a resistance range of about 100~200 Ω exhibited an excellent power consumption efficiency of 1.5 times compared to that of the carbon fiber heating element.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.3
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• pp.129-139
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• 2024

In this study, the SBC system, a new mechanical joint method, was developed to improve the constructability of precast concrete (PC) beam-column connections. The reliability of the finite element analysis model was verified through the comparison of experimental results and FEM analysis results. Recently, the intermediate moment frame, a seismic force resistance system, has served as a ramen structure that resists seismic force through beams and columns and has few load-bearing walls, so it is increasingly being applied to PC warehouses and PC factories with high loads and long spans. However, looking at the existing PC beam-column anchorage details, the wire, strand, and lower main bar are overlapped with the anchorage rebar at the end, so they do not satisfy the joint and anchorage requirements for reinforcing bars (KDS 41 17 00 9.3). Therefore, a mechanical joint method (SBC) was developed to meet the relevant standards and improve constructability. Tensile and bending experiments were conducted to examine structural performance, and a finite element analysis model was created. The load-displacement curve and failure pattern confirmed that both the experimental and analysis results were similar, and it was verified that a reliable finite element analysis model was built. In addition, bending tests showed that the larger the thickness of the bolt joint surface of the SBC, the better its structural performance. It was also determined that the system could improve energy dissipation ability and ductility through buckling and yielding occurring in the SBC.

• Journal of the Korea Concrete Institute
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• v.20 no.1
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• pp.3-11
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• 2008

An experimental investigation was conducted with half-scale representations of the reinforced concrete shear walls with the opening subjected to cyclic loads. Specimens were half scale representations of a one-story wall in the apartment built in 1980. The area ratio of the opening section, as well as the size and critical section of coupling slabs, were decided based on results from a previous researches. The test result of WS-0.23 specimen, which has artificial damages to install the opening, the strength of the wall decreased due to the opening. It is apparent that influence of cutting reinforcing bars and decrease of effective section area lead to early first yield of the reinforcing bars before the allowable limit of drift ratio of the shear walls was reached. Therefore, proper reinforcing method is needed to prevent this. The decrease of strength of the shear walls by installation of openings shows a great deal of difference compared to previous researches. This is because flexural capacity of the slabs is working as coupling elements for the shear walls. The critical section of coupling slabs that works as coupling elements for shear walls was a little different from the results of previous researches.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.2
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• pp.38-46
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• 2014

Effects of various parameters on bond property between reinforcing bar and concrete are investigated in many researchers, and various study is on going to improve the bond strength. Properties of interface between reinforcement and concrete is important role in bond property. This study analyzed the interfacial bond mechanism between deformed bar and concrete by finite element analysis (FEA) to evaluate the effect of rib shape. The FEA model in this study is simplified 2D plane stress model. The variables of analysis are selected by rib angle, rib height, rib spacing and relative rib area. From the results of analysis, reinforcing bars with rib angle $30{\sim}60^{\circ}$ showed better bond strength than the others. Bond strength ratio following to the rib height is proportionally increased up to the $0.12d_b$, but rib spacing has little effect on bond strength. The results also indicated that relative rib area can be efficiently represented the properties of deformed shape in reinforcing bars, and zigzagged rib height shape showed excellent bond strength increase.

• Journal of the Korea Concrete Institute
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• v.28 no.4
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• pp.473-480
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• 2016

The purpose of this study is to provide analytical method to reasonably evaluate the complicated failure behaviors of shear friction of reinforced concrete shear wall specimens using grade 500 MPa high-strength bars. A total of 16 test specimens with a variety of variables such as aspect ratio, friction coefficient of interface in construction joint, reinforcement details, reinforcement ratio in each direction, material properties were selected and the analysis was performed by using a non-linear finite element analysis program (RCAHEST) applying the modified shear friction constitutive equation in interface based on the concrete design code (KCI, 2012) and CEB-FIP Model code 2010. The mean and coefficient of variation for maximum load from the experiment and analysis results was predicted 1.04 and 17% respectively and properly evaluated failure mode and overall behavior characteristic until failure occur. Based on the results, the analysis program that was applied modified shear friction constitutive equation is judged as having a relatively high reliability for the analysis results.

• Composites Research
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• v.34 no.1
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• pp.8-15
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• 2021

In the shipbuilding and marine industry, as a technology for reducing the weight of parts to reduce energy and improve operational efficiency of ships is required, a method of applying fibers-reinforced composites which is high-strength lightweight materials, as part materials can be considered. In this study, the possibility of applying fibers-reinforced composites to the pipe support clamps was evaluated to reduce the weight of LNGC. The fibers-reinforced composites were manufactured using carbon fibers and glass fibers as reinforcing fibers. Through the computer simulation program, the properties of the reinforcing materials and the matrix materials of the composites were inversely calculated, and the performance prediction was performed according to the change in the properties of each fiber lamination pattern. In addition, the structural analysis of the clamps according to the thickness of the composites was performed through the finite element analysis program. As a result of the study, it was confirmed that attention is needed in selecting the thickness when applying the fibers-reinforced composites of the clamp for weight reduction. It is considered that it will be easy to change the shape of the structure and change the structure for weight reduction in future supplementary design.