• International Journal of Concrete Structures and Materials
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• v.6 no.2
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• pp.101-110
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• 2012

This paper focuses on the finite element (FE) response sensitivity and reliability analyses considering smooth constitutive material models. A reinforced concrete frame is modeled for FE sensitivity analysis followed by direct differentiation method under both static and dynamic load cases. Later, the reliability analysis is performed to predict the seismic behavior of the frame. Displacement sensitivity discontinuities are observed along the pseudo-time axis using non-smooth concrete and reinforcing steel model under quasi-static loading. However, the smooth materials show continuity in response sensitivity at elastic to plastic transition points. The normalized sensitivity results are also used to measure the relative importance of the material parameters on the structural responses. In FE reliability analysis, the influence of smoothness behavior of reinforcing steel is carefully noticed. More efficient and reasonable reliability estimation can be achieved by using smooth material model compare with bilinear material constitutive model.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2435-2438
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• 2011

Steel bar is used for as a reinforcing material in a concrete slab track. Bacuase the steel re-bar could provide passes for current transition, all the cross points of steel re-bars should be insulated by using plastic materials. This is due to the loss of signal intensity of track-circuit. In this study, GFRP bars are adopted in place of the traditional steel reinforcing bars for a concrete slab track to minimize the loss of the signal intensity. In order to evaluate the replacing effect on eletrical characteristic of slab track, measurements of surface resistivity are conducted on steel and GFRP reinforced precast slab tracks. In the results, the GFRP reinforced slab strack shows the higher resistivity than the steel reinforced slab track.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.99-104
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• 2002

This paper presents an analytical prediction of the fatigue damage of reinforced concrete bridge columns subjected to cyclic load. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. In boundary plane at which each member with different thickness is connected, local discontinuity in deformation due to the abrupt change in their stiffness can be taken into account by introducing interface element. The effect of number of load reversals with the same displacement amplitude has been also taken into account to model the reinforcing steel and concrete. The proposed numerical method for fatigue damage of reinforced concrete bridge columns subjected to cyclic load is verified by comparison with reliable experimental results.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.537-540
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• 1999

The primary objective of this study is to make a contribution to the construction of 40~60 story R/C high rise building by developing the reinforcing details which can improve the seismic performance of high-strength (f'c=700kg/$\textrm{cm}^2$, fy=4000, 8000kg/$\textrm{cm}^2$) R/C beam-column joints. And the purpose of this study is to investigate experimentally the effect of load history on the total energy dissipation capacity of reinforced concrete flexural members. The reinforcing details which can make beam plastic hinging zones moved and spreaded from the column face is proposed to insure the ductile behavior of high-strength RC beam-column joints. The intermediate reinforcement which is horizontally anchored by interlinking each intermediate reinforcements is proposed and tested to examine the mechanical performance of proposed details. Main variables are the shape of the intermediate reinforcements and yield strength of rebars. From the test results, the newly proposed intermediate reinforcement details can move and spread the beam plastic hinging zone about 1.0d from the column face.

• Advances in concrete construction
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• v.1 no.2
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• pp.137-149
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• 2013

The first part of this two-part paper discussed some basic considerations on bond strength and its effect on strain localization and plastic deformation capacity of cracked structural concrete, and analytically evaluated the impacts of the hardening behavior of reinforcing steel and concrete quality on the basis of the Tension Chord Model. This second part assesses the impacts of the most frequently encountered construction details of existing concrete structures which may not satisfy current design code requirements: bar ribbing, bar spacing, and concrete cover thickness. It further evaluates the impacts of the additional structure-specific features bar diameter and crack spacing. It concludes with some considerations on the application of the findings in practice and an outlook on future research needs.

• Computers and Concrete
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• v.20 no.3
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• pp.351-360
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• 2017

This paper presents an efficient membrane finite element for the cyclic inelastic response analysis of RC structures under complex plane stress states including shear. The model strikes a balance between accuracy and numerical efficiency to meet the challenge of shear wall simulations in earthquake engineering practice. The concrete material model at the integration points of the finite element is based on damage plasticity with two damage parameters. All reinforcing bars with the same orientation are represented by an embedded orthotropic steel layer based on uniaxial stress-strain relation, so that the dowel and bond-slip effect of the reinforcing steel are presently neglected in the interest of computational efficiency. The model is validated with significant experimental results of the cyclic response of RC panels with uniform stress states.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.6
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• pp.87-92
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• 2007

Strain-stress behavior of soil is of importance in dealing with geo-techniques which relate to bearing capacity, slope stability, earth pressure and many geo-technical problems. So understanding mechanism of the behavior and reinforcing soil to the required state has been an issue for many years. This paper presents the possibility of magnetic force in enhancing shear strength. To analyze the reinforcing effect, triaxial compression tests were performed on two sets of steel-sand mixtures, one of which is influenced by permanent magnet, NdFeB. With magnetic force under 50 kPa confining pressure, maximum shear strengths increased according to steel percentages but under 100 kPa, no significant changes in maximum shear strengths occurred. Therefore the analysis by Mohr's circles indicates that magnetic force converts the shearing characteristics of sand into those of clay.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.538-543
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• 2004

Micropile has been widely used for reinforcing general grounds, improving slope stability and structural foundations. However, a need still exists for evaluating the effects of inclined micropiles on shallow foundations in Korea. In this paper, numerical analyses were presented to evaluate settlement characteristics on shallow foundations reinforced by micropiles and the effects of inclined micropiles under various conditions such as the installation position, installation angle, hardness(diameter), and grouting type. In addition, this paper reports trends of effectiveness and efficiency of using inclined micropiles on shallow foundations under specified conditions.

• Journal of Ocean Engineering and Technology
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• v.20 no.6 s.73
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• pp.1-6
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• 2006

Corrosion of reinforcing steel bars is a major concern for ocean engineers when reinforced concrete structures are exposed to marine environments. Evaluating the degree of corrosion and corrosion-induced defects is extremely necessary to pursue a proper retrofit or rehabilitation plan for reinforced concrete structures. A promising inspection should be carried out for the evaluation, otherwise the retrofit or rehabilitation process would be useless. Nowadays, ultrasonic guided wave-based inspection techniques become quite promising for the inspection, mainly because of their long-range propagation capability and their sensitivity to different types of defects or conditions. Evaluating haw the guided waves response to the different types of defects or conditions is quite challenging and important. This study shows how surface conditions of reinforcing bars and a corrosion-induced defect, separation, affect guided wave propagation in reinforced concrete. Experiments and associated signal analysis show the sensitivity of guided waves to the surface conditions, as well as the amounts of separation at the interface between. concrete and steel bar.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.133-140
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• 2002

The purpose of this study is to investigate the seismic behavior of reinforced concrete bridge piers and to provide the data for developing improved seismic design criteria. A computer program, named RCAHEST(Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. In boundary plane at which each member with different thickness is connected. local discontinuity in deformation due to the abrupt change in their stiffness can be taken into account by introducing interface element. The effect of number of load reversals with the same displacement amplitude has been also taken into account to model the reinforcing steel and concrete. The proposed numerical method for the prediction of seismic behavior for reinforced concrete bridge piers is veri fief by comparison with the reliable experimental results.