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

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1992.04a
• /
• pp.65-70
• /
• 1992

This study deals with the finite element analysis of the monotonic behavior of reinforced concrete beams and beam-column joint subassemblages. It is assumed that the behavior of these members can be discribed by a plane stress field. Concrete and reinforcing steel are represented by separate material models which are combined together with a model of the interaction between reinforcing bar and concrete through bond-slip to discribe the behavior of the composite reinforced concrete material. To discribe the concrete behavior, a nonlinear orthotropic model is adopted and the crack is discribed by a system of orthogonal cracks, which are rotating as the principal strain directions are changed. A smeared finite element model based on the fracture mechanics principles are used to overcome the numerical defect according to the finite element mesh size. Finally, correlation studies between analytical and experimental results and several parameter studies are conducted with the objective to estabilish the validity of the proposed model and identify the significance of various effects on the local and global response of reinforced concrete members.

• Structural Engineering and Mechanics
• /
• v.46 no.5
• /
• pp.615-627
• /
• 2013

One of the most common defects in reinforced concrete bridge decks is corrosion of steel reinforcing bars. This invisible defect reduces the deck stiffness and affects the bridge's serviceability. Regular monitoring of the bridge is required to detect and control this type of damage and in turn, minimize repair costs. Because the corrosion is hidden within the deck, this type of damage cannot be easily detected by visual inspection and therefore, an alternative damage detection technique is required. This research develops a non-destructive method for detecting reinforcing bar corrosion. Experimental modal analysis, as a non-destructive testing technique, and finite element (FE) model updating are used in this method. The location and size of corrosion in the reinforcing bars is predicted by creating a finite element model of bridge deck and updating the model characteristics to match the experimental results. The practicality and applicability of the proposed method were evaluated by applying the new technique to a two spans bridge for monitoring steel bar corrosion. It was shown that the proposed method can predict the location and size of reinforcing bars corrosion with reasonable accuracy.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.22 no.1
• /
• pp.199-207
• /
• 2018

Experimental programs were performed to evaluate the flexural performance of fiber reinforced concrete(FRC) beams using a hybrid double-layer arrangement of steel bars and fiber reinforced polymer(FRP) bars or using FRP bars only. A total of seven beam specimens were produced with type of tensile reinforcing bar(CFRP bar, GFRP bar, steel bar) and the poly vinyl alcohol(PVA) fiber mixing ratio(0.5%, 0%) as variable. An analysis method for predicting the flexural behaviors of FRC beams with hybrid arrangement of heterogeneous reinforcing bars through finite element analysis was proposed and verified. In case of the specimens with the double-layer reinforcing bars, the test results showed that the first cracking load of specimen with a double-layer arrangement of steel bars was greater by 26-34% than specimens with a hybrid double-layer arrangement of steel and FRP bars. In maximum flexural strengths, the specimen that used CFRP bars as bottom tensile reinforcing bar showed the greatest strength among the specimens with the double-layer reinforcing bars. When the maximum moment value obtained through experiments was compared with that obtained through analysis, the ratio was 1.2 on average, the standard deviation was 0.085, and the maximum error rate was 22% or less. Based on these results, the finite element analysis model proposed in this study can effectively simulate the actual behavior of the beams with hybrid double-layer reinforcing bars.

• Structural Engineering and Mechanics
• /
• v.5 no.5
• /
• pp.663-677
• /
• 1997

Bond-slip behavior between reinforcement and concrete under push-pull cyclic loadings is numerically investigated based on a reinforcement model proposed in this paper. The equivalent reinforcing steel model considering the bond-slip effect without taking double nodes is derived through the equilibrium at each node of steel and the compatibility condition between steel and concrete. Besides a specific transformation algorithm is composed to transfer the forces and displacements from the nodes of the steel element to the nodes of the concrete element. This model first results in an effective use in the case of complex steel arrangements where the steel elements cross the sides of the concrete elements and second turns the impossibility into a possibility in consideration of the bond-slip effect in three dimensional finite element analysis. Finally, the correlation studies between numerical and experimental results under the continuously repeated large deformation stages demonstrate the validity of developed reinforcing steel model and adopted algorithms.

• Journal of the Korea Concrete Institute
• /
• v.17 no.1 s.85
• /
• pp.43-49
• /
• 2005

In the concrete structures, the magnitude and distribution of the temperature due to the heat of hydration are related to the thermal properties of each component composed of the concrete, the initial temperature, the type of formwork, and the ambient temperature of exposed surfaces. Even though the reinforcing steel bar has completely different thermal properties, it has been excluded. In the thermal analysis on the concrete structures. In this study, finite element analysis was performed on the concrete structures including the reinforcing steel in order to investigate their effect on temperature and stress distribution due to the heat of hydration. As the steel ratio increased, the maximum temperature and the internal-external temperature difference decreased by 32.5% and 10%, respectively. It is clear that the inclusion of reinforcing steel bars on the heat of hydration analysis is indispensable to obtain realistic solutions for the prediction of the maximum temperature and stresses

• Geotechnical Engineering
• /
• v.2 no.3
• /
• pp.51-66
• /
• 1986

The design of fabric reinforced retaining wall structure was discussed in this article. It was confirmed that the reinforced retaining earth wall which was designed by new theoretical formulae developed this time was stable structurally and economically. The plastic fabric filter which was placed in layers behind the facing element reduced the lateral earth pressure on the wall elements in comparison with a conventional retaining earth walls. The reinforcing characteristics of earth wall was governed by the spacing of fabric layers, effective length of fabrics, particle distribution and compaction, and thus it is essential that, in the construction field, the reinforcing strips should be selected in order to develop the maximum friction forces bet.eon soil and fabric filters. The maximum tensile stress developed from the reinforcing strips was appeared at a little far distance from the back of skin element and it was not well agreed with the Rankine's theory but distributed well as a symmetrical shape against the point of the maximum tensile stress. The total length of the different layers should be sufficient so that the tension in the fabric strip could be transferred to the backfill material. Also the total stability of reinforced earth wall should be checked with respect to a failure surface which extended blond the different lathers.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.1
• /
• pp.58-66
• /
• 2022

In this study, to examine the effect of the transverse thermal expansion behavior of FRP reinforcing bars and concrete on the concrete cover thickness, based on 20℃, when the temperature changes from -70℃ to 80℃, the behavior of concrete was studied theoretically and numerically. Theoretical elastic analysis and nonlinear finite element analysis were performed on FRP reinforced concrete with different diameters and cover thicknesses of FRP reinforcement. As a result, at a negative temperature difference, concrete was compressed, and the theoretical strain result and the finite element result were similar, but at a positive temperature difference, tensile stress and further cracks occurred in the concrete, which was 1.2 to 1.4 times larger than the theoretical result. The ratio of the diameter of the FRP reinforcing bar to the thickness of the concrete cover (c/db) is closely related to the occurrence of cracks. Since the transverse thermal expansion coefficient of FRP reinforcing bars is three times greater than that of concrete, it is necessary to consider this in design.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1991.10a
• /
• pp.17-22
• /
• 1991

An accurate and efficient analytical model describing the bond effect between reinforcing steel and concrete without taking the double nodes is presented. To increase the efficiency of the solution and reduce the number of degrees of freedom, the reinforcing bar elements are considered to be embedded in the connote elements. Relative douses of freedom accounting for the relative slip between reinforcing steel and concrete are condensed out during the stiffness formation phase. However, these degrees of freedom Can be taken into account explicitly by solving the constructed global equilibrium equation for each reinforcing steel. The usefulness of proposed model is established through the comparison with the experimental data subjected on push and push-pull loadings.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.11a
• /
• pp.629-632
• /
• 2006

The various rib geometry of hybrid fiber reinforced polymer (FRP) reinforcing bars were analyzed by finite element method. From the analysis result, two types of hybrid FRP reinforcing bars such as spiral and cross type with the same dimension of rib geometry were fabricated in this study. To evaluate the bond properties of them, direct pull-out test was performed. All testing procedures including specimens preparation, set-up of test equipments and measuring devices were made in accordance with the recommendations of CSA Standard S806-02. From the test results, it was found that cross type hybrid FRP reinforcing bars showed the highest bond strength than that of the others due to the higher relative rib area.