• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.393-396
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• 2008

The purpose of this paper is to find out quantitatively the relationship between the surface shape and the mechanical properties of corroded reinforcement. Three-dimensional measurements were carried out on the surface shape of variously corroded reinforcements and parameters expressing the characteristics of the shape, which included the maximum decrement of sectional area of reinforcement, its distribution along the axis. It was investigated that which parameters could correspond to the mechanical properties of corroded reinforcement and it was confirmed that the maximum decrement of sectional area of reinforcement could express the mechanical properties most appropriately. Finally, this paper proposes a constitutive model of corroded reinforcement for analyzing the structural behavior of reinforced concrete structures considering the localized corrosion of by finite element method.

• Restorative Dentistry and Endodontics
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• v.25 no.3
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• pp.371-380
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• 2000

The effect of fiber reinforcing materials on the fracture strength of composite resin was evaluated. Each ten composite resin bars reinforced by glassfiber[Fiber-Splint ML$^{(R)}$(Polydentia SA, Switzerland)], polyethylene fiber [Ribbond$^{(R)}$(Ribbond Inc., U.S.A.)] and polyaramid fiber[Kevlar$^{(R)}$(DuPont, U.S.A.)] were loaded under the 3-point compression technique. Another ten pure composite resin bars without reinforcement were used as a control group. Then mean fracture strength and standard deviation were calculated and a ANOVA and Scheffe test were used in statistics. The results were as follows: 1. Kevlar group showed the highest fracture strength as 175.5MPa (p<0.05). Fiber-Splint ML group showed the lowest fracture strength as 112.7MPa. 2. The mean value of fracture strength in Ribbond group was 136.4MPa, and that of unterated control group was 143.6MPa. No difference was found between the two groups. 3. Ribbond and Kevlar reinforcement groups showed a catastrophic failure, where complete separation of pieces occurs to a unseparated fracture pattern. The use of Kevlar reinforcement fibers with composite resin showed significant increase in the average load failure and the presence of the fibers did prevent the catastrophic crack propagation present in the unreinforced samples. The use of Ribbond reinforcement fibers with composite resin showed no significant increase in the average load failure. However, the presence of the fibers did prevent the catastrophic crack propagation. Because high strength of glassfiber are rapidly degraded on exposure to moisture and humidity. The use of Fiber-Splint ML reinforcement fibers with composite resin showed significant decrease in the average load failure and displayed catastrophic fractures.

• The Journal of Engineering Geology
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• v.17 no.1 s.50
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• pp.115-123
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• 2007

Recently, accelerating population and advanced economy result in extending old freeways and constructing new freeways. To make a good freeway shape, tunnel constructions are also rapidly increasing. Therefore, a possibility of a collapse during a tunnel excavation is getting higher in a proportionate manner. Especially, tunnel excavation has increased in poor geological condition in order to maintain good alignment of road and the collapse of tunnel has often happened without reinforcement method. This research paper will analyze for ms and causes of the collapses for different geological conditions and applied reinforcement solutions by investigating typical collapse sites during highway tunnel constructions.

• Earthquakes and Structures
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• v.9 no.4
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• pp.699-718
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• 2015

The effect of reinforcing concrete members with high strength steel bars with yield strength up to 600 MPa on the overall seismic behavior of concrete moment frames was studied experimentally and numerically. Three geometrically identical plane frame models with two bays and two stories, where one frame model was reinforced with hot rolled bars (HRB) with a nominal yield strength of 335 MPa and the other two by high strength steel bars with a nominal yield strength of 600 MPa, were tested under simulated earthquake action considering different axial load ratios to investigate the hysteretic behavior, ductility, strength and stiffness degradation, energy dissipation and plastic deformation characteristics. Test results indicate that utilizing high strength reinforcement can improve the structural resilience, reduce residual deformation and achieve favorable distribution pattern of plastic hinges on beams and columns. The frame models reinforced with normal and high strength steel bars have comparable overall deformation capacity. Compared with the frame model subjected to a low axial load ratio, the ones under a higher axial load ratio exhibit more plump hysteretic loops. The proved reliable finite element analysis software DIANA was used for the numerical simulation of the tests. The analytical results agree well with the experimental results.

• Journal of the Korean Geotechnical Society
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• v.29 no.8
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• pp.27-36
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• 2013

LEM (Limit Equilibrium Method) based programs are commonly used for the designs of soil nailing as a slope reinforcement. However, there is a drawback that the interaction between ground and soil nailing is not properly reflected in those programs, which needs to be solved. For economical constructions and designs, research is also required on the support pattern of soil nailing. In this study, therefore, reinforcement effects of soil nailing were compared and analyzed by performing finite difference analyses which could properly consider the interaction between ground and soil nailing. As a result, when the angle from slope to nail is $90^{\circ}$, failure slip surface becomes the largest and thus the factor of safety becomes maximum.

• Computers and Concrete
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• v.20 no.4
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• pp.483-490
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• 2017

This paper studies on the behavior of reinforced concrete (RC) pipes used in basic sanitation in the conduction of storm water and sanitary sewer. Pipes with 800 mm and 1200 mm in diameter were analyzed. The 800 mm pipes were built with simple reinforcement and the 1200 mm pipes with double reinforcement. For the two diameters of pipes the presence or absence of the pocket was evaluated, and the denomination of each one is spigot and pocket pipe (SPP) and ogee joint pipe (OJP), respectively. The 3D numerical models reproduce the three-edge-bearing test that provides information about the strength and stiffness of the reinforced concrete pipes. The validation of the computational models was carried out comparing the vertical and horizontal displacements on the springline and crown/invert and it was also evaluated the reinforcement strains and the crack pattern. As a main conclusion, the numerical models represented satisfactorily the behavior of the pipes and can be used in future studies in parametric analysis.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.5
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• pp.79-86
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• 2010

This study was performed to evaluate the flexural behavior of Hybrid fiber sheet (HFC) and Hybrid fiber bar (HFB) strengthened reinforced concrete (RC) beams. According to test results, Hybrid fiber reinforcement strengthened RC beams showed approximately 60 to 200% higher reinforcing effects than that of un-reinforced specimens. In addition, the reinforced beams showed the ideal failure pattern, which is failed presenting the ductile behavior after yielding of the reinforcing bar. More specifically, in the case of HFB reinforced RC beams, the difference with puttying method was not apparent since HFB beams reinforced using the injection of epoxy and bonding of putty showed the similar failure patterns.

• Geomechanics and Engineering
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• v.32 no.6
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• pp.653-671
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• 2023

In practice, the interference influence caused by adjacent footings of structures on geo-reinforced loose soil has a considerable impact on their behavior. Thus, the goal of this study is to evaluate the behavior of two strip footings in close proximity on both geocell and geogrid reinforced soil with different reinforcement layers. Geocell was made from geogrid material used to compare the performance of cellular and planar reinforcement on the bearing pressure of twin footings. Extensive experimental tests have been performed to attain the optimum embedment depth and vertical distance between reinforcement layers. Particle image velocimetry (PIV) analysis has been conducted to monitor the deformation, tilting and movement of soil particles beneath and between twin footings. Results of tests and PIV technique were verified using finite element modeling (FEM) and the results of both PIV and FEM were used to utilize failure mechanisms and influenced shear strain around the loading region. The results show that the performance of twin footings on geocell-reinforced sand at allowable and ultimate settlement ranges are almost 4% and 25% greater than the same twin footings on the same geogrid-reinforced sand, respectively. By increasing the distance between twin footings, soil particle displacements become smaller than the settlement of the foundations.

• Journal of the Korean Geotechnical Society
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• v.25 no.12
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• pp.131-142
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• 2009

Geosynthetic reinforced soil walls are well recognized alternatives to conventional retaining walls due to many advantages in terms of ease of construction, economy, and aesthetics, among others. In recent years, the use of back-to-back (BTB) geosynthetic reinforced soil walls has been increasing for roadway and railway construction. However, there are insufficient studies concerning the behavior of BTB type geosynthetic reinforced soil walls. In this study a series of finite element analysis were performed for BTB walls with various wall geometry and reinforcement distribution. The results were then analyzed to relate the wall geometry and reinforcement distribution and the performance of BTB walls. Optimum reinforcement pattern was also investigated.

• Advances in nano research
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• v.16 no.4
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• pp.395-412
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• 2024

This article develops a nonclassical size dependent nanoplate model to study the dynamic response of functionally graded carbon nanotube (FGCNT) nanoplates under a moving load. Both nonlocal and microstructure effects are incorporated through the nonlocal strain gradient elasticity theory. To investigate the effect of reinforcement orientation of CNT, four different configurations are studied and analysed. The FGM gradation thorough the thickness direction is simulated using the power law. In the context of the first order shear deformation theory, the dynamic equations of motion and the associated boundary conditions are derived by Hamilton's principle. An analytical solution of the dynamic equations of motion is derived based on the Navier methodology. The proposed model is verified and compared with the available results in the literature and good agreement is found. The numerical results show that the dynamic performance of FGCNT nanoplates could be governed by the reinforcement pattern and volume fraction in addition to the non-classical parameters and the moving load dimensionless parameter. Obtained results are reassuring in design and analysis of nanoplates reinforced with CNTs.