• Computers and Concrete
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• v.34 no.4
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• pp.503-517
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• 2024

This study presents an analysis model to estimate the shear strength of a reinforced concrete (RC) member with corroded tensile reinforcements. The thick-walled cylinder theory was modified to fit the dual potential capacity model to reflect interdependent failure mechanisms, including the degradation effect of bonds in corroded tensile reinforcement. In the proposed model, it is considered that the shear failure of corroded RC members with no proper anchorage detail is primarily dominated by the flexural-bond mechanism, where insufficient bond strength is provided owing to corrosion damage. However, when tensile reinforcements are properly anchored in the end regions using end hooks or mechanical devices, it is assumed that the tied-arch action can be developed as a secondary shear transfer mechanism, even under severe corrosion damage. The proposed model was verified by comparison with shear test results of corroded RC members collected from the literature, and it appeared that the proposed model can estimate their shear strengths with a good level of accuracy, regardless of various anchorage details and corrosion rates in tensile reinforcements.

• Computers and Concrete
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• v.4 no.3
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• pp.221-241
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• 2007

Based on the experiment results, the damage and fracture behavior of concrete at the ages of 1d, 2d, 7d and 28d, in three-point bending and uniaxial tensile tests, were simulated with a finite element program, ABAQUS. The critical stress intensity factor $K_{IC}^s$ and the critical crack tip opening displacement ($CTOD_C$) of concrete were calculated with effective-elastic crack approach for the three-point bending test of grade C30 concrete. Based on the crack band model, a bilinear strain-softening curve was derived to simulate the LOAD-CMOD curves and LOAD-Displacement curves. In numerical analysis of the uniaxial tension test of concrete of grade C40, the damage and fracture mechanics were combined. The smeared cracking model coupling with damaged variable was adopted to evaluate the onset and development of microcracking of uniaxial tensile specimen. The uniaxial tension test was simulated by invoking the damage plastic model which took both damage and plasticity as inner variables with user subroutines. All the numerical simulated results show good agreement with the experimental results.

• Computers and Concrete
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• v.21 no.5
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• pp.547-557
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• 2018

This paper measures the mechanical response of precast pavement joints under moving axle loads using the finite-element method, and the models were validated with results of field tests. In order to increase the ability to use the non-linear FE analysis for design and assessment of precast pavement subjected to moving axle load, this paper investigated the effects of different load transfer between the slabs using the ABAQUS finite-element package to solve the nonlinear explicit model equations. The assembly of the panels using dowels and groove-tongue keys has been studied to assess the efficiency of keyway joint system. Concrete damage plasticity model was used to calculate the effects of permanent damages related to the failure mechanisms. With aggregate interlock as the only load transferring system, Load transfer efficiency (LTE) is not acceptable when the axle load reaches to slab joints. The Finite-element modelling (FEM) results showed that keyway joints significantly reduced tensile stresses developed at the mid-slab. Increasing the thickness of the tongue the LTE was improved but with increasing the height of the tongue the LTE was decreased. Stresses are transferred to the adjacent slab efficiently when dowels are embedded within the model. When the axle load approaches joints, tensile damage occurs sooner than compressive damage, but the damage rate remains constant, then compressive damage increases significantly and become the major form of distress under the dowels.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2D
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• pp.243-248
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• 2008

Moisture damage of asphalt pavements can usually occur because of the loss of adhesion and cohesion between the asphalt binder and aggregate in the asphalt mixture due to presence of water. And this is one of the causes that is effect on the main distress of asphalt pavement. The objective of this study is to find out moisture damage characteristics of asphalt pavement. Effects of this study changes of the material properties and resistance characteristics of moisture damage on the asphalt mixtures under various temperatures and repeated immersion using indirect tensile test and modify Lottman test were evaluated during this study. The asphalt mixtures were produced using straight asphalt binder, SBS modified asphalt binder and aggregates. The material properties (resilient modulus, indirect tensile strength, failure energy and $DCSE_f$) of the asphalt mixtures were generally decreased with increasing to moisture damage caused by the number of repeated immersion. The decrease ratios of material properties by repeated immersion on SBS modified asphalt mixtures were lower than those of straight asphalt mixtures at all three test temperatures. As a conclusion, current criterion for evaluation moisture damage of asphalt mixtures is difficult for using distinction standard because of the limited evaluation criterion with one time immersion and single material property. Based on this research, to evaluate long term moisture damage on asphalt mixtures, material property tests of various kinds with repeated immersion test are considered.

• International Journal of Automotive Technology
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• v.1 no.2
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• pp.71-77
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• 2000

High temperature materials in service are subjected to mechanical damage due to operating load and metallurgical damage due to operating temperature. Therefore, when designing or assessing life of high temperature components, both factors must be considered. In this paper, the effect of tensile hold time on high temperature fatigue crack growth and long term prior thermal aging heat treatment on creep rupture behavior were investigated using STS 316L and STS 316 austenitic stainless steels, which are widely used for high temperature components like in automotive exhaust and piping systems. In high temperature fatigue crack growth tests using STS 316L, as tensile hold time increased, crack growth rate decreased in relatively short tensile hold time region. In long term aged specimens, cavity type microcracks have been observed at the interface of grain boundary and coarsened carbide.

• Journal of Ocean Engineering and Technology
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• v.9 no.1
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• pp.47-56
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• 1995

This study is aimed to have a database of system development for the prediction, monitoring, analyzing, and evaluation of tensile strength and damage characteristics through AE technique for CFRP. Therefore the correlations between impact characteristics (such as impact velocity, impact energy, delamination area etc) and AE signals for CFRP laminates were investigated. And also it were accomplished the evaluation of tensile strength and the investigation on correlation with AE signals for impact damaged specimen of CFRP laminates.

• Journal of Forest and Environmental Science
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• v.26 no.3
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• pp.193-202
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• 2010

To analyze the effects of tree roots on the stability of damage slope, distributional and physical properties of five-year Pinus densiflora roots were investigated. In the composition of roots, the proportion of main root to lateral root was 1 to 9 in slope condition. Root tensile force was increased in accordance with increased proportion to diameter of Pinus densiflora roots. However, tensile strength was decreased in proportion to diameter of roots. Root shear strength showed that soil containing Pinus densiflora roots was higher than that of non-treated soils. This result shows that Pinus densiflora roots significantly stabilize the surface-soil rather than sub-soil in damage slopes.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.11c
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• pp.105-116
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• 1999

The Inchon International Airport site was formed by reclaimed soil from the sea. The average thickness of soft soil Is about 5 m and most of soft soils are normally consolidated or slightly over consolidated. There are many box culverts which are being constructed under the runways in the airfield. Sometimes, differential settlement can be occurred in the adjacent of box culvert or underground structures at the top layer of runway Soil compaction at very near to the structure is not easy all the time. Thus, one layer of geogrid was placed at the bottom of lean concrete layer for the concrete paved runway and at the middle of cement stabilized sub-base course layer for the asphalt paved runway. The length of geogrid reinforcement is 5m from the end of box culvert for both sides. The extended length of geogrid was 2m from the end of backfill soil in the box culvert. The tensile strength tests of geogrid were conducted for make sure the chemical compatibility with cement treated sub-base material. The location of geogrid placement for the concrete paved runway was evaluated. The construction damage to the geogrid could be occurred. Because the cement treated sub-base layer or lean concrete was spread by the finisher. The magnitude of tensile strength reduction was 1.16%~1.90% due to the construction damage and the ultimate tensile strength is maintained with the specification required. Total area of geogrid placement in this project is about 50,000 $m^2$.

• Journal of Korean Society for Quality Management
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• v.48 no.2
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• pp.257-267
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• 2020

Purpose: The purpose of this study is to define guideline for fiber-glass-resin-putty repairing method for submarine GFRP by comparing structural strength between normal GFRP and putty repaired GFRP. Methods: GFRP specimen tensile and flexural tests are conducted in accordance with ASTM D3039/3039M-17 and ASTM D790 Procedure A. The collected data was analysed whether satisfies its structural strength criteria. Furthermore, It is analysed to find dominant reason of structural strength changes. Results: The result of the study is as follows; flexural strength of GFRP is satisfied strength criteria for all test cases, but tensile strength is not satisfied its criteria for some cases which over 2 mm depth of surface damage. Conclusion: The fiberglass-resin-putty repairing method should be applied to under 2 mm depth of damage which is not affecting to roving fiber layer destruction in GREP laminate.

• Journal of the Korean Society of Clothing and Textiles
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• v.22 no.2
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• pp.224-232
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• 1998

Protease is mixtured in detergent to remove protein-soil easily. It must not act on the any fiber except protein-soil during laundry. So the purpose of this study is to investigate how protease is affect the fiber, particulary the protein-fiber. For this purpose, silk, wool and nylon are selected as samples, and the extent of the damage was estimated as tensile strength and surface condition (that is fibrillation). The results are as follows. The tensile strength of fiber treated with protease were lowered at enzyme concentration 0.1%, temperature 4$0^{\circ}C$ , and, as washing time was longer, it was lowered more. And it was showed that the surface of fibers were fiblliated by protease during washing. From this results, it was found that protease damaged protein-fiber. The damage of silk was the largest of all, and wool was less damaged than silk, because it has the scale (cuticle) on the outside. Additionary, an influence of surfactant on damage of fiber was little about three fibers, but, the fibers were damaged more by the binary nonionic-surfactant and protease mixture than by protease only.