• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.342-347
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• 2004

Excavation nearby the existing structures is being performed vigorously to get the greatest use of land along with fast economic growth in the downtown area. The application of soil nailing system gradually increases because of an advantage of soil nailing system adjacently constructed in the existing structures. In this study, friction resistance by pull-out is considered as main resistance except resistance formed by flexural rigidity of nail observing that resistance of flexural rigidity is about $0{\sim}15\;%$ of whole safety factor according to degree of flexural rigidity in general soil nail wall and application of geosynthetic fiber soil nailing system is evaluated through laboratory tensile strength test and field pull-out test.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 봄 학술발표회 논문집
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• pp.137-144
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• 1999

Recently a removable soil nail is demanded due to problems beyond of economical and engineering purpose. In this study removable soil nails are developed and field pull-out tests are carried out 16 times in order to analysis pull-out characteristics of the removable soil nail. For the spacing and the installed position of fixed socket, the length of the soil nail, and W/C ratio of cement grout in the removable soil nail, pull-out characteristics of pull-out tests are analyzed. From the pull-out characteristics of removable soil nails, it is found that the spacing of fixed socket and W/C ratio of cement grout are important design parameters.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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• pp.387-394
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• 2000

In the present study, laboratory pull-out tests with screw anchors are carried out to investigate behavior characteristics of underground structures applied uplift seepage forces. Small scaled pull-out tests in sand were conducted under saturated condition. And then, it was observed that the upward displacement as well as the pullout load varied with spacing of the anchor. Also, analyses have been performed with the aim of pointing out the effects of various parameters on the group effect of the screw anchors.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.335-340
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• 2001

Recently in abroad, structural synthetic fiber developed, has been studied extensively as a substitute for steel fiber due to its properties such as corrosion-resistance, low density, good pumping, and in-place safety, etc. In this study, we conducted pull-out test, for seven different geometries of structural synthetic fibers and obtained optimum geometry for structural synthetic fiber which fully utilizes matrix anchoring without revealing fiber fracturing. According to pull-out test results, it was found that crimped type structural synthetic fiber give significant improvement in the interface toughness(roll-out enemy) and pull-out load.

• 한국표면공학회지
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• 제34권2호
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• pp.142-150
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• 2001

Due to naturally formed copper oxides, the adhesion strength between copper and epoxy resin is often very poor. To improve the adhesion strength between copper and epoxy resin, Cu-based leadframe sheets were oxidized in a brown-oxide forming solution. Then the effect of brown-oxide formation on the adhesion strength of leadframe to epoxy molding compound (EMC) was studied using pull-out specimens. After the pull-out test, fracture surfaces were analyzed using SEM, AES and EDS to determine failure path. The results showed that the failure path lay over inside the CuO and inside the EMC irrespective of the pull strength.

• 대한토목학회논문집
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• 제29권6C호
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• pp.313-319
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• 2009

본 연구에서는 접이식 웨지를 장착한 강관네일의 거동 특성 평가를 위해 현장인발시험 및 3차원 수치해석을 수행하였다. 접이식 웨지를 장착한 강관네일의 현장인발시험 결과 접이식 웨지가 없는 경우에 비해 약 30% 정도의 인발 저항 증진효과가 있는 것으로 평가되었다. 한편, 강관네일의 합리적인 인발거동 분석을 위해 3차원 수치해석에서는 접이식 웨지가 장착 되지 않은 강관네일의 역해석을 통하여 현장 인발거동과 일치하는 네일과 지반사이의 마찰 특성을 평가하고, 이를 접이식 웨지가 장착된 강관네일의 해석에 도입하여 그 거동을 분석하였다. 시행착오를 통한 역해석 결과 그라우트와 지반 사이의 마찰계수(${\mu}$)는 약 1.2 정도가 발휘되는 것으로 평가되었으며, 강관네일의 극한인발저항력은 $$T_L{\sim_=}32$$ tonf으로 접이식 웨지가 장착되지 않은 네일의 $$T_L{\sim_=}24$$ tonf 보다 약 33% 증가하는 것으로 평가되어 현장인발시험결과와 거의 일치하는 것으로 나타났다.

• Structural Engineering and Mechanics
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• 제65권5호
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• pp.601-609
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• 2018

Steel bolts are used in the construction industry for a large variety of applications that range from fixing permanent installations to temporary fixtures. In the past much research has been focused on developing destructive testing techniques to estimate their pull-out load carrying capacity with very little attention to develop non-destructive techniques. In this regards the presented research work details the combined use of ultrasonic pulse velocity and Schmidt hammer tests to identify anchor bolts with faculty installation and to estimate their pull-out strength by relating it to the Schmidt hammer rebound value. From experimentation, it was observed that the load capacity of bolt depends on its embedment length, diameter, bond quality/concrete strength and alignment. Ultrasonic pulse velocity test is used to judge the quality of bond of embedded anchor bolt by relating the increase in ultrasonic pulse transit time to the presence of internal pours and cracks in the vicinity of steel bolt and the surrounding concrete. This information combined with the Schmidt hammer rebound number, R, can be used to accurately identify defective bolts which resulted in lower pull-out strength. 12 mm diameter bolts with embedment length of 70 mm and 50 mm were investigated using constant strength concrete. Pull-out load capacity versus the Schmidt hammer rebound number for each embedment length is presented.

• International Journal of Concrete Structures and Materials
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• 제11권1호
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• pp.69-84
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• 2017

This paper presents results of an experimental investigation on the behaviour of bond between external glass fibre reinforced polymer reinforcement and concrete exposed to three different environmental conditions, namely, temperature cycles, wet-dry cycles and outdoor environment separately for extended durations. Single shear tests (pull-out test) were conducted to investigate bond strengths (pull-out strengths) of control (unexposed) and exposed specimens. Effect of the exposure conditions on the compressive strength of concrete were also investigated separately to understand the effect of changing concrete compressive strength on the pull-out strength. Based on the comparison of experimental results of exposed specimens to control specimens in terms of bond strengths, failure modes and strain profiles, the most significant degradation of pull-out strength was observed in specimens exposed to outdoor environment, whereas temperature cycles did not cause any deterioration of strength.

• 한국구조물진단유지관리공학회 논문집
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• 제6권4호
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• pp.201-207
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• 2002

An advanced fiber sheet has been widely used for strengthening of the concrete structures due to its excellent properties such as high strength and light weight. Bond strength is very important in strengthening the concrete structures using an advanced fiber sheet. This research examines the bond behavior between fiber sheet and concrete, investigates the bond strength by the direct pull-out test and the tensile-shear test. To obtain the tensile-shear strength a double-face shear type bond test is conducted. The primary test variables are the types of concrete surface roughness (disk-grinding/chipping) and retrofitting methods (bonding/injection). Thirty specimens were tested to evaluate the bond strength. It is shown that the average bond strength between fiber sheet and concrete by the direct pull-out test and the tensile-shear test is $22.3{\sim}23.1kgf/cm^2$ $17.92{\sim}19.75kgf/cm^2$, respectively.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.1120-1131
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• 2010

In this thesis the model tests were performed to the horizontal pull-out characteristics of a suction pile subjected to a pull in sands. For this model tests, soil conditions ($D_r$=65), three pile diameters (D=100, 150, 200mm) and five loading points (h/L=0, 0.25, 0.5, 0.75, 1) were changed. And the experimental results were also compared with those by the theoretical methods. The results by the experimental and theoretical analysis are as follows. The ultimate horizontal pull-out resistance by the model test increased as the loading point (h/L) moved downwards from the pile top, and the maximum value reached at the h/L=0.75. The theoretical ultimate horizontal pull-out resistance by Broms(1964) and Hong(1984) agreed well with that by the model test at h/L=0 and 0.25, but their results overestimated the experimental result at lower part of pile and the differences between the theoretical and experimental results were of great. While the horizontal loading applied at the upper part of pile, the pile moved to the horizontal direction with rotating clockwise. As the loading point moved downwards from the pile top, the rotating angle of pile was smaller.