• Journal of the Korea Institute of Building Construction
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• v.18 no.1
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• pp.17-24
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• 2018

The pullout test, a nondestructive testing(NDT), for pre-installed inserts is perhaps the most widely used technique to estimate the in-situ compressive strength of concrete. It measures the force needed to pullout a standardized metal insert embedded into concrete members. The pullout test was certified by the American Society for Testing and Materials(ASTM) and Canadian Standards Association(CSA) as a reliable method for determining the strength of concrete in concrete structures under construction. To easily estimate the strength of ultra-high-strength concrete, a simplified pullout tester, primarily composed of a standard 12mm bolt with a groove on the shaft as a break-off bolt, an insert nut, and a hydraulic oil pump without a load cell, was proposed. Four wall and two slab specimens were tested for two levels of concrete strength, 80MPa and 100MPa, using a simplified pullout tester with a load cell to verify the advantages of the pullout test and simplified pullout test. The compressive strength of concrete, pullout load, and the rupture of the break-off bolt were measured 11 times, day 1 to 7, 14, 21, 28, and 90. The correlation of the pullout load and the compressive strength of each specimen show a higher degree of reliability. Therefore, a simplified pullout test can be used to evaluate the in-place strength of ultra-high-strength concrete in structures. The prediction equation for the groove diameter of the break-off bolt(y) with the concrete strength(x) was proposed as y=0.0184x+5.4. The results described in this research confirm the simplified pullout's utility and potential for low cost, simplicity, and convenience.

• Ocean Systems Engineering
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• v.3 no.2
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• pp.79-95
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• 2013

Suction anchors are widely adopted in mooring systems. However there are still challenges in predicting the failure mode and ultimate pullout capacity of the anchor. Previously published methods for predicting the inclined pullout capacity of suction anchors are mainly based on experimental data or the FEM analysis. In the present work, an analytical method that is capable of predicting the failure mode and ultimate pullout capacity of the suction anchor in clay under inclined loading is developed. This method is based on a rational mechanical model for suction anchors and the knowledge of the mechanism that the anchor fails in seabed soils. In order to examine the analytical model, the failure angle and pullout capacity of suction anchors from FEM simulation, numerical solution and laboratory tests in uniform and linear cohesive soils are employed to compare with the theoretical predictions and the agreement is satisfactory. An analytical method that can evaluate the optimal position of the attachment point is also proposed in the present study. The present work proves that the failure mode and pullout capacity of suction anchors can be reasonably determined by the developed analytical method.

• Journal of the Korean Geotechnical Society
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• v.30 no.1
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• pp.5-16
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• 2014

This paper presents the results of an investigation into the pullout characteristics of screw anchor pile using field pullout tests. A series of field pullout tests were performed on screw anchor piles with different geometric characteristics such as shaft and screw diameters. The results indicated that screw anchor piles exhibited significantly higher pullout capacities compared with the same diameter piles without screw. Also observed is that the set-up effect and the grouting significantly increase pullout capacities, although the magnitude of the increase depends on the ground condition. In addition the applicability of prediction methods for helical pile pullout capacity to screw anchor piles was also examined. The results are presented in such a way that the pullout characteristics of screw anchor piles with different installation conditions can be identified. Practical implications of the findings are discussed.

• Advances in concrete construction
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• v.14 no.5
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• pp.299-307
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• 2022

Cement-based matrixes have low tensile strength and negligible ductility. Adding fibres to these matrixes will improve their mechanical properties and make these composites suitable for structural applications. Post-cracking tensile strength of steel fibers-reinforced cementitious composite materials is directly related to the number of transverse fibers passing through the crack width and the pulling-out behavior of each of the fibers. Therefore, the exact recognition of the pullout behavior of single fibers is necessary to understand the uniaxial tensile and bending behavior of steel fiber-reinforced concrete. In this paper, an experimental study has been carried out on the pullout behavior of 3D (steel fibers with totally two hooks at both ends), 4D (steel fibers with a total of four hooks at both ends), and 5D (steel fibers with totally six hooks at both ends) in which the fibers have been located either perpendicular to the crack width or in an inclined manner. The pullout behavior of the mentioned steel fibers at an inclination angle of 0, 15, 30, 45, and 60 degrees and with embedded lengths of 10, 15, 20, 25, and 30 millimetres is studied in order to explore the simultaneous effect of the inclination angle of the fibers relative to the alongside loading and the embedded length of fibers on the pullout response in each case, including the maximal pullout force, the slip of the maximum point of pullout force, pullout energy, fiber rupture, and concrete matrix spalling. The results showed that the maximum pullout energy in 3D, 4D, and 5D steel fibers with different embedded lengths occurs at 0 to 30° inclination angles. In 5D fibers, maximum pullout energy occurs at a 30° angle with a 25 mm embedded length.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.211-215
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• 1996

This paper presents comparisons of pullout load of concrete with compressive strength of cylinders and cores, pulse velocity, and rebound number. A pullout test, which is a relatively new nondestructive technique, measures with a special tension ram the force required to pullout a specially shaped steel rod whose enlarged end has been cast into a concrete block. In this study 3 concrete mixes(normal strength, high-strength & super-high-strength) were made. From each mix, one 100$\times$70$\times$20 concrete block, 24 cylinders$(\phi10mm)$were casted. Each tests were performed on the concrete blocks at 3, 7, 28, and 91days. The test data shows that the pullout test is superior to the rebond hammer and the pulse velocity measurements on the evaluation of concrete strength. The pullout test is satisfactory for estimating the strength of in situ concrete at both early and late age, and its results can be reproduced with an acceptable degree of accuracy.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.1091-1096
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• 2003

Pullout tests of single headed bars using plain concrete blocks indicate that the embedment depth of $10d_b$ is in general required for the headed bars to develop pullout strength equivalent to 125% of bar yield strength. In this experimental study, test results of multiple headed bars installed in reinforced concrete column sections are presented. Test variables included embedment depth, column main reinforcement ratio, and spacing of column ties. 2D29 bars were pulled out at one time from normal strength concrete. Test results indicated that the embedment depths, column tie spacings, and column main reinforcement ratios all influenced the pullout strengths of the headed bars. When the embedment depth was not sufficient, narrow tie spacings especially resulted in increased pullout strengths of the headed bars. Test results also indicated that the embedment depth of 15㏈ was sufficient for the closely spaced two headed bars (head-to-head spacing =$6d_b$) to develop pullout strength equivalent to 125% of the bar yield strength.

• Geomechanics and Engineering
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• v.5 no.4
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• pp.299-312
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• 2013

The horizontal pullout capacity of a group of two vertical strip plate anchors, placed along the same vertical plane, in a fully cohesive soil has been computed by using the lower bound finite element limit analysis. The effect of spacing between the plate anchors on the magnitude of total group failure load ($P_{uT}$) has been evaluated. An increase of soil cohesion with depth has also been incorporated in the analysis. For a weightless medium, the total pullout resistance of the group becomes maximum corresponding to a certain optimum spacing between the anchor plates which has been found to vary generally between 0.5B and B; where B is the width of the anchor plate. As compared to a single plate anchor, the increase in the pullout resistance for a group of two anchors becomes greater at a higher embedment ratio. The effect of soil unit weight has also been analyzed. It is noted that the interference effect on the pullout resistance increases further with an increase in the unit weight of soil mass.

• Structural Engineering and Mechanics
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• v.51 no.4
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• pp.565-579
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• 2014

The pullout capacity of plate anchors has been studied extensively over the past 40 years. However, very few studies have attempted to calculate the pullout capacity of anchors in sandy slopes. In this paper, three upper bound approaches are used to study the effect of a sloping ground surface and friction angle on pullout capacity and failure of plate anchors. This includes the use of; simple upper bound mechanisms; the block set mechanism approach; and finite element upper bound limit analysis. The aim of this research is to better understand the various failure mechanisms and to develop a simple methodology for estimating the pullout capacity of anchors in sandy slopes.

• Architectural research
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• v.20 no.4
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• pp.129-135
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• 2018

In order to compare the development performance of headed reinforcing bar and straight reinforcing bar in tension for steel fiber reinforced concrete (SFRC), pullout test of specimens with reinforcing bar which was anchored on simple beam perpendicularly was conducted. The experimental variables were steel fiber volume ratio ($V_{Rsf}$), concrete compressive strength, and existence of head. As the result of test, splitting failure of concrete in the development direction of reinforcing bar in most specimens was observed. For development detail of headed reinforcing deformation bar, specimens with 1% $V_{Rsf}$ showed approximately 63%~119% increase in pullout strength compare to specimens with 0% $V_{Rsf}$. Test result shows that SFRC is more effective in increasing pullout strength for headed reinforcing bars than increasing pullout strength of straight bars.

• Journal of the Korea Concrete Institute
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• v.15 no.5
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• pp.643-649
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• 2003

The purpose of this study were evaluated to flexural and bond performance by sectional area and geometry change through bond and flexural test of a structural synthetic fiber. Six deformed structural synthetic fibers were investigated and pullout and flexural test was conducted. Included parameters is three different geometries of fiber and two of fiber sectional area. The test result shows that the cycles and amplitude of structural synthetic fiber increased, pullout load and pullout fracture energy decreased and flexural strength increased, if sectional area is same. The sectional area increased, pullout load and pullout fracture energy increased and flexural strength decreased, if cycles and amplitude of structural synthetic fiber is same. Based on test results, structural performance of the concrete could know that is influence by pullout performance of fiber as well as various factor (fiber number, material properties etc).