Pullout Capacity of Headed Anchors in Prestressed Concrete

Piccinin, Roberto; Ballarini, Roberto; Cattaneo, Sara

doi:10.1061/(asce)em.1943-7889.0000395

Cited by 19 publications

(12 citation statements)

References 19 publications

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“…Simultaneously, the literature survey indicates that analytical models of crack trajectory propagation and the formation of the breakout cone are predominantly based on experimental data and linear elastic crack mechanics [7,13,14]. In recent years, computational methods and numerical analyses using FEM systems, mainly ABAQUS, have been on the rise.…”

Section: Introductionmentioning

confidence: 99%

“…Due to further discrepancies between the theoretical and actual failure modes with respect to the elastic linear fracture mechanics and non-linear fracture mechanics, a number of models have been proposed for the estimation of the load capacity of anchors (the value of the pull-out force) and the extent of failure on the free surface of a base material (e.g., Eligehausen [13], Piccinin [14], Brincker [8]).…”

Section: Introductionmentioning

confidence: 99%

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Three-Dimensional Finite Element Analysis of the Undercut Anchor Group Effect in Rock Cone Failure

et al. 2020

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An objective of this study was to investigate the group effect in rock cone failure occurring in pull-out with the use of 3D finite element analysis. At present, undercut anchors are typically applied as structural fasteners of steel elements in concrete buildings; however, new areas for their use are being explored. The reported study set out to evaluate the use of undercut anchors in special-purpose rock mining, e.g., in mining rescue operations. In such emergencies, mechanical mining may prove impossible, whereas the use of explosives is even prohibited. Although manual methods could be considered, their effectiveness is hard to assess. Prior to considering the use of undercut anchors in mining, several aspects must essentially be determined: The mechanics of cone failure, including the extent of surface failure and the values of the pull-out force of the anchor for a given rock mass relative to the anchor system, the embedment depth, or the rock strength parameters. These factors may be investigated successfully using finite element analysis, the results of which are presented in the study.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Three-Dimensional Finite Element Analysis of the Undercut Anchor Group Effect in Rock Cone Failure

et al. 2020

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“…Several models for predicting the load-carrying capacity of anchorages (the pull-out force) and the size of failure on the free surface of concrete have been proposed, all of which were rooted in the elastic linear fracture mechanics or non-linear fracture mechanics (e.g., Eligehausen [ 4 ], Piccinin [ 16 ], Brincker [ 17 ], Ballarini [ 18 ]). In the study by Kaczmarczyk et al [ 19 ], a computational framework for quasi-static brittle fracture in three-dimensional solids is presented [ 20 , 21 ].…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Rock Failure Cone Size Relative to the Group Effect from a Triangular Anchorage System

et al. 2020

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This study employs the numerical analysis and experimental testing to analyze the fracturing mechanics and the size of rock cones formed in the pull-out of a system of three undercut anchors. The research sets out to broaden the knowledge regarding: (a) the potential of the undercut anchor pull-out process in mining of the rock mass, and (b) estimating the load-carrying capacity of anchors embedded in the rock mass (which is distinctly different from the anchorage to concrete). Undercut anchors are most commonly applied as fasteners of steel components in concrete structures. The new application for undercut anchors postulated in this paper is their use in rock mining in exceptional conditions, such as during mining rescue operations, which for safety considerations may exclude mechanical mining techniques, mining machines, or explosives. The remaining solution is manual rock fracture, whose effectiveness is hard to assess. The key issue in the analyzed aspect is the rock fracture mechanics, which requires in-depth consideration that could provide the assistance in predicting the breakout prism dimensions and the load-displacement behavior of specific anchorage systems, embedment depth, and rock strength parameters. The volume of rock breakout prisms is an interesting factor to study as it is critical to energy consumption and, ultimately, the efficiency of the process. Our investigations are supported by the FEM (Finite Element Method) analysis, and the developed models have been validated by the results from experimental testing performed in a sandstone mine. The findings presented here illuminate the discrepancies between the current technology, test results, and standards that favor anchorage to concrete, particularly in the light of a distinct lack of scientific and industry documentation describing the anchorage systems’ interaction with rock materials, which exhibit high heterogeneity of the internal structure or bedding. The Concrete Capacity Design (CCD) method approximates that the maximum projected radius of the breakout cone on the free surface of concrete corresponds to the length of at the most three embedment depths (hef). In rock, the dimensions of the breakout prism are found to exceed the CCD recommendations by 20–33%. The numerical computations have demonstrated that, for the nominal breakout prism angle of approx. 35% (CCD), the critical spacing for which the anchor group effect occurs is ~4.5 (a cross-section through two anchor axes). On average, the observed spacing values were in the range of 3.6–4.0.

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“…The angles at the base of the cone in reality are almost 2 times smaller than the standard ones, which is the reason that the estimated ranges of the loosening, and hence the volume of the loosened rock mass, are significantly understated. The real loosening ranges (crack propagation) in the light of the few literature items [3,12,19,23] are shown in Figure 4.…”

Section: Introductionmentioning

confidence: 99%

“…Real extent of the loosening process based on literature data: a, b) concrete cone[12,23]; c) radius R observed by test and effective radius R' used in model[3]; d) comparison between LEFM predictions (dashed lines) and experimental crack propagation patterns[19]. LEFM, linear elastic fracture mechanics.…”

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confidence: 99%

Testing the rocks loosening process by undercutting anchors

Siegmund

Kalita

Bałaga

et al. 2020

Studia Geotechnica Et Mechanica

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AbstractThe method of unconventional solid rock loosening with undercutting anchors and the literature analysis of the problem are presented. The tests and test results of the rocks loosening process with a fixed undercutting anchor are described. The tests were carried out within the RODEST project, OPUS 10 competition No. 2015/19/B/ST10/02817, financed by the National Science Centre. Numerical modeling process as well as a series of laboratory and in situ tests were carried out. The test stand equipment and methodology for the in situ tests are presented. The tests were conducted in four mines, which allowed to obtain and determine the following characteristics: loosening force as a function of anchoring depth (for a given type of rock),the range of rock loosening in a function of anchoring depth (for a given type of rock), andloosened rock volume as a function of anchoring depth (for a given type of rock).The in situ test results are compared with the concrete capacity design (CCD) model used for the calculation of anchor load capacity in concrete.

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Pullout Capacity of Headed Anchors in Prestressed Concrete

Cited by 19 publications

References 19 publications

Three-Dimensional Finite Element Analysis of the Undercut Anchor Group Effect in Rock Cone Failure

Three-Dimensional Finite Element Analysis of the Undercut Anchor Group Effect in Rock Cone Failure

Analysis of the Rock Failure Cone Size Relative to the Group Effect from a Triangular Anchorage System

Testing the rocks loosening process by undercutting anchors

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