•Tensile capacity and performance of anchor bolts is affected by the member thickness.•Concrete strength influences significantly the anchorage ductility and stiffness.•Tensile capacity of anchor ...bolts increases by adding steel fibres to concrete mixture.•Anchorage ductility improves considerably in steel fibre-reinforced concrete.
Cast-in-place anchor bolts embedded in plain and steel fibre-reinforced normal- and high-strength concrete members were subjected to monotonic tensile loads. The influence of the concrete member thickness, concrete strength, and the addition of steel fibres to the concrete mixture, on the anchorage capacity and performance was evaluated. The experimental results were evaluated in terms of anchorage capacity, anchorage ductility and stiffness as well as failure mode and geometry. Furthermore, the validity of Concrete Capacity (CC) method for predicting the tensile breakout capacity of anchor bolts in plain and steel fibre-reinforced normal- and high-strength concrete members was evaluated.
The anchorage capacity and ductility increased slightly with increasing member thickness, whereas the anchorage stiffness decreased slightly. In contrast to the anchorage ductility, the anchorage capacity and stiffness increased considerably with increasing concrete compressive strength. The anchorage capacity and ductility also increased significantly with the addition of steel fibres to the concrete mixtures. This enhanced capacity and ductility resulted from the improved flexural tensile strength and post-peak cracking behaviour of steel fibre-reinforced concrete.
The average ratio of measured strengths to those predicted by the CC method for anchors in plain concrete members was increased from 1.0 to 1.17 with increasing member thickness. In steel fibre-reinforced concrete, this ratio varied from 1.29 to 1.51, depending on the member thickness and the concrete strength.
•Analytical study on a type of column base connection: Exposed Base Plate with Extended Anchor Bolts.•Excellent behavior in recent major earthquakes (e.g., 2010 Chile earthquake)•Plastic deformations ...occur only at the anchor bolts, and all other components of the connection (including the column) remain elastic.•Flag-shape, self-centering hysteretic behavior.•A rational design methodology is proposed and validated.
This paper investigates the behavior of a ductile detail of exposed base plates. This detail consists of a base plate anchored to the concrete foundation through bolts extended to a steel chair configuration. The intention is to concentrate plastic strains mainly in the extended region of the anchor bolts, forcing the other connection components to remain elastic. The scientific background of this research consists of a series of sophisticated nonlinear finite element models subjected to a cyclic load protocol in the presence of an axial compressive force. The models were validated against an experimental test reported in the literature. Forces within the connection components, stresses, strain distributions, and deformation modes were examined. A total of sixteen three-dimensional nonlinear models were created using the ABAQUS simulation platform. The models were separated into two groups: the first consists of models with dimensions similar to the specimens tested in recent experimental programs reported in the past, while the second group simulates connections representative of mid-rise industrial frames. Building on the insights gained from the simulations of the first group, a methodology is proposed to design these column base connections. This suggested methodology is validated with the second group of simulations. Results indicate that the studied configuration detail presents some advantages compared with the traditional detail presented in Design Guide 1. For instance, plastic strains are developed almost exclusively in the anchor rods, and no damage is expected at the remaining components. Another essential characteristic is the exposed stretch length, with which it is possible to achieve a target design rotation without significant strain concentrations in the anchor rods. This characteristic facilitates post-earthquake inspections and repairs, and damage is virtually eliminated in the first story.
•Focusing on supporting structures rather than surrounding rocks, an improved numerical simulation approach is proposed.•Both the supporting arch bearing behavior and the separable arch-rock ...interaction is realized.•The breakable anchor bolt model is established to simulate the stretching broken behavior of anchor bolt/cable.
Our goal was to develop an effective research tool for tunnels with significant deformations supported by arch–bolt union system. The improved numerical simulation approach is constructed through additional development of FLAC3D. There are four parts that form the approach: a yieldable supporting arch module, a separable arch–rock interaction module, a breakable anchor bolt module, and a practicable surrounding rock module. The yield criterion of the supporting arch was proposed and embedded in the modified beam element via the FISH language programming. A separation criterion is proposed for the arch–rock interaction link, and the separable arch–rock interaction module is realized through modifying the normal-yield attachments of the built-in arch–rock links. A tensile breakage failure criterion is proposed for the anchor bolt using the ultimate elongation ratio δf of the whole anchor-free part as the criterion. Taking an actual mining roadway tunnel as the simulation object, two simulation schemes adopting the newly improved approach and the original method were carried out respectively, and comparisons of the results show that: (1) the bending moment and axial force at the yielding moment of the compression-bending element change from independent to related after modification, and the computed deviation of the arch model caused by the shortcomings of the original beam element were effectively suppressed; (2) the separable link is proved effective by the supporting forces curves and arch deformation responses; (3) the breaking property of the anchor bolt is implemented, and the response is sensitive; and (4) the surrounding rock controlling results in the modified model scheme are closer to the actual. The analysis shows that the improved numerical simulation approach is much more reliable for large deformation tunnel behavior with arch–bolt union support, especially concerning the bearing and failure behaviors of the supporting arch and anchor bolt.
•Expansion Anchor Bolts (EAB) were used to fasten Aluminum Alloy (AA) plates to strengthen RC beams.•EAB size, spacing and layout were used as varying parameters.•All specimens exhibited more than ...30% increase in their flexural strength.•All specimens exhibited significant increase in ductility upto 84%.•Use of hybrid combination of EAB and epoxy-bonding showed the best performance.
Externally bonded reinforcement (EBR) has emerged as one of the promising techniques for flexural strengthening of reinforced concrete (RC) members due to its practicality and structural effectiveness. However, shortcomings like premature failure modes, cost, labor, and installation time limited its use. Mechanically fastened (MF) Aluminum Alloy (AA) plates instead have the potential to overcome some of these drawbacks by providing strength and ductility, while influencing the failure modes. In this investigation, 16 RC beams were prepared, one beam was left un-strengthened (CB), one was strengthened with an externally bonded (EB) AA plate (CBE), and the remaining 14 beams were strengthened with MF AA plates that varied based on expansion anchor bolts (EAB) sizes, spacing, layout, and the presence or absence of epoxy. The test results indicated that all the specimens with MF AA plates exhibited approximately 30% increase in strength accompanied with drastic increase in ductility up to about 84% compared to specimen CBE. Analytical predictions were made to numerically assess the advantages of using MF systems where ACI 318-19 outperformed ACI 440.2R-17 due to the sufficient composite behavior that allows the AA plates to behave similar to steel reinforcement such that the section has an additional lever arm. It is concluded that the implementation of epoxy and EAB as an alternative anchorage technique serves as a viable approach in enhancing the strength and ductility of RC beams strengthened with AA plates.
This study evaluated the influence of concrete member thickness and size of anchor head on the tensile capacity and performance of anchor bolts in concrete. Anchor bolts at various embedment depths ...(h.sub.ef = 50 to 500 mm 1.97 to 19.69 in.) in concrete members of various thicknesses (H = 1.5 to 5.0h.sub.ef were simulated. Three different sizes of anchor head (small, medium, and large) were considered at each anchor embedment depth. The numerical results were compared with predictions from several theoretical and empirical models, including current design models as well as some test results. The numerical results show that the concrete cone resistance increases with increasing thickness of concrete member and/or size of the anchor head. Simulations also indicate that current design models generally underestimate the tensile capacity of large anchors. Two modification factors are proposed to account for the influence of the member thickness and the size of anchor head. Predictions of anchorage capacity using the proposed modification factors have good correlation with the available test results found in the literature. Keywords: anchor bolt; concrete cone breakout; head size; member thickness; pullout loading; size effect.
•The addition of both types of fibres when used in concrete improved the maximum load and toughness.•A reduction in core concrete temperature of the samples was examined.•The strength of concrete is ...significantly improved when tested at −20 °C, compared to ambient temperature.
Anchor bolts are often fixed into a concrete soffit of structures and they are used in ambient and cold store locations. The chemical anchor bolt relies purely on the tensile strength of the concrete to carry the imposed load, assuming the bond strength of the resin is greater than the tensile strength of the concrete.
The properties of concrete are changed by the addition of both steel and polypropylene fibres. This paper investigates the relative performance of each fibre type with regard to initial and final post crack failure. Anchor bolt pull-out testing was used to determine the maximum load a fixing can hold as well as the residual post crack toughness of a bolt embedded in a concrete block. The concrete used was a C40 design mix and resin anchor bolts were selected for this test for their stress-free conditions prior to loading.
The results showed that the addition of both types of fibres when used in concrete improved the maximum load and toughness of the samples, compared to plain concrete. There was not a significant difference between the results obtained for steel and polypropylene fibres. The effects of a reduction in core temperature of the samples was examined. The results show that the strength of concrete is significantly improved when tested at −20 °C, compared to ambient temperature.
Abstract
The most widely used connection form of the wind turbine foundation and the tower is the foundation ring method. With the popularization and application of high wheel hub and large-capacity ...wind turbines, the anchor cage ring has gradually become the connection method of large-capacity wind turbines. Therefore, the force mechanism of the connection between the foundation ring and the anchor cage ring has become an important issue in the basic design of the wind turbine. In this paper, numerical simulation method is used to analyse the characteristics of the two connection methods and force characteristics of the foundation ring and anchor bolts. The force transmission mechanism and force characteristics of the two connection methods are summarized and the stress distribution of the foundation ring, the anchor cage ring and the nearby concrete are obtained. Finally, the basic strengthening strategies under the two connection methods are clarified.
•Development of a numerical method for the modeling of 3D anchor pull-out from concrete block.•The Drucker–Prager plasticity model is implemented to describe the nonlinear of concrete material.•The ...Hughes and Winget algorithm is integrated in NSPD for large deformation analysis.•The pullout capacity and final failure mode of the anchor obtained are agreed well with the current design formula and the experimental observations.
In this work, a meshless analysis based the non-ordinary stated-based peridynamic method (NSPD) is performed to solve the problem of anchor bolt pullout in plain concrete. The peridynamic method is adopted as an analysis tool to avoid the difficulties found in FEM. In the analysis, the Drucker–Prager plasticity model is implemented to describe the nonlinear relationship between force vector state and deformation vector state. The Hughes and Winget algorithm is integrated in NSPD for large deformation analysis. The whole progressive failure process of the 3D anchor system, consisted of five groups with different embedment depth or member thickness, are investigated. Numerical analysis results indicate that the obtained peak pullout load shows good agreement with the current design formula and the crack branching of anchoring system also agreed well with the experimental investigations.
•An experimental research work detailing the innovative non-destructive testing method that employees Schmidt hammer rebound number, R for the accessing the pull-out strength, N of 144 anchor bolts ...is presented.•The valuable addition of the proposed method is to allow users to estimate the pull-out strength of steel anchors embedded in concrete without causing any damage to the surrounding structure.•Furthermore, a detailed Latin Hypercube Sensitivity analysis is performed for describing the influential factors affecting the pull-out strength of steel anchors embedded in concrete.
Anchor bolts are extensively employed in the various industries such as construction, mechanical and mining. Their applications range from installing permanent objects such as hybrid structures, lighting piles, direction signs to structures installed for serving temporary purpose. Several destructive testing methods have been proposed to investigate the pull-out strength of anchor bolts. However, the first real non-destructive testing method that used Schmidt hammer rebound number to estimate the load carrying capacity of anchor bolts was successfully proposed by the authors. In this method the authors successfully relate the pull-out strength of the steel anchors, N, embedded in the concrete with the Schmidt hammer rebound number, R. The research team was successful in identifying anchor bolts with improper installation resulting in lower pull-out strength. It was observed during experimentation that strength of steel anchor bolts depends upon several factors such as concrete strength, embedment length, bolt diameter, its alignment and rebound number. The cut-off value, R, of 56, 61 was identified for steel anchors of 8 mm, 10 mm diameters with embedment lengths of 50 mm and the R value of 55, 53 and 51 was identified as cut-off for 12 mm, 16 mm and 20 mm diameters with embedment lengths of 50 mm and 70 mm, respectively. Anchors depicting higher rebound values can be considered as properly installed while anchors with lower rebound value indicate defects in installation and quality of surrounding concrete. Furthermore, a detailed random parametric analysis employing Latin Hypercube Sampling method to conduct sensitivity analysis of 144 anchor bolts test data. Five diameter anchor bolts with two embedment depths were tested and analyzed. Through the analysis of experimental data, the influence of each parameter was investigated in order to ascertain its impact on the load carrying capacity of the anchor bolts. It is confirmed that the alignment of the anchor bolt is most dominant factor among all random factors considered in the analysis. Furthermore, the embedment length holds a larger influence on the pull-out strength as compared to the bolt diameter.
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