Behavior Of Anchors Research Articles

Numerical study on uplift capacity and behavior of plate anchor considering different dilation angles

Numerical study on uplift capacity and behavior of plate anchor considering different dilation angles

Tensile Behavior of Small Screw Anchors under Cyclic Crack Openings

Tensile Behavior of Small Screw Anchors under Cyclic Crack Openings

Finite element analysis of the influence of dowel angle on CFRP anchors

In current retrofitting design guidelines, carbon fiber reinforced polymer (CFRP) anchors are recognized as an efficient and minimally invasive approach to delaying delamination. Recent research has demonstrated the capability of Finite Element Method (FEM) models to accurately reproduce the behavior of experimentally tested CFRP anchors. Among the various design parameters of CFRP anchors, the dowel angle is one of the least studied, yet it is a crucial factor. There is limited experimental data available for this parameter and there are no numerical models focused on its influence on anchor behavior. This article reports the results of a comprehensive three-dimensional FEM model for CFRP anchors, with a particular emphasis on varying dowel angles. The model accuracy is verified against direct shear joint tests drawn from the literature, including aspects such as the maximum load, load-slip curves, and the distribution of strains along the CFRP. Subsequently, the model is used to conduct a sensitivity analysis of the dowel angle in conjunction with other important parameters for the design of CFRP anchors. These parameters are the length of the CFRP ply behind the anchor, the number of anchors within the joint, the fiber content, and the depth of the dowel. The results obtained from the modeling show an important influence of the dowel angle on the effective use of carbon fibers and the enhancement of joint strength. By offering insights into the interactions between the dowel angle and other design parameters, this research contributes information that can guide the development of design guidelines for the optimization of CFRP anchor systems.

An innovative prestressing system of prestressed carbon fiber sheets for strengthening RC beams under flexure

An innovative prestressing system was developed in this study, which can effectively anchor the prestressed carbon fiber sheets as well as conveniently apply prestress to the carbon fiber sheets. Tensioning tests of the carbon fiber sheet-anchor assemblies were first conducted to verify the anchorage behavior of anchors. Then this prestressing system was used for strengthening reinforced concrete (RC) beams to further verify its feasibility and investigate the effect of the impregnation and curing conditions of the carbon fiber sheets on the flexural strengthening efficiency. The results indicated that the tested ultimate capacity of the carbon fiber sheet-anchor assembly reached 72.1∼97.9% of the theoretical ultimate capacity of the carbon fiber sheet based on different impregnation and curing conditions. The concrete crushing failure and rupture failure of prestressed carbon fiber sheets occurred in the strengthened RC beams. The cracking and yielding loads of the RC beams with prestressed sheets were increased by 56.7∼68.5% and 21.7∼30%, respectively, while those with non-prestressed sheets were increased by 27.3% and 13.7%, respectively. The ultimate load was significantly affected by the impregnation and curing conditions. The prestressed carbon fiber sheets with the uncured full impregnation condition were not superior to the non-prestressed sheets in terms of the ultimate load, whereas the cured full impregnation and partial impregnation conditions were more effective than the uncured full impregnation condition. Finally, theoretical equations were used to calculate the cracking, yielding, and ultimate moments of RC beams strengthened with prestressed carbon fiber sheets.

Anchors to Solid Clay Brick Masonry in Tension: Behavior under Monotonic and Repeated Loading for Constant Embedment Depth

This paper presents a part of an extensive experimental campaign performed at the National Technical University of Athens (NTUA) with the purpose of investigating the behavior of chemical anchors embedded in solid brick masonry. Anchors are tested in tension under monotonic or repeated loading. All tests are performed under displacement-controlled conditions. The experimental setup and the instrumentation are presented, along with the investigated parameters and the rationale for the selection of the values of those parameters. In this part of the experimental work, comprising fifty-six (56) tests, the examined parameters are the anchor locations (in mortar joints and in the center of bricks), the state of the substrate (cracked or uncracked), the width of the crack crossing the anchor or at its vicinity (up to 1.20 mm), as well as the loading history (monotonic or repeated). In the tests presented herein, the embedment length of the anchors is equal to 100 mm. The anchors are embedded in solid brick masonry wallettes, and subjected to a normal compressive stress equal to 0.20 MPa. The observed failure modes are explained, and the overall behavior of anchors subjected to tension is presented and commented upon, along with the effect of the investigated parameters on the measured tension resistance, and on the corresponding displacement.

An efficient approach to tackle the challenges of LDFE modelling of plate anchor-chain system during installation process

This technical note presents an efficient approach to tackle the challenges in large deformation finite element (LDFE) modelling of plate anchor-chain system during installation process. This is realised by using a local coordinate system based on the displacement-control technique, where the chain loading direction is updated compatibly with the anchor behaviour at each calculation increment. The effectiveness of the approach is demonstrated through two analysis examples that model the anchor installation (keying) process. The results agree well with established analytical solution based on plasticity analysis, which was developed based on deeply embedded anchor. The LDFE results numerically testify that plate anchors with well-designed padeye position are able to dive into deeper seabed under chain loading, where this concept was only suggested in previous analytical and plasticity analysis.

Load transfer behavior and interference effect of load distributive compression anchor in residual soil

Load transfer behavior and interference effect of load distributive compression anchor in residual soil

Failure Behavior and Surrounding Soil Stress Responses of Suction Anchor in Low-Strength Muddy Clay

Anchorage failure of a suction anchor is more likely to occur in low-strength muddy clay. This paper focuses on the failure behaviors of suction anchors and muddy clay stress responses. The centrifugal model test was used to study the loading processes of suction anchors with various pulling angles. Firstly, the multi-stage developing process of anchoring force was analyzed according to the test results. Numerical modeling was used to validate the test results. The displacement of the suction anchor and muddy clay soil were analyzed using the numerical results. Then, the numerical and testing results were compared to analyze the horizontal soil pressure responses around the suction anchors. It was found that the change in loading direction affected the distribution and development of soil stress. The horizontal soil resistance played a crucial role in improving the bearing capacity. The soil stress variation and anchor displacement revealed that the suction anchors exhibited multi-attitude coupling movement during the inclined pulling. The vertical pulling suction anchor showed shear–slip failure behaviors, while the inclined pulling suction anchors showed compression–shear–slip coupling failure behaviors. The results of this study provide insight into the interaction mechanism between suction anchors and muddy clay, serving as a reference for the design and application of suction anchors.

Behavior of Anchors Embedded in Concrete Damaged by the Maximum Considered Earthquake: An Experimental Study

The article presents experimental tests carried out to investigate the effect of crack width (0.4, 0.8, 1.5, and 3.0 mm) on the behavior of anchor bolts under static and dynamic loading. Ultimate loads for anchors reached 220 kN depending on the anchor type, the diameter, and the crack opening width. Mechanical and bonded anchors were studied as the most frequently used anchor types. Two states of concrete, resulting from the design earthquake and the maximum considered earthquake, were simulated in the course of the experiments. Within the framework of the study, dependencies between the bearing capacity and stiffness of anchorages, on the one hand, and the level of concrete damage, on the other hand, were identified for different types of anchors. The data, generated in the course of the study, were used to identify the types of anchorages recommended for embedment in seismic areas. Plasticity coefficients and seismic load reduction coefficients were determined for different types of anchors and levels of concrete damage as a result of experimental studies. Reduction coefficients can be contributed to the design of anchorages embedded in seismic areas.

Effects of soil remoulding on keying behaviours of strip plate anchors with padeye offset

This paper reports the effect of soil remoulding on embedment loss and pullout capacity of strip plate anchors with padeye offset in normally consolidated clay during keying through large deformation finite element (LDFE) analysis. The effects of strain rate and soil remoulding are considered during keying process of plate anchors. First, the LDFE results are compared with theoretical solutions, centrifuge test results, and LDFE data available in the literature, which shows a good agreement. Then, the influences of initial embedment depth, load eccentricity, padeye offset and soil sensitivity on the embedment loss and pullout capacity of strip plate anchors during keying are investigated. The LDFE results show that the padeye offset and the soil remoulding have significant effects on the ultimate embedment loss and pullout capacity. To assess the keying behaviour of plate anchors, an equivalent soil strength is introduced. A combined factor and an equivalent ultimate pullout capacity are adopted to estimate the embedment loss and ultimate pullout capacity of strip plate anchors in normally consolidated clay, respectively.

Hybrid assessment of fiber orientation influence on the load resistance of anchors in SFRC

AbstractThe consistent evolution of concrete has led to a variety of concrete types that enhance the material's versatility, cost‐efficiency, and sustainability. Despite the rapid development and extensive research regarding steel fiber‐reinforced concrete (SFRC) in the last decades, there are still knowledge gaps on the material's resistance against locally applied tension loads on anchor bolts, as well as the interaction of possible nonhomogeneous fiber orientations on the anchorage axisymmetric stress field. This aspect becomes particularly relevant since anchors are placed at the component boundaries, where fibers tend to align parallel to the external surface. Through an innovative experimental investigation on 64 single‐bonded anchors using layer‐casting concrete and a supporting set of nonlinear finite element simulations, this work aspires to exhibit the influence of controlled unidimensional fiber orientation on the load‐bearing capacity and behavior of anchorages in SFRC.

Numerical study on keying capacity of gravity installed anchors in sand

Abstract Being the latest representative of GIAs, the OMNI-Max anchor performs comprehensive behaviors in the seabed, like keying and diving, by adjusting orientation and position to derive higher capacity and therefore to avoid anchor failure. Current research of OMNI-Max anchors is concentrated on clay, while there is a notable gap of the work on sand. During the keying process of GIAs, many factors may influence the keying capacity, such as the embedment depth, the anchor orientation, the rotational center, the bearing area and the soil strength. Large deformation finite element analyses combined with a bounding-surface plasticity constitutive model are performed to investigate systematically the keying behavior of GIAs. A series of analytical cases involving multiple factors are designed and analyzed to explore the effects of various factors on the keying capacity of GIAs, defined by the soil resistance coefficient during keying. The soil resistance coefficient increases with increasing soil density, while it tends to be stable with the increase of the embedment depth. The closer the rotational center approaches to the two ends of the anchor, the greater the soil resistance coefficient becomes. An explicit expression of the soil resistance coefficient during keying is derived to quantify the effects of various factors. These findings are helpful to understand further the comprehensive anchor behaviors and to promote the application of GIAs in offshore engineering.

Effective prediction finite element model of pull-out capacity for cast-in-place anchor in high strain rate effects

Cast-in-place anchors are being increasingly used in many applications including building construction, bridge, and power plants. The anchorage to concrete systems are subjected to tensile, shear and combined loads from a variety of loading circumstances including static, dynamic, and shock loading. Despite extensive studies on these systems, reliable numerical models for predicting the behavior of these anchors are still limited. Therefore, this paper investigated the tensile behavior of cast-in-place anchorage to concrete systems, to propose an effective model for reproducing anchorage behavior using finite element (FE) methods. Experiments and code-based models for the anchorage system in tension were used to evaluate the numerical models for cast-in-place anchors in concrete, and the most suitable model, with advantages in accuracy and saving analysis time, was chosen. Finally, the FE model was used to study the tensile capacity and related dynamic increase factor for various strain rates, anchor diameters, and embedment depths.

Pullout behavior of tree root-inspired anchors: development of root architecture models and centrifuge tests

Pullout behavior of tree root-inspired anchors: development of root architecture models and centrifuge tests

A coupled thermal-analytical and mechanical approach to investigate the behavior of bonded anchors cured at sub-zero temperatures

In post-installed connection in reinforced concrete structures, bonded anchors are commonly adopted when elevated mechanical performances are required. Such performances may be significantly impaired by adverse service conditions, above all temperature variations with respect to room ambient one. It is also generally acknowledged that the curing temperature may impact on the anchor performances, to the extent that all the main existing qualification procedures assess the anchor behavior when cured at different temperatures, in particular below zero Celsius degree. However, among the few investigations focusing on the impact of a low curing temperature on the long term behavior of an anchor, a low effort exists in addressing the relationship between the anchor mechanical behavior and the thermal properties of the bonding agent. The paper proposes a coupled thermal-analytical and mechanical approach to detect potential critical issues in the long term mechanical behavior of the anchor as a function of the adhesive behavior, as investigated by thermal or thermo-mechanical analyses. To the scope, a wide investigation on two adhesives is carried out comprising MDSC, DMA, pull-out and sustained load tests. On the basis of the obtained results, it is concluded that some thresholds in the variations of degree of conversion and phase transition temperatures may indicate a negligible impact of a low curing temperature on the anchor mechanical behavior, but also that existing qualification procedures are not able to capture the anchor behavior, when cured at low temperatures and subjected, during its service life, to temperatures higher than room ambient one.

Tensile behavior and failure modes of expansion anchors in High-Performance Steel Fiber Reinforced Concrete (HPSFRC)

To investigate the tensile(pullout) behavior of expansion anchors in High-Performance Steel Fiber Reinforced Concrete(HPSFRC), 30 valid unconfined tension(pullout) tests on expansion anchors, studying the effects of different steel fiber content(0.0 %, 0.5 %, 1.0 %, and 1.5 %), embedment depths(25 mm, 35 mm, and 45 mm), and anchor diameters(10 mm and 12 mm) on the tensile behavior of anchors. A total of seven failure modes, including different types of mixed modes, are observed. The incorporation of fibers reduces the anchorage stiffness, increases the ductility, and improves the post-peak performance of the tensile behavior of anchors. Effective embedment depth(Hef)exerts a great influence on the failure mode; as Hef increases, the dominant failure mode transits from the concrete breakout to the pull-through and mixed failure modes, and finally the steel failure mode. The increase in Hef also leads to increases in the ultimate tensile strength of the anchor(Nu) and the anchorage ductile. For the same Hef and fiber content, compared to the smaller diameter(D), Nu for the larger diameter is larger but the pullout ductility is weaker. A modified model considering the influence of steel fibers is proposed to predict Nu of CB mode in HPSFRC, and it results in more accurate predictions compared to the existing prediction models(CCD model, Toth model). An existing prediction model for PT mode in normal concrete has been proven to be applicable for anchors HPC/HPSFRC.

Numerical study on the behaviour of horizontal anchor using upgraded SANISAND-MS

Horizontal plate anchors are widely used to secure tension leg platforms via mooring lines. A thorough understanding of the monotonic, cyclic and post-cyclic behaviour of plate anchors is essential to accurately estimate plate anchors' capacity. This paper presents a systematic investigation of horizontal rectangular plate anchors subjected to vertical monotonic and cyclic loads in quartz sand under drained conditions using three-dimensional finite-element simulations. The upgraded SANISAND-MS model is employed to accurately capture sand's ratcheting behaviour. The monotonic uplift load is affected by the contact types used between the soil-anchor interface, and it increases with increasing embedded depth ratio, aspect ratio, and relative density. The results of cyclic tests reveal that in loose and dense sands, the cyclic amplitude ratio and cyclic asymmetric ratio affect the displacement accumulation at the cyclic stage. The cyclic loading leads to a higher post-cyclic uplift load than the monotonic tests. Moreover, the post-cyclic uplift load increases more in tests with a high cyclic amplitude ratio. Investigation on local soil responses shows that this can be attributed to sand's densification, which increases sand's strength and stiffness. The study also supports the development of long term analysis for anchoring systems subjected to cyclic loading in offshore applications.

Bond of steel reinforcement based on detailed measurements: Results and interpretations

AbstractRebar‐to‐concrete bond is a fundamental aspect of the behavior of reinforced concrete structures. The characterization of the interface response is challenging due to the complexity of the physical phenomena and the large number of factors involved. Locally, the response is characterized by the bond–slip relationship, which is typically obtained experimentally from pull‐out tests with short bonded lengths. The behavior of longer anchorages in structural members differs significantly from short tests as the bond stress distribution is not uniform. In this context, this paper presents the results of a comprehensive research aiming to establish a better relationship between the local bond–slip response from short pull‐out tests and the response of medium‐length anchorages. The results of an experimental program are presented, including the effect of some parameters commonly found in structural applications, such as casting conditions, clear cover, rib geometry, and rib orientation. A local bond–slip relationship for well‐confined conditions is proposed on the basis of the tests performed by the authors and on the examination of a database on short pull‐out tests from the literature. Based on this relationship and some mechanical considerations, the local bond–slip relationship for unconfined conditions can satisfactorily be formulated based on crack‐width measurements from the concrete surface. This can be useful for the assessment of existing structures and can be seen as a step forward in the development of a consistent mechanical model for bond.

Development and Finite Element (FE) analysis of a novel short hip stem concept

IntroductionIn order to improve the anchorage behavior of short hip stems, this development project aims at designing a short hip stem concept that preserves the femoral neck and minimizes interference with the physiological stress distribution of the femur. The new design will be evaluated according to ISO 7206-4 which is the standard for testing Implants for surgery. MethodsBasic CAD models based on an established short stem prosthesis were created and evaluated using finite element analysis. The best design was further developed to achieve a more deformable stem while maintaining stability. The model was validated through in vitro testing. ResultsThe “H-Beam” short stem showed a higher degree of deformation of approximately 142–144% compared to the established short stem. The FE model had a relative error of 0.98% and 1.07% compared to the in vitro tests. An operating procedure was outlined for this new short stem design. DiscussionThe FE model is deemed valid due to small differences in comparison to in vitro testing. The short-stem prosthesis is more flexible and can be easily adapted to individual anatomy during surgery. The prosthesis length is similar to conventional prostheses, but the new stem design could allow better and faster osteointegration while preserving the cancellous bone structure.

The evolutionary game analysis of the decision-making behavior of live streaming stakeholders under the value co-creation.

Integrity-linked issues have become increasingly serious and attracted considerable attention regarding the sustainability of live streaming; therefore, live streaming anchors and suppliers have become increasingly concerned about their ongoing marketing. Moreover, streaming platforms are also beginning to focus on sustainable development. Determining how live streaming anchor behavior, supplier behavior, and streaming platform strategic decision affect live streaming is essential for achieving the healthy and sustainable development of live streaming ecosystems. However, the game among live streaming anchor behavior, supplier behavior, and streaming platform strategic decisions, which the live streaming ecosystem strongly depends on, has attracted little attention. This study constructed a game model of value co-creation evolution in live streaming ecosystems, with the live streaming anchors, suppliers, and streaming platforms as the main subject. The evolutionary stable strategies of the game were analyzed, and the influence of typical factors on the system was discussed. The results showed that the best evolutionary stability strategy is that live streaming anchors and suppliers choose honesty, and streaming platforms have strict regulation, which is the optimal strategic objective for value co-creation. The appropriate rewards and punishments inherent in a streaming platform can help regulate the behavior of the live streaming anchor and supplier; specifically, great rewards and severe punishments of the streaming platform can be applied to incentivize the honest behavior of the live streaming anchor and supplier. This study provides insights for designing appropriate policies for live streaming platforms to promote sustainable development.