Search

This paper presented the experimental results of the strength capacity of studs embedded centrally in concrete with red mud synthetic coarse aggregates, with the variation of the handcrafted headed stud thickness (3.17, 4.76, 6.35, and 7.9 mm) and no shank bond influence with concrete. The results regarding the compressive strength of concrete showed considerable strength gain with synthetic coarse aggregate, ranging from 27.00 to 43.50 MPa, while in concrete with natural coarse aggregate, the variation was 27.00 to 36.50 MPa. Also, it was observed that the cracking in the concrete matrix of the synthetic coarse aggregate occurred in the aggregate instead of the transition zone, as occurred with the natural coarse aggregate concrete. However, the solid morphological formation of synthetic coarse aggregate provided excellent chemical adhesion to the headed stud, providing a hardening failure behavior after reaching the yield strength value of the steel bar with higher displacements. This can enable the optimized consumption of materials in the dosage of low‐strength structural concrete and the anchoring application of studs with smaller‐headed thicknesses, up to 8% of head diameter, generating economy and sustainability. [ABSTRACT FROM AUTHOR]

With the increasing use of fibre-reinforced concrete, e.g., in industrial floor and tunnel construction, the associated fastening technology in this material has increasingly become the focus of scientific attention in recent years. Over 25 years ago, design and assessment guidelines for anchoring systems in reinforced concrete were established, which have since evolved into comprehensive regulatory standards. However, these standards only address plain and rebar-reinforced concrete as anchoring bases, neglecting fibre-reinforced concrete. The design of anchorage systems in fibre-reinforced concrete has not yet been standardised. Recent studies and product certifications accounting for steel fibre reinforcement are now seeing their way to publication, supported by a fair amount of scientific research studies. This paper aims to elucidate the effects of polymer fibre reinforcement in this application through a systematic investigation. Experimental studies were conducted to evaluate the system's load-bearing behaviour failing with concrete breakouts under tensile loading. By incorporating the determined material properties of polymer fibre-reinforced concrete and their mathematical interpretation, alternative model proposals are presented to assess concrete breakout resistance. The addition of polymer fibres significantly improves the load-bearing capacity and ductility of concrete under tensile loads, transforming its quasi-brittle response into a more ductile behaviour. Although the fibres had a minor impact on overall material strength, their influence on the tensile capacity of the anchors reveal a 15–20% increase in load resistance and up to a doubling of the failure displacements. [ABSTRACT FROM AUTHOR]

I-shaped concrete girders are widely used in precast bridge and roof construction, making them a common structural component in existing infrastructure. Despite well-established strengthening techniques using various innovative materials, such as externally bonded carbon fibre reinforced polymer (CFRP) reinforcement, the shear strengthening of an I-shaped concrete girder is not straightforward. Several research studies have shown that externally bonded CFRP reinforcement might exhibit early debonding at the concave corners of the I-shape, resulting in a marginal increase in shear capacity. This research study aims to assess the performance of two different CFRP shear strengthening strategies for I-shaped concrete cross-sections. In the first strategy, CFRP was bonded along the I-shape of the cross-section with the provision of additional anchorage. In the second strategy, the I-shape was transformed into a rectangular shape by using in-fill blocks over which the CFRP was bonded in a U-configuration. In addition to the strengthening strategies, the investigated parameters included two different materials for the in-fill blocks (conventional and aerated concrete) and two different anchoring schemes (bolted steel plate anchor and CFRP spike anchor). To avoid testing on large-scale girders, a new test methodology has been implemented on concrete I-sections. The test results demonstrate the feasibility of comparing different shear strengthening configurations dedicated to I-sections. Among other findings, the results showed that the local transformation of the I-shape to an equivalent rectangular shape could be a viable solution, resulting in shear strength enhancement of 12% to 53% without and with the anchorages, respectively. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study on the behavior of the load capacity of handcrafted studs symmetrically embedded in concrete reinforced with steel fiber. A total of eight blocks were subjected to pull-out tests. The main variables were stud head thickness (3.17, 4.76, 6.35, and 7.9 mm) and concrete type. The results showed no significant difference in the mean pull-out strength in both types of concrete mixtures: conventional and fibrous. Therefore, the effect of steel fiber addition tends to reduce the inclination plane of cracks, changing the mode of abrupt failure to more ductile. Moreover, in conventional concrete, the thickness th=7.93 mm (0.20 dh) lost about 15% of the pull-out strength compared to the thickness th=3.17 mm (0.08 dh); in contrast, it obtained a gain of 5% in concrete with the steel fiber. That is, a thickness of approximately 10% of the head diameter can adequately provide satisfactory results in embedment with or without the addition of the steel fiber for fc=35 MPa. In addition, the literature models were more conservative. Also, a modified concrete capacity design method was proposed, considering the head thickness and the empirical factor for concrete breakout strength adjustment, k=20. The results were satisfactory, with an average of 1.00 and a coefficient of variation of only 6% in steel fiber concrete. [ABSTRACT FROM AUTHOR]

The concrete capacity design (CCD) method for the design of anchorages comes with a pre‐requisite that the base plate connecting the anchors of a group should be "sufficiently stiff." This article addresses a frequently and vastly discussed topic in fastening technology, namely "What a sufficiently stiff base plate actually means?" The qualitative definition used by the codes requires that the deformation of the base plate should be small compared to the anchor displacements, in addition to the requirement that the base plate should remain linear elastic. This requirement indirectly ensures that the forces among the anchors of the group are distributed in a linear manner, which is the primary requirement to apply the CCD method for design of anchorages. Such a qualitative definition has raised more questions than answers and haunts the fastening technology community. Perhaps the possible solution to this problem requires asking the question differently, that addresses the problem directly: How can it be ensured that the tension forces among the anchors of a group are distributed in a linear manner? This paper first discusses the problem in detail highlighting several issues in the current approach and later provides an overview of an assessment method in form of a set of criteria that can be used to evaluate whether the tension force distribution is linear for an anchorage with a given anchor pattern, baseplate, attachment, and load case. The principle of the approach is based on a combination of simple mathematical formulations and the evaluation of finite element calculations performed on anchorages modeled with base plate, attachment, and anchors. The proposed formulations are described, and it is explained why they are adequate to find practical and safe general solutions to the problems. The application of the set of criteria allows the calculation of an optimum base plate thickness, sufficient to distribute the forces linearly among the anchors, without being overly conservative. [ABSTRACT FROM AUTHOR]

In civil engineering, the analysis and characterisation of structural phenomena is key for the deviation of mechanical models and strongly depends on experimental studies. For this reason, the development of new measurement techniques plays a crucial role in research to allow capturing the mechanical behaviour of structures. In this context, distributed fibre optic sensing (DFOS) gained attention during the last years. Advantageous properties such as minimal invasiveness and quasi-continuous strain measurement enable new possibilities in structural monitoring. DFOS is able to sense minimal strain variations, yet this often results in recording unwanted anomalies. Thus, to generate the best results from raw measurement data, it is crucial to use a robust and reliable post-processing procedure. In order to meet this requirement, the software solution FOS Evaluator was developed using the Python programming language, targeting the most important aspects that may occur when using DFOS. Those aspects comprise a high data volume, disturbances and anomalies in the measured data and the necessity to carry out calculations with acquired data sets. In this paper, functionality and background of FOS Evaluator are presented and discussed. Furthermore, several methods for post-processing and evaluating DFOS measurements are presented, consisting of multiple functions for reducing, cleaning, or smoothing strain data, and calculating various mechanical properties from filtered measurements. Finally, the functional scope of FOS Evaluator is illustrated by various application examples in structural concrete. [ABSTRACT FROM AUTHOR]

A beam‐end test is proposed in this paper and in the new fib Model Code 2020 to determine the effects of concrete type, confinement effects, and casting position on the anchorage strength of reinforcing bars. Two bars are cast in each specimen (in the two opposite corners), one in a "good" casting position and the other in "poor" casting position. The proposed test aims to be an economical bond test capable to represent actual conditions of anchored bars in real design practice. The test is also intended to verify whether existing provisions for bond and anchorage in the fib Model Code are suitable in nonconventional concrete. The validity of the proposed beam end type bond test is assessed by the results of more 60 tests on rebars having anchorage length of about 20 times the bar diameter in plain concrete, in fiber reinforced concrete, and in recycled aggregate concrete. Experimental results provide information both on the "top cast effect" in three types of concrete and on the effectiveness of fib Model Code provisions for anchorage when nonconventional concrete is used. [ABSTRACT FROM AUTHOR]

This paper presents experimental and theoretical results for the pullout resistance of anchor studs embedded in concrete blocks with inclined planes that simulate punching. This type of reinforcement has been widely studied to combat punching between the slab–column connection, but little information is available about its effect on the region of the inclined shear plane. To simulate this situation, six concrete blocks were made with a single embedded stud; the inclination planes were varied (18°, 30°, and 45°). The effective heights were 50 and 75 mm, and the section widths were 300 and 500 mm. The theoretical analysis was carried out by comparing the estimated load obtained from analytical models found in the literature with the failure load of the tested specimens. The results showed that the inclination plane did not significantly influence the pullout loads of the studs for the studied effective heights, because the configurations generated by the failure surface of the concrete cone trunks tended to stabilize in tension. However, the series with the 30° angle had slightly higher failure loads. The variation in concrete compressive strength did not influence the failure loads, revealing that the concrete strength grade <40 MPa can be an economical alternative in the design of concrete blocks or slabs reinforced with inclined studs. [ABSTRACT FROM AUTHOR]

• A new analytical approach to predict the bond behaviour of mechanically anchored FRP-to-substrate joints is proposed. • The end anchorages of the bonded joints are simulated through a spring with a linear behaviour. • One unique function is used to predict all the stages that the interface undergoes until complete debonding. • The Finite Element Method is used to validate the proposed analytical approach. • The good accuracy obtained in all studied joints suggests that the proposed analytical solution covers a wide range of cases. Fibre-reinforced polymers (FRP) are often externally bonded (EB) to concrete, steel or timber structures for structural strengthening purposes. In the EB reinforcement system, the bond between materials is critical for the success of such a bonding system. However, the system is prone to debond at an FRP strain level much lower than its rupture value. For this reason, it is often necessary to use end anchorages in FRP-strengthened beams to delay or avoid this premature debonding of FRP from the beams. To better understand the debonding process of mechanically anchored FRP-to-substrate joints, the present work proposes a new analytical approach that considers an elastic end anchorage, which can simulate, through a spring, the slips developed in an end anchorage such as an FRP U-wrap jacket, FRP spike anchor, steel plate anchorage, among others. This new approach can also simulate the bond performance of FRP-to-substrate joints with no end anchorages by assuming that the stiffness of the end anchorage is zero. Expressions for defining the load-slip curves, FRP strains, interfacial slips, and bond stresses developed throughout the bonded length are derived and validated against the results from the Finite Element Analysis (FEA). In the end, the model was used to simulate several experimental tests on mechanically anchored FRP-to-substrate joints available in the literature. Despite its simplicity, the proposed analytical approach covers wider situations that no other known similar approach can deal with. [ABSTRACT FROM AUTHOR]

This study aims to strengthen reinforced concrete (RC) beams having insufficient shear capacity using Carbon Fibre Reinforced Polymer (CFRP) members and innovative anchorages. An innovative method is also proposed for strengthening beams in interaction site of adjacent structures. Test results show that the behaviour of beams has been improved with CFRP elements. The nonlinear finite element (FE) method; as well as American and Italian guidelines; are used to estimate theoretical capacity of the beams. Test results are compared with theoretical results. It can be concluded that proposed methods can be used reliably; and that the design of RC beams strengthened with these methods can be performed by design engineers based on simple calculations.

The use of soft computing techniques is becoming more common in providing solutions to complex engineering problems such as the concrete breakout strength of anchor. Available techniques include semi-empirical equations that are known to over or underpredict and some soft computing techniques that is incapable of generating predictive equations. This study proposes a gene expression programming (GEP)-based mathematical model to predict the concrete edge breakout capacity of single anchors loaded in shear. In doing so, an experimental database compiled by the American Concrete Institute (ACI) Committee 355, containing 366 samples, was used for the model training and testing. The independent variables considered in the model development are the edge distance, anchor diameter, embedment depth and concrete strength. Moreover, the predictive performance of the developed model was compared to that of the existing models proposed in ACI 318 and the Eurocode 2 (EC2) design standards. The assessment showed that the proposed GEP-based model provided a much more uniform and accurate prediction of the actual strength than the models in the existing design standards. The proposed mathematical model is simple and robust and is expected to be very useful for evaluating the concrete breakout shear capacity of single anchors in pre-planning and pre-design phases; that is, towards inclusions in design standards. [ABSTRACT FROM AUTHOR]

Breaking load at dowel hole (FDH) value is considered as an important design parameter for mounting natural stones, which are preferred as cladding material in high-rise buildings, on building facades due to their esthetic appearance, ease of production and installation, and resistance to external climatic conditions. In this study, rock samples were prepared from 16 different carbonate originated natural stones, and the relationships between FDH and other some physical and mechanical rock properties have been investigated. Accordingly, it was determined that there are more meaningful relationships between the FDH values and the mechanical properties of the rocks such as uniaxial compressive strength, Brazilian tensile strength, and flexural strength in comparison to their physical properties through simple regression analyses. In addition, two models with high correlation coefficients (0.82 and 0.86) obtained by the multiple regression method were proposed to estimate the FDH values, and the prediction ability was compared with the results of previous studies. Thus, it can be concluded that, when the basic mechanical strength values of natural stones to be used as cladding in buildings are known, the FDH values can be estimated quickly and reliably with the help of the equations proposed in this study. [ABSTRACT FROM AUTHOR]

This study proposes a practical solution for installing anchoring elements on hard or old concrete surfaces to receive tensile forces. For this situation, where the anchorages will be postinstalled, there is often no depth in the concrete base that meets the minimum straight length of standard anchoring. Thus, the use of headed studs or hooked anchor bolts are the most recommended solutions, but the procedure for installing these elements is still the subject of experimental investigations. Then, the technique of postinstallation of headed studs in hardened concrete niches and the use of structural epoxy resin in the new-old concrete interface is presented. Additionally, the influence of the addition of steel fiber on the anchorage studs performance was also evaluated. [ABSTRACT FROM AUTHOR]

The prestressed unidirectional carbon fibre reinforced polymer (CFRP) strips are currently often used for flexural strengthening of concrete structures. To ensure reliable strengthening, strips have to be anchored at their ends to the surface. However, anchoring of unidirectional CFRP strips is difficult because of their weak transversal mechanical properties. Although several CFRP strip anchorage approaches have been developed to date, only very few were applied on-site. The paper presents the development of hybrid bonded/bolted anchorages of CFRP strips used in a novel prestressing system. The anchorages are made of thin steel plates, clamped with the high-strength friction grip (HSFG) bolts and epoxy adhesive, to fix the CFRP strips. The paper describes the results of full-scale tests carried out on a series of axial tensile specimens. The developed anchorage has an ultimate tensile strength of about 200 kN, i.e. 70% of the ultra-high CFRP strips' strength, which is sufficient for strengthening purposes. After a series of tests in the laboratory, the anchorages have been implemented on-site and an example is presented in the paper. [ABSTRACT FROM AUTHOR]

The use of bundled bars in highly loaded concrete members instead of individual bars can reduce or even avoid reinforcement congestion, allowing easier placing and compaction of concrete, since bundles (with two or more side‐by‐side bars) are less obstructive to fresh‐concrete flow. However, there is still a lack in knowledge of the fundamental phenomena related to the bond behavior of bars in bundles. Therefore, design code rules for anchorages and splices differ significantly among International Standards (Eurocode 2, fib Model Code 2010, and ACI 318–19). The present paper reports the results of more than 100 pullout tests with short embedded length with the aim of comparing the local bond behavior of bundles with that of corresponding notional individual bars. Among the three criteria usually introduced to compare bundled and individual bars, based on the concepts of "equivalent sectional area," and "minimum or maximum sectional perimeter," the first and the second are introduced in this paper. Experimental results show that both criteria are suitable methods for evaluating the bearing capacity of bundled bar anchorages, even if equivalent area criterion seems to be slightly more conservative. The experimental results provide also information on the bursting forces generated by the wedge action of the ribs which clearly increases with bar diameter. Finally, experimental results are compared with design rules for anchorage strength of bundled bars as prescribed by fib‐Model Code 2010. [ABSTRACT FROM AUTHOR]

The paper presents an innovative method to determine anchor forces in anchor channels exposed to longitudinal shear loads. The channel's load‐bearing behavior is experimentally investigated by fiber‐optic techniques recording the longitudinal strains. For the first time these recordings uncover the inner flux of forces and enable to deduce the load distribution on the anchors. Before applying on anchor channels, the devices and components as well as its application are tested on a tension rod. Altogether 200 tests on anchor channels are performed varying the types of channel and anchor, the number of anchors, the closest distance of an anchor to the loaded edge and the position of load application. The tests confirmed that all available anchors (up to five were tested) transfer forces into the concrete member. Load distribution on the anchors is not uniform but depends on the type of anchor, the position of load application, the distance between the anchors and load application and the number of anchors available. By contrast, channel type and edge distance of the front anchor have little impact. [ABSTRACT FROM AUTHOR]

Three large-scale connections between square concrete-filled steel tubular (CFST) columns and H-section steel beams were tested. T-shaped vertical anchorage was used as the embedded elements and both static and seismic behaviours of the connections were tested in this study. The experimental parameters include length and location of T-shaped vertical anchorage. Based on the experimental data, the strength, ductility, stiffness degradation, and energy dissipation of the connections were calculated. The test results show that the connections exhibit good static and seismic behaviours. Furthermore, a parametric study was conducted using the finite element method where the considered parameters include the height and depth of end anchorage, and the thickness of vertical plate. Based on the study results, a preliminary design method is proposed, which includes the design formulae for calculating the thickness of vertical plate, the thickness of end anchorage, and the punching shear capacity of concrete. In conclusion, with a proper design, the connections with T-shaped vertical anchorage can be reliably used in practical applications. [ABSTRACT FROM AUTHOR]

The Red Sea is a deep rift between Africa and Asia, yet as an aquatic “highway” it links Europe to the Indian Oceanworld. While the existence of Greco-Roman trade down the Red Sea to the wider Eastern world is relatively well known, the harbors and destinations along the shores of the Red Sea are still being investigated. Understanding the geographical, and indeed geological, aspect of the sea is a key factor in the finding of ancient harbors and anchorages. Coupled with this is the need to discern the technology of maritime tools—navigation, ship-building technology, sailing practices—of the various eras and cultures of the Red Sea.This paper explores these aspects through the growing body of evidence and theory of Red Sea maritime endeavors, as well as the author’s own archaeological investigations in Eritrea and Saudi Arabia. [ABSTRACT FROM AUTHOR]

The technology of prestressing concrete structures has been a well‐established field in structural engineering since the last century. Nowadays, new materials developed for reinforcing concrete structures, such as fibre‐reinforced polymers (FRPs), open further possibilities for engineers. FRP tendons are more and more often investigated as an efficient and suitable material for prestressing, and there are already some field applications of this technology. This paper aims to describe the current state of knowledge in the field of prestressing with FRP tendons, with regard to available materials, developed anchorages and undertaken investigations. Researches conducted in areas such as bond strength, ductility, durability, long‐term behavior, and high‐temperature resistance are described and summarized. Our goal was to provide a summary of what has been achieved so far in the research field of prestressing concrete structures with FRP tendons; however, field applications and standardization issues are not part of this review. [ABSTRACT FROM AUTHOR]

Highlights • A total of 108 monostrand anchorages with different sizes and types were tested. • Several cases of cyclic amplitude, frequency and eccentricity were applied. • Measurement system captured the ultimate deformation reliably. • Early fractured of only one or few wires inside anchorages limited the capacity. • An analytical model of the anchorage behavior is proposed. Abstract Unbonded post-tensioning (PT) monostrands have traditionally been used in buildings to sustain monotonic loads on members subjected mainly to gravity loads. As a result, most of the technical information on commercially available unbonded PT anchorage systems focused only on applications for gravity-loaded members. Despite the recent experimental research efforts on the behavior of PT anchorages under earthquake-simulated demands, this information has not been well quantified in design documentation. Consequently, further research is needed on unbonded PT anchorages for their use in members subjected to seismic loads. This paper presents the results of a comprehensive experimental evaluation on the ultimate capacity of monostrand anchorages subjected to high-amplitude concentric and eccentric cyclic loads. In addition, this paper addresses the influence of anchorage type, loading patterns and strand size on the ultimate deformation capacity of these anchorages. Specimens consisted of monostrands assembled with anchorages at both ends. Two types of anchorages were tested. Moreover, seven-wire, uncoated, low-relaxation PT monostrands in two sizes were considered. Several cyclic loading conditions were applied, in order to evaluate the behavior of anchorages under different scenarios. The ultimate capacity of the specimens was dominated by a premature fracture of one or few wires inside the wedges and two types of wire fractures were recognized: (1) with little reduction in the wire cross-sectional area and (2) with a notable reduction in the wire cross-sectional area prior the fracture. It was also observed that increased number of wire fractures correlated with larger strain capacity in some specimens. In addition, it was observed that eccentric loads reduced the strain capacity by about 18% for eccentricities of 6% in some cases. The fracture of the specimens occurred at relatively small strains, with values as low as 1.4%. Therefore, strains in unbonded post-tensioned strands should be limited to about 1.0% when designing for seismic loads. Furthermore, an analytical model was proposed to evaluate the influence of anchorages in unbonded post-tensioning precast structures. [ABSTRACT FROM AUTHOR]

Highlights • Improved temperature dependent bond strength (TDBS) model was proposed. • Interface bond strength of GFRP laminates with heat-damaged concrete was estimated. • Experimental results on heat-damaged concrete was utilized for model development. • The results of TDBS model was verified by comparison with available solutions. • The proposed TDBS model showed high predictive capability. Abstract External bonding by the use of fiber-reinforced polymer (FRP) laminates to regain/improve the structural capacity of damaged/undamaged concrete members is a widely used popular method among various other retrofitting and strengthening techniques. A partial or full damage of concrete members due to accidental fire – that is at elevated temperature – often leads to significant reduction in the strength of concrete. The strength of such heat-damaged concrete structural members may be improved partly by the application of FRP composites – either by wrapping as whole or bonding locally on external surfaces. Both require understanding of the bond characteristics of FRP laminates with heat-damaged concretes. In this study, an improved temperature dependent bond strength (TDBS) model has been developed for predicting anchorage strength of glass fiber-reinforced polymer (GFRP) with heat-damaged concrete using the experimental results available from single-shear tests. The efficacy of proposed model in predicting the experimental values of interface bond strength of GFRP laminates with heat-damaged concrete has been critically shown by comparing the solutions from this study with other models reported in literature. A method for determining the debonding strain of FRP has also been discussed. [ABSTRACT FROM AUTHOR]

Large diameter bars and high reinforcement ratios – part 1: anchorages and laps According to Eurocode 2, large diameter bars > ∅ 32 mm may only be positioned taking additional rules into account. In contrast, the proposal for Eurocode 2 does not include any additional rules for large diameter bars. The additional rules were investigated with ∅ 40 mm reinforcing bars within two comprehensive experimental investigations at three institutes. After the investigation of ∅ 40 mm reinforcing bars, tests with ∅ 28 mm bars were also conducted to find the connection to conventional bar diameters. This article describes the experimental bond tests conducted at RWTH Aachen University that comprised beam‐end tests, four‐point bending tests with laps and end anchorages in simply supported beams. The test results are used to relax some additional rules. In the following, different design approaches are analysed with a database evaluation for the maximum steel stress to be developed in anchorages and laps. The design approaches for the calculation of necessary anchorage and lap lengths were compared on the basis of a database. [ABSTRACT FROM AUTHOR]

The paper presents experimental results on lap splices in Fiber Reinforced Concrete (FRC). Several full-scale beams reinforced with rebars of different diameters were tested with all or part of the longitudinal reinforcement lap spliced at mid-span. A traditional volume fraction of hooked steel fibers (equal to 0.5%) was adopted for FRC. Experimental results show that the toughness of FRC can enhance the behavior of the weak joint with only part of the rebars lapped at the section. The capability of FRC to control the flexural and splitting crack opening and propagation can increase the strength of staggered lapped splices, thus allowing a reduction of lap length. [ABSTRACT FROM AUTHOR]

This research explores the experience of mundane welcome and elaborates the emergent concept, ‘hospitality life politics’ (HLP), referring to hospitality practises invoked by the individual in order to negotiate the world on a day-to-day basis. Themes emerging from the ethnographic study are presented: sense of welcome; welcome habitus; ontological search for trust and security; welcome anchorages; the welcome assemblage; welcome as social oil; non-welcome; HLP as agency. Consideration is given to the theoretical implications of HLP, and the possibilities of hospitality in terms of creating healthy societies and its important role in advancing understandings of tourism. [ABSTRACT FROM AUTHOR]

Within the illegal urban settlements, called colonias populares, on the outskirts of Mexico City, the population’s anchorage does not seem obvious. This notion examines the circulation of individuals and their families in the different spatial and temporal scales of the living space. The analysis of the connections between people and their neighborhood highlights the role of residential context as a place of resources. From an empirical work and official surveys analysis, this paper aims to identify the different configurations of the places system on which inhabitants anchorages are built within the city. First, the links to their neighborhood in terms of practices allow to understand the space used in order to access to urban resources. Then, economic and social functionalization of the area is highlighted. In the end, crossing different practices of local and metropolitan areas allows the discovery of several types of links within the neighborhood and a variety of anchorages that fit into these places. Thus, the daily mobility underlines the urban resources existence, but also a relative intensity of movements on other scales, highlighting an integration process with the rest of the city.

The presence of supplementary reinforcement, in the form of edge reinforcement and stirrups, has a significant influence on the load-bearing capacity of anchorage groups with multiple anchor rows loaded in shear perpendicular to the edge. The current models available in the codes and standards are conservative for low to medium amounts of supplementary reinforcement but tend to be unsafe for high amounts of reinforcement. This paper presents the results of a comprehensive test program carried out to investigate the behavior of anchor groups with supplementary reinforcement loaded in shear toward the edge. The test results are discussed in detail to highlight the influence of supplementary reinforcement on the load-bearing capacity of the anchorages. Based on the evaluation of these test results, a realistic and rational model has been developed to predict concrete edge failure loads for anchorages with supplementary reinforcement that will be presented in another paper. [ABSTRACT FROM AUTHOR]

The mechanical impact of using segmented or continuous U-wrap CFRP sheets with varying lateral extensions to anchor CFRP strips, attached to steel-corroded reinforced concrete beams, was investigated. Control, corrosion-damaged, and corroded and repaired beams were tested under four-point loading for mechanical performance and CFRP-concrete bond behavior and their characteristics. The anchorage configuration, which involve bonding double layered CFRP sheets above and beyond CFRP plates at an extension of 100 mm to the beams’ soffit, had contributed the best towards promoting the flexural performance of corroded beams as load capacity and stiffness were increased by 37% and 54%, respectively, without harmful reductions in ductility and stiffness. Attaching 300-mm-long CFRP sheets to the free ends of the strips with lateral extension of 50 mm to beams’ soffit imparted the best second improvement in mechanical behavior. Comparison between intact-strengthened and corrosion-damaged and repaired beams revealed that corrosion cracking tended to significantly undermine the efficiency of present anchorage in improving mechanical response of repaired beams. The preset findings revealed that the benefit of concrete cover replacement prior to repair with CFRP composites was limited. [ABSTRACT FROM AUTHOR]

Steel column bases in seismically braced frames and other similar structures must be designed for high uplift or tensile forces. A common detail for this connection involves anchors embedded in the footing with a plate at their lower end, also embedded in the footing. This detail is increasingly prevalent in construction practice because it is exempt from the strength calculations of ACI 318 Appendix D. However, no experimental data or validated design guidelines are available to support the design of this detail. As a consequence, approaches from other similar situations (such as punching shear of slabs) are adapted for this purpose. To address this practical need, this paper presents tension tests on two full-scale specimens featuring this anchorage detail. The main variable examined in the experiments is the embedment depth, such that two depths (12 and 18 in.) are tested. The test specimens exhibit a classic concrete failure cone extending upward from the edges of the embedded base plate. The experimental data provide evidence that the anchorage detail provides an effective means to carry high-tensile loads. The data are evaluated against three strength models, including the ACI 318 Appendix D method, the ACI 318 punching shear equation and the concrete capacity design (CCD) method. It is determined that the ACI 318 Appendix D method is significantly conservative (average test-predicted ratio of 1.34) because it does not consider the beneficial effects of the embedded plate. On the other hand, the punching shear method has an average test-predicted ratio of 0.62. The CCD method shows the most promise, with an average test-predicted ratio of 0.99. Limitations of the study include the small size of the test set and the minimal reinforcement in the specimens. [ABSTRACT FROM AUTHOR]

The CFRP composite materials due to their excellent mechanical properties are more often used in civil engineering. In recent more than ten years has been observed e.g. much wider application of CFRP strips in structural strengthening. The research on this subject clearly showed the advantages of prestressed strips application in contrast to passive one. The CFRP utilization is much more effective in terms of strength and economy. However, the system effectiveness depends on reliability of anchoring used for prestressed strips. The main goal of the research presented in the paper was to develop a new, innovative, effective and reliable anchoring system for CFRP strips. The achievement of quite high carrying capacity of new anchorages was able thanks to combining friction, bonding and rivet clamping in one CFRP-steel joint. The research results revealed the effectiveness of new anchoring system with carrying capacity level of about 70% of the CFRP ultimate tensile strength.

This paper presents the results from an experimental investigation into the role that anchor selection, setting arrangement, and stretch length have on the post-yield behavior, rotation capacity, and ultimate strength of column baseplate connections. Eight full-scale column baseplate connections were designed to promote anchor yielding and tested under quasi-static, reversed cyclic loading. The connections utilized cast-in headed bolts, adhesive anchors, undercut anchors, two different types of setting arrangements, and a range of stretch lengths. The performance of the connections was evaluated by comparing their cyclic moment-rotation behavior, kinematics, and physical damage to the connection components. Anchor type, material selection, and the method used to level the column were found to have pronounced impact on the strength and rotation capacity of the connection. Increased stretch length was associated with only moderate increases in connection rotation capacity. In addition, a numerical model is presented and shown to very reasonably capture the salient response characteristics of the various tested connections. [ABSTRACT FROM AUTHOR]

The aim of this study is to enhance our understanding of anchorage capacity in reinforced concrete structures with corrosion-induced cover spalling. Our objectives were to study the influence of corrosion-induced cover spalling on bond strength, and to validate an existing one-dimensional (1D) analysis for anchorage capacity in such cases. Thus, earlier developed bond and corrosion models suited for detailed three-dimensional (3D) finite element (FE) analysis were first combined with a new computation scheme to simulate corrosion-induced cover spalling. The 1D and 3D FE analyses were validated through two types of experiments, i.e. eccentric pull-out tests and beam tests, as well as a comparison with an existing empirical model. The application of 3D FE analysis showed that the corrosion of stirrups advances the emergence of cracking and spalling, while bond strength is only slightly influenced by the corrosion of stirrups after cover spalling if yielding of stirrups has not taken place. Moreover, it was shown that stresses in the stirrups due to corrosion in adjacent bars rapidly diminished within a short distance from the main bar, and that the corrosion of stirrups influenced the shear capacity more prominently than the induced stresses in stirrups due to the corrosion of main bars. [ABSTRACT FROM PUBLISHER]

This work aims to evaluate the efficiency and reliability of two Non-Destructive Testing (NDT) methods for damage assessment in bridges’ anchorages. The Acousto-Ultrasonic (AU) technique is compared to classical Ultrasonic Testing (UT) in terms of defect detection and structural health classification. The AU technique is firstly used on single seven-wire strands damaged by artificial defects. The effect of growing defects on the waves traveling through the strands is evaluated. Thereafter, three specimens of anchorages with unknown defects are inspected by the AU and UT techniques. Damage assessment results from both techniques are then compared. The structural health conditions of the specimens can be then classified by a damage severity criterion. Finally, a damaged anchorage socket with mastered defects is controlled by the same techniques. The UT allows the detection and localization of damaged wires. The AU technique is used to bring out the effect of defects on acoustic features by comparing a healthy and damaged anchorage sockets. It is concluded that the UT method is suitable for local and crack-like defects, whereas the AU technique enables the assessment of the global structural health of the anchorage zones. [ABSTRACT FROM AUTHOR]

Modern composite materials, made on the basis of non-metallic continuous fibers are increasingly used in civil engineering, in particular to strengthen building structures. In strengthening of RC structures the utilization of externally bonded FRP composites is only up to 35% because of the pilling-off failure mechanism. This problem can be solved by the use of pre-tensioned composite laminates. Due to more complex behavior, the strengthening of structures using prestressing technology needs a careful design approach and a full understanding of the behavior of both the materials and elements. The advantages and risks of the presented technology, which may determinate the success of the entire project, are highlighted in the article. [ABSTRACT FROM AUTHOR]

Recent problems with grouted posttensioning tendons in U.S. bridges have led to interest in tendons that are not grouted, but rather filled with a pliable corrosion protection system such as grease or wax. The use of a flexible filler material in place of cementitious grout results in an unbonded tendon, which not only affects the structural behavior but also enables the application of new methods for improved monitoring and maintenance. This paper outlines a novel continuous monitoring approach that aims to detect wire breakage in unbonded tendons based on relative strain variation in the anchor head (or wedge plate). The feasibility of the method is investigated using a finite-element model calibrated with experimental data from a seven-strand anchor head. The model is subsequently extended to a 19-strand anchor head to assess the method's performance on detection, localization, and quantification of tendon damage. The numerical results confirm the correlation between wire breakage and relative strain variation among the monitoring points and illustrate the method's effectiveness in determining the location and severity of damage. [ABSTRACT FROM AUTHOR]

This paper investigates the use of glass fiber reinforced polymer (GFRP) bar bents as stirrups at the joint between the steel posts of a bridge guardrail system with a deck slab cantilever. In addition, GFRP bars with headed ends are used for better anchorage at the postdeck slab joint. Four full-scale cantilever post specimens were erected and tested to collapse. Two specimens were reinforced with steel bars as control specimens, whereas the other two specimens were reinforced with GFRP straight bars, bent bars, and headed bars at applicable locations. Similar failure modes were observed in all specimens because of curb external side face breakout. Failure occurred in unconfined concrete cover because of significant compressive and frictional shear stresses and also torsional effects, resulting in concrete spalling at the side face of the cantilever at the bottom of the posts. Although it is recommended to consider larger edge distance of the post to prevent premature failure in the unconfined concrete cover, the obtained experimental capacity of the postcurb region was concluded to be sufficient to resist design loads. To calculate the share of the design lateral loads received by each post, a linear finite-element analysis (FEA) and a simplified FEA were used. The analysis showed that the share of each post decreases with decrease in spacing between posts. [ABSTRACT FROM AUTHOR]