Anchor Elements Research Articles

Influence of cure time, temperature, and moisture on mechanical properties of a fast cure adhesive for post-installed rebar application

The use of chemical adhesives to post-install rebars and anchor elements in existing concrete structures has been widely developed in the previous years. The progress of the adhesive market in civil engineering has led to various commercialized structural adhesives targeting post-installation of steel elements in existing concrete structures. Regardless of the diversity of chemistries of adhesive types on the market today, existing mechanical theoretical descriptions and product evaluation methods are common to all adhesives.This paper presents the influence of moisture, cure time and temperature on the tensile behavior (resistance and stiffness) of a fast cure industrial adhesive used for post-installed rebar application. Results are compared to other studies on slow cure (epoxy) adhesives also used for the same application. The influence of temperature of the initial cure exothermic reaction is quantified through thermal measurements. Tensile tests performed at different times with samples stored at 50 % RH and 100 % RH show increase of strength and stiffness with cure time and highlighted the weakening effect of water. Finally, tensile tests performed directly at high temperatures (50 °C, 80 °C and 110 °C) on samples that had been previously pre-heated at these same temperatures or below were performed. Material strengthening caused by thermally induced post-cure (as observed for step polymerized products designed for the same application) is not distinguishable for the fast-cure adhesive. The progressive decrease of strength and stiffness with temperature appears unchanged by the thermal history.

Multivariate Analysis-Suitable T-Splines of Arbitrary Degree

Abstract This paper defines analysis-suitable T-splines for arbitrary degree (including even and mixed degrees) and arbitrary dimension. We generalize the concept of anchor elements known from the two-dimensional setting, extend existing concepts of analysis-suitability and show their sufficiency for linearly independent T-splines.

Use of Corrosion Inhibitors in Stainless Steel Anchors Used In Glass Fiber Reinforced Concrete (GRC) Precast Facade Elements

Corrosion is the process of losing the physico-mechanical properties of the metallic material over time as a result of chemical or electrochemical reactions. It is one of the most fundamental problems encountered in the construction industry; according to the latest research despite all the precautions taken corrosion causes an economic loss of approximately 546 million pounds per year. In addition to financial consequences, numerous dramatic damage events are directly or indirectly attributed to the corrosion process. Revealing the corrosion risk at the architectural design stage, taking into account the compatibility of the materials to be used, will contribute significantly to the steps to be taken regarding the monitoring and prevention of corrosion. In this study; the benefit of preventing the corrosion that occurs over time in the stainless steel anchors used in glass fiber reinforced concrete (GRC) precast facade elements by using corrosion inhibitor before mounted to the GRC was investigated. Creating a protective layer on the metal surface by using a patented chemical solution containing a corrosion inhibitor was used for the first time in the GRC sector in this study. After washing with corrosion inhibitor solution, stainless steel anchor elements were immersed in 5%(w/v) NaCl solution. After 30 days, the metal surfaces were examined by visually and were investigated by surface imaging methods (Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS)) and Atomic Force Microscopy (AFM). The findings show that washing with a solution containing corrosion inhibitor, especially after welding; increases the strength of the oxide film formed on the stainless steel surface and protects it against corrosion.

Corrosion behavior of embedded pad hook in glass fiber reinforced concrete

AbstractGlass fiber reinforced concrete (GFRC) comprises of hydration products of cement or cement plus sand, and glass fibers which take part in the concrete as reinforcement characteristics. GFRC has been used for over 50 years in several construction elements, such as facade panels, decorative no recoverable formwork, and other products. However, various anchor elements and pad hooks are needed to attach large or small parts made of GFRC panels to the main structure of the buildings. The corrosion rate of embedded metal fasteners over time is related to the water impermeability properties of the GFRC elements. In this study, corrosion of an electro galvanized pad hook embedded in 10–20 mm of the GFRC panel was investigated as a result of the salt spray test performed in accordance with ASTM B 117 standards. At the end of the experiment, the embedded pad hook was taken from the GFRC and analyzed by scanning electron microscopy, energy‐dispersive spectroscopy methods. The results showed that the embedded pad hook in the GFRC, which was examined in the test procedures comply with the TS EN 12467 standards, was not corroded by 120‐h test carried out in accordance with ASTM B 117 standards.

The Kalamoon University Campus: An oasis in the desert

The university campus built in the desert and semi-desert zone in countries with a hot climate is becoming important not only for the sustainable urban development of the region, but also for solving global problems associated with climate change and reducing carbon footprint. The article discusses the history of the creation of the campus of the private Kalamoon University in Syria, which shows how the university has an impact on the urban development of the city of Deir Atiyah and the surrounding areas. Against the backdrop of a difficult geopolitical situation, the Kalamoon University Campus has become an “oasis in the desert” and currently represents a modern university architectural and landscape complex with a comfortable and accessible environment, which is an example of effective development of territories in a hot climate, as well as one of the “anchor elements” of the urban planning system of the Al-Kalamoon region.

A comparative analysis of the corrosion characteristics of electro-galvanized steel coated with epoxy zinc-free and zinc-rich coatings in 5% NaCl

Anchor elements and pad hooks are used to attach large or small parts made of Glass Fiber Reinforced Concrete (GFRC) panels to the main structure of a building. The protection of these metallic parts is important to avoid corrosion. This work aims to compare the protection ability of normal epoxy and zinc-rich coatings (96% Zn) against chloride-induced corrosion of GFRC electrogalvanized pad hooks. The ASTM B117 salt spray test methods supported by SEM and EDAX surface analysis were adopted. The influence of surface treatment on coating thickness and performance was also considered. The results obtained show that the normal epoxy coatings are unsuitable for the studied pad hooks. Corrosion progressed under the coatings. Surface pre-treatment has a significant effect on the thickness of coatings. The average thickness of a two-coats untreated, sandblasted, and wire brushed pad hook zinc-rich coated layer is 39.27 µm, 117.8 µm, and 228.2 µm. The sandblasted pad hooks coated with zinc-rich coatings exhibit high corrosion resistance after the salt spray test. The EDAX results reveal that the surface products on the sandblasted zinc-rich coatings were devoid of the main substrate components, namely Fe, Si, and Mn but consisted of 2.43 wt.% O, 0.53 wt.% Cl, and 96.49 wt.% Zn. The absence of these elements implies no corrosion and effective corrosion prevention by zinc-rich coatings. Visual observation and SEM images corroborate the EDAX results. However, the thickness of the sand-blasted zinc-rich coated surface increased from 117.8 µm to 306.2 µm due to the formation of ZnO. Zinc-rich coatings are recommended for the protection of GFRC electrogalvanized hooks and elements.

Comparative analysis of the effectiveness of the combined method of inserting pedicle screws with the free-hand technique in patients with idiopathic scoliosis

Objective. To analyze intraoperative data and results of treatment of patients with idiopathic scoliosis with two options of the open insertion of pedicle screws using the free-hand technique.Material and Methods. The data of 457 patients aged 16–35 years who underwent surgical treatment for idiopathic scoliosis by one surgeon were analyzed. In 236 patients (Group I), the screws were placed manually, and in 221 (Group II) – using power tool. The preparation of the canal for pedicle screws in both groups was performed using the free-hand technique. The correct position of the screws wasassessed intraoperatively using an image intensifier and neurophysiological monitoring. The duration of surgery and X-ray monitoring, blood loss, and the presence of intra- and postoperative complications were assessed.Results. In Group I, 4243 screws were inserted, and in Group II – 3978. The correct position of pedicle screws was recorded in 89.1 % of cases in Group I, and in 89.6 % of cases in Goup II. In Group I, the incorrect position of anchor elements was detected in 10.9 % of cases, and in Group II – in 10.4 % of cases. The number of screws re-positioned intraoperatively corresponded to the number of incorrectly positioned screws. There was a statistically significant difference in the volume of intraoperative blood loss and duration of surgery betweenpatients of both groups (p < 0.05).Conclusion. The development and active introduction of high-tech methods of surgical treatment of spinal deformities increase the number of interventions performed annually. The proposed combined method of surgical treatment seems to be optimal because manual formation of the canal reduces the risk of intraoperative complications, and the use of power tool during screw placement shortens duration of surgery and reduces blood loss.

Analysis‐Suitable T‐Splines of arbitrary degree and dimension

AbstractThis paper defines analysis‐suitable T‐splines for arbitrary degree (including even and mixed degrees) and arbitrary dimension. We generalize the concept of anchor elements known from the two‐dimensional setting, extend two existing concepts of analysis‐suitability and justify their sufficiency for linear independence of the T‐spline basis.

Region-action LSTM for mouse interaction sequence based search satisfaction evaluation

Mouse interaction data contain a lot of interaction information between users and Search Engine Result Pages (SERPs), which can be useful for evaluating search satisfaction. Existing studies use aggregated features or anchor elements to capture the spatial information in mouse interaction data, which might lose valuable mouse cursor movement patterns for estimating search satisfaction. In this paper, we leverage regions together with actions to extract sequences from mouse interaction data. Using regions to capture the spatial information in mouse interaction data would reserve more details of the interaction processes between users and SERPs. To modeling mouse interaction sequences for search satisfaction evaluation, we propose a novel LSTM unit called Region-Action LSTM (RALSTM), which could capture the interactive relations between regions and actions without subjecting the network to higher training complexity. Simultaneously, we propose a data augmentation strategy Multi-Factor Perturbation (MFP) to increase the pattern variations on mouse interaction sequences. We evaluate the proposed approach on open datasets. The experimental results show that the proposed approach achieves significant performance improvement compared with the state-of-the-art search satisfaction evaluation approach.

Machine learning-based models for the concrete breakout capacity prediction of single anchors in shear

Proper functioning and safety of anchor elements are decisive for the overall performance of a structural system. A possible failure mode for anchor loaded in shear is the concrete breakout failure. Concrete related failure mode poses a significant safety issue, since they may develop abruptly/brittle, without preceding signs of damage. Consequently, accurate prediction of the concrete breakout strength of anchors in shear is crucial. This study proposes two machine learning models — a Gaussian process regression (GPR) and a support vector machine (SVM) model — for predicting the concrete breakout capacity of single anchors in shear. To this end, experimental strength of 366 tests on single anchors with concrete edge breakout failures were collected from literature to establish the experimental database to train and test the models. 70% of the data were used for the model training, and the rest were used for the model testing. Shear influence factors such as the concrete strength, the anchor diameter, the embedment depth (technically the influence length), and the concrete edge distance were taken as the model input variables. The generated GPR and SVM prediction models yielded a determination coefficient R2 = 0.99 for both the training and testing data sets. Predictions from the developed models were compared to that of the other existing models (Eurocode 2, ACI 318 and Grosser) to validate their performance. The developed GPR and SVM models provided a better prediction of the experimentally observed shear strength, compared to the existing models. The predictions obtained from the GPR model are the most accurate, yielding a value of 5.6 mean absolute error when tested.

AN INNOVATIVE GROUND ANCHOR FOR DEEP EXCAVATIONS IN VIETNAM

Large excavation-induced deformation of the anchored wall due to the limitation of anchor rod capacity in thick soft soil strata remains a problem in a deep excavation. In this paper, the performance of an innovative anchor type, so-called Hotdog anchor, invented by Korean engineers is investigated using the numerical and field test methods for excavation in Southern Vietnam. For comparison, both hotdog and pack anchor types are introduced in the case study. Proof tests of anchors were also conducted to provide data for the simulation. Four layers of hotdog anchors with 12m-bond length and 40 cm-diameter are adopted to compare with 4 layers of 18m-bond length and 20cm-diameter pack anchors in a soft to medium clay layers (NSPT = 1 ~ 13). In numerical analysis, the soil behavior was simulated using the Mohr-Coulomb model. The plate and node-to-node anchor elements were adopted to model the diaphragm wall and the anchors, respectively. Results show that the hotdog anchors could provide the larger bearing capacity and so that decrease the required bond length as compared with the pack ones. Based on that a guideline for the adoption of hotdog anchor to deep excavations in thick soft soil deposit in Southern Vietnam was proposed.

Additive manufacturing and computed tomography of bio-inspired anchorage systems

Using additive manufacturing, computer-assisted models can be rapidly transformed into physical objects. When combined with X-ray imaging, minimally attenuating three-dimensional (3D) printed objects can allow for enhanced insight into soil processes, whether this is through the design of novel testing devices, prototypes or soil surrogates. In this study, this methodology is exploited to investigate the pullout mechanics of bio-inspired anchors. The purpose of this paper is twofold: (1) to demonstrate the value of the union of 3D printing and X-ray computed tomography (CT) technologies; and (2) to evaluate the effect of geometry on the pullout behaviour of plant root-inspired anchor elements. The results of the experimental investigations demonstrate how X-ray CT was used to effectively capture the evolution of soil behaviour during the uplift of three unique 3D printed prototypes. The analysis of the soil response was completed from both a global perspective, through an interpretation of the force–displacement data, and a local perspective, through an image correlation investigation of image sets at sequential displacement increments. The results provide insight into not only the means to design a more optimised anchor element, but also the efficacy of additive manufacturing-assisted X-ray tomography in investigating geotechnical problems.

THE 2012 EARTHQUAKE: AN ABACUS OF SURVEYS AND INTERVENTIONS IN MANTUA CHURCHES

Abstract. After the earthquake of 2012, the ecclesiastical heritage of Mantua was so damaged to render unusable many buildings. Especially churches show a higher vulnerability in relation to their architectural features. From a recognition after the seismic event, more that 40% of the churches of Mantua were damaged with different intensity. After the first phase of expeditious damage detection, a methodical analysis has allowed to know the real state of conservation of many architectures. The Diocese of Mantua commissioned to the Mantua Campus of Politecnico di Milano the survey and digital documentation of 25 churches differently affected by the seismic event. The goal of the survey was double: a) realize the documentation necessary for the shoring and protection of damaged structures; b) prepare the drawing for the following interventions on the buildings such as restoration, reconstruction and retrofitting. Five years after the earthquake, many interventions of those identified were completed and concluded. Numerically, 129 churches were damaged and, nowadays, 115 have been restored and now they are fully open. The paper aims to illustrate the operational criteria used in the survey activity and repair operations carried out in order to identify guidelines that can direct operators in cases of new consolidation measures. All these directions were based on this premise: for historic structures, it is appropriate to accept a level of awareness with seismic risk higher than for ordinary structure, rather than act in the manner contrary to criteria of preservation of cultural heritage. In these years, we tried to identify the forms of dependence between observed damages, construction types and the conservative state before the earthquake. The goal in fact is to understand the cause of the wide loss of ecclesiastic heritage. The reason can be searched in the unfamiliarity of construction practices, techniques and materials with earthquakes or the inability of existing building to resist the seismic stress because badly maintained. These two possibilities conditioned the repair choices applied on the churches. The interventions regard different techniques which were optimized not only to be applied on buildings damaged by the earthquake but also on those that gradually show the necessity of accommodation measures. It is important, in order not to miss the operational experience gained in these years, to maximize the economic resources deployed by focusing the results achieved and verify if the followed path has been consistent and, if not, adjust the direction followed. In summary, the solutions adopted are for example: ties and anchor elements, repair works on vaults with mesh and plaster, repair works on vaults with addiction of lightweight ribs; repair works on cracked vaults with wood, steel wedges and injections of natural hydraulic lime, filling in the gaps of the masonry structure to reduce vulnerabilities.

Orthologs, turn-over, and remolding of tRNAs in primates and fruit flies.

BackgroundTransfer RNAs (tRNAs) are ubiquitous in all living organism. They implement the genetic code so that most genomes contain distinct tRNAs for almost all 61 codons. They behave similar to mobile elements and proliferate in genomes spawning both local and non-local copies. Most tRNA families are therefore typically present as multicopy genes. The members of the individual tRNA families evolve under concerted or rapid birth-death evolution, so that paralogous copies maintain almost identical sequences over long evolutionary time-scales. To a good approximation these are functionally equivalent. Individual tRNA copies thus are evolutionary unstable and easily turn into pseudogenes and disappear. This leads to a rapid turnover of tRNAs and often large differences in the tRNA complements of closely related species. Since tRNA paralogs are not distinguished by sequence, common methods cannot not be used to establish orthology between tRNA genes.ResultsIn this contribution we introduce a general framework to distinguish orthologs and paralogs in gene families that are subject to concerted evolution. It is based on the use of uniquely aligned adjacent sequence elements as anchors to establish syntenic conservation of sequence intervals. In practice, anchors and intervals can be extracted from genome-wide multiple sequence alignments. Syntenic clusters of concertedly evolving genes of different families can then be subdivided by list alignments, leading to usually small clusters of candidate co-orthologs. On the basis of recent advances in phylogenetic combinatorics, these candidate clusters can be further processed by cograph editing to recover their duplication histories. We developed a workflow that can be conceptualized as stepwise refinement of a graph of homologous genes. We apply this analysis strategy with different types of synteny anchors to investigate the evolution of tRNAs in primates and fruit flies. We identified a large number of tRNA remolding events concentrated at the tips of the phylogeny. With one notable exception all phylogenetically old tRNA remoldings do not change the isoacceptor class.ConclusionsGene families evolving under concerted evolution are not amenable to classical phylogenetic analyses since paralogs maintain identical, species-specific sequences, precluding the estimation of correct gene trees from sequence differences. This leaves conservation of syntenic arrangements with respect to “anchor elements” that are not subject to concerted evolution as the only viable source of phylogenetic information. We have demonstrated here that a purely synteny-based analysis of tRNA gene histories is indeed feasible. Although the choice of synteny anchors influences the resolution in particular when tight gene clusters are present, and the quality of sequence alignments, genome assemblies, and genome rearrangements limits the scope of the analysis, largely coherent results can be obtained for tRNAs. In particular, we conclude that a large fraction of the tRNAs are recent copies. This proliferation is compensated by rapid pseudogenization as exemplified by many very recent alloacceptor remoldings.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2927-4) contains supplementary material, which is available to authorized users.

Transcatheter direct mitral valve annuloplasty with the Cardioband system for the treatment of functional mitral regurgitation.

Direct mitral valve annuloplasty is a transcatheter mitral valve repair approach that mimics the conventional surgical approach to treat functional mitral regurgitation. The Cardioband system (Valtech Cardio, Inc., Or-Yehuda, Israel) is delivered by a trans-septal approach and the implant is performed on the atrial side of the mitral annulus, under live echo and fluoroscopic guidance using multiple anchor elements. The Cardioband system obtained CE mark approval in October 2015, and initial clinical experiences are promising with regard to feasibility, safety and efficacy.

Introducing a true minimally invasive meshless and dissectionless anchoring system for pelvic organ prolapse repair.

The objective was to demonstrate the biomechanical properties, feasibility, and potential advantages over conventional techniques of this new anchoring device, NeuGuide™. We evaluated the pull-out forces required to pull the NeuGuide™ anchor elements from a uniform porcine ligament and a cadaver ligament. We also evaluated the function of the NeuGuide™ and the characteristics of the device for the establishment of verification evidence ensuring the reliability and feasibility of the device. We also evaluated the safety and performance of the NeuGuide™ procedure in female cadavers by palpating the sacro-spinous ligament in real time. We assessed the ability to deploy and fixate the anchor to the sacro-spinous ligament and to stitch the sutures from both sides of the vaginal apex to the cervix, without damaging the surrounding structures. All 12 anchors were inserted into the porcine ligament and the cadaver sacro-spinous ligaments successfully (mean pull-out force 34.13 ± 4.32 and 35.68 ± 9.28 respectively). None of the measured forces were below 20 N. No statistically significant difference was noted in the pull-out forces between the porcine and the cadavers (p = 0.60), between the two cadavers (p = 0.19) and between the right and left sacro-spinous ligaments. No abnormalities or malfunctions were noted in the functional performance of the device. Upon laparotomy, dissection of the cadavers revealed that the sacro-spinous ligaments were reached safely with no damage to the surrounding organs and tissues. This novel anchoring device (NeuGuide™) is aimed at facilitating a durable, easy, and short procedure for sacro-spinous ligament fixation with hypothetically fewer operative complications.

Test of Adhesion and Cohesion of Silicone Sealants on Facade Cladding Materials within Extreme Weather Conditions

This research was carried out as part of project MPO FR - TI4/332 – New Technologies of Bonded Facade Cladding with Anchor Elements with Increased Resistance to Corrosion.This contribution concerns tests carried out to investigate the tensile properties of silicone sealants for use with facade cladding materials. The experimental part of the research is aimed at ascertaining the technical properties of sealants via the cyclic alternation of extension and compression of test specimens in test moulds. For the tests, industrially manufactured neutral and universal silicones were chosen from three different manufacturers. The aim of the research was to discover any differences that might appear in their resistance against alternating maintained extension and compression of the specimens under extreme temperature conditions, i.e. a high temperature of (70+2) °C and a temperature simulating freezing, i.e. (-20+2) °C. The cladding material used was fibre-cement composite boards (known as Cembonit), ceramic and glass cement facade claddings.The result of the measurements taken is a summary in which effective and unsuitable combinations of sealants and test substrates are outlined. The main conclusion is the fact that it is not possible to responsibly choose a suitable material without taking appropriate measurements or having previous experience. A secondary conclusion to this article is the fact that there are significant differences between individual sealants in the results they provide in combination with specific cladding material.

ANATOMIZING ELECTRONIC TRANSPORT THROUGH SATURATED ALKANE MOLECULE WITH DISPARATE TERMINAL ELEMENTS

In this paper, we anatomized transport properties of butane belonging to the saturated alkane group ( C n H 2n+2) using three terminal anchor elements (nitrogen, oxygen and sulfur) in Trans configuration connected to gold electrodes, forming a two probe model. The transport properties of three variants of butane were investigated in terms of Transmission spectra, Eigenstates, I-V characteristics and differential conductance for different values of biasing voltage using Keldysh's non-equilibrium Green's function combined with semi-empirical extended Hückel theory. Amongst the three binding elements, Butane exhibited maximum charge transfer with sulfur, then with nitrogen and least with oxygen. The HOMO-LUMO gap for both nitrogen and Oxygen as terminal anchoring elements suggested that conduction was virtually impossible through Butane in particular cases. Nature of Ballistic current for butane anchored with sulfur is ideal for its applicability as nano-diode or resonant tunneling diodes (RTDs) in arena of quantum-electronics due to its strong coupling between the terminal atoms and carbon atoms of butane. The retrenching order obtained in terms of conductance is S > N > O anchored butane molecule which seemed in full confirmation with the results of Transmission spectrum and its Eigenstates and proved sulfur to be a promising binding element and can produce much better results in comparison to oxygen and nitrogen. This paper marked another step in the field of molecular electronics as the butane anchored with sulfur has characteristics in conjunction to the semiconductor junction diode.

In search of authenticity in historic cities in transformation: the case of Pingyao, China

In a historic city, physical setting determines the uniqueness of a place, and the social and cultural activities in the physical setting enrich its cultural value. Along with the demands of modernization, the development of heritage tourism facilitates urban conservation, but it also challenges the meaning of the ‘authenticity’ of a historic city. The case study of the Ancient City of Pingyao, China, illustrates the city was transformed via political changes, and the functions of the traditional anchor elements in its city centre shifted; yet, the sense of place, in the form of collective memory, remained in its anchor elements across generations. However, memorable events, either personal or collective, are eclipsed by the over-emphasis on authenticity in the tourist setting. If the priority objective of preserving a historic city is to continue the local way of life, it is important to approach the discourses of authenticity of a historic city from the settlement's integrity, including the authenticity in physical setting, tourist setting and sense of place.

Numerical models for the dynamic response of submerged floating tunnels under seismic loading

AbstractThe modeling of tethering elements of seabed anchored floating structures is addressed, with particular reference to the so‐called Archimedes Bridge (submerged floating tunnel, SFT) solution for deep water crossing; attention is devoted to the design solution encompassing slender bars as anchor elements. Two numerical tools are proposed: firstly, a geometrically nonlinear finite element (NWB model), developed in previous work, has been refined in order to capture the effect of higher flexural modes of anchor bars. Secondly, a 3D beam element, based on the classical corotational formulation (CR model), has been developed and coded. Both elements are implemented in a numerical procedure for the dynamic time domain step‐by‐step analysis of nonlinear discretized systems; seismic loading is introduced by generating artificial time histories of spatially variable seismic motion. An example of application of the NWB element is shown regarding the behavior of the dynamic model of a complete SFT. The model was subjected to extreme multiple‐support seismic loading. The seismic behavior is here illustrated and commented, especially in light of the effect of higher local vibration modes of the anchor bars. Finally, a comparison between the performances of the two modeling approaches is presented. Both harmonic and seismic excitations are considered in the test; the results justify the use of the simpler NWB approach, especially in the SFT design phase. Copyright © 2008 John Wiley & Sons, Ltd.