Anchor Block Research Articles

Fluid-structure interaction in straight pipelines with different anchoring conditions

This investigation aims at assessing the fluid-structure interaction (FSI) occurring during hydraulic transients in straight pipeline systems fixed to anchor blocks. A two mode 4-equation model is implemented incorporating the main interacting mechanisms: Poisson, friction and junction coupling. The resistance to movement due to inertia and dry friction of the anchor blocks is treated as junction coupling. Unsteady skin friction is taken into account in friction coupling. Experimental waterhammer tests collected from a straight copper pipe-rig are used for model validation in terms of wave shape, timing and damping. Numerical results successfully reproduce laboratory measurements for realistic values of calibration parameters. The novelty of this paper is the presentation of a 1D FSI solver capable of describing the resistance to movement of anchor blocks and its effect on the transient pressure wave propagation in straight pipelines.

Effect of solvent quality and chain density on normal and frictional forces between electrostatically anchored thermoresponsive diblock copolymer layers

Equilibration in adsorbing polymer systems can be very slow, leading to different physical properties at a given condition depending on the pathway that was used to reach this state. Here we explore this phenomenon using a diblock copolymer consisting of a cationic anchor block and a thermoresponsive block of poly(2-isopropyl-2-oxazoline), PIPOZ. We find that at a given temperature different polymer chain densities at the silica surface are achieved depending on the previous temperature history. We explore how this affects surface and friction forces between such layers using the atomic force microscope colloidal probe technique. The surface forces are purely repulsive at temperatures <40°C. A local force minimum at short separation develops at 40°C and a strong attraction due to capillary condensation of a polymer-rich phase is observed close to the bulk phase separation temperature. The friction forces decrease in the cooling stage due to rehydration of the PIPOZ chain. A consequence of the adsorption hysteresis is that the friction forces measured at 25°C are significantly lower after exposure to a temperature of 40°C than prior to heating, which is due to higher polymer chain density on the surface after heating.

Shear behavior of anchor blocks in externally prestressed concrete bridges

In externally prestressed concrete bridge structures, the prestressed tendons are connected with prestressed concrete bridges by anchors and deviators, which are prone to be destroyed by the extremely complex stress concentration, resulting in prestress loss. Therefore, reasonable and safe design of anchors and deviators is very important for externally prestressed concrete bridges. In this paper, six inverted T-shaped specimens that represent the anchor blocks are tested to evaluate the effect of shear span–depth ratio and longitudinal reinforcement ratio on the shear behaviour of anchor blocks. The crack patterns, relative displacement, strain of steel and concrete, ultimate loads and failure modes are investigated. The experimental ultimate loads are compared with the calculated results from two design methods. Results indicate that the shear-friction model of AASHTO LRFD can predict the ultimate load very well when the shear span–depth ratio is less than 0·5. Meanwhile, in predicting the yielding load of the ties, the strut-and-tie model of ACI shows agreement with tested values at relatively large shear span–depth ratio of 0·57 and 0·93.

The Role of Emission Layer Morphology on the Enhanced Performance of Light‐Emitting Diodes Based on Quantum Dot‐Semiconducting Polymer Hybrids

The influence of the morphology of quantum dot (QD)‐semiconducting polymer hybrid emission layers on the performance of quantum dot‐based light emitting diodes (QLEDs) is systematically investigated. Chemically grafted QD‐semiconducting polymer hybrids are fabricated by the ligand exchange procedure between CdSe/CdxZn1−xS QDs and a new block copolymer consisting of a carbazole‐based electroactive block with a low highest occupied molecular orbital level and a disulfide‐based anchor block. The performance of QLEDs with hybrid emission layers is compared with QLEDs utilizing QD‐only and physically mixed QD/polymer emission layers. It is shown that only in the emission layers formed by chemically grafted hybrids QDs are evenly distributed throughout the semiconducting polymer matrix. This leads to improved charge transport balance and suppressed photoluminescence quenching of QDs. As a result, hybrid QLEDs with the peak external quantum efficiency of 5.6% and the peak luminance of 21 707 cd m−2 which outperform the conventional devices with QD‐only emission layers are fabricated.

Push Force Analysis of Anchor Block of the Oil and Gas Pipeline in a Single-Slope Tunnel Based on the Energy Balance Method.

In this paper, a single-slope tunnel pipeline was analysed considering the effects of vertical earth pressure, horizontal soil pressure, inner pressure, thermal expansion force and pipeline—soil friction. The concept of stagnation point for the pipeline was proposed. Considering the deformation compatibility condition of the pipeline elbow, the push force of anchor blocks of a single-slope tunnel pipeline was derived based on an energy method. Then, the theoretical formula for this force is thus generated. Using the analytical equation, the push force of the anchor block of an X80 large-diameter pipeline from the West—East Gas Transmission Project was determined. Meanwhile, to verify the results of the analytical method, and the finite element method, four categories of finite element codes were introduced to calculate the push force, including CAESARII, ANSYS, AutoPIPE and ALGOR. The results show that the analytical results agree well with the numerical results, and the maximum relative error is only 4.1%. Therefore, the results obtained with the analytical method can satisfy engineering requirements.

Design, construction and erection of seawater intake system to establish a biofouling test facility

Large amount of seawater is used in coastal industries, like power generating plants, desalination plants and aquatic culture farms. A similar requirement exists in Department of Atomic Energy campus at Kalpakkam, Tamil Nadu, India. Seawater in large quantities is required for its nuclear power stations and desalination plants erected on the east coast of Bay of Bengal situated in southern part of India. Such seawater systems have biofouling problems. Hence a seawater intake system has been designed, constructed and erected so that virgin seawater will be available for biofouling studies that was proposed to be carried in a once through flow test facility. A major criterion for the test facility was that continuous supply of seawater should be available at the rate of 160m3/h. To meet this requirement, centrifugal pumps were installed at about 150m away from the shoreline and connected to an intake structure using 600m long, 355mm OD, high density polyethylene pipeline laid on the seabed. Details of site selection, options of construction methods, materials selection, pressure drop calculations, sizing of pipes and anchor blocks, stability of intake pipeline, deployment criteria and project cost and planning have been discussed in this paper.

Computational dynamic models and experiments in the fluid–structure interaction of pipe systems

Fluid–structure interaction is analyzed using 1D and 3D computational models and results from an experimental facility, where transient events are induced. The water-hammer phenomenon is modelled by a 1D model based on the method of characteristics and the COMSOL Multiphysics 4.3b, which uses finite element method to study the fluid structural interaction involved in a long pressurized pipe system with curves, expansion joints, anchor and support blocks and different rheological behaviour of the pipe material. Comparisons are made between the experimental data and the two numerical models, where the type of response of each model was enhanced, as well as the ability of each model to simulate real conditions.

Reconstruction of the “Old Bridge to the Island” Across the Váh River in Trenčín

The paper describes the design of the reconstruction of the “Old Bridge to the Island” in Trenčín, which spans the river Váh in the area of Kočkovský channel. It is a road, reinforced concrete, three-span, girder bridge. The cross-section consists of three main girders of 1.55 m height, that increase to 2.4 meters in the support regions. The axial distance of the main girders is 2.8 meters. The total span of the bridge is 112.1 meters (35 + 42 + 35.1 m). In the ground plan the bridge is a skew one with a 79° angle. The vertical grade of the bridge is a polygonal curve (arch). The current width of the bridge is 5.0 meters with 1.0 m footways on both sides. The expansion of the “Ostrov (Island)” recreational zone requested an extension of this bridge and hence its extensive renovation. A part of the proposed solution is a strengthening of the structure by external pre-stressing strands, reinforcement of the structure to shear, widening of the carriageway to 6.0 m, construction of steel footways for pedestrians and cyclists, the exchange of bearings, an extensive renovation and widening of the abutments and re-profiling of all surfaces on the bridge. The proposed steel footway will be 3.08 m wide for the cyclists and 2.33 m for the pedestrians. These walkways will be directly connected to the supporting bridge structure and will extend the width of the bridge by almost a double. The steel footways itself will be anchored to the RC structure by a transverse pre-stress through reinforced concrete anchor blocks. All proposed solutions are designed with the requirement of maintaining the traffic on the bridge during the entire period of reconstruction.

Strengthening of Garudchatti bridge after failure of Chauras bridge

Two continuous lattice steel truss bridges spanning 190m with subdivided top chord members were constructed on the same design across river Alaknanda at Dugadda and Srinagar, respectively, in Uttarakhand, India. Both bridges were similar in design and geometry having middle span of 110.0m and two end spans of 40.0m. Garudchatti bridge at Dugadda was constructed first and opened to traffic, but excessive vibrations and lifting of end supports under live load condition were observed. Construction of Chauras bridge at Srinagar started later, but it collapsed during casting of the deck slab due to buckling of one of its top chord compression members. Failure of Chauras bridge led to the serious concerns in the minds of people and technocrats about the safety of Garudchatti bridge also, because it was constructed using the same design of Chauras bridge. Therefore, it was decided to strengthen and carry out load testing of Garudchatti bridge before reopening to the traffic.In the present work analyses of Garudchatti bridge are presented to identify structurally unsafe members for most severe live loads given in IRC:6-2010 code, and recommendations for strengthening of the critical members. Finite element space frame analyses of the bridge were carried out using STAAD Pro. v8i software to find excessively stressed members beyond their permissible stress limit. The critical compression members were strengthened by welding additional channel sections. RCC anchor blocks were constructed to restrict lifting of end supports under live load. After strengthening, load testing of the bridge was performed to ensure the safety of the bridge. The bridge is now reopened for traffic.In the past a number of bridges have collapsed during load testing. In case of any shortcoming in the design or overloading during load testing, compression members of the truss may suddenly buckle and cause collapse of the bridge. Therefore, it is not advisable to load test steel truss bridges which do not have adequate margin beyond the service load condition.

Embedded EM Sensor for Tensile Force Estimation of PS tendon of PSC Girder

In this paper, an embedded EM sensor was researched to estimate prestressing force of PS tendon in PSC girder. Recent methodologies for managing prestressing force loss were staying on verifying a applying prestressing force under construction, namely the loss management can not be controlled after construction. To estimate the tensile force of PS tendon during lifetime of PSC girder, this research proposed a bobbin-type embedded EM sensor that can be embedded in PSC girder is designed and fabricated considering the shape properties of anchorage zone and sheath. To verify the proposed sensor, a small PSC girder test was performed. The embedded EM sensor was connected to a sheath and anchor block, and the concrete was poured. After curing, the change of the permeability of PS tendon under tensile forces of 200, 710, 1070, 1300kN was measured using embedded EM sensor. The permeability of PS tendon had decreased according to the increment of applied tensile force. Also it is confirmed that the change of permeability due to applied tensile force could resolve the applied tensile force values. As a result, proposed embedded EM sensor could be embed into the PSC girder and it could be used to estimate the tensile force variation during lifetime of PSC girder.

Using the Unit Force Method to Analyze Thrust Acting on Anchor Blocks Caused by Thermal Expansion Displacement of X80 Tunnel Pipelines

To restrict the thermal expansion displacement of X80 tunnel pipelines, anchor blocks are commonly designed and installed at entrances and exits of tunnels, which makes the anchor block design one of the most important issues. As well known, the key step for anchor block design is to calculate the thrust acting on the anchor block caused by the thermal expansion displacement. In this paper, an analysis method of the thrust is proposed, considering the effects of the vertical earth pressure, transverse horizontal earth pressure, internal pressure, temperature variation, and pipeline–soil friction. Using the condition of deformation compatibility and the hypothesis of stagnation point, the axial force of tunnel pipelines is derived by the unit force method. By combining the compatibility condition between the transition segment length of anchored side pipelines and the displacement of anchor blocks, the thrust acting on anchor block is derived. Using the analytical method and finite-element software, the results of thrust acting on anchor block of the X80 tunnel pipeline for a specific gas pipeline project are calculated and compared. The results show that the analytical results agree well with those determined by finite-element software, and the maximum relative error is only 2.9%. The parameter analysis of the thrust and displacement of anchor blocks is investigated, including the buried depth for anchored pipeline side, the pipeline–soil friction coefficient, the volume of anchor block, the block–soil friction coefficient, the soil reaction coefficient, and the buried depth of anchor block.

Influence of mussel aquaculture on the distribution of vagile benthic macrofauna in îles de la Madeleine, eastern Canada

AEI Aquaculture Environment Interactions Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AEI 6:175-183 (2015) - DOI: https://doi.org/10.3354/aei00123 Influence of mussel aquaculture on the distribution of vagile benthic macrofauna in îles de la Madeleine, eastern Canada Annick Drouin1,2,*, Philippe Archambault2, Brianna Clynick1,2, Karine Richer1, Christopher W. McKindsey1,2 1Institut Maurice Lamontagne, Fisheries and Oceans Canada, 850 route de la mer, Mont-Joli, Québec G5H 3Z4, Canada 2Institut des sciences de la mer, Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski, Québec G5L 3A1, Canada *Corresponding author: annick.drouin@gmail.com ABSTRACT: We examined spatial variation in the abundance of 4 benthic vagile species in a lagoon with blue mussel Mytilus edulis aquaculture (inside vs. outside of the mussel lease; among areas with 1 yr old, 2 yr old and harvested mussels; and with distance from mussel lines). American lobster Homarus americanus, Atlantic rock crab Cancer irroratus, common starfish Asterias rubens and winter flounder Pseudopleuronectes americanus were all at least 3 times more abundant in the farm area with 2 yr old mussels, where mussel fall-off is more frequent, than in areas outside of the farm or other areas within the farm. A strong association of lobsters with mussel line structures was observed, where most individuals were observed directly under the mussel lines, close to anchor blocks, in the areas with 1 yr old, 2 yr old and harvested mussels (58, 42 and 57%, respectively). Mussel farms influence the distribution of benthic macrofauna at a number of spatial and temporal scales, and this may be due to a number of mechanisms, depending on the species. An in situ experiment was done to separate the influence of anchor blocks and mussel fall-off on the distribution of lobsters, crabs, starfish and flounders. Results of the manipulative experiment highlighted the importance of shelter structures over a short-term period for lobsters, but not for the other 3 species. Conclusions from the observations and the manipulative experiment suggest that lobster distribution is a function of both physical structure and feeding opportunities, whereas the distribution of the other species was mainly due to trophic effects. KEY WORDS: Mytilus edulis · Homarus americanus · Cancer irroratus · Asterias rubens · Pseudopleuronectes americanus · Spatial variation · Environmental impact Full text in pdf format PreviousNextCite this article as: Drouin A, Archambault P, Clynick B, Richer K, McKindsey CW (2015) Influence of mussel aquaculture on the distribution of vagile benthic macrofauna in îles de la Madeleine, eastern Canada. Aquacult Environ Interact 6:175-183. https://doi.org/10.3354/aei00123 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AEI Vol. 6, No. 2. Online publication date: February 04, 2015 Print ISSN: 1869-215X; Online ISSN: 1869-7534 Copyright © 2015 Inter-Research.

A parametric study of anchored earth wall by finite element method

A parametric study using finite element method of analysis was undertaken to investigate the behavior of an anchored earth wall system supporting clay backfill. In this paper the effects of stiffness of reinforcing tendon, elastic modulus of backfill soil, elastic modulus of retained soil and anchor size on the behavior of the wall system are presented. It was observed that deformation of wall decreases with increasing stiffness of reinforcement and above certain value of stiffness it has no effect on deformation. Most important finding was that coefficient of lateral earth pressure depends on the stiffness of reinforcement. For extensible reinforcements (axial strain > 1%), coefficient of lateral earth pressure is less than that of an active pressure condition. Deformation decreases with increasing stiffness of backfill and retained soil. Anchor force also decreases with increasing stiffness of backfill but remains constant with the variation of stiffness of the retained soil. It was also concluded that anchor block may be designed for a factor of safety of 2 or more.

The Effect of Anchor Test Construction on Scale Drift

In common-item equating the anchor block is generally built to represent a miniature form of the total test in terms of content and statistical specifications. The statistical properties frequently reflect equal mean and spread of item difficulty. Sinharay and Holland (2007) suggested that the requirement for equal spread of difficulty may be too restrictive. They suggested that an anchor test with representative content coverage and equal mean item difficulty but a smaller spread of item difficulty (miditest) may provide the same or better results for equating while decreasing the pressure to find very hard and very easy items to include in the anchor. Analyses to date have concentrated on the results of equating the scores from one form to another with findings that are supportive of the Sinharay and Holland concept (Sinharay & Holland, 2006a, 2006b, 2007; Liu, Sinharay, Holland, Feigenbaum, & Curley, 2009). These studies do not address longer chains of equating. It is important to monitor the possibility of scale drift over forms. The current research begins to address this issue.

One-pot synthesis of an inorganic heterostructure: uniform occlusion of magnetite nanoparticles within calcite single crystals

A facile one-pot method is described for the formation of novel heterostructures in which inorganic nanoparticles are homogeneously distributed throughout an inorganic single crystal matrix. Our strategy uses nanoparticles functionalised with a poly(sodium 4-styrenesulphonate)-poly(methacrylic acid) [PNaStS-PMAA] diblock copolymer as a soluble crystal growth additive. This copolymer plays a number of essential roles. The PMAA anchor block is physically adsorbed onto the inorganic nanoparticles, while the PNaStS block acts as an electrosteric stabiliser and ensures that the nanoparticles retain their colloidal stability in the crystal growth solution. In addition, this strong acid block promotes binding to both the nanoparticles and the host crystal, which controls nanoparticle incorporation within the host crystal lattice. We show that this approach can be used to achieve encapsulation loadings of at least 12 wt% copolymer-coated magnetite particles within calcite single crystals. Transmission electron microscopy shows that these nanoparticles are uniformly distributed throughout the calcite, and that the crystal lattice retains its continuity around the embedded magnetite particles. Characterisation of these calcite/magnetite nanocomposites confirmed their magnetic properties. This new experimental approach is expected to be quite general, such that a small family of block copolymers could be used to drive the incorporation of a wide range of pre-prepared nanoparticles into host crystals, giving intimate mixing of phases with contrasting properties, while limiting nanoparticle aggregation and migration.

The interfacial structure of polymeric surfactant stabilised air-in-water foams

Small-angle neutron scattering was used to probe the interfacial structure of nitrogen-in-water foams created using a series of tri-block polymeric surfactants of the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (EOx-POy-EOx) range, from which the nature of the polymeric interface could be characterised. The data follow a pronounced Q(-4) decay, along with a number of inflexions and weak but well-defined peaks. These characteristics were well-described by a model embodying paracrystalline stacks of adsorbed polymer layers, whose formation is induced by the presence of the air-water interface, adsorbed at the flat air-water (film lamellae) interface. A minimum of approximately five paracrystalline polymer layers of thickness of the order of 85-160 Å, interspersed with somewhat thicker (400 Å) films of continuous aqueous phase were found to best fit the data. The thickness of the layer (L) was shown to follow a relationship predicted by anchor block dominated polymer adsorption theories from non-selective solvents, L ∼ EO(1)PO(1/3). The insight gained from these studies should permit a more rational design of polymeric stabilisers for hydrophilic polyurethane foams.

Predicting the seismic behaviour of the foundations of the Messina Strait Bridge

This paper presents some of the geotechnical studies carried out for the seismic design of the one-span suspension bridge across the Messina Strait, that is to connect Sicily with mainland Italy. These studies included advanced geotechnical characterisation, through in situ and laboratory tests, estimate of site stability involving both liquefaction analysis and submerged slope stability, evaluation of soil-foundation stiffness for spectral analysis of the superstructure, 3D FE static calculations, evaluation of anchor block performance under seismic conditions, and full dynamic analyses of the soil–structure interaction. The paper summarises the main results obtained from the geotechnical characterisation of the foundation soils, reports the approach adopted for evaluating the seismic performance of the anchor blocks through a modified Newmark-type calculation, and presents the study of the soil–structure interaction carried out through a series of two-dimensional, plane strain numerical analyses. In these analyses, in addition to the embedded foundation elements, the models included a simplified structural description of the bridge towers specifically designed to reproduce their first vibrations modes, that were deemed to have the most significant influence on the system’s dynamic response. The illustration is limited to the foundation systems of the bridge located on the Sicily shore.

Polyacrylonitrile Block Copolymers for the Preparation of a Thin Carbon Coating Around TiO2 Nanorods for Advanced Lithium‐Ion Batteries

Herein, a new method for the realization of a thin and homogenous carbonaceous particle coating, made by carbonizing RAFT polymerization derived block copolymers anchored on anatase TiO2 nanorods, is presented. These block copolymers consist of a short anchor block (based on dopamine) and a long, easily graphitizable block of polyacrylonitrile. The grafting of such block copolymers to TiO2 nanorods creates a polymer shell, which can be visualized by atomic force microscopy (AFM). Thermal treatment at 700 °C converts the polyacrylonitrile block to partially graphitic structures (as determined by Raman spectroscopy), establishing a thin carbon coating (as determined by transmission electron microscopy, TEM, analysis). The carbon-coated TiO2 nanorods show improved electrochemical performance in terms of achievable specific capacity and, particularly, long-term cycling stability by reducing the average capacity fading per cycle from 0.252 mAh g(-1) to only 0.075 mAh g(-1) .

PH-responsive poly(ether sulfone) composite membranes blended with amphiphilic polystyrene-block-poly(acrylic acid) copolymers

pH-responsive poly(ether sulfone) (PES) composite membranes blended with amphiphilic polystyrene-block-poly(acrylic acid) (PS-b-PAA) diblock copolymers are fabricated through simple phase inversion in water. The anchor block PS has a lower surface tension than that of PES, which is beneficial to anchor the PS block near the membrane pore surfaces. Modification of membrane matrix surface including membrane surface and pore surface by PAA chains is achieved by surface-segregation of PS-b-PAA copolymers, and confirmed by water contact angle measurement on membrane surface and confocal laser scanning microscopy characterization of membrane cross-section. The effects of the blended PS-b-PAA copolymers on the microstructures and pH-responsive characteristics of the PES composite membranes are investigated systematically. The hydraulic permeation results show that the pH-responsive characteristics of composite membranes blended with PS-b-PAA copolymers are proven to be significant, fast, reversible and durable with pH switching between 3 and 8. FITC-dextran sieving experiments of a PS-b-PAA blended composite membrane at ambient pH values of 3 and 8 show 28% and 90% rejection of 70kDa solute, respectively. At pH=3 (<pKa), the membrane pores are in “open” state because of the shrunken conformation of the PAA chains on the pore surfaces; in contrast, at pH=8 (>pKa), the membrane pores are in “closed” state due to the swollen conformation of the PAA chains. The results provide valuable guidance for fabricating stimuli-responsive membranes by blending amphiphilic block copolymers.

기초근가와 기존근가의 하중에 따른 변위 비교분석

In this paper, we compared and analyzed for safety 1.2m rectangular anchor block and arch-type root anchor block. First, numerical analysis was performed three-dimensional nonlinear method by numerical model test using finite element analysis program Visual FEA. Then, measure displacement of the surface of the earth after construct each anchor block at 14M electric pole and increase loads through field verification tests for safety evaluation.