2: 431. PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362. Table 32.2 . Instruction, in order to justify the fact that the steel complies with the requirements laid down in Significant features of this mechanical device are 1) the CFRP sheets are directly anchored to the device itself; 2) prestressing is easily achieved while the device is . 3 is a perspective view of a work table of a mechanical finishing device with a prestressing device in accordance with the present invention; FIG. of any possible surface defects. The stress interaction mechanisms are demonstrated in, Although it is demonstrated that there is a constant decrease in terms of the interface bonding strength, the mechanical performance shows that the maximum prestress benefits in terms of flexure modulus and impact strength occur at the same optimal prestress level with the tensile strength, i.e., 90 MPa of creep stress. mm does not include the failure section nor any zones affected by a possible stricture, this is known as the distributed Unbonded . An experimental program was conducted to check the validity and efficiency of the prestressing system by testing three reinforced concrete beams. less than 30 mm in a 1 m length at any point along the wire. use isolated wires (in other words, those that do not form part of strands) as prestressing reinforcement, that these As a consequence of this, 1999 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (Cat. Si 0.15 0.40 . transmission, geared transmission in conjunction with pulley blocks, screw jacks with or without gear drives and wire-winding machines. - The elongation at maximum load, measured over a base of length equal to, or [. Better quality control ; Weaver, P.M. Bistable Prestressed Buckled Laminates. Stage-II is the curing stage of EPPMC. The study focuses on the mechanical properties of prestressing steel at elevated temperatures and after cooling by employing the central core wire of prestressing strand. Although the EFP is active in improving the static mechanical performance of a composite, its mechanics on dynamic mechanical performance and viscoelasticity of a composite is still limited. In a situation of employing wires with very severe straightening requirements, as occurs in the manufacture https://www.mdpi.com/openaccess. To check the efficiency of the prestressing system, two reactive powder concrete curved slab members were cast and tested under a uniformly distributed load. Chen, H.; Yu, F.; Wang, B.; Zhao, C.; Chen, X.; Nsengiyumva, W.; Zhong, S. Elastic Fibre Prestressing Mechanics within a Polymeric Matrix Composite. To check. When the prestressing is achieved by elements located inside the concrete member (commonly, by embedded tendons), it is called internal prestressing. have taken place. permission is required to reuse all or part of the article published by MDPI, including figures and tables. Thermomechanical testing was performed at a heating rate of 5 C/min until 200 C, with an amplitude of 2 m and frequency of 1 Hz. This relationship shall be met, not only by the minimum guaranteed values, Author to whom correspondence should be addressed. Studies have been made of the retardation of electrical tree growth in epoxy resin specimens using experimental pre-stressed reinforcing fibers. 4 is a perspective view of a column of a mechanical finishing device with a prestressing device in accordance with the present invention; FIG. Element Minimum percentage Maximum percentage. technical requirements established in UNE 36094:97. Experiments were carried out using an accurate testing system for the development of empirical formulae to predict the deterioration of prestressing steel at elevated temperatures and after cooling. 1) Initial : It can be subdivided into two stages. The inside diameter of the coil or after heating and cooling to room temperature). Typical values of span-to-depth ratios in slabs are given below. New Mechanical Engineering jobs added daily. ; data curation, F.Y. Although prestressing has advantages, some aspects need to be carefully addressed. The main findings include: The EFP technique is able to be applied to a UD carbon prepreg material through a bespoke fibre prestressing rig to produce prestressed composite samples. Ph.D. The aim is to provide a snapshot of some of the Shokrieh, M.M. Find a library where document is available. Suitable for use in pressure vessels, liquid retaining structures. We use cookies on our website to ensure you get the best experience. This can prevent the mechanical component from being bent or deformed when a large force is applied to the mechanical component. The maximum unit load fmax shall not be less than the values given in Table 32.5.a, in the Therefore, research into EPPMC mainly focuses on limited aspects of static mechanical analysis, and the prestressing mechanisms are derived based on restricted observations. ; funding acquisition, B.W. Pre-tensioning Export citation and abstract Effect of Tensile . External or internal prestressing The authors would like to acknowledge the financial support from the National Natural Science Foundation of China (52005108, 52275096, 51675103), Fuzhou-Xiamen-Quanzhou National Independent Innovation Demonstration Zone High-end Equipment Vibration and Noise Detection and Fault Diagnosis Collaborative Innovation Platform Project, Fujian Provincial Science and Technology Project (2019I0004), State Key Laboratory of Mechanical Systems, and Vibration (MSV-2018-07), Shanghai Natural Sciences Fund (18ZR1414200), as well as the Start-up Funding from Fuzhou University (GXRC-20066). Viscoelastically Prestressed Polymeric Matrix Composites: An Investigation into Fibre Deformation and Prestress Mechanisms. 1, the prestressing device (, When a huge force is applied to one distal end of the base (, With reference to FIG. ; supervision, B.W. Current Planning Division On-line Project Application. Stress induced by fibre prestressing is, thus. Mechanical properties of a unidirectional carbon prepreg before and after curing. The reinforcement should be stored correctly classed by type, class and lot of origin. Prestressing. performed on the steel (see Article 90) on acceptance, although test intensity will vary from one case to another. The sample dimensions were 20 8 0.4 mm, and the test span was 5 mm. - The yield stress fy shall remain between 75% and 90% of the maximum unit load A new, practical mechanical prestressing system was developed to prestress carbon-fiber-reinforced polymer (CFRP) sheets. percent. A prestressing device for a mechanical component of a mechanical finishing device has at least one rigid prestressing unit mounted in the mechanical component. 1) Section remains uncracked under service loads. We design and build bespoke stressing solutions for new and existing precast factories producing . No.99CH36319), Proceedings of the 3rd International Conference on Conduction and Breakdown in Solid Dielectrics, In order to study systematically the relationship between mechanical properties and tree initiation and growth, a range of mechanical properties was obtained by the plasticization of the original. on dimensions and qualities of bars, since this should be obtained from the actual producers themselves. This type of prestressing is adopted for mass scale production. The creep stress was set as 3 MPa, which is restricted by the DMA, and both creep and recovery were monitored for 30 min. Hence, it is not as common as reinforced concrete. All the results presented in the manuscript could be requested to the corresponding author. When the prestressing is achieved by elements located outside the concrete, it is called external prestressing. [. followed by a drawing process and another for stress-relieve. The earliest tests were carried out in France in 1940s on cold-drawn steel wires and reported by Guyon [ 3 ]. 2023; 15(2):431. Reduced maintenance Tie Rod Diameter Up to 3 " 3 -4" 4 -7" 7" & over. Feature Papers represent the most advanced research with significant potential for high impact in the field. Internal Prestressing Proceedings of the 2004 IEEE International Conference on Solid Dielectrics, 2004. Pang, J.W.C. If you do not see the project application you need or have any questions regarding these applications, please reach out to our Planner on Duty at (310) 253-5725 or (310) 253-5710. In the rubbery plateau region at 180 C, the prestress effects show a similar trend as with the glassy region and give a maximum improvement of 30.0% in flexure modulus. The prestressing device has at least one rigid prestressing unit mounted in the mechanical component to provide a prestressing tension to the mechanical component. Prestressing bar, similar to prestressing steel strand (wire), does not have a clearly demarked yield plateau at . Please let us know what you think of our products and services. case of 2- or 3-wire strands, and 32.5.b in the case of 7-wire strands. ; Schenk, M. Thermal Prestress in Composite Compliant Shell Mechanisms. 1973 012105 A manual mechanical prestressing system was manufactured which used to apply a post-tension force to the high-stress steel wires in the curved slab member. When the level of prestressing is such that the tensile stress under service loads is within the cracking stress of concrete, it is called Limited Prestressing (Type 2). Larger spans possible with prestressing (bridges, buildings with large column-free spaces) Higher moment of inertia (higher stiffness) Thus, a universal tensile machine MTS-CMT4104 was used to apply tension on unidirectional carbon prepreg to determine the tensile performance following ASTM D3039 [, A Charpy impact tester LX-XJJ-50 from Guangdong Aisry Instrument Technology was used for impact testing, with a pendulum impact energy of 15J. 2) Intermediate : This includes the loads during transportation of the To ensure stable and reliable fibre prestressing, the lower surface of the fixing clamp, the upper surface of the thermal plate and the upper surface of the roller, are kept on the same plane. Stacey, J.P.; ODonnell, M.P. Stage-I is the fibre prestressing stage, where constant tensile stress. To evaluate the effects of fibre prestressing, EPPMC samples under various fibre prestressing levels were produced, including 0 MPa, 12 MPa, 24 MPa, 48 MPa, 90 MPa, 135 MPa, 180 MPa, and 220 MPa. Tuttle, M.E. environments (sulphides, chlorides and nitrates), or which indicate the level of susceptibility to hydrogen brittleness. Strands:Two, three or seven wires are wound to form a prestressing strand. The established theoretical model indicates further insight and the EFP mechanisms are proposed to reveal the in-plane stress evolution, which is vital to determine the overall performance of the polymeric composite. The. Reduction in self weight Today's top 5,000+ Mechanical Engineering jobs in Culver City, California, United States. It is found that fibre prestressing is effective in destroying the defective fibres before being cured into a matrix, which in turn improves the mechanical strength of the polymeric composite. and C.Z. d) Concentrated residual strain at failure (eu). To produce an EPPMC, elastic fibres are prestressed at a designated level and impregnated in an uncured resin. relaxation. Uniaxial, biaxial or multi-axial prestressing Element Minimum percentage Maximum percentage . The elastic fibre prestressing (EFP) technique has been developed to balance the thermal residual stress generated during the curing of a polymeric composite. Measured stress-strain curves are used to verify the accuracy of the proposed model. Publishing. accordance with UNE 36461:80. Corrosion of reinforcing and prestressing steel due to chloride contamination is one of the primary causes of deterioration of concrete structures. Mechanical Prestressing System for Strengthening Reinforced Concrete Members with Prestressed Carbon-Fiber-Reinforced Polymer Sheets A new, practical mechanical prestressing system was developed to prestress carbon-fiber-reinforced polymer (CFRP) sheets. but also by the values corresponding to each of the tested bars. The bending and the deformation of the mechanical component can be prevented. Terms of Use and Privacy Statement, https://doi.org/10.1061/(ASCE)CF.1943-5509.0000478, Journal of Performance of Constructed Facilities. A mechanical device was invented for prestressing of carbon fiber reinforced polymer (CFRP) sheets. S -- 0.040 The tension is applied to the tendons (located in a duct) after hardening of the concrete. 5 is a perspective view of a tool-head stand of a mechanical finishing device with a prestressing device in accordance with the present invention; and. The prestressing of concrete has several advantages as compared to traditional reinforced concrete (RC) without prestressing. The study aims to experiment with the use of a mechanical prestressing technique of thin curved sections to assess the prestressed force influencing the behavior of a curved slab at the initial and final loading stages. The other fibre ends were attached on the weight platform in order to be prestressed. ; Hahn, H.T. The following figure shows the biaxial prestressing of slabs. This is the most important classification and is based on the sequence of casting the concrete and applying tension to the tendons. Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. Grade 1860 strands to. otherwise should contain a single produced length of strand. 1 is a perspective view of a base of a mechanical finishing device with a prestressing device in accordance with the present invention; FIG. The real Whenever it is possible to choose between various strands of differing wire diameters, under the same Part III: Effects of Thermal Residual Stresses. All Rights Reserved. It is therefore recommended that, whenever the existence of a ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:YEN, KELSON;HSU, CHEN-CHIEN;REEL/FRAME:011951/0428, Free format text: Force Measurement from Viscoelastically Recovering Nylon 6, 6 Fibres. tolerances shall conform to the specifications given in UNE 36094-2:97. - The failure stricture shall be visible to the naked eye. and S.Z. Tree growth is sensitive to, Proceedings of 1995 IEEE 5th International Conference on Conduction and Breakdown in Solid Dielectrics. Circularly prestressed containment structure, Kaiga Atomic Power 3) Final : It can be subdivided into two stages. Initial stress as a percentage of the maximum unit load fmax Relaxation. A dynamic thermomechanical analyser DMA1 (Mettler Toledo Group Ltd., Zurich, Switzerland) was used for three-point bending tests of the prestressed composite samples. CA1122766A CA166,712A CA166712A CA1122766A CA 1122766 A CA1122766 A CA 1122766A CA 166712 A CA166712 A CA 166712A CA 1122766 A CA1122766 A CA 1122766A Authority CA Canada Prior art keywords core pipe section gasket pipe section Prior art date 1972-03-31 Legal status (The legal status is an assumption and is not a legal conclusion. For the same span, less depth compared to RC member. The main features of the system are as follows: (1) the prestressing forces are applied manually without using hydraulic jacks, (2) the prestressing level of the CFRP sheets can be controlled by using an electronic load cell, (3) the system is light weight and can be installed without using heavy lifting equipment, (4) the CFRP sheets are extended to the ends of the member where high shear stresses occur, and (5) releasing of the prestressing CFRP sheets is accomplished under a slow strain rate. You are accessing a machine-readable page. The following classifications are discussed. 1.2.2 Advantages of Prestressing Viscoelastically Prestressed Polymeric Matrix Composites: An Overview. Now the internal stress level within the cured composite. 1. ; formal analysis, B.W. 36422:85, shall not be greater than 2%. Partial Prestressing. An Experimental Study of the Effect of Prestressed Loose Carbon Strands on Composite Strength. 3, the prestressing device (, With reference to FIG. * This value is the one required by the article. Now we consider the in-plane stress level (i.e.. Wang, B.; Fancey, K.S. [, EFP can also be applied to improve the impact resistance of PMCs [, For flexural performance, Motahhari et al. The system is used for strengthening reinforced concrete members. The minimum number of reverse bends that the wire should be capable of Fiber reinforced polymeric insulation materials are composite insulating materials that are made from high-performance polymeric insulation material and high-performance fibers. The mechanical properties of the prestressing bars, which are obtained from the tensile B Beam Interact. Uniaxial, Biaxial or Multiaxial Prestressing In the cases of both certified and non-certified products, the Instruction requires that quality control tests be mechanical specifications adopted for the project vary with temperature. According to the elastic fibre prestressing principle in. Electrical Prestressing To further understand the EFP mechanics, we established a theoretical model to decouple the EFP principle and performed a comprehensive investigation into the prestress effects in terms of the static and dynamic mechanical properties, as well as the viscoelastic creep performance. The first one is reinforced with micro steel fibers while the second one is reinforced with micro steel fibers in addition to four high-stress steel wires. Other Topics Pet Boarding Application to, Company has made additional purchase of fixed assets amounting to 187.61 crore it is out flow of cash for assets amounting to 187.61 crore it is out flow of cash for company and, As expected, the road racing helmet Lazer O2 with 24 air vents generates higher aerodynamic drag at all pitch angles (Head Positions 1, 2 & 3) compared to all other helmets.. The different types of prestressing steel are further explained. fmax. prior to publication. the drooping prevention head assembly of column transfering milling machine and the milling machine equipted with the head assembly, Device for correcting bending of a horizontal machine-tool support element, Side gap press and frame structure therefor, Machine frame, having a biased wire girdle, and a method for biasing such a girdle, Arrangement for prestressed assembly of machine and base-modules, Prestressed press framework for a papermaking machine, Part fixturing sysems having expanding clamping devices, One kind has shock-absorbing function pump industry production lathe for machining, Lathe processing is with effectual anchor clamps of antiskid, Arrangement, a fastening device, method and system for clamping a piece as well as a fastening clamp, Beam fixing gantry type numerical control machine, Material removal tool stiffened with spacers arranged along a length, Opposed handle hand tool with composite handle, Digit Control Machine Tool Remote Hydraulic drives bench vice, A anchor clamps for abnormal shape aluminum product cutting process, Mechanical device for spreading flanges apart, Method and device for manufacture of connecting rod, But adjustable support means of magnetic suppression automation line delivery sheet, Fixed beam gantry type numerical-control machine tool, Forging press with pre-stressed frame structure, Exempt to fill up combination center adjustable height lathe tool, Device and a method for holding together tool parts druing a hydroforming process, Deflection prevention device for arm in vertical lathe, Auxiliary pipe bending mechanism of pipe bending machine, Processing unit (plant) based on timber in wood packing box, Lapse for failure to pay maintenance fees, Information on status: patent discontinuation, Lapsed due to failure to pay maintenance fee. ]{n+c oE$A#n]~.\${,tKwn{q3 greater than 28 for strands with a nominal diameter equal to, or greater than, 13 mm. ; writingoriginal draft preparation, H.C., F.Y., B.W. - The modulus of elasticity should be guaranteed by the producer within a When the prestressed members are straight or flat, in the direction of prestressing, theprestressing is called linear prestressing. See further details. Composed piezotransducers submitted to mechanical pre-stressing present shifts on resonance and anti-resonance frequencies. The experimental program includes a tensile test, a fatigue test, a relaxation test, and a stress corrosion test. This is not to argue that electrical treeing is exclusively a mechanical phenomenon directly analogous to mechanical cracking. As the names suggest, the classification is based on the directions of prestressing a member. Knowledge of the mechanical properties of prestressing steel at elevated temperatures and after cooling is essential to the fire resistance design and post-fire evaluation of the residual load-carrying capacity of prestressed concrete structures. If the In wires having a diameter equal to, or greater than, 5 mm or equivalent in section, the progress in the field that systematically reviews the most exciting advances in scientific literature. When the prestressed members are curved, in the direction of prestressing, the prestressing is called circular prestressing. ; Kamangar, S.; Hussien, M.; Umarfarooq, M.A. For steel in possession of a recognised quality mark or a Certificate of Compliance with Here, we established a theoretical model in order to decouple the EFP principle, aiming to better analyse the underlying mechanics. We also thank the technical staff and aegis of the Fujian Provincial Key Laboratory of Terahertz Functional Devices and Intelligent Sensing @ Fuzhou University. Feature The terms are placed in groups as per usage. Bonded tendon: When there is adequate bond between the prestressing tendon and concrete, it is called a bonded tendon. %PDF-1.2 % Prestressing reinforcement shall be transported fully protected against moisture, An Affiliate Member of ASCE American Society of Civil Engineers. Pulse overvoltages can threaten working state of the, IEEE Transactions on Dielectrics and Electrical Insulation, Tensile and compressive stress, produced by the spring clamp device and the banding force after the expansion of silicone rubber stress cone, can affect the electrical properties of silicone rubber, Effects of mechanical stretching, produced after the expansion of cable accessories, on the electrical tree growth characteristics of EPDM (Ethylene Propylene Diene Monomer) are reported in the, In predicting electrical tree growth behaviour of practical insulation materials under operating alternating voltages, one must consider the effects of compressive and tensile residual stresses to, In this paper we develop a kinetic model for the growth of electrical tree structures in solid polymeric insulation that allows for combined electrical and mechanical stresses. The wires used in the strands shall be capable of withstanding the number of reverse Hammering is undoubtedly the oldest form of mechanical prestressing in the sense of stressing a metal beyond its yield strength. value may vary between 180 and 195 kN/mm depending on the production process. This type of of 7%. Fraile-Martnez, O.; Garca-Montero, C.; Coca, A.; lvarez-Mon, M.A. The useful life of the mechanical finishing device is prolonged. The tension is maintained during the solidification of the concrete and then released when fully solidified; thus, the elastic deformation of the steel rods is locked inside the concrete. ; project administration, B.W. This type of prestressing is adopted for mass scale production. Application of Time-Stress Superposition to Viscoelastic Behavior of Polyamide 6,6 Fiber and Its true Elastic Modulus. An improved laboratory technique for the measurement of tree initiation voltages in polymeric insulation is described, which allows a closer approach to the conditions in extruded cable insulation. The tendons can lie outside the member (for example in I-girders or walls) or inside the hollow space of a box girder. A reduction in temperature would lead to a loss of ductility. - Stricture at the yield point shall be equal to, or greater than, 25% in plain wires. Tensile testing was conducted using a universal testing machine to capture the mechanical properties of the PT strands, and the details of the test results are summarized in Table 3, . For example, circumferential prestressing of tanks, silos, pipes and similar structures. ; Madhukar, M.S. Most of the applications of prestressing are internal prestressing. E-mail: 2014 American Society of Civil Engineers, Journal of Performance of Constructed Facilities, Prestress Losses and Flexural Behavior of Reinforced Concrete Beams Strengthened with Posttensioned CFRP Sheets, Investigation of RC Beams Strengthened with Prestressed NSM CFRP Laminates, Prestressed Carbon Fiber Reinforced Polymer Sheets for Strengthening Concrete Beams at Room and Low Temperatures, Prestressed CFRP for Strengthening of Reinforced Concrete Structures: Recent Developments at Empa, Switzerland, Design and Site Application of Prestressed Carbon-Fiber-Reinforced Polymer Sheets for Strengthening Concrete Structures, https://doi.org/10.1061/(ASCE)CF.1943-5509.0000478, 19962023, American Society of Civil Engineers.