Strand systems st r and systems are based on use of 7wire strand with 270,000psi guaranteed ultimate tensile strength 270k in diameters of 3. Bonded and unbonded post tensioning technologies post tensioning systems in building construction supervised by. Pre tensioning can be further classified into two categories such as linear pre tensioning and circular pre tensioning. Recommendations for acceptance and application of posttensioning systems pdf fip reports 1981. The first ever structure built with a prototype of the dywidag bar post tensioning system was the alsleben arch bridge in germany in 1927. Anchor systems for unbonded post tensioning singlestrands ah sir cho, and thomas h. It has a straight central wire, called a core or king wire, around which six wires are spun in one layer. The main objective of the bulletin is to point out the benefits of using post tensioning for. Post tensioning systems have been stringently tested under the requirements of the most important international legislation such as european technical approval guideline etag0 and aashto lrfd bridge construction specifications. Posttensioning is simply a way to reinforce in a more active way. Recommendations for acceptance and application of post tensioning systems. Macalloy 1030 the macalloy 1030 post tensioning system consists of high tensile alloy steel bars in diameters from 25mm to 75mm, provided with cold rolled. Kang received september 30, 2017, accepted january 6, 2018 abstract. Dywidag bonded posttensioning systems using strands.
High strength steel wires of 5mm or 7mm diameter, numbering 8 or 12 or 16 or 24 are grouped into a cable with a helical spring inside. Pre tensioning is one method of applying prestress. Most importantly, there is the quality and service of vsl specialised highperformance site teams and unequalled backup. Pretensioned concrete is a variant of prestressed concrete where the tendons are tensioned prior to the concrete being cast 25 the concrete bonds to the tendons as it cures, following which the endanchoring of the tendons is released, and the tendon tension forces are transferred to the concrete as compression by static friction. Jul 28, 2011 detensioning unbonded post tension tendons posted on july 28, 2011 by neel khosa on rare occasions, the ironworkerinstaller will need to detension an alreadystressed post tensioning tendon. Detensioning unbonded posttension tendons amsysco post. The systems used to post tension concrete and masonry consist of prestressing steel that is housed inside a duct or sheath, which allows.
Posttensioning tendons, which are prestressing steel cables inside plastic ducts or sleeves, are. Systems are also foreseen for the slab post tensioning. Posttensioning methods for reinforcing concrete the. Post tensioning tendons, which are prestressing steel cables inside plastic ducts or sleeves, are.
The following table summarises the main advantages of slab post tensioning. For turnkey packages, tendon system offers a cost effective labor force to provide complete installation services for all posttensioning, shearails tm and rebar materials. Page 3 of slab post tensioning technical document first direct advantage related further advantages. Post tensioning systems european technical assessment dsi monostrand prestressing system l1l7 with cast iron anchors unbonded post tensioning kits for prestressing of structures with 1 to 7 monostrands 09. Post tensioning terminology ptt november 20 page 2 of 33 bearing plate, basic flat steel plate that transfers the tendon force directly into the concrete, meeting the analytical design requirements of pti acceptance standards for post tensioning systems, section 3.
As a specialized contractor with decades of experience in the specific field, tensacciai is able to provide not only the products and the. Contact sdo for approved post tensioning system vendor drawings for use with prejanuary 2016 specifications. Post tensioning is a method of reinforcement employing highstrength steel strands or bars, which enable the existence of longer clear spans, thinner slabs and in many cases of structural systems that would otherwise be impossible due to either site constraints or architectural requirements. Post tensioning is simply a way to reinforce in a more active way. This manual contains updated information on the current practices in the use, design, and construction of post tensioning.
It is giving me immense pleasure to introduce ourselves as vh pt systems, head office at surat in the western region of india, is uniquely positioned to address the commercialresidentialbridge post tensioning systems for better utilization of space and architectural flexibility. European technical assessment posttensioning systems. General overview of posttensioned concrete design instructor. Technical field service representatives provide our clients with onsite assistance for tendon systems installation, stressing and construction sequencing. Pre tensioning is accomplished by stressing wires or strands, called tendons, to predetermined. Post tensioned concrete is a variant of prestressed concrete where the tendons are tensioned after the surrounding concrete structure has been cast 25 the tendons are not placed in direct contact with the concrete, but are encapsulated within a protective sleeve or duct which is either cast into the concrete structure or placed adjacent to it. Aug 20, 2017 in this video you will be knowing about all the post tensioning systems adopted in the world by different countries. The prestressed concrete design of a structure is influenced by either of the two processes, pre tensioning, and posttensioning.
There is less material handling on site, reducing site labour force which reduces site activity congestion. Pdf unbonded posttensioning concepts and applications in. Vsl systems have a wellearned reputation for their quality, reliability, and durability and have been used throughout the world since 1956 to build, repair, and strengthen buildings, tanks, transportation and special structures. Recommendations for acceptance and application of post.
The kit supplied by macalloy co 25mm50mm diameter complyur. As the pressure in the press is released, the strands are automatically locked in the conical holes of the anchor head. In addition to the traditional post tensioning system using bars, that is mainly geared towards geotechnical applications, building rehabilitation and strengthening, dsi offers a complete product line in strand post tensioning bonded, unbonded and external as well as staycables being able to fully serve the post tensioning construction. These methods are generally adopted in the making of psc girders, sleepers etc. Pretensioning and posttensioning method civil snapshot. Working for clients across the world, ccl has the experience and a proven ability to create solutions that help reduce timescales and deliver exceptional results. Macalloy post tensioning systems is mprises plain bar 25mm40mm diameter and rit lg with pren 108, threaded coupler, anchor p upplicd by macalloy arc specified to comply w. Recommendations for acceptance and application of post tensioning systems pdf fip reports 1981. Ccl operates a fullyintegrated supply chain through.
Freyssinet system was introduced by the french engineer freyssinet and it was the first method to be introduced. Difference between pretensioning and posttensioning. Post tensioning institute pti design manual6 gives recommended. Tendons either pass through a single mould or a line of moulds for multiple members arranged end. Post tensioning is a method of reinforcing strengthening concrete or other materials with highstrength steel strands or bars, typically referred to as tendons. This manual includes stateoftheart information relative to materials, posttensioning systems, construction practices and grouting of posttensioning tendons for. This manual includes stateoftheart information relative to materials, post tensioning systems, construction practices and grouting of posttensioning tendons for. It allows slabs and other structural members to be thinner. Pre tensioning is a method where prestressing steels are prestressed, prior to concreting, against two rigid abutments. After a brief introduction to current post tensioning systems and construction practice, the course continues with the economics of both grouted and unbonded options, and covers the practical design concepts and design procedures for beams, oneway and column supported twoway flat slab construction. What is the difference between pretension and post tension.
Posttensioning is the system of choice for parking structures since it allows a high degree of flexibility in the column lay out, span lengths and ramp configurations. Pre tensioning and post tensioning both method are used under prestressing process which have few edge over the orthodox nonstressed structures like more span to depth ration, higher moment and shear capacity. Post tensioning tendon installation and grouting manual fhwa. Specification goals set a minimum standard for all grouted post tensioning define the design and testing requirements before a post tensioning systems can be used give the ownerengineer a choice of performance levels in a post tensioning system. Systems are also foreseen for the slab posttensioning. Unbonded posttensioning system technology in building construction 123 fabrication of monostrand sheathing was supplied until the early to mid1990s. Posttensioning, which is a form of prestressing, has several advantages over standard reinforcing steel rebars. February 2000 overview post tensioning is a method of reinforcing strengthening concrete or other materials with highstrength steel strands or bars, typically referred to as tendons. Dywidag posttensioning systems multistrand systems. The 6th edition has been extensively expanded with 12 new chapters that give design guidance on modern applications of post tensioning.
Posttensioning systems and procedures springerlink. Developers, architects, engineers, contractors, educators and. From that time on dywidag has continuously improved its systems to keep up with the growing demand of modern construction technology. In simple span beams the primary post tensioning pt moments induced by the prestressing force are. External post tensioning is defined as a system in which the prestressing tendons or bars are located outside the concrete section. Post tensioning applications include office and apartment buildings, parking structures, slabsonground, bridges, sports. Product overview strand post tensioning systems monostrand pt systems bar post tensionig systems structural repair solutions dyna force elastomagne. Post tensioning in buildings foreword working party wp1. Dywidag systems international dsi offers a complete product line in strand and bar post tensioning bonded. Draped harped profiles temporarily held in place before concrete is hardened debonding not all strands are active at end of span strategies for post tensioned systems. Precast posttensioned segmental construction is defined as a method of construction for bridges, buildings, tanks, silos, cooling towers, tunnels and other structures in which primary load carrying members are composed of precast concrete segments post tensioned together. The pretensioning and posttensioning both methods are. Structures design office posttensioning jan 2016 later. It presents an integrated and seamless process for generating structural calculations, posttensioning and.
In corrosive environments, stuffed and heatsealed tendons have the inherent shortcoming of either trapping or allowing access of corrosive substances in the oversized sheathing. Structural technologies is the exclusive manufacturer of vsl post tensioning products and construction systems in the united states. Dywidag bar post tensioning systems a successful tradition. History the first posttensioning systems consisted of. A 2 2area 2 a c 2 2 post tensioned concrete design table 11 list of symbols used in the aci 31808 code cp area enclosed by the outside perimeter of the section, in a g gross area of concrete, in a 2 l total area of longitudinal reinforcement to resist torsion, in a o area enclosed by the shear flow path, sqin a oh area enclosed by the centerline of the outermost closed. Pdf a new steel anchorage system for posttensioning. Vsl post tensioning systems use a unique system for anchoring the prestressing force. Krauser march 15, 2007 unbonded post tensioning is an efficient structural system that has successfully been used worldwide in construction. Jul 10, 2015 the use of post tensioning system in building offers numerous advantages such as economic savings, minimised floortofloor heights, increased columnfree space, minimised foundations, in seismic areas, reduced weight and lateral load resisting systems, simplified slab design and construction etc. Posttensioning system for slabs monostrand system pts system dtsptgen0009 dts0023. Post tensioning, seismic design, post tensioning manual. A more detailed explanation of the macalloy post tensioning system is available in the macalloy 1030 european technical approval, document eta070046.
Pretensioning and posttensioning in prestressed concrete. Dywidag posttensioning systems multistrand systems repair. Unbonded tendons systems consist of prestressing steel wire, strand. Our manufacturing facilities in the united states are certified by ptis plant certification program to ensure the highest quality fabrication of materials. Difference between pre tensioning and posttensioning. As a leading post tensioning specialist, utracon had constructed more than 10 million square meter of post tensioned floor since 1998 worldwide. Post tensioned systems have large active forces and only knowledgeable and experienced personnel should be involved in the execution of repairs, modifications, and strengthening. Dsi offers the latest corrosion protection technology using proven methods and.
Unbonded post tensioning system technology in building. This system is not approved for applications where segmental duct couplers are required. Prestress concrete unbonded posttensioning youtube. In that year, a tradition began that we have successfully continued on a global scale until today. In present days the pretensioning and post tensioning systems are very popularly using in the major constructions of a structure. Post tensioning of foundations, transfer beams and plates, post tensioned masonry and the combination of precast elements with castinplace concrete by means of post tensioning offer other interesting opportunities.
Post tensioning is a technique for reinforcing concrete. Using the post tensioning method of prestressing enables a builder to get all the. Bonded slab posttensioning structural technologies. Through the process of testing and approval bodies evaluation, post tensioning systems have been granted european.
In some regions, the suppliers of post tensioning materials are subcontractors and contract for the materials installed. As a result of our ability to vary the number of strands in our tendons, our systems offer a high degree of flexibility and can always be adapted to suit individual clients needs. The strands always remain in contact with the anchoring wedges during the stressing operation. Members of the institute include major post tensioning material fabricators in the u. Originally post tensioned, twoway slab framing systems. A pioneer in prestressing, freyssinet now offers a cuttingedge posttensioning system combining performance and durability.
Posttensioning in buildings foreword working party wp1. Temporarily held in place before concrete is hardened. Advantages and benefits of unbonded post tensioning by larry b. General principales local zone design general zone design. The vsl multistrand system comprises from three to. There are a wide range of advantages and benefits for large as well as small projects. Post temsioning system have the following significant features and advantages. The prestressing force is transferred to the member section. The components of the dywidag bar system are manufactured in the united states exclusively by dywidag systems international. An animation movie which illustrates almost all the activities related to mono strand unbonded post tensioning system. The 6th edition has been extensively rewritten and expanded from the 5th edition, published in 1990. Tendon systems is a nationally recognized leader in the field of advanced concrete construction methods, made possible by the development and application of post tensioning techniques that form our core business.
Used worldwide since 1965, the system provides a simple, rugged method of efficiently applying prestress force to a wide variety of structural applications including post tensioned concrete as well as rock and soil anchor systems. Post tensioned general principales local zone design general zone design examples from pratice published by vsl international ltd. The posttensioning system consists of a flat duct filled in with 4 prestressing strands, and live or deadend anchorages. It reduces or eliminates shrinkage crackingtherefore no joints, or fewer joints, are needed. Macalloy post tensioning system detailing there are many permutations possible, to achieve satisfactory construction details and advice is readily available from the technical department. Versatile, lightweight and compact, but immensely strong, ccls range of bespoke and standard systems gives engineers and contractors the flexibility they need to deliver cuttingedge contemporary structures on time and within budget. The outer wire is tightly spun around the central wire with a lay length between 14 and 18 times. Pre tensioning and posttensioning both methods are used under prestressing process which has few edges over the orthodox nonstressed structures like greater span to depth ratio, higher moment and shear capacity. Following, presently used tendon systems for unbonded posttension will be shown.
Post tensioning is done at a project site and requires little to no modifications of the same forming system that would be used to construct nonprestressed concrete. The strand used in ccl posttensioning systems is manufactured from seven cold drawn wires and is termed a 7 wire prestressing strand. Freyssinets technical services design anchors, jacks and installation equipment, and also operate a test centre and a laboratory for the formulation of grouts. The specialist firms in post tensioning normally can supply field technicians qualified to supervise and instruct workers in the correct methods and procedures for installing, stressing, and grouting their products.
Post tensioning in buildings is not limited to floor slabs. Improved inspection techniques for steel prestressingpost. These systems provide maximum effective posttensioning forces in a single tendon that range from about 14,000 pounds in a sin. Tmg is a singapore based company specialised in post tensioning system. Ups bonded post tensioning system is a very efficient flat anchorage system designed by utracon in house engineers and tested in independent laboratories to comply with the latest international codes. The implementation of external post tensioning systems is a very. Thanks to the ducts flat shape, the system maximally uses the limited static height of slab structures, thus increases the effect of the introduced prestressing.