Highstrength steel tendons are positioned in ducts or sleeves before the concrete is placed. A post tensioned foundation is a concrete slab foundation that is reinforced with stranded steel cables that are tensioned after. On the other hand, the banded and distributed tendons limit the potential forms of. Once the slab cures, qualified personnel apply tension and grout the cables. Please whitelist this website or disable ad blocking software. The posttensioning institute designed posttensioned foundations. Prestressed concrete is basically concrete in which internal stresses of a suitable magnitude and distribution are introduced so that the stresses resulting from external loads are counteracted to a desired degree.
Slabworks implements all of the generally accepted foundation design methods pti, wri and brab for these types of foundations. Today post tension system is considered one of the most popular and required slab system due to its economical and rapid construction advantages for covering larger spans with lesser concrete slab thickness compared to the other traditional slabs. Top 10 biggest mistakes made in posttensioned concrete. Precast posttensioned tanks can be constructed above ground with the base slab below frost, completely buried, or partially outofgrade. Post tensioning can help create innovative concrete components that are thinner, longer, and stronger than ever before. The example presented is taken from the book posttensioned concrete. Jul 27, 2009 home articles structural engineers decision on soil bearing area used for post tension slabs ive been questioned several times about adequate rib width for post tension slabs.
It seems that you are using some ad blocking software which is preventing the page from fully loading. The following example illustrates the design methods presented in aci 31805 and ibc 2003. A residential posttensioned concrete slab will typically be 8 inches thick and use 3000 psi concrete. Twoway posttensioned design amsysco post tensioning.
Rapt is a two dimensional post tension beamslab design software. Ignoring the effect of slab folds on tendon profile. Posttensioning with replaceable dissipaters may b th b t. By using post tensioned tendons to compress the concrete, the formation of visible shrinkage cracks can be greatly. Ptislab can be used to design or analyze both posttensioned and conventionally reinforced slabsonground for single and multifamily residential and commercial foundations on expansive and. Posttension basics how posttensioned slabs are built. Today posttension system is considered one of the most popular and required slab system due to its economical and rapid construction advantages for covering larger spans with lesser concrete slab thickness compared to the other traditional slabs. Posttensioned, reinforced concrete slab design software ram. Longer spans can be achieved due to prestress, which can also be used to counteract deflections. Pti has certification programs for manufacturing plants and.
Slabworks is a program used for the analysis and design of stiffened slabongrade foundations on expansive clay and compressible soils. Adapt corporation specializes in structural concrete design software for posttensioning, reinforced concrete, and prestressed beam, slab, foundation, building and bridge structures using finite element or equivalent frame analysis. Post tension slab is a combination of conventional slab reinforcement and additional protruding highstrength steel tendons, which are consequently subjected to tension after the concrete has set. Other design approaches for post tension slab ongrade foundations rely on simplified and approximate methods which largely lead to overly conservative designs. The first edition of the posttensioning manual was published in 1972, and as of the time of this writing 2018, they are up to their 6th edition. Suncoast has a more depth and breadth of engineering talent than other posttension companies, with multiple professional engineers on staff, supported by a team of posttension technicians who work under licensed professional engineers using. Jim rogers, editor and publisher of post tension magazine, says that until housing construction ground to a halt last year, about half of all posttensioning work was slabsonground for homes. Fundamentals of posttensioned concrete design for buildings part one a suncam online continuing education course. Typically maximum fiber stress in tension controls design. The first edition of the post tensioning manual was published in 1972, and as of the time of this writing 2018, they are up to their 6th edition. Apr 05, 2020 a post tension slab is a slab of concrete that has been prestressed using a specific method to increase the strength of the concrete.
Prestressed concrete post tension slabs fundamentals. Structural calculations for posttensioned beam and oneway slab construction. And from what ive seen the cost of conventional vs post tension is about a wash. Post tension slab working principle, components and. Posttensioning is a method of reinforcing strengthening concrete or other materials with highstrength steel strands or bars, typically referred to as tendons. The systems used to posttension concrete and masonry consist of prestressing steel that is housed inside a duct or sheath, which allows the prestressing steel to be placed inside the typical job site formwork at the same time rebar and other.
Post tension cables are steel wires inserted into plastic sheathing laid in place while pouring the concrete slab. Nov 25, 2008 post tensioned concrete is a term heard more and more in the construction industry today. Tension stress as multiple of fcu12 at top fibers 0. International wood symposium 23 january 2014 vancouver bc posttensioned multistorey timber buildings professor andy buchanan university of canterbury, new zealand. Economically design post tensioned and reinforced concrete floors including slabs, mats, and rafts, with exceptional visibility into compliance, efficiency, and practicality. Posttensioned pt slabs are typically flat slabs, band beam and slabs or ribbed slabs. Before a posttension slab is poured, highstrength steel strands or cables, called tendons, are laid in a tight grid. What is the best software to design a post tension slab. For most people it makes perfect sense to simply use the rib width as the only bearing area when determining soil bearing pressure. Construction of post tensioned slabs on grade is very similar to using reinforcing steel, except for the tensioning step. Posttension basics how posttensioned slabs are built the.
Very good video showing step by step post tension slab youtube. This spreadsheet program provides for the design and analysis of posttensioned concrete oneway beam and slab systems and twoway flat plate slab systems. Here, in chapter 18, which is exclusively for prestressed concrete, all the aspects related to unbonded posttensioned system are nicely described which includes criteria for pt slab as well as pt beams. Jan 20, 2016 tendons with lateral curvature at low points have a tendency to blowout the bottom of the slab either immediately upon stressing or many years later. Nov 19, 2016 the alternative to pretensioning is post tensioning. Tanks can also be designed to withstand differential backfill. In slabs on ground, the friction between the slab and the ground acts to resist this shrinkage and results in what are commonly referred to as shrinkage cracks. A post tension slab is a concrete slab or foundation that contains high tension cables running through the concrete to increase strength and reduce cracking typically in areas with poor soil conditions. Design floors and foundations reliably and efficiently, saving time and money, and overcoming the most common concerns you face as a designer. Design and software expertise in posttensioning and prestressed concrete for over 30 years, adapt corporation has provided a full range of software products and engineering services for the modeling, analysis and design of prestressed pre or posttensioned concrete structures.
Today, pt is used extensively for slabs on grade where soils are likely to move expansive soilsespecially in the american southwest. Inserting tendons in the concrete is a very tedious and timeconsuming procedure, even if we do it just as 2d annotation. Posttensioned concrete slabs augi the worlds largest. Posttensioning is a method of reinforcing concrete.
Jim rogers, editor and publisher of post tension magazine, says that until housing construction ground to a halt last year, about half of all post tensioning work was slabsonground for homes. A normal slab is basically a rcc reinforce cement concrete slab where as a post tentioned slab is the psc prestressed concret slab. Post tension slab design software calvinandhobbes10 structural 26 aug 16 15. Structural engineers decision on soil bearing area used for. Posttensioning and prestressed design and software. Members of the institute include major post tensioning material fabricators in the u. Cables are arranged as indicated by the engineer and chaired to run through the center of the slab.
A posttensioned foundation is a concrete slab foundation that is reinforced with stranded steel cables that are tensioned after. A posttension slab is a slab of concrete that has been prestressed using a specific method to increase the strength of the concrete. Structural engineers decision on soil bearing area used for post tension slabs ive been questioned several times about adequate rib width for post tension slabs. This method of reinforcing concrete enables a designer to take advantage of the considerable benefits provided by prestressed concrete while retaining the flexibility afforded by the castinplace method of building concrete structures. Adapt corporation specializes in structural concrete design software for posttensioning, reinforced concrete, and prestressed beam, slab, foundation.
General overview of posttensioned concrete design instructor. After decades of building and inspecting in the posttensioning pt. In simple span beams the primary post tensioning pt moments induced by the prestressing force are directly proportional to the eccentricity of the tendons with respect to the neutral axis of the member i. Steel is strong under forces of tension, so combining the two elements results in the creation of very strong concrete components. If you know what year your home was built andor which builder was used, we may be able to help you over the phone. Perpendicular to the tendons, the banded tendons run with the columns. Six problems with posttensioning force specifications.
Structural calculations for posttensioned beam and oneway. The program is divided into three separate screens, which correspond to the three major areas of concern in the design of a posttensioned member. The contract work to be performed under this section consists of furnishing all required labor, materials, equipment, implements, parts and supplies necessary for, or appurtenant to, the site preparation and grading of tennis courts. Can i install an underground safe room in a posttension slab. The commentary is provided to mention the considerations of the committee in developing the criteria.
Concrete slab design software economically design posttensioned and reinforced concrete floors including slabs, mats, and rafts, with exceptional visibility into compliance, efficiency, and practicality. Adaptpt designs posttensioned slabs and beam frames using equivalent frame. Post tension slab working principle, components and construction. The contract work to be performed under this section consists of furnishing all required labor, materials, equipment, implements, parts and supplies necessary for, or appurtenant to, the. This latest and largest phase of the development features four posttensioned concrete frames up to ten storeys high. Posttensioning is done onsite by installing posttensioning tendons within the concrete formwork in a manner similar to installing rebar. The designs were analysed using adapt builder software with different panel sizes. Once the concrete has gained strength to 2000 psi, typically within the 3 to 10 days recommended by pti, the tendons are stressed.
Post tensioned foundation information for the homeowner. In this video we will try to design a two span beam in pt designer, our latest post tensioned design software for more info. Several methods exist for prestressing concrete, with posttensioning being a very common one. Suncoast has a more depth and breadth of engineering talent than other post tension companies, with multiple professional engineers on staff, supported by a team of post tension technicians who work under licensed professional engineers using stateofthe art engineering and cad software. In posttensioning it is necessary to use some types of device to attach or anchor the ends of the tendons to the concrete section. We recommend using pt for temperature and shrinkage reinforcement. In continuous or indeterminate post tensioned structures the moments due to the prestressing. The present study focuses on posttensioned flat slab systems with respect. The largest block, f north, contains transfer structures at ground and second floor level, but otherwise is a 220mm deep, 2way posttensioned flat slab. Latinautor, latinautor peermusic, bmi broadcast music inc. Part three continues with the study of twoway, posttensioned slab systems, including. Post tensioned concrete provides a light, structurally efficient, durable solution for the construction of commercial office buildings, residential apartments, highrise condominiums, and mixeduse facilities such as hotels and casinos. While concrete is strong in compression, it is weak in tension.
Structural engineers decision on soil bearing area used. I always assumed that post tension was more expensive but it actually looks like it may be cheap. I am trying to model a posttensioned girder to australian standards as5100. Prestressed concrete post tension slabs fundamentals udemy. Posttensioned concrete provides a light, structurally efficient, durable solution for the construction of commercial office buildings, residential apartments, highrise condominiums, and mixeduse facilities such as hotels and casinos. Contractors sometimes need to drill or cut into a post tensioned slab for repair or renovation work. This means the foundation is reinforced by cables laid in a grid arrangement and tensioned after the concrete cures sufficiently with the intent to create compression in the foundation concrete to resist cracking. Adapt is a world leader in posttensioning and prestressed software and. Calculation and the theory by which the software works are attached with this softwares index, this thing is not seen on other softwares. This cantilevered golf course green is actually a posttensioned concrete slab. Construction maintenance of post tensioned slab on ground. The alternative to pretensioning is posttensioning. The foundation in question was a posttension cable reinforced foundation as opposed to a foundation which is reinforced with steel rebar see the typical photograph in this article.
Consider all major aspects of slab design including service, ductility, and strength limit states, codeprescribed requirements, longterm deflections, punching shear, and walking vibration. Post tension slab design software structural engineering. Here, in chapter 18, which is exclusively for prestressed concrete, all the aspects related to unbonded post tensioned system are nicely described which includes criteria for pt slab as well as pt beams. May 03, 20 very good video showing step by step post tension slab ahmed samir. Very good video showing step by step post tension slab ahmed samir. These devices are usually referred to as end anchorages. Members of the institute include major posttensioning material fabricators in the u. Posttensioned multistorey timber buildings professor andy buchanan university of canterbury, new zealand. It appears that the posttensioning tool only works with british standard bs 5400.
Posttensioned concrete portland cement association. Before a post tension slab is poured, highstrength steel strands or cables, called tendons, are laid in a tight grid. This course provides the documentation to enable the use of a post tension design spreadsheet program for oneway concrete beam and slab and twoway concrete slab systems. In a posttensioned beam, the tendons are stressed and each end is anchored to the concrete section after the concrete has been cast and has. Posttensioned concrete design spreadsheet program a pdh. Usually a sign in the garage or stamp in the slab will indicate if your home has a post tension slab. Jul 21, 2017 rapt is a two dimensional post tension beamslab design software. Adapt corporation specializes in structural concrete design software for post tensioning, reinforced concrete, and prestressed beam, slab, foundation. Conventional uses more steel less concrete, post tension uses more concrete less steel at least on all of my designed slabs in east texas where expansive soil is. Pt slabs offer the thinnest slab type, as concrete is worked to its strengths, mostly being kept in compression. The post tensioning institute designed post tensioned foundations. Posttensioned walkways provide a structural upper fixed beam capping all walls and also provide for superior accessibility. Posttensioned multistorey timber buildings woodworks.
A psc is applied with a compressive stress on the cross section in advance before the application of loading on. Structural engineers design concrete slabs with posttension cables to obtain greater span lengths between supporting columns and to allow thinner slabs. I am using autodesk structural bridge design software and have the following query. Nov 03, 2017 a normal slab is basically a rcc reinforce cement concrete slab where as a post tentioned slab is the psc prestressed concret slab. Adaptrc software for the design, analysis, and investigation of reinforced nonprestressed concrete beams, slabs and floor systems. Design and software expertise in post tensioning and prestressed concrete for over 30 years, adapt corporation has provided a full range of software products and engineering services for the modeling, analysis and design of prestressed pre or post tensioned concrete structures. Unless otherwise noted, all referenced table, figure, and equation numbers are from these books. Hi, i am relatively new in designing post tension member and as a start i am trying to study how rapt do the design of post tension slab. Fundamentals of posttensioned concrete design for buildings. Top 10 biggest mistakes made in posttensioned concrete design. Posttensioning institute education pt applications.
Post tension slab design software sethguthrie civilenvironmental 18 aug 16 19. Calculation and the theory by which the software works are attached with this. Post tension slab pa asnzs aunz code issues engtips. Its more user friendly compared to other pt design softwares. Very good video showing step by step post tension slab. Reliance on 3d finite element software for design and drawings. Fundamentals of posttensioned concrete design for buildings part one. Posttension cables are steel wires inserted into plastic sheathing laid in place while pouring the concrete slab. Posttensioned concrete slab tendons are unidirectional, snaking through the concrete to provide superior tension. Information about how posttensioned concrete is constructed. Posttensioning and prestressed design and software expertise for. Post tensioned beam analysis in structural bridge design. In a post tensioned beam, the tendons are stressed and each end is anchored to the concrete section after the concrete has been cast and has. Posttensioning and prestressed design and software expertise.
Once the concrete has gained strength, tension is then applied, pulling the tendons and anchoring them against the outer edges of the concrete, before service loads are. What is the difference between normal slab and post. Design posttensioned and conventional systems design elevated concrete slabs with or without posttensioning. A properly designed post tension slab can design around expansive soils, high water tables, etc. Several methods exist for prestressing concrete, with post tensioning being a very common one. This hybridisation helps achieve the formation of a much thinner slab with a longer span devoid of any columnfree spaces.
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