Top 10 biggest mistakes made in posttensioned concrete design. Posttensioned concrete slab tendons are unidirectional, snaking through the concrete to provide superior tension. The commentary is provided to mention the considerations of the committee in developing the criteria. Nov 25, 2008 post tensioned concrete is a term heard more and more in the construction industry today. Calculation and the theory by which the software works are attached with this softwares index, this thing is not seen on other softwares. Posttensioning is done onsite by installing posttensioning tendons within the concrete formwork in a manner similar to installing rebar. Post tension cables are steel wires inserted into plastic sheathing laid in place while pouring the concrete slab. Structural engineers decision on soil bearing area used. Post tension slab design software structural engineering. 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. Tension stress as multiple of fcu12 at top fibers 0. A post tensioned foundation is a concrete slab foundation that is reinforced with stranded steel cables that are tensioned after. For most people it makes perfect sense to simply use the rib width as the only bearing area when determining soil bearing pressure. Rapt is a two dimensional post tension beamslab design software.
Want to design concrete floors economically, with exceptional visibility into compliance, and efficiency while designing slabs, mats, and rafts. A properly designed post tension slab can design around expansive soils, high water tables, etc. In posttensioning it is necessary to use some types of device to attach or anchor the ends of the tendons to the concrete section. This spreadsheet program provides for the design and analysis of posttensioned concrete oneway beam and slab systems and twoway flat plate slab systems. Consider all major aspects of slab design including service, ductility, and strength limit states, codeprescribed requirements, longterm deflections, punching shear, and walking vibration.
Posttensioned multistorey timber buildings woodworks. Design posttensioned and conventional systems design elevated concrete slabs with or without posttensioning. 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. Concrete slab design software economically design posttensioned and reinforced concrete floors including slabs, mats, and rafts, with exceptional visibility into compliance, efficiency, and practicality. 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. Perpendicular to the tendons, the banded tendons run with the columns.
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. On the other hand, the banded and distributed tendons limit the potential forms of. Other design approaches for post tension slab ongrade foundations rely on simplified and approximate methods which largely lead to overly conservative designs. Post tension slab pa asnzs aunz code issues engtips. Fundamentals of posttensioned concrete design for buildings part one a suncam online continuing education course. Steel is strong under forces of tension, so combining the two elements results in the creation of very strong concrete components. A posttension slab is a slab of concrete that has been prestressed using a specific method to increase the strength of the concrete. Highstrength steel tendons are positioned in ducts or sleeves before the concrete is placed. I always assumed that post tension was more expensive but it actually looks like it may be cheap. Latinautor, latinautor peermusic, bmi broadcast music inc. Post tensioning can help create innovative concrete components that are thinner, longer, and stronger than ever before.
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. The posttensioning institute designed posttensioned foundations. 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. Several methods exist for prestressing concrete, with post tensioning being a very common one. 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. Can i install an underground safe room in a posttension slab. In continuous or indeterminate post tensioned structures the moments due to the prestressing. Slabworks is a program used for the analysis and design of stiffened slabongrade foundations on expansive clay and compressible soils. Jul 21, 2017 rapt is a two dimensional post tension beamslab design software. This cantilevered golf course green is actually a posttensioned concrete slab. Please whitelist this website or disable ad blocking software. Part three continues with the study of twoway, posttensioned slab systems, including. 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.
Post tension slab working principle, components and construction. Once the slab cures, qualified personnel apply tension and grout the cables. 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. The post tensioning institute designed post tensioned foundations. The program is divided into three separate screens, which correspond to the three major areas of concern in the design of a posttensioned member. 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. The designs were analysed using adapt builder software with different panel sizes. Slabworks implements all of the generally accepted foundation design methods pti, wri and brab for these types of foundations. Fundamentals of posttensioned concrete design for buildings. While concrete is strong in compression, it is weak in tension. 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.
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. A residential posttensioned concrete slab will typically be 8 inches thick and use 3000 psi concrete. Posttensioned pt slabs are typically flat slabs, band beam and slabs or ribbed slabs. Post tensioned beam analysis in structural bridge design. Members of the institute include major posttensioning material fabricators in the u. I am trying to model a posttensioned girder to australian standards as5100. A normal slab is basically a rcc reinforce cement concrete slab where as a post tentioned slab is the psc prestressed concret slab. 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. 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. 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.
Construction maintenance of post tensioned slab on ground. Top 10 biggest mistakes made in posttensioned concrete. International wood symposium 23 january 2014 vancouver bc posttensioned multistorey timber buildings professor andy buchanan university of canterbury, new zealand. Posttensioned walkways provide a structural upper fixed beam capping all walls and also provide for superior accessibility. Posttensioned, reinforced concrete slab design software ram. Prestressed concrete post tension slabs fundamentals udemy. Inserting tendons in the concrete is a very tedious and timeconsuming procedure, even if we do it just as 2d annotation. Prestressed concrete post tension slabs fundamentals. Before a post tension slab is poured, highstrength steel strands or cables, called tendons, are laid in a tight grid. Adapt corporation specializes in structural concrete design software for post tensioning, reinforced concrete, and prestressed beam, slab, foundation. Posttensioning is a method of reinforcing strengthening concrete or other materials with highstrength steel strands or bars, typically referred to as tendons.
We recommend using pt for temperature and shrinkage reinforcement. The example presented is taken from the book posttensioned 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. Several methods exist for prestressing concrete, with posttensioning being a very common one. What is the best software to design a post tension slab.
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. Precast posttensioned tanks can be constructed above ground with the base slab below frost, completely buried, or partially outofgrade. 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. Adaptrc software for the design, analysis, and investigation of reinforced nonprestressed concrete beams, slabs and floor systems. Adaptpt designs posttensioned slabs and beam frames using equivalent frame. These devices are usually referred to as end anchorages. Post tensioned foundation information for the homeowner. 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. Construction of post tensioned slabs on grade is very similar to using reinforcing steel, except for the tensioning step. 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.
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. Posttensioning with replaceable dissipaters may b th b t. Tanks can also be designed to withstand differential backfill. The alternative to pretensioning is posttensioning. The largest block, f north, contains transfer structures at ground and second floor level, but otherwise is a 220mm deep, 2way posttensioned flat slab. Usually a sign in the garage or stamp in the slab will indicate if your home has a post tension slab. Six problems with posttensioning force specifications.
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. And from what ive seen the cost of conventional vs post tension is about a wash. Posttensioning is a method of reinforcing concrete. 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. It appears that the posttensioning tool only works with british standard bs 5400. Posttensioning institute education pt applications. After decades of building and inspecting in the posttensioning pt. 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. 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. Pt slabs offer the thinnest slab type, as concrete is worked to its strengths, mostly being kept in compression. This latest and largest phase of the development features four posttensioned concrete frames up to ten storeys high. Post tension slab design software calvinandhobbes10 structural 26 aug 16 15. Design floors and foundations reliably and efficiently, saving time and money, and overcoming the most common concerns you face as a designer. 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.
I am using autodesk structural bridge design software and have the following query. Posttension basics how posttensioned slabs are built. Members of the institute include major post tensioning material fabricators in the u. Posttensioned concrete design spreadsheet program a pdh. 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. Its more user friendly compared to other pt design softwares. Structural calculations for posttensioned beam and oneway. 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. Once the concrete has gained strength to 2000 psi, typically within the 3 to 10 days recommended by pti, the tendons are stressed. What is the difference between normal slab and post.
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. 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. Structural engineers decision on soil bearing area used for. If you know what year your home was built andor which builder was used, we may be able to help you over the phone. In this video we will try to design a two span beam in pt designer, our latest post tensioned design software for more info. Posttensioning and prestressed design and software expertise for.
Reliance on 3d finite element software for design and drawings. Twoway posttensioned design amsysco post tensioning. 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. Adapt corporation specializes in structural concrete design software for posttensioning, reinforced concrete, and prestressed beam, slab, foundation. Pti has certification programs for manufacturing plants and. This hybridisation helps achieve the formation of a much thinner slab with a longer span devoid of any columnfree spaces. Structural calculations for posttensioned beam and oneway slab construction. Typically maximum fiber stress in tension controls design. The present study focuses on posttensioned flat slab systems with respect. Information about how posttensioned concrete is constructed.
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. Posttensioned concrete slabs augi the worlds largest. Contractors sometimes need to drill or cut into a post tensioned slab for repair or renovation work. Nov 19, 2016 the alternative to pretensioning is post tensioning. Unless otherwise noted, all referenced table, figure, and equation numbers are from these books. Post tension slab design software sethguthrie civilenvironmental 18 aug 16 19. Ignoring the effect of slab folds on tendon profile. A posttensioned foundation is a concrete slab foundation that is reinforced with stranded steel cables that are tensioned after.
Calculation and the theory by which the software works are attached with this softwares index, this thing is not seen. By using post tensioned tendons to compress the concrete, the formation of visible shrinkage cracks can be greatly. May 03, 20 very good video showing step by step post tension slab ahmed samir. Economically design post tensioned and reinforced concrete floors including slabs, mats, and rafts, with exceptional visibility into compliance, efficiency, and practicality. Fundamentals of posttensioned concrete design for buildings part one. Posttensioned concrete portland cement association. 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. Before a posttension slab is poured, highstrength steel strands or cables, called tendons, are laid in a tight grid. Posttensioned multistorey timber buildings professor andy buchanan university of canterbury, new zealand. 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. 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. Post tension slab working principle, components and. Posttensioning and prestressed design and software. Structural engineers design concrete slabs with posttension cables to obtain greater span lengths between supporting columns and to allow thinner slabs. 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. General overview of posttensioned concrete design instructor. Longer spans can be achieved due to prestress, which can also be used to counteract deflections. Calculation and the theory by which the software works are attached with this. When a concrete slab is stressed by the posttensioning method, it means the steel is being tensioned and the concrete is being compressed.
A psc is applied with a compressive stress on the cross section in advance before the application of loading on. Posttension basics how posttensioned slabs are built the. 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. Very good video showing step by step post tension slab ahmed samir. The following example illustrates the design methods presented in aci 31805 and ibc 2003. Very good video showing step by step post tension slab youtube.
It seems that you are using some ad blocking software which is preventing the page from fully loading. Today, pt is used extensively for slabs on grade where soils are likely to move expansive soilsespecially in the american southwest. 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. Very good video showing step by step post tension slab. Posttension cables are steel wires inserted into plastic sheathing laid in place while pouring the concrete slab. Cables are arranged as indicated by the engineer and chaired to run through the center of the slab. Adapt is a world leader in posttensioning and prestressed software and.
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