Anyway, application for the post tensioning slabs system include. For this, the concrete slab is tensioned with a process called prestressing and the slab of concrete which comes out after this process is known. However, the beams divide the plenum space into channels, reducing the overall utility. Posttension basics how posttensioned slabs are built. Guidelines for the design of post tensioned floors by bijan o. The example presented here is for twoway posttensioned design. To create a slab using this method, plastic sleevecovered steel cables are laid in a grid running in both directions. Posttensioned pt slabs are typically flat slabs, band beam and slabs or ribbed slabs. 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 present study focuses on posttensioned flat slab systems with respect to strength. Nov 25, 2008 post tensioned concrete is a term heard more and more in the construction industry today. Post tensioning for twoway flat plate construction figure 2. Cables are arranged as indicated by the engineer and chaired to run through the center of the slab. In california, post tensioned floor slabs are the primary choice in concrete floor construction. It is based on data and knowledge considered to be true and accurate and is offered for consideration, investigation and verification by the user, but we do not warrant the results to be obtained. The design of posttensioned flat slab can be done by. Post tensioning in buildings is not limited to floor slabs.
Design floors and foundations reliably and efficiently, saving time and money, and overcoming the most common concerns you face as a designer. Post tension slab advantages and disadvantages of post. Pdf analysis and design of rcc and posttensioned flat slabs. Ccl posttensioning results in thinner concrete slabs. Deflection check of post tensioned floor systems this narrative outlines the procedure for deflection check in design of post tensioned floor systems. Stronger, more efficient floor slab design creates longer spans and reduces the need for columns within the structure.
The purpose of this publication is to widen the understanding of post tensioned floor construction and show the considerable benefits which include minimum storey heights, rapid construction, economy, maximum design flexibility, minimum number of columns, optimum clear spans, jointfree, crackfree. For professionals engaged in posttensioning design. It provides an architect the freedom to work freely with his designs. The execution of the design will be explained with reference. By doing the comparative analysis and design of post tensioned flat slab with a conventional slab, we can show how beneficial will be the process of making pt flat slab than other slabs. Download tr43 posttensioned concrete floors design. The design of posttensioned flat slab can be done by using load balancing and equivalent frame. Posttensioned, reinforced concrete slab design software ram. The decision to use bonded tendons in twoway posttensioned slabs must be made very carefully, particularly when the slab design is governed by aci 31811. Unbonded tendons offer unique structural advantages not found in. 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. April 8, 2017 admin design comments off on download tr43 post tensioned concrete floors design handbook 2nd by concrete society working party pdf by concrete society working party seeing that post tensioned concrete flooring was once first released in 1994, using put up tensioned concrete flooring in constructions has endured to develop always.
Concrete slab design software economically design post tensioned and reinforced concrete floors including slabs, mats, and rafts, with exceptional visibility into compliance, efficiency, and practicality. Post tension slab working principle, components and. Once the concrete has gained strength to 2000 psi, typically within the 3 to 10 days recommended by pti, the tendons are stressed. Jurgens his article presents a set of guidelines intended to t assist designers in routine post tensioning design, beginning with a discussion of the initial decisions that must be made to design post tensioned floor.
Posttensioning institute pti design manual6 gives recommended spantothickness ratios for slabs and. Developers, architects, engineers, contractors, educators and. Design objective to mitigate the probability of undesirable effects in. Allowable deflection limits refer to table 1 of the appendix. This course is intended to be an introductory course for structural engineers new to post tensioned. This spreadsheet program provides for the design and analysis of post tensioned concrete oneway beam and slab systems and twoway flat plate slab systems. Jurgens his article presents a set of guidelines intended to t assist designers in routine post tensioning design, beginning with a discussion of the initial decisions that must be made to design post tensioned floor members. Architectural benefits post tensioned slab has an advantage over others as it makes a very efficient base for floor design with thin slabs and columnless spaces in larger spans. This video tutorial is about pts post tension slab design which is trained by master of structural engineering mr. These specifications are included chapter 18, division iii, section 1816 titled. Part three continues with the study of twoway, post tensioned slab systems, including.
Post tensioned slab has an advantage over others as it makes a very efficient base for floor design with thin slabs and columnless spaces in larger spans. The alternative design proposed was a 250mm thick post tensioned base slab which was tapered to a 700mm thickening at the base of the walls to deal with the wall moments and base shear. Structural calculations for posttensioned flat slab. Use the download button below or simple online reader. Posttensioned concrete design spreadsheet program a pdh. These results were compared with other information, i. Tendon profile of a continuous post tensioned beam. Guidelines for the design of posttensioned concrete floors. Pt designer design of posttensioned concrete floors.
A detailed explanation will be given of the checksto. Engineers had to learn how to design pt floor systems with levels of cracking normally accepted in nonprestressed floor systems. 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. Clean out of the footings after a rain is much faster and neater than rebar type foundations. These slabs have been proved to be the most economical when compared to the rcc slabs. Five underlying features of post tensioned construction allow greater flexibility in reinforcement layout. Aalami a must have reference book for engineers, students, contractors, building officials, and researchers. The following example illustrates the design methods presented in aci 31805 and ibc 2003. The concrete society in england publishes a design handbook6 for post tensioned concrete floors that includes recommendations for twoway slabs with both bonded and unbonded tendons. Design of post tensioned buildings for wind and seismic forces, including diaphragm design. Post tensioned slabs application pt reinforcement is used more in the residential market than in any other sector of construction. This was achieved by using a post tensioned concrete slab with post tensioned upturn concrete beams.
Post tension design of slab there is document post tension design of slab available here for reading and downloading. Fundamentals of posttensioned concrete design for buildings. Limitations on slab dimensions and required material quantities are presented and discussed. Roof floor roof floor oneway solid slabs 50 45 45 40 twoway solid slabs 4548 4045 na na. Post tensioned slabs can be designed to be 100% crack free, which means the slabs. Brendon burley structural option post tensioned twoway slab post tensioned twoway slab introduction the filigree beam system creates a thin lightweight floor system that leaves plenty of open plenum space for mechanical and electrical equipment.
The posttensioned system was designed to span the same lengths as the composite system while maintaining a relatively thin. 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 file extension pdf and ranks to the documents category. The design of post tensioned flat slab can be done by using load balancing and equivalent frame. Review of the essential technical knowhow for efficient design. Pt designer is a computer program for the design and analysis of linear post tensioned concrete floor systems. As these slabs are very easy to construct, post tensioned slabs are preferred for industrial, commercial and residential floor slab construction. Example input for design of post tensioned slabs ongrade the 2000 international building code ibc includes special provisions for the design of post tensioned floor slabs on expansive soils.
For slabs with both bonded and unbonded tendons, this handbook recommends exactly the same minimum amount of bonded reinforcement over. An overview is presented on the application and design of such floor systems, and the commonly selected castinplace floor system configurations are described. It is based on the recommendations of aci318 as expounded in adapt technical note tn292. Longer spans can be achieved due to prestress, which can also be used to counteract deflections. The advantages are many, when compared to non post tensioned systems, and include thinner slabs, lighter structures, lower floor to floor heights, less mild reinforcing steel, and less short and long term deflections. Tn342 design example 2way mondada 093090 adapt corporation. Post tension slab although concrete is a strong material for construction, it is not resistant to breakdown especially where longer concrete slabs are required like in a bridge or a length of a beam.
Commercial opportunities ccl post tensioning results in thinner concrete slabs. Fundamentals of post tensioned design for buildings. Low to high rise residential and commercial buildings industrial floor slabs on the ground. Pt slabs offer the thinnest slab type, as concrete is worked to its strengths, mostly being kept in compression. Twoway slab systems twoway post tensioned slab systems have been widely used in building construction for many decades. To maximize views for the premium units in the upper floors, more glazing and less concrete wall had to be incorporated into the design of the north back face of the tower at. It was actually the widespread use of the post tensioned slab onground which induced this interest in design procedure and in many studies of reported slab failures. This stronger, thinner slab also saves money on concrete. Fundamentals of posttensioned concrete design for buildings part one a suncam online continuing education course. Pt designer is a computer program for the design and analysis of linear posttensioned concrete floor systems. Post tensioned concrete design table 11 list of symbols used in the aci 31808 code m bal design moment resistance of a section with tendons and the necessary mild reinforcement to reach the balanced condition, nmm m u factored moment at section, lbin n c tension force in concrete due to unfactored dead load plus live load, lb p.
Framing dead load selfweight superrimposed dead load 25 psf partitions, me, misc. Unless otherwise noted, all referenced table, figure, and equation numbers are from these books. Post tensioned concrete floors form a large proportion of all prestressed concrete construction. How to create a concrete slab using the posttensioning method. Jan 24, 2015 post tension slab although concrete is a strong material for construction, it is not resistant to breakdown especially where longer concrete slabs are required like in a bridge or a length of a beam. To maximize views for the premium units in the upper floors, more glazing and less concrete wall had to be incorporated into the design of the north back face of the tower at levels 30 through 38. Net, which many engineers have come to trust over the years for its accuracy and flexibility. The program is developed around the robust computational core of two popular programs ptdata. Us post tensioning industry owes its existence to lift slab construction first lift slab buildings in the us were built in the mid 1950s using nonprestressed slabs problems with deflections and slab weight in long 2way spans to solve deflection and weight problems, lift slab companies changed to post tensioned slabs. While using this method more precautions has to be made for shear and deflection criteria for the slabs. A detailed explanation will be given of the checksto be carried out, the aspects to be considered in the design and the construction procedures and sequences of a post tensioned slab.
Twoway posttensioned design amsysco post tensioning. Design method may not be used for twoway, posttensioned slab systems. Actual losses, whether greater or smaller than computed values, have little effect on the design strength of the member but do affect service load conditions i. This article provides information on how to scheme a pt slab and how the use of post tensioning affects the rest of the structure. Fewer joints large concrete areas, such as tennis courts, parking lots. Nowadays, design of modern an architectural building structures requires the use of slender and free from numerous supports slabs. In post tensioned floor slab construction, the placement of post tensioning tendons and associated nonprestressed reinforcement does not strictly follow the practice of nonprestressed slabs. Post tensioned floors design for temperature florian aalami april 28, 2015. A more detailed guide to the design of pt floors can be found in the concrete societys technical report 43 tr43. This method is a better way to construct a slab foundation to be more resistant to cracking and deflection. Our aim is to enable all those involved in the design, use and performance of concrete and masonry to realise the potential of. A residential post tensioned concrete slab will typically be 8 inches thick and use 3000 psi concrete.
The following table of prestress losses is recommended for the design of post tensioned members, and does not include friction or wedge set losses. Reducing the slab thickness has the benefit of reducing the floor dead loads, which results in an economical design of the concrete columns and footings. Agenda design objective response of floor slabs to temperature effects design procedure for control of temperature cracks example. General overview of posttensioned concrete design instructor. Design of slabs onground reported by aci committee 360 aci 360r06 this document presents information on the design of slabs onground, primarily industrial floors.
Post tensioned pt concrete floors are now widely used in the uk, particularly for highrise buildings. The concrete centre provides material, design and construction guidance. Post tensioned slabs use highstrength tensioned steel strands to compress the slabs, keeping the majority of the concrete in compression. Post tensioning concrete increases the many benefits associated with a concrete framed building. The recommendations derived from these and other studies vary from extremely light to extremely heavy. Construction of post tensioned slabs on grade is very similar to using reinforcing steel, except for the tensioning step. The preliminary design proposal was to build the entire slab in a single pour, but due to. The use of post tensioned flat slab is increasing widely, due to its advantages over traditional concrete.
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