The file extension pdf and ranks to the documents category. A more detailed guide to the design of pt floors can be found in the concrete societys technical report 43 tr43. Anchorages provide for the safe introduction of post tensioning forces into the concrete. Commercial opportunities ccl post tensioning results in thinner concrete slabs. Precast post tensioned 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 recommendations derived from these and other studies vary from extremely light to extremely heavy. From the design criteria, the posttensioned slab is designed for a uniformly distributed superimposed dead load of 3.
In the general case, the design moments used for the. Structural calculations for posttensioned flat slab. Figure s42 three dimensional view of the post tensioned slab and its support arrangement s5 loading assumptions and values from the design criteria, the post tensioned slab is designed for a uniformly distributed superimposed dead load of 3. 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. Post tensioned slabs are intrinsically waterproof and. Typical applications of post tensioned slabs as already mentioned, this report is concerned exclusively with post tensioned slab structures. Usually a sign in the garage or stamp in the slab will indicate if your home has a post tension slab. Twoway pt slab design tutorial with adaptfloor pro. Structural calculations for posttensioned beam and oneway. Cables are arranged as indicated by the engineer and chaired to run through the center of the slab. Tensioning building structures miroslav vejvoda, p. Consider all major aspects of slab design, including service, ductility, and strength limit states, punching shear requirements, longterm deflections, and walking vibration. In certain applications, slabs in the order of 10,000m 2 have been constructed without movement joints.
Post tensioned slabs advantages the primary reason for the initial economy of post tensioned industrial floors is the reduced thickness of the concrete slab, permitted because of the compressive stress induced in the concrete by the post tensioning tendons. The choice of concrete mix and curing methods along with quality workmanship also play a key role. 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 part one a suncam online continuing education course. General overview of posttensioned concrete design pdh online.
Our future vision pti envisions a future in which post tensioning is the first choice for reinforcing all structures. In the design section they have started from the very basics so that even a new comer will be able to understand without any difficulty. Tensioning building structures march 12, 2020 2020 educode las vegas. Pdf new methods in efficient posttensioned slab design using. Two examples, one of a flat slab and one of a foundation raft, illustrate the design of these structures and the application of the present recommendations. These foundations will typically contain less reinforcement prestressed and.
Pretensioning and posttensioning in prestressed concrete design. 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. Aalami a must have reference book for engineers, students, contractors, building officials, and researchers. In pt design, it is preferable to draw moment diagrams to the tensile face of the concrete section. Five underlying features of post tensioned construction allow greater flexibility in reinforcement layout.
Stronger, more efficient floor slab design creates longer spans and. 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. To get the excel sheet join as loving fansub member to this channel. Post tension slab working principle, components and. Post tensioned concrete foundations designed by thi s standard generally meet the requirements for plain concrete specified in chapter of aci 31814 14 1. A combination of these values will determine the slab stresses at the time of stressing and at service loads. Difference between pre tensioning and post tensioning. Design floors and foundations reliably and efficiently, saving time and money, and overcoming the most common concerns you face as a. Lin in the early 1960s and extended to nonprismatic members by the author, has led to increased application of post tensioning in building construction. Post tensioning for twoway flat plate construction figure 2.
Post tensioning utilizes high quality high strength steel such that 1 kg of post tensioning strand may replace 3 or 4 kg of ordinary nonprestressed reinforcement. This article provides information on how to scheme a pt slab and how the use of post tensioning affects the rest of the structure. Notice the assumptions required for the post tensioned design fig. M ed is that part of the unbalanced slab bending moments that is transferred into the column at the support. Tn342 design example 2way mondada 093090 adapt corporation. 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.
The example presented here is for twoway posttensioned design. Sarkisian and others published new methods in efficient posttensioned slab design using topology optimization. Ribbed slabs there are two basic types of post tensioned residential slabs. Twoway posttensioned design amsysco post tensioning. Design method may not be used for twoway, posttensioned slab systems. Fundamentals of post tensioned design for buildings. The company helps its partners design and build more imaginative, efficient and durable structures. These methods are generally adopted in the making of psc girders, sleepers etc.
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. Jun 04, 2019 basic load balancing, introduced by t. Experienced specialty contractors and engineers have the knowhow to develop and execute repairs of unbonded post tensioning tendons, make modifications to existing unbonded post tensioned structures. The execution of the design will be explained with reference.
Pre tensioning is accomplished by stressing wires or. Sep 09, 2016 course study on post tension slab design. When zd is determined, the prestressing force required to balance an. Pretensioning and posttensioning in prestressed concrete. Ccl is an expert in post tensioned and pre tensioned concrete technology and is the number one supplier of prestressed concrete solutions in buildings. In any span, the max cable sag, zd depends on the concrete cover requirements and the tendon dimensions. Construction of posttensioned slabs on grade is very similar to using reinforcing steel, except for the tensioning step. Pt slabs offer the thinnest slab type, as concrete is worked to its strengths, mostly being kept in compression. Framing dead load selfweight superrimposed dead load 25 psf partitions, me, misc. The term prestressing is used to describe the process of introducing internal forces or stress into a concrete or masonry element during the construction process in order to. Design method may not be used for twoway, post tensioned slab systems. When moment is drawn on the tension side, the diagram matches the general drape of the tendons. Pre tensioning can be further classified into two categories such as linear pre tensioning and circular pre tensioning. Ccl posttensioned slabs can bring unique freedom over conventional building methods.
Use the download button below or simple online reader. Construction maintenance of post tensioned slab on ground. Approved by the former fip commission 3 practical design and the fip council, it is hoped that these recommendations will facilitate the correct design of post tensioned slabs and. General overview of post tensioned concrete design. What is posttensioning introduction post tensioning is a method of producing prestressed concrete, masonry and other structural elements. Developers, architects, engineers, contractors, educators and.
What is post tensioning introduction post tensioning is a method of producing prestressed concrete, masonry and other structural elements. When a concrete slab is stressed by the post tensioning method, it means the steel is being tensioned and the concrete is being compressed. 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. Economically design post tensioned and reinforced concrete floors including slabs, mats, and rafts, with exceptional visibility into compliance, efficiency, and practicality. Posttensioned, reinforced concrete slab design software ram. Fundamentals of posttensioned concrete design for buildings part one. Tributaries used when computing average precompression. Page 2 of slab post tensioning technical document system main features the advantages of the technique of slab post tensioning are several and clear. Nov 25, 2008 post tensioning is done onsite by installing post tensioning tendons within the concrete formwork in a manner similar to installing rebar. Tendon profile of a continuous post tensioned beam. The default load combinations for post tensioning are defined in the following sections.
Fundamentals of posttensioned concrete design for buildings. Uniformthickness slabs are typically about 9 inches thick throughout, except at the. This course is intended to be an introductory course for structural engineers new to post tensioned. Post tensioning tendon installation and grouting manual fhwa. Posttension basics how posttensioned slabs are built. Course content this spreadsheet program provides for the design and analysis of post tensioned concrete oneway beam and slab systems and twoway flat plate slab systems. 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. Stronger, more efficient floor slab design creates longer spans and reduces the need for columns within the structure. Post tensioning is a special form of prestressed concrete in which the prestressing tendons are stressed after the concrete is cast. Oneway slabs normally design as a beam with cables running in the direction of the span at uniform centres. The design moment of the slab is modified for each design section to include the twisting moment of the same section woodarmer approximation.
Post tensioned slabs can be designed to be crack free and therefore waterproof slabs are possible. Design of posttensioned slabs posttensioning institute. Posttensioned pt slabs are typically flat slabs, band beam and slabs or ribbed slabs. Unless otherwise noted, all referenced table, figure, and equation numbers are from these books. Design elevated concrete slabs with or without post tensioning. 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. 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.
Tension concrete compressed shorter than it wants to be. For general design philosophy and analysis of post tensioned concrete, the reader should refer to pdhonline course s127. Thanks to lift slabs 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. Recommended practice for precast posttensioned segmental. Achievement of this objective depends upon careful design, detailing and construction. The loadbalancing method did away with the complexity of post tensioning design, which hindered its widespread adoption by structural engineers. General principales local zone design general zone design. Nevertheless, it may be pointed out here that post tensioning can also be of. Post tension slab advantages and disadvantages of post. Banded tendons when designing twoway, post tensioned slab systems, in addition to the code. The vsl post tensioned concrete slab on grade is cast in very large areas, often exceeding 2,500m 2 with no joints. Pre tensioning and post tensioning 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.
Posttension flat slab design example free download as pdf file. Tributary slab widths for equivalent frames aalami, b. The design steps for a post tensioned composite bridge girder were prepared with the help of several sample design calculation demonstrated. Pre tensioning is accomplished by stressing wires or strands, called tendons, to predetermined. For residential construction, tendons at 48 inches on center are common. In design examples they have covered all types of structures where pt is used including seismic diaphragm, slabs on grade and external post tensioning.
Post tensioned foundations can be used for these types of soils by using other rational design methods. A slab strip of unit width is analysed using simple beam theory. Tensioning force transfer by steelconcrete bond force transfer at end anchor strain compatibility and force equilibrium. Because this course is intended to illustrate simplified analysis methods, we will use the efm exclusively. It provides an architect the freedom to work freely with his designs. For post tensioned concrete design, the user can specify the prestressing load pt by providing the tendon profile. 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.
Post tensioning is a method of reinforcing strengthening concrete or other materials with highstrength steel strands or bars, typically referred to as tendons. Posttensioned tendons are stressed after concrete is cast and hardened. 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. The prestressed concrete design of a structure is influenced by either of the two processes, pre tensioning, and post tensioning. Chapter 9 design of post tensioned slabs onground, p.
Part three continues with the study of twoway, post tensioned slab systems, including. Posttensioned concrete design spreadsheet program a pdh. Longer spans can be achieved due to prestress, which can also be used to counteract deflections. Post tensioning in buildings is not limited to floor slabs. If we take as an example a car parking, we can see that, in the case of simply reinforced concrete slab, the structure is made of a forest of pillars, with floor thickness considerably high. This hybridisation helps achieve the formation of a much thinner slab with a longer span devoid of any columnfree spaces. Schematic comparing a conventially reinforced concrete member to a post tensioned membaer. Specialised post tensioning flooring systems construction. Difference between pretensioning and posttensioning. Post tensioned pt concrete floors are now widely used in the uk, particularly for highrise buildings. We therefore apologize for the odd lapse into commercialism. Crack free performance vsl post tensioning axially compresses the concrete slab to counteract tensile stresses which. The tensile face indicates what portion of the beam requires reinforcing for strength. The following example illustrates the design methods presented in aci 31805 and ibc 2003.