The program is developed around the robust computational core of two popular programs ptdata. General after making an initial selection of the slab thickness, the second step in slab design is to determine the amount and distribution of prestress. Using the shear design method found in the pci design handbook precast and prestressed concrete 6th edition, the shear values were calculated at 3 ft, 8 ft, 12 ft and 18 ft from the support. In all the chapters, both bonded and unbundled post tensicmng will be dealt with. In addition to general design guidance and information on detailing practices, this section contains three design examples. 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. Framing dead load selfweight superrimposed dead load 25 psf partitions, me, misc. For example, an 8inchthick slab is typical for a 30footlong floor span 30 feet x 12 inchesfoot 45 8 inches. Structural calculations for posttensioned beam and oneway. 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. 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. Structural calculations for posttensioned flat slab. Sep 09, 2016 course study on post tension slab design.
This spreadsheet program provides for the design and analysis of post tensioned concrete oneway beam and slab systems and twoway flat plate slab systems. Post tensioned slabs use highstrength tensioned steel strands to compress the slabs, keeping the majority of the concrete in compression. In this free webinar dirk bondy and bryan allred discusses the latest edition of their book, posttensioned concrete principles and practice. We therefore apologize for the odd lapse into commercialism. The first two loss calculation methods on the form can be used to specify the prestress losses. Pt slabs offer the thinnest slab type, as concrete is worked to its strengths, mostly being kept in compression. Post tension analysis shear strength using the shear design method found in the pci design handbook precast and prestressed concrete 6th edition, the shear values were calculated at 3 ft, 8 ft, 12 ft and 18 ft from the support. The program is divided into three separate screens, which correspond to the three major areas of concern in the design of a post tensioned. This article provides information on how to scheme a pt slab and how the use of post tensioning affects the rest of the structure. Guidelines for the design of posttensioned floors by bijan o. This report presents the structural engineering calculations of a post tensioned floor using parallel beams and oneway slab construction. Pt designer is a computer program for the design and analysis of linear post tensioned concrete floor systems. The soil below the foundation is expansive clay with properties determined by the soil engineer.
Twoway posttensioned design amsysco post tensioning. Because this course is intended to illustrate simplified analysis methods, we will use the efm exclusively. This design example was not intended to follow the design and detailing practices of any particular agency. It was actually the widespread use of the posttensioned slabonground which induced this interest in design procedure and in many studies of reported slab failures. Includes powerpoint picture presentation of examples of post tensioning from my projects. This report presents the structural engineering calculations of a posttensioned floor using parallel beams and oneway slab construction. Fundamentals of posttensioned concrete design for buildings part one. Post tensioning in buildings is not limited to floor slabs. The anchorages to post tensioned members must distribute a large load to the. The following example illustrates the design methods presented in aci 31805 and ibc 2003. Slab onground design by using the pti ken bondy method. Horizontal post tensioned connections for precast concrete loadbearing shear wall panels 64 robin l. Design method may not be used for twoway, post tensioned slab systems. 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.
Comprehensive design example for prestressed concrete. 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. The file extension pdf and ranks to the documents category. Part three continues with the study of twoway, post tensioned slab systems, including. Developers, architects, engineers, contractors, educators and. For posttensioned concrete design, the user can specify the prestressing load. Pdf new methods in efficient posttensioned slab design using. The execution of the design will be explained with reference to an example.
Members of the institute include major post tensioning material fabricators in the u. Because of post tensioning s ability to balance loads and greatly reduce service load deflections, there is a 25 percent to 35 percent reduction in slab thickness in post tensioned structures compared with mild reinforced. Net, which many engineers have come to trust over the years for its accuracy and flexibility. While using this method more precautions has to be made for shear and deflection criteria for the slabs. Written by structural engineers who design post tensioned concrete buildings for a living and teach how to design them at the university level, there has simply never been anything like this book. Banded tendons when designing twoway, post tensioned slab systems, in addition to the code. The example presented here is for twoway posttensioned design. Tributary slab widths for equivalent frames aalami, b. 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. Ccl posttensioned slabs can bring unique freedom over conventional building methods. Comprehensive design example for prestressed concrete girder. A more detailed guide to the design of pt floors can be found in the concrete societys technical report 43 tr43. The following table of prestress losses is recommended for the design of post tensioned members, and does not include friction.
Structural calculations for posttensioned beam and. Equivalent tensile stress design appendix 5 examples using shrinkagecompensating concrete, p. Caprani post tensioned in this method, the concrete has already set but has ducts cast into it. Use the download button below or simple online reader.
This cantilevered golf course green is actually a post tensioned concrete slab. Longer spans can be achieved due to prestress, which can also be used to counteract deflections. The recommendations derived from these and other studies vary from extremely light to extremely heavy. Fundamentals of posttensioned concrete design for buildings part one a. An example of the aforementioned topology optimization. At the same time, the post tensioning selected was not to be less than the value necessary for lightly reinforced slabs to meet. Pdf analysis and design of rcc and posttensioned flat slabs.
Unless otherwise noted, all referenced table, figure, and equation numbers are from these books. Stronger, more efficient floor slab design creates longer spans and. In addition, already built structures will be described. Load balancing is used, a portion of the load on slab is balanced by the transverse forces imposed by the draped. This report is intended to serve as a manual of good practice for the design of prestressed concrete flat slabs in addition to the recommended procedures, other methods are described for the sake of completeness and to compare different methods of design. Post tensioned pt slabs are typically flat slabs, band beam and slabs or ribbed slabs. 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. Posttension flat slab design example prestressed concrete.
Post tensioned foundations in areas of high seismic risk for example, ibc categories d, e, and f or ubc zones 3 and 4 should conform to the appropriate seismic prono 2. Tensioning building structures march 12, 2020 2020 educode las vegas. Fundamentals of post tensioned design for buildings. General principales local zone design general zone design. This is the structural calculation of the post tensioned ground supported foundation slab of sunshine building. Horizontal posttensioned connections for precast concrete. The behavior of post tensioned flat plates in the critical column area is of great concern to designers. Post tensioned pt concrete floors are now widely used in the uk, particularly for highrise buildings. 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. Pt designer is a computer program for the design and analysis of linear posttensioned concrete floor systems.
To get the excel sheet join as loving fansub member to this channel. Posttension basics how posttensioned slabs are built. Pt designer design of posttensioned concrete floors. Aug 30, 2017 this spreadsheet program provides for the design and analysis of post tensioned concrete oneway beam and slab systems and twoway flat plate slab systems. This web seminar focuses on the design of post tensioned two way flat slabs that can be used for a multitude of building applications ranging from parking, hotel, office and podium type structures. Pt slabs castinplace beams, slabs and columns liquid retaining and containment structures beams and design strips of post tensioned slabs xy and xz projections of design strips with post tensioned tendon safe and comprehensible fast and optimized design of reinforcement is not limited to necessary areas. Design method may not be used for twoway, posttensioned slab systems. This design should always be used unless approval to use a thinner deck is obtained from the state bridge engineer. Post tensioned concrete design for aci 31808 contents. The design of posttensioned flat slab can be done by. This hybridisation helps achieve the formation of a much thinner slab with a longer span devoid of any columnfree spaces.
Post tension design of slab there is document post tension design of slab available here for reading and downloading. For economical design of similar structures a smaller slab thickness leading to values between 60% to 80% of balanced selfweight is generally selected. The strands or tendons are fed through the ducts stage 1 then tensioned stage 2 and then anchored to the concrete stage 3. The example selected represents a frame of a one way slab and beam. Many post tensioned slabs will be stamped to alert the owner and any renovation contractors that the slab is post tensioned. Fundamentals of posttensioned concrete design for buildings part one a suncam online continuing education course. In part two, we worked several examples of two of the structural systems commonly used in.
A post tensioned countertop can support a lot of weight. Tendon profile of a continuous post tensioned beam. M ed is that part of the unbalanced slab bending moments that is transferred into the column at the support. Tensioned slabs with unbonded tendons publication establish consistent sign convention for gravity loads and primary moment, pe preliminary design spandepth ratio source. The example presented here is for twoway post tensioned design.
Unfortunately, specific design provisions for shear strength and flexural strength of unbonded prestressed slabs are not provided in the present aci code aci 31871. The program is divided into three separate screens, which correspond to the three major areas of concern in the design of a post tensioned member. Equivalent tensile stress design appendix 5examples using shrinkagecompensating concrete, p. Tensioning building structures miroslav vejvoda, p. In addition to the already mentioned general features of post tensioned construction, the following.
From the design criteria, the posttensioned slab is designed for a uniformly distributed superimposed dead load of 3. Post tensioned concrete design for aci 31808 slabstitch. This book is destined to become the definitive work on the design of post tensioned concrete buildings for many decades to come. 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.
The following table of prestress losses is recommended for the design of post tensioned members, and does not include friction or wedge set losses. Fundamentals of posttensioned concrete design for buildings. The design follows the pti ibc, ubc recommendations, with enhancements where necessary epti. For most projects, conventional materials should be specified. Post tension slab working principle, components and. Post tensioning for twoway flat plate construction figure 2.
The general criteria used for the design, such as details of material. The design is based on hong kong building code hkcop 2004 and its amendment of june 2007. Originally post tensioned, twoway slab framing systems were constructed with column and. This course is intended to be an introductory course for structural engineers new to post tensioned. General principales local zone design general zone design examples from pratice published by. Posttensioned concrete design spreadsheet program a pdh. The following graph in figure was made to show the shear distribution along the post tensioned slab. Posttension flat slab design example free download as pdf file. General overview of posttensioned concrete design instructor. Tn342 design example 2way mondada 093090 adapt corporation.
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