Standard requirements for design and analysis of shallow posttensioned concrete foundations on expansive and stable soils ballot end date. 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. Fundamentals of posttensioned concrete design for buildings part one. 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. Course content this spreadsheet program provides for the design and analysis of posttensioned concrete oneway beam and slab systems and twoway flat plate slab systems. Slabonground posttensioned slabsonground provide a costefficient, highperformance solution for problems associated with groundsupported residential foundations on shrinkswell soils. The compressive stresses resist the anticipated tension stresses induced by the soil movements, enhancing the performance over a nonprestressed foundation. After a highly successful first run, the post tensioning institutes design and construction of post tensioned slabson ground has been extensively revised. A more detailed guide to the design of pt floors can be found in the concrete societys technical report 43 tr43. This video tutorial is about pts post tension slab design which is trained by master of structural engineering mr. Tensioning building structures march 12, 2020 2020 educode las vegas. Ribbed slabs there are two basic types of posttensioned residential slabs. Slab post tensioning systems page 5 38 reinforcing savings as steel and concrete increase in pricing, the savings with a post tensioned slab will increase, because the quantity of steel and concrete required for a post tensioned slab is less than for a conventionally reinforced foundation. Posttensioned 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 tensioning concrete increases the many benefits associated with a concrete framed building. The soil below the foundation is expansive clay with properties determined by the soil engineer. It was actually the widespread use of the post tensioned slab on ground which induced this interest in design procedure and in many studies of reported slab failures. Originally post tensioned, twoway slab framing systems were constructed with column and middle strips, similar to those used in conventionally reinforced twoway slabs. Chapter 9 design of post tensioned slabs on ground, p.
As long as the slab remains ground supported and is free to shorten during stressing, the post tensioning force will result in a uniform precompression in the majority of the slab, regardless of the tendon position and profile, or variations in the slab thickness. This course is intended to be an introductory course for structural engineers new to post tensioned. The design of a post tensioned slab on grade must address the effects of both applied loads and imposed deformations. Details improving the constructability of post tensioned floors 27 7. Slab posttensioning systems page 5 38 reinforcing savings as steel and concrete increase in pricing, the savings with a post tensioned slab will increase, because the quantity of steel and concrete required for a posttensioned slab is less than for a conventionally reinforced foundation. These design elements must be enlisted and added in the contract documents by the designer in charge before asking for a bidding.
Slab on ground design by using the pti ken bondy method. Details improving the constructability of posttensioned floors 27 7. This course is intended to be an introductory course for structural engineers new to posttensioned. Since the books initial publication in 1980, it has been used by engineers and contractors to successfully design and construct hundreds of thousands of posttensioned slabs on ground. In the succeeding years numerous posttensioned slabs were designed and constructed in.
The recommendations derived from these and other studies vary from extremely light to extremely heavy. Pdf new methods in efficient posttensioned slab design using. By using posttensioned tendons to compress the concrete. Slab on ground post tensioned slabson ground provide a costefficient, highperformance solution for problems associated with ground supported residential foundations on shrinkswell soils. 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. 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.
A highly unique and valuable chapter is presented on construction issues and structural observations, and finally chapters addressing two of the more exotic applications of post tensioning, post tensioned slabson ground and externally applied post tensioning for strengthening and repair. For general design philosophy and analysis of posttensioned concrete, the reader should refer to pdhonline course s127. This is the structural calculation of the posttensioned ground supported foundation slab of sunshine building. For the specified concrete material of 40 mpa cube strength, this translates to tensile stresses exceeding 5. By using posttensioning method one can achieve the most economical and safe design for commercial as well as residential buildings.
Stronger, more efficient floor slab design creates longer spans and reduces the need for columns within the structure. Part three continues with the study of twoway, post tensioned slab systems, including. General overview of post tensioned concrete design. The design is sensitive to differing subgrade strengths and requires the slab to be isolated from the rest of the s tructure to allow unrestrained shrinkage movement of the slab. A highly unique and valuable chapter is presented on construction issues and structural observations, and finally chapters addressing two of the more exotic applications of posttensioning, posttensioned slabsonground and externally applied posttensioning for strengthening and repair.
The design of post tensioned flat slab can be done by using load balancing and equivalent frame method. Design methods are given for unreinforced concrete, reinforced concrete, shrinkagecompensating concrete, post tensioned concrete, fiberreinforced concrete slabson ground, and slabson ground in refrigerated buildings, followed by information on shrinkage and curling. The purpose of this publication is to widen the understanding of posttensioned 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. Slabonground design by using the pti ken bondy method. Economically design posttensioned and reinforced concrete floors including slabs, mats, and rafts, with exceptional visibility into compliance, efficiency, and practicality. Posttensioning institutes design of posttensioned slabsonground, pti design procedure 3rd edition. When zd is determined, the prestressing force required to balance an. The new and improved slabonground design manual concrete. 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.
Banded tendons when designing twoway, post tensioned slab systems, in addition to the code. Post tension slab working principle, components and. 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 posttensioned slab. This article provides information on how to scheme a pt slab and how the use of post tensioning affects the rest of the structure.
Download aci 360r10 guide to design of slabsonground pdf. The vsl hardware for use in building structures 23 4. Us posttensioning industry owes its existence to liftslab construction first liftslab 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. Cracking in groundsupported post tensioned slabs on. Posttensioning concrete increases the many benefits associated with a concrete framed building. A combination of these values will determine the slab stresses at the time of stressing and at service loads. Twoway posttensioned design amsysco post tensioning. Efficiency is especially apparent in multispan applications. As such, post tensioned slabsonground are exempt from ubc 1997 section 1806. 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 good source for more information is design and construction of post tensioned slabson ground post tensioning institute, phoenix, ariz 6028707540. Pdf analysis and design of rcc and posttensioned flat. Fundamentals of post tensioned design for buildings.
Oneway slabs normally design as a beam with cables running in the direction of the span at uniform centres. We therefore apologize for the odd lapse into commercialism. Pti 30 tendon p tan p w bal p tan p cgc e load w bal p wl2 8e m1 p e primary moment load balancing m2 secondary moment developed in post. However, because the continuous twoway tendons had to be placed in a draped parabolic profile near the top of. The design follows the pti ibc, ubc recommendations, with enhancements where necessary epti.
The design of a posttensioned slab on grade must address the effects of both applied loads and imposed deformations. Banded tendons when designing twoway, posttensioned slab systems, in addition to the code. The execution of the design will be explained with reference. The behaviour and response of flat slab and post tensioned flat slab during earthquake is an important aspect which needs to be explored. In any span, the max cable sag, zd depends on the concrete cover requirements and the tendon dimensions. For the application of design procedure an office building is considered as a case study. 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. In this video, he will describe his experiences at the site as.
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. Post tension slab advantages and disadvantages of post. This video tutorial is about pts posttension slab design which is trained by master of structural engineering mr. This spreadsheet program provides for the design and analysis of posttensioned concrete oneway beam and slab systems and twoway flat plate slab systems. Design floors and foundations reliably and efficiently, saving time and money, and overcoming the most common concerns you face as a. General principales local zone design general zone design. Ribbed slabs there are two basic types of post tensioned residential slabs. Since the books initial publication in 1980, it has been used by engineers and contractors to successfully design and construct hundreds of thousands of post tensioned slabs on ground. Longer spans can be achieved due to prestress, which can also be used to counteract deflections. Posttensioned concrete design spreadsheet program a pdh. Anchorages provide for the safe introduction of post tensioning forces into the concrete. Construction of posttensioned slabs on grade is very similar to using reinforcing steel, except for the tensioning step. Fundamentals of posttensioned concrete design for buildings. 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.
A slab strip of unit width is analysed using simple beam theory. 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. The design of posttensioned flat slab can be done by using load balancing and equivalent frame method. For residential construction, tendons at 48 inches on center are common. This article provides information on how to scheme a pt slab and how the use of posttensioning affects the rest of the structure. Black canyon highway suite 103 phoenix, arizona 85021 telephone. Originally posttensioned, twoway slab framing systems were constructed with column and middle strips, similar to those used in conventionally reinforced twoway slabs.
By using post tensioned tendons to compress the concrete, the formation of visible shrinkage cracks can be greatly. Posttensioned concrete foundations, designed in accordance with the pti method, qualify as designed footings in accordance with the ibc 2003 chapter 18, soils and foundations, and ubc 1997 chapter 18, foundations and retaining walls. Tensioning building structures miroslav vejvoda, p. Construction of slabs on ground design considerations aci.
The new 1996 edition reflects the industrys current. The design follows the pti ibc, ubc recommendations, with enhancements where. After a highly successful first run, the posttensioning institutes design and construction of posttensioned slabsonground has been extensively revised. The pti design procedure is used to design a slabon grade foundation that will respond elastically to forces the foundation is exposed to including those that are the consequence of soil pressure and soil deformation. 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. Fundamentals of posttensioned concrete design for buildings part one a suncam online continuing education course. A good source for more information is design and construction of posttensioned slabsonground posttensioning institute, phoenix, ariz 6028707540.
Because this course is intended to illustrate simplified analysis methods, we will use the efm exclusively. The program is divided into three separate screens, which correspond to the three major areas of concern in the design of a posttensioned member. It provides an architect the freedom to work freely with his designs. Design methods are given for unreinforced concrete, reinforced concrete, shrinkagecompensating concrete, posttensioned concrete, fiberreinforced concrete slabsonground, and slabsonground in refrigerated buildings, followed by information on shrinkage and curling. 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. Design method may not be used for twoway, posttensioned slab systems. Anchorages provide for the safe introduction of posttensioning forces into the concrete. Posttensioned, reinforced concrete slab design software ram. 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. Nov 25, 2008 post tensioned concrete is a term heard more and more in the construction industry today. Aalami, editor for professionals engaged in posttensioning design issue 6 august 1995 cracking in groundsupported posttensioned slabs on expansive soils by ken bondy1 1 introduction posttensioned slabs are widely used as foundations for light residential construction in areas of expansive soils. Pt slabs offer the thinnest slab type, as concrete is worked to its strengths, mostly being kept in compression. Posttension basics how posttensioned slabs are built the. Cables are arranged as indicated by the engineer and chaired to run through the center of the slab.