Interior left, exterior right deflection analysis the final consideration in the design of the twoway slabs is deflection. 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. Tendon layout, including dimensions, which locates the tendons in the horizontal plane. Aalami a must have reference book for engineers, students, contractors, building officials, and researchers. Unless otherwise noted, all referenced table, figure, and equation numbers are from these books. Jurgens his article presents a set of guidelines intended to t assist designers in routine post tensioning design. A normal slab is basically a rcc reinforce cement concrete slab where as a post tentioned slab is the psc prestressed concret slab. This video tutorial is about pts post tension slab design which is trained by master of structural engineering mr. In 1980 fip had published recommendations for the design of flat slabs in posttensioned concrete out of print already for many years. This lab manual was prepared with the help of the renowned text book design of prestressed concrete structures, 3rd edition by t. This is part two of a threepart course that covers the fundamentals of post tensioned concrete for building structures using unbonded tendons. Deflecuon limits prestressing in posttensioned slabs fundamentally influences the behaviour of the structure under service loads.
Balcony slabs in typical post tension buildings with balconies, the balcony slab is an extension of the concrete. For residential construction, tendons at 48 inches on center are common. The program is divided into three separate screens, which correspond to the three major areas of concern in the design of a post tensioned. Experimental and numerical assessment of bonded and unbonded post tensioned concrete members. Framing dead load selfweight superrimposed dead load 25 psf partitions, me, misc. Tn342 design example 2way mondada 093090 adapt corporation. It took until the 1920s and 30s for its materials development to progress to a level where prestressed concrete could be used with confidence. Soils are wetter at slab edge than at any point inside. The project scope consists of design and plan preparation for a 3span, posttensioned concrete haunched slab bridge, referred to by the kdot bridge superstructure log code as xcsh in this manual. In this video, he will describe his experiences at the site as.
Because this course is intended to illustrate simplified analysis methods, we will use the efm exclusively. Less concrete and steel are needed for the same structural capacity and the slab stiffness is increased so that the slab is better able to resist bending caused by differential soil movements. Post tension slab working principle, components and. In the present study the design of the posttensioned flat slab is done by using both methods, load balancing. Joint aciasce committee 352 is therefore currently revising aci. Originally post tensioned, twoway slab framing systems were constructed with column and. Fundamentals of posttensioned concrete design for buildings part one. Reinforced and posttensioned concrete slab design software. University of houston master construction specifications insert project name ae project number. Posttensioned pt slabs are typically flat slabs, band beam and slabs or ribbed slabs. This course is intended to be an introductory course for structural engineers new to post tensioned concrete design, and is a good refresher for experienced structural engineers. Given the widespread use of pt flat plate systems in the u. Environmental impact assessment of post tensioned and conventional reinforced concrete slab design dane miller1, jeunghwan doh and tim peters2 1griffith school of engineering, griffith university, gold coast, australia 2adg engineering, gold coast, australia this research determines environmental advantages achievable through application of.
The following table of prestress losses is recommended for the design of post tensioned members, and does not include friction. This spreadsheet program provides for the design and analysis of post tensioned concrete oneway beam and slab systems and twoway flat plate slab systems. Reports on an analysis of 18 full scale fire tests of concrete slabs and beams prestressed by post tensioning. To provide a complete idea, the stress computation, the reinforcement detailing, shear design, the jacking procedure etc. Construction maintenance of post tensioned slab on ground. Experience and expertise gained from working on projects.
Post tensioning will reduce cracking and keep any cracks that might. The materials to be used are grade c25 concrete and grade 500 reinforcement. Reinforced concrete design 1 design of slab examples. Gregory havel takes a look at this aspect of modern building construction. Load balancing is used, a portion of the load on slab is balanced by the transverse forces imposed by the draped. Post tensioned slabs are intrinsically waterproof and. Advantages of using post tensioning for your next slab onground project. Analysis of posttensioned flat slab by using safe shriraj s.
Achievement of this objective depends upon careful design, detailing and construction. Part three will continue with the study of twoway, post tensioned slab systems, including a design example using the equivalent frame concept. Cables are arranged as indicated by the engineer and chaired to run through the center of the slab. Post tension design of slab there is document post tension design of slab available here for reading and downloading. The design steps for a two way post tensioned slab. Threedimensional 3d finite element software for the integrated analysis and design of concrete and posttensioned floor and foundation systems. Pt slabs offer the thinnest slab type, as concrete is worked to its strengths, mostly being kept in compression. Attempts were made to improve knowledge by in depth theoretical studies and experiments on posttensioned plates. Post tensioned concrete is accomplished by tensioning high strength steel cables within the concrete mass. This article provides information on how to scheme a pt slab and how the use of post tensioning affects the rest of the structure.
Posttensioned twoway slab pennsylvania state university. In this free webinar dirk bondy and bryan allred discusses the latest edition of their book, post tensioned concrete principles and practice 3rd edition as well as present the latest version. There are several problems that can occur with post tensioning components in balcony and garage slabs in service. This is part three of a threepart course that covers the fundamentals of post tensioned concrete for building structures using unbonded tendons.
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. The commentary is provided to mention the considerations of the committee in developing the criteria. Fundamentals of post tensioned design for buildings. The idea of prestressed concrete has been around since the latter decades of the 19th century, but its use was limited by the quality of the materials at the time. Post tensioned concrete is used more frequently today than in the past, and presents several hazards to firefighters. This method is achieved in a process where metal or plastic tubes which contain loose tensioning cables or rods are cast into the concrete. What is the difference between normal slab and posttensioned. Posttensioning software post tensioning software builder floor pro. Nonprestresed bonded reinforcement in posttensioned building design pdf.
The choice of concrete mix and curing methods along with quality workmanship also play a key role. Post tensioned buildings design and construction bijan o. Fundamentals of posttensioned concrete design for buildings. The design of the post tension flat slab can be done by using load balancing. Post tensioning in buildings foreword working party wp1. Use the download button below or simple online reader. Jan 24, 2015 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 as post tension slab. General overview of post tensioned concrete design instructor.
There are four 4 span arrangements and five 5 roadways plus one 2 offset crown roadway for each span arrangement included in the manual. Construction of post tensioned slabs on grade is very similar to using reinforcing steel, except for the tensioning step. A 5inch post tensioned slab can handle up to 5,000 pounds, and a typical 9inchthick slab will bear a concentrated 9,000pound load. 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. Joint efforts by researchers, design engineers and. Part three also covers related topics such as punching shear for twoway slabs and moment transfer at the column. In addition, both the international building codeand the uniform building codeprovide design methods for determining the capacity of a post tensioned slab to. The example presented here is for twoway post tensioned design. When the concrete reaches a certain design strength, the cables are then tensioned to a pre. 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.
The behavior of post tensioned flat plates in the critical column area is of great concern to designers. The main objective of the bulletin is to point out the benefits of using post tensioning for. The following example illustrates the design methods presented in aci 31805 and ibc 2003. Post tension slab advantages and disadvantages of post. Design method may not be used for twoway, post tensioned slab systems. Part three is an exampleintensive course, with key concepts introduced along the way. Indications are given concerning preliminary design and indirect control of deflections in posttensioned flat slabs. Post tensioned slabs can be designed to be crack free and therefore waterproof slabs are possible. A psc is applied with a compressive stress on the cross section in advance before the application of loading on. 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. University of houston master construction specifications. Transmission forces reinforcement reinforcement transverse tension.
The following table of prestress losses is recommended for the design of post tensioned members, and does not include friction or wedge set losses. It is the intent of this chapter to establish the practices and specific requirements of the structure and bridge division for the design and detailing of prestressed and post tensioned concrete members. Post tensioned pt concrete floors are now widely used in the uk, particularly for highrise buildings. The slab is outside buildings which subjected to 1 hr fire resistance and design for 50 years design life.
In post tensioned floor slab construction, the placement of post tensioning tendons and associated nonprestressed. For professionals engaged in posttensioning design. 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. Mar 27, 2017 this video tutorial is about pts post tension slab design which is trained by master of structural engineering mr. Three post tensioned slabs with unbounded tendons were designed figures 4 and 5. Guidelines for the design of post tensioned floors by bijan o. Fundamentals of post tensioned concrete design for buildings part one. A more detailed guide to the design of pt floors can be found in the concrete societys technical report 43 tr43. This model specification offers guidance to organisations. Where design requirements demand more reinforcement that is generally assigned to a typical interior waffle stem, solid strips along the lines of.
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. Users manual posttensioned concrete haunched slab bridges. Post tensioning in buildings is not limited to floor slabs. Banded tendons when designing twoway, post tensioned slab systems, in addition to the code.
Unfortunately, specific design provisions for shear strength and flexural strength of unbonded prestressed slabs are not provided in the present aci code aci 31871. Ccl carries out complete designs for posttensioned concrete applications. 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. Dec 24, 2014 objectives the objective of the present report is to summarize the experience available today in the field of post tensioning in building construction and in particular to discuss the design and construction of post tensioned slab structures, especially post tensioned flat slabs a detailed explanation will be given of the checks to be carried.
In addition, results of tendonanchor assembly tests performed at high temperatures. Detail horizontal curvature of tendons at blockouts, openings and. In 1980 fip had published recommendations for the design of flat slabs in post tensioned concrete out of print already for many years. Longer spans can be achieved due to prestress, which can also be used to counteract deflections. Post tensioned slabs use highstrength tensioned steel strands to compress the slabs, keeping the majority of the concrete in compression.
Twoway posttensioned design amsysco post tensioning. 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. Posttension basics how posttensioned slabs are built the. A design strip is a region assigned to a hypothetical support line that joins a line of columns and. Salunke mgms college of engineering and technology, kamothe, india mgms college of engineering and technology, kamothe, india abstract the use of posttensioned flat slab is increasing day by day, due to its advantages over traditional concrete. This tension makes the concrete slab and foundation much stronger than concrete without reinforcement and helps reduce cracking. 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. Model specification bonded and unbonded posttensioned.
The file extension pdf and ranks to the documents category. This lab manual was prepared with the help of the renowned text book design of. Posttensioned concrete design spreadsheet program a pdh. Posttension basics how posttensioned slabs are built. 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. The recommendations derived from these and other studies vary from extremely light to extremely heavy.
Pdf experimental and numerical assessment of bonded and. Developers, architects, engineers, contractors, educators and. But while using this method more precautions has to be made for the shear and the deflection criteria for the slabs. 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. The execution of the design will be explained with reference. New developments in structural engineering and construction.
According to adoss, the interior spans due not meet the code requirements to neglect deflection. For economical design of similar structures a smaller slab thickness leading to values between 60% to 80% of balanced selfweight is generally selected. 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. The advantages of the technique of slab post tensioning are several and clear. The behaviour and response of flat slab and post tensioned flat slab during earthquake is an important aspect which needs to be explored. This slab is much stronger as well as more durable than the normal concrete slabs. Design a spread footing using 3000 psi normal weight concrete and grade 60 bars.
Pdf prestressed and posttensioned concrete yatniel. The pti design procedure is used to design a slabon grade foundation that will respond. This article will explore features of posttensioned concrete. Fundamentals of post tensioned concrete design for buildings part one a suncam online continuing education course. Brendon burley structural option post tensioned twoway slab figure 23 details of the twoway slab.
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