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