For post tensioned concrete bridges we need the construction stages for the evaluation of different cross section properties based on the open and filled ducts for the tendons as well as for creep and shrinkage analysis. The importance of posttensioned bridges to hong kong. Masonry walls can be post tensioned this is usually done with a solid steel bar fastened to the foundation and stressed with a nut at the walls top. Forensic testing of post tensioned concrete girders. Project awards 10 august 2017 pti journal girders and a twostory post tensioned concrete truss was designed to span the full 120 ft 37 m. The anchorages to post tensioned members must distribute a large load to the concrete, and must resist bursting forces as a result. Unless otherwise noted, all referenced table, figure, and equation numbers are from these books. We therefore apologize for the odd lapse into commercialism.
The system can be configured in shortspan, twoway slabs or in longspan, beam and slab systems. Posttensioned concrete s tructures university of illinois. A definition should clarify which type of post tensioned residential and light commercial slabsonground is intended to be excluded from the aci 318 building code. Pdf prestressed and posttensioned concrete yatniel. Posttensioning is simply a way to reinforce in a more active way. Longer spans can be achieved due to prestress, which can also be used to counteract deflections. Posttensioned pt slabs are typically flat slabs, band beam and slabs or ribbed slabs. Posttensioning methods for reinforcing concrete the.
Post tensioned concrete is a very common type of concrete structure for parking garages today and can be constructed below grade or above grade. Allowable deflection limits refer to table 1 of the appendix. In certain applications, slabs in the order of 10,000m 2 have been constructed without movement joints. 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. All books are in clear copy here, and all files are secure so dont worry about it. The above spreadsheet program and users manual can be downloaded and be printed free of charge. Post tensioned concrete beam bridge sofistik tutorials 2020. In addition, post tensioned slabs are stiffer showing less deflection under load and are. Variable prestress force in unbonded posttensioned members, concrete international, january 1992, pp. These foundations will typically contain less reinforcement prestressed and. Pt designer design of posttensioned concrete floors.
This is part two of a threepart course that covers the fundamentals of post tensioned concrete for building structures using unbonded tendons. Post tensioned in this method, the concrete has already set but has ducts cast into it. Pt designer builds upon that by incorporating a userfriendly interface and attractive pdf outputs for a more efficient use of the program. The vsl post tensioned concrete slab on grade is cast in very large areas, often exceeding 2,500m 2 with no joints. Graduate research assistant, stru ctural systems laboratory, dep t. Posttensioned concrete foundations designed by thi s standard generally meet the requirements for plain concrete specified in chapter of aci 31814 14 1. Download free, highquality cad drawings, blocks and details of posttensioned concrete organized by masterformat. Kindle file format pti post tensioning manual 6th edition. The software is extremely easy to use and is intended for both occasional and regular designers of post tensioned concrete floor systems. Project awards 10 august 2017 pti journal girders and a twostory posttensioned concrete truss was designed to span the full 120 ft 37 m. Tensioning force transfer by steel concrete bond force transfer at end anchor strain compatibility and force equilibrium. As such, it is intended that this standard be independent of aci 318 and the conflicting parts of the general building code.
In pretensioned and post tensioned members, applying prestressing force causes shortening of the concrete member that, in turn, causes a loss of tendon stress. The most common structures in hong kong are multispan concrete viaducts more than 30% of these structures are posttensioned most of the large span landmark concrete structures are posttensioned posttensioned bridges are vitally important elements. Design of rectangular openings in unbonded posttensioned precast concrete walls structural engineering research report department of civil engineering and geological sciences university of notre dame notre dame, indiana april 2001 michael allen and yahya c. 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 posttensioned concrete members. Concrete for castinplace posttensioned box girder bridges shall have initial and final concrete strengths as specified in the table below. For these applications, it is possible to develop a load in a macalloy bar up to 25% of the characteristic failure load, by applying a predetermined torque to the macalloy nut.
Posttensioning tendons, which are prestressing steel cables inside plastic ducts or sleeves, are. The companies that make prestressed concrete tanks are crom, dyk, natgun, and preload. Effective inspection and monitoring of posttensioned structures. General principales local zone design general zone design. Notice the assumptions required for the post tensioned design fig. Bekaert strands achieve excellent fatigue strength, allowing for innovative installation design. Insert the ssd tasks csm and fill in the stages as defined in table construction stages above.
The following example illustrates the design methods presented in aci 31805 and ibc 2003. Post tensioning is used in this manner in millions of square feet of warehouse floors, sport courts, housing and specialized paving applications. Anchorages provide for the safe introduction of post tensioning forces into the concrete. Net is a windowsbased computer program for the design and analysis of linear post tensioned concrete frames. Kang has taught post tensioned concrete structures courses at many universities such as ucla, the univ. Different from conventional systems that use monolithic cast in place reinforced concrete coupling beams or embedded steel coupling beams, the nonlinear behavior of post tensioned precast concrete coupling beams is governed by the ope ning of gaps at the. In corrosive environments, stuffed and heatsealed tendons have the inherent shortcoming of either trapping or allowing access of corrosive substances in the oversized sheathing. In general, post tensioned concrete elements require less concrete and steel reinforcement than their reinforced concrete counterparts to achieve the same load bearing capability resulting in a reduction in the cost of materials. The concrete convention and exposition major modifications chapter 9 posttensioning 1. Center for advanced infrastructure and transportation utah state. Posttensioned foundations can be used for these types of soils by using other rational design methods. Twoway posttensioned design amsysco post tensioning.
Posttensioned slabs prestressed concrete cclint pdf. Tension concrete compressed shorter than it wants to be. Concrete water tanks are often post tensioned to reduce crack width and leakage. Coupling of concrete walls using post tensioned precast. Draped harped profiles temporarily held in place before concrete is hardened debonding not all strands are active at end of span strategies for post tensioned systems. Concrete strengths greater than the maximum limit may only be used when required by design and approved by adot materials and bridge groups. They are typically supported on concrete columns and perimeter foundation walls. Clarified specifications for personnel qualifications 2. Read online posttensioned slabs prestressed concrete cclint book pdf free download link book now. The strands or tendons are fed through the ducts stage 1 then tensioned stage 2 and then anchored to the concrete stage 3.
Information from its description page there is shown below. Tributaries used when computing average precompression. Unbonded post tensioning system technology in building construction 123 fabrication of monostrand sheathing was supplied until the early to mid1990s. Pt slabs offer the thinnest slab type, as concrete is worked to its strengths, mostly being kept in compression.
Forensic testing of post tensioned concrete girders 6. Post tensioning was used in the top and bottom chords of the truss to help. Such a strength outside the range shown in section 4061. Coupling of concrete walls using post tensioned precast concrete beams brad d. Unbonded post tensioning system technology in building. It is based on the recommendations of aci318 as expounded in adapt technical note tn292. Section 4loss of prestressemphasis on items specific to post. Schematic comparing a conventially reinforced concrete member to a post tensioned membaer. Crack free performance vsl post tensioning axially compresses the concrete slab to counteract tensile stresses which.
Mar 11, 2019 download posttensioned slabs prestressed concrete cclint book pdf free download link or read online here in pdf. The objectives of this research are to determine the secondary moment of post tensioned concrete flat plates, to provide design aid charts regarding this secondary moment, and to investigate the effect of the. Over time, concrete creep, concrete shrinkage, and steel relaxation result in additional reductions of tendon stress. Commons is a freely licensed media file repository. Posttensioned concrete design spreadsheet program a pdh.
Residential and light commercial post tensioned concrete shallow foundations on expansive soils are ribbed or uniformthickness post tensioned foundations built on expansive soils. Post tensioning is a technique for reinforcing concrete. We manufacture our steel 7wire strands with expertise in compliance with astm, pti and fib standards. Download free, highquality cad drawings, blocks and details of post tensioned concrete organized by masterformat. Post tensioning terminology ptt november 20 page 2 of 33 bearing plate, basic flat steel plate that transfers the tendon force directly into the concrete, meeting the analytical design requirements of pti acceptance standards for post tensioning systems, section 3. Pdf posttensioned concrete girders yatniel bustamante. Pt designer is extremely easy to use and is intended for both occasional and regular designers of posttensioned concrete floor systems. For lightweight concrete, the air dry unit weight shall be shown on the plans as 119 lbft.
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