Lorman offers professional resources regarding COVID-19 and the 2020 Election

Post-Tensioned Buildings

» Articles » Construction Articles » Article

January 23, 2009

Buildings with monostrand unbonded tendons post-tensioned slabs are becoming a widely used application of prestressed concrete. This method achieves performance and construction improvements over other construction methods. However, in order to reap the benefits of this method, proficiency is required in both structural design and construction.

Post-tensioned slabs is a preferred method for industrial, commercial and residential floor slab construction. The increasingly extensive use of this method is due to its advantages and its nature of easy application to a wide variety of structure geometry and design solutions.

Prestressed floor systems using monostrand tendons may be designed as either one- or two-way slab systems, and may be flat plate, flat slab waffle slab or other slab sections. The prestressing is achieved by individually tensioning tendons, placed within internally greased protected plastic sleeves, arranged in the slab prior to casting. Compressive stresses are applied to the concrete via tendon anchors. Prestressing is performed within three to seven days of casting.

Unlike the multistrand system (which is primarily suited for beams and girders) the monostrand method allows prestressing of slabs as thin as 15 centimeters while maintaining vertical optimal curvatures for the structure. The monostrand system is also simpler, requires less in site organization and is more forgiving to construction variances.

Continue reading below

FREE Construction Training from Lorman

Lorman has over 34 years of professional training experience.
Join us for a special live webinar registration and level up your Construction knowledge!

Advancement of Women in Construction - Feb 24, 2021
Presented by Karla Smalley and Ellen Dickson

Learn More

Advantages afforded by unbonded slab prestressing as compared with alternative designs include:

Increased speed of construction as prestressing allows for faster stripping and reuse of formwork. Thinner slabs resulting from post-tensioning by virtue of improved deflection behavior and improved section utilization.
Improved economy due to reduced slab thickness and associated concrete costs, reducing building weight with the corresponding foundation reductions, reduced building height with the corresponding decrease in building skin area and a reduced amount of mild reinforcing rebar. Large area slabs can be maintained with no control joints. Simpler coordination between consultants due to a flat slab underside; the design and installation of utilities systems is simpler (heating, air conditioning, sprinklers, etc.). Increased design flexibility allows simple solutions even for structures with irregular geometry, without the need for transverse or longitudinal beams. Longer spans can be achieved improving the architectural structure flexibility. Long-term deformations due to creep, which are usually significant in concrete slabs, are almost nonexistent in unbonded tendons prestressed slabs. Longer building life cycle due to the uncracked nature of the prestressed concrete. This advantage also creates slabs more resistant to water penetration, and the structure behaves monolithically. Post-tensioned slab on grade - by post-tensioning, large area of slab on grade for any propose, can be designed without any joint, improving performance of the slab, increasing life span and reducing maintenance cost.

Typical projects are listed at www.yde.co.il/Post-Tensioned-Buildings.aspx.

The material appearing in this web site is for informational purposes only and is not legal advice. Transmission of this information is not intended to create, and receipt does not constitute, an attorney-client relationship. The information provided herein is intended only as general information which may or may not reflect the most current developments. Although these materials may be prepared by professionals, they should not be used as a substitute for professional services. If legal or other professional advice is required, the services of a professional should be sought.

The opinions or viewpoints expressed herein do not necessarily reflect those of Lorman Education Services. All materials and content were prepared by persons and/or entities other than Lorman Education Services, and said other persons and/or entities are solely responsible for their content.

Any links to other web sites are not intended to be referrals or endorsements of these sites. The links provided are maintained by the respective organizations, and they are solely responsible for the content of their own sites.