Benefits of post-tensioning concrete slabs in building

Post-tensioned concrete slabs in buildings provide various benefits over reinforced concrete slabs & other structural systems toward both single and multi-level structures. Described below, some of the advantages of the slabs :-

Longer Spans: Longer spans are utilized to lessen the number of columns. It leads to bigger, column free floor areas which significantly enhance the adaptability of application for the structure as well as leads to greater rental returns.

Entire structural cost: The complete cost of materials, labor and formwork which are essential to build up a floor is decreased for spans higher than 7 meters and consequently leads to huge cost savings.

Minimized floor to floor height: Thinner slabs are utilized for the similar imposed loads. The decreased section depths facilitate least building height together with consequent savings in facade costs. As a substitute, toward bigger buildings, it facilitates more floors to be developed inside the original building envelope.

Deflection Free Slabs: Unwanted deflections under service loads are virtually removed.

Water-resistant slabs: Post-tensioned slabs are designed to remain free from cracks and as a result water-resistant slabs should be formed with proper design, detailing and construction. The selection of concrete mix and curing method together with standard workmanship are also very important.

Early formwork stripping: The earlier stripping of formwork and curtailed backpropping requirements facilitate rapid construction cycles as well as fast reprocessing of formwork.

Materials Handling: The decreased material quantities in concrete and reinforcement significantly offer benefit to on-site carnage requirements. The stability of post-tensioning strand is roughly 4 times that of traditional reinforcement. So, the whole weight of reinforcing material is considerably minimized.

Column and footing design: The decreased floor dead loads are applied to create cost-effective design of the reinforcement concrete columns and footings. In multi-storied buildings, decreased column sizes may raise the floor net rentable area.




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Published By
Rajib Dey
www.constructioncost.co
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Post Tension Slab and its benefits

Generally, post-tensioned (PT) slabs belong to flat slabs, band beam and slabs or ribbed slabs. PT slabs provide the leaner slab type, as concrete functions to its strengths, mostly being maintained in compression. Longer spans are obtained because of pre-stress, which are also utilized to resist deflections.

Post-tensioned slabs employ high-strength tensioned steel strands to compress the slabs to retain most of the concrete in compression. Reinforcement is arranged to control the compression.

In Post tension slab, the cables/steel tendons are applied to replace the reinforcement. It develops a very well-organized structure to reduce material usages as well as economic span range with regard to reinforced concrete.

Post-tensioning is very useful to defeat the natural weakness of concrete in tension and to optimize its strength in compression. In concrete structures, high-tensile steel tendons/cables are placed in the element prior to casting.

If the concrete attains the preferred strength the special hydraulic jacks are used to drag tendons and retain them in tension with specially designed anchorages fixed at each end of the tendon. It offers compression at the edge of the structural member that enhances the strength of the concrete for withstanding tension stresses.

If tendons are properly curved to a specific profile, they will employ, besides compression at the perimeter, a beneficial upward set of forces (load balancing forces) that will resist applied loads, alleviating the structure from a portion of gravity effects.

In this type of slab, cables are attached in spite of reinforcement. In Steel reinforcement the gapping among bars is 4 inch to 6 inch while in Post tension slab the gapping is over 2m.

Benefits:

• It facilitates slabs and other structural members to be slimmer
• It facilitates us to develop slabs on expansive or soft soils
• The produced Cracks are retained firmly mutually
• Post tension slabs are useful for building up stronger structures economically.
• It minimizes or removes shrinkage cracking. So, no joints, or fewer joints, are essential
• It allows us to design longer spans in elevated members, like floors or beams

Drawbacks:
• Only experienced professionals can construct post tension slabs.
• If precaution is not undertaken at the time of making it, it can cause future mishaps. In various situations, untaught workers become unable fill the gaps of the tendons and wiring entirely. These gaps lead to decay of the wires which become breakable quickly and unexpected collapsing may occur.

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Published By
Rajib Dey
www.constructioncost.co
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