Post Tensioned Mat Foundation

The majority of post tensioned foundation plans will show every strand across the slab a callout for its length a color code for identification and the expected elongation from a successful stress.

Post tensioned mat foundation.

The first edition of the post tensioning manual was published in 1972 and as of the time of this writing 2018 they are up to their 6th edition. A post tension slab is a concrete slab or foundation that contains high tension cables running through the concrete to increase strength and reduce cracking typically in areas with poor soil conditions. Post tensioned concrete in building construction post tensioned foundations 1. Introduction while the use of prestressing in superstructures is well established foundations have only rarely been prestressed.

A residential post tensioned concrete slab will typically be 8 inches thick and use 3000 psi concrete. The post tensioning institute designed post tensioned foundations. A raft foundation is often used when the soil is weak as it distributes the weight of the building over the entire area of the building and not over smaller zones like individual footings or at individual points like pile foundations this reduces the stress on the soil. A waffle slab foundation also called a ribbed slab foundation is an above ground type of foundation used to provide load bearing capacity in expansive rocky or hydro collapsible soils.

I only managed to find some practical approaches on a book by dirk bondy. The foundation is created by placing a series of single use plastic forms set directly on grade to create a grid of ribs and then monolithically pouring a post tensioned rebar or fiber reinforced concrete. I am trying to gather as much information as i can inorder to enhance my understanding on the design of post tensioned mat foundation which am facing. The concept of stress is very basic to civil engineering.

Once the concrete has gained strength to 2000 psi typically within the 3 to 10 days recommended by pti the tendons are stressed. Apart from certain technical considerations this may be due to some conservatism inherent in foundation engineering. Post tensioned mat foundation design post tensioned mat foundation design efr civil environmental op 9 may 20 07 57.