STUDY AND EXECUTION OF POST TENSION SLABS ABSTRACT: Post-Tensioning is a method of reinforcing concrete, masonry and other structural elements. Post-Tensioning is a method of pre-stressing. Pre-stressed concrete or masonry has internal stresses (forces) induced into it during the construction phase for the purpose of counteracting the anticipated external loads that it will encounter during its lifecycle. Post-Tensioned reinforcing consists of very high strength steel strands or bars. Typically, strands are used in horizontal applications like foundations, slabs, beams, and bridges; and bars are used in vertical applications like walls and columns. A typical steel strand used for post-tensioning has a tensile strength of 1860 N/mm2. In comparison, a typical non-pre-stressed piece of reinforcing bar (rebar) normally has a tensile strength of about 600 N/mm2. In this project, we have seen and studied thoroughly some works on the site related to post tensioned slabs. The various sizes of tendons available, which are the materials imparting prestress to the structure were studied thoroughly. We have also understood and performed building column line staking on site. We have visited the site and taken part in the execution work under the structural engineer in-charge. The unbonded tendons are typically prefabricated at a plant and delivered to the construction site, ready to install. The tendons are laid out in the forms in accordance with installation drawings that indicate how they are to be spaced, what their profile (height above the form) should be and where they are to be stressed. After the concrete is placed( from the RMC trucks) and has reached its required strength, usually about 75% of its final strength, then the prestressing process begins. The concrete grade that was used was M35 and hence, after 7 days when it achieved the strength of 25 N/mm2, prestressing was achieved through Prestressing powerpack using a mono strand stressing jack. The principle is that when the tendons are stretched, want to return to their original length but are prevented from doing so by the anchorages.
STUDY AND EXECUTION OF POST TENSION SLABS ABSTRACT: Post-Tensioning is a method of reinforcing concrete, masonry and other structural elements. Post-Tensioning is a method of pre-stressing. Pre-stressed concrete or masonry has internal stresses (forces) induced into it during the construction phase for the purpose of counteracting the anticipated external loads that it will encounter during its lifecycle. Post-Tensioned reinforcing consists of very high strength steel strands or bars. Typically, strands are used in horizontal applications like foundations, slabs, beams, and bridges; and bars are used in vertical applications like walls and columns. A typical steel strand used for post-tensioning has a tensile strength of 1860 N/mm2. In comparison, a typical non-pre-stressed piece of reinforcing bar (rebar) normally has a tensile strength of about 600 N/mm2. In this project, we have seen and studied thoroughly some works on the site related to post tensioned slabs. The various sizes of tendons available, which are the materials imparting prestress to the structure were studied thoroughly. We have also understood and performed building column line staking on site. We have visited the site and taken part in the execution work under the structural engineer in-charge. The unbonded tendons are typically prefabricated at a plant and delivered to the construction site, ready to install. The tendons are laid out in the forms in accordance with installation drawings that indicate how they are to be spaced, what their profile (height above the form) should be and where they are to be stressed. After the concrete is placed( from the RMC trucks) and has reached its required strength, usually about 75% of its final strength, then the prestressing process begins. The concrete grade that was used was M35 and hence, after 7 days when it achieved the strength of 25 N/mm2, prestressing was achieved through Prestressing powerpack using a mono strand stressing jack. The principle is that when the tendons are stretched, want to return to their original length but are prevented from doing so by the anchorages.
24.Detailed%20study%20and%20execution%20of%20post%20tension%20slabs.docx