Analysis and Design of RCC and Post

Analysis and Design of RCC and Post-tensioned Flat Slabs Considering Seismic Effect ” As the floor system plays an important role in the overall cost of a building, a post-tensioned floor system is invented which reduces the time for the construction and finally the cost of the structure. In some countries, including the U.S., Australia, South Africa, Thailand and India, a great number of large buildings have been successfully constructed using post-tensioned floors. The reason for this lies in its decisive technical and economical advantages. According to Park.E.H.Kim et al [1] and Y. H. Luo, A. Durrani [2] the most important advantages offered by post-tensioning systems are as follows By comparison with reinforced concrete, a considerable saving in concrete and steel since, due to the working of the entire concrete cross-section more slender designs are possible. Smaller deflections compared to with steel and reinforced concrete structures. Good crack behavior and therefore permanent protection of the steel against corrosion. Almost unchanged serviceability even after considerable overload, since temporary cracks close again after the overload has disappeared. High fatigue strength, since the amplitude of the stress changes in the prestressing steel under alternating loads are quite small. If a significant part of the load is resisted by post-tensioning the non-prestressed reinforcement can be simplified and standardized to a large degree. Furthermore, material handling is reduced since the total tonnage of steel (non-prestressed + prestressed) and concrete is less than for a Reinforced Concrete floor. Assembling of precast elements by post-tensioning avoids complicated reinforcing bar connections with insitu closure pours, or welded steel connectors, and thus can significantly reduce erection time. Usually the permanent floor load is largely balanced by draped post-tensioning tendons so that only the weight of the wet concrete of the floor above induces flexural stresses. These are often of the same order as the design live load stresses. Post-tensioning usually balances most of the permanent loads thus significantly reducing deflections and tensile stresses. The P/A stress provided by post-tensioning may prevent tensile stresses causing the floor to crack. For the above reasons post-tensioned construction has also come to be used in many situations in buildings. In addition to the above mentioned general features of post-tensioned construction systems, the following advantages of post-tensioned slabs over reinforced concrete slabs are listed as follows: More economical structures resulting from the use of prestressing steels with a very high tensile strength instead of normal reinforcing steels. Larger spans and greater slenderness, which results in reduced dead load, which also has a beneficial effect upon the columns and foundations and reduces the overall height of buildings or enables additional floors to be incorporated in buildings of a given height.

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Analysis and Design of RCC and Post-tensioned Flat Slabs Considering Seismic Effect. "As the floor system plays an important. Role in the overall cost of, a building a post-tensioned floor system is invented which reduces the time for the construction. And finally the cost of the structure. In, some countries including the U.S, Australia South Africa, Thailand and India,,, A great number of large buildings have been successfully constructed using post-tensioned floors. The reason for this lies. In its decisive technical and economical advantages. According to Park.E.H.Kim et al [] and 1 Y. H. Luo A. Durrani 2, [] the. Most important advantages offered by post-tensioning systems are as follows By comparison with reinforced concrete a considerable,, Saving in concrete and, steel since due to the working of the entire concrete cross-section more slender designs are, possible. Smaller deflections compared to with steel and reinforced concrete structures. Good crack behavior and therefore permanent. Protection of the steel against corrosion. Almost unchanged serviceability even after considerable overload since temporary,, Cracks close again after the overload has disappeared. High, fatigue strength since the amplitude of the stress changes. In the prestressing steel under alternating loads are quite small. If a significant part of the load is resisted by post-tensioning. The non-prestressed reinforcement can be simplified and standardized to a large degree. Furthermore material handling, is. Reduced since the total tonnage of steel (non-prestressed + prestressed) and concrete is less than for a Reinforced Concrete. Floor. Assembling of precast elements by post-tensioning avoids complicated reinforcing bar connections with insitu closure. Pours or welded, steel connectors and thus, can significantly reduce erection time. Usually the permanent floor load is. Largely balanced by draped post-tensioning tendons so that only the weight of the wet concrete of the floor above induces. Flexural stresses. These are often of the same order as the design live load stresses. Post-tensioning usually balances. Most of the permanent loads thus significantly reducing deflections and tensile stresses. The P / A stress provided by post-tensioning. May prevent tensile stresses causing the floor to crack. For the above reasons post-tensioned construction has also come. To be used in many situations in buildings. In addition to the above mentioned general features of post-tensioned construction. Systems the following, advantages of post-tensioned slabs over reinforced concrete slabs are listed as follows: More economical. Structures resulting from the use of prestressing steels with a very high tensile strength instead of normal reinforcing. Steels. Larger spans and, greater slenderness which results in reduced, dead load which also has a beneficial effect upon. The columns and foundations and reduces the overall height of buildings or enables additional floors to be incorporated. In buildings of a given height.