International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 06 | June -2017
p-ISSN: 2395-0072
www.irjet.net
Comparative Study of Post Tensioned and RCC Flat Slab in Multi-Storey Commercial Building Jnanesh Reddy R K1, Pradeep A R2 1PG
Student, Department of Civil Engineering, SSIT, Tumakuru-572105, Karnataka, India Professor, Department of Civil Engineering, SSIT, Tumakuru-572105, Karnataka, India ---------------------------------------------------------------------***--------------------------------------------------------------------2Assistant
Abstract - The post-tensioning method is now a day’s
The tensile strength of plain concrete is only a fraction of its compressive strength and the problem of it being deficient in tensile strength appears to have been the driving factor in the development of the composite material known as “Reinforced Concrete”.
increasing widely, due to its application. By using posttensioning method one can design the most economic and the safe design. While using this method more precautions has to be made for shear and deflection criteria for the slabs. The design of post-tensioned flat slab can be done by using load balancing and equivalent frame method. In a developing country like India the benefits of post stressing and particularly of Post-Tensioning are yet to be recognized. This has to be overlooked considering the significant benefits of Post- Tensioning can be advantageously procured. In the present study an attempt is made to compare the cost effectiveness of Post- Tensioned flat slab systems with respect to reinforced concrete flat slab system. Both the systems are analyzed using RAPT and ETABS respectively which is based on the design methodology. The results indicate that Post Tensioned flat slabs are cheaper than the RCC slab systems.
The development of early cracks in reinforced concrete due to incompatibility in the strains of steel and concrete was perhaps the starting point in the development of a new material like “post stressed concrete”. The application of permanent compressive stress to a material like concrete, which is strong in compression but weak in tension, increases the Apparent tensile strength of that material, because the subsequent application of tensile stress must first nullify the compressive post stress. Post stressing results more economical structures with avery high tensile strength instead of normal reinforcing steels.
Key words: Equivalent Frame Method, Load Balancing, Flat Slab, Post Tension, safe design, RCC.
1.
It offers larger spans and greater slenderness which results in reduced dead load. Thus, the load and size of the column and foundation reduce. Subsequently, the overall height of buildings reduces which enables additional floors to be incorporated in buildings of a given height.
INTRODUCTION
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 overall cost. In some countries, including the U.S., Australia, South Africa, Thailand and India, a great number of large buildings have been successfully constructed using posttensioned floors. Post stressed concrete has been used in seismic resistance building structure. Hence the structure will be safe from earthquake.
The use of unbounded tendons was first demonstrated by Dischinger in 1928, in the construction of a major bridge of the deep girder type, in which post stressing wires were placed inside the girder without any bond. Losses of post stress were compensated by the subsequent re-tensioning of the wires. Other advancements like development of vibration techniques for the production of high strength concrete and the invention of the doubleacting jack for stressing high tensile steel wires are considered to be the most significant contributions.
Post stressed concrete is basically concrete in which internal stresses of a suitable magnitude and distribution are introduced so that the stresses resulting from external loads are counteracted to a desired degree. In Reinforced Concrete members, the post stress is commonly introduced by tensioning the steel reinforcement.
It offers larger spans and greater slenderness which results in reduced dead load. Thus, the load and size of the column and foundation reduce. Subsequently, the overall height of buildings reduces which enables additional floors to be incorporated in buildings of a given height.
The earliest examples of wooden barrel construction by force fitting of metal bands and shrink fitting of metal tyres on wooden wheels indicate that the art of post stressing has been practiced from ancient times.
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