Check the safety of the designed pipe against 14 longitudinal stresses and bursting as per IS 78 4′ provisions. The strength of concrete at transfer is 50 N/mm2. Permissible longitudinal tensile stress is 0.8 fci. The maximum level to which they are stressed is 1000 N/mm2 at the time of prestress.
The possible losses in prestress can be expected to be 20% 5 mm φ and 7 mm φ high tension wires are available. A residual compression of 2 N/mm2 is expected to be maintained at service load. The maximum permissible compressive stress in concrete is 16 N/mm2 at transfer. The diameter of the pipe is 1200 mm and wall thickness of 100 mm. a) Briefly discuss the advantages of prestressed concrete pipes.ī) A prestressed concrete pipe is to be designed to withstand a liquid pressure of 2 N/mm2 internally. and minimum stresses are within the safe permissible limits of 14 N/mm2 in compression and 20 zero N/mm2 in tension.ģ. of cables required and arrange them suitably in the two principal directions and check if max. Prestressing cables consisting of four wires of 5 mm φ are initially stressed to 1200 N/mm2 are available for use. A simple flat slab 14 m × 10 m is supported by four columns so placed as to form a symmetrical rectangular grid 10 m × 8 m. Assume fck = 40 N/mm2 and fp =1600 N/mm2. Check for the safety of the slab against collapse. Calculate the horizontal spacing of the cables and their positions at the midspan section. The permissible compressive and tensile stresses in concrete at any stage not exceeding 15 N/mm 2 and zero N/mm2 respectively. Design anyone typical intermediate slab as a one way prestressed concrete slab with parallel posttensioned cables of 12#5 mm φ diameter initially stressed to 1200 N/mm2. The specified floor loading consists of a live load of 10 kN/m2 and a dead load (due to floor finish, partition etc.,) of 2.0 kN/m2 in addition to the self weight. For economy the span of the slab along 50 m is reduced by providing 4 equally spaced intermediate beams.
a) Discuss briefly different types of prestressed concrete floor slabs, with neat sketches.ī) The floor slab of an industrial structure covers an area of 25 m × 50 m. 3) Any missing data may be suitably assumed.
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(Civil) Degree Examination, January/February 2014 (2K8 Scheme) (Common to PSC/Str) PC – 201/SE – 206 : ADVANCED PRESTRESSED CONCRETE Time : 3 Hours
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