MATERIALS: High strength concrete and steel, Stress-Strain characteristicsand properties.2 HoursBASIC PRINCIPLES OF PRESTRESSING: Fundamentals, Loadbalancing concept, Stress concept, centre of Thrust. Pre-tensioning and post-tensioning systems, tensioning methods and end anchorages.
Stresses in concrete due topre-stress and loads, stresses in steel due to loads, Cable profiles.
Various losses encountered in pre-tensioningand post tensioning methods, determination of jacking force.
Deflection of a pre-stressed member – Short term andlong term deflections, Elastic deflections under transfer loads and due todifferent cable profiles. Deflection limits as per IS 1343. Effect of creep ondeflection, load verses deflection curve, methods of reducing deflection
Flexure -IS Code recommendations –Ultimate flexural strength of sections.
Shear - IS Coderecommendations, shear resistance of sections, shear reinforcement. Limitstate of serviceability – control of deflections and cracking.
Transmission of prestress in pretensionedmembers, transmission length, Anchorage stress in post-tensioned members.Bearing stress and bursting tensile force-stresses in end blocks-Methods, I.S.Code, provision for the design of end block reinforcement.
Design of pre-tensioned and post-tensionedsymmetrical and asymmetrical sections. Permissible stress, design ofprestressing force and eccentricity, limiting zone of pre-stressing force cableprofile