Design of Prestressed Concrete structures — Winter 2024

Explain the terms: (1) Pretensioning (2) Tendon (3) Anchorage

List the various types of tensioning device used in prestressed concrete.

Arectangular prestressed beam of 150 x 300 mm is used over an effective span of 10m. The cable is having with zero eccentricity at support and linearly varying to 50 mm at the center, carries a prestressing force of 500 kN. Find the magnitude of the concentrated load Qlocated at the center of the span, if the load counteracts the bending effect of the prestressing force.

Define (1) Bonded Prestressed Concrete (2) Post-tensioning (3) Degree of Prestressing.

Enlist the formula for calculating losses due to Elastic deformation and Friction in prestressed concrete sections

Explain with sketch IS 1343 recommendations for computing the Moment of resistance of rectangular section.

Enlist the advantages of composite construction with prestressed and in situ concrete for structural members.

Write the assumptions of Strain compatibility method.

Explain IS 1343 recommendations for design of prestressed members subjected to bending and torsion.

Aconcrete beam with a single overhang is simply supported at Aand B over a span of 8 m and overhang BC is 2 m. The beam is of size 300 x 900 mm and supports a UDL of live load of 3.52 kN/m over entire span in addition to self weight. Determine the profile of prestressing cable with effective force of 500 kN which can balance dead load and live load.

Enlist the differences of prestressed concrete over reinforced concrete.

Enlist different types of flexural failure and explain any one in detail.

Aconcrete beam is prestressed by a cable with initial prestressing force of 300 kN. The cross sectional area of wires in the cable is 300 mm2. Calculate the percentage loss of stress in the cable only due to shrinkage, if the beam is Pretensioned. Assume Es = 210 kN/mm2.1

Explain transmission length, and what is expression of it as per IS 1343 recommendations.

Explain the concept of thrust line in PSC sections

What is effective reinforcement ratio? In what way it influence the stress in tendons and the neutral axis depth at the limit state of collapse of prestressed concrete sections?

Explain IS 1343 recommendations for design of prestressed members subjected to shear.

Explain the concordant profile.

A Pretensioned prestressed concrete beam having a rectangular section of 150 x 350 mm has an effective cover of 50 mm. If fck = 40 MPa, fp = 1600 MPa and area of prestressing steel Ap = 461 mm2, Calculate ultimate flexural strength of section.

Enlist difference between time dependent and immediate losses in prestressed concrete sections.

Differentiate between web shear, flexural and flexure-shear cracks in concrete beam with sketches.

A Post tensioned prestressed concrete Tbeam having a flange width of 1200 mm and flange thickness of 200 mm, thickness of web being 300 mm is prestressed by 2000 mm2 at an effective depth of 1600 mm. If fck = 40 MPa, fp = 1600 MPa, Calculate ultimate flexural strength of unbounded T section assuming span/depth ratio as 20 and fpe = 1000 MPa.

Differentiate between Pre-tensioning and Post-tensioning.

What is non distortional prestressing?

Elaborate anchorage slip. How do you compute the loss of stress due to anchorage slip?