Name of the College : Valliammai Engineering College
Subject : Prestressed Concrete Structures
Website : valliammai.co.in
Document Type : Question Bank
Department : Civil Engineering
Semester : 7
Degree : B.E
Question Bank : https://www.pdfquestion.in/uploads/valliammai.co.in/1714-Prestressed%20Concrete%20Structures.pdf
Valliammai Prestressed Concrete Structures Question Paper
Unit-1
INTRODUCTION – THEORY AND BEHAVIOUR
1. Define prestressed concrete.
2. What are the advantages of PSC construction
3. Define Pre tensioning and Post tensioning
Related : Valliammai Engineering College CE2401 Design of Reinforced Concrete and Brick Masonry B.E Question Bank : www.pdfquestion.in/1703.html
4. What is the need for the use of high strength concrete and tensile steel in prestressed Concrete?
5. Define Kern Distance.
6. What is Relaxation of steel?
7. What is concordant prestressing?
8. Define bonded and unbondedprestressing concrete.
9. Define Axial prestressing
10. List the losses of prestress
11. What are the various methods of prestressing the concrete?
12. Enumerate load balancing concept
13. What are the sources of prestress?
14. Differentiate full prestressing and partial prestressing.
15. What is the permissible limit for shrinkage of concrete in pretensioned and post tensioned members as per IS code?
16. State any two advantages of prestressed concrete over reinforced concrete?
17. What are the advantages of pretensioned concrete over post tensioned concrete?
18. What are the grades of concrete to be used in pre tensioned and post tensioned works?
19. What is meant by pressure line?
20. Why loss due shrinkage is more for pretensioned member compared to post tensioned member?
16marks
1. A rectangular concrete beam 100mm wide & 250mm deep spanning over 8m is prestressed by a straight cable carrying a effective prestressing force of 250kN located at an eccentricity of 40mm. The beam supports a live load of 1.2 kN/m.
a) Calculate the resultant stress distribution for the centre of the span cross section of the beam assuming the density of concrete as 24kN/m2
b) Find the magnitude of prestressing force with an eccentricity of 40mm which can balance the stresses due to dead load & live load at the soffit of the centre span section
2. A PSC beam of 120mm wide and 300mm deep is used over an span of 6m to support a udl of 4kN/m including its self weight. The beam is prestressed by a straight cable carrying a force of 180kN & located at an eccentricity of 50mm. Determine the location of the thrust line in beam & plot its position at quarter & central span sections.
3. A Prestressedpretensioned beam of 200mm wide and 300mm deep is used over an span of 10m is prestressed with a wires of area 300mm2 at an eccentricity of 60mm carrying a prestress of 1200 N/mm2 Find the percentage of loss of stress, Ec= 35 kN/mm2 Shrinkage of concrete = 300 x 10-6 , creep coefficient =1.6
4. A PSC beam of 120mm wide and 300mm deep is used over an span of 6m is prestressed by a straight cable carrying a force of 200 kN & located at an eccentricity of 50mm. Ec= 38 kN/mm2 . Find the deflection at centre span
a) Under prestress + self weight
b) Find the magnitude of live load udl which will nullifythe deflection due to prestress & self weight.
5. A PSC beam of 230mm wide and 450mm deep is used over an span of 4m is prestressed by a cable carrying a force of 650kN & located at an eccentricity of 75mm. The beam supports three concentrated loads of 25kN at each quarter span points. Determine the location of the pressure line in beam at centre, quarter & support sections. Neglect the moment due to self weight of the beam.
6. A PSC beam with rectangular section, 150mm wide 300mm deep is prestressed by three cables each carrying a effective prestress of 200kN. The span of the beam is 12m. The first cable is parabolic with an eccentricity of 50mm below the centroidal axis at the centre of the span and 50mm above the centroidal axis at the supports.The second cable is parabolic with an eccentricity of 50mm at the centre of the span and zero eccentricity at the supports. The third cable is straight with an eccentricity of 50mm below the centroidal axis.If the beam supports an UDL of 6kN/m and Ec=38kN/mm2 Estimate the instantaneous deflection for the following stages
i) Prestress + self weight of the b
ii) Prestress + self weight of the beam + live load
7. (i) Explain why high strength concrete and high strength steel are needed for PSC construction
(ii) State different types of prestressing
8. (i) Explain shrinkage of concrete in PSC members
(ii) Explain durability, fire resistance and cover requirements for PSC members
9. A PSC beam supports an imposed load of 5kN/mm2 over a simply supported span of 10m.The beam has an I section with an overall depth of 450mm.Thickness of flange and web are 75mm and 1000mm respectively. The flange width is 230mm. the beam is prestressed with an effective prestressing force of 350kN at a suitable eccentricity such that the resultant stress at the soffit of the beam at mid span is zero. Find the eccentricity required for the force.
10. A PSC beam of section 120mm wide and 300mm deep is used over an effective span of 6m to support an udl of 4kN/m including self weight. The beam is prestressed by a straight cable with a force of 180kN and located at an eccentricity of 50mm. Determine the location of thrust line in the beam and plot its position.
UNIT -2
DESIGN CONCEPTS
1. Mention the functions of end block
2. What are the stages to be considered in the design of prestressed concrete section under flexure?
3. What is the zone of transmission in the end block of prestressed concrete structures?
4. What are the types of flexural failure encountered in prestressed concrete member?
5. How do you compute the ultimate flexural strength of section with tensioned and untensioned reinforcement in tension zone of concrete sections?
6. Explain with neat sketches the IS1343 code method of computing the moment of resistance of rectangular section.
7. What is strain compatibility method?
8. How will you improve the shear resistance of concrete beam using prestressing techniques?
9. Define anchorage zone
10. Sketch the pattern of reinforcement in anchorage zone.
11. What are the methods of stress analysis in anchorage zone?
12. Write the assumptions in strain compatibility method of prestressed concrete sections
13. List the applications of partial prestressing.
14. What is meant by partial prestressing?
15. What is meant by end block in a post tensioned member?
16. Compare the flexure failure of conventional RC beam with PSC beam
17. What is effective reinforcement ratio?
18. What are the code provisions for bond and transmission length?
19. Define Bursting tension
20. Define degree of prestressing.