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R.C.C.STRUCTURE

UNIT I

1. State the drawbacks and limitations of working stress method.

2. What do you understand by balanced, under reinforced and over reinforced

section? Explain with the help of stress diagram.3. Determine moment of resistance of a singly reinforced beam 160 mm wide and

300 mm deep to the centre of reinforcement, if the stresses in steel and concrete

are not to exceed 140 Mpa and 5 Mpa. Total area of steel provided is 8.04 cm 2

.If the beam is used over an effective span of 5 m find the maximum load the

beam can carry, inclusive of self weight. Take m=18. Use working stress

method.

4. A reinforced concrete beam of rectangular section 300 mm wide by 650 mmdeep is reinforced with 4 bars of 32 mm diameter at an effective depth of 600

mm using M20 grade concrete and Fe 415 HYSD bars, estimate the moment of

resistance of the section.

5. Explain various systems for prestressing and enlist the losses in prestressing.6. A prestressed concrete beam 300 mm wide and 450 mm deep is prestessesed

with steel wire of cross sectional area 250 mm2 located at constant eccentricityof 50 mm carrying an initial stress of 1100 N/ mm2 The span of the beam is

12m. calculate the percentage loss of stress in wire if the beam is pretensioned

and the beam is post tensioned using following data:- Es=200 KN/mm 2, Ec = 40

KN/ mm2 Relaxation of steel stresses = 5 % of initial stress, shrinkage ofconcrete = 300 x 10 -6 units for post tensioning. Creep coefficient = 1.5, slip at

anchorage = 1.5 mm, friction coefficient for wave effect= 0.0010 per m.

7. A prestressed concrete composite beam centr to centr spacing of beams is 2metres. Youngs Modulus of concrete for prestressed concrete is 0.3x105 N/

mm

2

and the modular ratio of Youngs modulus of concrete for the cast in situconcrete and prestressed concrete is 0.8. The shrinkage is 1.5 x 105-4 mm/mm.Determine the shrinkage stresses at the top and bottom of slab and at top and

bottom of I- beam.

8. Explain with the help of neat sketches following prestressing systems:i) Freyssinet system

ii) Magnel-Blaton system

iii) Gifford Udall system

UNIT II

9. Define characteristic load & partial safety factors.

10. State the modes of failure of a R.C. member in flexure.11. Formulate from fundamental the expression for depth for critical neutral

axis(nd).Lever arm(jd) and moment of resistance (Q) for balanced rectangular

singly reinforced section.12. A reinforced concrete rectangular beam of overall dimensions 250 mm x

600mm is reinforced with 4x20 mm bars in tension at an effective cover of

40 mm. The beam supports a brick wall 250 mm which and H high over a

simply supported span of 4.5 m. Calculate the height H of wall the beam can

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support. Assume density of brick masonry as 20 KN/m3. Use M20 concrete and

Fe415 steel.

13. A reinforced concrete beam is to be designed over an effective span of 5m tosupport a design service load of 8 KN/m. Adopt M-20 grade concrete and Fe415

HYSD bars and design the beam to satisfy the collapse and serviceability limit

states.14. Determine the area of reinforcement required for a singly reinforced concrete

section having a breadth of 300 mm and an effective depth of 600 mm to resist a

factored moment of 200 KNm. Adopt fck = 20 N/ mm2 and fy = 415 N/ mm2 .15. Determine the minimum effective depth required and te corresponding area of

tension reinforcement for a rectangular beam having a width of 200 mm to resist

an ultimate moment of 200 KNm. Using fck = 20 N/ mm 2 and fy = 415 N/ mm2

.16. Explain the limit state of collapse.

UNIT III

17. Calculate moment of resistance of T section shown in fig. Grade of concrete =M20,Grade of steel = Fe415.Width of flange = 1500 mm, Depth of flange =

100mmDepth of beam = 600 mm, Width of rib = 300 mm, Area of tensionreinforcement is 3473 mm2. Take effective cover = 65 mm

18. Calculate the moment of resistance of an isolated T beam of following

properties; i)width of flange= 2500 mm ii)simply supported span= 6M iii)

thickness of flange = 150 mm iv) depth of rib = 350 mm v) width of rib = 230mm vi) Area of tension steel = 4 NOs. of 16 mm dia. Fe415 vii) effective

cover= 50 mm viii) use M20 grade of concrete. Calculate area of steel for

balanced section.19. A tee beam has an effective flange width of 2500 mm and depth of flange is 150

mm, width pf rib is 300 mm, effective depth is 800 mm. Using M20 grade

concrete and Fe 415 HYSD bars, estimate the area of tension reinforcementrequired if te section has to resist a design ultimate moment of 1200 KNm.

20. Design axially loaded circular column with M20 grade and Fe415. Design the

helical rings. Axial load on column = 1000KN. Assume diameter of column=350 mm.

21. A R.C.C. square column of 3.5 m effective length is required to resist an axial

load of 1750 KN. Design column using M20 grade of concrete and Fe415 grade

of steel. Assume that unsupported length and effective length are equal.22. Design the reinforcement in a spirally tied column of 400 mm diameter,

supporting an axial factored load of 1500 KN. The column has an unsupported

length of 3.4 m and is braced against side sway. Adopt M25 and Fe 415.23. Design the reinforcement in a short column 400 mm by 600 mm subjected to an

ultimate axial load of 1600 KN together with an ultimate moments of 120 KNm

and 90 KNm about the major and minor axis resp. Adopt M25 and Fe 415.

UNIT IV

24. Design shear reinforcement for a beam with b=350 mm, d= 550 mm. Ultimate

shear force = 125 KN. Percentage of steel is 1.67 percent. Use M25 mix concrete

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and Fe415 steel.

25. Explain limit state of serviceability.

26. Explain development length.27. Write notes on deflection control of beam and one way slab.

28. A reinforced concrete beam has a support section with a width of 250 mm and

effective depth of 500 mm. The support section is reinforced with 3 bars of 20mm diameter on the tension side 8 mm diameter 2 legged stirrups are provided

at a spacing of 200 mm centers. Using M20 grade concrete and Fe 415 HYSD.

Calculate the shear strength of the support section.29. Design the development length for steel in above section.

30. Explain cracking in structural member.

31. Explain short term deflection and long term deflaction.

UNIT V

32. A rectangular R.C.C. tank is required to store 10,000 liters of water. Depth of

water in the tank= 3m. Free board = 0.2 m. Adopt M20 concrete and Fe415

HYSD bars. Tensile stresses in steel limited to 100 N/ mm

2

at water face and125 N/ mm2 away from water face. Sketch the details of reinforcement in the

walls of the tank.Use Approximate method for calculation of wall thickness.33. Design a circular water tank resting on firm ground. The capacity of tank is 300

m3 The depth of water is 2.5 m. Take free board of 0.5 m. Design 1) The wall of

tank 2) Top dome 3) Top ring beam at the junction of wall and dome. Use M20

concrete and Fe 415 steel. Show reinforcement details.34. A rectangular R.C.C. tank is required to store 12,000 liters of water. Depth of

water in the tank= 3m. Free board = 0.2 m. Adopt M20 concrete and Fe415

HYSD bars. Tensile stresses in steel limited to 100 N/ mm2 at water face and125 N/ mm2 away from water face. Sketch the details of reinforcement in the

walls of the tank.Use IS code method for calculation of wall thickness.

35. A pretensioned beam of rectangular section 80 mm wide and 120 mm deep I tobe designed to support concentrated loads of 4 KN each at one third span points

over an effective span of 3m. The permissible stresses in concrete are limited to

zero and 1.4 N/ mm2 tension at transfer and working load resp. If 3 mmdiameter wires initially stressed to 1400 N/ mm2 are used find the number of

wires required and the eccentricity of the prestressing force assuming 20 % loss

in prestress. Take weight of concrete= 24 KN/m3

36. A presstressed concrete rectangular beam 30 mm x 600mm is presstressed witha force 1565 KN applied at 180 mm from the bottom the force finally reducing

to 1361 KN. The span of beam is 12.2 m and carries two equal live loads 45 KN

each at a distance of 4.6 m from each support. Find the extreme fiber stresses atthe mid- span under i) initial prestress and no live load and final conditions.

Assume specific weight of concrete = 24 KN/m3

37. A prestressed concrete T beam is to be designed to support an imposed load of 4KN/m over an effective span of 5 m. The flange is 400 mm wide and 40 mm

thick, rib is 100 mm wide and 200 mm deep. Yhe stress in concrete must not

exceed 15 N/ mm2 in compression and zero in tension at any stage. Check for

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the adequacy of the section provided and calculate the minimum prestressing

force necessary and corresponding eccentricity.

UNIT VI

38. Design a R.C. square pad footing for a column of section 400 mm x 400 mmsubjected to a load of 1200 KN at service state. Take safe bearing capacity of

soil = 150 KN/ m2 ,Wt of soil = 20 KN/m3 . Take depth of footing below ground

level = 2m. Use M20 grade concrete and Fe415 grade steel. Draw reinforcementdetails.

39. A hall of effective dimensions 8mx15m is provided with beams at 3 m c/c

forming five slab panels each of 3mx8m(effective). Design the slab panels as

continuous slab using limit state method for following data:- 1) Live load 4KN/m2 2) Finishing load 1 KN/m2 3) M20 concrete and Fe415 steel. Provide all

checks and sketch the reinforcement details.

40. Design a rectangular pad footing for a column of section 300 mm x 450 mm

subjected to an axial load of 1000 KN at working conditions. Assume the SBCof soil as 200 KN/ m2. Use M20 concrete and Fe415 steel. Draw neat sketch of

reinforcement details.41. Design a one way slab with a clear span of 3.5 m, simply supported on 200 mm

thick concrete masonry walls to support a live load of 4 KN/ m2 . Adopt M20

grade and Fe415 HYSD bars.

42. Design a cantilever chajja slab projecting 1m from the support using M20 gradeconcrete and Fe415 HYSD bars. Adopt a live load of 3 KN/ m2

43. Design a dog legged stair case (waist slab type) for an office building assuming

floor to floor height of 3m. Width of flight = 1.2 m, landing width = 1.2 m.Adopt a tread of 300 mm and rise of 150mm. Use M20 grade concrete and

Fe415 HYSD bars. Live load 5KN/ m2 . Assume the landing to be supported

only on two edges perpendicular to the risers.44. Design open well type stair case for a multi storey office complex using the

following data. Length of each flight = 1.5 m (5 tread in each flight), Length of

landings= 1m, Tread = 300 mm and riser = 150 mm, The landings are supportedall round on 300 mm masonry walls. Live load = 5 KN/ m2. fck= 20 N/mm2 ,

fy=415 N/mm2

45. Design a singly reinforced concrete beam to suit the following data.

Clear span = 4mWidth of supports = 300 mm

Service load = 5 KN/m

Use M20 & Fe415