Question Paper: Limit state Method for Reinforced concrete stuctures Question Paper - May 17 - Civil Engineering (Semester 7) - Mumbai University (MU)

0

## Limit state Method for Reinforced concrete stuctures - May 17

### Civil Engineering (Semester 7)

Total marks: 80

Total time: 3 Hours
INSTRUCTIONS

(1) Question No. 1 is compulsory

(2) Answer any three from the remaining

(3) Draw neat diagrams wherever necessary

**1(a)**Distinguish between One Way Slab & Two Way Slab.

**1(b)**A beam (300 mm x 600 mm) is reinforced with 2 bars of 25 mm diameter. Find the Ultimate Moment of Resistance. Use Ultimate Load Theory. Use M20/Fe415. Assure the effective cover = 37.5 mm

**1(c)**Discuss characteristic load & characteristic strength of materials.

**1(d)**Explain the Types of Shear Reinforcement. Draw neat sketches.

**1(e)**Write a note on design of columns subjected to Compression & Uniaxial Bending.

**2(a)**A rectangular beam, having 200 mm width & 400 mm effective depth, is reinforced with 3 bars of 16 mm diameter Fe415 steel. Find the ultimate (factor or design UDL) which the beam can safely carry over a span of 5m. Use M20 concrete.

**2(b)**A simply supported rectangular beam of 8m clear span carries a factored load of 45kN/m over the entire span. The beam is 230 mm wide & effective depth is 500 mm. It is reinforced with 6 bars of 20 mm diameter bars. Design the shear reinforcement using vertical stirrups only. The ends of the beam are not confined by the compressive reaction. Use M20 concrete & Fe415 steel. Sketch the details.

**2(c)**In a RCC member, the best way to censure adequate bond is to :

- (i) Provide minimum number of large dia bars
- (ii) Provide large number of smaller dia
- (iii) Increase the cover for reinforcement
- (iv) Provide additional stirrups

**3(a)**A rectangular beam of size 30 mm width & 500 mm effective depth is subjected to a factored moment of 200 kNm. Find the reinforcement for flexure. Use M20 concrete & Fe415 steel.

**3(b)**Find the Limiting Moment of Resistance & Limiting Area of Steel for a T-beam, having flange width of 1600 mm, effective depth of 350 mm & flange thickness of 100 mm. The web width is 250 mm. Use M20 concrete & Fe500 steel.

**3(c)**In Limit State Design of RCC, deflection is computed by using

- (i) Initial tangent modulus
- (ii) Secant modulus
- (iii) Tangent modulus
- (iv) Short term & long term values of-young's modulus

**4(a)**Design a short square column to cany a safe axial load of 1600kN. It is 4m long, effectively held in position & restrained against rotation at both ends (effective length 0.65L). Use M20 concrete & Fe415 steel. Show the steel details on sketches. Cany out the check for minimum eccentricity.

**4(b)**A simply supported one-way slab of a public building has a clear span of2.5 m & is supported on 9 beams 230 mm wide. Design the slab if Live Load is 5 kN/m. Use M20 concrete & Fe415 steel. Show reinforcement details. Cany out check for shear. Other checks are not needed.

**4(c)**In Limit State Design of Concrete Structures, strain distribution is assumed to be:

- (i) Linear
- (ii) Non-linear
- (iii) Parabolic
- (iv) Parabolic & rectangular

**5(a)**A rectangular beam section is (300 mm x 600 mm) overall. Concrete is M20 & steel is Fe415. Factored moment is 116 kNm, factored torsion is 46kNm & factored shear is 95kN. Find the reinforcement required. Sketch the details.

**5(b)**Design a slab for a room of a building, whose clear dimensions are (4 m x 5 m)' is supported on walls of width 300 mm. The Live Load = 4 kN/m2 & Floor Finish = 1 kN/m2. Use M20 Concrete & Fe415 steel. Corners of the slab are not held down. Sketch reinforcement details. Serviceability checks are not needed

**5(c)**Limit State of Serviceability for deflection including the effects due to creep shrinkage & temperature occurring alter erection of partitions & application of finishes as applicable to floors & roofs, is restricted to. (i) Span/150 (ii) Span/200 (iii) Span/250 (iv) Span/350

**6(a)**Design a square footing of uniform thickness for an axially added column of (450mm x 450 mm) size. The SBC of soil= 190kN/m2 Column carries a load of Use M20 concrete & Fe415 steel. Sketch the steel details.

**6(b)**Draw the laboratory Stress-Strain curves & Idealized Stress Strain curves (asperIS456:2000) for the Concrete & the steel. Explain the same.

Table: Design Shear Strength of Concrete

100 A/bd | $\le$ 0.15 | 0.25 | 0.50 | 0.75 | 1.00 | 1.25 | 1.50 | 1.75 | 2.00 | 2.25 | 2.5 & above |
---|---|---|---|---|---|---|---|---|---|---|---|

$\tau_c$ (MPa) for M20 concrete | 0.28 | 0.36 | 0.48 | 0.56 | 0.62 | 0.67 | 0.72 | 0.75 | 0.79 | 0.81 | 0.82 |

Table: Values of (k) for Solid Slab

Overall Slab Depth (mm) | $\ge$ 300 | 275 | 250 | 225 | 200 | 175 | $\le$ 150 |
---|---|---|---|---|---|---|---|

(k) | 1.00 | 1.05 | 1.10 | 1.15 | 1.20 | 1.25 | 1.30 |

Table: Stress in compression steel, fsc(MPa) in Doubly Reinforced Beams

fy(MPa) | (d'/d) | - | - | - |
---|---|---|---|---|

- | 0.05 | 0.1 | 0.15 | 0.20 |

415 | 355 | 353 | 342 | 329 |

Table: Bending Moment Coefficients for Slabs Spanning in 2 Directions at Right Angles, Simply Supported on Four Sides