Question Paper: Limit state Method for Reinforced concrete stuctures Question Paper - Dec 16 - Civil Engineering (Semester 7) - Mumbai University (MU)

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## Limit state Method for Reinforced concrete stuctures - Dec 16

### Civil Engineering (Semester 7)

Total marks: 80

Total time: 3 Hours
INSTRUCTIONS

(1) Question No. 1 is compulsory

(2) Solve any three from remaining questions

(3) Draw neat diagrams wherever necessary

### Solve any question 4 Q1(a,b,c,d,e,f)

**1(a)**State four assumptions made in the Limit State of Collapse (flexure) in RCC. Also draw strain and stress diagram across the section.

**1(b)**What is the necessity of providing shear reinforcement? What are the various forms of shear reinforcement?

**1(c)**How can we increase the bond between steel and concrete?

**1(d)**Write any three points of differences between limit state method and Ultimate Load Design method in RCC.

**1(e)**What is combined footing? When is to be provided? What are the various types of combined footing?

**1(f)**What are the functions of providing distribution steel in slab?

**2(a)**Determine the ultimate moment of resistance for the beam having dimensions 300mm×550mm (effective), if it is provided with minimum tension steel reinforcement. Use LSM and material combinations are (i) M

_{25}concrete and Fe

_{415}steel.

ii) M

_{20}concrete and Fe

_{250}steel.

**2(b)**A beam of size 300×500 mm overall, is subjected to a factored bending moment of 320kNm. Compute the reinforcement required at an effective cover of 50 mm to compression and tension reinforcement. Use M25 concrete and Fe 415 steel.

d'/d | 0.05 | 0.100 | 0.15 | 0.20 |

f_{sc (MPa)} | 355 | 353 | 342 | 329 |

**3(a)**A reinforcement concrete beam of 300×550mm obverall is reinforcement with bars of 20 mm φ HYSD steel of grade Fe 500, placed at an effective cover of 50 mm. The beam carries a factored UDL of 150 kN/m over a simply supported clear span of 5m . Design the shear reinforcement if 2 bars are bent upward near support. Use M 25 concrete. Aslo sketch the shear reinforcement details, Width of the support may be taken as 300mm. Use the following design shear strength values for concrete.

pt% | 0.50 | 0.75 | 1.0 | 1.25 | 1.5 | 1.75 |

τ_{c} |
0.57 | 0.64 | 0.70 | 0.74 | 0.78 | 0.78 |

**3(b)**A top beam having 1150 mm effective width of flange has a thickness of flange equal to 100mm. The effective depth of the beam is 500 mm and width of the webis 300mm. It is reinforced with 2 bars of 25 mm φ and 4 bars of 20 mm φ on the tension side. Determine moment of resistance if M 25 concrete and Fe 415 steel is used for construction. Use LSM.

**4(a)**A hall of a residential building measures 4.25m×5.9m. It is supported by 300 mm thick wall on all four sides. Design the simply supported slab using M 20 and HYSD Fe 415 steel. Assume the live load on the slab as 4kN/m

^{2}and the floor finish load as 1kN/m

^{2}. Apply checks for shear, deflection and development length. Sketch the reinforcement details along both spans

Ly/Lx | 1.3 | 1.4 | 1.5 | 1.75 |

α_{x} |
0.093 | 0.099 | 0.104 | 0.113 |

α_{y} |
0.055 | 0.051 | 0.046 | 0.037 |

**4(b)**Design a Square RCC column to carry an axial service load 1800KN. It is 4m long, effectively held in position and restrained against rotation at both ends. Use M20 concrete, Fe415 steel and LSM.

**5(a)**Write step by procedure to design isolated footing subjected to axial load and uniaxial moment.

**5(b)**A rectangular beam of size 300×450 mm overall is reinforced with 4 bars of 20 mm φ as tension reinforcement . It is subjected to a service shear force of 40kN and a service bending moment of 30kNm. In addition to this it also carries a service torsional moment of 4kNm. Design the beam for combined LM,

SF and TM. Assume 50 mm as effective cover to the tension and compression reinforcement. Use M20 and Fe 415 as grades of the materials. Use LSM.

**5(c)**A RCC beam of size 300×550mm effective depth is reinforced with 5 bars of 16mm dia. In rension zone. Determine moment of resistance using Ultimate load method in RCC. Use M20 concrete and Fe 415 grade steel as the materials. Also Draw Stress block across the section.

**6**Design the combined footing for two columns CI of size 450×450 mm and C2 of size 600×20 600mm in size and carrying 600 KN and 900 KN as working loads respectively. The columns are spaced at 3.8 'n apart. The available width restriction is 2.5m. The face of the smaller column is 0.4m away from the property line. The SBC of the soil is 135kN/m

^{2}. Use M 25, Fe 415 and LSM. Sketch reinforcement details in longtutional transverse direction. Apply all necessary checks.