## Design and Drawing of Reinforced Concrete Structures - May 2017

### MU Civil Engineering (Semester 8)

Total marks: --

Total time: --
INSTRUCTIONS

(1) Assume appropriate data and state your reasons

(2) Marks are given to the right of every question

(3) Draw neat diagrams wherever necessary
**1(a)** Draw neat sketches, showing the behaviour of vertical stem wall & heel slab of a counterfort retaining wall. What is the reason of providing vertical ties & horiziontal ties in the counterfort part?
4 marks

**1(b)** What are the various situations demanding the need of raff Foundation? What are the advantages or Raft Foundation?
4 marks

**1(c)** Fig.1. shows a part plan of the building, slab (S1) has thickness of 120 mm & slab (S2) has thickness of 140mm. For the building live load = 4kN/m^{2}, floor finish = 1kN/m^{2}. Beam B1 is 8.2 m long, 200 mm wide & 450 mm deep. Also beam B1 carries a masonry wall 115 mm thick & 3 m high, with masonry unit wt= 18kN/m^{3}. Calculate the factored (design) UDL carried by the beam ( B1). Include the self weight of the beam itself.

!mage
4 marks

**1(d)** Write a note on Open Well Staircase, with a neat sektch.
4 marks

**1(e)** A rectangular underground water tank has wall height of 3 m. The tank is empty. The soil outside is saturated, with the saturated unit weight = 18kN/m^{3}. Unit weight of water = 9.81kN/m^{3}. Angle of repose of soil = 30°, determine the pressure at the base of wall.
4 marks

**2** Carry out the design for the slab S2 & beam B2(fig.2). Take Live Load = 3kN/m^{2}, Floor Finish = 1.5kN/m^{2}. Use M20 grade of concrte & Fe415 grade steel. Take all the necessary checks. Draw neat reinforcement diagram. Use Limit State Method.

!mage
4 marks

**3** Carry out the complete design of a catilever retaining wall to retain the leveled back-fill, 5.2m above the ground level. Unit weight of the soil is 17 kN/m^{2} & its angle of repose is 30°, Safe Bearing Capacity of the foundation soil us 220 kN/m^{2}. The coefficient of friction between the soil & concrete at the base is 0.60. Use M20 grade of concrete & Fe415 steel. Carry out all the necessary stability checks. Draw a neat sketch, indicating the reinforcement details. Adopt Limit State Method.
4 marks

**4(a)** Design a dog-legged staircase for an office building in a room which measures 3m×6m (clear dimensions of inside dimensions) Floor to Floor height is 3.5m. The building is liable to over- crowding, as it's a public building. Stairs are supported on brick wall 230 mm thick at the ends of the landings( i.e. landing spans parallel to the stairs) Provide M20 concrete & Fe415 steel. Fixing the dimensions of risers & treads for the human comfort, is expected. Carry out the necessary checks. Show the reinforcement detail. Use Limit State Method.
4 marks

**5(a)** Design a circular water tank of 13m internal diameter & 5m height. The tank has flexible base & it rests on the ground. Use M30 concrete & Fe415 steel. Use Working Stress approach. The permissible stress in steel under direct tension is 1.5MPa. The following table can be referred to fix the thickness of the tank wall or, alternate approaches can be adopted. Draw reinforcement details. Use Working Stress apporach. Table; Minimum Thickness of Members in Direct Tension ( Uncracked Condition).

Grade of Concrete | Thickness of members in (mm) for tension T in (Newton) | |

Mild Steel | HYSD Bars | |

M25 | T/1465 | T/1444 |

M30 | T/1682 | T/1660 |

**5(b)** Design a rectangular water tank, open at the top. The clear size to be provided is (3m×8m) & 3m deep. The tank rests on a firm ground. Provide M25 grade concrete & Fe415 steel Take 6_{abc}= 8.5MPa & permissible stress in steel= 150 Mpa. Use approximate method for the analysis. Adopt Working Stress apporach. Draw steel details.
4 marks

**6(a)** A hall in a building has a floor consisting of One-Way Continuous Slab cast with Simply Supported beams of width 250mm, spaced at 4 m c/c (fig.3) The clear span of the beam is 9m. Assuming a Live Load on the slab as 3kN/m^{2}, partition load as 1 kN/m^{2} & load due to finishes of 0.6kN/m^{2}, design the slab with M20 grade concrete & Fe415 steel. Draw reinforcement details. Adopt Limit State aporach.

!mage
4 marks

**6(b)** Design a suitable raft slab connecting the columns of a building (fig.4). Design of the continuous beam over the raft slab is not needed. The size of the building (12m×12m), with the columns spaced at 4m intervals. Service load transmitted by eac column is 450 kN, column size is (300mm×300mm). Soil SBC is 120MPa. Use M20 grade concrete & Fe 415 steel. Adopt Limit State Method.

!mage.
4 marks