UPTU B. Tech.

(SEM. VI) EXAMINATION, 2006-07

CONCRETE STRUCTURE – II

Time : 3 Hours] [Total Marks : 100

Note : (1) Attempt all questions.

(2) Use of IS : 456 is allowed.

(3) Any data not given may be assumed suitably.

**1.**Attempt any two parts of the following : 10×2=20

(a) Compute the design moments of an interior panel of a flat slab of size 7 m x 5m. It is subjected to line load of 4.5 kN/m^{2} and floor finish of 1 kN/m^{2}.

(b) Design a circular roof slab of 4.2 m inside diameter fixed with edge beam of 230 mm wide. It has to carry a line load of 4 kN/m^{2}.

Use m-20 concrete and mild steel.

(c) What are various components of flat slab? Also discuss the deflection of flat slab.

**2.**Attempt any two parts of the following : 10×2 = 20

(a) A rectangular cross section of a curved beam is 300 mm x 500 mm. It is subjected to factored bending moment of 70 kN-M, factored torsional moment of 50 kN-M and factored shear force of 70 kN. Using M-20 grade concrete and fe-415 grade steel determine the reinforcement, for beam.

(b) A brick wall 300 mm thick carries a load of 170 kN/M length. Design a RCC footing, if the safe bearing capacity of soil is 100 kN/M^{2}. Use M-20 concrete and Fe-250 steel.

(a) Derive an expression for bending moment at any section of a semi circular beam which is supported on three equally spaced columns.

**1.**Attempt any two parts of the following : 10×2=20

(a) What are various elements of Intze water tank? Discuss the utility of braces in it.

(b) Design long wall of an under ground water tank 4 m x 10m x 3m deep. The soil consists of saturated unit weight of 17 kN/M^{3} and angle of repose of 30°. The water table is likely to rise upto ground level. Use M-20 concrete and HYSD bars.

(c) Design a cylindrical tank with flexible base for 200 KL. The depth of water is to be 2.8 m including a free board of 200 mm.

**2.**Design a cantilever retaining wall to retain 20×1=20 earth embankment 2.2 m high above ground level.

Its density is 16 kN/M^{3} and angle of repose 25°.

The earth is horizontal at top. The safe bearing capacity of soil is 105 kN/M^{2} and co-efficient of friction between soil and concrete is 0.5.

OR

**4.**Design a culvert of span 5.5 m over a drain for single lane and class B IRC loading. 65 mm thick wearing coat has to be provided over it, IRC loading has been given on the last page.**5.**A prestressed concrete I-Beam has its upper 20×1=20 flange 750 mm wide and 200 mm deep, lower flange 400 mm wide and 300 mm deep and a web of depth 500 and width 150 mm. It is supported over a span of 30 m and carries a u.d.l of 4 kN/M, exclusive of self weight. It is prestressed with 120 wires of 5 mm diameter, with their centroid 100 mm above the bottom edge and initially tensioned to 1000 N/mm^{2}. Assuming 15% losses in prestress determine the extreme fibre stresses at mid span (i) due to initial prestress and dead load (ii) due to final prestress, dead load and line load.OR

Describe various losses of prestress and their computation.