IB..JGT-K..DJA
CIVIL ENGINEERING
Paper I

.Time Allowed TAree Hours 1 IMaximum Marks: 2001
INSTRUCTIONS
Candidates should aUempt questions 1 and. 5
which are compulsory,. and any THREE ofthe


remaining questions, selecting at least ONE
question from each Section.
ASSUlne suitable data, ifconsidered 'necessary,
and indicate the. same clearly.
.­

Standard notations are given in the questions
and these notations have their usual meanings;
unless otherwise indicated.

All questions have equal marks.
Marks allotted to each part/subpart of a
question are indicated against each.

Answers must be written in ENGLISH only.
B-JGT-K-DJA 1 [Contd.]
SECTION A

1. Attempt any four of the following: 10x4=40
Form Lame's equations for a thick cylinder having internal radius and external radius subjected to internal pressure Po. What is the equation for shear stress at any radius r 5
(ii)State and explain forced vortex as occurring in acentrifugal pump. 5

Parallel chord truss shown in Fig. 1 needs diagonal elements for stability. For the loading condition shown add. diagonal element in an arrangement such that all diagonals are in a state of tension. What is the miudmum force in the diagonal 10
.<img src='./qimages/1471-1b.jpg'>
A box of mass 150 kg moves down on a rough inclined plane at a velocity of 4 m/sec .when a force P is applied as.shown in -Fig.2(a).The force P varies with time as shown in Fig.2(b). Calculate the time elapsed when the velocity of box is zero. Coefficient of friction mew 0·3.g=9·81 m/sec2.
<img src='./qimages/1471-1c.jpg'>
Calculate the diameter of a parachute in the form of a hemispherical shell to be used for dropping a small object,of mass 90 kg so that it touches the Earth at a maximum velocity of 6 m/sec. The drag coefficient for the hemispherical shell with its concave'side upstream is 1·32 for Re> 103. Air density 1·22 kg/m3.10
For the given velocity profile, determine whether flow is attacheq, detached or on the verge of separation. The velocity profile is
<img src='./qimages/1471-1e.jpg'>
where u Velocity at distance y
omegha :Boundary layer thickness
U Free stream velocity. 10
2.(a)A shaft is made up of partly solid section and partly hollow section as shown in the Fig. <img src='./qimages/1471-2a.jpg'> What iS the maximum torque that can be transmitted when maximum shear stress is 80. GPa, with modulus of rigidity 80 GPa What is the maximum free end rotation? 12
A 50 mm cube is subjected to uniform pressure of 200 mPa. When the change dimension between two parallel faces of the cube is 0·025 mm
determine the change in volume of the cube. Poisson's ratio mew 0·25. 8
A,fixed beam of 2·4 m has been 'loaded as shown in Fig. The cross-section is uniform tee as shown Fig. The load on the span is increased to when plastic hinges are formed at A and B. What is the magnitude of and what is the maximum deflection corresponding to this' load? E 200 GPa, Yield strength fy= 250 'mPa. 20
<img src='./qimages/1471-2c.jpg'>
By direct stiffness method, analyse the pin jointed frame shown in Fig. 5. Take AE=1. Determine forces in all members. Find joint displacements at O. 20
<img src='./qimages/1471-3a.jpg'>

(b)State at least five conditions for channel.flow to be critical. 5
For a critical flow in a rectangular channel prove that:
x2y2=q2/8g
where x is top width
y is the distance of the water surface below energy line
Discharge.in the channel.10
A lock sluice at a dam has a surface width of 1·0 m and cross-sectional area of 1·25 m2 at the critical depth. What velocity of flow would correspond to critical depth? 5
A pump is needed to operate at 3000 rpm with a lift of 7 m and a discharge of 0·15 m3/sec. Calculate the sp'ecific speed; determine which among the following is most suited:
1. Reciprocating pump 2. Centrifugal pump
3. Mixed flow pump and 4. Axial flow pump.
At its normal operating point a centrifugal pump with one stage delivers 0·3 m3/sec against a head of 30 m at a speed of 1500 rpm. At another site it is required that 0·4 m3/s be raised over a height 105 by using a similar pump operating at the same speed but with multi stages in series (one after the other). How many stages are required? 12

A hydro electric scheme has a 10m diameter
tunnel 1700 m long within which water flows
with a mean velocity of 5 connected to the
tunnel is a surge shaft. Estimate the rise in
water level in the shaft following sudden
closure of the valves leading to the turbines.
Neglect the energy losses. 12
The boundary layer thickness at a distance of
1·0 m from the. leading edge of a flat plate kept
over zero angle of incidence to the flow direction
is 1·0 mm. The velocity out side the boundary
layer is 25 m/sec. Calculate the boundary layer
thickness at 4 m from the leading edge. Assume
that the boundary layer is entirely laminar. 8

SECTION .B
5.Attempt any four of the following lOx4 =40
Determine the ultimate moment of resistance for an r.c. beam given the following data: Width of beam =300 mm; Total depth =600 mm Effective cover 50 mm; Tension steel consists of 4 bars 25 mm diameter. M 20 concrete and Fe 415 steel are used.
<img src='./qimages/1471-5a.jpg'>
Design a stanchion 2·4 m long to carry. an axial load of 180 kN. The ends of the column are restrained in position and direction.. f 250 N/sq.mm, Properties of available sections and permissible compressive stress (sigma ac) for various slenderness ratios (lamda) are given in the tables below.:
<img src='./qimages/1471-5b.jpg'>
(i)State the purpose. of mix design for concrete and list out four important factors
influencing the strength of concrete. 5
Compute the porosity of sand in the loosest possible state, considering'it to he made up of equal diameter spherical particles. 5
During a compaction test, a soil attains a maximum dry density of 18·6 kN/m3 at a "moisture content of 15%. Taking specific gravity of soil as find the degree of saturation and percentage air voids at maximum dry density. What will be the dry density corresponding to zero· air voids at o.m.C. 10
smooth vertical wall 6 m high retains a cohesionless backfill with, horizontal surface. The properties of the fill are e cP=30° • and G 2·65. Compute the magnitude of total lateral pressure for dry backfill when
the wall is restrained against yielding.
(ii)the wall is free to yield.
the wall is pushed towards the backfill. 10
Design the roof slab for a room of size 4mx 9m. The slab is supported by one brick wall all around live load is 3 kN/sq.m and load due to floor finish is 1 kN/sq.m. 20 M20 concrete and Fe 415 steel are used. Modification .factor kt for percentage of tension steel are given in the below:
<img src='./qimages/1471-6a.jpg'>
Design the vertical wall of a circular r.c. tank with flexible base resting on ground for a capacity of 500 kilo litres. The height of the tank with 0·2m free board 184m. Calculate the vertical and horizontal reinforcements for 1 m height from the base. Concrete grade M 20 and Fe 415 steel are used. 12
A tie member in a truss consists of two angles 150 x 115 x 10mm with long .legs connected to a gusset plate by 20 mm diameter rivets such that each angle section is reduced in section by one rivet hole.
Area of section of one angle 2552 sq.mm. 8
State the need for provision of stiffners in plate girders .and list Qut three types of stiffners. 4
An ISMB 300 ,beam ,is supported over a span of 5 m. It carries a concentrated load of 300 kN at midspan section. Length of bearing plate below the load is 200 mm. Length of bearing plate at support iS 120 mm. fy= 250 N/sq.rnm. Permissible stress in bearing= 185 N/sq.mm. Depth of .. root filling h2 29·25 mm. Thickness of. web tw 7·7 mm Is the design above, with respect to the bearing, safe? 6
State the reasons for using high tension
steel in prestressed concrete and list out
the forms of availability of this steel. 4
Modular bricks (190 x 90 x 90 mm) are
used to construct a brick wall of 200 mm
thickness. The wall carries an axial load of
50 kN/m from the wall above it and a load
of 36 kN/m ·from the roof slab acting at a
distance of 47·5 mm from the centre-of the
wall. Determine the maximum and •
minimum stresses in the wall. 6
Upto what depth can an excavation be made • vertiCally without support in a cohesive soil with c 30kN/m2 pie =10 and y =19 kN/m3• What will be the depth upto which tension crack may develop If the tension crack develops, will the above computed depth of excavation be safe? Why? 8

A stratum of saturated clay 2.7) has an initial water content of 44 percent throughout its depth. after a long dry spell, the water content at the ground surface is 20% and at 3 the water' content is 44%. The water content may be taken to vary linearly with depth. The shrinkage limit of the clay is 28%. If the change in height per unit height of the clay (delta is 80% of its change in volume. per unit volume· (deltav/v0).what is the
amount of settlement of the ground surface due to change in water content which occurred? 12
The footing of a wall. is 1·2 m wide at the base and is located in a homogeneous cohesive soil at a depth of 1 m below G.L. The soil has y =17.6 kN/m3, =36 kN/m2 and pie= 20°. Assuming the soil as soft which is likely to fail under local shear, determine the safe load which can be taken by the footing per metre length of the footing,
.Explain 'Quick Sand' condition with a neat
.sketch. Obtain the critical gradient expression for this condition, The submerged unit weight of fine . sand is 9·9 kN/m3. Compute the critical gradient for the fine sand. 8+5
group of sixteen piles arranged in a square pattern is to proportioned in a deposit of soft saturated clay. Assuming piles to be square (with side 300 rom) and 12 ill long, work out the spacing of piles for 100 percent efficiency of the 'pile group. Take mobilisation factor of 0·8 and consider both point bearing and skin friction.