Ser·Ace Exam
auon·20t2 . 1 1

Paper I
Time Allowed: Three Hours I I Maximum Marks 200 I'·
INSTRUCTIONS
Candidates should attempt Question Nos. 1 and 5 which are compulsory and any THREE of tile remaining questions, selecting at least ONE question from each Section. Assume suitable data, if considered necessary, and indicate tile same clearly. Standard notations are given in tile questions a11d, these twtatio11s have their usual meanings, unless otherwise indicated. All questions have equal marks. Marks allotted to each part/sub-part of a question are indicated against each. Answers must be written in ENGLISH only. Neat sketches may be drawn, wherever required. Important Note All parts/sub-parts of a question must be attempted contiguously. That is, candidates must finish attempting all the parts I sub-parts of each question they are answering in the answer-book before on to the next question. Pages left blank must be clearly struck· out. Answers that follow any pages left blank may not be given credit. (Contd.)

Section- A
1. Explain principle of superposition with
an example. 4
State the nature of failure of columns
with the relevant equations ·related to
stress. 4
Draw qualitatively (without any calculatio.l_l),
the deflected shape and BM diagram for any
two of the following structures 8
p
Hinge Roller
•
• m /unit length
I
Hinge Hinge
D-GT-M-DFA 2 (Contd.)
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.
p p
A
I· 2L L 2L
Generate the stiffness matrix for the beam
element shown in the following figure for the
degrees of freedom 2 and 3. 8
EI constanf
1 1
A cohesionless soil has a permeability of
0·03 em/sec at a void ratio of 0·32. Make the
predictions for the permeability of this soil at
a void ratio of 0·42 according to functions of
void ratio that are proposed. 4+4
A pelton wheel develops power of
4470 kW under a head of 122 m at a
speed of 200 r.p.m. Assume Cv ·98,
¢ 0·46, efficiency 88% and wheel
diameter to jet diameter ratio of 9. Find
the discharge required, diameter of wheel
· and diameter-of jet and number of jets.
D-GT-M-DFA 3 (Contd.)
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2.
For a wide horizontal Rectangular
channel, assuming Chezy's coefticient C
to be constant in G.V.F.
Prove that
x c
2 l ]+constant
g
where y is depth of flow
and Yc is the critical depth. 4+4
4MN
400kN

50mm
250mm
2MN
z
y
A metallic bar 250 mm x 100 mm x 50 mm is
loaded as shown in the. above figure. Work out
the change in volume. What should be the
change that should be made in the 4 MN load
in order that there should be no change in the
volume of the bar? AssumeE-:2 x HP N/mm2
and Poisson's ratio= 0·25. 15
D-GT-M-DFA 4 (Contd.)
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A crane chain having an area of 7 · 25 cm2
carries a load of 15 kN. As it is being lowered
at a uniform rate of 50 m per minute, the chain
gets jammed suddenly, at which time the·
length of chain unwound is 12m. Estimate the
stress induced in the chain due to the sudden
stoppage. Neglect the weight of the chai'n.
Assume E 2·1 x loS N/mm2. 10
Find the diameter of a solid cylindrical shaft
subjected to 100 rpm and transmitting 350 kW
power, wherein the shear stress not to exceed
,90 N/mm2.
What per cent saving in weight would be
obtained if this shaft is replaced by a hollow
one, whose internal diameter equals to 0·65 of
the external diameter, the length, the material
and maximum shear stress being the same.
15
3. Design a reinforced concrete beam of
rectangular section to carry a superimposed
load of 32 kN I m over an effective span of 8 m.
Overall depth of beam is restricted to 650 mm
for architectural reasons. Width of the beam is
300 mm. Effective cover to reinforcement is
50 mm. M 20 concrete and Fe 415 steel are
used. Use limit state method.
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Modification factor for different percentage of
tension steel


.
0·6 07 0·8 0·9 1·0 1-1 1·2 1·3 1·4 1·5 1·6
1-16 I-ll 1·07 1·03 I 0·98 0·95 0·94 0·92 0-90 0·89
Modification factor Kcfor different percent'!gi!
of compression steel
0·15 0·2 0·3 0·4 0·5 06 07 0·8 0·9 1·0
Kc 1·05 1·09 1-12 1·14 1·17 1·19 1·21 1·23 1·27
Design shear strength Tc for concrete of M 20
grade.
%of sleel 0,9 1·0 1-2 1-3 1·4 1·5 1-6
N/sq.mm 0-6 0-62 0-64 0-66 0-68 0-7 0-72 0-73
20
A r.c. retaining wall is required to retain earth
for a height of 4 m above ground level. Top
surface of the earth retained is horizontal.
Density of earth is 18 kN/cu.m and the angle
of repose of the soil is 30°. Safe bearing
capacity of soil is 200 kN I sq.m and coefficient
of friction between concrete and earth 0·6.
Select suitable dimensions for the components
of the retaining wall and check the stability of
the wall. Design the vertical stem only using
M20 concrete and Fe 415 steel. Provide a
sketch indicating the reinforcements in the
stem. 20
0-GT-M-DFA 6 (Contd.)
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4. A 8·0 m high retaining wall supports a soft
saturated clay as backfill. The shear strength
parameters obtained in undrained conditions
were Cu 19·5 kN/m2 and lflv 0. If unit
weight of soil is 18 kN/m3. Find
The maximum depth of tensile crack
5 •
The active force before the tensile crack
occurs 5
The active force after the occurrence of
tensile crack 5
0
Design a square pile group to carry a load of
400 kN in a clay strata with unconfined compressive
strength of 60 kN/m2. The piles are
30 em in diameter and 6·0 m long. Adhesion
factor may be taken as ·58. IS
A 11·5 m high embankment is inclined on
sides at angle 30° to the horizontal. If the
shear strength parameters of the soil are
C 20. kN/m2 and ·1/1 determine the
factor of safety available against slope failure.
The unit'weight of soil is 20 kN/m3. The value
of Sn from Taylor Chart for 1/1 20 and fJ 30
is 0·025. 10
Section- B
5. A pretensioned beam 240 mm wide and
300 mm deep is prestressed by 12 No. H.T.
wires each of 7 mm diameter initially stressed
to 1200 N/mm2 with their centroid ·located
D-GT-M-DFA 7 (Contd.)
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100 mm from the soffit. Estimate the final
percentage of loss of stress due to elastic
shortening, creep of concrete, shrinkage of
concrete and relaxation of H.T. steel on the
basis of following data
210 kN/mm2,
E 35 kN/mm2,
Creep coefficient 1·6,
Residual shrinkage strain 3 x I o-1 and
Relaxation of steel stress 90 N/mm2. 8
b
Jb
h
Jb
Calculate the shape factor and the fully plastic
moment MP of the section shown in the above
figure. Assume yield stress ay in both tension
and compression. 8
D-GT-M-DFA 8 (Contd.)
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· Explain soundness of cement and describe the
procedure to determine the soundness of
cement. 8
6.
Establish the relationship for shear strength in
case of Vane shear test.
T 2T
nd3(h+dl3)
where h is height of vane
d is the diameter of vane
Tis torque
T1 is shear strength of soil 8
Give at leas't two important uses and limitations
of flow nets. Name four approximate
methods of Drawing flow nets. 8
.!"ge
A lm B c
15. £it 9
4m 4m 4m . 14 •I• 4m •I
Draw influence line diagrams for the vertical
reaction at support B and BM and SF at section
m of the beam shown in the above figure using
MUller-Breslau principle or otherwise. Plot the
values of the ordinates at few sections along the
beam. Calculate the maximum values of the
above functions when 2 wheel loads of 5 kN
each placed I m apart cross the beam. 15
D-GT-M-DFA 9 (Contd.)
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2P P


a a a
Calculate the collapse load for the beam
shown in the above figure by both mechanism
method and statical method.
Assume the beam to be of constant section, the
fully plastic-moment being MP. 25
•
7. A rectangular channel 3 m wide and 1·8 metre
deep discharging 18 m3 suddenly has its
discharge reduced to 12 m3 /sec at the down
stream end.
Compute the speed and height of the surge
moving D/s. 10
Give at least ten practical applications of
hydraulic jump. 10
A four stage reciprocating pump has cylinders
of 400 mm diameter and stroke of 600 mm
each. The pump has to deliver 0·5 m3 sec
of water at an elevation of 300 m above the
sump level. The friction loss in delivery and
suction pipes are 25 and 5 metres. Take
velocity of water in deli very pipe as 2 sec,
efficiency 0·8 and slip is 2%. Compute the
speed and power required to drive the pump.
10
D-GT-M-DFA 10 (Contd.)
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Show that for a hydraulic jump in a horizontal
frictionless rectangular channel
Fr 2 8

Frr-
8. A normally consolidated clay stratum with
liquid limit of 42% and 6·4 m thickness is
located at a depth of 9·5 m below the present
existing ground surface. The clay has natural
moisture content of 35% and has a specific
gravity of 2·68. The subsoil consists of very
fine sand between the ground surface and clay.
The water table is located at 3·5 m below the
ground surface.
Unit weight of sand above the water table is
18 kN/m3. Average submerged unit weight of
sand is II kN/m3. A new building is to be
constructed at the ground level and it exerts an
effective increased overburden pressure on
clay by 40 kNfm2.
Estimate the settlement of building. 10
Crude oil is to be pumped at a rate of
18 m3/ hr, through a 100 metre long
pipe of diameter 0·3 m. The delivery
point of the pipeline is 5 metre vertically
above the entry point. The specific
gravity of the crude oil is equal to 0·86
and kinematic viscosity is 0·135 X J0-4
m 2/sec. Calculate
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Maximum velocity of the oil in the
ptpe
The frictional head loss
The power required to pump the
oil
Explain the significance of "Knudsen"
number.
Distinguish between pre-tensioned and
post-tensioned pre-stressed concrete
clearly describing the step by step
procedures involved. I 0
Explain laterally unsupported beams. 5
Two channels of ISMC 400 at 49-4 kg/m
placed back to back are used as a
laterally supported beam over a span of
6·0 m (simply supported). It is subjected
to a Jl. d. I. of I tIm and two concentrated
loads ofF each at I 13 points. If 1600
kg/cm2 find F and also the maximum
deflection in the beam.
0-GT-M-DFA
Find an equivalent 1-Beam to support the
same load over the same span. Comment
on the efficiency of the sections in 0 .
resisting the loads.
0
Properties of the channel section ISMC
400:
Z 754·1 cm3 I 15082·8 cm 4
. u
Properties of 1-Beam-ISLB 500 at
75 kg/m.
I xx 38579 cm 4
Zxx 1543·2 cm4 . 15
12
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