2018 September - Afternoon
1. For reinforced concrete vertical column, with hinge ends, is applied with end moments and lateral load as shown in the figure. Column high is 10 ft. The shear force at mid-height of the column ( 5 ft from column end ) according to applied loads will be almost equal to _____. Neglect own weight of the column.
(a) 5.0 kips
(b) 4.0 kips
(c) 2.0 kips
(d) 8.0 kips
Ans:
∑ moment at B = 0
RAX × 10 + 20 + 20 = 1 × 10 × 5
RAX = 1 kip
RBX = ( 1× 10 ) - 1 = 9 kip
Shear force at mid-height of the column
Vmid = 9 - ( 1 × 5 )
= 4 kip [ → ] (b)
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2. For the truss as shown in figure, bar force in member AC and bar force in member CE will be almost equal to _ _ _ _ _ according to applied load at point E.
CE 3.487 kips (compression)
(b) AC 2.857 kips (compression)
CE 2.857 kips (compression)
(c) AC 3.487 kips (tension)
CE 3.487 kips (tension)
(d) AC 3.487 kips (compression)
CE 3.487 kips (tension)
Ans:
∑ moment at B = 0 [ ⥅ ]
RAx×7 + 2×10 = 0
RAx = 0
RAx = - 2.857 kips
RAx = 2.857 kips [ ← ]
@ Joint A,
∑ Fx = 0 [ ⥅ ]
10/12.207 FAC - RAX = 0
10/12.207 FAC - 2.857 = 0
FAC = 3.488 kips
[ Tension ]
@ Joint E,
∑ Fy = 0 [ ↑+ ]
12.207/7 FCE - 2 = 0
12.207/7 FCE - 2 = 0
FCE = 3.488 kips
[ Tension ] (c)_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
3. For the beam as shown in figure, shear force at point C according to applied loads will be almost equal to _ _ _ _ _. (Neglect own weight of beam)
(a) 544.43 lb
(b) 538.55 lb
(c) 556.32 lb
(d) 525.42 lb
Ans:
∑ moment at D = 0 [ ⟳+ ]
0 = RA × 10
- 14 × 400 × 14 × 1/2
- 1/2 × 14 × 600 × 14 × 1/3
RA = 5880 lbs
14' ----- 600 lb
9' ----- ?
= 600 × 9/14
= 385.71 lbShear Force @ point C [ ↑+ ]
= RA - ( 9 × 400 ) - ( 1/2 × 9 × 385.71 )
= 5880 - ( 9 × 400 ) - ( 1/2 × 9 × 385.71 )
= 544.305 lb (a)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
4. For the truss shown in figure, vertical reaction at support E and bar force in member DF will be almost equal to _ _ _ _ _ according to applied loads.
Vertical Reaction at E
Bar Force in member DF
(a) 2.0 kips (downward)
4.0 kips (Tension)
(b) 4.0 kips (upward)
4.0 kips (Compression)
(c) 2.0 kips (upward)
3.0 kips (Tension)
(d) 4.0 kips (downward)
2.0 kips (Compression)
Ans:
∑ Fx = 0
RFx = 2 kips [ ← ]
∑ moment at E = 0 [ ⟳+ ]
0 = 2 × 20 - RFy × 10
RFy = 4 kips [ ↑ ]
REy = 4 kips [ ↓ ]
@ Joint E,
FEF = 0
@ Joint F,
∑ Fx = 0 [ ⥅ ]
0 = 1/√2 FCF - RFx
FCF = 2√2 kips [ ← ]
∑ Fy = 0
0 = RFy - /√2 FCF - FDF
FDF = 4 - 1/√2 × 2√2
= 4 (Compression)
(d)
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5. For the simply supported steel beam W10×45 is made of A-36 steel with the factored uniformed distributed load as shown in figure. The possible maximum span length L(ft) to carry the applied loads with the following given data will be almost equal to _ _ _ _ _.
Use LRFD method with A-36 steel for the beam.
Assume compact section
Assume applied loads ωu are total factored loads.
No need to check deflection.
Span Length L
(a) 21.0 ft
(b) 24.0 ft
(c) 28.0 ft
(d) 32.0 ftAns:
ωu = 1.5 kip/ft
= 1.5 × 12 = 18 kip-in
A-36 Steel
Fy = 36 ksi
From AISC Manual (2017)
W10×45
Zx = 54.9 in3
Mn = Fy Zx - - - F2-1 (AISC 360-16)
ΦMn = Mu
ΦFy Zx = ωu L2 / 8
0.9 × 36 × 54.9 = 18 × L2 / 8
L = 337 in = 28 ft (c)
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6. Cantilever steel beam W14×19 made of A-36 steel is loaded as shown in figure. The possible maximum Pu (total factored load) to be carried by this beam section will be almost equal to _ _ _ _ _ with the following data;
Use LRFD method with A-36 steel for the beam.
Assume compact section
Assume applied load Pu and ωu are total factored loads.
No need to check deflection.
Load Pu
(a) 50 kips
(b) 45 kips
(c) 59 kips
(d) 65 kipsAns:
ωu = 0.6 kip/ft
A-36 Steel
Fy = 36 ksi
From AISC Manual (2017)
W14×90
Zx = 157 in3
Mn = Fy Zx - - - F2-1 (AISC 360-16)
ΦMn = Mu
ΦFy Zx = ωu L2 / 2 + P . L
0.9×36×157/12= 0.6×82/2 + P×8
P = 50.59 kip (a)
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7. For the connection as shown in figure, total design strength for double shear of the 5/8 in. diameter four nos. of A-325 X (threads are excluded from shear planes) bolts will be almost equal to _ _ _ _ _ with the following data.
6" × ³/₈" Plates made of A-36 steel.
No need to check other design strength, plate tensile strength, bearing strength, etc.
Assume bearing type connection. Use AISC & LRFD method.
Double shear strength of Bolts
(a) 14.35 kips
(b) 114.87 kips
(c) 28.7 kips
Ans:
AISC LRFD Specification (1986)
When threads are excluded from shear plane
Rn /mAb = 0.60 Fu _ _ _ C-J3-2
number of shear plane, m = 2
Ab = π (5/8)2 / 4 = 0.3068 in2
From Table J3.2,
Resistance factor Φ for A325 → 0.65
Fracture Strength Fu for A325 → 120 ksi
ΦRn = Φ 0.60 Fu m Ab
= 0.65 × 0.6 × 120 × 2 × 0.31
= 28.7165
For 4 bolts → 4 × 28.7165
= 114.87 kips (b)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
8. The concentrically loaded reinforced concrete short column is reinforced with 10 #7 (0.875 in. dia.) main bars and 2 #3 (0.375 in. dia.) at 6 in. (center to center) tie bar as shown in figure. The design shear strength (Φ Vs ) in Y direction carried by tied reinforcement of this column section is almost nearly equal to _ _ _ _ _.
Given data
d = 11.5" (Y direction)
fy = 50 ksi, f'c = 4 ksi (28 days)
Use ACI code
Use strength reduction factor 0.85 for shear
Design Shear Strength (ΦVs )
(a) 31.0 kips
(b) 46.0 kips
(c) 42.0 kips
(d) 36.0 kips
Ans:
Tie bar diameter = 0.375"
A = π (0.375)²/4 = 0.11 in²
For Y direction,
AV = 4 × 0.11 = 0.44 in²
fy = 50 ksi
d = 11.5" (Y direction)
Tie bar spacing,
s = 6" (center to center)
Vs = AV fy d / s _ 11-15 (ACI 318-95)
22.5.8.5.3 (ACI 318-19)
= 0.44 × 50 × 11.5 / 6
= 42 ksi (c)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
9. The fixed end cantilever reinforced concrete slab is applied uniformly distributed load 1100 lb/ft including own weight as shown in figure. The most suitable minimum concrete compression strength f 'c (28 days) will be almost equal to _ _ _ _ _, to carry the applied loads without shear reinforcement with the given data.
Given data
slab thickness h = 7.5"
effective depth d = 6.5"
no shear reinforcement
consider 12" slab width
Use ACI code.
Use strength reduction factor 0.85 for shear
no need to consider the effect of axial force and bending moment.
Concrete compression strength f 'c (28 days)
(a) 2,500 psi
(b) 3,500 psi
(c) 4,000 psi
(d) 4,500 psi
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
10. A Planning Engineer is to allocate duration for superstructure work (typical floor) which can be broken down as follow. The detailed construction drawings are available for all activities. The logic of all activities are finish-to-start except an activity is possible to have an early start.
(i) Erection of formwork: three days
(ii) Prefabrication of beam reinforcement cages: two days
(iii) Delivery & installation of beam reinforcement: two days
(iv) Installation of slab rebar & concealed services: three days
(v) Provision of slab opening, CJ, and reference level on FWK: two days
(vi) Cleaning & casting of floor beam & slab: one day
Please identify which activity can start early and advise the total duration required?
Ans:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
11. The following table is an activity list include the duration and predecessor for a series of project activities. What is the critical path for these activities and duration of project?
|
ACTIVITY
|
DURATION (weeks) |
PREDECESSOR
|
|---|---|---|
| A | 2 | Start |
| B | 4 | A, E |
| C | 6 | A |
| D | 3 | B, C |
| E | 7 | Start |
| F | 2 | E |
| End | - | D, F |
Ans:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
12. Please verify the following statements are True or False?
Site investigation (Soil test) is required before structural design work.
Contiguous bored piles are only used for main building foundation and not used for temporary earth retaining structure.
Engineers who involved in work site management team are need not to care about work site safety.
Construction site safety should be managed by qualified HSE officers or safety supervisors.
Ensuring formwork quality is more important than checking slump test of concrete prior to casting of reinforced concrete work in order to have quality.
Ans:
True
False
False
True
False
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
13. Please fill in the blank with the most appropriate words given.
A planning engineer should understand _ _ _ _ _ when he does scheduling of all work activities.
Purchasing department should prepare and monitor _ _ _ _ _ _ _.
HSE officer should implement and enforce _ _ _ _ _ _ _.
Project management shall consider _ _ _ _ _ for all new development projects.
A quantity Surveyor shall include _ _ _ _ _ for budget control and monitoring.
(a) Safe work procedures
(b) Workplace safety management plan and regulation
(c) Procurement plan
(d) Work breakdown structure
(e) Environmental protection plan
(f) Cash flow plan
Ans:
(d)
(c)
(a)
(b) and (e)
(f)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
14. A saturated soil has a void ratio of 0.5 and a specific gravity of solid soils, Gs = 2.54. The moisture content of the soil is most nearly:
(a) 19%
(b) 20%
(c) 21%
(d) 25%
Ans:
S = ω Gs / e _ _ _ 1.39 (Das, 2013)
e = ω Gs / S
for saturated soil, S = 1,
e = ω Gs _ _ _ 1.40 (Das, 2013)
ω = e / Gs
ω = 0.5 / 2.54
= 0.2 = 20%
(b)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
15. The blow count for SPT test at a depth of 6m in coarse-grained soil at every 0.15m are 12 and 15. A donut hammer (free-fall) (China) and a standard sampler were used in a borehole 150mm in diameter. The corrected N value for rod length, sampler type, borehole size, and energy ratio to 60% is approximately:
(a) 24
(b) 27
(c) 30
(d) 33
| Hammer | Release | ERr% | ERr/60 | |
|---|---|---|---|---|
| Japan |
Donut Donut |
Tombi 2 turns of rope |
78 65 |
1.3 1.1 |
| China |
Pilcon type Donut |
Trip Manual |
60 55 |
1.0 0.9 |
| USA |
Safety Donut |
2 turns of rope 2 turns of rope |
55 45 |
0.9 0.75 |
| UK |
Pilcon, Dando, old standard |
Trip 2 turns of rope |
60 50 |
1.0 0.8 |
|
Rod length: > 10 m 6-10 m 4-6 m 3-4 m |
1.0 0.95 0.85 0.75 |
|
Standard sampler US sampler without liners |
1.0 1.2 |
|
Borehole diameter: 65-115 m 150 m 200 m |
1.0 1.05 1.15 |
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
16. The wet mass of one of the standard Proctor test samples is 1806 grams at water content of 8%. The volume of the standard Proctor test sample is 9.44 × 10-4 m3. The dry unit weight is approximately:
(a) 15 kN/m3
(b) 17 kN/m3
(c) 19 kN/m3
(d) 21 kN/m3
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
17. The stresses on a failure plane in a drained test on a cohesion-less soil are as under; Normal stress = 100 kN/m2 , Shear stress = 40 kN/m2. The angle which the failure plane makes with the major principal plane is about:
(a) 48°
(b) 52°
(c) 56°
(d) 60°
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
18. Classify the following soil by the unified soil classification system.
Percent passing No. 10 sieve = 95
Percent passing No. 40 sieve = 90
Percent passing No. 100 sieve = 70
Percent passing No. 200 sieve = 65
Liquid limit = 55
Plasticity index = 30
(a) CH
(b) MH
(c) OH
(d) CL
Ans:
Fig. Casagrande's plasticity chart (Holtz & Kovacs, 1981)
Liquid limit = 55
Plasticity index = 30
(a)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
19. A 35 mm cast iron pipeline of length 5 km carries 0.4 m3/s between two constant head reservoirs. If it is desired to increase the flow rate to 1.4 m3/s by replacing the existing pipeline with a new one of the same material. [Assume f = 0.02 and hf = fLV2/2gD. Neglect all minor losses.] The size of the new pipeline is
(a) 75.00 mm
(b) 60.50 mm
(c) 57.70 mm
(d) 70.50 mm
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
20. Water flows at 8 m3/s through a rectangular channel 4 m wide and 3 m deep. The flow velocity is 1 m/s. If this channel expands (downstream) to a width of 5 m and the depth is decreases by 0.5 m from the upstream depth, the velocity in the expanded section is
(a) 2.07 m/s
(b) 1.97 m/s
(c) 1.07 m/s
(d) 0.97 m/s
Ans:
A1 = 4 × 3 = 12 m2
V1 = 1 m/s
A2 = 5 × 2.5 = 12.5 m2
By continuity equation,
(Munson et al., 2013)
A1V1 = A2V2 _____3.19
12 × 1 = 12.5×V2
V2 = 0.96 m/s (d)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
21. A 6 hours storm had 4 cm of rainfall and the resulting runoff was 2 cm. If ϕ index remains at the same value, the runoff due to 10 cm rainfall in 12 hours in the catchment is
(a) 4.5 cm
(b) 6.0 cm
(c) 7.5 cm
(d) 9.0 cm
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
22. The form factor of a drainage basin is obtained by dividing
(a) area of the basin by the axial length
(b) average width of the basin by the axial basin
(c) area of the basin by the square of the axial length
(d) both (b) and (c)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
23. Pick up the incorrect statement:
(a) Water table rises and falls with seasons
(b) Level of water table remains stationary in different season
(c) Free surface of ground water is subjected to atmospheric pressure
(d) Depth of water table is directly proportional to the rate of withdrawal of water
Ans: (b)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
24. Which is the incorrect statement when iron concentration in water is higher than the allowable:
(a) Makes water reddish in color
(b) Causes discoloration of clothes
(c) Causes incrustation of water pipes
(d) Makes water pleasant to taste
Ans: (d)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
25. The required chlorine dosage is 3.0 mg/L. Determine the amount of Bleaching Powder having an available chlorine of 20% if it is to be used as the disinfectant:
(a) 10.0 mg/L
(b) 12.0 mg/L
(c) 15.0 mg/L
(d) 20.0 mg/L
Ans:
Required amount of bleaching powder,
= 3 × 100 / 20 = 15 mg/L (c)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
26. COD determined by using potassium dichromate will generally have a BOD5/COD ratio of:
(a) BOD5/COD < 1.0
(b) BOD5/COD > 1.0
(c) BOD5/COD = 1.0
(d) None of the above
Ans: (a)
BOD₅/COD < 1 (Von Sperling, 2007)
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