GATE Technical: GATE 2016 Civil Engineering Set-2 questions with solutions

Q1. As per IS 456-2000 for the design of reinforced concrete beam, the maximum allowable shear stress (τ_max) depends on the

1. grade of concrete and grade of steel
2. grade of concrete only
3. grade of steel only
4. grade of concrete and percentage of reinforcement

Answer: grade of concrete only

The maximum allowable shear stress in reinforced concrete beams is primarily influenced by the grade of concrete, as it determines the material's strength and ability to resist shear forces. The grade of steel does not directly affect the shear capacity in this context.

Q2. A construction project consists of twelve activities. The estimated duration (in days) required to complete each of the activities along with the corresponding network diagram is shown below. Activity and duration (days): A Inauguration 1, B Foundation work 7, C Structural construction-1 30, D Structural construction-2 30, E Brick masonry work 25, F Plastering 7, G Flooring 25, H Electrification 7, I Plumbing 7, J Wood work 7, K Coloring 3, L Handing over function 1. The network diagram shows activities A, B, C, D, E, F, G, H, I, J, K, L connecting events 1 to 12, with a dummy activity from 4 to 5. Total floats (in days) for the activities 5-7 and 11-12 for the project are, respectively.

1. 25 and 1
2. 1 and 1
3. 0 and 0
4. 81 and 0

Answer: 0 and 0

The total float for an activity is the amount of time that it can be delayed without affecting the project's overall completion date. In this case, activities 5-7 and 11-12 are on the critical path, meaning any delay in these activities will directly impact the project's finish date, resulting in a total float of 0 for both.

Q3. A strip footing is resting on the surface of a purely clayey soil deposit. If the width of the footing is doubled, the ultimate bearing capacity of the soil

1. becomes double
2. becomes half
3. becomes four-times
4. remains the same

Answer: remains the same

For a purely clayey (phi=0) soil the bearing capacity factor N_gamma = 0, so the width-dependent term (0.5*gamma*B*N_gamma) drops out of the ultimate bearing capacity. Therefore doubling the footing width leaves the ultimate bearing capacity unchanged.

Q4. The relationship between the specific gravity of sand (G) and the hydraulic gradient (i) to initiate quick condition in the sand layer having porosity of 30% is

1. G = 0.7i + 1
2. G = 1.43i - 1
3. G = 1.43i + 1
4. G = 0.7i - 1

Answer: G = 1.43i + 1

The correct option establishes a linear relationship between specific gravity and hydraulic gradient, reflecting how an increase in hydraulic gradient influences the specific gravity needed to initiate quick conditions in sand with a given porosity.

Q5. The results of a consolidation test on an undisturbed soil, sampled at a depth of 10 m below the ground level are as follows: Saturated unit weight: 16 kN/m³ Pre-consolidation pressure: 90 kPa The water table was encountered at the ground level. Assuming the unit weight of water as 10 kN/m³, the over-consolidation ratio of the soil is

1. 0.67
2. 1.50
3. 1.77
4. 2.00

Answer: 1.50

With water table at the surface, gamma' = 16 - 10 = 6 kN/m3, so the current vertical effective stress at 10 m is 6*10 = 60 kPa. OCR = preconsolidation pressure / effective overburden = 90/60 = 1.5.

Q6. An elastic isotropic body is in a hydrostatic state of stress as shown in the figure. For no change in the volume to occur, what should be its Poisson's ratio?

1. 0.00
2. 0.25
3. 0.50
4. 1.00

Answer: 0.50

A Poisson's ratio of 0.50 indicates that the material is incompressible, meaning that any applied hydrostatic stress will not change its volume. This is characteristic of elastic isotropic materials under hydrostatic conditions.