In pre-stressed concrete
Forces of tension and compression change but lever arm remains unchanged
Forces of tension and compressions remain unchanged but lever arm changes with the moment
Both forces of tension and compression as well as lever arm change
Both forces of tension and compression as well as lever arm remain unchanged
Correct Answer :
B. Forces of tension and compressions remain unchanged but lever arm changes with the moment
Related Questions
During erection, the pile of length l is supported by a crane at a distance of
0.207 l
0.293 l
0.707 l
0.793 l From the driving end of pile which rests on the ground
The factor of safety for
Steel and concrete are same
Steel is lower than that for concrete
Steel is higher than that for concrete
None of the above
For the design of retaining walls, the minimum factor of safety against overturning is taken as
1.5
2.0
2.5
3.0
The minimum cover in a slab should neither be less than the diameter of bar nor less than
10 mm
15 mm
25 mm
13 mm
According to Whitney's theory, depth of stress block for a balanced section of a concrete beam is limited to
0.43 d
0.537 d
0.68 d
0.85 d Where d is effective depth of beam
If 20 kg of coarse aggregate is sieved through 80 mm, 40 mm, 20 mm, 10 mm, 4.75 mm, 2.36 mm, 1.18 mm, 600 micron, 300 micron and 150 micron standard sieves and the weights retained are 0 kg, 2 kg, 8 kg, 6 kg, 4 kg respectively, the fineness modulus of the aggregate, is
7.30
7.35
7.40
7.45
To determine the modulus of rupture, the size of test specimen used is
150 × 150 × 500 mm
100 × 100 × 700 mm
150 × 150 × 700 mm
100 × 100 × 500 mm
According to IS: 4561978, minimum slenderness ratio for a short column is
Less than 12
Less than 18
Between 18 and 24
More than 24
For preparing a test-specimen, it is necessary
To mix cement and fine aggregate by dry hand
To mix coarse aggregates
To mix water to the cement, fine aggregates and coarse aggregates
All the above
Slump test of concrete is a measure of its
Consistency
Compressive strength
Tensile strength
Impact value
Workability of concrete for a given water content is good if the aggregates, are
Rounded aggregate
Irregular aggregate
Angular aggregate
Flaky aggregates
The minimum diameter of longitudinal bars in a column is
6 mm
8 mm
12 mm
16 mm
The type of aggregates of same nominal size, which contain less voids when compacted, are
Rounded spherical
Irregular
Flaky
None of these
According to IS : 382-1963, a good aggregate should be
Chemically inert
Sufficiently strong
Hard and durable
All the above
The property of fresh concrete, in which the water in the mix tends to rise to the surface while placing and compacting, is called
Segregation
Bleeding
Bulking
Creep
Transport of concrete by pumps, is done for a distance of
100 m
200 m
300 m
400 m
Air entrainment in the concrete increases
Workability
Strength
The effects of temperature variations
The unit weight
For concreting tunnel linings, transportation of concrete is done by
Pans
Wheel borrows
Containers
Pumps
For a good concrete
Aggregates should be hard and durable
Water should be free from organic materials
Cement should be sufficient to produce the required strength
All the above
The entrained air in concrete
Increases workability
Decreases workability
Decreases resistance to weathering
Increases strength
To obtain a very high strength concrete, use very fine grained
Granite
Magnetite
Barite
Volcanic scoria
The 28 days cube strength of mass concrete using aggregates of maximum size 5 cm for gravity dams should be
Between 150 to 300 kg/cm2
Between 350 to 600 kg/cm2
Between 150 to 500 kg/cm2
Below 200 kg/cm2
The commercial name of white and coloured cement in India, is
Colorcrete
Silvicrete
Snowcem
All the above
For quality control of Portland cement, the test essentially done is
Setting time
Tensile strength
Consistency
All the above
Setting time of cement increases by adding
Gypsum
Hydrogen peroxide
Calcium chloride
Sodium oxide
Horizontal construction joints in concrete walls are generally provided at
Soffit level
Window sill level
Floor level
All the above
On a grading curve, the gap grading is represented by
A horizontal line
A vertical line
N.W. inclined line
N.E. inclined line
Batching error means inaccuracy in the quantity of
Aggregates
Cement
Water
All the above
The individual variation between test strength of sample should not be more than
± 5 % of average
± 10 % of average
± 15 % of average
± 20 % of average
In reinforced concrete footing on soil, the minimum thickness at edge should not be less than
100 mm
150 mm
200 mm
250 mm