A three-hinged arch is statically determinate because it has:
A
Three support reactions and three equations of equilibrium
B
Four support reactions and one additional equation from the internal hinge
C
Two support reactions at each end
D
Only vertical and horizontal reactions
Correct Answer:
B. Four support reactions and one additional equation from the internal hinge
Three-hinged arch has 4 reaction components (2 at each support) and 3 equilibrium equations plus 1 condition that moment at internal hinge = 0, making it statically determinate.
The shear force at the point of application of a concentrated load in a beam diagram shows a:
A
Smooth curve
B
Continuous line
C
Vertical discontinuity (jump)
D
Horizontal tangent
Correct Answer:
C. Vertical discontinuity (jump)
Shear force diagram shows a vertical jump equal to the magnitude of the concentrated load at its point of application.
For a continuous beam with different moments of inertia in different spans, the relative stiffness method uses:
A
Absolute I values
B
Relative stiffness (I/L ratios)
C
Average I value
D
Maximum I value
Correct Answer:
B. Relative stiffness (I/L ratios)
Relative stiffness (I/L) is used in distribution factor calculations when moments of inertia vary across spans.
In moment distribution method, the distribution factor for a member is proportional to:
A
Length of member
B
Stiffness of member
C
Load on member
D
Area of member
Correct Answer:
B. Stiffness of member
Distribution factor = (stiffness of member)/(sum of stiffness of all members at joint). DF ∝ stiffness (4EI/L).
The carry-over factor in slope-deflection method for a member with far end fixed is:
A
0.25
B
0.5
C
0.75
D
1.0
Carry-over factor = 0.5 for both fixed and pinned end conditions in slope-deflection method.
In matrix stiffness method, the element stiffness matrix for a truss member is derived using:
A
Virtual work principle
B
Unit displacement method
C
Euler-Bernoulli beam theory
D
Plastic hinge concept
Correct Answer:
B. Unit displacement method
Element stiffness matrix is derived by applying unit displacements at nodes and calculating corresponding forces (unit displacement method).
The influence line for a reaction at support A of a simply supported beam AB is:
A
Triangular with ordinate 1 at A
B
Triangular with ordinate 1 at B
C
Linear with maximum ordinate at mid-span
D
Parabolic
Correct Answer:
A. Triangular with ordinate 1 at A
Influence line for reaction at A is triangular, varying from 1 at A to 0 at B, representing the reaction at A due to unit load.
In a two-hinged arch, the number of unknown reactions is:
Two-hinged arch has 2 supports (each with 2 reactions) = 4 unknowns total (horizontal and vertical at each hinge).
What is the recommended curing period for concrete in normal conditions?
A
3 days
B
7 days
C
14 days
D
28 days
Correct Answer:
C. 14 days
IS 456:2000 recommends minimum 14 days of moist curing for normal Portland cement in normal temperature conditions.
What is the effect of adding admixtures like retarders in concrete?
A
Increases early strength
B
Delays setting time
C
Reduces water requirement
D
Increases workability permanently
Correct Answer:
B. Delays setting time
Retarders delay the setting time of concrete, allowing more time for placement and compaction in large structures.
