BRIDGES: FOUNDATIONS OF ENGINEERING 150 Comprehensive Questions &
Answers
SECTION 1: FUNDAMENTAL CONCEPTS & BRIDGE TYPES
Question 1 (Multiple Choice):
Which of the following is the oldest known type of bridge?
A. Suspension bridge
B. Arch bridge
C. Beam bridge
D. Cable-stayed bridge
Answer: C (Beam bridge)
Rationale: The beam bridge is the simplest and oldest form of bridge, essentially a log
across a stream or a stone slab across a gap. Early humans created beam bridges by
placing tree trunks or stone slabs across natural obstacles.
Question 2 (Multiple Choice):
In a simply supported beam bridge, the maximum bending moment occurs at:
A. The supports
B. The quarter-span points
C. The mid-span
D. The neutral axis
,Answer: C (The mid-span)
Rationale: For a simply supported beam with uniform loading, the bending moment
diagram is parabolic with the maximum value at the center of the span. The shear force is
maximum at the supports and zero at mid-span.
Question 3 (Multiple Choice):
What is the primary force that an arch bridge transfers to its abutments?
A. Tension
B. Shear
C. Compression
D. Torsion
Answer: C (Compression)
Rationale: Arch bridges work primarily in compression. The curved shape transfers vertical
loads into horizontal thrust at the abutments, allowing the arch to carry loads through
compressive forces throughout its structure.
Question 4 (Multiple Choice):
Which bridge type uses cables that run directly from the tower to the deck in a fan-like
pattern?
,A. Suspension bridge
B. Cable-stayed bridge
C. Truss bridge
D. Cantilever bridge
Answer: B (Cable-stayed bridge)
Rationale: In cable-stayed bridges, cables connect the deck directly to one or more towers
in a fan, harp, or semi-fan configuration. Unlike suspension bridges, there is no main
catenary cable.
Question 5 (Multiple Choice):
The main cable of a suspension bridge is under which type of primary stress?
A. Compression
B. Tension
C. Bending
D. Buckling
Answer: B (Tension)
Rationale: The main cables of a suspension bridge carry the deck load in pure tension. The
shape of the cable (catenary or parabolic) is determined by the tension forces distributing
the load to the towers and anchorages.
, Question 6 (Multiple Choice):
What structural element distinguishes a truss bridge from a simple beam bridge?
A. Use of piers
B. Triangular framework of connected elements
C. Curved arch shape
D. Suspension cables
Answer: B (Triangular framework of connected elements)
Rationale: A truss bridge uses a triangulated framework of straight members connected at
joints (nodes). The triangle is inherently stable geometrically, allowing truss members to
carry primarily axial loads (tension or compression).
Question 7 (Multiple Choice):
In a Pratt truss, which members are in tension under typical loading?
A. Vertical members
B. Diagonal members sloping toward the center (at the ends)
C. Diagonal members sloping toward the supports (at the ends)
D. Top chord members
Answer: B (Diagonal members sloping toward the center)
Rationale: In a Pratt truss, the diagonal members slope toward the center of the span.
Under typical loading, these diagonal members experience tension, while the vertical
members are in compression. The top chord is in compression, and the bottom chord is in
tension.
Answers
SECTION 1: FUNDAMENTAL CONCEPTS & BRIDGE TYPES
Question 1 (Multiple Choice):
Which of the following is the oldest known type of bridge?
A. Suspension bridge
B. Arch bridge
C. Beam bridge
D. Cable-stayed bridge
Answer: C (Beam bridge)
Rationale: The beam bridge is the simplest and oldest form of bridge, essentially a log
across a stream or a stone slab across a gap. Early humans created beam bridges by
placing tree trunks or stone slabs across natural obstacles.
Question 2 (Multiple Choice):
In a simply supported beam bridge, the maximum bending moment occurs at:
A. The supports
B. The quarter-span points
C. The mid-span
D. The neutral axis
,Answer: C (The mid-span)
Rationale: For a simply supported beam with uniform loading, the bending moment
diagram is parabolic with the maximum value at the center of the span. The shear force is
maximum at the supports and zero at mid-span.
Question 3 (Multiple Choice):
What is the primary force that an arch bridge transfers to its abutments?
A. Tension
B. Shear
C. Compression
D. Torsion
Answer: C (Compression)
Rationale: Arch bridges work primarily in compression. The curved shape transfers vertical
loads into horizontal thrust at the abutments, allowing the arch to carry loads through
compressive forces throughout its structure.
Question 4 (Multiple Choice):
Which bridge type uses cables that run directly from the tower to the deck in a fan-like
pattern?
,A. Suspension bridge
B. Cable-stayed bridge
C. Truss bridge
D. Cantilever bridge
Answer: B (Cable-stayed bridge)
Rationale: In cable-stayed bridges, cables connect the deck directly to one or more towers
in a fan, harp, or semi-fan configuration. Unlike suspension bridges, there is no main
catenary cable.
Question 5 (Multiple Choice):
The main cable of a suspension bridge is under which type of primary stress?
A. Compression
B. Tension
C. Bending
D. Buckling
Answer: B (Tension)
Rationale: The main cables of a suspension bridge carry the deck load in pure tension. The
shape of the cable (catenary or parabolic) is determined by the tension forces distributing
the load to the towers and anchorages.
, Question 6 (Multiple Choice):
What structural element distinguishes a truss bridge from a simple beam bridge?
A. Use of piers
B. Triangular framework of connected elements
C. Curved arch shape
D. Suspension cables
Answer: B (Triangular framework of connected elements)
Rationale: A truss bridge uses a triangulated framework of straight members connected at
joints (nodes). The triangle is inherently stable geometrically, allowing truss members to
carry primarily axial loads (tension or compression).
Question 7 (Multiple Choice):
In a Pratt truss, which members are in tension under typical loading?
A. Vertical members
B. Diagonal members sloping toward the center (at the ends)
C. Diagonal members sloping toward the supports (at the ends)
D. Top chord members
Answer: B (Diagonal members sloping toward the center)
Rationale: In a Pratt truss, the diagonal members slope toward the center of the span.
Under typical loading, these diagonal members experience tension, while the vertical
members are in compression. The top chord is in compression, and the bottom chord is in
tension.
