Deck 13: Structural Members

Question 1

Decide whether each of these statements is True (T) or False
When a uniform cross-section strip is bent into a circular arc:
(i) There is no strain on the neutral axis.
(ii) The stress is a maximum at the outer curved surfaces.

A) (i) T (ii) T
B) (i) T (ii) F
C) (i) F (ii) T
D) (i) F (ii) F

Answer 1

A

Question 2

A beam has a rectangular cross-section 40 mm deep, with second moment of area about the neutral axis of 7 % 104 mm4, and is bent into the arc of a circle. For a bending moment of 120 N m, the maximum bending
Stress is:

A) 17.2 MPa
B) 34.3 MPa
C) 68.6 MPa
D) 1714 MPa

Answer 2

B

Question 3

A tube has an internal diameter of 80 mm and an external diameter of 100 mm. The second moment of area of the section about the neutral axis is:

A) 0.18 x 106 mm4
B) 2.0 x 106 mm4
C) 2.9 x 106 mm4
D) 490 x 106 mm4

Answer 3

C

Question 4

A beam has a section modulus of 2 x 106 mm3. When subject to a bending moment of 12 kN m, the maximum bending stress is:

A) 1.7 MPa
B) 6 MPa
C) 12 MPa
D) 24 MPa

Question 5

A rectangular cross-section beam has a depth four times its breadth. If the maximum bending moment is to be 16 kN m and the maximum bending stress 50 MPa, the limiting depth of the beam is:

A) 49 mm
B) 98 mm
C) 197 mm
D) 394 mm

Question 6

The slenderness ratio for a column with an effective length of 4 m and a radius of gyration of 50 mm is:

A) 0.2
B) 40
C) 80
D) 245