Determine the moment of resistance:
A rectangular beam of size 40 mm × 60 mm is subjected to bending. The maximum bending stress is restricted to 75 N/mm2. Determine the moment of resistance of the beam section.
Solution
Section modulus, Z = (1 /6)bd 2
= (1/6) × 40 × (60)2 = 24 × 103 mm3
Moment of resistance, M = σ × Z
= 75 × 24 × 103
= 1800 × 103 N mm = 1.8 kN m
Thus, moment of resistance of the beam section = 1.8 kN m.