Bending

Bending occurs when a beam is subjected to transverse loads, causing internal bending moments. The flexure formula σ = M y / I relates bending stress to the applied moment (M), distance from neutral axis (y), and second moment of area (I). The neutral axis is where bending stress is zero. The section modulus Z = I / c is used to determine the maximum stress.

Governing Formulaσ = M y / I, M_max = wL²/8 (UDL), M_max = PL/4 (midspan point load)

Knowledge Check

10 Questions

1.A simply supported beam with a 10 kN point load at midspan has a span of 4 m. What is the maximum bending moment?

2.A rectangular beam has width 100 mm and height 200 mm. What is the second moment of area (I) about the neutral axis?

3.The bending stress at the neutral axis of a beam is:

4.What is the section modulus (Z) for a rectangular section of width b and height h?

5.A 5 m long simply supported beam carries a UDL of 15 kN/m. What is the maximum bending moment?

6.In the flexure formula, what does 'c' represent?

7.Which cross-section shape is most efficient for bending resistance per unit weight?

8.A cantilever beam of length 2 m with a 8 kN point load at the free end. What is the maximum bending moment?

9.The curvature of a beam under bending is proportional to:

10.If the depth of a rectangular beam is doubled, by what factor does the section modulus increase?