Beer & Johnston — Pure Bending: Problem 4.129

4.127 through 4.134 The couple \( \mathbf{M} \) is applied to a beam of the cross section shown in a plane forming an angle \( \beta \) with the vertical. Determine the stress at (a) point \( A \), (b) point \( B \), (c) point \( D \). Problem 4.129: The cross section is an I-shape with the following dimensions: Total height \( h = 80\text{ mm} + 80\text{ mm} = 160\text{ mm} \). Flange width \( b = 30\text{ mm} + 30\text{ mm} = 60\text{ mm} \). Flange thickness \( t_f = 20\text{ mm} \). Web thickness \( t_w = 20\text{ mm} \) (assumed to match flange thickness as typical for such problems). Bending moment \( M = 25\text{ kN}\cdot\text{m} \) at an angle \( \beta = 15^\circ \) with the vertical plane.