A C 200 x 17.1 channel sections has an angle with equal legs attached as shown; the angle serves as a lintel beam. The combined steel section is subjected to a bending moment M having its vector directed along the z axis, as shown in the figure. The centroid C of the combined section is located at distances xc and yc from the centroid (C1) of the channel alone. Principal axes x1 and y1 are also shown in the figure and properties Ix1, Iy1 and θp are given below.
Find the orientation of the neutral axis and calculate the maximum tensile stress σt and maximum compressive stress σc if the angle is an L 76 x 76 x 6.4 section and M = 3.5 kN m. Use the following properties for principal axes for the combined section: Ix1 = 18.49 x 106 mm4 Iy1 = 1.602 x 106 mm4, θp 7.448° (CW), xc = 10.70 mm, yc = 24.07 mm.

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yI L76 x 76x 6.4 lintel C 200 x 17.1