A built-up steel beam of I-section with channels attached to the flanges (see figure part a) is simply supported at the ends. Two equal and oppositely directed bending moments M0 act at the ends of the beam, so that the beam is in pure bending. The moments act in plane mm, which is oriented at an angle α to the xy plane.
(a) Determine the orientation of the neutral axis and calculate the maximum tensile stress σmax due to the moments M0.
(b) Repeat part a if the channels are now with their flanges pointing away from the beam flange, as shown in figure part b. Data for the beam are as follows: S 6 ×12.5 section with C 4 × 5.4 sections attached to the flanges, M0= 45 k-in., and α = 40°. (Note: See Tables E-2a and E-3a of Appendix E for the dimensions and properties of the S and C shapes.)
