(Solved): Problem 5-8 A beam composed of a W18x40 section (A992 steel) has a configuration that matches Tabl ...

Problem 5-8 A beam composed of a W18x40 section (A992 steel) has a configuration that matches Table 3-23, Case 13, on p.3-212 in the AISC manual. The concentrated load $$\mathrm{P}$$ consists of a dead load of $$9.25$$ kips and a live load of $$6.50$$ kips, and the beam span, $$L$$, is $$32\mathrm{ft}$$. Lateral bracing is provided at both supports and at the load location. (a) Neglecting beam self-weight, using the LRFD approach, and with $$C_b=1$$, is the beam sufficient? (b) Calculate $$C_b$$ for this configuration. (c) If you incorporate the $$C_b$$ value from (b), will a lighter W18×35 (A992) section work? ANSWERS: (a) $$?{\mathrm{M}}_n=130\mathrm{kip}?\mathrm{ft}>{\mathrm{M}}_{\mathrm{u}}=129\mathrm{kip}?\mathrm{ft},\mathrm{OK}$$; (b) $$C_{bL}=1.67,C_{bR}=2.24$$ (c) LEFT: $$?M_n=163$$ kip-ft > $$M_u=108$$ kip-ft, OK; RIGHT: $$?M_n=219$$ kip-ft $$>M_u=129$$ kip-ft, OK