Question

Steel design course

I need question number 9-4

306 Chapter 9 esignor u 9.11 PROBLEMS FOR SOLUTION 9-1 to 9-10. Using both LRFD and ASD, select the most economical sections, with F-S0 unless otherwise specified, nd assuming full literal bracing for the compresa langes. Working or service loads are given for each case, and beam self-weighe not included 9-1" (Ans. W30 x 90 LRFD and ASD) D-1.20 k/ft L-300 k/ft 36 ft -l FIGURE P9-1 9-2 P- P- 25 k -10 ft 10 ft FIGURE P9-2 9-3, Repeat Prob. 9.2, using P 9-4 36k. (Ans W27 x 84 LRFD and ASD) P. 24 k 0.5PL- 12k Wp=1.5 kft 8 ft 16 ft FIGURE P94 (Ans. W30 x 116 LRFD, W33 x 118 ASD) WD- 20k/ft 9-5. PL 15k PL=15 k 8 ft 24 ft FIGURE P9-5

Answer 1

Given beam has is a cantilver beam. Therefore, maximum moment in beam will be at fixed end

moment at fixed end of beam due to dead load = 1.5*16*16/2=192 kip-ft

moment at fixed end due to live load = 24*8 + 12*16=384 kip-ft

Total ASD level moment in beam = 192+384=576 kip-ft

total LRFD level moment in beam = 1.2*192 + 1.6*384=844.8 kip-ft

lightest beam section that has bending capacity greater than 576 kip-ft per ASD is W27x84

lightest beam section that has bending capacity greater than 844.8 kip-ft per LRFD is W27x84

Therefore, correct answer is W27x84