Name Student ID No 12 Select the lightest available W12 sect

Name: Student ID No.:- 12. Select the lightest available W12 section to support the axial loads Po 220 k and Pt. 280k if KL 14 ft and F, 50 ksi. Check for limiting width/ thickness ratios for both flange and web according to uniform compression in flanges and webs of doubly symmetric I-shaped sections for noncompact sections from Table B4.1. Flanges: tLs0.561 (Note: in Table B4 . 1 , b is used instead and, thus, b=br/2) Webs: h (Note: h d-2k) - 1.49 ratios may be calculated or obtained from Table 1-1,

Solution

P_D=220 Kips

P_L=280 kips

design load = 1.2*220 + 1.6*280=712 kips

effective length =14 ft

the lightest W12 section that has capapcity greater than 712 kips for effective length of 14 ft is W12x72 that has a axial compression capapcity of 759 kips

bf=12.04 in

tf=0.67 in

bf/2*tf=12.04/(2*0.67)=8.985

0.56*sqrt(E/fy) = 0.56*sqrt(29000/50)=13.49

8.985<13.49

h=9.125 in

t_w=0.43

h/t_w=9.125/0.43=21.22

1.49*sqrt(E/fy)=1.49*sqrt(29000/50)=35.88

21.22 < 35.88

Therefore, section is compact