(Solved): (30 points) Determine the LRFD design strength \( \phi \mathrm{cPn} \) and the ASD allowable streng ...

(30 points) Determine the LRFD design strength \( \phi \mathrm{cPn} \) and the ASD allowable strength \( \mathrm{Pn} / \Omega \mathrm{c} \) for a W12x87 (ASTM A992) column with \( \mathrm{L}=20 \mathrm{ft} \). and fixed supports at top and bottom. Make sure you include units in all your final answers. (a) First determine whether the section is "slender" or "nonslender" by calculations. (b) Calculate the LRFD/ASD strengths using the equations of AISC Section E3. (c) Using the critical stress values in Table 4-22 of the AISC Manual, determine the LRFD/ASD strengths and compare with part (b). (d) Repeat the problem using Table 4-1 of the AISC Manual and compare with parts (b) and (c).