Don’t do the extra credit. Just the regular problem.
The single-story unbraced frame shown below is subjected to dead load, roof live load, and wind load Figure I shows the results of a first-order analysis selative to the columns of the frame The axial load and end moment (also equal to the maximum moment in the column) are given separately for the diffierent load cases (i e, dead load, roof live load, and lateral wind load) All vertical loads are symmetrically placed and contribute only to the Mar moments (ie, the frame behaves as a braced frame when only vertical loads are applied) The lateral load produces Mo moments Use A992 steel and select a W14 shape for the celumes Bending shown in the figures is about the strong axis. Assume K,1 for both braced and unbraced conditions K1 for the braced conditions, and K2 for the unbraced conditions. Each column is laterally braced at the top and at the bottiom (ie, -18 t) Use the second-order axial foeces and moments based on the moment amplification method. Assume S l and B: 1.14. Use LRFD (50 points. Points will be given as follows a) P. and M. from the controlling load combination(with scparate vallacs for P M P and M including second-order effects: 15 points b) Trial section 10 peints c) Selection of an appeopeiate cross-section satisfying AISC specifications with an interaction coefficient obtained from Equations HI-laH-lb of the Sieel Manual 2 08 25 points EX TIRA CREDIT “l: Calculate the amplification coefficserts B·and 8; for desgned bean-column by assuming a drift index Δ11-1/400 based on the service wind load (ie, H. 36 kps) Use the efetve kength method and compule the amplification coefficient Bi using EP-El Calculate B by assuming that ay-2P and RM-0.85. (10 extra credit peints) EXTRA CREDIT #2: Check if the selected column is also the most efficent among the W 14 sections ( 10 extra credit peints) 0.860n 145 P 19 M-79na P-33 M-130a 18 Dead load Rool live load P. 1.4厥 M-32ha