Steel Buildings in Europe

Title APPENDIX D Worked Example: Design of portal frame using elastic analysis 12 of 44 4 - 93 7.4.2. Compression resistance N c,Rd = M0 y  A f = 3 10 1, 0 355 11600    = 4118 kN N Ed = 168 kN  N c,Rd = 4118 kN OK EN 1993-1-1 §6.2.4 Bending and axial force interaction When axial force and bending moment act simultaneously on a cross-section, the axial force can be ignored provided the following two conditions are satisfied: N Ed  0,25 N pl,Rd and N Ed  M0 w w y 0,5  h t f 0,25 N pl,Rd = 0,25  4118 = 1030 kN 3 M0 w w y 10 1, 0 0,5 468 10, 2 355 0,5        h t f = 847 kN 168 kN < 1030 kN and 847 kN, OK Therefore the effect of the axial force on the moment resistance may be neglected. EN 1993-1-1 §6.2.9 Bending moment resistance EN 1993-1-1 §6.2.5 M pl,y,Rd = M0 pl y  W f = 6 3 10 1, 0 355 10 2194     = 779 kNm M y,Ed = 616 kNm < 779 kNm OK 7.5. Out-of-plane buckling The out-of-plane buckling interaction is verified with expression (6.62) in EN 1993–1–1. 1, 0 b,Rd y,Ed zy b,z,Rd Ed   M M k N N This expression should be verified between torsional restraints. If the tension flange is restrained at discreet points between the torsional restraints and the spacing between the restraints to the tension flange is small enough, advantage may be taken of this situation. In order to determine whether or not the spacing between restraints is small enough, Annex BB of EN 1993-1-1 provides an expression to calculate the maximum spacing. If the actual spacing between restraints is smaller than this calculated value, then the methods given in Appendix C of this document may be used to calculate the elastic critical force and the critical moment of the section.