Steel Buildings in Europe

Title APPENDIX D Worked Example: Design of portal frame using elastic analysis 30 of 44 4 - 111  = 298 111 = 0,37  1 C = 1,42 Appendix C of this document L m =   2 4 3 2 2 3 235 355 66,9 10 9880 10 1702 756 1, 42 1 9880 127 10 57 , 4 1 38 41, 2                    L m = 1669 mm Purlin spacing is 1700 mm > 1669 mm Therefore the normal design procedure must be adopted and advantage may not be taken of the restraints to the tension flange. Flexural buckling resistance about the minor axis, N b,z,Rd As previously:  Curve b for hot rolled I sections   z  0,34 EN 1993-1-1 Table 6.2 Table 6.1  1 = y f E  = 355 210000  = 76,4 EN 1993-1-1 §6.3.1.3 z  = z 1 cr 1  i L = 76, 4 1 41, 2 2930  = 0,931  z =     2 z z z 0, 2 0,5 1        z =     2 0,5 1 0,34 0,931 0, 2 0,931    = 1,06 EN 1993-1-1 §6.3.1.2  z = 2 z 2 z z 1      = 2 2 1, 06 1, 06 0,931 1   = 0,638 N b,z,Rd = M1 z y   Af = 3 10 1, 0 355 9880 0,638     = 2238 kN N Ed = 127 kN < 2238 kN OK Lateral-torsional buckling resistance, M b,Rd As previously the C 1 factor needs to be calculated in order to determine the critical moment of the member. For simplicity, the bending moment diagram is considered as linear, which is slightly conservative.  = 298 0 = 0  1 C = 1,77 Appendix C of this document