Steel Buildings in Europe

Part 4: Detailed Design of Portal Frames 4 - 19 A summary of the assessment of sensitivity to second order effects and the amplification to allow for second order effects is given in Table 3.1. Table 3.1 Second order effects: assessment and amplification factors Restrictions Elastic analysis Plastic analysis shallow slopes, and rafter axial force not significant  cr  cr Measure of sensitivity to second order effects steep slopes, and rafter axial force significant  cr,est  cr,est Regular frames        cr 1 1 1  or          est cr, 1 1 1         cr 1 1 1  or          est cr, 1 1 1  Amplifier to allow for second order effects Irregular frames, but excluding tied portals        cr 1 1 1  or          est cr, 1 1 1          cr , 1 1 11 or          est cr, 1 1 1,1  Amplifier applied to: Horizontal loads only All loads