Steel Buildings in Europe

Title Appendix A Worked Example: Wind action on a multi-storey building 11 of 18 3 - 32 9,89 23,8 3,1 75,9 ( ) ( ) ( , ) m s s 1,x L s 1,x     v z n L z f z n Then:   0,0302 9,89 1 10,2 6,8 9,89 ( , ) 5 / 3 L      S z n 12 Logarithmic decrement of structural damping  s = 0,05 13 Logarithmic decrement of aerodynamic damping  a  = 1,25 kg/m 3 c f = c f,0 = 0,9 for d/b = 120/10 = 12 m e is the equivalent mass per unit length: m e = 150 t/m Therefore:  a = 0,0003 2 3,1 150.10 0,9 1,25 10 23,8 3       EN 1991-1-4 § F.5(4) 14 Logarithmic decrement of damping due to special devices  d = 0 (no special device) 15 Logarithmic decrement  =  s +  a +  d = 0,05 + 0,0003 + 0 = 0,0503 EN 1991-1-4 § F.5(1) 16 Aerodynamic admittance functions Function R h :   9,89 21,0 75,9 4,6 35 , ( ) 4,6 L s 1,x s h      f z n L z h  Then, we obtain: R h (  h ) = 0,0465 EN 1991-1-4 § B.2(6) Function R b :   9,89 5,99 75,9 4,6 10 , ( ) 4,6 L s 1,x s b      f z n L z b  Then, we obtain: R b (  b ) = 0,153 17 Resonance response factor 2 R =  2 × 0,0302 × 0,0465 × 0,153 / (2 × 0,0503) = 0,0211 EN 1991-1-4 § B.2(6)