断面图形 A:断面積(cm2)e:到图心得距离(cm) I:断面二次力矩(c m4)ﻫZ:断面系数(cm 3) → I/ei:断面二次半径(cm) → √(I/A)正方形 ﻫA = a2 e = a/2 I = a4 /1 2 Z = a 3 /6 i = a / √12 = 0、2 8 867a 正方形 ﻫﻫA = a2 e = a / √2 I = a4 /12 Z = a3 / ( 6√2 )i = a / √12 = 0、28867a长方形 ﻫA = bh e = h / 2 I = bh3 /1 2 Z = bh2 /6 i = h / √1 2 = 0、28867h 長方形 斜着 AﻫﻫA = b h e = b h / √( b2 + h2 )I = b3 h3 / ( 6 ( b 2 + h2 ) ) Z = b2 h2 / ( 6 √( b2 + h2 ) ) i = b h / √( 6 ( b 2 + h2 ) ) 長方形 斜着BﻫA = b h e = ( h・co s θ + b・s inθ) / 2I = b h ( h 2・c os2θ + b 2・sin2θ) / 12Z = b h ( h2・c os2θ + b2・sin 2θ) / ( 6 ( h・c osθ + b・sinθ ) )i = √( ( h 2・cos2θ + b2・s i n2θ) / 12 ) 正-角管状A = a2 - a12 e = a / 2 I = ( a4 - a 14 ) / 1 2 Z =( a4 - a14 ) / ( 6a ) i = √( ( a 2 + a1 2 ) /12 ) 長-角管状ﻫA = bh - b1h 1 e = h / 2 I = ( b h3 - b 1h13 ) / 12 Z = ( bh 3 - b1h 1 3 ) / ( 6