钢筋段计算器

� Hollow RHS Section: Outer $B\times H$, Inner $b=B-2t$, $h=H-2t$.Ix = (B�H� - b�h�) � 12 | Iy = (H�B� - h�b�) � 12

� I-Beam Section: Flange $B$, Web thickness $tw$, total height $H$, flange thickness $tf$, inside height $h=H-2tf$.Ix = [B�H� - (B - tw)�h�] � 12 | Iy = (2�tf�B� + h�tw�) � 12

� C-Channel Section: Flange B, Web thickness tw, total height H, flange thickness tf. Centroid offset X_cg is computed relative to back of web, and Y-axis Inertia is calculated using the Parallel Axis Theorem:Iy = [h�tw�/12 + h�tw(X_cg - tw/2)�] + 2[tf�B�/12 + B�tf(X_cg - B/2)�]

� Other properties: Modulus S = I � y_max, Gyration r = v(I � A). All units are expressed in standard metric format: Area in mm�, Inertia in mm4 (and scaled to cm4 for engineering usability), Section Modulus in cm�, Radius of Gyration in mm.