362S162-33 stud column with SFIA service holes — elastic buckling modes

L = 96 in (2438 mm), uniform compression, pinned warping-free ends, braced at midheight (Lx = Ly = Lt = 48 in); 1.5 × 4 in holes at 12, 36, 60, 84 in. Ferrite.jl with QuadShellFiniteElement.jl in the structured flats and TriShellFiniteElement.jl in the patches around the holes. Companion to Moen and Shabhari, ICCFSS 2026.

Reference values: CUFSM gross local 16.14 kN, distortional 37.20 kN; net-section local 24.88 kN; reduced-thickness distortional 35.35 kN; analytical flexural-torsional (KL = 48 in) 37.89 kN.

Drag in a plot to orbit, scroll to zoom, right-drag to pan. Colour = normalized displacement magnitude; deformation scaled to 0.25 × section depth. The Pluto notebook in the repository adds an amplitude slider and a live solve.

Lowest local: P_cr = 15.95 kN (3.59 kips), f_cr = 93.4 MPa (13.55 ksi) — lip half-waves per 48 in: 4 / 4

Local at holes: P_cr = 20.45 kN (4.60 kips), f_cr = 119.8 MPa (17.37 ksi) — lip half-waves per 48 in: 2 / 2

Lowest distortional: P_cr = 36.51 kN (8.21 kips), f_cr = 213.8 MPa (31.01 ksi) — lip half-waves per 48 in: 3 / 3

Global 1: P_cr = 35.25 kN (7.93 kips), f_cr = 206.5 MPa (29.95 ksi) — strong-axis flexure + torsion