section-lookup

name	section-lookup
description	Steel section database lookup — W-shapes, S-shapes, C-channels, L-angles, HSS (rectangular/square/round), pipe sections. Properties: A, I, S, Z, r, J, Cw, dimensions. Cross-references MechEngine sections-db.js (475 sections).

Section Lookup — Complete Skill

Section Database Reference

MechEngine sections database: /Users/mihirpatel/Downloads/MechEngine/shared/sections-db.js Contains 475 sections across 15 types. Always reference this database for exact values.

W-Shapes (Wide Flange) — AISC

Designation: W[depth]x[weight] e.g., W12×26 = 12" nominal depth, 26 lb/ft

Key W-Shape Properties (selected):

Section	A (in²)	d (in)	bf (in)	tf (in)	tw (in)	Ix (in⁴)	Sx (in³)	Zx (in³)	rx (in)	Iy (in⁴)	Sy (in³)	ry (in)	J (in⁴)	Cw (in⁶)
W4×13	3.83	4.16	4.06	0.345	0.280	11.3	5.46	6.28	1.72	3.86	1.90	1.00	0.151	21.3
W6×15	4.43	5.99	5.99	0.260	0.230	29.1	9.72	10.8	2.56	9.67	3.23	1.46	0.101	95.5
W8×31	9.12	8.00	7.995	0.435	0.285	110	27.5	30.4	3.47	37.1	9.27	2.02	0.536	530
W10×33	9.71	9.73	7.960	0.435	0.290	171	35.0	38.8	4.19	36.6	9.20	1.94	0.583	789
W12×26	7.65	12.22	6.490	0.380	0.230	204	33.4	37.2	5.17	17.3	5.34	1.51	0.300	1010
W12×50	14.6	12.19	8.077	0.640	0.370	394	64.7	72.4	5.18	56.3	13.9	1.96	1.82	2160
W14×48	14.1	13.79	8.031	0.595	0.340	485	70.2	78.4	5.85	51.4	12.8	1.91	1.45	2500
W16×50	14.7	16.26	7.073	0.630	0.380	659	81.0	92.0	6.68	37.2	10.5	1.59	1.52	2520
W18×50	14.7	17.99	7.495	0.570	0.355	800	88.9	101	7.38	40.1	10.7	1.65	1.24	3160
W21×57	16.7	21.06	6.555	0.650	0.405	1170	111	129	8.36	30.6	9.35	1.35	1.77	3400
W24×76	22.4	23.92	8.990	0.680	0.440	2100	176	200	9.69	82.5	18.4	1.92	2.68	9430
W30×90	26.3	29.53	10.400	0.610	0.470	3610	245	283	11.7	115	22.1	2.09	3.23	15400
W36×150	44.2	35.85	11.975	0.940	0.625	9040	504	581	14.3	270	45.1	2.47	12.3	54900

S-Shapes (American Standard Beams)

Narrower flanges, steeper slope. Less efficient than W for bending. S8×23: A=6.77in², d=8.00in, Ix=64.9in⁴, Sx=16.2in³ S12×50: A=14.6in², d=12.00in, Ix=305in⁴, Sx=50.8in³

C-Shapes (American Standard Channels)

C designation: C[depth]x[weight] C8×11.5: A=3.37in², d=8.00in, Ix=32.6in⁴, Sx=8.14in³, x̄=0.571in (shear center) C12×20.7: A=6.08in², d=12.00in, Ix=129in⁴, Sx=21.5in³

L-Shapes (Angles)

Equal leg: L4×4×1/2: A=3.75in², Ix=Iy=5.56in⁴, I_z=1.97in⁴, tan(α)=1.000 Unequal leg: L6×4×1/2: A=4.75in², Ix=16.6in⁴, Iy=4.90in⁴

HSS Rectangular/Square (ASTM A500)

HSS[HxBxt]: H=height, B=width, t=wall thickness (actual = 0.93×nominal for welded) HSS6×4×3/8: A=6.18in², Ix=27.5in⁴, Sx=9.17in³, Zx=11.2in³, J=27.9in⁴ HSS8×8×1/2: A=13.5in², Ix=91.8in⁴, Sx=22.9in³, Zx=27.5in³, J=148in⁴

Round HSS (Pipe/Tube)

HSS[OD]x[t]: HSS6.625×0.375: A=7.29in², I=40.5in⁴, S=12.2in³, Z=16.1in³, J=81.0in⁴

Standard Pipe (ASTM A53)

Pipe designation: nominal diameter × schedule Schedule 40 (standard), Schedule 80 (extra strong), Schedule 160, XXS Pipe 4" Sch 40: OD=4.500in, t=0.237in, A=3.17in², I=7.23in⁴, S=3.21in³

SI/Metric Sections

Metric W-shapes: same designation system with mm HEA 200: A=5380mm², Ix=19,200cm⁴, Sx=1910cm³, ry=49.1mm IPE 300: A=5380mm², Ix=8356cm⁴, Sx=557cm³

How to Use Section Database in MechCodex

// In MechEngine/MechCodex, search sections-db.js:
const sections = SECTIONS_DB.filter(s => s.type === 'W' && s.Ix > required_Ix);
sections.sort((a,b) => a.weight - b.weight); // lightest that works
const selected = sections[0];

Section Selection Procedure

1. Calculate required S_x = M_max / σ_allow
2. Calculate required Z_x = M_p / F_y (for plastic design)
3. Filter sections by S_x (or Z_x) ≥ required value
4. Select lightest section (minimum weight/cost)
5. Check d/b ratio (depth/width), flange thickness for compactness
6. Verify r_y for lateral-torsional buckling (need unbraced length L_b)