What is the section modulus of L5X5X7/16?

Sx = 2.78 inÃÂÃÂ³, Zx = 5 inÃÂÃÂ³ (strong axis). Sy = 2.78 inÃÂÃÂ³, Zy = 5 inÃÂÃÂ³ (weak axis).

What steel grade is standard for L5X5X7/16?

ASTM A36 (Fy = 36 ksi) for angles. Verify with mill certificate.

What is the moment of inertia of L5X5X7/16?

Ix = 10 inÃÂ¢ÃÂÃÂ´ about the strong axis and Iy = 10 inÃÂ¢ÃÂÃÂ´ about the weak axis. The radius of gyration is rx = 1.54 in and ry = 1.54 in.

L5X5X7/16 Steel Angle — Section Properties

Dimensions

Property	Value	Unit
Leg Length (leg)	5	12.70 cm
Leg Thickness (t)	0.438	1.11 cm
Area (A)	4.22 in²	27.2 cmÃÂÃÂ²
Weight	14.3 lb/ft	21.3 kg/m

Elastic Section Properties

Property	Strong Axis (X-X)	Weak Axis (Y-Y)	Unit
Moment of Inertia (I)	10	10	in⁴
Elastic Section Modulus (S)	2.78	2.78	in³
Plastic Section Modulus (Z)	5	5	in³
Radius of Gyration (r)	1.54	1.54	in

Torsional Properties

Property	Value	Unit
Torsional Constant (J)	0.284	in⁴
Warping Constant (Cw)	0.508	in⁶

Section Profile Summary

Leg local buckling (b/t ratio) and shear lag at bolted connections are the governing limit states for this angle in tension applications. Per AISC 360 Section D3, the effective net area accounts for the eccentricity when connected through one leg only.

Key Design Checks (AISC 360)

Check	Formula	This Section
Plastic moment	Mp = Zx × Fy	250 kip-in
Deflection	Δ = 5wLÃÂ¢ÃÂÃÂ´/(384EIx)	Use Ix = 10 in⁴
Torsion	St. Venant = GJ/L	J = 0.284 in⁴
Column buckling	KL/r ÃÂ¢ÃÂÃÂ Fcr	r_x = 1.54 in

Design Notes

Single-angle flexure: Use AISC 360 Section F10. Moments are resolved about the principal axes (w-w and z-z), not the geometric axes. The geometric properties above are tabulated for convenience — transform to principal axes for accurate flexure design.
Leg slenderness: The outstanding leg b/t ratio controls compactness per AISC 360 Table B4.1a, Case 6 (single angle).
Shear lag in bolted connections: When only one leg is connected, the effective net area per AISC 360 Section D3 accounts for the eccentricity. For welded connections, U depends on the weld length-to-width ratio.

Verification (AISC 360): All designs using this section must be verified by a licensed Professional Engineer. Before finalizing member selection, check beam-column interaction (P-M), lateral-torsional buckling, serviceability deflections, and all connection limit states. See Engineering Disclaimer.

Worked Example: Tension Member Check — l5x5x7-16

Scenario: A single angle used as a diagonal tension brace in a braced frame bay. The brace is connected to a gusset plate by welding one leg. Because the connection is eccentric (load applied to one leg only), shear lag reduces the effective net area.

Given:

l5x5x7-16: gross area Ag = 4.22 in²
Steel: Fy = 50 ksi, Fu = 65 ksi
Connection: welded to one leg only

Step 1 — Gross section yield (AISC 360 Eq. D2-1):

φTn_yield = φ × Ag × Fy = 0.9 × 4.22 × 50 = 190 kips

Step 2 — Net section fracture with shear lag (AISC 360 Eq. D2-2):

For a single angle welded to one leg, the shear lag factor U depends on the connection length and eccentricity. Per AISC 360 Table D3.1, for a single angle with 4+ fasteners per line or equivalent weld length, U = 0.80.

Ae = U × An where An = Ag (no bolt holes for welded connection)

φTn_fracture = φ × Ae × Fu = 0.75 × (0.80 × 4.22) × 65 ÃÂ¢ÃÂÃÂ 138 kips

Step 3 — Design check:

The smaller of the two limit states governs: φTn = min(yield, fracture) kips. Ensure the factored axial demand (from wind or seismic load combinations) does not exceed this value. Also verify the gusset plate weld length develops the required force.

Related Resources

Design Resources

Section Properties Lookup — Compare with similar sections
Steel Beam Sizes Reference — Standard beam dimensions

Educational reference only. Verify all section properties against the current AISC 360 Manual and mill certificates before design. Results are PRELIMINARY — NOT FOR CONSTRUCTION.