What is the section modulus of W18X119?

Sx = 231 inÃÂÃÂ³, Zx = 262 inÃÂÃÂ³.

What steel grade is standard for W18X119?

ASTM A992 (Fy = 50 ksi, Fu = 65 ksi) for W-shapes.

What is the moment of inertia of W18X119?

Ix = 2190 inÃÂ¢ÃÂÃÂ´, Iy = 253 inÃÂ¢ÃÂÃÂ´.

W18X119 Steel Beam — Section Properties

Dimensions

Property	Value	Unit
Depth (d)	19	in (482.6 mm)
Flange Width (bf)	11.30	in (287.0 mm)
Flange Thickness (tf)	1.06	in
Web Thickness (tw)	0.66	in
Area (A)	35.10	inÃÂÃÂÃÂÃÂ² (226.5 cmÃÂÃÂÃÂÃÂ²)
Weight	119	lb/ft (177 kg/m)

Elastic Section Properties

Property	Strong Axis (X-X)	Weak Axis (Y-Y)	Unit
Moment of Inertia (I)	2,190	253	inÃÂÃÂ¢ÃÂÃÂÃÂÃÂ´
Elastic Section Modulus (S)	231	44.90	inÃÂÃÂÃÂÃÂ³
Plastic Section Modulus (Z)	262	69.10	inÃÂÃÂÃÂÃÂ³
Radius of Gyration (r)	7.90	2.69	in

Torsional Properties

Property	Value	Unit
Torsional Constant (J)	10.60	inÃÂÃÂ¢ÃÂÃÂÃÂÃÂ´
Warping Constant (Cw)	20,300	inÃÂÃÂ¢ÃÂÃÂÃÂÃÂ¶
Distance Between Flange Centroids (ho)	17.90	in
Effective Radius (rts)	3.13	in

Section Profile Summary

With Ix = 2,190 in⁴, this wide flange is suitable for long-span floor beams and transfer girders where stiffness controls the design.

At 19" deep and 119 lb/ft, this is a mid-range section suitable for floor beams, roof framing, and columns in low-to-mid-rise structures.

Key Design Checks (AISC 360)

Check	Formula	This Section
Plastic moment	Mp = Zx × Fy	13,100 kip-in
Deflection	Δ = 5wLÃÂ¢ÃÂÃÂ´/(384EIx)	Use Ix = 2,190 in⁴
Torsion	St. Venant = GJ/L	J = 10.6 in⁴
Column buckling	KL/r ÃÂ¢ÃÂÃÂ Fcr	r_x = 7.9 in

Design Notes

Compactness: Most W-shapes in ASTM A992 satisfy the compact limits in AISC 360 Table B4.1b for flexure (ÃÂÃÂ» ÃÂ¢ÃÂÃÂ¤ ÃÂÃÂ»p). This allows full plastic moment Mp development before local buckling occurs.
Flange local buckling (FLB): The flange slenderness ratio bf/2tf is compared against ÃÂÃÂ»pf = 0.38ÃÂ¢ÃÂÃÂ(E/Fy) ÃÂ¢ÃÂÃÂ 9.15 for compact sections.
Web local buckling (WLB): h/tw is checked against ÃÂÃÂ»pw = 3.76ÃÂ¢ÃÂÃÂ(E/Fy) ÃÂ¢ÃÂÃÂ 90.5 for flexure, and a more restrictive limit for uniform compression.
Lateral-torsional buckling (LTB): Lp ÃÂ¢ÃÂÃÂ 114.0 in (plastic limit). For unbraced lengths ÃÂ¢ÃÂÃÂ¤ Lp, the full plastic moment is available. Between Lp and Lr, linear interpolation per AISC 360 Eq. F2-2 applies.

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: Assembly hall floor beam — w18x119

Scenario: Public assembly space — higher live load for movable seating/standing. Simply supported wide flange, 46 ft span, 8 ft tributary width. Service loads: 60 psf dead + 100 psf live (1280 plf total).

Given:

Span L = 46 ft (552 in)
Total service load w = 1280 plf
Live load portion w_L = 800 plf
Section w18x119: Ix = 2,190 in⁴, Sx = 231 in³, Zx = 262 in³
Steel: ASTM A992, Fy = 50 ksi, E = 29,000 ksi
Design moment strength: φMn = 0.9 × Zx × Fy = 983 kip-ft

Step 1 — Live load deflection check:

Δ_LL = 5 w_L LÃÂ¢ÃÂÃÂ´ / (384 E Ix)

Δ_LL = 5 × (800/12) × (552)ÃÂ¢ÃÂÃÂ´ / (384 × 29,000,000 × 2,190)

Δ_LL = 1.27 in

Step 2 — Allowable deflection (IBC Table 1604.3, L/240):

Δ_allow = L / 240 = 552 / 240 = 2.30 in

Step 3 — Dead + live deflection:

Δ_total = 2.03 in

Step 4 — Design check:

ÃÂ¢ÃÂÃÂ Live load deflection is within the L/240 limit.

The required flexural strength at ultimate is approximately w_u LÃÂÃÂ²/8. With factored loads 1.2D + 1.6L, verify φMn = 983 kip-ft is adequate per AISC 360 Chapter F. Also check shear capacity (φVn = 0.6 Fy Aw × 0.9) and bearing at supports.

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.