HP18X181 Steel HP-shape — Section Properties
Dimensions
| Property | Value | Unit |
|---|---|---|
| Depth (d) | 18 | 457.2 mm |
| Flange Width (bf) | 18 | 45.72 cm |
| Flange Thickness (tf) | 1 | 25.4 mm |
| Web Thickness (tw) | 1 | 25.4 mm |
| Area (A) | 53.2 in² | 343.2 cmÃÂò |
| Weight | 181 lb/ft | 269.4 kg/m |
Elastic Section Properties
| Property | Strong Axis (X-X) | Weak Axis (Y-Y) | Unit |
|---|---|---|---|
| Moment of Inertia (I) | 3020 | 974 | in⁴ |
| Elastic Section Modulus (S) | 336 | 108 | in³ |
| Plastic Section Modulus (Z) | 379 | 167 | in³ |
| Radius of Gyration (r) | 7.53 | 4.28 | in |
Torsional Properties
| Property | Value | Unit |
|---|---|---|
| Torsional Constant (J) | 20.7 | in⁴ |
| Warping Constant (Cw) | 70400 | in⁶ |
| Distance Between Flange Centroids (ho) | 17 | in |
| Effective Radius (rts) | 4.96 | in |
Section Profile Summary
This is a standard hot-rolled bearing pile profile covered by AISC 360. The tabulated section properties are computed from the nominal dimensions per the governing material standard. With Ix = 3,020 in⁴, the strong-axis flexural stiffness is suitable for preliminary sizing of beams and beam-columns.
At 18" deep and 181 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 | 18,950 kip-in |
| Deflection | Δ = 5wLâÃÂô/(384EIx) | Use Ix = 3,020 in⁴ |
| Torsion | St. Venant = GJ/L | J = 20.7 in⁴ |
| Column buckling | KL/r âÃÂàFcr | r_x = 7.53 in |
Design Notes
- Compactness: Verify flange and web slenderness against AISC 360 Table B4.1 classification limits for the governing load case (pure compression, pure flexure, or combined).
- Combined loading: For members under simultaneous axial force and bending, use the interaction equations in AISC 360 Section H. The governing equation depends on the ratio of required to available axial strength.
- Connection limit states: Check bolt bearing, tear-out, block shear, and weld strength at all connections. The governing connection limit state often controls the member size selection.
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: Bearing Pile Capacity — hp18x181
Scenario: hp18x181 driven to 60 ft depth in medium-dense sand. The pile carries axial compression from a column above. Pile capacity is governed by a combination of geotechnical end bearing + skin friction, plus the structural section capacity.
Given:
- hp18x181: Ag = 53.2 in²
- Steel: ASTM A572 Gr. 50, Fy = 50 ksi
- Unbraced length below ground: L = 60 ft (fully laterally supported by soil)
Structural capacity (AISC 360 Chapter E):
φPn = 0.9 × Fy × Ag = 0.9 × 50 × 53.2 = 2,394 kips
The structural capacity typically governs over geotechnical capacity for HP sections in dense soils. Driving stresses should also be checked per PDCA/AASHTO specifications — limit driving stress to 0.9Fy during hard driving conditions.
The final pile capacity must be confirmed by a geotechnical engineer based on site-specific soil conditions, PDA testing, and pile driving records. The structural capacity above is a preliminary estimate only.
Related Resources
- Steel Beam Capacity Calculator
- Column Capacity Calculator
- Beam Deflection Calculator
- Section Properties Calculator
- Steel Grades Reference
- Section Comparison Tool
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.