Table I1.1b: Limiting Width-to-Thickness Ratios for Compression Steel Elements in Composite Members Subjected to Flexure for Use with Section I3.4
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| Description of Element | Width-to- Thickness Ratio | λp Compact Composite/ Noncompact Composite | λr Noncompact Composite/ Slender- Element Composite | Maximum Permitted |
|---|---|---|---|---|
| Flanges of rectangular HSS and box sections of uniform thickness | b/t | 2.26 √E / Fy | 3.00 √E / Fy | 5.00 √E / Fy |
| Webs of rectangular HSS and box sections of uniform thickness | h/t | 3.00 √E / Fy | 5.70 √E / Fy | 5.70 √E / Fy |
| Round HSS | D/t | 0.09E / Fy | 0.31E / Fy | 0.31E / Fy |
exceeds , but does not exceed from Table II.1b, the section is noncompact composite. If the width-to-thickness ratio of any steel element exceeds , the section is slender-element composite. The maximum permitted width-to-thickness ratio shall be as specified in Table II.1b.
Refer to Section B4.1b for definitions of width, and , and thickness, , for rectangular and round HSS sections and box sections of uniform thickness.
User Note: All current ASTM A500/A500M Grade C square HSS sections are compact composite according to the limits of Table II.1a and Table II.1b, except HSS7x7x1/8, HSS8x8x1/8, HSS10x10x3/16, HSS12x12x3/16, HSS14x14x1/4, HSS16x16x1/4, HSS18x18x5/16, and HSS20x20x5/16, which are noncompact composite for both axial compression and flexure, and HSS9x9x1/8 and HSS18x18x1/4, which are slender-element composite for both axial compression and flexure.
All current ASTM A1085/A1085M square HSS are compact composite except for HSS8×8×1/8, HSS 9×9×1/8, HSS 12×12×3/16, HSS16×16×1/4, HSS18×18×1/4, HSS18×18×5/16, and HSS 20×20×5/16, which are noncompact composite for both axial compression and flexure.
| All current ASTM A500/A500M Grade C round HSS sections are compact composite according to the limits of Table I1.1a and Table I1.1b for both axial compression and flexure, with the exception of HSS6.625×0.125, | ||
|---|---|---|
| HSS7.000×0.125, | HSS9.625×0.188, | HSS10.000×0.188, |
| HSS10.75×0.188, | HSS12.750×0.188, | HSS12.750×0.250, |
| HSS13.375×0.188, | HSS13.375×0.250, | HSS14.000×0.188, |
| HSS14.000×0.250, | HSS16.000×0.250, | HSS16.000×0.312, |
| HSS18.000×0.250, | HSS18.000×0.313, | HSS20.000×0.250, |
| HSS20.000×0.313, | HSS20.000×0.375, | HSS22.000×0.313, |
| HSS22.000×0.375, | HSS24.000×0.313, | HSS24.000×0.375, |
| HSS26.000×0.375, HSS26.000×0.500, HSS28.000×0.375, and | ||
| HSS28.000×0.500, which are noncompact composite for flexure, and | ||
| HSS26.000×0.313, which is noncompact for compression and flexure. | ||