ASTM A1085/A1085M, Standard Specification for Cold-Formed Welded Carbon Steel Hollow Structural Sections (HSS), was introduced in 2013 and was listed in CSA S16 Clause 5.1.3 for the first time in the 2014 edition.


Figure 1

Hollow Structural Sections

Wall thickness and mass tolerances for A1085 products are essentially the same as those specified for HSS in CSA G40.20-13. Therefore, section properties provided for CSA G40.20 HSS in the Handbook of Steel Construction, which are based on the nominal wall thickness, depth, width or diameter, may be used for design.

The factored axial compressive resistance of an A1085 HSS column may be determined in accordance with S16-14 Clause 13.3.1 with the value of “n” taken as 1.34. The factored axial compressive resistance tables for Class C G40.20 HSS Columns in the Handbook may be used, provided an adjustment for the small difference in Fy values (345 MPa vs. 350 MPa) is taken into account.

Purchasers of A1085 HSS may specify heat treatment, as a Supplemental Requirement S1, which also conforms to the stress-relieved requirement for Class H G40.20 HSS. A value of n = 2.24 may therefore be used for A1085 HSS supplied with Supplemental Requirement S1.

With respect to notch toughness, ASTM A1085 HSS are produced to meet requirements comparable to those of CSA G40.20/21 350WT Category 1. The material is required to conform to a minimum average Charpy V-notch impact value of 34 J at 4°C, as represented by the test specimen. It is noted, however, that the use of notch-tough steel for gravity columns is exceptional.

In addition, a maximum yield stress at 485 MPa as well as a minimum yield stress at 345 MPa apply. Minimum corner radius control is another measure unique to A1085 square and rectangular HSS. All in all, A1085 HSS are superior to A500 products in various aspects.

Information on the availability of HSS produced to ASTM A1085 may be found at this link: