Benefit
Tighter material tolerances and a single minimum yield stress of 50 ksi.
- More stringent wall tolerances and the addition of a mass tolerance mean the full nominal wall thickness can be used for design of HSS. This means no longer needing to reduce the nominal wall thickness by 0.93 as prescribed in the AISC Steel Construction Manual for both member selection and connection design.
- More area available for design and a higher min yield means that HSS are more economical and more efficient.
Maximum specified yield stress of 70 ksi.
- The maximum yield will result in a lower expected yield strength and reduce capacity design requirements and column required strengths in seismic designs.
- This is the only specification used in North America or Europe that limits the maximum yield stress in HSS.
Standard requirement for Charpy notch toughness.
- New specification will require all HSS to meet a minimum CVN value of 25 ft-lb @ 40° F, which corresponds to AASHTO Zone 2.
- Having the minimum CVN required makes HSS more suitable for use in dynamically loaded structures.
Cost Savings
Specifying ASTM A1085 HSS results in enhanced performance and substantial cost saving. Here’s how:
HSS produced to ASTM A1085 is a premium product that has a higher level of performance than A500. Because of the tighter material tolerances, there is more steel required to produce the product compared to HSS produced to ASTM A500. Additional regular testing is also required to satisfy the CVN requirements. These additional features lead to a price extra of $3/CWT, or $60/ton for HSS produced to ASTM A1085. This is about a 6-7% increase over current pricing of HSS produced to A500. However, designing with HSS A1085 often leads to improved utilization of material, which increases the potential of cost savings.
Cost Savings
Let's say you had an axial column load demand of 380 kips, an unbraced length of 15 ft. and you are constrained to using an 8" square column. An HSS 8 x 8 x ½, A500, Grade B, KL = 15 ft. has an axial capacity of 441 kips and an HSS 8 x 8 x 3/8, A500, Grade B, KL = 15 ft. has an axial capacity of 343 kips. You would select the HSS 8 x 8 x ½ with a nominal weight of 48.85 plf. An HSS 8 x 8 x 3/8, A1085, KL = 15 ft. has an axial capacity of 390 kips which would satisfy the load demand and have a lower nominal weight of 37.69 plf. This is a weight savings of approximately 23%.
Enhanced Performance
For example, an HSS 8 x 8 x ½, A500, Grade B with an unbraced length of 15 ft. has an axial capacity of 441 kips. An HSS 8 x 8 x ½, A1085 with an unbraced length of 15 ft. has an axial capacity of 500 kips. This results in more than a 13% increase in capacity, with no increase in nominal weight.
ASTM A1085 Flyer 
