ASTM has released a new HSS standard, A1085 - 13 Standard Specification for Cold-Formed Welded Carbon Steel Hollow Structural Sections (HSS), which will result in the production of improved hollow structural sections (HSS). This specification is a big step forward in simplifying HSS design and usage, thereby making it a more desirable option for HSS.
"We were committed to the development of the new ASTM A1085 specification as it was needed to improve the performance of HSS used in structural applications such as seismic load resisting systems, bridge structures and other dynamically loaded structures," said Brad Fletcher, senior sales engineer with AISC-member Atlas Tube. According to Fletcher, round and square members from 6 in. and up will likely be the main shapes Atlas initially produce under the new specification.
Benefits include:
- Tighter material tolerances and a single minimum yield stress of 50 ksi. Because of the more stringent wall tolerances and the addition of a mass tolerance, it's anticipated that AISC's Committee on Specifications will shortly issue guidelines allowing 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. And more area available for design and a higher minimum yield mean that HSS will become a more economical and efficient design option.
- Maximum specified yield stress of 70 ksi. This will result in a lower expected yield strength for seismic design, and thereby reduce capacity design requirements when HSS are the yielding element. For example, with ASTM A1085 HSS braces in a braced frame, the beams and columns will have lower required strengths. ASTM A1085 is the only HSS specification used in North America or Europe that limits the maximum yield stress.
- Standard requirement for notch toughness. The specification will require all HSS to meet a minimum Charpy V-notch (CVN) value of 25 ft-lb at 40°F, which corresponds to AASHTO Zone 2 requirements. Having the minimum CVN required makes HSS more suitable for use in dynamically loaded structures.
"A1085 makes designing with HSS easier and more efficient for both building and bridge construction," said John Simon, vice president of sales with AISC-member EXLTUBE. "We are hearing a great response from structural engineers who have begun to learn about this new spec through efforts at NASCC: The Steel Conference and other communications, and we're working closely with AISC and the Steel Tube Institute to begin promoting A1085 to our customers. EXLTUBE will be supporting these efforts with inventory as soon as we've determined the sizes the market will require from us."
John Tassone, marketing manager for AISC-member Independence Tube, also commented: "We will be manufacturing and inventorying the product as the need arises," adding that the company will likely concentrate on squares and rounds 4 in. and above to start.
For specific price and availability information, please contact HSS producers and service centers. Contact information is available at www.aisc.org/hss.
About the American Institute of Steel Construction
The American Institute of Steel Construction, headquartered in Chicago, is a not-for-profit technical institute and trade association established in 1921 to serve the structural steel design community and construction industry. AISC's mission is to make structural steel the material of choice by being the leader in structural steel-related technical and market-building activities, including: specification and code development, research, education, technical assistance, quality certification, standardization, and market development. AISC has a long tradition of service to the steel construction industry of providing timely and reliable information.
Related Stories
| Feb 15, 2011
Iconic TWA terminal may reopen as a boutique hotel
The Port Authority of New York and New Jersey hopes to squeeze a hotel with about 150 rooms in the space between the old TWA terminal and the new JetBlue building. The old TWA terminal would serve as an entry to the hotel and hotel lobby, which would also contain restaurants and shops.
| Feb 15, 2011
New Orleans' rebuilt public housing architecture gets mixed reviews
The architecture of New Orleans’ new public housing is awash with optimism about how urban-design will improve residents' lives—but the changes are based on the idealism of an earlier era that’s being erased and revised.
| Feb 15, 2011
LAUSD commissions innovative prefab prototypes for future building
The LA Unified School District, under the leadership of a new facilities director, reversed course regarding prototypes for its new schools and engaged architects to create compelling kit-of-parts schemes that are largely prefabricated.
| Feb 15, 2011
New 2030 Challenge to include carbon footprint of building materials and products
Architecture 2030 has just broadened the scope of its 2030 Challenge, issuing an additional challenge regarding the climate impact of building products. The 2030 Challenge for Products aims to reduce the embodied carbon (meaning the carbon emissions equivalent) of building products 50% by 2030.
| Feb 15, 2011
New Urbanist Andrés Duany: We need a LEED Brown rating
Andrés Duany advocates a "LEED Brown" rating that would give contractors credit for using traditional but low cost measures that are not easy to quantify or certify. He described these steps as "the original green," and "what we did when we didn't have money." Ostensibly, LEED Brown would be in addition to the current Silver, Gold and Platinum ratings.
| Feb 15, 2011
AIA on President Obama's proposed $1 billion investment in energy conservation
The President’s budget increases the value of investment in energy conservation in commercial buildings by roughly $1 billion, reports AIA 2011 President Clark Manus, FAIA. The significant increase from the current tax deduction of $1.80 per sq. ft. now on the books is an increase for which the AIA has been advocating in order to encourage energy conservation.
| Feb 14, 2011
Sustainable Roofing: A Whole-Building Approach
According to sustainability experts, the first step toward designing an energy-efficient roofing system is to see roof materials and systems as an integral component of the enclosure and the building as a whole. Earn 1.0 AIA/CES learning units by studying this article and successfully completing the online exam.