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High Performance Steel
The Need
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High strength steels have been available for
years, but their use required more welding control and fabrication processes than
conventional strength steels. For this reason few bridge owners have been willing to risk
potential problems in fabrication, eventhough the design could be more efficient with
higher strength steel. |
The Technology
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A new grade of high performance steel,
HPS-485W or HPS-70W, developed by a cooperative program between the Federal Highway
Administration, the American Iron and Steel Institute, and the Department of the Navy in
August 1994; uses a new chemical composition that provides improved welding and toughness
properties. The increase in strength and performance will allow targeted use of HPS that
will extend the useful life of steel bridge structures; and even greater savings with the
reduction of the total steel weight.
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Although this new steel has the
same strength levels as the currently available AASHTO N270 Grade 70W steel, its unique
chemical and physical properties allow the use of more economical fabrication practices.
The main differences between M270 steel and HPS is: Carbon is almost half that of the
current steel, and sulfur is 1/10. Toughness value of over 200 Joules are commonly
obtained, as compared to values of 30 to 50 Joules for the current steel. |
The Benefits
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The benefits related to HPS include
enhancements in: weldability, toughness, corrosion resistance, ductility, fatigue and fire
resistance, formability, and strength. These factors combined lead to construction
elements of higher economic efficiency, ease of maintenance, and longer service life. Because of the low carbon levels, minimum or no preheat would be
required which allows increased productivity of fabrication and reduced cost.
HPS steel bridges can also be recycled at virtually 100%
which offers the greatest advantage when it comes to the environment. |
Status
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The technology won the 1997 CERF Pankow
Innovative Applications Award. According to the Civil Engineering Research Foundation
(CERF) report on the CONMAT program, there are several steel research projects planned
which focus on the production of new HPS, the development of new HPS structural systems,
and life-cycle cost analysis for HPS structures. There
are two states that are currently pioneering the use of HPS-70W for bridge structures.
Tennessee, with the construction of a bridge located on Route 53, Jackson County. In this
bridge the weight of steel was reduced almost 25% compared to the original bridge design
using the 50W grade steel. Nebraska, which is applying the HPS in a three phase project:
Phase I is a simply supported bridge, designed on 50W steel, but that will be constructed
on HPS-70W. This project will resolve questions related to constructability, familiarize
contractors with the new technology, and it will be used to update the AASHTO Bridge
Design Manual. Phase II will involve optimizing design and construction of a two span
continuous steel girder using HPS-70W. Phase III will include the construction of a steel
bridge using a new innovative design and HPS.
Twenty new bridges are being designed or fabricated in
several states, including Tennessee, Nebraska (2), Pennsylvania (2), North Carolina,
Virginia, New York (7), New Jersey, Massachusetts, Washington, West Virginia, Texas and
Florida.
The Building and Fire Research Laboratory, sponsored by the
National Institute of Standards and Technology, is currently developing design
methodologies and specifications for the design of HPS systems. |
Barriers
- High yield-to-tensile ratios (less ductile behavior such as
desirable in earthquakes).
- Cost premium for base material.
- Currently, the AASHTO Manual for Design of Steel Bridges
includes 50W limitations that prevent full utilization of the higher yield strength of HPS
(Jamshidi et al., 1997).
Points of Contact
- William Wright, Federal Highway Administration. Phone: (703)
285-2496
- Camille George Rubeiz, American Iron and Steel Institute.
1101 17th St., NW, Suite 1300 Washington, DC 20036, Phone: (202) 452-7118, Fax: (202)
463-6573
- William D. Michalerya, Manager of Industry Liaison &
Technology Transfer. ATLSS Center, 117 ATLSS Drive, Lehigh University Bethlehem, PA 18015
- John L. Gross, Structures Division, Building and Fire
Research Laboratory. Phone: (301) 975-6068
References
- "High Performance Steel Wins 1997 Pankow Innovative
Applications Award." Emerging Technology - Design and Construction Innovations
for Tomorrow. A publication of the Civil Engineering Research Foundation (CERF). Vol. 4,
No. 5, 1997.
- Wright, William. "High Performance Steel - Research
to Practice." Turner-Fairbank Highway Research Center, Public Roads Magazine
Online, Vol 60, No 4, Spring 1997.
- Gross, John L., "High-Performance
Steel." Building and Fire Research Laboratory Web page.
- Jamshidi, M., Fallaha, S., Azizinamini, A., Price, K., and
Cress, M. "Application of high performance steel in steel bridge
construction." Building to Last Structures Congress - Proceedings, Vol. 1, 1997,
ASCE, New York, NY.
- Sause, R. "Barriers to the use of High Performance
Steel in I-Girder Highway Bridges." Building and International Community of
Structural Engineers Structures Congress. Proceedings, Vol. 1, 1996, ASCE, New York, NY.
- Wassef, W.G., Kulicki, J.M, and Ritchie, P.A. "Bridges
of the 21st century with high performance steel." Building and International
Community of Structural Engineers Structures Congress. Proceedings, Vol. 1, 1996, ASCE,
New York, NY.
- “Materials for Tomorrow’s Infrastructure: A
Ten-Year Plan for Deploying High-Performance Construction Materials and Systems.”
Executive Report, Civil Engineering Research Foundation, 1994.
- Fisher, J.W., and Dexter, R.J. "High performance
steel bridges for the next century." International Symposium on Low-Carbon Steels
for the 90's. Proceedings. Minerals, Metals & Materials Society (TMS), 1993,
Warrendale, PA.
- 1999 Nova Award Nominations, The Nova Award,
Construction Innovation Forum, Inc., October 1998
Disclaimer Statement
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Neither the Construction
Industry Institute nor Purdue University in any way endorses this
technology or represents
that the information presented can be relied upon without further investigation. |
SSL04/LHM/MA
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