High Performance Steel Designers' Guide
In 1994, a cooperative research program between the Federal Highway Administration (FHWA), the U.S. Navy and the American Iron and Steel Institute (AISI) was launched to develop high performance steels for bridges. A Steering Committee of experts from FHWA, Navy, AISI, and plate producing member companies, steel fabricators and American Welding Society (AWS) was formed to oversee and guide the research.
The initial research program was to develop HPS 70W and HPS 100W, weathering steel grades, with toughness Zone 3 requirements, and with significant improvement in weldability . With the successful use of HPS 70W, bridge engineers are requesting an HPS version of 50W grade steel. They are interested in the higher toughness and improved weldability. HPS 50W and HPS 70W grades are now commercially available and the HPS 100W is in development. This HPS Designers' Guide only covers HPS 50W and HPS 70W.
HPS 70W has been most extensively researched, tested and used to date. As of this writing, a total of about 21 HPS 70W steel bridges are in service and 13 more bridges are in various stages of construction nationally. Many are ready for construction, being designed and in the planning stage. HPS 50W is only available and used recently.
The following four documents cover the design, fabrication and construction of steel bridges using high performance steels:
- AASHTO LRFD Bridge Design Specifications with Interims (AASHTO LRFD)
- AASHTO Standard Specifications for Highway Bridges, 16th. Edition, 1996, 2000 Interim (AASHTO LFD)
- AASHTO Guide Specifications for Highway Bridge Fabrication with HPS 70W Steel (AASHTO HPS Guide)
- ANSI/AASHTO/AWS D1.5-95 Bridge Welding Code with Addendums (AWS Code)
These documents reflect the findings and experiences on the applications of HPS by researchers, fabricators, manufacturers, owners and engineers working with high performance steels, and are the best references, as they are modified over time. The designers must make sure that all or parts of these documents are made a part of the contract document and add any supplemental requirements in the project special provisions.
This HPS Designers' Guide discusses the key elements of the above four documents as applied to high performance steels, identifies factors that should be considered, and provides sources and references where designers can obtain additional information to assure successful use of HPS in highway bridge construction. This Guide will be updated periodically to keep pace with the latest developments in HPS, and as AASHTO and AWS modify their codes to reflect new research findings and construction experiences.