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Description / Abstract:
INTRODUCTION
The intent of this Guide Specification for Highway Bridge
Fabrication With HPS 70W Steel, 2nd Edition, hereafter
referred to as the HPS Fab Guide is to provide owners, designers
and fabricators with the latest recommended methodology to
fabricate and weld structures using ASTM A709 or AASHTO M270, Grade
HPS 70W (HPS 485W) steel, referred to hereinafter as HPS 70W. The
HPS Fab Guide is recommended for use until such time that
other industry codes and specifications have included this product
and have provided the necessary regulatory provisions to
successfully fabricate bridges. The 2nd Edition is based on
continued research and experience with fabrication and welding, and
will be updated as additional research is conducted and additional
experience is gained. The latest in research and experience with
HPS 70W steel may be obtained by contacting the American Iron and
Steel Institute (AISI) website at www.steel.org.
HPS 70W is now furnished in as-rolled or control-rolled
condition, thermo-mechanical control processed (TMCP) or quenched
and tempered (QT) steel plates. Research continues to be
conducted under a cooperative agreement sponsored by the Federal
Highway Administration (FHWA), the U.S. Navy, and the American Iron
and Steel Institute (AISI). A High Performance Steel Steering
Committee and a Welding Advisory Group, including representatives
of steel plate manufacturers, welding consumable manufacturers,
steel bridge fabricators, bridge owners, industry, academia and
other experts oversees research and development of High Performance
Steel, and monitors its use. Appendix B1 contains a
partial list of reports supporting research findings.
High Performance Steel has made a very rapid entry into the
bridge industry. The first HPS 70W bridge was placed in service in
December 1997, only three years after the onset of the cooperative
research effort. Within the next four years, over 45 bridges were
placed in service that have incorporated HPS 70W exclusively in
steel plate girders, as part of homogeneous, mixed or hybrid plate
girders, or in floor systems, deck trusses, and suspension bridges
totaling nearly 4½ million square feet of deck area. Thirty-six
owners, including states, authorities and other agencies, chose to
take advantage of HPS 70W in nearly 180 steel bridges during this
period.
There may be length, width or thickness limitations when using
these alternately produced products, based on manufacturer specific
capabilities. In addition, some of the required mechanical
properties of HPS 70W may not be achieved in the non-quenched and
tempered plates above some given thickness, depending on mill
capability.
Initially, submerged arc welding (SAW) and shielded metal arc
welding (SMAW) were the only processes recommended for welding high
performance steel. Based on research, certain consumables for the
flux cored arc welding (FCAW) and gas metal arc welding (GMAW)
processes are now included. In addition, the HPS Fab Guide
recommends specific consumables that have demonstrated that they
are capable of successfully producing acceptable quality welds. In
general, research and experience have shown that the potential for
hydrogen induced cracking is minimized when diffusible hydrogen is
controlled to a maximum of H8.
As additional welding processes and consumables are evaluated,
the HPS Fab Guide will be updated to include those
recommended for welding HPS 70W steel.
All references made hereafter to AWS D1.5 shall mean the
AASHTO/AWS D1.5M/D1.5:2002 Bridge Welding Code.
1 Copies of these and other applicable reports are
available by contacting the American Iron and Steel Institute
(AISI) at www.steel.org, or phoning 202-452-7100.