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.

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