|FHWA > Infrastructure > Bridge > HPS > Designers Guide|
|<< Previous||Contents||Next >>|
High Performance Steel Designers' Guide
Second Edition, April 2002
4.0 CONSTRUCTION SPECIFICATIONS
The provisions of the steel section of the State Standard Specifications for Roadway and Bridge Construction and the steel bridge Special Provisions are generally applicable to HPS, except for modifications as noted in the AASHTO HPS Guide and this HPS Designers' Guide, and supplemented with construction experience and research findings. A sample HPS construction specification is given in Appendix A - Sample HPS Special Provisions.
The AASHTO Guide Specifications for Highway Bridge Fabrication with HPS 70W Steel is now available exclusively through AASHTO, which can be ordered within the U.S. by calling the toll-free number (1-800-231-3475) or entering the bookstore online at www.transportation.org. The book code for the fabrication guide is HBF-1. Updates to this document will be initially available on the AISI website.
Fabricators of HPS have reported varied experiences with drilling HPS 70W Q&T steel. The experiences range from "no difference than Grade 50W steel" to "drills and reamers dull quickly". The HPS Steering Committee recommends that drilled or reamed holes be flooded with lubricant during drilling or reaming. Fabricators also note that mill scale removal by descaler or grinding is very difficult for the HPS Q&T steel, and mill scale removal by abrasive blasting requires about the same work effort as Grade 50W steel.
Fabricators report that there is no difference in flame cutting procedures when compared with Grades 36, 50 or 50W steels. Flame cut edges of HPS steels do not get excessively hardened (RC30 or higher) as in the case of flame cut edges of grade 50W steel. It is prudent to verify this in the first couple of HPS projects.
Predicting pre-cut camber gain or loss requires experimentation, especially with Q&T steels.
Welding of HPS 70W steel is currently restricted to the submerged arc and shielded metal arc welding processes for both Q&T and TMCP products. Other arc welding processes are being studied. It is expected that other welding processes commonly used in bridge fabrication will be approved in due course.
Previous | Contents | Next