An extensive experimental program was conducted to evaluate the performance of both black and galvanized high strength bolts for bridges. Seventy two a325 black bolts, 145 hot dip galvanized a325 bolts, 85 mechanically galvanized a325 bolts, and 83 black a490 bolts from several different suppliers, were tested under direct and torqued tension in order to evaluate the current installation practices and astm standard requirements for high strength bolts and to develop guidelines which will ensure proper installation and satisfactory performance of these bolts. An important parameter in the test program was the thread conditions of the bolts and nuts. Four thread conditions were examined: as received, cleaned, weathered and lubricated. Several types of lubricants were considered in the course of the experimental program. The results indicate that a great deal of the problems associated with the performance of high strength bolts lies in the vagueness of the current astm standards and the failure of the bolt suppliers to follow the requirements stated in these standards. A major recommendation in this study is to establish a unified standard which will cover the performance of fastener assemblages (bolt nut washer) under the responsibility of one committee. Guidelines for proper installation of high strength bolts are also given.
The current means and methods of verifying that high-strength bolts have been properly tightened are very laborious and timeconsuming. In some cases, ...
Links with this icon indicate that you are leaving a Bureau of Transportation
Statistics (BTS)/National Transportation Library (NTL)
Web-based service.
Thank you for visiting.
You are about to access a non-government link outside of
the U.S. Department of Transportation's National
Transportation Library.
Please note: While links to Web sites outside of DOT are
offered for your convenience, when you exit DOT Web sites,
Federal privacy policy and Section 508 of the Rehabilitation
Act (accessibility requirements) no longer apply. In
addition, DOT does not attest to the accuracy, relevance,
timeliness or completeness of information provided by linked
sites. Linking to a Web site does not constitute an
endorsement by DOT of the sponsors of the site or the
products presented on the site. For more information, please
view DOT's Web site linking policy.
To get back to the page you were previously viewing, click
your Cancel button.