Heat Straightening of Impacted Steel Girders

OBJECTIVES: The objective ofthis study is to develop a guide to evaluate the types of damages resulting from oversize trucks impacting steel bridge girders and to identify the types of damages that are heat straightenable and the number of times that heat straightening may be considered. BACKGROUND: Recent studies in Maryland have shown that approximately one out of every five overpasses has been struck by an over-height vehicle. One-sixth of these bridges have received considerable damages, and required repair. Bridges that are hit are more likely to be located over interstate highways and are more likely to be hit more than once. The use of heatstraightening to repair damaged steel dates back to the 1930s, with low steel grades. Heatstraightening for steel bridge girders has tended to be more of an art than a science, with techniques passed ITom one practitioner to the next without proper technical documentations regarding: (1) how many times heat-straightening may be considered for different steel grades; (2) the behavior of built-up and rolled shapes during and after heat straightening; and (3) other technical issues including twisting damage of the web of the steel girders, crack migration after heat-straightening, flexural damage in both the major and minor axis, and localized bulges in the steel plates. FY 2007 PROPOSED WORK: It is anticipated that the evaluation of types of damages will be completed within the 2007 fiscal year. PROGRAMMED COST FY 2007: TOTAL ESTIMATED COST: $ 15,000 $125,000