|Project Name:||Fracture Resistance of Cold Bent Steel|
Office of Infrastructure Research and Development |
|Team:||Bridge and Foundation Engineering Team|
Infrastructure Research and Technology Strategic Plan and Roadmap|
|Project Description:||Bending steel cold reduces its ductility and also its toughness. There is a concern that cold bent steel may be susceptible to fracture because the toughness is reduced from that of the parent material. This project is trying to explore if this is a concern, and explore means of mitigating it.|
|Start Date:||March 1, 2013|
|End Date:||August 30, 2015|
|Goals:||To determine allowable bending radii of steel plates such that fracture is not a concern. This may include enhanced material specifications.|
|Background Information:||Federal Highway Administration (FHWA) has been pushing accelerated bridge construction (ABC) techniques though the Every Day Counts (EDC) initiative. Prior to EDC, the second Strategic Highway Research Program (SHRP2) had a project to identify rapid bridge construction techniques. The SHRP2 R04 report highlighted 11 ABC concepts ready for implementation, one of these was entitled "Pre-topped cold-bent trapezoidal box-girder modules for simple spans up to 100 feet". The report further acknowledged that the American Association of State Highway and Transportation Officials (AASHTO) Construction Specifications, at the time, were silent on the use of cold bending, in particular the concern of fracture susceptibility. The 2010 3rd Edition of the AASHTO Construction Specification outlined that cold bending could be used if approved, and listed recommended minimum bend radii; however, the strains in the material at these radii were on the order of 30%, almost bringing the material to the fracture point. In the 2012 Interims of the Construction Specifications, the table of minimum bending radii were changed universally to five times the plate thickness requirement. However, the reference this change was based on was not a comprehensive study and this project intents to look into the problem deeper.|
|Test Methodology:||small and full-scale testing|
|Expected Benefits:||Open doors to more fabrication methods for steel bridges beyond bolting and welding.|
|Deliverables:||1. Name: Final Report|
Product Type(s): Research report
Description: The project will generate a final report so others will be able to understand the nature of the work, results attained, and conclusions from it.
2. Name: Recommended changes to American Association of State Highway and Transportation Officials (AASHTO) Bridge Design Specifications and/or AASHTO Construction Specifications.
Product Type(s): Research report, Draft standard, specifications, or guidelines
Description: The results of the project will likely determine needs changes to some AASHTO specifications. This product will be draft ballot items that AASHTO could vote on.
Bridges and other structures|