|FHWA > Infrastructure > Bridge > Steel > Heat Straightening|
FHWA Demonstration Project
Heat Straightening Repair for Damaged Steel Bridges*
*Including Ultrasound Impact Treatment Demonstration to Arrest Fatigue Cracks
and Improve Fatigue Life
Background | Speakers | Who Should Attend?
The use of heat straightening to repair damaged steel dates back to the 1930s. However, its use has tended to be more art than science, with techniques passed from one practitioner to the next. Over the past 15 years a significant effort has been devoted to providing an engineering basis for the application of heat straightening repair. The principles involved are also applicable to inducing curvature in new bridges.
Over the last few years, the Federal Highways Administration has sponsored a number of heat straightening workshops across the USA. These have been aimed at increasing awareness and expertise in the field of heat straightening repair of steel bridge girders that have been damaged by high load impacts. This same two day workshop will be held in Edmonton on April 7/8, 2003, and is an opportunity to increase local expertise in this subject
The purpose of the workshop is to provide the fundamental principles upon which heat straightening is based, and to show how these principles can be implemented in practice. The latest research findings will be presented to illustrate the basic principles. These include damage assessment, heating temperatures, the application of force during heat straightening, heating patterns and configurations, the effects of heat straightening on material properties and the classification of heating damage. With proper consideration of these parameters, a wide range of damage configurations can be repaired without significantly changing the steel properties.
The workshop will include both a presentation and a hands-on laboratory demonstration. Subjects covered will include:
- An overview of heat straightening and how to avoid potentially damaging mistakes.
- Determination as to what damage is heat straightenable.
- Heating patterns and how to use them to use them to repair different damage types.
- Heat straightening design.
- The behaviour of rolled and built-up shapes during and after heat straightening, including effects on material properties
- Estimation of the time required to straighten a bent piece of steel.
- Technical specifications, and inspection and supervision of repairs.
- Case studies, including a detailed repair using an interactive computer program.
In terms of practical applications, the presentation will focus on how to heat straighten the typical types of damage found in practice. Particular emphasis will be placed on:
- Flexural damage about both the major and minor axis.
- Localized bulges in plate elements.
- Twisting damage.
- Specialty items such as tubular members and connections.
Dr. Avent developed the training materials, much of which have not been previously published. The demonstration on the use of this material, particularly the interactive computer training, will be of interest to attendees. Each participant will receive a copy of the FHWA publication "Heat Straightening Repairs of Damaged Steel Bridges", a student's notebook and a set of two interactive CDs.
In addition to heat straightening, the workshop will include a demonstration and short introduction to fatigue strength enhancement through the application of ultrasonic impact treatment. This is a relatively new technique that was invented by Dr. Efim Statnikov in the Soviet Union, and has recently been the subject of further research at Lehigh University. This technique has implications for both new manufacture and for maintenance and repair procedures.
Dr. Richard Avent
Department of Civil and Environmental Engineering, Louisiana State University, Baton Rouge, Louisiana
Professor Avent holds the C.W.Armstrong distinguished professorship in the department of Civil and Environmental Engineering at LSU. He has over 30 years of teaching and research experience in structural engineering. He has focused his research efforts on structural repair and rehabilitation. He received the 1991 Wellington Prize from ASCE for his work on heat straightening, and the ASCE Innovation in Civil Engineering Award in 1995 for his work in developing epoxy repair methods for timber structures.
Krishna K. Verma
Federal Highway Administration, Washington, DC.
Mr. Verma is the Senior Welding Engineer in the Office of Bridge Technology, Federal Highway Administration Headquarters in Washington DC. He received a Master's Degree (Material Engineering) from Rensselaer Polytechnic Institute, a Master's Degree (Civil Engineering Structures) from the University of Calgary, and a BSCE Degree from Benaras Hindu University, India. He has coordinated FHWA's efforts to implement heat straightening for the repair of bridge structures.
Who Should Attend?
Owners, contractors, steel fabricators, bridge designers, inspectors, educators.
The workshop covers both the theory and the practical aspects of heat straightening, and so will be of value both to those involved in the design of repairs as well as those involved in the actual repair work on site.