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FHWA Demonstration Project
Heat Straightening Repair for Damaged Steel Bridges
San Antonio, Texas
January 31, 2005 (Monday) to February 1, 2005 (Tuesday)
Heat straightening is a repair process in which limited heat is applied in specific patterns to plastically deformed regions of damaged steel in repetitive heating and cooling cycles to produce a gradual straightening of the material. The process relies on internal and external restraints to produce "thickening" or "upsetting" during the heating phase and "in-plane contractions" during the cooling phase. This technique is an effective and economical repair method for many damaged steel bridges.
The use of heat straightening to repair damaged steel dates back to the early days of welding, when steel fabricators observed how the heat from welding caused distortion and they began experimenting with ways to correct the distortion by heating the steel in specific patterns. For half a century, heat straightening techniques have been applied to bends and distortions in steel members in order to restore the original shape. However, for many years this method has been more of an art than a science, depending on a few skillful practitioners. Over the past 15 years, technicians, engineers, and researchers have made significant efforts to quantify heat straightening in engineering terms, leading to the development of appropriate techniques and methods.
To facilitate the proper use of this technique in the repair of steel bridges, the FHWA has sponsored a project called "Demonstration Project on Heat-Straightening Repair of Damaged Steel Bridge Members" to develop a set of comprehensive training materials on heat straightening and to train technicians and engineers nationwide. The workshop is based on the research of Dr. Richard Avent, author of publication FHWA-IF-99-004, "Heat-Straightening Repairs of Damaged Steel Bridges - A Technical Guide and Manual of Practice."
The workshop will be conducted on two full days on January 31, 2005, (Monday) and February 1, 2005, (Tuesday) at the TxDOT Bexar Metro Area Office (9320 SE Loop 410, in San Antonio, TX 78223). It will start at 8:30 AM on January 31st and will include a presentation and a hands-on laboratory demonstration. A tentative agenda is attached.
Heat Straightening Demonstration - The demonstration will address fundamental principles upon which heat straightening is based and show how these principles can be implemented. These principles include damage assessment, heating temperatures, application of external restraining forces, heating patterns, effects of heat straightening on material properties, and the classification of heating damage. Subjects will include:
Overview of heat straightening and how to avoid potentially damaging mistakes
Determination of the type of damage for which heat straightening is suitable
Heating patterns and how they are used to repair different types of damage
Design of heat straightening procedure
Behaviors 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, inspection, and supervision of repairs
Case studies, including a detailed repair using an interactive computer program
For practical applications, the presentation will focus on how to heat straighten the typical types of damage to steel, particularly on:
Flexural damage about both the major and minor axis
Localized bulges in plate elements
Damage to special components such as tubular members and connections
Each participant will receive a copy of the FHWA publication FHWA-IF-99-004, "Heat-Straightening Repairs of Damaged Steel Bridges - A Technical Guide and Manual of Practice," a student's notebook, and a set of two interactive CDs. At the completion of the course, a training certificate signed by Dr. Avent will be issued to each student attending the two-day class.
Ultrasonic Impact Treatment (UIT) Demo - In addition to the heat straightening demonstration, the workshop will include a demonstration and introduction of UIT, which can be used to improve fatigue performance of welded details and repairs in steel members. The UIT demonstration will be conducted by the representatives of Applied Ultrasonics.
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 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.
Mr. Krishna K. Verma, Federal Highway Administration, Washington, DC.
Mr. Verma is the Principal Bridge Engineer - Structural Fabrication in the Office of Bridge Technology, Federal Highway Administration Headquarters in Washington, DC. Mr. Verma 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.
Training Facilities and accommodations
This workshop will be held in a conference room and a nearby shop in the facility of the TxDOT Bexar Metro Area Office. There is no charge for the workshop; however, attendees will be responsible for all other expenses including travel and hotel accommodations. Attendees should bring dark sunglasses to the laboratory session. Space for attendees is limited, so register early.
The availability of hotel rooms in San Antonio is often limited, so you are encouraged to make hotel reservations as early as possible.
For the convenience of participants, a barbeque lunch will be offered at a cost of approximately $5 each day. At the beginning of the workshop a collection will be taken so that an adequate number of meals are provided.
For attendees from TxDOT, a training code has been established for the subject course. The training code is 15MNT3.
Contacts and Coordinators
FHWA:Peter Chang, P.E.
Title: Bridge Engineer
Address: 300 E. 8th Street, Room 826, Austin, TX 78701
Jon Kilgore, P.E.
District Bridge Engineer, TxDOT San Antonio District, San Antonio
Address: 4615 NW Loop 410, Building 4, San Antonio, TX 78229-0928
Dingyi Yang, P.E.
Bridge Field Engineer, TxDOT Bridge Division, Austin
Address: 118 E. Riverside Dr. Austin, TX 78702