Identifier

etd-07062005-095648

Degree

Master of Science in Civil Engineering (MSCE)

Department

Civil and Environmental Engineering

Document Type

Thesis

Abstract

The heat straightening method of repair for damaged steel structures has been employed for many years. The method was based on the experience of practitioners. Recent research has given an engineering background for the technique and established certain procedures and guidelines to be followed while using heat straightening. Although a scientific basis has now been established, there still exist some major gaps in the data. Misuse of the heat straightening technique has produced fractures in the steel during repair.There are two parameters that may be keys to limiting fracture sensitivity: degree of damage and application of jacking force stress during the repair of the damaged steel. Currently, research data supports repairing damaged steel strained to 100 times yield strain if jacking forces used in repair are limited. No data exist for more severe damage such as caused by high impact. The formation of a link between degree of damage and jacking ratio may lead to a performance-based design. The purpose of this research is to investigate behavior of plate elements bent about their weak (minor) axes and then heat straightened. Specifically relationships between material properties, jacking force, degree of damage and amount of movement during straightening will be investigated. The results will be used to develop recommended heating and jacking patterns for repair of localized damage. This research will provide a method of repair for fracture critical situations such as damaged rigid beam-to-column connections and damaged steel subjected to dynamic behavior for machinery and fire damaged structures. The damaged plates were repaired using heat straightening technique. The movement of plates was compared to strain ratio and jacking ratio. Movement was found to be directly proportional to jacking ratio and inversely proportional to the strain ratio. Degree of damage did affect material properties of repaired plates. A locally damaged flange was repaired using new heating pattern developed by finite element modeling. More widespread use of the heat straightening technique would lead to both efficient and economical repair of damaged steel structures since the process is fast and minimizes disruptions related to use of the structure.

Date

2005

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Richard R. Avent

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