Effects of multiple damage-heat straightening repair cycles on the structural properties and serviceability of steel beam bridges
Abstract
Steel members of bridges and buildings are often subjected to damage (plastic deformations) due to large and sudden impacts. Heat straightening is a cost-effective and efficient technique for repairing the damage. There is a lack of knowledge regarding the effects of multiple damage-heat straightening repair cycles on the structural properties, toughness, and microstructure of steels. Objectives of this research are: (a) review the current state-of-knowledge of heat straightening repair of damaged steel bridges, (b) experimentally investigate the effects of single and multiple cycles of damage followed by heat straightening repair on the structural properties of typical bridge steels with laboratory-scale and large-scale specimens, (c) analytically investigate the effects of damage and heat straightening repair on the serviceability performance and load capacity of composite steel bridges, (d) develop recommendations and guidelines for evaluating and replacing (if necessary) steel beams subjected to damage-repair cycles. The review indicates that there is a significant lack of knowledge and guidelines for evaluating the effects of multiple damage-heat straightening repair cycles on steel structural properties. The most frequently damaged-repaired steel types in Michigan are A7, A373, A588, A36, and A572 Gr.-50 in descending order. The experimental results indicate that A36 and A7 steel beams should be replaced after three damage-repair cycles and A588 steel beams can be subjected to five damage-repair cycles. Overheating the A36 steel to temperatures > 1200°F has improves the fracture toughness of the damage-repaired steel significantly. The analytical results indicate that damaged and damaged-repaired bridge beams are still capable of handling heavy traffic loads. The welded connection between web stiffeners and top flange of plate girder bridges are critical after damage and repair. Concrete cracking or fracture may occur.
Degree
Ph.D.
Advisors
Varma, Purdue University.
Subject Area
Civil engineering
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