Effects of Multiple Damage-Heat Straightening Repairs on Steel Beams

Kowalkowski, Keith J; Varma, Amit H.

doi:10.3141/2028-08

Cited by 5 publications

(3 citation statements)

References 8 publications

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“…The heating temperatures were between 1,100°F and 1,200°F as required, and the restraining force was maintained during heating and slowly reduced during cooling as recommended by FHWA guidelines (4). The behavior was similar to that shown by Kowalkowski and Varma (7).…”

Section: Experimental Behavior Damage and Repairsupporting

confidence: 88%

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Effects of Realistic Heat-Straightening Repair on Damaged Steel Beams

Sohn

Varma

Cha

2014

Transportation Research Record

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Realistic implementation of heat straightening in the field can include imperfections such as temperatures much higher or lower than recommended values, overstraining, mechanical hot bending, and multiple heat straightening. Experimental investigations were performed to evaluate the effects of realistic heat straightening with imperfections on damaged steel beams. Six steel beam specimens were fabricated from A36 steel plates and tested to evaluate the effects of various damage and repair parameters on realistic heat-straightening repair. Test specimens were statically damaged by using a hydraulic actuator, and heat-straightening repaired by applying Vee heats and restraining forces in the plastically deformed region. The damage and repair parameters considered in the test were damage magnitude, restraining force, maximum heating temperature, and number of multiple damage–repair cycles. The material properties, including the structural properties, and the fracture toughness of the damaged–repaired beam specimens were determined and evaluated. Specimens subjected to overheating (up to 1,400°F) during repair and those subjected to heating up to 1,200°F had similar structural properties and fracture toughness values after repair. Specimens subjected to one or three damage–repair cycles had similar structural properties and fracture toughness. However, specimens subjected to mechanical hot bending [i.e., heat-straightening repair with underheating (temperature less than 1,000°F and excessive restraining force over 50% of the plastic moment capacity of the section)] had poor fracture toughness values.

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Section: Experimental Behavior Damage and Repairsupporting

confidence: 88%

“…The test setup was originally designed to damage and repair W24 × 76 steel beams (7). Therefore, the dimensions of the test A36 steel sections needed to be equivalent to the W24 × 76 section.…”

Section: Test Specimensmentioning

confidence: 99%

Effects of Realistic Heat-Straightening Repair on Damaged Steel Beams

Sohn

Varma

Cha

2014

Transportation Research Record

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“…Kowalkowski and Varma ( 6 – 8 ) have conducted detailed experimental investigations to evaluate the effects of multiple damage–heat straightening repair cycles on the structural properties, fracture toughness, and microstructure of A36, A588, and A7 bridge steels.…”

Section: Introductionmentioning

confidence: 99%

Effects of Imperfections in Heat Straightening Repair of Steel Beam Bridges

Sohn

Varma

Connor

2018

Transportation Research Record

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A 40 ft. long two-span continuous steel bridge with two composite beams was constructed in the laboratory and subjected to damage followed by heat straightening repair. A36 steel section (W30 × 90) was used for the main girders (beams). Four spans (specimens) of the test bridge were statically damaged at each midspan using a hydraulic actuator, and subsequently repaired by applying Vee heats and restraining forces in the damaged region. Restraining force magnitude (corresponding to 0.4 Mp: 6.2 kips and 0.6 Mp: 9.5 kips), maximum heating temperature (800°F, 1200°F, and 1400°F), and the number of multiple damage-repair cycles (one and three cycles) were considered as the test parameters. The steel material properties were measured by taking samples from the repaired areas, and compared with undamaged steel material properties. Samples taken from specimens subjected to overheating (up to 1400°F) had similar structural properties and fracture toughness values as those taken from specimens subjected to normal heating (up to 1200°F). Specimens repaired with overstraining (0.6 Mp) combined with underheating (up to 800°F) required the largest number of heating cycles to fully repair the same damage. The fracture toughness of samples taken from specimens subjected to multiple (three times) damage-repair cycles was lower (decreased to about 84%) than the fracture toughness of samples taken from specimens subjected to only one damage-repair cycle. Therefore, multiple heat straightening repairs of a damaged beam should be performed with caution. With reference to serviceability performance for AASHTO HL-93 live load, the midspan deflections of beam specimens subjected to damage and heat straightening repair were comparable to those of undamaged beam specimens.

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