Effect of Heat Straightening on Material Properties of Steel
Publication: Journal of Materials in Civil Engineering
Volume 12, Issue 3
Abstract
The use of heat straightening to repair damaged steel structures has gained popularity in recent years. However, applications have been limited due to concerns related to degradation of material properties after repair. Most research has been limited to small undamaged plate specimens where only one to three heats were applied. The purpose of this paper is to report on a study in which structural members were damaged and completely repaired by heat straightening, after which material properties were investigated. The research data indicate that heat straightening does affect mechanical properties of steel. Yield stress may increase by as much as 20%, especially in the vicinity of the apex of vee heats. Tensile strength also increases but at only half the rate of yield stress. The ductility as measured by percent elongation may decrease by one-third, and the modulus of elasticity may decrease by over 25% in some heated regions. A portion of this study included the evaluation of the effect of degree of damage on material properties after heat straightening. Damage with maximum strains up to 100 times the yield strain were repaired, and material properties were compared to members damaged with much smaller strains. The degree of damage had a minimal effect on the material properties of heat-straightened steel. Some members were damaged and completely heat straightened more than once to evaluate the effect of repetitive damage on the material properties of heat-straightened steel. Changes in material properties are small after two cycles of damage and repair. However, additional cycles produced a more brittle material and, in some cases, resulted in fracture of the material. In summary, heat straightening is a viable alternative for the repair of damaged structural steel. However, the user should be aware that some material properties will be changed during the process.
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References
1.
American Railway Engineering Association. ( 1946). “The shortening of eyebars to equalize the stress.” Bull. No. 460, Chicago.
2.
Avent, R. R. (1989). “Heat-straightening of steel: Fact and fable.”J. Struct. Engrg., ASCE, 115(11), 2773–2793.
3.
Avent, R. R., and Fadous, G. M. (1989). “Heat-straightening prototype damaged bridge girders.”J. Struct. Engrg., ASCE, 115(7), 1631–1649.
4.
Blodgett, O. W. (1972). “Distortion . . . How metal properties affect it.” Welding Engr., 57(2), 40–46.
5.
Ditman, O. ( 1961). “Determination of thermal shrinkage in structural steel.” MS thesis, University of Washington, Seattle.
6.
Harrison, H. L. (1952). “Straightening structural members in place.” Welding J., 31(5), 257s–262s.
7.
Hicks, C. R. (1982). Fundamental concepts in the design of experiments, 3rd Ed., Holt, Rinehart and Winston, New York.
8.
Horton, D. L. ( 1973). “Heat curved mild steel wide flange sections: An experimental and theoretical analysis. “MS thesis, University of Washington, Seattle.
9.
Moberg, K. L. ( 1979). “Damage assessment and contraction straightening of steel structures.” MS thesis, University of Washington, Seattle.
10.
Nicholls, J. I., and Weerth, D. E. (1972). “Investigation of triangular heats applied to mild steel plates.” Engrg. J., 9(3), 137–141.
11.
Pattee, H. E., Evans, R. M., and Monroe, R. E. (1969). “Flame straightening and its effect on base metal properties.” Summary Rep. to Ship Structure Committee Concerning First Phase of Project SR-185, Straightening Distorted Weldments, Battelle Memorial Institute, Columbus, Ohio.
12.
Pattee, H. E., Evans, R. M., and Monroe, R. E. (1970). “Effect of flame and mechanical straightening on material properties of weldments.” Summary Rep. on Ship Structure Committee on Project SR-185, Straightening Distorted Weldments, Battelle Memorial Inst., Columbus, Ohio.
13.
Putherickal, J. (1992). “Effects of heat straightening structural steel.” Final Rep. for MLR-91-3, Iowa Department of Transportation, Ames, Iowa.
14.
Roeder, C. W. (1985). “Use of thermal stress for seismic damage repair.” Final Rep. on NSF Grant CEE-82- 05260, University of Washington, Seattle.
15.
Rothman, R. L. (1973). “Flame straightened quenched and tempered steels in ship construction.” Rep. No. 247, Ship Struct. Com., U.S. Coast Guard, Washington, D.C.
16.
Rothman, R. L., and Monroe, R. E. (1973). “Effect of temperature and strain upon ship steels.” Rep. No. 235, Ship Struct. Com., U.S. Coast Guard, Washington, D.C.
17.
Shanafelt, G. O., and Horn, W. G. (1984). “Guidelines for evaluation and repair of damaged steel bridge members.” NCHRP Rep. No. 271, Transportation Research Board, National Research Council, Washington, D.C.
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Received: Apr 12, 1999
Published online: Aug 1, 2000
Published in print: Aug 2000
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