Fatigue Cracking—Problem for Welded Steel Bridges

Serial Information: Civil Engineering—ASCE, 1978, Vol. 48, Issue 4, Pg. 70-73

Document Type: Feature article

Errata: (See full record)


A recent problem with welded steel bridges is fatigue cracking at welded details. Fatigue cracks begin in small flaws or discontinuities at welded connections and grow to a critical size under the application of many load cycles. When a crack reaches a critical size, the fatigue strength of the member is exhausted and a fracture results. While research is showing how this problem can be avoided by careful design and quality control, repairs to existing structures are difficult. Repairs are hindered because the original design and materials must be used and because some types of repairs can actually aggravate the problem. To protect existing structures, bridges can be thoroughly inspected frequently so repairs can be made before the structure fails, or it can be assumed that a crack exists and repairs made to counteract the crack. The article is based on the contributions of four experts representing a university, FHWA, AISC and an investigative consultant.

Subject Headings: Steel bridges | Rehabilitation | Fatigue (material) | Cracking | Welding | Bridge design | Existing buildings | Discontinuities

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