PROBABILITY THEORY FOR HIGHWAY BRIDGE FATIGUE STRESSES PHASE II
Recent years have seen an increased presence of factors which relate to the occurrence of fatigue cracks on steel highway bridge girders. The 1963 modifications in AASHTO fatigue specifications often caused fatique limits to govern section sizes and in some cases causing changes in design usage of high strength steel and certain weld attachments. This study combined statistical data on truck loads, bridge behavior and measurements and laboratory tests of steel attachments to develop a model of fatigue life prediction. A fatigue design specification was derived from the study which permits truck volume and loadometer survey data to be considered in calculating the allowable design stresses. This can lead to more economic girder sections. To illustrate the proposed design procedure several single and multi-span bridges are analyzed and compared in detail using the proposed method and current AASHTO fatigue specifications including modification of the distribution factor. The fatigue design loading proposed herein represents the actual behavior conditions with respect to truck dimensions and weights, girder distribution factors, headway spacing between trucks and dynamic impact. This work resulted from examination of the Ohio bridge measurement project which recorded over 20,000 truck passages on 10 bridges. The data is described in the current report. Based on this study it is possible to specify a load and design technique so that fatigue damage has a small chance of occurrence under proper detailing and inspection procedures. Economic optimization methods based on a risk model including damage consequences are also discussed and may be used for rating and evaluation of possible increased truck load limits.
- Study conducted in cooperation with U.S. Department of Transportation, Federal Highway Administration. Sponsored by Ohio Department of Transportation.
Case Western Reserve UniversityDepartment of Civil Engineering, 10900 Euclid Avenue
Cleveland, OH United States 44106-7201
- Moses, F
- Pavia, A P
- Publication Date: 1976-8
- Pagination: 183 p.
- TRT Terms: Design standards; Fatigue (Mechanics); Girder bridges; Highway bridges; Load limits; Mathematical models; Probability theory; Trucks
- Uncontrolled Terms: Fatigue life; Models
- Subject Areas: Bridges and other structures; Data and Information Technology; Highways; Motor Carriers;
- Accession Number: 00142559
- Record Type: Publication
- Source Agency: National Technical Information Service
- Report/Paper Numbers: OHIO-DOT-02-76 Final Rpt.
- Files: TRIS
- Created Date: Dec 15 1976 12:00AM