A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Understanding distortion induced fatigue
Prior to the mid 1980’s, the vertical stiffener, used to connect the cross-bracing system to the main girders in composite bridges of steel and concrete, was often cut short away from the flange in tension. This practice was stopped due to early fatigue cracks being developed in the region where the vertical stiffener was terminated. The early damage was due to distortion of the web-gap, and this type of damage is referred to as distortion induced fatigue damage. Internationally, several hundreds of bridges have experienced distortion induced fatigue damage, and there are still hundreds of bridges in service which are prone to this type of damage. This report covers two case studies that are chosen to be representative of the Swedish bridge stock for bridges built prior to mid 1980’s. Furthermore, a parametric study, covering a few influencing factors is conducted. Most of the presented data in this report are produced through numerical models. However, for one of the case study bridges a field measurement was undertaken, for which several strain gauges were attached to critical areas of the bridge and a vehicle of known axle distance and weight made several passages over the bridge. This report aims at improving the understanding of distortion induced fatigue and to help identify bridges that are susceptible to this type of damage. The results from the study indicates that not all bridges that have a stiffener that is cut short from the flanges are in need of retrofitting procedures. Furthermore, the factors that sets the different bridges apart and that are the most influential for distortion induced fatigue, are the rotation of the cross-section, the deformation of the deck plate, the uneven deflection and the distance between the cross-bracings and the supports. ; QC 20210222
Understanding distortion induced fatigue
Prior to the mid 1980’s, the vertical stiffener, used to connect the cross-bracing system to the main girders in composite bridges of steel and concrete, was often cut short away from the flange in tension. This practice was stopped due to early fatigue cracks being developed in the region where the vertical stiffener was terminated. The early damage was due to distortion of the web-gap, and this type of damage is referred to as distortion induced fatigue damage. Internationally, several hundreds of bridges have experienced distortion induced fatigue damage, and there are still hundreds of bridges in service which are prone to this type of damage. This report covers two case studies that are chosen to be representative of the Swedish bridge stock for bridges built prior to mid 1980’s. Furthermore, a parametric study, covering a few influencing factors is conducted. Most of the presented data in this report are produced through numerical models. However, for one of the case study bridges a field measurement was undertaken, for which several strain gauges were attached to critical areas of the bridge and a vehicle of known axle distance and weight made several passages over the bridge. This report aims at improving the understanding of distortion induced fatigue and to help identify bridges that are susceptible to this type of damage. The results from the study indicates that not all bridges that have a stiffener that is cut short from the flanges are in need of retrofitting procedures. Furthermore, the factors that sets the different bridges apart and that are the most influential for distortion induced fatigue, are the rotation of the cross-section, the deformation of the deck plate, the uneven deflection and the distance between the cross-bracings and the supports. ; QC 20210222
Understanding distortion induced fatigue
Skoglund, Oskar (author)
2021-01-01
Paper
Electronic Resource
English
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