Service life static fatigue

In addition to the rehabilitation techniques produced in Step 9 for the fatigue-life extension of critical bridge members and their connections, a set of alternative rehabilitation scheme will be produced which can be used efficiently and economically to improve overall static and dynamic service-load capacity of each characteristic group of the railroad bridge structural systems. For this purpose various repairing and strengthening schemes will be analysed from the engineering point of view. 

This allowable stress limit is for statically stressed vessels. This means that the number of stress cycles applied during the life of vessel does not exceed several thousands. For cyclic conditions these allowable stresses would have to be substantially reduced and preferably a fatigue analysis made. Usually, in service the operating loads.are raised gradually up to their maximum values and maintained for some time and they are not reapplied often enough to make a fatigue analysis necessary. 

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