Fatigue Strength of Prestressed Composite Beams. Final Report

摘要

Previous fatigue test data for 700 strands, 99 specimens with shear studs, and 267 cover plate ends were analyzed to determine the base line for the present study. Eleven prestressed composite beams were tested in fatigue, and two fatigue cracked beams were tested for static strength. No fatigue failures were observed in the strands and shear studs because the stress ranges in these details were lower than the applicable fatigue limits. It was found that new prestressed composite beams with cover plates tested under zero-to-tension stress cycles had Category D fatigue strength, whereas new prestressed composite beams tested under full stress reversal had Category C fatigue strength. Fatigue cracked beams can be repaired by prestressing. Depending on the level of compression that is introduced by prestressing, details welded to the steel beams may become fatigue-proof. The measured ultimate strength of cracked composite beams was accurately predicted with simple models.