Partially Prestressed Beams under Random‐Amplitude Fatigue Loading

Abstract

The main objective of this investigation is to evaluate the behavior of partially prestressed concrete beams subjected to random‐amplitude fatigue loading and to better understand the parameters that control their fatigue life. The experimental portion of the program described here includes the testing of six control beams tested to failure under monotonically increasing load, and 10 beams tested in fatigue. The peak load in the fatigue tests was selected to simulate the frequency distribution of truck loadings on bridges. Test measurements included deflections, crack widths, curvatures, and strains in the reinforcing and prestressing steels, as well as the increases of these measures during cyclic loading to failure. It was found that random‐amplitude fatigue loading is more severe than constant‐amplitude fatigue loading and that the combination of stress range in the prestressing steel and crack width range in the concrete may be particularly damaging in fatigue. It is also observed that shear failure under random‐amplitude fatigue loading may need further investigation.