Fatigue behavior of unbonded prestressed reactive powder concrete beams after creep

摘要

Failure modes of two kinds of unbonded prestressed reactive power concrete (UPRPC) beams were studied experimentally under static and fatigue loads, and compared. In the tests, deflections, crack widths, rebar strains, and beam strains were measured and analyzed. The fatigue test results show that the fatigue life of non-creeped beams is more than 2 million loading cycles and the creeped beam is damaged after 1.75 million loading cycles. The compression edge strain, mid-span deflection, and rebar strain are -814 mu xi, 7.6 mm, and 484 mu xi, respectively, for noncreeped UPRPC beams, and -1110 mu xi, 11.2 mm, and 1169 mu xi, respectively, for creeped UPRPC beams (it represents 1 x 10(-6)). These values are much smaller than the static load failure values. Considering the fatigue residual strain, fatigue elastic modulus degradation, and fatigue strength degradation, a simplified analysis method for a full fatigue process is proposed, which predicts values in good agreement with the measured results.