EXPERIMENTAL STUDY OF FATIGUE BEHAVIOR OF THE PRESTRESSED CONCRETE BEAMS WITH PRETENSIONED BENT-UP TENDONS

To research the fatigue behavior of the prestressed concrete beams with pretensioned bent-up tendons，2 prestressed concrete beams ( span = 7. 5 m) with pretensioned bent-up tendons were designed and made，and the fatigue behavior test and the last statical test after their fatigue behavior test were carried out under different upperlimit and lower-limit bending moment． It was proved by the experimental result that the concrete strain basically agreed with the plane cross-section assumption in the whole experimental process，the residual bearing capacity was not affected by the loading history，the bearing capacity and the crack width still could be calculated by the formulas stipulated in the code，and the fatigue behavior of the beam was excellent． The formulas where compressive strain of the beam top，strand，the fatigue stress amplitude of nonprestressed reinforcement and fatigue stress ratio were changed with the loading cycles were fitted，and it can be referenced for developing numerical analysis software of the behavior of the prestressed concrete beams with pretensioned bent-up tendons and the fatigue behavior analysis in the engineering application．