Flexural behavior test of corroded prestressed concrete beams under chloride environment

In order to study the flexural capacity of corroded prestressed concrete beams under chloride environment, five pretensioned prestressed concrete beams were manufactured, and subjected to accelerated corrosion for 0 d, 7 d, 14 d, 28 d and 42 d by electrochemical method, then four points bending tests were carried out on all beams. The influence of different corrosion level on the natural frequency of prestressed concrete beams, the slip of steel strands, the structural deformation, crack propagation, failure mode and ultimate bearing capacity were researched. The results indicate that corrosion in chloride environment affects slightly the high-order frequency of prestressed concrete beams, and increases the first natural frequency of prestressed concrete beams. After 28 d, the corrosion cracks are large and part of the concrete falls off, the first natural frequency decreases rapidly. Slight corrosion has little effects on flexural behavior of prestressed concrete beams, and the flexural behavior decreases significantly with the increase of corrosion level. After 42 d corrosion, the ultimate deflection decreases by 18.7%, the flexural capacity decreases by 17.3%, and the ductility decreases by 19%. The slip rate between the corroded steel strand and concrete increases, and the ultimate slip value increases from 5 μm to 11.4 μm. Corrosion affects slightly the development of crack height, and promotes the expansion of crack width. After yielding, the cracking rate of bottom cracks increase from 0.0062 mm/kN to 0.0252 mm/kN. Based on the test, the loading process of corroded beam was simulated through finite element software ANSYS, the errors of ultimate load and ultimate slip value between the simulated value and the experimental value are less than 5% and 10%, respectively, the simulated values are in good agreement with the experimental data.