Mechanical performance of bonded prestressed concrete beam with steel corrosion under partial heating condition

With the development of infrastructure, a large number of concrete bridges are corroded and aged under adverse environment, and the study of the disaster damage mechanism of corroded bridge structure is of great significance to the operational safety of bridge structure. To investigate the high-temperature mechanical performance of damaged bridge with steel corrosion under partial heating conditions, ten bonded prestressed concrete (BPC) beams were designed in this study. Two specimens in the control group were loaded at normal temperature, and the test variable was initial stress in the prestressing strand; eight specimens in the test group were loaded at high temperature, and the test variables were steel corrosion, initial stress in the prestressing strand and initial load. First, based on the electrochemical principle, four prestressed concrete beams were subjected to accelerated steel corrosion treatment, and then eight prestressed concrete beams (four corroded and four uncorroded) were subjected to three-sided fire tests at mid-span using a composite high-temperature test furnace. Finally, the numerical method was used to simulate and analyze the locally heated prestressed concrete beams. The experimental results show that under local heat conditions, the load capacity of prestressed concrete beams will be significantly reduced, with a decrease of about 11.3%～14.9%. Concrete cracking caused by steel corrosion can adversely affect the fire resistance of prestressed concrete beams in two main ways. 1) The prestress increment of corroded specimens is larger under the same test conditions. 2) Under local heating condition, the bearing capacity of corroded specimens decreases more significantly, about 19.4%～21.9%. Increasing the initial stress of prestressed tendons can reduce the creep deformation of prestressed concrete beams under local heating. Under the action of local high temperature, the prestressed concrete beam is more sensitive to the initial load. When the initial load value of the specimen increases by 20%, the three-point displacement increases by about 60%. And the results of the study can provide a theoretical basis for the fire protection design of corroded bridges. © 2024, Central South University Press. All rights reserved.