Structural Design And Test Research Of Electrically Isolated Prestressing Corrosion Protection System

Since the development of prestressing technology,the corrosion of prestressed tendons has caused huge economic losses and seriously endangered people’s safety.The electrically isolated protection technology proposed abroad achieves effective corrosion protection by completely encapsulating prestressed tendons,simultaneously with corrosion monitoring.In order to improve the corrosion protection level of the existing prestressed anchorage system,based on the method of electrically isolated protection,the thesis designs an electrically isolated prestressed corrosion protection system by improving and optimizing the structure of the conventional anchorage system,and research the leak tightness and electrically isolated performance of the electrically isolated corrosion protection system through experiments,the main work is as follows:(1)Research the corrosion mechanism of prestressed tendons,analyze the types and causes of prestressed tendon corrosion,then summarize the key corrosion media that cause prestressed tendon corrosion and the areas that need to be protected inside the prestressed concrete structure,provide a theoretical basis for the design of electrically isolated prestressing corrosion protection system.(2)Design and research structure of electrically isolated prestressed corrosion protection system,put forward the design requirements and formulated the design plan based on the requirements of corrosion protection,insulation,sealing and mechanical properties,and based on the structure of the conventional anchorage system,designed protective components for the areas where the corrosion media often invades.The components include: protection cap,isolation plate,plastic trumpet,and duct sealing connector.The three-dimensional model of all components is established in Solidworks,and the static analysis of the key component protective cover is carried out using ANSYS Workbench software.According to the simulation results optimize the component structure,and finally,the three-dimensional model assembly and sample test assembly of the electrically isolated corrosion protection system were completed.(3)Performance testing experiments were carried out for key components and overall assemblies.Among them,a compression test was carried out on a single protective cover component.The test showed that the oil pressure that the protective cap can resist exceeds 1.5MPa,which meets the engineering requirements and verifies the rationality of the previous finite element analysis results;the key sealing assembly in the system is tested.The positive pressure test and negative pressure test were carried out,and the assembly did not leak or permeate under the air pressure of 0.5bar and-0.5bar maintained for 30 minutes,which verified that the leak tightness of the designed system structure met the requirements;the overall assembly of the system was tested 28 days of electrical isolation monitoring test,the resistance value between prestressed tendons and steel bars in the monitoring period is greater than 15 kΩ,which meets the requirements of fib bulletin 75,and verifies that the electrically isolated performance of the designed system meets the requirements,and finally shows that the structure designed in the thesis has reached electrically isolated protection technology requirements.