Development Of Corrosion Fatigue Experimental System For Bridge Structure Environment/load Coupling

Long-term cyclical effects of various climatic environments cause corrosion of bridge structures,the bridge is subjected to random vibration loads such as wind,rain,earthquakes and vehicle loads.Under the coupling of time-varying service environment and random load,the bridge structure is more prone to corrosion fatigue damage.Natural corrosion test,replacement component test method and environmental accelerated corrosion test are often used to study the corrosion fatigue of bridge structures.In order to achieve the use of indoor accelerated corrosion experiments to predict the actual life of the bridge,This paper relies on the support of the National Natural Science Foundation’s major scientific research instrument development project ’Development of Structural Fatigue Experimental System in Complex Environment(Project Approval Number:11627802)" to develop the corrosion fatigue experimental system under bridge structure environment/load coupling.The main research contents and results are as follows:(1)This paper investigates the research status of experimental systems under environmental/load conditions at home and abroad,summarizes the research methods of corrosion fatigue,explores the corrosion mechanism of bridges,and statistics the environmental factors of bridge structure corrosion in service environment.(2)A large-scale variable space environment simulation system was developed.Combined with the service environment of the bridge structure and the environmental test of the electronic and electrical products and the environmental test of the military equipment laboratory,the environmental parameters of the large-scale variable space environment simulation system were designed.The system consists of A,B,C,D and E environmental boxes.Each environmental box can be used alone,and can achieve a random combination of hot and humid environment,acid rain environment,salt spray environment,freeze-thaw environment and carbonization environment.(3)Dynamic and static multi-function loading system was developed.The dynamic and static loading system consists of four parts:a large tonnage multi-function servo static and dynamic loading device,a self-balancing reaction frame,a multi-point mobile multifunction loading device,and an experimental data acquisition system The random load spectrum is compiled,and the experimental load spectrum is imported into the control system to realize the loading of random loads.(4)A non-contact non-destructive testing system has been developed.There are two main components:hardware systems and software systems.The hardware system mainly includes industrial CCD camera,industrial lens,light source,bracket,trigger collector and computer.The software system is mainly image analysis software.In various extreme environments,the system measures the full-field three-dimensional coordinates,displacements,strains,and cracks of the structure.(5)An accelerated test method in which a single environment interacts with loads is discussed.The system can carry out accelerated experiments under the joint action of salt spray environment,freeze-thaw environment,constant humid heat environment,alternating damp heat,acid rain corrosion environment,carbonized corrosion environment and static load,dynamic load and random load An accelerated test method for coupling multiple environments with static,dynamic and random loads is proposed.(6)The bearing capacity of reinforced concrete beams is studied under the coupling of load and hot and humid environment.The coupling of the load and the hot and humid environment accelerates the deterioration of the test beam,resulting in a decrease in the ultimate load carrying capacity.