The Seismic Performance And Vulnerability Research Of Corroded Steel Frame Structure In Acidic Air Environment

The steel structure engineering which exposed to the air will easily corroded with the corrosive medium due to its chemical properties. Corrosion will make the structure increase the risk probability of accident and threaten people’s life and property safety. In practical engineering applications, the corrosion causes catastrophic accidents commonly, and also very serious. Especially in acid atmosphere, the bearing specimens extremely easily happen brittle failure without signs in the welded steel structure and the steel structure in high stress state, it will endanger the safety of life. It makes the serve condition of steel structure more and more serious and affect the promotion of steel structure.Based on the research content of the National Key Technology R&D Program project, “The key technology research and demonstration of earthquake damage evaluation and simulation of urban multi-age building”(2013BAJ08B03), combined with experimental study and theoretical analysis, this paper conducted some research on steel structure in acid environment from the aspects of material and structure.(1)Steel material specimens and frame structure specimens were conducted spraying compound artificial cycle corrosion experiment, then derust the corrosion of material specimens.what’s more, the derusted specimens were conducted tensile experiment. For further research on relationship between the basic mechanical performance indices of steel and weight loss rate, this paper analyzed the experiment data of material tensile. By linear fitting and the numerical test, the relationship between the basic mechanical performance indices of steel and weight loss rate was built.(2)For the research on the degradation rule of the bearing capacity, stiffness,energy dissipation capacity of plane steel frame structure with the corrosion degreedeepen.Four plane steel frames were conducted the experiment of low cyclic loading.The results illustrated that buckling deformation occurred in all specimens, while the development rule of stress deformation and failure pattern were basically identical. The hysteresis curves of plane steel structure with different corrosion degree under low cyclic loading presented spindle shape without pinch phenomenon which indicated that steel structures have good ductility and energy dissipating capacity. As the corrosion getting more serious, the structures’ bearing capacity, stiffness, ductility and energy dissipating capacity dropped down correspondingly.(3)Based on the experimental research, plane steel frames with various corrosion degree are analyzed by numerical method using the finite element analysis software ABAQUS. Compared the simulation results with the experiment, the modeling method,material and element parameters and failure criterion in this paper are reasonable.(4)Combined with the material performance experiment results in acid atmospheric environment and based on the finite element analysis software ABAQUS, four different aged braced steel frame structure models were established. Then the incremental dynamic analysis is conducted which seismic demand measure is the whole structural damage index. And vulnerability analysis is conducted in order to investigate the law of maximum inter-story drift and the change of whole structure damage with different aged structures. The conclusions can be drawn that the drift and damage value are dramatically increasing under the rare earthquake. The damage status are in medium destruction or even collapse from lightly destruction. The seismic vulnerability curve shows that with the increase of structure age, the probability beyond a certain structure failure limit state gradually increases at the same seismic intensity.