Shaking Table Test On The Seismic Performance Of Nonuniform Corroded Bridge Pier Of Coastal Bridge

As an important component of transportation system, the bridge structure has more and more influence on people’s daily life. The seismic performance of bridge during its service period has been paid more and more attention by the researchers. Especially for the coastal bridges and cross-strait bridges, the corrosion caused by chloride ions is easier to arise because they are influenced by the harsh environment of damp air and seawater in the long-term service period. Generally, the corrosion of the coastal bridge piers can be divided into submerged zone, splash and tidal zone, and atmospheric zone according to the position of waterline. Because of wetting-drying cycle of seawater, enough sunlight and oxygen, the splash and tidal zone sustains more serious corrosion damage caused by chloride ions compared to the other corrosion zones. The corrosion of reinforced concrete structure would induce significant degradation of the material properties, consequently affects the seismic performance of structures. Aiming at the seismic performance of corroded coastal bridge pier, shaking table test is conducted in this study considering the combination effects of corrosion and earthquake hazard. Two corroded bridge piers with different corrosion level and one sound bridge pier are employed for the shaking table test in this study to analyses the dynamic response, seismic performance and failure mechanism of the structures under earthquake excitation.The main content of this thesis includes:(1) Theoretically investigation of corrosion mechanism for coastal bridge piers in the environment with chloride ions. Through the study on the chloride pentration pattern and the corrosion mechanism of reinforced concrete structure in the marine environment, and the comparison of several accelerating corrosion methods, it provides to use the electrochemistry accelerated corrosion method for the test specimens. Furthermore, the electricity accelerated corrosion period was calculated using Faraday’s laws of electrolysis.(2) Finish the previous preparation of the shaking table test, including the specimen design, pouring and curing of concrete, and corrosion of piers. Taking a practical engineering as the prototype structure, three bridge piers were designed referring to current national specifications, the conditions of the laboratory and the similarity criterion. Among them, two piers were corroded with accelerated corrosion method, and the corrosion ratios of the longtidudinal reinforcement were 5% and 10%, respectively.(3) Finish the designing scheme of shaking table test and carry out the shaking table test. The data was obtained after the shaking table test of 1 sound bridge pier and 2 corroded bridge piers and analyzed in aspects such as acceleration responses, displacement responses, dynamic amplification factor, natural period of vibration, damping ratio, displacement ductility factor and structural energy dissipation, etc. The experimental results show that the corroded bridge piers don’t perform as well as the sound bridge pier. The serious corrosion condition will lead to severe performance deterioration of piers.