Seismic Vulnerability Analysis of Multi-Age Buried Steel Pipes in an Acidic Soil Environment

In an acidic soil environment, the seismic performance of the buried steel pipes will obviously decrease with increasing service life. To study the seismic performance of the multi-age buried pipes in an acidic soil environment, the accelerated artificial corrosion test and the steel tensile failure test were performed. The relationships between yield strength, maximum strength, modulus of elasticity, elongation and weight loss rate were established. The variation laws of mechanical properties and size of steel pipes with increasing service life were obtained based on the general corrosion model, in order to establish the time-varying constitutive model. Based on the ANSYS finite element software, finite element models were established considering the deterioration of the geometric dimensions and mechanical properties of the corroded steel pipes under acidic soil conditions. Using the incremental dynamic analysis method and the cloud map method, a probabilistic model of seismic demand was established describing ground motion intensity parameters and structural demand parameters. Combined with the division of pipes damage states and the determination of the maximum damage value in the sense of probability, the seismic vulnerability analysis of buried steel pipes was performed, thus establishing the time-varying seismic analytical vulnerability models of buried steel pipes with different service ages, considering the degradation of corrosion durability. The relationship between the pipes damage index and the ground motion intensity index was characterized. In addition, the seismic vulnerability curve of buried multi-age steel pipes with different diameters was given. The results showed that, with the increasing age of service in acidic soil, the geometric dimensions and the mechanical properties of buried steel pipes were continuously reduced, and the probability of different states of damage caused by earthquakes increased in different amplitudes. Under the same conditions, with the increase in the diameter of the pipes, the probability of different states of damage from the earthquake was reduced to some extent. © 2020, Editorial Board of Journal of Tianjin University(Science and Technology). All right reserved.