Cyclic Behavior of Rectangular Bridge Piers Subjected to the Coupling Effects of Chloride Corrosion and Bidirectional Loading

The degradation of seismic performance for RC bridge piers induced by chloride corrosion has previously been studied by treating the earthquake as a unilateral cyclic loading. Such studies do not consider the true response of the pier under the joint effect of corrosion damage and real multi-dimensional earthquake action. Thus, in the present study, the cyclic behavior of rectangular bridge piers subjected to the coupling effects of chloride corrosion and bidirectional loading was numerically investigated. First, the corrosion-induced deterioration of material mechanical properties is introduced. Second, the numerical model of two corroded piers is built and validated with the test results in the literature. Then, the time-dependent biaxial seismic performance of a rectangular bridge pier under the circular-shaped (CS) biaxial displacement pattern, square-shaped (SS) biaxial displacement pattern, uniaxial displacement in the X-direction (UX) pattern, and uniaxial displacement in the Y-direction (UY) pattern is analyzed using the validated model. The simulation results conclude that the trajectory of biaxial loading paths and corrosion levels significantly influence the peak force, deformation capacity, and dissipated energy of the piers. The biaxial loading path effect for the corrosive pier includes two stages with different biaxial force trajectory characteristics. Compared with the uncorroded pier, the corrosion level of 13.7% and biaxial loading induces up to a 40% reduction in strength and a 54% decrease in the residual ultimate displacement of the corroded pier. For the same corrosion degree, the dissipated energy under the SS biaxial displacement path is the largest among the four loading paths.

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