Horizontal bearing characteristic and seismic fragility analysis of CFRP composite pipe piles subject to chloride corrosion

Abstract

This paper studies the time-dependent horizontal bearing characteristic and seismic fragility analysis of carbon fiber reinforced polymers (CFRP) composite pipe piles under chloride corrosion. A diffusion model of chloride ions in CFRP composite pipe piles is established based on Fick's second law, allowing for the prediction of corrosion initiation time of CFRP composite pipe piles. The flexural stiffness of composite pipe piles for different CFRP replacement ratios is calculated, and the time-dependent horizontal bearing capacity of CFRP composite pipe pile is calculated using the finite difference method. Considering the uncertainties of structural modeling and earthquake waves, an analysis is conducted to study the effect of earthquakes on piles with different CFRP replacement ratios at various service times. The seismic fragility curves are then derived. The research results show that with the increase of service time, the flexural stiffness of CFRP composite pipe piles decreases. Moreover, higher CFRP replacement ratios result in reduced loss of pile bending stiffness and greater stability of the flexural bearing capacity. As the service time increases, the failure probability of composite pipe piles under seismic action exhibits a smaller increase, particularly for higher CFRP replacement ratios, thereby resulting in a lower loss of seismic performance.