Probability analysis of web cracking of corroded prestressed concrete box-girder bridges considering aleatory and epistemic uncertainties

摘要

Reasonable assessment of web cracking probability is essential to ensure the service performance of corroded prestressed concrete (PC) bridges. In this paper, a time-dependent prediction model of effective prestress for different prestress tensioning techniques and a corrosion propagation model are established. Meanwhile, an assessment approach of web cracking probability considering both aleatory and epistemic uncertainties is proposed. The case analysis results show that the doubled-tensioned prestress technique is obviously more effective in decreasing the web cracking probability than the traditional prestress tensioning technique. The existing probabilistic method that only considers the aleatory uncertainty may greatly underestimate the probability of web cracking. In comparison, the fastest time to reach the threshold value of web cracking probability when considering the epistemic uncertainty is over 11% earlier than that of using the existing methods. Additionally, the epistemic uncertainty of the chloride diffusion coefficient among the selected corrosion parameters has a most significant impact on the probability of web cracking. Therefore, the epistemic uncertainty of corrosion parameters, especially for the chloride diffusion coefficient, should be minimized as much as possible in this assessment process.