Prediction equation for maximum stress of concrete drainage pipelines subjected to various damages and complex service conditions

Abstract

Concrete drainage pipelines built in early China are seriously aged and in disrepair. Therefore, the methods that can be directly used to evaluate the service performances of such pipelines are urgently needed. In this study, 100 three-dimensional (3-D) refined finite element (FE) models of concrete drainage pipelines subjected to corrosion and void damages were established based on ABAQUS 6.14-1/Standard. First, the full-scale test data in the existing studies were used to verify the FE model. Then, 100 numerical analyses were performed on 9 dimensionless variables affecting the stress of the pipelines, among them, 70% were randomly selected as the training set, and 30% as the test set based on the Holdout cross-validation method. Finally, the maximum stress evaluation model for the concrete drainage pipelines subjected to damages and complex service conditions was successfully proposed based on multivariate nonlinear regression (MNR). The training and test results show that the proposed equation is capable of predicting the maximum stress of the pipeline with high accuracy (R2 = 0.96 and 0.97, respectively), and the prediction error is in normal distribution. Verification of the proposed equation shows that it has a high accuracy in predicting the effects of h, Ch, Cl, and Vl on the maximum stress of the pipelines, with the relative errors of 13.55%, 12.70%, 13.33%, and 18.94%, respectively. In particular, for traffic load, the relative error is only 4.97%. Additionally, the Spearman’s rank correlation coefficient of each variable was calculated and normalized to analyze the relative contribution of each variable to the pipeline maximum stress. The analyses show that the traffic load has the greatest effect on the pipeline stress, with a relative contribution percentage of 25.1%. Furthermore, the feasibility of the proposed equation in predicting the remaining life of pipelines is proved.