Performance of UHPC bridge piers subjected to heavy vehicle collisions and probability analysis of damage level

Abstract

Heavy vehicle collisions have been reported as one of the major causes of normal concrete (NC) bridge pier failure due to its low crashworthiness. Ultra-high performance concrete (UHPC), which has been demonstrated as a promising engineering material to resist high strain rate loadings, is deemed as an alternative material to improve the collision performance of bridge piers that would be impacted by heavy vehicles. In this study, the performance of the UHPC pier subjected to heavy vehicle collisions is investigated by using the finite element (FE) modelling approach. Firstly, the damage and energy absorption characteristics of NC and UHPC piers are comparatively studied. The results show that the NC pier is dominated by plastic failure, whereas the UHPC pier essentially presents brittle damage. The kinetic energy of the vehicle is mainly dissipated by the steel reinforcement for UHPC piers whereas by the concrete for NC piers. Then, a comprehensive parametric analysis, with respect to the vehicle weight and velocity, pier diameter, and longitudinal and transverse reinforcement ratios, is performed to investigate the impact performance of UHPC piers. An analysis of the Pearson correlation coefficient for the involved parameters shows that the vehicle weight and velocity are key influential parameters to the peak impact force. Finally, to facilitate the evaluation of the bridge column subjected to heavy vehicle collisions, three regression surrogate models, SVR (support vector regression), kriging, and RBF (radial basis function), are established to predict the equivalent static force (ESF) of the peak impact force on UHPC piers with promising accuracy. Among the presented five damage levels, the probabilities of slight and moderate damages are remarkably larger when UHPC piers are impacted by heavy vehicles. This study can provide guidance for the revision of AASHTO and future engineering practices with considering UHPC piers subjected to heavy vehicle collisions.