Influence of stirrup ratio on vehicular impact resistance of double-column RC bridge piers

Abstract

Vehicular collision is a typical lateral consecutive impact process. Under such an impact process, reinforced concrete (RC) bridge piers commonly suffer shear failure or punching-shear breakage, which could further cause the collapse of the bridges, especially for the simply-supported double-column RC bridges. The current work experimentally and numerically investigates the influence of stirrup ratio on the lateral consecutive impact resistance of double-column RC bridge piers (DCBPs). Firstly, a scaled lateral consecutive impact test is conducted on three DCBP specimens (containing impacted pier, adjacent pier and bent cap) to examine the influence of stirrup ratio on the dynamic behaviors at component level. Then, finite element (FE) models of the impact test are established and validated against the experimental results. Finally, refined numerical simulations of light, medium and heavy trucks colliding with a prototype simply-supported double-column RC bridge are performed at structural level to analyze the influence of stirrup ratio on dynamic shear capacity and deformation of the impacted RC piers, and anti-collapse performance of the bridges. The results derive that, (i) The impacted piers exhibit shear failure at the impact location, and the damage degree is significantly reduced with increasing stirrup ratio. However, the damage degree of adjacent piers and bent caps is not obviously influenced by the change of stirrup ratio; (ii) A higher stirrup ratio effectively achieves less stiffness degradation and smaller lateral deformation of the impacted piers under the first impact, that allows DCBPs to resist a higher second impact force; (iii) The deformation shape of the impacted piers is changed from the localized deformation to the global deformation with the increase of stirrup ratio, while such a variation does not occur to the adjacent piers; (iv) As the stirrup ratio increasing, the simply-supported double-column RC bridge can withstand a higher dynamic shear demand induced by vehicular collisions, and therefore decreases the global damage and collapse probability, especially when subjected to heavy truck collisions.