Blast Response and Damage Mechanism of Prefabricated Segmental RC Bridge Piers

摘要

Public transportation is vulnerable to terrorist attacks due to its accessibility, especially bridges in the highway and urban systems under blast loading. Prefabricated segmental reinforced concrete (PSRC) piers are one of the popular constructional elements in accelerated bridge construction projects in recent years. Therefore, it is necessary to investigate the dynamic response and damage mechanism of the PSRC pier under close-in blast loading. In this paper, a blast experiment on one conventional square reinforced concrete (RC) pier and one square PSRC pier was conducted in a bottom explosion experiment. Based on the test results, the numerical models were developed and calibrated according to the theoretical prestressing force, experimental displacement history, residual displacement, and failure height. The validated model could be used to reliably and accurately analyze the blast response and the damage mechanism of PSRC piers. Results showed that the PSRC pier had a localized segmental failure in the bottom explosion zone and other segments had vertical cracks and concrete extrusion above the explosion zone resulting from the concrete squeezing stress, and the segmental interface could block the stress flow propagation; the monolithic pier had massive transversal cracks on the upper parts due to the vertical propagation of stress flow; the PSRC pier had small relative segmental slips and rotations with a restored movement due to the restraint of prestressing force under a scaled distance of 0.6 m/kg(1/3), while it had large localized slips with irreversible displacements without any restraint of prestressing force under a scaled distance of 0.4 m/kg(1/3); the PSRC pier preferentially experienced localized segmental shear failure under surface blast, while it had an overall flexural failure under air burst; and the explosive energy of the PSRC pier was mainly dissipated by the deformation and spalling of concrete.