Experimental and Numerical Study on Axial Capacity of FRP-Rehabilitated Postblast RC Bridge Pier

Abstract

The aim in this study is to experimentally and numerically evaluate the effectiveness of the fiber-reinforced polymer (FRP) rehabilitation technique on postblast piers. Firstly, contact explosion, carbon FRP (CFRP) rehabilitation, and axial compression tests were successively conducted on half-scale RC pier specimens. The incident overpressure time histories and damage profiles of specimens in the explosion test, as well as the axial force–displacement curves, strain time histories of FRP, and specimen damage modes in the axial compression test were recorded. Secondly, a finite-element (FE) analysis approach was proposed and experimentally validated to reproduce the blast wave–pier interactions and dynamic behaviors of RC piers under explosions, as well as the axial compressive performance of the intact, unrehabilitated, and FRP-rehabilitated RC piers. Furthermore, three typical explosion threats specified by the Federal Emergency Management Agency were selected, and the damage profiles and residual axial capacities of the seismically designed prototype bridge piers were further examined. An FRP rehabilitation scheme, covering FRP type, rehabilitation height, and number of rehabilitation layers, for restoring the axial capacities of postblast prototype piers is recommended. It indicates the following. (1) FRP rehabilitation effectively improves the axial capacity and ductility of postblast piers, but slightly affects the axial stiffness. (2) The residual axial capacities of the presented prototype piers reduced to 92% and 58% of the intact value under contact explosion from a suicide belt or suicide vest, and increased to 99% and 84% after two-layer CFRP rehabilitation. (3) Compared with glass FRP and aramid FRP, CFRP rehabilitation along the overall pier height is more strongly recommended. (4) Increasing the number of rehabilitation layers to four could prominently improve the axial capacity. This work could provide a supportive reference on the FRP rehabilitation of a RC bridge pier after explosions.