Deformability of Reinforced Concrete Hollow Columns Confined with CFRP

A large number of reinforced concrete (RC) bridges built in Europe between the 1950s and the 1970s are characterized by hollow section piers. Many of them are now in need of a seismic upgrade to improve their response under earthquake. To study the behavior of rectangular hollow cross sections subjected to combined axial load and bending, a total of seven 1:5 scaled specimens has been tested at the University of Naples Federico II. Tested specimens have external dimension of the section 14.17 in. (360 mm), wall thickness of 2.36 in. (60 mm), and height of 4.27 ft. (1.30 m) representing, in reduced scale, typical square hollow bridge piers. The paper discusses the outcomes of the performed tests focusing on the analysis of crosssection curvature, member deformability, specific energy, and model restraints. A first application of a refined method under development is presented to predict the behavior of unstrengthened specimens.