Effect of Load Cycling, FRP Jackets, and Lap-Splicing of Longitudinal Bars on the Effective Stiffness and Ultimate Deformation of Flexure-Controlled RC Members

Abstract

Practical models for the deformations of flexure-controlled reinforced concrete (RC) members at flexural yielding and at ultimate conditions and for their secant-to-yield-point stiffness were developed using a database of thousands of tests. They apply to monotonic or cyclic lateral loading and seamlessly cover beams; rectangular columns or walls; members with circular, T-, H-, U-, or box sections; conforming or not to seismic design codes; with continuous or lap-spliced bars; and with fiber reinforced polymer (FRP) wrapping or without. Empirical models for the ultimate deformation supplement a physical model based on curvatures and on a plastic hinge length. A procedure to identify the likely failure mode is proposed and applied to a larger database including shear-critical test specimens.