Title: Reliability-Based Code Development for CFRP-Strengthened Circular Reinforced Concrete Columns

Author(s): Juscelina R. Ferreira, Peterson A. Quadros, Sofia M.C. Diniz

Publication: Structural Journal

Volume:

Issue:

Appears on pages(s):

Keywords: CFRP confinement, circular cross-sections, design codes, existing structures, reliability index, reinforced concrete, short columns, strengthening

DOI: 10.14359/51740490

Date: 1/29/2024

Abstract:
Concrete confinement using fiber-reinforced polymers (FRP) has been vastly used for strengthening reinforced concrete (RC) columns. The strengthening of RC columns belongs to the realm of existing structures, which has been recognized as distinct from the design of new structures. Code development efforts for strengthening RC columns should follow a reliability-based framework similar to the one used in code development for new structures. In this process, a number of additional issues arise: the mechanical model of FRP confinement representing existing RC columns, the statistical description of the design variables, and the target reliability to be attained. In this study, the reliability levels of 288 axially-loaded, FRP-RC short columns of circular cross-sections, strengthened according to ACI 440 guidelines are assessed. Monte Carlo simulation is used in the probabilistic description of column strength and computation of the probability of failure. An FRP-confinement model that explicitly accounts for the presence of transversal steel and attendant model errors associated with the estimation of ultimate stress and ultimate strain is used in the computation of the FRP-RC column capacity. The values of the reliability index are in the range 3.92 - 4.61, satisfying the target reliability suggested for both new and existing structures. The research findings presented herein provide further support for the efforts of ACI 440 committee in the development of standards related to the FRP strengthening of RC columns.