Title: Chaos Expansion for Long-Term Behavior of Carbon Fiber- Reinforced Polymer-Strengthened Reinforced Concrete Beams

Author(s): David Micnhimer and Yail J. Kim

Publication: Structural Journal

Volume: 117

Issue: 2

Appears on pages(s): 105-116

Keywords: carbon fiber-reinforced polymer (CFRP); long-term; modeling; polynomial chaos expansion; rehabilitation; strengthening

DOI: 10.14359/51716805

Date: 3/1/2020

Abstract:
This paper presents a robust mathematical model to predict the long-term behavior of reinforced concrete beams strengthened with carbon fiber-reinforced polymer (CFRP) sheets. The model is constructed using the theory of Polynomial Chaos Expansion (PCE) in conjunction with the adjusted effective modulus method. The formulation of PCE is composed of quadrature rules, variable transformations, and solution algorithms, including a step-by-step implementation procedure. After verifying the modeling approach against experimental beams taken from literature, a benchmark beam is designed and used for parametric investigations in order to understand the effects of various attributes on the strengthened beam subjected to sustained loads for up to 4000 days. The creep and shrinkage of the concrete appreciably develop with time, whereas the macroscopic behavior of CFRP is relatively insusceptible. The sectional response of the beam alters owing to the increased concrete strain and stabilizes as the amount of compression steel rises. The debonding failure of CFRP is not noticed when the beam is loaded up to 50% of its flexural capacity. The efficacy of CFRP-strengthening is substantiated through reducing steel stresses and long-term deflections, which are particularly noticeable when the beam cracks.