International Concrete Abstracts Portal

Title: Generalized Nonlinear Moment–Curvature Model for the Mechanical Degradation of R/SFRC Beams Under Flexural Fatigue Loading

Author(s): Mobasher

Publication: Web Session

Volume: ws_F24_Mobasher2.pdf

Issue:

Appears on pages(s):

Keywords:

DOI:

Date: 11/3/2024

Abstract:
The present research investigates the fatigue behavior of hybrid reinforced concrete beams, composed of self-consolidating 60 MPa concrete with hooked-end steel fibers and conventional steel rebars. Fatigue tests were conducted under a continuous stress level corresponding to 80% of the steel yield strain, with loading frequencies of 6 Hz, and stress ratios of 0.3 and 0.1. The experimental results validated the proposed model, which incorporates constitutive relations for the steel fiber reinforced concrete and steel rebars. The approach used involves a trilinear model for tension, a perfectly plastic bilinear model for compression and steel, to characterize the moment-curvature relationship under static loading. This generalized model employs moment-curvature relationships derived from constitutive models with multilinear equations to predict the mechanical degradation of hybrid reinforced beams during flexural fatigue. Furthermore, the model aims to predict the fatigue life of structural beams, using experimental data to determine the evolution of steel strain and formulate an expression related to the steel strain variation in the rebars throughout the cycles. This relationship is crucial for evaluating curvature and stiffness loss under cyclic loading, which allows for the assessment of the serviceability range and prediction of the residual fatigue life for a given lifecycle and stress range.