Creep and Shrinkage Deflections of RC Beams with Steel Fibers

Abstract

In this paper, two analytical approaches based on the effective modulus method (EMM) and the age‐adjusted effective modulus method (AEMM), are proposed for the prediction of deflections due to creep and shrinkage in reinforced‐concrete beams with a steel‐fiber concrete matrix under sustained loads. In the EMM‐based approach, the deflection due to creep is evaluated from an elastic analysis using a modulus of elasticity that accounts for the reduced creep coefficient in steel‐fiber concrete, while the deflection due to shrinkage is analyzed using the equivalent tensile‐force method, which accounts for the reduced shrinkage strains in the steel‐fiber concrete. The AEMM‐based approach considers the aging of steel‐fiber concrete and involves a simultaneous linear‐elastic analysis for deflections due to creep and shrinkage using an age‐adjusted effective modulus of elasticity. Tests on 12 SFRC beams as well as on the material properties were carried out. The proposed methods, using creep coefficients and shrinkage strains obtained from compressive creep test and free‐shrinkage test on steel‐fiber concrete, respectively, are found to predict the creep and shrinkage deflections with very good accuracy.