Title:
Rigorous Procedure for Calculating Deflections of
Fiber-Reinforced Polymer-Strengthened Reinforced Concrete Beams
Author(s):
Hasan Charkas, Hayder A. Rasheed, and Hani Melhem
Publication:
Structural Journal
Volume:
100
Issue:
4
Appears on pages(s):
529-539
Keywords:
deflection; flexural strength; reinforced concrete.
DOI:
10.14359/12662
Date:
7/1/2003
Abstract:
The use of externally bonded fiber-reinforced polymer (FRP) plates has been established as an effective means to strengthen reinforced concrete (RC) beams in flexure and shear. Few investigators have attempted to propose minor modifications to the original ACI empirical equation for estimating the effective moment of inertia of RC beams. Others used numerical analysis to generate such deflection computations. Alternatively, the present work develops a rigorous analytical procedure for calculating the deflection of simple beams at any load stage. The procedure assumes a trilinear moment-curvature response characterized by section flexural crack initiation, yielding, and ultimate capacity. This model incorporates some tension stiffening effects and assumes the section to be fully cracked only upon or near steel yielding. The curvature distribution is determined for uncracked, partially cracked, and postyielded regions. Closed form equations are developed for the case of four-point bending and uniformly distributed load. Comparisons with 22 experiments indicate the applicability of the procedure, especially for properly anchored plates. A parametric study is conducted to examine the relevance of the ACI original and modified equations for a wide range of geometric and material properties as well as different loading conditions.