Behavior and design of eccentrically compressed
hybrid steel and GFRP reinforced concrete
columns at elevated temperature
Haitham Al-Thairy1,2
1Civil Engineering Department, College of
Engineering, University of Al-Qadisiyah,
Al-Diwaniyah, Iraq
2College of Engineering, University of
Warith Al-Anbiyaa, Karbala, Iraq
Correspondence
Haitham Al-Thairy, Civil Engineering
Department, College of Engineering,
University of Al-Qadisiyah,
Al-Diwaniyah, Iraq.
Email: haitham.althairy@qu.edu.iq
Abstract
This study presents analytical model for the analysis of hybrid (steel and fiber
reinforced polymers (FRP)) reinforced concrete (RC) columns at elevated temperature
under eccentric compressive loads. The bending moment resistance
of the (RC) columns at elevated temperature is formulated based on force
equilibrium and strain compatibility of the concrete column section under
combined bending moment and axial force. Deterioration the mechanical
properties of concrete, steel, and FRP bars due to the rise of temperature has
been taken into account using equations proposed by previous studies. Validating
the suggested model was carried out by comparing the analytical results
with corresponding experimental and numerical results in terms of axial loadlateral
displacement relationships, axial load-bending resistance interaction
diagrams, and failure modes. Validation results have shown the accuracy of
the suggested analytical model. A parametric study has also been conducted
using the proposed analytical model to investigate the effect of some parameters
on the axial load-bending resistance interaction diagrams of hybrid steel
and FRP-RC columns under elevated temperature. These parameters include
the effect of higher temperature values, the effect of reinforcement material,
and the effect of reinforcement configuration. Parametric study results have
revealed some interesting conclusions that may be implemented in the design
of hybrid RC columns at fire.
K E YWO R D S
elevated temperature, FRP bars, hybrid reinforcement, interaction diagrams, RC columns
1 | INTRODUCTION
1.1 | Review of literature
Over the past two decades, using fiber reinforced polymers
(FRP) bars in reinforced concrete industries has
highly increased due to the attractive mechanical characteristics
of FRP bars compared to the ordinary steel bars
such as the high strength-to-weight ratio and the
corrosion resistance. Therefore, a demand of the FRP
bars in design and construction of concrete structures has
been growing nowadays, particularly at harsh environments
such as marine structures, large span bridges, and
basement parking garages. However, FRP bars implicate
specific drawbacks which could limit the scope of implementation
in concrete design such as low modulus of
elasticity and low fire endurance compared to that of the
conventional steel bars. Consequently, using hybrid
Received: 1 September 2023 Revised: 1 February 2024 Accepted: 4 April 2024
DOI: 10.1002/suco.202300734
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