Nonlinear Analysis of Compressed Concrete Elements Reinforced with FRP Bars

Area of Science:

• Civil Engineering
• Materials Science

Background:

• Fiber reinforced polymer (FRP) bars are increasingly used in concrete flexural elements.
• Limited data exists on the performance of FRP bars in concrete elements under axial compression.
• The application of FRP bars as main reinforcement in compressed elements remains controversial due to insufficient research.

Purpose of the Study:

• To investigate the performance of concrete elements reinforced with basalt FRP, glass FRP, and steel under axial compression.
• To address the knowledge gap regarding the use of FRP bars in compressed concrete elements.
• To provide data for the establishment of design rules for FRP-reinforced concrete.

Main Methods:

• Theoretical analyses based on stress distribution in the cross-section.
• Finite element method (FEM) analysis, including nonlinear analysis.
• Comparison of theoretical calculations with experimental results for basalt FRP, glass FRP, and steel-reinforced concrete elements.

Main Results:

• A good agreement was achieved between calculated failure loads and experimental results.
• Non-metallic bars (basalt FRP, glass FRP) experienced stress values significantly lower than their compressive strength (around 100 MPa).
• Nonlinear FEM analysis proved effective in predicting maximum load values and damage zones.

Conclusions:

• The potential negative influence of FRP reinforcement on the compressive capacity of concrete elements must be considered.
• While FRP bars exhibit low stress, their impact on overall element capacity requires careful evaluation.
• The findings contribute to a better understanding of FRP-reinforced concrete under compression, aiding in future design rule development.