Rheological Relaxation of OSB Beams Reinforced with CFRP Composites.

Area of Science:

• Materials Science
• Civil Engineering
• Structural Engineering

Background:

• Wood-based materials like Oriented Strand Board (OSB) are extensively used in construction.
• Understanding the rheological properties of OSB and composite reinforcements is crucial for structural integrity.
• The relaxation behavior of these materials under load is complex and requires detailed investigation.

Purpose of the Study:

• To experimentally and analytically investigate the relaxation problem of OSB beams.
• To evaluate the effect of Carbon Fiber Reinforced Polymer (CFRP) tape reinforcement on the relaxation behavior of OSB beams.
• To develop and validate rheological models for predicting the long-term performance of reinforced OSB.

Main Methods:

• A 10-day relaxation test was conducted on OSB beams, both unreinforced and reinforced with CFRP tape, using a four-point bending test.
• Five different bending levels were applied, and the reduction in loading force was measured.
• A five-parameter rheological model, utilizing Laplace transforms, was employed to describe the material's behavior, with parameters derived from experimental data.

Main Results:

• A high correlation was achieved between experimental and theoretical results for both unreinforced and CFRP-reinforced OSB beams.
• The CFRP-reinforced beam was modeled as a system combining a viscoelastic OSB element and an elastic CFRP element.
• Significant stress redistribution was observed in the reinforced beams during relaxation, leading to approximately 63% higher stiffness and proportionally higher load capacity.

Conclusions:

• The developed rheological models accurately predict the relaxation behavior of OSB beams.
• CFRP reinforcement substantially enhances the stiffness and load-bearing capacity of OSB beams.
• The study provides valuable insights into the long-term performance of composite wood-based structural elements.