Link to the Latest: September 2021 Progress Report
Elastomeric polymers such as polyurea and polyurethane are nonlinear elastic materials with high tensile strength and strain capacity, adhesiveness, and resistance to permeability and environmental conditions. They have been used commercially as waterproofing and anti-blast coating for reinforced concrete components. While the elastomeric polymer is an interesting material with unique characteristics, there has been limited research on its potential structural applications. A number of research studies have shown the remarkable increase in flexural and shear strength of polyurea coated reinforced concrete beams. Further research is needed to explore the application of polyurea coating system as a new structural material in the bridge industry.
This project takes the first step of a long-term research vision to examine and investigate the innovative applications of elastomeric polymers and specifically polyurea coating in accelerated bridge construction. The focus of this project is on the application of elastomeric polymer coatings for design and retrofit of side bridge girders. There are three aspects that can be considered for this application: (i) enhancing the flexural and shear strength of the beam through the application of a spray coating, (ii) enhancing the weather resistivity, which is especially important for side beams, and most importantly, (iii) overheight vehicle collision impact resistance. This project only focuses on the flexural and shear strength of polyurea coated RC beams. This simple step is taken to start gaining experience and knowledge on this relatively new material, and incrementally examine other aspects of the applications and other potential applications through future funding opportunities. We plan for an experimental-analytical research effort, to develop simple phenomenological material models for the polyurea coating system and to investigate the potential cost vs. benefit of the coating in design and retrofit of side girders.
A Comprehensive literature review will be performed on the polyurea material and coating system for structural application, including the experimental results, numerical modeling, material models, etc.
A series of polyurea coupon samples will be tested under uniaxial cyclic loading scenarios to develop a phenomenological stress-strain and viscosity material model.
Task 3 – Material Model Implementation and FE Numerical Studies
The phenomenological material model will be implemented in a FE simulation platform (e.g., LS DYNA) and will be used to model the response behavior of coated RC beam specimens tested in the literature. The analysis results will be compared with the experimental counterparts provided in the literature to validate the modeling techniques. A model calibration method based on Bayesian inference will be utilized for model calibration and reducing the discrepancies between simulation and experimental results.
Task 4 – Parametric Studies & Economic Analysis
With the calibrated FE model and modeling techniques developed in Task 3, a parametric study will be performed to examine the increase in flexural and shear strength capacity of bridge girder beams due to the polyurea coating. The cost of polyurea system vs. the increase in strength will be compared with similar solutions (e.g., FRP) to provide an estimate of the economic feasibility of the new material. This step will pave the way to investigate the other potential benefits of polyurea system for side girder design and retrofit.
Principal Investigator: Dr. Hamed Ebrahimian
Co-Principal Investigator: Dr. Mohamed Moustafa
Research Assistant: Pawan Acharya
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