Assessment of Residual Load Capacity of ASR Affected Prestressed Concrete Structures
- Publication Type:
- Thesis
- Issue Date:
- 2023
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Alkali silica reaction (ASR) is a widespread issue that damages concrete structures globally, affecting their durability and functionality. While recent research has examined ASR's impact on reinforced concrete beams, the influence of prestressed loads on ASR-affected structures remains poorly understood.
The aim of this research program was to assess the remaining load capacity of prestressed concrete beams affected by ASR. A laboratory investigation was conducted using six full-scale prestressed concrete beams and two reinforced beams, constructed with both reactive and non-reactive aggregates. Cylinders were tested at various stages to assess compressive strength, splitting tensile strength, and dynamic modulus. During an accelerated ASR conditioning period, the expansion of plain concrete prisms and the strain in reinforcing and prestressing bars were continuously monitored. After nine months of conditioning, flexural and shear loading tests were performed on the reinforced and prestressed beams.
Results showed a significant reduction in the compressive strength, splitting tensile strength, and dynamic modulus of the cylinders after ASR cracking. Surprisingly, the reactive prestressed beams maintained their flexural load-carrying capacity, unlike their non-reactive counterparts.
An artificial intelligence model utilizing artificial neural networks (ANN) was proposed to accurately predict the elastic modulus of damaged concrete, as ASR significantly affects elasticity. Additionally, a constitutive model was proposed to account for factors such as alkali/silica concentration, aggregate size, externally applied stress, and ambient temperature's impact on ASR expansion.
Lastly, a nonlinear analysis of ASR-affected prestressed concrete structures was presented using a fracture-plastic model. A three-dimensional finite element model was successfully validated with experimental results from real-size prestressed and reinforced members affected by ASR.
In summary, this research program addressed the impact of ASR on prestressed concrete beams, shedding light on their residual load capacity. It also introduced AI models for predicting concrete damage and proposed a constitutive model to explain the influence of various factors on ASR expansion. The nonlinear analysis provided valuable insights into the behavior of ASR-affected structures, contributing to the understanding and management of this prevalent concrete degradation issue.
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