Non-linear finite element analysis of prestressed T-beams strengthened with FRP laminates and patch anchors

Although fiber reinforced polymers (FRPs) have become the most widely used material to strengthened existing concrete structures in shear, premature debonding of externally bonded FRP remains a significant cause of material under-utilisation. In an effort to suppress debonding failure, research has shown that the use of +/- 45 degrees bidirectional fabric patch anchors can delay the occurrence of FRP debonding. However, most research to date on patch anchors has been based on joint-level tests and the data available on full-scale beam applications has been very limited. One means by which additional data can be generated on the performance of patch anchors when applied to full-scale beams is using finite element simulations. This paper presents a 2D and 3D non-linear finite element model calibrated using available data on prestressed T-beams strengthened in shear with FRP laminates and patch anchors. The models captured the failure modes, strains in the FRP and crack patterns of the specimens very well and predicted the failure load for the control, strengthened and anchored specimens within a margin of difference of 6-9%, 4-13% and 1-2%, respectively. Parametric studies involving variation of concrete strength and FRP thickness were conducted to generate additional data and the research findings are presented.

Automated summary

This paper presents a finite element simulation study on the effect of patch anchors on the performance of full-scale beams, with a calibrated model accurately predicting the failure load. The research findings indicate that patch anchors can effectively delay the debonding of FRP and improve material utilization.