Behaviour of lightweight concrete beams strengthened with carbon fibre reinforced polymer in shear

Al-Allaf, MHF

Abstract

Epoxy bonded fibre reinforced polymer (FRP) composites are widely used for the retrofit of ailing reinforced concrete structures, for both shear and flexure. This technology provides unique features compared with conventional retrofitting systems. Among these FRP has good corrosion resistance, lightweight and excellent mechanical properties. Furthermore, the manual lay-up system allows using the FRP reinforcements to any member’s shape.

A significant amount of research has been carried out to understand the shear behaviour of normal weight concrete (NWC) members strengthened with FRP composite. Increasing interfacial (shear) and normal stresses with increasing plastic deformation lead to FRP debonding and/or FRP rupture failures. The response of strengthened concrete members subject to load is governed by the bond strength and the material characteristics of the epoxy bonded FRP reinforcement and the concrete. However, lightweight concrete (LWC) beams, which use Pulverised Fuel Ash (Lytag) instead of normal aggregates, retrofitted to increase shear capacity with epoxy bonded FRP have not been studied comprehensively to understand the characteristics of FRP/ lightweight concrete joining and the shear resisting mechanism.

This study comprises of experimental, numerical and analytical investigations of the interface behaviour between carbon fibre reinforced polymer (CFRP) reinforcement and lightweight and normal weight concrete. In addition, the shear behaviour and failure modes of LWAC and NWAC beams is studied. The influence of various variables on the response of the CFRP/lightweight concrete joint and the shear response of reinforced concrete beams are examined by testing large numbers of the experimental series.


Three-dimensional non-linear finite element and mathematical models are employed to study the response of the CFRP-to-lightweight concrete interface and the FRP contribution to the shear resistance of lightweight concrete beams have been proposed in this study. Proposed finite element models and relationships were compared with experimental results. The results of the finite element and analytical models demonstrated the capability of these models in predicting the interface behaviour of lightweight concrete/FRP joints and the shear strength gained due to CFRP reinforcement used to retrofit lightweight concrete beams in shear.

Citation

Al-Allaf, M. Behaviour of lightweight concrete beams strengthened with carbon fibre reinforced polymer in shear. (Thesis). University of Salford

• Thesis Type: Thesis
• Deposit Date: Jan 15, 2018
• Publicly Available Date: Jan 15, 2018
• Award Date: May 23, 2017