Amr Shaat

MODELING OF AXIALLY LOADED HSS SLENDER STEEL MEMBERS RETROFITTED WITH COMPOSITES

This paper describes an analytical model developed to predict the behaviour of axially loaded slender members composed of steel hollow structural sections (HSS), retrofitted with carbon-fibre reinforced polymer (CFRP) composite sheets. A previous experimental study by the authors showed that gain in strength due to CFRP retrofitting was highly sensitive to the specimens imperfection. As such, developing an analytical model was necessary to uncouple the effects of imperfection and number of CFRP layers. The model predicts the load versus axial and lateral displacements, and accounts for initial imperfection, and the contribution of CFRP sheets. The model was verified against results of the experimental program and showed reasonable agreement. The model was then used in a steel plasticity, the built-in through-thickness residual stresses, geometric non-linearity, including increased both the axial strength and stiffness substantially. parametric study. The study demonstrated that retrofitting slender HSS columns using CFRP sheets CFRP layers, it is believed that geometric imperfections have also varied among the specimens. As such, no specific correlation could be established between the amount of strength gain and the amount of CFRP.

Out-of-Plane Bending of Masonry Walls with Near-surface Mounted and Externally Bonded Reinforcement

Summary This paper presents an experimental investigation into the flexural behaviour of masonry walls that have been reinforced using near-surface mounted (NSM) or externally bonded (EB) reinforcement, under out-of-plane loading. The study simulates retrofitting applications and also proposes the NSM technique for new wall construction, using pre-grooved blocks, in lieu of the conventional method of internal reinforcing and grouting. To accommodate the NSM reinforcement, the grooves in the masonry blocks were aligned with ducts used to anchor the NSM reinforcement in the concrete footing. Seven wall specimens were tested, including walls reinforced with conventional and stainless steel bars, glass fibre-reinforced polymer (GFRP), and carbon FRP (CFRP) reinforcement. The study demonstrated the feasibility and effectiveness of the NSM technique for new construction. Walls with NSM reinforcement showed a superior performance to those with EB reinforcement. It was shown that increasing the FRP reinforcement ratio may result in a change of failure mode, and as such, the increase in strength may not be proportional to the increase in reinforcement ratio. NSM steel reinforced walls showed a superior performance in terms of strength, stiffness and the ductility associated with the formation of a plastic hinge at the base.