Buckling Analysis of Steel Plates Reinforced with GFRP

• Main Author: Zaghian, Sepideh
• Other Authors: Mohareb, Magdi
• Language: en
• Published: Université d'Ottawa / University of Ottawa 2015
• Online Access: http://hdl.handle.net/10393/32788; http://dx.doi.org/10.20381/ruor-4172

Glass Fiber Reinforced Polymers (GFRP) plates have recently received attention as a viable option for reinforcing existing steel members. Possible application involve web strengthening of existing plate girders and reinforcing corroded flanges and/or webs where a steel plate under combination of shear and/or normal stresses can be governed by their buckling strength. Using GFRP as a retrofit material is attractive from several respects such as easy application, achieving high additional strength with low additional weight, and corrosion resistance. Since the elastic properties of the GFRP, adhesive, and steel are orders of magnitudes apart, reliable predictions of the buckling strength of such systems necessitates careful 3D modelling involving significant modelling and computational effort. Within this context, the present study develops a simplified buckling theory for steel plates symmetrically reinforced with GFRP plates and subjected to in-plane biaxial normal stresses and shear. The theory idealizes the steel and GFRP as Kirchoff plates while accounting for the transverse shear deformations within the adhesive layers. A variational formulation is first developed based on the principle of stationary potential energy. The validity of the variational formulation is then assessed through systematic comparisons with results based 3D finite element models for a variety of buckling problems. The variational principle thus validated, is then used to develop a finite element formulation. The new element features four nodes with five degrees of freedom per node. Results based on the finite element are compared to results based on 3D modelling to assess its validity. The element is then used to investigate the effect of GFRP thickness, adhesive thickness, and adhesive shear modulus on the critical pressure of composite systems for practical retrofitting problems. It is shown that GFRP thickness is particularly effective in increasing the capacity of the composite system, while the effect of the adhesive layer shear modulus low to moderate. Conversely, an increase in the adhesive thickness is found to correspond to a decrease in buckling capacity of the composite system.