Huda Saeed

Modeling of Reinforced Concrete Slabs Strengthened with Fiber-Reinforced Polymer or Steel Plates

This study presents finite element models for strengthened two-way slab-column connections. Two different strengthening techniques are modeled using steel plates or fiber-reinforced polymer (FRP) strips or laminates. The connections are categorized according to the strengthening type as flexural or punching shear specimens. FRP-strengthened connections are subjected to central axial loads. The connections that use an assembly of steel plates and bolts are subjected to a central load or a combination of central load and moment. The three-dimensional assembly of the slab and column of the connections is simulated. The interfacial behavior between the FRP materials and concrete is taken into account. A user-defined subroutine for the microplane model for concrete is incorporated in the finite element package. Results are presented in terms of the ultimate load capacities, load-slip relationships, load-interfacial stress relationships, and stress distributions in the strengthening materials. The models presented in this paper showed good agreement with experimental results.

Numerical Modeling of Shear Strengthened Reinforced Concrete Beams Using Different Systems

This research aims at creating finite-element models for fiber-reinforced polymer (FRP) shear strengthened concrete beams. It is inspired by the fact that the determination of the structural behavior of shear strengthened beams requires advanced numerical methods of which results are substantiated by credible experimental findings. The models are developed here to assess the shear and interfacial types of behavior of beams strengthened using one of three different schemes, namely, externally bonded (EB), mechanically fastened (MF), and hybrid EB/MF FRP schemes. The interfacial behavior between the EB, MF, and hybrid EB/MF FRP and the concrete is accounted for using interface elements for both vertical and inclined FRP strips. A user-defined subroutine for the microplane constitutive law for the concrete material is incorporated in the model. Results are presented in terms of the ultimate load-carrying capacities, load-deflection relationships, and interfacial stress/slip distributions. Numerical results are validated against available experimental data and show reasonable agreement. Models for hypothetical cases of MF FRP strengthened beams are created to enrich the discussion on the interfacial bearing stress distributions.