M. Naser

Thermal-Stress Finite Element Analysis of CFRP Strengthened Concrete Beam Exposed to Top Surface Fire Loading

A detailed 3D time domain transient thermal-stress finite element analysis is performed to study the heat transfer mechanism within a CFRP strengthened reinforced concrete beam for fire conditions initiating at the top of the beam. This loading scenario has not been investigated previously either experimentally or analytically. Accordingly, a reinforced concrete T-beam strengthened with CFRP and fire-tested by other investigators is modeled here to compare the fire rating of top and bottom exposure. The finite element results correlated very well with the experimental measured results for the bottom fire exposure. In addition, the investigation of the top fire exposure yielded important findings on the resistance of concrete beams when subjected to such fire conditions. It is concluded that heating the top surface (slab) of reinforced concrete beams seems to be beneficial in minimizing mid-span deflection.

Performance of RC T-Beams Externally Strengthened with CFRP Laminates under Elevated Temperatures

This paper presents a numerical study that investigates the performance of reinforced concrete (RC) T-beams externally strengthened with carbon fibre reinforced polymer (CFRP) plates when subjected to fire loading. A finite element (FE) model is developed and a coupled thermal-stress analysis was performed on a RC beam externally strengthened with a CFRP plate tested by other investigators. The spread of temperature at the CFRP-concrete interface and reinforcing steel, as well as the mid-span deflection response is compared to the measured experimental data. Overall, good agreement between the measured and predicted data is observed. The validated model was then used in an extensive parametric study to further investigate the effect of several parameters on the performance of CFRP externally strengthened RC beams under elevated temperatures. The variables of the parametric study include applying different fire curves and scenarios, different applied live load combinations as well as the effect of using di...

Finite Element Modeling of Punching Shear in Two-Way Slabs Reinforced with High-Strength Steel

This paper presents the development of a 3D nonlinear finite element (FE) model to predict the punching shear of two-way reinforced concrete (RC) slabs. Six slabs casted with regular and steel fiber reinforced concrete (SFRC) and reinforced with normal and high strength steel reinforcement were modeled using ANSYS. The results were validated with published experimental data. The computational model accounts for the different nonlinear constitutive material laws by utilizing state-of-the art modeling methodologies. Concrete cracking and softening, effects of the embedded steel fibers, steel yielding, and the bond-slip mechanism of the embedded steel reinforcement were all taken into account. A good correlation was obtained between the predicted and measured results at all stages of loading including failure of the specimens. It is concluded that correlating models could be used as a reliable tool to conduct parametric studies to evaluate the punching shear behavior of twoway slabs cast with normal and SFRC concrete, reinforced with ordinary and highstrength steel reinforcement.