Numerical modeling of time effects on the behavior of two-way reinforced concrete slabs strengthened by FRP sheets.

Nonlinear viscoelastic modeling has been adopted with numerical simulations to investigate the behavior of long-term deflection (creep) of the strengthening two-way slab by FRP sheets under sustained load. Creep is always related to damage, and its one complex phenomenon that is set up differently in each program, so computations are done using the Finite Element Method (FEM) by using the ANSYS/ APDL Ver19.2 program. In the ANSYS program, creep analysis can be done in a variety of ways. One of these is the Prony series' definition of creep function. Which shows the time and creep properties, this paper investigate into it? For that first, the results of creep tests were available in the literature are used to validate the numerical shear modulus calculation of FEM program ANSYS. Which are used for the modeled slabs. In modeling of a slab different types of FE were used. Finally, the results were presented in figures. This study included two parts: the first part included compare the result between numerical and experimental and achieved a good agreement. In the second part included the investigations some important parameters' effect on the behavior of strengthening two-way slab consisted; the sustained load magnitude, compressive strength, length to thickness of the slab, and FRP sheet type. Where analyzed seventy-two models and noticed that: Increasing the sustained load 100% and 200% leads to an increase in deflection about (2 and 2.5) times. An increase (l/h) by 150% leads to an increase mid slab deflection about (5.615) times. Increased the compressive strength of concrete by 50% and 100% led to a decrease in deflection by 12.56% and 17.9%%, respectively. The models strengthening with CFRP have a higher deflection than the models strengthening with GFRP by 14.23% because the GFRP have a greater elastic modulus than the CFRP that is used in this study. [ABSTRACT FROM AUTHOR]