Nonlinear Finite Element Analysis Of RC Structures Strengthened With CFRP Composites

As a new structural engineering material, carbon fiber-reinforced plastic(CFRP) has many advantages of excellent mechanical strength and deformation property, convenience in use, low weight, non-dimensional increase, and immunity to corrosion. In recent years, there has been extensive research on the use of CFRP sheets to replace steel plates in strengthening deficient reinforced concrete (R.C.) structures. The price of these materials in civil engineering applications have been coming down rapidly, enabling their wider applications in civil engineering. The finite element method (FEM) can simulate the behavior of beams from linear through nonlinear responses and up to failure. Finite element analysis can also be used to model the behavior numerically to confirm calculations, as well as to provide a valuable supplement to the laboratory investigations, particularly in parametric studies.In this paper, the stress-strain relationships of concrete confined by CFRP are introduced, and the flexural and shear behavior of RC structures strengthened with externally bonded CFRP sheets are discussed together. At the same time, finite element method models are developed to simulate the behavior of R.C. structures strengthened with externally bonded CFRP sheets.Comparisons are made for load-strain plots at selected locations on the beams; load-deflection plots at midspan; first cracking loads; loads at failure; and crack patterns at failure. Modeling simplifications and assumptions developed during this analysis are presented. The study compared strains from the FEM analysis with measured strains from load tests. Conclusions from the current research efforts and recommendations for future studies are included.Analysis of R.C. frame strengthened with CFRP subjected to minute earthquake and disastrous earthquake with FEM are presented. After modal analysis, the natural frequencies and mode shapes of R.C. frame are obtained. Then the dynamical responses of R.C. frame are studied with transient analysis. The study compared responses of R.C. frame with that of R.C. frame strengthened with CFRP. The results indicate that strengthening R.C. frame with CFRP can effectively reduce the seismic responses.