Nonlinear Analysis of Reinforced Concrete Beams Strengthened with Prestressed CFRP sheets Under Cyclic Load

Abstract

Analysis of reinforced concrete beams strengthened by prestressed CFRP sheets has been investigated in this paper. A three dimensional finite element analysis ANSYS computer program (version 9.0) was conducted to obtain the response of the strengthened beams. The eight –node brick elements(solid 65) are used for the idealization of concrete while the CFRP sheets are idealized by using three-dimensional layered elements (solid 46).The steel plates are idealized by using three dimensional solid elements (solid 45).Five beams are analyzed in study ,four with prestressed –CFRP sheets and one with non-prestressed- CFRP sheet. The effect of different level of prestress ,induced by prestressing the CFRP –sheets, on the cracking loads and  flexural stiffness of the strengthened beams are studied. It is found that the cracking load and the flexural stiffness are significantly increased as the level of prestress increased. The response of the strengthened beam under cyclic loads is also conducted in terms of deflection versus number of cycles which is related to the cyclic behaviour of the constituent materials used in the beam ( concrete , tension steel, and CFRP sheets).

The deformation of each these materials under cyclic loadings is presented in terms of measured strains as a percent of the number of cycles of fatigue. The results obtained from finite element analysis are compared with available   experimental results and the comparison gives good accuracy