A novel hybrid composites wrapped rebar is developed to overcome the brittleness of fiber reinforced polymer( FRP) rebars.Theoretical and experimental studies are carried out on two types of rebars wrapped by FRP and hybrid composites,respectively. The stress-strain curves under quasi-static loads are given. The results show that FRP or hybrid composites outside rebars improve the ultimate tensile stress and the rebar in the core improves the ductility. It is also observed that hybrid composites wrapped layer can provide higher compatibility and lower interlaminar shear stress than FRP wrapped layer.
The eigenvalue problem about a nonhomogeneous semi-infinite strip is investigated using the methodology proposed by Papkovich and Fadle for homogeneous plane problems. Two types of nonhomogeneity are considered:(i) the elastic modulus varying with the thickness coordinate x exponentially,(ii) it varying with the length coordinate y exponentially. The eigenvalues for the two cases are obtained numerically in plane strain and plane stress states, respectively. By considering the smallest positive eigenvalue, the Saint-Venant Decay rates are estimated, which indicates material nonhomogeneity has a significant influence on the Saint-Venant end effect.
