Japanese State of the Art on Seismic Retrofit by Fiber Wrapping for Building Structures: Evaluations

Using the database consisting of 236 R/C column specimens conducted in Japan, the characteristic behaviors of strengthening by fiber wrapping were analyzed. The following findings were obtained: (1) The amount of shear reinforcement, the span to depth ratio, the axial compressive stress level influence on the strength and deformation capacities of retrofitted columns by fiber sheet wrapping (2) Shear strength of retrofitted columns can be predicted by previous design equations based on the strut and tie models as same as for usual R/C columns, in which the effective fiber strains of about 1% is appropriate. (3) There are few test data about the confining effect of fiber sheet wrapping on bond resistance of longitudinal bars. Further research effort is required to evaluate the shear strength of columns governed by the splitting of cover concrete along longitudinal bars. (4) The ductility ratio can be roughly estimated as a function of the shear to flexural stress ratio. (5) For the specimens with plain round longitudinal bars, the previous equations based on the strut and tie model cannot be applied because of the poor bond capacity.