Seismic Performance Evaluation Of FRP Retrofitting Concrete Structures Based On Capacity Spectrum Method

The pushover analysis method is a good means to evaluate the earthquake-resistance of building structures, which has been widely used in the reassessment of lateral force resistant system of as-built structures or newly-designed structures. This simple and effective method does not contain the complex solution process as included in commonly-used nonlinear dynamic analysis method. The application of fiber reinforced polymer (FRP) to the seismic retrofit of concrete structures can lead to more efficient construction process and easier quality control. Unfortunately, the technologies of retrofitting with FRP are now focusing on capabilities of the elements but the structures. The technologies of retrofitting with FRP could find the weakness of the original structure and particular enhancement of the retrofitted structure if it was used with the pushover analysis method.Here, the researches are mostly on the particular process of the technologies retrofitting with FRP used with pushover analysis method besides the discussion of the capability of the retrofitted structures.One side, the strength reduction factor models are compared which is the core of the Capacity spectrum method with the average strength reduction factor spectrum got through the statistical analysis of 60 earthquakes, the result shows that Fajfar model is mostly the best in all kinds of sites.On the other side, 3 retrofit methods based on experiments and theories are been compared, they are direct retrofit method, equivalent hoop method and the analysis of the section of the element retrofitted with FRP. At last, the result shows that the analysis of the section of the element retrofitting with FRP can compute the most important character points like elastic point, yield point and ultimate point, besides, it gives us the best result, it is the ideal method to research the capability of the elements retrofitted with FRP today.At last, the particular compute progress of the technologies retrofitted with FRP used with pushover analysis method is showed through a 6 stories structure which elements is defined by the analysis of the section. After the compare of the capabilities of the original structure and the retrofitted structure, the result shows that the structure's ductility after retrofitted effetely enhanced and the capacity of resisting earthquakes is much better. The technologies retrofitting with FRP used with capacity pectrum method can show the weakness of the origin structure and the enhancement of retrofitted structure clearly, is an ideal design method using FRP.