FRP Seismic Retrofit Strategy
Principal Researcher: Stefano Pampanin
Staff involved: Athol Carr
Students involved: Umut Akguzel
Investigation on the feasibility and efficiency of a seismic retrofit intervention using externally bonded FRP composites on existing reinforced concrete frame systems, designed prior to the introduction of modern standard seismic design code provisions in the mid-1970, with particular attention to protect the joint shear failure brittle mechanism.
Analytical and experimental investigations on beam-column joint subassemblies and frame systems have been carried out at University of Pavia. The details of the specimen could be right away used as NZ standard practice prototype. A multi-level retrofit strategy, following hierarchy of strength considerations, has been developed to achieve the desired performance.
Umut Akguzel is currently testing a retrofit solution for exterior 2D and 3D beam-column joints typical of pre-1970 design using Glas fibers (GFRP). Satisfactory results have been achieved on the first specimen, we are now moving on with the preparation of the second one and more have to come. The initial part of the theoretical design has been carried out in conjunction with Gabriele Attanasi, exchange student from Pavia, now enrolled as a Ph.D. at the ROSE school.
A simplified analytical procedure able to predict the enhanced non-linear behaviour of the panel zone region, due to the application of CFRP laminates, in terms of shear strength (principal stresses) vs. shear deformation, has been developed refining and extending available work in literature (fib, Triantafillou) to account for the variation of axial load inhte panel zone and proposed in recent publications. There was (still) is a critical lack of information available on improvement of the joint shear resistance in current FRP guidelines (i.e. fib bulletin or similar).
Simplified hand calculations for flexural strength capacity, using dimensionless formula and alternative combined limit states approach (i.e. different failure domains) , have been developed and need to be completed.
