Alternative Performance-Based Retrofit Strategies and Solutions for Existing RC Buildings: Fid-Bau Portal

Alternative Performance-Based Retrofit Strategies and Solutions for Existing RC Buildings

Pampanin, Stefano

The need for simple and cost-effective retrofit solutions for existing reinforced concrete buildings, particularly those designed before the 1970s, thus prior to the introduction of modern seismic code provisions and capacity design principles, is no longer “just” an academic or scientific research statement, but it is eventually being recognized as a critical socio-political priority at international level. Similarly to what pursued for the design of new structures, a performance-based approach should be adopted when assessing the vulnerability and defining the retrofit strategy for existing buildings. In this latter case, the target limit states or performance levels have to be more realistically adjusted to account for the difficulties encountered in the assessment phase, as well as for the several issues associated to costs, feasibility and invasiveness of the proposed strengthening/retrofit solution. In this contribution, the concept of a partial retrofit strategy, capable of achieving an intermediate but critical objective as the collapse prevention, and based on practical solutions able to be almost “standardized”, is proposed as a more realistic whilst effective upgrading strategy, particularly when planning a wide intervention at territorial scale. An overview of alternative retrofit strategies and technical solutions developed and/or further refined in the past few years as part of a multi-year research project on-going at the University of Canterbury on the seismic retrofit of existing reinforced concrete buildings is given. The feasibility and efficiency, in the contest of a performance-based retrofit approach, of adopting and/or combining different solutions such as Fiber Reinforced Polymers, low-invasive low-cost metallic diagonal haunches, post-tensioning wall systems or selective weakening techniques, is also discussed, based on numerical and experimental evidences.