Cold-formed shear walls with burring holes for the seismic strengthening of existing reinforced concrete buildings

Decarbonization is a key priority in the global effort to promote sustainable development and mitigate climate change. A significant contribution can be made by renovating the existing European building stock, which is largely characterized by low energy efficiency and inadequate structural performance. To address this challenge, integrated and sustainable renovation strategies based on Life Cycle Thinking principles have been proposed, aiming to enhance both structural safety and energy performance. In this paper, cold-formed steel panels with burring holes are proposed as earthquake-resistant elements for the integrated renovation of existing reinforced concrete (RC) buildings. These shear walls are used in Japan as lateral force-resistant systems for new lightweight buildings. The proposed retrofit solution offers key advantages, including lightness, ease of installation, and the possibility of disassembly and component reuse, thereby enhancing overall sustainability. Three finite element modelling strategies with varying levels of complexity are presented to capture the behaviour observed in previous experimental campaigns. A design methodology for a retrofit solution for RC buildings is developed, incorporating the stringer-panel model to derive forces in individual elements. Finally, both the modelling approach and design method are validated through application to a reference case study building representative of existing RC structures not designed according to earthquake-resistant provisions. Vulnerability analyses have been performed, demonstrating the effectiveness of the designed retrofit solution involving perforated metal panels.