Life cycle assessment of seismic retrofit alternatives for reinforced concrete frame buildings

Reinforced concrete structures designed prior to modern building codes are still in use today. These structures are known for their inadequate design and fragile performance during earthquakes. Over the past decades, several seismic retrofitting alternatives have been proposed as strengthening solutions for these buildings. Since the construction industry has a significant environmental burden, the impacts of the retrofit solutions should also be considered in the decision-making process of a possible seismic strengthening intervention. In this study, we performed a life cycle assessment (LCA) analysis of three seismic retrofit alternatives for reinforced concrete structures, namely, RC column jacketing, beam weakening, and shear walls. An 8-story reinforced concrete case-study building available in the literature was adopted for the LCA analysis. The environmental impacts of the selected alternatives were quantified from cradle-to-grave and two disposal phase options were studied in a sensitivity analysis: landfilling and recycling. Detailed calculations and assumptions were made in order to obtain the inventory data for the impact assessment of the three alternatives. The calculated LCA results were compared and interpreted among the analyzed retrofit alternatives. The shear wall total environmental impacts were the highest of all the studied alternatives. The pre-installation (i.e., production) and disposal of the materials required by each alternative were the phases with the highest environmental impacts, while transportation impacts were comparatively small. Recycling of the construction and demolition waste reduced the environmental impacts in the disposal phase by 29%-53%, with a lower total environmental impact reduction of 12%-42% for all the retrofit alternatives studied.