ABSTRACT
This study investigates the idea that “green” buildings should be designed for higher earthquake and other extreme loads to reduce the environmental impacts of post-hazard repairs. To do so, we consider the seismic performance and environmental impact of reinforced concrete frame buildings with varying strengths, by quantifying CO2 equivalent emissions, or embodied carbon, in the context of seismic design decisions. The results suggest that larger structural members of stronger buildings (above-code designs) lead to higher upfront embodied carbon, whereas manufacturing of smaller structural members for weaker buildings produces less upfront embodied carbon. In terms of post-earthquake impacts, we quantify the expected annual embodied carbon from repair activities (considering contributions from a range of possible future seismic hazard events). The results demonstrate that stronger, above-code buildings have lower expected repair costs and embodied carbon than weaker code-compliant or below-code variations, suggesting that—with respect to annualized impacts—stronger buildings are in fact “greener.” Deaggregating these results reveals that at lower hazard levels (representing more frequent events), stronger buildings experience lower drift and acceleration demands than code-compliant or below-code variants, leading to lower seismic losses and embodied carbon. However, at higher hazard levels, increased stiffness from lower fundamental periods of stronger buildings can increase the influence of nonstructural losses on repair embodied carbon generating somewhat higher emissions. Although certain details differed, the overall trends were consistent between space and perimeter frames.
