CO2 mitigation strategy in Brazilian concrete slabs: a reliability-based approach at negative cost

Resumo

In recent years, extreme climate events such as floods, wildfires, heatwaves, and prolonged droughts have been observed with increasing frequency, intensity, and geographical spread. Due to this, there has been growing interest in sustainability, particularly in structures, since the construction and operation of buildings account for approximately 37% of global CO₂ emissions. Thus, dematerialization is an extremely relevant topic for the conscious and rational use of natural resources in buildings. However, current Brazilian technical standards do not reflect this concern, being potentially conservative without significant gains in structural safety. To align these two interests, reliability theory can be applied, ensuring structural safety while reducing the environmental impact of constructions. The initial goal of the reliability-based calibration of partial safety factors was to achieve more uniform safety levels across different structural designs. As an additional benefit, it was possible to observe a reduction in design loads and, consequently, in construction material consumption. In this study, CO₂ emission reductions in slabs were evaluated by comparing a design using standard safety factors from design codes and using reliability-based calibrated factors. The Brazilian tool Sidac was employed to estimate CO₂ emissions. Using the calibrated partial factors, an average 7.65% reduction in CO₂ emissions and a 7.41% cost reduction were achieved in the design of case-study slabs.