Impact of Seismic Design on Embodied Carbon and Construction Cost in Multi-Storey Reinforced Concrete Frame Buildings

Abstract

The building industry is a large contributor to global greenhouse gas emissions. The construction and building materials processes alone account for a large portion. While seismic design is imperative to keeping structures safe in regions that experience earthquakes, it often increases the volume of materials needed for construction, worsening the environmental and economic consequences. As a result, this research seeks to assess the degree to which seismic design impacts the Embodied Carbon (EC) and construction budgets of reinforced concrete structures of differing heights, enabling a more informed carbon-cost analysis for those carbon-conscious structural designs. Buildings of 2-, 4-, 6-, and 8-story height, and both seismic and non-seismic design scenarios, were analysed. All designs appropriately used SNI 2847-2019 and SNI 1726 for seismic provisions. The structural design for slabs, beams, and columns, and detailed structural modelling material constituted the core building blocks for material volume quantification. Construction cost was derived from the built-up method, and EC was derived from the legal provisions for concrete and steel. The total EC, cost, and their distribution by elements were used to derive prioritization to assist the cost optimization. The outcome illustrates the volumetric consequences of seismic design and how it diverges as height increases. In the case of the 8-storey building, the seismic design has 54% more Embodied Carbon (EC) and 79% more increased cost in comparison to the non-seismic design. For non-seismic buildings of all heights, slabs more than 50% of the time controlled the EC and cost. However, for the seismic buildings, the dominance of the slabs reduced as they got taller, and the columns started to take more due to the increased seismic detailing provisions. The carbon-cost trade-off analysis indicated a strong linkage between cost and EC, and the non-seismic mid-rise buildings provided the most balanced performance. This shows that the EC assessment in regions with a high seismic risk should be considered as a design criterion to mitigate the impact of economically and environmentally seismic detailing provisions in the code. Improvements in cost and sustainability can be achieved by controlling slabs in non-seismic designs and improving columns in seismic designs.