Relationship between the seismic resistance capacity and the expected total life-cycle environmental impact of an RC building

Abstract

The operational emissions that occur during the use of the buildings and the embodied emissions that occur after the construction of the buildings are substantial. Buildings are responsible for a significant part of the total energy-related carbon emissions. All life cycle stages need to be considered in order to calculate environmental impacts in buildings. Life Cycle Assessment (LCA) is a methodology used to determine the environmental impacts of a product or service over its lifetime and to identify the processes that cause these impacts. Life cycle assessments for a product include all stages from the extraction of the raw material to the disposal or recycling of the product. Many studies have been conducted on embodied and operational emissions in the assessment of the environmental impact of buildings. In addition, it is a very innovative and meaningful approach to consider the seismic damage that the building will receive throughout its life. While evaluating the life cycle results, the calculation of the losses due to the repairs related to seismic damage will also increase the reliability of the results. The expected losses associated with seismic damage can be obtained by integrating the seismic hazard at the site with the fragility curves representing the capacity of the building. As a result, expected life cycle environmental impact can be assessed by considering both the potential seismic damage during the building lifetime as well as the initial impact caused while constructing it. This thesis presents an approach that evaluates the total life cycle environmental impact depending on the ductility class choosen while designing the structure. The behavior factors provided in codes depend on the ductility level. The study reveals relationship between the ductility class considered in the design and the expected total life cycle environmental impact of the building. The purpose of this thesis is to find an answer to making logical choices in terms of environmental impacts while choosing the ductility class. The case study building is a 6 story residential building with reinforced concrete structural walls. The detailing of the case study building was made based on 3 alternative approaches all of which were complying with Turkish Building Earthquake Code (TBEC, 2018) regulations. A different finite-element model was developed for each design approach. One of the models represented the design that corresponds to limited ductility design. The behavior factor R was set equal to 4 and the building was detailed to have a high resistance capacity. Other two models were designed according to the provisions for high ductility. The behavior factor R was set equal to 7 in the design of these two models. The difference among these two models were related to the reinforcement content in the walls. One model was designed to have a higher reinforcement content and strength capacity compared to the other. Basically, considered set of models represented the alternative design strategies that can be utilized by the engineer while designing the same building.