Assessment on carbon footprint of steel frames for building structures
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Insinööritieteiden korkeakoulu |
Master's thesis
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Authors
Date
2020-12-14
Department
Major/Subject
Mcode
Degree programme
Master's Programme in Building Technology (CIV)
Language
en
Pages
78+22
Series
Abstract
Life Cycle assessment method is currently used to assess the carbon emissions coming from buildings. The Finnish Ministry of the Environment aims to include the carbon assessment as a part of building’s preliminary design. However, these new assessment guides exclude the contributions from connection components in the load-carrying frames. Moreover, with the improvement of operational energy efficiency, the impact of embodied carbon emissions has relatively been creased, thus lead to encourage the use of timber over steel for building structures. Although more studies have focused on the emissions of structural materials, few studies have attempted to evaluate the combined effects of different static models on carbon emissions. Especially buildings with large open spaces are often built with frames consisting of columns and beams. This study aimed to determine the contribution of the frame types to the total carbon footprint of the steel-framed building structures. The thesis focused on three types of building frames: a pinned, rigid, and semi-rigid frame. The goal was to determine the options available to a designer when prioritizing the lowering of emissions for the whole structure. The frames were modelled from steel members with typical configurations, such as truss structures in long spans and single beams in shorter spans. Additionally, a wooden frame was modelled for a reference point of total carbon emissions for the steel frames. Results show that frame types contribute more to the carbon emissions of a structure and therefore were relevant part in lowering of carbon emissions. In the models used in this thesis, frames with mast columns and pinned beam connections performed better than the other frame types. Whereas the studied semi-rigid frames had the highest carbon emissions compared to the other two frame types. Moreover, in comparison of member types, frames made of open profiles performed better than the ones made of tube profiles of higher steel strength. The studied steel frames had 2.66 times higher emissions on average compared to the studied wooden frames, when the operating time of the structures was set to 100 years. In addition, connections are proved to be responsible for 13-33 % of carbon emissions of the studied frames.Description
Supervisor
Lu, WeiThesis advisor
Inkala, FiaMajoinen, Laura
Keywords
carbon footprint, LCA, EPD, GWP, steel structure, steel frame