Assessment of structural performance, materials efficiency, and environmental impact of multi-story hybrid timber structures in high seismic zone

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Advancements in wooden manufacture and the inherent sustainable merits of timber have stimulated studies on high-rise wooden structures and their structural performances. Considering the height restrictions of timber structures in Taiwan, two types of hybrid structure systems, reinforced concrete (RC) structure mixed with timber components, were proposed as substitution solutions to explore their feasibility and environmental impact in high seismic zones. A fifteen-story RC structure was adopted as the benchmark building, and building weight, material substitution efficiency, and embodied carbon were thus compared with the proposed hybrid timber structures after determining wind and seismic impacts. The results showed that structure system Type 1, which replaced original RC slabs and RC walls with timber, weighs only 61.3 % of the RC structure, reducing seismic forces by 38.7 % and base shear by 30.6 %, while inter-story drift ratio was smaller than that of RC structure; meanwhile, Type 2, which maintained the original RC service core and replaced timber structure for rest of the area, was only 44.5 % of the structural weight of RC structure, with a reduction of 36.4 % in seismic forces and 21.1 % in base shear. Furthermore, Type 1 featured reduced embodied carbon of 34.8 % and 35.4 % respectively using imported and domestically produced timber, while Type 2 features reductions of 47.4 % and 49.3 % respectively. The study indicated that the RC-timber hybrid structure system not only has significant structural performance in the face of the challenges of high seismic zones but also offers new solutions in terms of environmental sustainability.