Optimization of Rebar Usage and Sustainability Based on Special-Length Priority: A Case Study of Mechanical Couplers in Diaphragm Walls

The construction industry generates significant CO 2 emissions and reinforcing bars (rebar), which are a major contributor to this environmental impact. Extensive research has been conducted to address this particular issue. Recent research advances have introduced algorithms to reduce rebar waste and consumption, demonstrating the feasibility of achieving near-zero rebar cutting waste (N0RCW) through the consideration of special-length rebars. However, conventional lap splices, the most common rebar joint method, continue to consistently consume excessive quantities of rebar, despite extending beyond their mandated zones. Conversely, couplers can eliminate rebar lengths required for lapping splices, reducing the usage of rebar. Applying special-length rebars and couplers in heavily loaded structures like diaphragm walls can also significantly reduce rebar usage and cutting waste, consequently reducing CO 2 emissions and the environmental and economic impacts. This research aims to optimize rebar consumption and sustainability in diaphragm wall structures by integrating mechanical couplers with a special-length rebar approach. A case study confirmed a substantial reduction in purchased rebar usage (17.95% and 5.38%), carbon emissions (15.24% and 2.25%), water footprint (17.95% and 5.38%), and environmental impact (95.18% and 30.27%) compared to the original design and recent diaphragm wall study, respectively. The broad implementation of the proposed method across various buildings and infrastructure projects could further multiply these benefits, enabling the achievement of the sustainable development goals (SDGs) adopted by the United Nations to foster sustainable construction.