Minimization of Rebar Cutting Waste Using BIM and Cutting Pattern-Oriented Multiobjective Optimization

Rebars are among the main materials used in reinforced concrete structures and among the costliest and most carbon-intensive construction materials. However, during the construction phase, rebar cutting schemes are usually not rationalized enough and may lead to up to 8% waste. Previous studies and practices showed that obtaining data on rebar cutting can be labor intensive and imprecise, lacking the profiling of quantity take-off factors. Additionally, existing optimization techniques often do not adequately consider field characteristics, such as the number of cutting patterns and the scale of the problem, and the characteristics of the cutting data. This study proposes a practical, integrated approach for minimizing rebar cutting waste during the construction phase. The proposed approach consists of two main parts. The first part is obtaining rebar cutting data based on building information modeling (BIM). In this paper, the main influencing factors of rebar quantity take-off are analyzed, and the modeling hierarchy is divided based on these factors to obtain accurate cutting data. The hierarchy also reflects repeatable commonalities between different rebar systems, which helps reduce repetitive modeling efforts and increase efficiency. In the second part, a cutting pattern-oriented multiobjective optimization method is proposed to optimize the cutting scheme. The process is divided into three stages: generating valid cutting patterns, optimizing their frequency, and combining a small number of remaining components. The method combines three algorithms—column generation, particle swarm optimization, and best-fit decreasing—to solve the problem according to the characteristics of each stage. The influence of multiobjectives on the final optimization result is further explored through a sensitivity analysis. The integrated approach was validated with test sets of different sizes, types, and complexities. Its effectiveness and generalizability in reducing rebar cutting waste contribute to its applicability and the achievement of construction sustainability goals.