Integrated optimization of rebar detailing design and installation planning for waste reduction and productivity improvement

Abstract Cutting rebar stocks to fit to specific requirements of designed structural components on a construction project results in cutting losses, which is the major contributor to the generation of construction waste. Previous research developed mathematical models to analytically minimize rebar cutting losses, but without integrating engineering design, workface plan, detailed estimating, plus environmental factors in optimization. In this research, integer programming technique is applied at the first stage to generate the optimal rebar stock procurement plan and cutting plan for each rebar layout arrangement alternative in a particular structural component. Next, pareto optimization techniques are applied to simultaneously optimize total cost and material waste, resulting in the optimal trade-off solution. A reinforcing concrete slab-on-grade case from a classic textbook of detailed estimating is adapted as a test-bed to show that the proposed methodology is capable of producing trade-off solutions in terms of reducing wastage and lowering total cost, leading to identification of the optimal slab rebar layout arrangement plan and generation of associated rebar stock procurement plan, cutting plan and crew installation plan ready for field implementation. “What if” scenario analyses are also provided to further validate the proposed methodology and gain insight in the relationships between input parameters and optimum solutions.