Optimum design of wind turbine foundation according to rebar detailing

Abstract

This research proposes a Mixed Integer Linear Programming model to assist structural engineers in the reinforcement detailing phase of circular foundations, with a specific focus on wind tower foundations, aiming to optimise the design process and, consequently, reduce the costs associated with constructing these elements. After analysing the internal forces in circular foundations, the designer must define the calculation sections to determine the required area of steel and select the diameter of the steel bars and their positioning in the base. This determination is often based on the designer's experience, which can lead to choices that unnecessarily increase costs, thus justifying the creation of a model to optimise this process. The proposed model consists of three phases: the first involves a non-linear regression to obtain an equation that represents the bending moments at any point in the foundation; the second applies a linear quadratic model to choose the ideal layout of the calculation sections; and the third uses a binary integer linear model to determine the ideal diameter of the bars and their consequent positioning. This search for optimality must comply with the restrictions imposed by normative criteria, including maximum bar lengths and rebar lap splices, maintaining good constructability based on standardisation. Validation tests were conducted with confirmed cases using the proposed model, resulting in an average reduction of 10.72 % in the value of the rebar weight due to the model's second stage and a decrease of 12.28 % in the best case during the final step. It can, therefore, be concluded that the proposed model is viable for application in circular foundation projects, leading to savings in the total weight of steel used in the foundations.

Keywords

• Wind Turbine Foundation
• Circumferential Reinforcement
• Mixed-Integer Linear Programming