Layout optimization of post-tensioned cables in concrete slabs

This paper presents a new method for optimizing the layout of post-tensioned cables in concrete slabs. The cables are modeled using three-dimensional B-splines so that the prestressing forces are derived according to the exact geometry and subsequently projected onto the finite element mesh of the concrete slab. The control points of the splines serve as shape design variables, allowing non-trivial 3D cable layouts to emerge and thus extend the design capabilities beyond traditional concepts. Results of several realistic design examples show that significant reduction in cable weight is possible while maintaining the required structural performance. Savings in the order of 20% in cable weight are demonstrated for simple and regular floor plans. For irregular plans, the savings can exceed 50%, when compared to contemporary practical design approaches.