Elsevier

Computers & Structures

Volume 240, November 2020, 106335
Computers & Structures

Graphic statics in a continuum: Strut-and-tie models for reinforced concrete

https://doi.org/10.1016/j.compstruc.2020.106335Get rights and content
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Highlights

  • Bridging the gap between layout optimization and graphic statics.

  • A new algorithm for algebraic graphic statics to optimize indeterminate structures.

  • Allowing direct interactive manipulations of strut-and-tie models and their forces.

  • Overcoming the drawback of conventional optimization in providing a single solution.

  • Overcoming the drawback of graphic statics in requiring an initial diagram.

Abstract

This research bridges the gap between the numerical layout optimization method and the geometry-based analysis and design method of graphic statics. The study connects the two methods for the application of strut-and-tie models in reinforced concrete design. It suggests a new algorithm for the algebraic graphic statics of indeterminate trusses inspired by the layout optimization method. This research also contributes to the field of graphic statics by providing a formulation that generates form and force diagrams in a continuum, where the topology for none of the diagrams is initially provided.

The generation of strut-and-tie models for reinforced concrete has extensively relied on optimization methods, which are helpful techniques for the initiation of a load path inside a continuous domain. However, the resulting truss model is a single answer, and there exists limited control to methodically modify the topology or the force distribution of the model. Furthermore, the minimized-weight truss does not guarantee a practical strut-and-tie model or an optimized performance of a reinforcement design.

In contrast to the conventional optimization techniques with a single solution, the intuitive method of graphic statics provides the designer with a vast design space. It also offers explicit control over the geometry and force distribution of the generated truss models. The algorithm provided in this paper is applied to various continuous domains to systematically generate a variety of strut-and-tie models, their force diagrams, and constant stress fields. The production of the optimized truss model and its force distribution allows the direct interactive manipulations of the design while observing the changes in the stress fields and the reinforcement arrangement. The open-source repository of the implemented integrated algorithm and the examples used in this paper are also provided.

Keywords

Strut-and-tie model
Graphic statics
Layout optimization
Load path optimization
Reinforced concrete

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