| 1. |
- Alic, Vedad, et al.
(author)
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Bi-directional algebraic graphic statics
- 2017
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In: Computer-Aided Design. - : Elsevier BV. - 0010-4485. ; 93, s. 26-37
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Journal article (peer-reviewed)abstract
- A pre-existing algebraic graphic statics method is extended to allow for interactive manipulations of the force diagram, from which an updated form diagram is determined. Newton's method is used to solve a set of non-linear equations, and the required Jacobian matrix is derived. Additional geometric constraints on the form diagram are introduced, and methods for improving the robustness of the method are presented. We discuss the implementation of the method as a back-end to an interactive application, and demonstrate the usability of the method in several examples where the qualities of directly manipulating the force diagram are emphasized.
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| 2. |
- Alic, Vedad, et al.
(author)
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Bi-directional Algebraic Graphic Statics : On Force Diagram Constraints
- 2017
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Conference paper (peer-reviewed)abstract
- This paper presents a study exploring the capabilities of a new method, described by Åkesson and Alic [1], which extends the capabilities of the algebraic graphic statics method, by Van Mele and Block [11]. The new method extends the algebraic graphic statics method by making it bi-directional i.e. allowing for determination of an updated form diagram by making direct interactive manipulations of the force diagram. In the new method, Newton’s method is used for solving a set of non-linear equations, to find an updated form diagram from given changes in the force diagram. Additional geometric constraints are introduced on the form diagram to obtain desired solutions. The implementation of the method as a back-end to an interactive application is discussed, and the usability of the method is shown in examples where the qualities of directly manipulating the force diagram are discussed. The main part of this paper will supplement Åkesson and Alic [1] by presenting further studies of the application of constraints to the force diagram, and which shapes this leads to in the form diagram. Further, the paper will present how to adapt force and form diagrams for interactive graphical representations suitable for computers.
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| 3. |
- Alic, Vedad
(author)
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Computational Methods in Conceptual Structural Design
- 2018
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Doctoral thesis (other academic/artistic)abstract
- Conceptual design is the first phase in the design process in which all the requirements and design objectives are synthesized into conceptual alternatives. In practice today, major decisions regarding the buildings function, massing, and overall form are usually made during the first phase. Considering structural performance requirements during conceptual design enhances interdisciplinary interaction, and creates a visual link between form and numeric performance evaluations, reducing work on poorly performing solutions. To include structural performance in conceptual design requires, amongst other things, the availability of tools such as simulation software, suitable for conceptual studies.The aim of the research is to develop new efficient methods and procedures for supporting an interactive and iterative design process that includes engineering aspects. By integrating engineering knowledge and physical aspects in the developed tools, a more efficient and better-adapted design process can be obtained. Supporting an interactive and iterative design process requires new interaction models and numerical approaches in the tools used.The research is limited to three different areas. The first area is related to conceptual studies for reducing ground borne wave propagations in an urban scale. A tool is developed for simulating forms with masses placed on top of soil in an urban scale and studying the resulting effect that the forms have on the propagating waves. The tool uses the finite element method and studies the vibration reduction effects in the frequency domain. Paper A presents the tool and draws some conclusions related to the levels of vibration reduction for various patterns, showing that some patterns are effective in mitigating the incoming vibrations. The approach in the tool makes it possible to obtain results in minutes, allowing the user to generate many alternative proposals quickly, and act as an aid in brainstorming sessions.Papers B and C focus on a recent extension of the finite element method, isogeometric analysis, that is the subject of the second area. The implementation of isogeometric analysis with membrane elements for form finding of efficient shapes for shells is presented. The dynamic relaxation method is used for finding the static solutions. The method is employed directly on design geometry, which is described by non-uniform rational b-splines (NURBS), without the need for any further discretization. Paper B investigates various selections of mass and damping for the dynamic relaxation method with NURBS based membrane elements. The resulting methods are implemented in two plug-ins for the computer aided design applications Rhinoceros 3D and Grasshopper 3D, of which the former is presented in Paper C. The method describes form found geometries well with very few elements and can be used to explore different efficient shapes for shells very rapidly and directly in design software, and is thus suited for design explorations.The third area is about graphic statics -- an old method which is again gaining popularity due to progress in CAD and computational methods. The strength of the method is in an intuitive and graphical representation of form and the internal forces of static equilibrium, which are presented in two diagrams -- the form diagram, and the force diagram. The current research efforts in graphic statics aim to apply the method as a design tool rather than to use it for analysis. A second aim is to investigate the benefits of computer based graphic statics. Paper D presents a root finding approach for computing a form diagram based on manipulations of a force diagram. Paper E presents an algebraic method for computing form diagrams based on force diagrams. Paper F presents an application of graphic statics for automatically generating initial strut-and-tie patterns.
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| 4. |
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| 5. |
- Alic, Vedad, et al.
(author)
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Form finding with dynamic relaxation and isogeometric membrane elements
- 2016
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In: Computer Methods in Applied Mechanics and Engineering. - : Elsevier BV. - 0045-7825. ; 300, s. 734-747
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Journal article (peer-reviewed)abstract
- A method for form finding with dynamic relaxation and Non-Uniform Rational B-Splines (NURBS) based isogeometric membrane elements has been implemented and studied regarding the influence of the discretization and element shape on the form finding. The procedure allows for rapid form finding since NURBS describe the curved geometry well and it is shown that the form-finding can be performed using a coarse mesh. However, to minimize the bending strain energy a fine mesh is needed. Using smaller elements is more advantageous than increasing the degree of the basis functions, keeping the number of integration points few and converging at a lesser number of iterations. Using isogeometric analysis (IGA) simplifies further studies since the form-found shape can be exactly represented with a shell element formulation. The method is suitable to be used in computer aided design environments such as Rhinoceros 3D during design stages, where the form finding can be evaluated together with other studies in a design context.
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| 6. |
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| 7. |
- Alic, Vedad, et al.
(author)
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Generating initial reinforcement layouts using graphic statics
- 2018
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In: Proceedings of the IASS Symposium 2018 : Creativity in Structural Design - Creativity in Structural Design.
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Conference paper (peer-reviewed)abstract
- A key step to the strut-and-tie method is the selection of an appropriate truss model, due to the static indeterminacy of reinforced concrete there are often several suitable models possible. A method for automatically generating a suitable truss model by using graphic statics is presented. Optimal layouts are found by minimizing the total load path. A formulation of constraints suitable for generating an initial strut-and-tie model confined to an arbitrary polygon with holes is also presented. The performance by using derivative based and derivative free solvers is compared. The method is applied to several examples and the results are compared to existing methods from literature as well as to the principal stress patterns based on finite element analysis. All of the presented examples yield good results and the optimal layouts found can be used as a starting point for further design with the strut-and-tie method.
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| 8. |
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| 9. |
- Alic, Vedad
(author)
-
Numerical Methods for Conceptual Structural Design
- 2016
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Licentiate thesis (other academic/artistic)abstract
- Conceptual design is the first phase in the design process in which all the requirements and design objectives are synthesized into conceptual alternatives. In practice today, major decisions regarding the buildings geometry, massing, and overall form are usually made during the first phase. Considering structural performance requirements during conceptual design enhances interdisciplinary interaction, and creates a visual link between form and numeric performance evaluations, reducing work on poorly performing solutions. To include structural performance in conceptual design requires, amongst other things, the availability of tools such as simulation software, suitable for conceptual studies.The aim of the research is to develop new efficient methods and procedures for supporting an interactive and iterative design process that includes engineering aspects. By integrating engineering knowledge and physical aspects in the developed tools, a more efficient and betteradapted design process can be obtained. Modeling tools for conceptual studies should encourage creativity and be capable of interactively modifying the model in a sketch-like fashion once it has been created. Supporting an interactive and iterative design process, requires new interaction models and numerical approaches in the tools used.The research has focused on two different areas, were the first is related to conceptual studies for reducing ground borne wave propagations in an urban scale. A tool is developed for simulating forms with masses placed on top of soil in an urban scale and studying the resulting effect that the forms have on the propagating waves. The tool uses the finite element method and studies the vibration reduction effects in the frequency domain. Paper A presents the tool and draws some conclusions related to the levels of vibration reduction for various patterns, showing that some patterns are effective in mitigating the incoming vibrations. The approach in the tool makes it possible to obtain results in minutes, allowing the user to generate many alternative proposals quickly, and act as an aid in brainstorming sessions.Papers B and C focus on a recent extension of the finite element method, called isogeometric analysis. The implementation of isogeometric analysis with membrane elements for form finding of efficient shapes for shells is presented. The dynamic relaxation method is used for finding the static solutions. The method is employed directly on design geometry, which is described by non-uniform rational b-splines (NURBS), without the need for any further discretization. Paper B investigates various selections of mass and damping for the dynamic relaxation method with NURBS based membrane elements. The results are used to implement two plug-ins for the computer aided design applications Rhinoceros 3D and Grasshopper 3D, of which the former is presented in paper C. The method describes form found geometries well with very few elements and can be used to explore different efficient shapes for shells very rapidly and directly in design software, and is thus suited for design explorations.
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| 10. |
- Alic, Vedad, et al.
(author)
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NURBS based form finding of efficient shapes for shells
- 2016
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In: Proceedings of 29th Nordic Seminar on Computational Mechanics – NSCM29.
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Conference paper (other academic/artistic)abstract
- This paper presents ongoing research on using non-uniform rational b-splines(NURBS) based isogeometric analysis for form finding of efficient shapes for shells. The form finding is made using dynamic relaxation together with NURBS based membrane elements. The method is employed directly to design geometry, without the need for any further discretization. The method is implemented in two plug-ins for Rhinoceros 3D and Grasshopper 3D. The method describes form found geometries well with very few elements and can be used to find efficient shapes very rapidly and directly in design software, and is thus suited for design explorations.
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