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The subject of the presented work is the optimization of grid structures over some predefined free form shape, with the goal of generating\r\na stable and statically efficient structure. It is shown how combining design and FEM software in an iterative, Genetic Algorithms based, optimization process, stress and displacements in grid shell structures can be significantly reduced, whereby material can be saved and stability enhanced.\r\nWithin this research, design and static analysis software are combined in order to perform a statical optimization of grid shells,generated over a given free form surface. A plug-in for Rhinoceros 3D (software based on NURBS [44] geometry representation) is developed, that uses Genetic Algorithms as an optimization method and implements automated iterative calls to Oasys GSA (commercial FEM static analysis software) in order to generate a statically optimal grid shell. To make this possible, within this research some new types of automatic grid generation are developed. Voronoi\r\ndiagrams [11] were used together with the adapted Force-Density method [38] to develop a new type of grid structure that we called Voronax. In the presented work it was shown that, using the same free form surface, and using the same number of joints and structural members, we can generate much more efficient grid shells,\r\nwhen compared to the standard (uniform) grid structures, simply by modifying the structural grid, i.e., rearranging the structural members of the grid shell.\r\nThe work presented offers an explanation of the entire method and how it can be constructed. The results of the experiments are there to prove its efficiency and credibility. Once it is proved that the method works, its application can take various forms and be left to the creativity of the user and the requirements of the\r\nspecific project.", "isbn" : "978-3-922302-32-2", "language" : "eng", "bibtexKey": "dimcic2012structural" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/226f1ec9390a0245dacb4b4e464bbec11/petraheim", "tags" : [ "2017","acttively","analysis","bent","diss","dissertation","engineering","form-finding","forschungsbericht","grid","itke","li","plate","segmental","shell","structural","structure","timber" ], "intraHash" : "26f1ec9390a0245dacb4b4e464bbec11", "interHash" : "b63b7f1729a68f2d49cf78422af4e9de", "label" : "Timber Shell Structures: Form-finding and Structural Analysis of Actively Bent Grid Shells and Segmental Plate Shells", "user" : "petraheim", "description" : "", "date" : "2020-06-23 16:38:28", "changeDate" : "2021-07-01 13:04:36", "count" : 2, "pub-type": "phdthesis", "series": "Forschungsberichte aus dem Institut für Tragkonstruktionen und Konstruktives Entwerfen","publisher":"Stuttgart: Institut für Tragkonstruktionen und Konstruktives Entwerfen","address":"ITKE, Stuttgart, Germany", "year": "2017", "url": "", "author": [ "Li. Jian-Min" ], "authors": [ {"first" : "Li.", "last" : "Jian-Min"} ], "editor": [ "Jan Knippers" ], "editors": [ {"first" : "Jan", "last" : "Knippers"} ], "volume": "42","abstract": "Shell structures are structurally efficient but difficult to manufacture and thus expansive. Actively bent grid shells and segmental plate shells could be alternatives. The first kind utilizes bended members to form a continuously curved geometry and thus reduce the complexity of the joints. The second kind utilizes the stability inherited in trivalent geometries to be able to build a shell without using bending stiff joints. Both these two types of timber shell structures could largely reduce the construction cost. That is why they are chosen as the research topics. The dynamic relaxation method (DR) is applied in this research as an important numerical method. It is used as the fundamental base for developing the form-finding tools of both actively bent grid shells\r\nand the segmental grid shells. A solver capable of the structural analysis of beam system is also developed here based on DR. Through the text, we show that DR could handle not only form-finding problems but also geometrically nonlinear analysis.\r\nThe dissertation consists of four parts. Part I is the introduction. Part II and Part III present both the form-finding and analysis techniques of these two types of timber shell structures. 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Jian-Min" ], "authors": [ {"first" : "Li.", "last" : "Jian-Min"} ], "editor": [ "Jan Knippers" ], "editors": [ {"first" : "Jan", "last" : "Knippers"} ], "volume": "42","abstract": "Shell structures are structurally efficient but difficult to manufacture and thus expansive. Actively bent grid shells and segmental plate shells could be alternatives. The first kind utilizes bended members to form a continuously curved geometry and thus reduce the complexity of the joints. The second kind utilizes the stability inherited in trivalent geometries to be able to build a shell without using bending stiff joints. Both these two types of timber shell structures could largely reduce the construction cost. That is why they are chosen as the research topics. The dynamic relaxation method (DR) is applied in this research as an important numerical method. It is used as the fundamental base for developing the form-finding tools of both actively bent grid shells\r\nand the segmental grid shells. A solver capable of the structural analysis of beam system is also developed here based on DR. Through the text, we show that DR could handle not only form-finding problems but also geometrically nonlinear analysis.\r\nThe dissertation consists of four parts. Part I is the introduction. Part II and Part III present both the form-finding and analysis techniques of these two types of timber shell structures. The last part is the conclusions.", "isbn" : "978-3-922302-42-1", "language" : "eng", "bibtexKey": "jianmin2017timber" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/24227971b3516b084125d1b37e8dcbac0/itke", "tags" : [ "2012","algorithm","architecture","based","dimcic","diss","dissertation","engineering","forschungsbericht","from:petraheim","genetic","grid","itke","optimisation","optimization","shell","structural" ], "intraHash" : "4227971b3516b084125d1b37e8dcbac0", "interHash" : "62f2af1051cae336f6d6ec10e72fed49", "label" : "Structural Optimization of Grid Shells based on Genetic Algorithms", "user" : "itke", "description" : "", "date" : "2020-05-22 14:20:03", "changeDate" : "2020-06-24 11:41:45", "count" : 2, "pub-type": "phdthesis", "series": "Forschungsberichte aus dem Institut für Tragkonstruktionen und Konstruktives Entwerfen","publisher":"Stuttgart: Institut für Tragkonstruktionen und Konstruktives Entwerfen","address":"ITKE, Stuttgart, Germany", "year": "2012", "url": "", "author": [ "Milos Dimcic" ], "authors": [ {"first" : "Milos", "last" : "Dimcic"} ], "editor": [ "Jan Knippers" ], "editors": [ {"first" : "Jan", "last" : "Knippers"} ], "volume": "32","abstract": "In the 21st century, as free form design gains popularity, free-form grid shells are becoming a universal structural solution, enabling merger of structure and facade into a single layer - a skin [31]. The subject of the presented work is the optimization of grid structures over some predefined free form shape, with the goal of generating\r\na stable and statically efficient structure. It is shown how combining design and FEM software in an iterative, Genetic Algorithms based, optimization process, stress and displacements in grid shell structures can be significantly reduced, whereby material can be saved and stability enhanced.\r\nWithin this research, design and static analysis software are combined in order to perform a statical optimization of grid shells,generated over a given free form surface. A plug-in for Rhinoceros 3D (software based on NURBS [44] geometry representation) is developed, that uses Genetic Algorithms as an optimization method and implements automated iterative calls to Oasys GSA (commercial FEM static analysis software) in order to generate a statically optimal grid shell. To make this possible, within this research some new types of automatic grid generation are developed. Voronoi\r\ndiagrams [11] were used together with the adapted Force-Density method [38] to develop a new type of grid structure that we called Voronax. In the presented work it was shown that, using the same free form surface, and using the same number of joints and structural members, we can generate much more efficient grid shells,\r\nwhen compared to the standard (uniform) grid structures, simply by modifying the structural grid, i.e., rearranging the structural members of the grid shell.\r\nThe work presented offers an explanation of the entire method and how it can be constructed. The results of the experiments are there to prove its efficiency and credibility. Once it is proved that the method works, its application can take various forms and be left to the creativity of the user and the requirements of the\r\nspecific project.", "isbn" : "978-3-922302-32-2", "language" : "eng", "bibtexKey": "dimcic2012structural" } ] }