| 1. |
- Adiels, Emil, 1989, et al.
(författare)
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Brick patterns on shells using geodesic coordinates
- 2017
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Ingår i: Proceedings of the IASS Annual Symposium 2017. IASS Annual Symposium 2017; Hamburg, Germany; 25 - 28 September 2017.
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Konferensbidrag (refereegranskat)abstract
- We present two separate strategies for generating brick patterns on free form shells and vaults using geodesic coordinates. The brickwork is specified by a surface on which there is a geodesic coordinate system satisfying the condition for a constant distance between bed joints. The first strategy integrates the generation of the geodesic coordinates in a form finding procedure derived from the geometrical and mechanical properties of a shell. The geometric and structural equations are solved using dynamicrelaxation. The second strategy can be applied on an arbitrary surface separating the form
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| 2. |
- Adiels, Emil, 1989, et al.
(författare)
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Design, fabrication and assembly of a geodesic gridshell in a student workshop
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper describes the design, fabrication and assembly of an 11x11 m gridshell built of plywood laths during a two and a half day workshop in a new undergraduate course about parametric design and digital fabrication. The question was how to use full-scale prototyping to summarize and integrate the learning outcomes in this course. A challenge was how to execute all production during two consecutive days utilizing all 35 students. Exploiting a geodesic grid design, that is curves whose curvature vector is parallel with the surface normal, the gridshell was made of straight predrilled laths that were bent and locked into shape using a sequential erection method. The design was incorporated in a full parametric model including automated design checks and the generation of all necessary production drawings.The workshop and the preparatory work described in this paper was a collaboration between Chalmers, BIG Engineering, Buro Happold and Thornton Tomasetti's CORE studio.
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| 3. |
- Adiels, Emil, 1989, et al.
(författare)
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Internal Force and Moment Surfaces for Shells
- 2024
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Ingår i: Lecture Notes in Civil Engineering. - 2366-2565 .- 2366-2557. ; 437, s. 118-128
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Konferensbidrag (refereegranskat)abstract
- There are 4 fundamental 2nd order tensors in shell theory, firstly the stress and internal moment tensors which are in equilibrium with the applied loads and loading couples, and secondly the rate of membrane strain and the rate of bending tensors which are compatible with the velocity of the shell as it deforms. Shell theory is completed by the constitutive relationships which give the stress and moment in terms of the membrane strain and bending deformation. The fundamental tensors are associated with a number of vectors including the applied loads, loading couples, velocity and angular velocity. We show that the 4 fundamental tensors can all be linearly assembled from vectors using the gradient and also a 3rd order tensor containing the surface permutation tensor and the unit normal. Since a vector describes a surface in 3D space, all these quantities have a graphic significance which can be described using images and models - 3D graphic statics which is the application of differential geometry to statics. We demonstrate that if the moment is described in an appropriate way, using 2 vectors, then internal moments are in equilibrium with zero imposed loads and loading couples, although boundary moments and forces are required. Thus internal moments in shells are ‘redundant’ in the nomenclature of structural theory. For flat plates, one of the redundant moments has to be replaced by a non-redundant moment.
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| 4. |
- Adiels, Emil, 1989, et al.
(författare)
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The architectural application of shells whose boundaries subtend a constant solid angle
- 2024
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Ingår i: Computer Aided Geometric Design. - 0167-8396. ; 111
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Tidskriftsartikel (refereegranskat)abstract
- Surface geometry plays a central role in the design of bridges, vaults and shells, using various techniques for generating a geometry which aims to balance structural, spatial, aesthetic and construction requirements. In this paper we propose the use of surfaces defined such that given closed curves subtend a constant solid angle at all points on the surface and form its boundary. Constant solid angle surfaces enable one to control the boundary slope and hence achieve an approximately constant span-to-height ratio as the span varies, making them structurally viable for shell structures. In addition, when the entire surface boundary is in the same plane, the slope of the surface around the boundary is constant and thus follows a principal curvature direction. Such surfaces are suitable for surface grids where planar quadrilaterals meet the surface boundaries. They can also be used as the Airy stress function in the form finding of shells having forces concentrated at the corners. Our technique employs the Gauss-Bonnet theorem to calculate the solid angle of a point in space and Newton's method to move the point onto the constant solid angle surface. We use the Biot-Savart law to find the gradient of the solid angle. The technique can be applied in parallel to each surface point without an initial mesh, opening up for future studies and other applications when boundary curves are known but the initial topology is unknown. We show the geometrical properties, possibilities and limitations of surfaces of constant solid angle using examples in three dimensions.
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| 5. |
- Adiels, Emil, 1989, et al.
(författare)
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The construction of new masonry bridges inspired by Paul Séjourné
- 2021
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Ingår i: Proceedings of the IASS Annual Symposium 2020/21 and the 7th International Conference on Spatial Structures: Inspiring the Next Generation.
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Konferensbidrag (refereegranskat)abstract
- Masonry arch bridges for rail transport in Europe are still in use 200 years after they were built. Traditional masonry bridges support granular fill which in turn supports the roadway or railway tracks spreading the load on the arch. The stiffness requirements for high speed rail bridges mean that they have to be heavy, in which case masonry bridges supporting fill may again become attractive in comparison with steel or concrete. In this paper we describe the optimization of the bridge geometry to carry the approximately hydrostatic loading from the fill.
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| 6. |
- Adiels, Emil, 1989, et al.
(författare)
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The design , fabrication and assembly of an asymptotic timber gridshell
- 2019
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Ingår i: IASS Symposium 2019 - 60th Anniversary Symposium of the International Association for Shell and Spatial Structures; Structural Membranes 2019 - 9th International Conference on Textile Composites and Inflatable Structures, FORM and FORCE. - 9788412110104 ; , s. 736-743
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Konferensbidrag (refereegranskat)abstract
- This paper describes and discuss the design, fabrication and assembly of an asymptotic gridshell built of plywood laths. The overall question concerns how geometry, structural action, and ecient production can interplay and inform spatial design. The environment is a two-day workshop where architects, engineers and researchers with specialization in structural and digital design cooperate with undergraduate students in a compulsory parametric design and digital fabrication course. The gridshell shape is based on an Enneper surface of threefold rotational symmetry with a boundary baseplate inscribed within a circle of 4.5 m in radius. Utilizing the concept of asymptotic curves, which are surface curves whose osculating plane coincides with the tangent plane of the surface, the structure was built using planar straight laths of plywood made using manually operated drills and saws.
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| 7. |
- Adiels, Emil, 1989, et al.
(författare)
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The geometry of the equilibrium of forces and moments in shells
- 2024
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Ingår i: Meccanica. - 1572-9648 .- 0025-6455. ; In Press
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate that the internal forces and moments in a shell structure can be described by 4 vectors in 3 dimensional space which could be used to express the equilibrium of a shell graphically. The internal forces and moments described by 2 of the 4 vectors actively carry imposed loads and imposed couples, while the other 2 describe ‘redundant’ internal forces and moments that are purely in equilibrium with themselves. Nevertheless redundant stresses and moments are important in controlling internal stresses and satisfying boundary conditions. We show that forces and moments ‘flow’ across a shell in exactly the same way that fluid flows, with a combination of irrotational flow and incompressible flow. The aim is that these ideas can help in the initial design of those shell structures which have to rely on bending moments in addition to membrane action in supporting loads, and also in the interpretation of results from an analysis using the finite element method. We demonstrate the use of the technique for the design of an umbrella structure like those built by Amancio Williams.
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| 8. |
- Adiels, Emil, 1989, et al.
(författare)
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The use of virtual work for the formfinding of fabric, shell and gridshell structures
- 2018
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Ingår i: Proceedings of the Advances in Architectural Geometry conference 2018. - 9783903015135 ; , s. 286-315
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Konferensbidrag (refereegranskat)abstract
- The use of the virtual work theorem enables one to derive the equations of static equilibrium of fabric, shell and gridshell structures from the compatibility equations linking the rate of deformation of a surface to variations in its velocity. If the structure is treated as a continuum there is no need to consider its micro-structure provided that the grid is fine compared to the overall geometry. Thus we can include fabrics, ribbed shells, corrugated shells and gridshells with a fine grid, such as the Mannheim Multihalle. The equilibrium equations are almost identical to those obtained by assuming that a shell is thin and of uniform thickness, but are more general in their application. Our formulation introduces the concept of geodesic bending moments which are relevant to gridshell structures with continuous laths. The virtual work theorem is more general than the energy theorems, which it in- cludes as a special case. Hence it can be applied to surfaces which admit some form of potential, including minimal surfaces and hanging fabrics. We can then use the calculus of variations for the minimization of a surface integral to define the form of a structure. Many existing formfinding techniques can be rewritten in this way, but we concen- trate on surfaces which minimize the surface integral of the mean curvature subject to a constraint on the enclosed volume, producing a surface of constant Gaussian curvature. This naturally leads to the more general study of conjugate stress and curvature directions, and hence to quadrilateral mesh gridshells with flat cladding panels and no bending moments in the structural members under own weight.
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