Space Structures Research Papers - Academia.edu (original) (raw)

2025, International Journal of Space Structures

In this article, a multi-objective optimization is presented to find optimal cable adjustment for statically indeterminate cable structures. Combining a constrained least-square method and the non-dominated sorting genetic algorithm II, a trade-off curve of potential solutions is generated from which a final set of cable adjustments can be chosen by the designer. Optimal solutions are measured against solutions found by a trial-and-error method on the George C. King Bridge case study. Results show that the proposed strategy can successfully find adjustments that significantly reduce overall tension errors, with fewer cables involved.

2025, International Journal of Space Structures

The paper investigates the behaviour of a new type of space structure. The new multi-reciprocal grid (MRG) structure is generated by mutually supporting members with only two members intersecting at any time. Although the concept itself is very old, it has been extended to create a variety of fascinating three-dimensional grids. A scientific basis for the generation of the geometry of these grids is established and discussed. The new structure is demountable, transportable, and quick to re-assemble. The new structure may be particularly useful in emergency situations where rapid construction of shelters is needed.

2025, International Journal of Space Structures

The focus of this article is to identify an analytical description for the layout of a minimum volume truss that is uniformly loaded. Two different span conditions are considered: single and multiple spans. The multiple-span condition is supported at equally spaced locations. The methodology utilized for the solution of the problems takes advantage of Maxwell’s Theorem of Load Paths and the properties of reciprocal diagrams in Graphic Statics. This approach provides considerable insight in the properties of the optimal layouts for the given boundary and loading conditions. In Graphic Statics, the solution to a problem is based on tracing two related diagrams: the form and the force diagram. These obtained graphs can also be viewed as the definition of two dual structures. A force diagram created for a truss structure (form diagram) can be understood as the layout of a (dual) structure with its own loading condition. Therefore, the optimization can be conducted in either space (the f...

2025

Faltbare Raumzellen Untersuchung und kleinmaßstäbliche Anwendung von Faltstrukturen Die Nachfrage nach Raum im architektonischen Sinne ist heutzutage größer den je. Auch wenn Wohnraum einen permanenten Charakter entwickelt hat aufgrund der Sesshaftigkeit der Menschen, das war nicht immer der Fall. In der Entwicklungsgeschichte der Menschheit waren wandelbare Strukturen stetige Begleiterscheinungen auf den Entdeckungsreisen deren Nutzer. Auch in unserer Gegenwart sind die Tätigkeiten der Menschen meistens temporär und an gewisse Zeitordnungen gebunden, aber die Strukturen, die sie beherbergen sind permanent mit einer Lebensdauer, die geplante Nutzung, Funktion und die Lebenserwartung der Nutzer weit übertreffen. Architekturgebilde, die zeitweise nicht genutzt werden nehmen permanent den umbauten Raum in Anspruch. Architektur heutzutage strebt Anpassungsfähigkeit zu unterschiedlichen Zuständen und den Bedürfnissen deren Nutzer. Ziel der Arbeit ist das Potenzial von wandelbaren Struktu...

2025, International Journal of Space Structures

This paper discusses the conceptual design ofspherical joints in space structures. Known spherical joints were analyzed and six innovative shaping concepts identified. The analysis revealed general tendencies in the shaping of spherical joints over a period of more than 15 years. Also, a surprising "human innovation limit", supposedly related to the limits of "human working memory", was observed. A formal typology of spherical joints is proposed and discussed in the context of innovative design. Three different approaches are considered: traditional. trial-and-error, and application of a computer-oriented innovative design method called Stochastic Form Optimization, and utilization of learning expert system shells for conceptual design.

2025, Pakistan Journal of Engineering and Applied Sciences

Pakistan is currently facing massive energy crisis and requiring huge investment into the power transmission line infrastructure. The longest transmission lines of the country are of 220 kV lines stretching up to 7359 km. The contemporary factored design wind load effects for overhead lattice transmission line tower are evaluated based on the applicable wind load factor, gust response factor and design wind speed as recommended by WAPDA/IEC Specifications (1988), ASCE-74 (1991) and ASCE-7 (2005). The current factors and design wind speed were developed considering linear elastic responses. However, information on the non-linear inelastic responses of such towers under dynamic wind loading and on the structural capacity of towers in relation to the design capacities is lacking. The knowledge and assessment of the capacity curve and its relation to the design strength is important to evaluate the integrity and reliability of these towers. Therefore, in this study, analysis was perform...

2025, International Journal of Space Structures

The Miura Ori is a mechanism composed by a polyhedral deployable surface. It has favorable qualities from engineering prospective that lead the growing interest on it. The present work focuses on its transmission of motion. The mechanism can be represented by spherical 4 bar linkages, and on this account a simple and effective mobility formula is presented. The mechanism having a number of excessive rigid members, it is also possible to remove all or some of them, variously arranged. The changes are included in the calculation of allowable mobility of the system. The resulting tool can be directly used for the design of deployable Miura Ori surfaces with customized shape.

2025, SAE Technical Paper 950875

Numerical simulation of the airbag can be used as a powerful tool in the development of a SIR (Supplemental Inflatable Restraint) system leading to an optimized design and to reduce the development time. However, modeling flattened or folded airbags from the 3D CAD geometry and simulating exact airbag shapes during the deployment is a very complex problem. Especially for the passenger side airbags, generating a flattened and folded mesh from the CAD geometry of the airbag is a very difficult task as these airbags are made of non-developable surface and can not be flattened easily without introducing secondary folds, wrinkling or distortions of mesh. A novel approach called as Initial Metric methodology effectively addresses these problems. The initial metric method uses two types of meshes, A CAD reference mesh and a mapped or a scaled (compressed) mesh constructed from a CAD mesh of the airbag. In the simulation, mapped or scaled (compressed) mesh is used for airbag inflation. An initial metric algorithm calculates internal forces based on geometric differences between the reference mesh and mapped mesh and applies them to the mapped airbag to produce a geometrically correct airbag. The inflation of this geometrically correct airbag is more accurate. Initial metric method can also result in significant (approximately 70-80%) amount of saving in time as mapped meshes are easier to create. Also, the same mapped mesh can be used repeatedly for different simulations with minor changes to CAD or to a reference airbag mesh.

2024, International Journal of Space Structures

Deformations observed on completed systems of space steel structures appear to be much higher than foreseen by standard structural analysis. The proposed technique for resolving this problem uses the steel roof structure of the stadium in Split The procedure may also be applied to systems other than the MERO-type, and warrants the conclusion as to the adequacy of the erected structure, consisting of other types of "industrial assemblages".

2024, International Journal of Space Structures

The emblematic entrance pavilion for the Expo 2017 in Astana is the so-called ‘Sphere’, which with its 80-m diameter is worldwide the largest closed sphere completely covered with glass. The continuous external surface of the Sphere was designed to be built with spherically curved glass panels of parallelogramic shape. The panels are fixed at their perimeter to a structural grid of bent round tubes of steel. This secondary grid is fixed in turn to a coarser primary structural grid at evenly spaced supports. The purpose of this article is to give insight into the constructive geometry design of the Sphere. One of the main targets of ‘geometric design for production’ is to specify the geometry of a construction in such a way that fabrication and installation procedures can be simplified and carried out with a minimum of effort, cost and time. The main measure for the Sphere was to simplify the basic grid by replacing all original three-dimensional free-form curves with series of inter...

2024

Zaha Hadid Architects designed a complex free-form envelope to house the new Heydar Aliyev Cultural Centre in Baku, Azerbaijan. The cultural centre comprises a library, an auditorium and a museum together with other complementary facilities. The architectural space envelope is double layered, that is, it consists of an external and an internal skin with a variable distance in between. A special requirement for the appearance of the cladding panels is the paths of their intermediate joints, which visibly run parallel in one direction, thus accentuating the smoothness of the surface and suggesting a natural flow. The present paper discusses and illustrates how visual, architectural and constructional requirements posed very demanding conditions for designing and modelling the MERO-TSK space structure, which is the actual structural system not only supporting the space envelopes, but a convenient form-giving construction basis to materialise their cladding surfaces.

2024, International Journal of Space Structures

In the last two decades, a renewed interest has arisen, both from the structural engineering and architectural field, to exploit the elegance and structural efficiency of structural surfaces. This paper discusses a project-based course aimed at graduate architecture and civil engineering students to i) develop an in-depth understanding of the basics of surface structures, ii) cultivate relevant numerical and physical form finding proficiency, iii) communicate complex technical issues with peers and iv) problem scope, brainstorm and generate design alternatives for force-modeled systems. Because of the nature of the course and workshop objectives, the evaluation of the effectiveness is qualitative rather than quantitative. Therefore, the findings are supported by students' reactions captured in their course evaluations as well as their chosen careers paths after graduation. Since there is rarely room for the introduction of new courses in an established academic curricula, this p...

2024, International Journal of Space Structures

A nonlinear analysis of an elastic tube subjected to gravity forces and buoyancy pressure is carried out. An update lagrangian formulation is used. The structural analysis efficiency in terms of computer time and accuracy, has been improved when load stiffness matrices have been introduced. In this way the follower forces characteristics such as their intensity and direction changes can be well represented. A sensitivity study of different involved variables on the final deformed pipeline shape is carried out.

2024, International Journal of Space Structures

This article extends the overview relating graphic statics and reciprocal diagrams to linear algebra-based matrix structural analysis. Focus is placed on infinitesimal mechanisms, both in-plane (linkage) and out-of-plane (polyhedral Airy stress functions). Each self-stress in the original diagram corresponds to an out-of-plane polyhedral mechanism. Decomposition into sub-polyhedra leads to a basis set of reciprocal figures which may then be linearly combined. This leads to an intuitively appealing approach to the identification of states of self-stress for use in structural design and to a natural ‘structural algebra’ for use in structural optimisation. A 90° rotation of the sub-reciprocal generated by any sub-polyhedron leads to the displacement diagram of an in-plane mechanism. Any self-stress in the original thus corresponds to an in-plane mechanism of the reciprocal, summarised by the equation s = M* (where s is the number of states of self-stress in one figure, and M* is the n...

2024, Materials (Basel, Switzerland)

Hypervelocity impact (HVI), ubiquitous in low Earth orbit with an impacting velocity in excess of 1 km/s, poses an immense threat to the safety of orbiting spacecraft. Upon penetration of the outer shielding layer of a typical two-layer shielding system, the shattered projectile, together with the jetted materials of the outer shielding material, subsequently impinge the inner shielding layer, to which pitting damage is introduced. The pitting damage includes numerous craters and cracks disorderedly scattered over a wide region. Targeting the quantitative evaluation of this sort of damage (multitudinous damage within a singular inspection region), a characterization strategy, associating linear with nonlinear features of guided ultrasonic waves, is developed. Linear-wise, changes in the signal features in the time domain (e.g., time-of-flight and energy dissipation) are extracted, for detecting gross damage whose characteristic dimensions are comparable to the wavelength of the prob...

2024, International Journal of Space Structures

Crosspiece deployable grids are assemblies formed by groups of bars with two joints at their ends and one or more that lie inward and that can vary their angular position with respect to each other. In practice, this variation means that assemblies can change their form from a folded position, where they occupy very little space, to an unfolded position that is usable as an enclosure or covering. The evolution betwen the two extreme positions of this geometry is determined by compatibility limitations. In this paper, the performance of spherical grids composed of two-way crosspieces is studied. A way of generating them from grids which subdivide the surface of a sphere is also presented.

2024, International Journal of Space Structures

For many years. inflatable structures and membrane-enclosed structures have proved useful for a variety of purposes. Recently, structures that combine highly-pressurised inflatable arch members with light fabric membrane coverings have been developed for use as a variation of such structural systems. These structures could have large openings and be utilised as aircraft hangars, vehicle maintenance shelters, medical aid stations, and emergency shelters following disasters. Two physical models of such structures are tested in this study. First they are placed in wind tunnels at various orientations to the airflow, and their dynamic responses are observed. Then they are subjected to weights simulating snow loads, and the weights are increased until either the material fails or the structure collapses.

2024, International Journal of Space Structures

Automatic joinery has become a common technique for the jointing of beams in timber framing and roofing. It has revived traditional, integral joints such as mortise and tenon connections. Similarly, but only recently, the automatic fabrication of traditional cabinetmaking joints has been introduced for the assembly of timber panel shell structures. First prototypes have used such integrated joints for the alignment and assembly of components, while additional adhesive bonding was used for the load-bearing connection. However, glued joints cannot be assembled on site, which results in several design constraints. In this paper, we propose the use of dovetail joints without adhesive bonding, on the case study of a timber folded plate structure. Through their single-degree-of-freedom (1DOF) geometry, these joints block the relative movement of two parts in all but one direction. This presents the opportunity for an interlocking connection of plates, as well as a challenge for the assembly of folded plate shells, where multiple non-parallel edges per plate must be jointed simultaneously.

2024, Thin-walled Structures

Structural behaviour of timber folded surface systems greatly depends on the connections ability to transfer the occurring forces between the adjacent elements and finally to the supports. This paper focuses on multiple tab-and-slot joints (MTSJ), where digital prefabrication is used to integrate connectors through plate geometry. Multiple plates assembled within a large scale folded surface structure were tested to examine the influence of connection detail type on its global structural behaviour. For this purpose an innovative test setup was devised that approximates uniformly distributed surface load. The connection details used were chosen with respect to preliminary small scale bending tests. Three groups of distinct large scale structures were tested: 1) structures with miter joint detail and adhesive applied along the edges; 2) structures with open slot MTSJ; and 3) structures with closed slot MTSJ. Extensive investigation into the load bearing behaviour and failure propagation for each of the three different types of structures has been conducted. For analysing their feasibility, the tested structures were also reviewed in terms of fabrication time, assembly and on-site construction. The obtained results show that even though adhesively joined structures provide highest structural stiffness, they exhibit multiple disadvantages when considering building scale applications. Open slot MTSJ structures results indicate that these joints cannot provide sufficiently reliable structural behaviour. Structures with MTSJ closed slots show that their joint geometry greatly improves both the ultimate load-bearing capacity as well as stiffness. Furthermore, by transferring the edge occurring forces mainly in compression, they provide additional ductility to the global system. Within the scope of this paper, closed slot MTSJ proved to be a very efficient connection type which can constitute a robust folded structural system made as a multiple assembly of thin timber plates.

2024, International Journal of Space Structures

This article presents a new lightweight construction system for doubly curved shells made from timber plates, inspired by the masonry vaults of Eladio Dieste. The system was developed for a specific case-study project, and general applications to other freeform surfaces are being discussed. The shells are built from two interconnected layers of structural wood veneer plates, using integral through-tenon joints for a fast, precise, and simple assembly. This allows for the construction of a series of differently shaped vaults without a costly mold or support structure. Instead, inclined joints cut with a 5-axis computer numerical controlled milling machine embed the correct location and angle between plates into the shape of the parts. This constrains the relative motions between joined parts to one assembly path. To take advantage of the benefits of such connectors, the constrained assembly paths must be considered in the fundamental design of the system, allowing for the insertion of each plate. This imposes additional constraints in the segmentation process of doubly curved shells. In order to meet the requirements and resolve the multi-constraint system, we use a global, nonlinear optimization approach. Developed as a close collaboration between architects, computer scientists and structural engineers, this article includes an experimental analysis of the influence of parametric modifications in the shape of connectors on their load-bearing performance.

2024, International Journal of Space Structures

Mesh reflectors are always a preferable option for large size deployable antenna reflector over solid surface reflectors due to their flexibility of adjustment in minimum possible space and ability to get deployed to full configuration in space. Maintaining surface properties and accuracy are two important requirements in the design of the mesh reflector for the performance of cable network antenna reflectors. The present work considers the various design approaches for cable mesh configuration of space deployable antenna reflectors. The equal force density shape forming criteria such is applied for obtaining the desired parabolic curvature of the mesh configuration. The ring structure for the deployable mechanism is considered as rigid linkages for designing mesh configuration. A generalized numbering scheme for nodes and cable mesh link is formulated for carrying forward various shapes forming criteria which help in making an algorithm. The algorithm for a better understanding of ...

2024, BUILDER

This research aims to find out how geometry of the supports affects the membrane stress in barrel-vault shaped membranes. A numerical experiment is conducted and the parameters of the support geometry are varied in order to understand... more

2024, PROBLEMY WSPÓŁCZESNEJ ARCHITEKTURY I BUDOWNICTWA

Tensile membrane structures are among favorites when it comes to elegance and wealth of forms of architectural structures. While visual beauty and uniqueness are the first impressions gained by a common observer, designers of tensile membranes understand and appreciate the importance of their structural properties. Like all architectural structures, fabric membranes are also exposed to external loads. External loads cause two main outcomes when acting on tensile membrane structures. These are large deflections and rearrangement of stresses within the fabric of the membrane. While deflections are usually large enough to be visually noticeable by users and can even cause their discomfort, fabric stress is equally important and more frequently a bigger concern for the engineers.
The research presented in this paper deals with fabric stresses of barrel-vault shaped membrane structures. It builds on several previous researches with regard to methodological setup and the procedure of the numerical experiments. Compared to the existing experiments, this one introduces new variations of parameters and loads. A numerical model of typical membrane structure was created and varied in order to find out and clarify the relation between certain structural parameters and fabric stresses under external loads. Several loads were applied to the membrane independently from one another. Resulting fabric stresses were analyzed and discussed. The scientific contribution of the research is in widening the existing knowledge about barrel-vault shaped tensile membrane structures.

2024

This paper introduces a methodology for shape and size optimization of shell structures with variable thickness. A model is defined that reduces the number of variables without losing freedom. Several optimization methods are compared. The method of the Coupled Local Minimizers (CLM) offers the certainty of the identification of the global minimum. This methodology is implemented by using MATLAB and ANSYS. It is used successfully for two instructive examples. 6th International conference on computation of shell and spatial structures IASS-IACM 2008, Ithaca 3 Optimization The shape and size design variables are determined by the model of the shell structure. To complete the formulation for the optimization, an objective function and necessary constraints have to be defined. In this paper, as in Kegl et al. [3] and Lee et al. [4], the objective function is the strain energy E s. The minimization of this function reduces the amount of bending in the shell. As in some load cases an increase of the shell thickness reduces the strain energy, it can be necessary to constrain the volume of the shell.

2024

paper introduces a methodology for shape and size optimization of shell structures with variable thickness. A model is defined that reduces the number of variables without losing freedom. Several optimization methods are compared. The method of the Coupled Local Minimizers (CLM) offers the certainty of the identification of the global minimum. This methodology is implemented by using MATLAB and ANSYS. It is used successfully for two instructive examples.

2024, International Journal of Space Structures

Active bending structures need materials with specific mechanical properties such as large admissible strain and sufficiently high stiffness to prevent buckling. This paper proposes to investigate the materials that could be used following Ashby's selection method. Then it focuses on the most affordable materials which are glass fibre reinforced polymers (GFRP) and natural fibre reinforced polymers (NFRP). As the initial selection is based on short term characteristics, the long term behaviour of fibre reinforced polymers is then addressed based on recent durability studies which are needed to ensure the performance, reliability and safety of a structure. It is shown that, depending on the loading type (tension, bending, torsion, alone or in combination…) and on the nature of the components (fibres, matrix and interfaces), the material undergoes several phenomena reducing its mechanical performances and potentially leading to its failure. Finally, this knowledge of the materials, which allows for a better understanding of the specific relation between the material and the active bending structures, is used to give a framework for stress limitations and recommendations for further optimisation of reliable structures.

2024, Proceedings of the Institution of Civil Engineers

This joint venture research brings together three different fields of research which have led to novel findings: these relate to single-motion erection of irregular lattice gridshells using geometric optimisation techniques for the application of natural fibre-reinforced composites within the context of actively bent elements for curved load-bearing structures. Fabrication tests are carried out for pultruded flat test specimens and tubular sections made from environmentally advantageous composites with flax or sisal fibres and a partially bio-based resin. The flat test specimens with flax fibres exhibit excellent tensile and bending strength properties but the sisal yarns prove more successful for pultrusion. Fibre-reinforced composites (including natural fibre-reinforced plastics) compare favourably to timber and steel for application in actively bent structures where low weight, bending-stress reserves and large curvatures are required. The pultrusion tests also identify serious manufacturing challenges (such as the twisting of sisal fibres), which lead to inconsistent properties and subsequently highlight the need for further investigation. The experimental realisation of a 10 m span irregular lattice gridshell using glass fibre-reinforced plastic was completed as a proof of concept for the suitability of active bending for pultruded fibre-reinforced profiles and also to validate newly developed computational optimisation and construction procedures for irregular gridshell lattices. Construction Materials Volume 166 Issue CM6 Natural-fibre-reinforced plastics in actively bent structures Gengnagel, Lafuente Herná ndez and Bä umer

2024, International Journal of Space Structures

This paper is mainly focused on the numerical methods which are used to calculate realistically the load-carrying behaviour of reticulated shell structures. It is generally assumed that for an economical analysis, aimed at the saving of material, the material non-linearity has to be taken into consideration if dead loads prevail. For this in the context of finite element analysis the stiffness matrices of elastic and elastic-plastic rod elements are presented. In order to ensure the stability of structures it is indispensable to detect limit loads such as snap-through loads and bifurcation loads. Assuming that snapthrough phenomena are quasi static, path-following algorithms can be implemented to trace the load-deflection curves in the postbuckling domain. The testing of the reliability and stability of the algorithms requires a sufficient number of numerical examples. Few will be presented.

2024, The Open Civil Engineering Journal

Introduction:Load bearing capacity of Double Layer Grid Spatial Trusses (DLGST) majorly depend on the structures' imperfections. It is important to analyze the systems with consideration of the influences of uncertainties to ensure the safety of DLGST.Methods:The variation of imperfect members’ positions and initial size of length imperfections (being longer or shorter than the ideal size) were selected as the parameters of the current research. Member length imperfections for both long and short members were randomly taken into account according to the randomly generated numbers. These random numbers were generated using a normal distribution.Results and Conclusion:The effect of imperfection is investigated by repeating the analyses simulations on structures with a stochastic dispersion of the imperfect member position and initial length imperfection. It has been demonstrated that the length imperfections might significantly decrease safety of the structure and also shown that ...

2024

In this paper, we study an innovative class of tensegrity beams, obtained by a suitable assembly of elementary V-Expander tensegrity cells along a longitudinal axis in the threedimensional space. Tensegrity structures, made by struts in compression and cables in tension, are an innovative structures by itself: they are similar only in appearance to conventional pin-joint structures (trusses), and their mechanics is strongly related to initial feasible self-stress states induced in absence of external loads. In particular, from a kinematical point of view these selfstress states avoid the activation of possible infinitesimal mechanisms. By a numerical study, we analyze the feasible self-stress states for lightweight tensegrity beams made by a suitable assembly of V-Expander elementary cells. Moreover, we analyze the influence on the feasible self-stress states of the addition of struts or cables starting from the simplest V-Expander configuration.

2024

One of the important issues that must be taken into consideration in the analysis and design of space frames is the dynamic excitation. The dynamic behaviour of a space frame can be studied first through the vibration characteristics of the structure that is represented by its natural frequencies. One way to view the dynamic structural behaviour of orthogonal square pyramid space grid is to apply dynamic wave load. Finite element analysis package SAP2000 V.15.01 Ultimate was used to study the dynamic behaviour by means of time history function. This paper is aiming to investigate the structural behaviour of orthogonal square pyramid space grid under dynamic load, in which pyramid units with a square base are used. However, the structural behaviour depends on the type of connection. The results showed that for orthogonal square pyramid space grid, the type of connection has no effect on the collapse load and maximum displacement.

2024, International Journal of Space Structures

Proposals for forming various types of bar space structures. which could be used as building structures of different functional purposes are the subjects of this paper. The systems proposed have been developed with the aim of applying them in the design of structural systems for large span covers and highrise buildings. The essential aims of forming large span cover structures is to obtain systems which would allow building these covers using relatively short bars. In the paper some new configuations of such space structures are presented. The most important factor in the design of the structural system of a tall building is the need to provide a comparatively slender structure with appropriate great rigidity. Some proposals of application of space structures as structures of highrise buildings are presented in the paper.

2024, International Journal of Space Structures

Thetype, of spherical .grid plays a significant role in dome coverings realized as bar.constructions, Triangular spherical grids shouidres~;n ble the sphere surface as far as possible. For technological reasons the-grid should be formed ofthe lowest number ofedges of different lengths: Therangeof the necessary changes in the edge lengths should be as low as possible.It would be advantageous to have a grid consisting of the lowest number of triangular faces included between the grid segments, This paper presents a method which makes it possible to determine relatively regular spherical grids. The examples.of the dimension relations of triangular spherical grids determined by this method on the• basts of the selected group of regular polyhedrons were provided. The characteristics of the polyhedrons of a great number of faces. obtained in this way. were also given. In this paper is shown only the basic shape of the method of secondary grid deformation.

2024, Advances in Architectural Geometry 2014

Automatic joinery has become a common technique for the jointing of beams in timber framing and roofing. It has revived traditional, integrated joints such as mortise and tenon connections. Similarly, but only recently, the automatic fabrication of traditional cabinetmaking joints has been introduced for the assembly of timber panel shell structures. First prototypes have used such integrated joints for the alignment and assembly of components, while additional adhesive bonding was used for the load-bearing connection. However, glued joints cannot be assembled on site, which results in several design constraints. In this paper, we propose the use of dovetail joints without adhesive bonding, on the case study of a timber folded plate structure. Through their single-degree-offreedom (1DOF) geometry, these joints block the relative movement of two parts in all but one direction. This presents the opportunity for an interlocking connection of plates, as well as a challenge for the assembly of folded plate shells, where multiple non-parallel edges per plate must be jointed simultaneously.

2024, International Journal of Space Structures

Active bending introduces a new level of integration into the design of architectural structures, and opens up new complexities for the architectural design process. In particular, the introduction of material variation reconfigures the design space. Through the precise specification of their stiffness, it is possible to control and pre-calibrate the bending behaviour of a composite element. This material capacity challenges architecture's existing methods for design, specification and prediction. In this paper, we demonstrate how architects might connect the designed nature of composites with the design of bending-active structures, through computational strategies. We report three built structures that develop architecturally oriented design methods for bending-active systems using composite materials. These projects demonstrate the application and limits of the introduction of advanced engineering simulation into an architectural workflow, and the extension of architecture&#3...

2024

The Big Bang-Big Crunch (BB-BC) optimization algorithm is a new optimization method that relies on the Big Bang and Big Crunch theory, one of the theories of the evolution of the universe. This method is among the heuristic population-based search procedures that incorporate random variation and selection, such as genetic algorithm (GA) and simulated annealing (SA). Alongside the main advantages of these methods, the problems resulting from the improper distribution of candidate solutions cannot be ignored, especially for high-dimensional functions. In this paper a method, namely Audze-Eglais' approach, has been applied to produce population that increases accuracy via homogeneous candidate solutions. Numerical results demonstrate the efficiency of the improved BB-BC method compared to other heuristic algorithm.

2024, Engineering Structures

Due to the complex nature of woven fabrics, biaxial testing forms an integral part of designing lightweight fabric structures. By mimicking the multi-axial stress states the material experiences during its lifetime as a structure, the observed stress-strain relations and derived material parameters are much more representative than uniaxial results. Until recently however, no real standard regarding biaxial testing of fabric materials existed, leading to a significant variation in test and interpretation methods. The publication of EN 17117-1 in 2018 aimed to provide a modern reference which could serve as a framework for the biaxial testing of coated textiles. However, given the historical development within the field of testing fabrics, the code refrains from providing clear rules and rather opts to formulate guidelines and possibilities for various steps of the testing process. As a result, different test contexts and parameter derivation methods can still exist next to one another making inter-laboratory comparison of derived parameters still somewhat of a challenge. During this research a type II polyester-PVC fabric (Sioen T2103) was tested using a number of different test methods. Afterwards linear elastic orthotropic material constants were derived using a number of established mathematical methodologies and assumptions. By comparing the resulting material constants, the influence of the imposed alterations was assessed. This paper describes the testing and derivation procedures, compares the resulting material parameters and proceeds to formulate conclusions based on the observed differences, or lack thereof. These findings not only allow for a more founded comparison of test results between different facilities, but also aids to better understand the impact certain choices in test or derivation methodology can have on the test outcomes. The conducted tests did not only reveal that the variability of the derived material parameters in function of the verified parameters varied in function of the applied load profile, but also allowed for the identification of some relations between alterations in the test/derivation methodology and the resulting material parameters. Observing the effective variability that exists on the derived material parameters shows that the characterisation of coated textiles is still a valuable subject for further research and development. Through this study, and the identified relations between the boundary conditions and the resulting material parameters, we can now assess to a reasonable degree what variation to expect from biaxial tests conducted using various approaches and methodologies. The results presented in this paper not only further highlight the importance of a harmonised methodology for testing fabric materials and derive non-project-oriented material parameters, but also illustrate the need for a broader approach when interpreting these generalised material parameters and applying them in (preliminary) numerical models.

2024, Composite Structures

The integration of bending-active elements in kinematic form-active structures opens new perspectives for the development of transformable architectural applications, introducing new typologies and interesting structural concepts. Structures that combine the use of membrane materials and the concept of active bending are referred to as 'textile hybrids'. The complex interaction between the bending-active boundary elements and the membrane, but also the inherent high flexibility of both the membrane material and the bending-active elements, however, complicate the structural behaviour of the studied transformable textile hybrid. Therefore, an experimental verification of the structure becomes crucial to validate the results obtained through the numerical analysis and to allow a full understanding of the structural behaviour. This paper discusses the experimental setup and investigation of a representative case study and compares the experimental results to the numerically obtained values.

2023, International Journal of Space Structures

In this paper the concept of energy increment map is presented for stability judgement of elastic truss structures under arbitrary dynamic excitations. The modified member theory is adopted to establish the equilibrium equations of the structures. The motion trajectories of structures are numerically solved in time domain and the corresponding stability states are studied according to the energy increment map. Numerical examples show that the method of this paper can lead to satisfactory results in dynamic stability analysis of elastic truss structures.

2023

I shall present the complex surface that I have named the spidron on account of its S-shape and spider-web appearance, and which, in its various transformations, deformations and combinations, has yielded extremely interesting spatial forms and tessellations. The so-called spidron nests, composed of 4, 6, 8 (generally an even number) of spidron arms, form reliefs that can be deformed in an accordion-like fashion. Such nests cut several of the regular and semiregular solids into two mirror-symmetrical halves. With the assistance of professor Emil Molnár, we are attempting to determine and classify all the space-filling shapes using the "Dsymbol" named after the three mathematicians Dress, Delaney and Delone. The first examples of that endeavour are shown using the cube cut in half by a spidron nest. We have discovered several sub-species of the spidron family, constructed from a sequence of a single type (45°, 90°, 45°) or alternating sequences of two different types of isosceles triangles.

2023, Journal of Mechanics of Materials and Structures

Self-similar fractals are geometrically stable in the sense that, when generated by a recursive copying process that starts from a basic building block, their final image depends only on the recursive generation process rather than on the shape of the original building block. In this article we show that an analogous stability property can also be applied to fractals as elastic structural elements and used in practice to obtain the stiffnesses of these fractals by means of a rapidly converging numerical procedure. The relative stiffness coefficients in the limit depend on the generation process rather than on their counterparts in the starting unit. The stiffness matrices of the Koch curve, the Sierpiński triangle, and a two-dimensional generalization of the Cantor set are derived and shown to abide by the aforementioned principle.

2023, Maǧallaẗ al-abḥāṯ al-handasiyyaẗ

Nowadays, single-layer braced domes are widely used by architects and engineers. The strength, economy, and fast installation were the main reasons for spreading this system around the world. The architectural design constraints of a dome impose structural challenges for the design engineer, especially when the span is large, with a small aspect-ratio or heavy design loads. Therefore, the structural engineer looks for different methods to strengthen the singlelayer braced dome. This paper studied three different methods for improving the structural performance of the single-layer braced dome, including the grid-density, the member geometry (size), and the bracing systems with double-layer. A total of 96 finite element models were analyzed and designed using SAP2000 commercial software. Four main types of braced domes were studied, including Schwedler, Ribbed, Geodesic, and Kiewit-6. Two different types of joint connections were modeled (i.e., rigidly-connected and pin-connected). In addition, all models were pin-supported at the bottom ring and subjected to static gravity load only. The results indicated that the joint rigidity had a significant impact on the linear buckling load and a minor effect on the maximum displacement and internal forces. Furthermore, it was found that the increase in grid-density, enlarging member size, or using bracing systems significantly improved the structural performance, but at the expense of increasing the of a single-layer brace dome 's weight.

2023, Facta universitatis - series: Architecture and Civil Engineering

This paper is related to the fact that use of computational tools for form generation, analysis and digital fabrication (CAD/CAM/CAE) in an efficient way enables accurate representation of ideas, simulation of diverse impact and production of rational design solutions. Application of geometrical and numerical computational methods and adoption of performance based priorities enables formal exploration in constrained conditions and improvement of architectural engineering design process. Implementation of advanced technologies in 3D digital design process facilitates production of unconventional complex designs, their verification by construction of physical models and experimental diagnostics, as phase preceding construction of real structure. Within this work concept that provides design of non-standard, context-specific, freeform structure using rapid prototyping technology and 3D optical measurement will be reviewed. The analyzed design solution of roof structure above atrium of ...