This thesis project is about an associations union and territorial practice through the lens of collaborative construction. The project started with reading a newspaper article about an associations union being evicted from Fältöversten Centrum. The union contains 53 clubs, associations, and interest groups. I interviewed members of the different clubs and associations about what they liked about their old space and what they would like in a new space and outlined a program with them. The site is on the median of Valhallavägen, a boulevard in central Stockholm. The site is poor, given it’s surroundings of noteworthy architecture and significance within the cities grid. I conducted experiments to learn about the site. One being an on-site chair building workshop that contributed its’ resultant chairs to the site for public use. The chairs movements and orientations around the site were documented.  The proposal is a series of small houses spread throughout the site. In order to provide a construction method that’s both appropriate for self builders and spatially interesting, I adapted construction principles discovered during the chair workshop: beams joined by form-cut panels to created 2d trusses. The trusses intend to provide levels of spatial interest in the interior, as well as being a lexicon of the structures principles. the plans of the houses are left intentionally under-designed, the intention being that this leaves the interiors free for appropriation. Spaces include atelier spaces, workshops, makers spaces, meeting rooms, kitchens, auditoriums, greenhouse and a dancehall. The intention of these spaces, their location, orientations, construction and program are to manifest a parallel city, a deconstructed landmark of shared resources and knowledge, and a porous, inclusive, urban image.

After the collapse of the roof structure in Tarfalahallen 2020, great attention has been focused on instability of sub-tensioned glulam roof trusses. Investigations were launched to find the reason for the collapse and the cause was instability in the roof truss that supported the roof. As a result, several similar glulam roof trusses in Sweden have been investigated and reinforced to avoid the fate of Tarfalahallen.Inexperience with instability, negligent design procedure and faulty assumptions is an underlying issue with this type of structure. Complex structures can be difficult to analyze without suitable assumptions which means sophisticated method must be used. Proper analysis must be done before construction.To perform this sophisticated analysis, an engineer can use the finite element method to perform global stability analysis. Simple and computationally cheap models can produce meaningful insight, but in most cases the user must be experienced to understand the implications of the results that the finite element method can produce. There is therefore a need for a more detailed, realistic model that can capture failure and motion and visualize it for the user. This thesis has created such a model in the FE-software Abaqus/Standard.By using a wide variety of elements and element sizes a detailed geometry of the connection between primary beam and compression stud, the behavior of the structural components has been analyzed throughout the loading period of the structure. The critical buckling mode was identified, and the complex non-linear interaction of the connection was tracked when buckling occurs.The thesis can be used as a guideline of how to create a FE-model that captures the intricate behavior of the connection between primary beam and compression stud and be used as the groundwork for more complex models in the future.

Building engineering is called upon to keep up with the pace and challenges of modern design, which aims not only to build higher and greener, but also to fulfill the demands of the growing population and simple human curiosity. The main purpose of this study was to examine the global behavior of a slender and inclined (V-shaped) 300 m high rise building with different structural systems applied. In order to properly evaluate them, four different parametric studies were conducted. These included determining the appropriate inclination angle and the geometry of a simple beam system and later comparing fourteen different structural systems, namely trusses, diagrids, Tubed Mega Frames and moment frames. Parallel to this, a further investigation was made on a shell and beam element model, in order to assess the simplifications made and to control the obtained results. This study was based on various simulations in Finite Element Analysis programs, primarily ETABS, but also SAP2000 and Autodesk Robot Structural Analysis. The modelling included the definition of geometry and applied loads and results in extracting the desirable forces and deformations. Additionally, the automatic design for structural members was used for the purpose of a comprehensive study of the chosen structural systems. The designed structures were subjected to static analysis (dead, live, wind, seismic load), dynamic analysis (response spectrum and time history function) and nonlinear P-delta effect. A buckling analysis was also performed to determine the modes and associated load factors for buckling. In the end, the structural response in terms of displacement and acceleration was compared. The inclination angle study set the defining angle at 10° from vertical, with respect to the serviceability limit deflection. Comparing alternative truss geometries in a 2D parametric study resulted in the choice of four different systems (X, N, K and W trusses). In the 3D analysis, the chosen truss systems, together with three variations of diagrid systems, and seven Tubed Mega Frames with two moment frame structures were further analyzed. In both groups, the mass and the material of the systems were kept similar and the comparison was basically based on the obtained maximum displacement and natural periods of the buildings. The shell and frame model comparison gave a difference in displacements between 0 and 12%. Finally, the comprehensive study of the Tubed Mega Frame, X truss and diagrid structures showed that these buildings were performing similarly to vertical buildings with a top story displacement within the suggested limits (less than 673 mm). Further investigation should be made concerning the acceleration under synthetic earthquake, which exceeded the suggested norms, as well as the connecting nodes between the trusses and the inclined columns. The outcome of this study implied the possibility of construction and usability of inclined, slender, tall buildings with respect to the Ultimate Limit State and the Service Limit State, as specified in the American standard, ASCE 7-10, and opened new possible issues for further research.

Global awareness and preservation have spurred increasing interest in utilizing environmentally friendly materials for high-performance structural applications. Biocomposites pose an appealing solution to this issue and are characterized by their sustainable lifecycles, biodegradable qualities, light weight, remarkable strength, and exceptional stiffness. Many of these structural qualities are found in applications that exhibit flexural loading conditions, and this study focuses on improving the bending performance of engineered biocomposite structures. The current application of biocomposites is increasing rapidly, so this expanding research explores other natural constituent materials for biocomposite structures under flexural loading. The renewable material investigated in this study was experimentally and numerically validated by optimizing the mechanical characteristics of bamboo fibers in biocomposite structures under flexural loading conditions through various thermal and organic chemical treatment methods. Therefore, bending performance of a biocomposite truss and I-beam are analyzed to demonstrate the benefits of utilizing optimally treated bamboos in their design. To accomplish this goal, the first task consisted of treating bamboos by thermal and chemical means to determine the resulting effects on the compressive and tensile mechanical properties through experimental testing. Results indicated a significant improvement in strength, stiffness, and weight reduction. An extensive analysis determined the optimal treatment method that was utilized for flexural loading conditions. The second task entailed studying the flexural behavior of the optimally treated bamboo in two geometric configurations, a hollow cylinder and veneer strip, to determine the resultant properties for the truss and I-beam structure. The effect of node location on flexural performance was also studied to establish design guidelines for the applied structures. Bending tests indicated that node location affects the strength and stiffness of the hollow cylindrical configuration but has minimal effects on the veneer strip. Observations discovered by this study were employed into the designs of the applied structures that yielded excellent mechanical performance through flexural testing. The final task required conducting a finite element analysis in Abaqus/CAE on the performance of each structural application to validate experimental results. A conclusive analysis revealed good agreement between the numerical method and experimental result.

A Displacement Based Optimization (DBO) approach was applied to truss design problems with material nonlinearities, to explore feasibility and verify efficiency of the approach to solve such problem. Various truss sizing problems with holonomic (path-independent) elastoplastic laws were investigated. This type of material nonlinearity allows us to naturally extend the linear elastic truss sizing in the DBO setting to nonlinear problems. A computer program that uses the commercially available optimizer DOT by VR&D and IMSL Linear Programming solver by Visual Numerics was developed to solve this type of problems. For comparison, we chose an important class of minimum-weight truss design problems, where holonomic linear strain hardening behavior was used. Additional examples of optimum design of trusses with elastic perfectly plastic material response that could be easily solved by Limit Design approach using linear programming were investigated for comparison. All demonstrated examples were tested successfully using the DBO approach. Solutions of comparable examples were consistent with the available results by other methods. Computational effort associated with the DBO approach was minimal for all the examples studied. Optimum solutions of several examples proved that the DBO approach is particularly suited for truss topology design where removal of truss members is essential. / Master of Science

No description available.

No description available.

Many buildings today primarily serve the purpose of being envelopes that separate theindoor climate from the outdoors, for a large open area. Examples of these buildings arehall buildings of different sorts. In climates where the snow load often exceeds the deadload, like in Sweden, it can be hard to construct a budget-friendly yet strong roof structurefor these halls, especially if a span above 40 m is required. One solution that has gained popularity is the tie rod truss. Oftentimes it is not a real truss,but rather a beam that is equipped with one or more tie rods and one or more compressionstruts. The struts, which connect to the tie rods that run from one end of the roof to theother, support the main beam. This way, the tie rods can decrease the moment load on thebeams by carrying a tensile force. However, this results in an increased compressive loadon the beams. The large compressive forces in conjunction with the often slender beamsections can lead to instability out of the truss plane, and ultimately collapse. This is whathappened to the sports hall Tarfalahallen in 2020 in Kiruna, Sweden. The tie rod truss is an important structure; it is relatively cheap, saves material and is strongin the truss plane. But the instability problems can deter its use. The aim of this study istherefore to explore the different factors that could influence the stability of the structureand to what extent, by studying critical loads and the utilization of all structural elements. The study was performed by analyzing a finite element model of a real tie rod truss thattoday exists in a sports hall in Sweden. The analyses were done for different values of many parameters. The results were then extracted and processed such that the critical load and the utilization were plotted against the tested parameter values. The analysis and results processing were performed in an automated process that the author created himself. The results show that the stability of the model is strongly influenced by (1) the rigidity ofthe joints between beams and struts, (2) the rigidity of the joints between beams and roofing material and (3) the vertical position of potential stabilization systems that actperpendicularly to the truss plane. Pretension of the tie rods had a large effect on themaximum utilization and how it varies along the beams. Any potential reinforcement measure must be cost-effective, and therefore should addressthe three influential properties above. One suggestion is to add sideway bracing as close tothe joints between the struts and beams as possible. / Det finns många hus idag som byggs i syfte att vara klimatskal för en stor, öppen yta. Exempel på sådana hus är hallbyggnader av olika slag. I länder som Sverige, där snölasten många gånger är större än egentyngden, kan ett billigt men hållfast tak vara svårt att konstruera för dessa hallar, särskilt om spännvidder över 40 m krävs. En lösning som blivit populär är den underspända takstolen. I princip är det ett par balkar som skarvats så att de bildar en sadeltakstol eller en lång rak balk (pulpettakstol), och som stöttas av mellanstöd och stållinor (dragband) som löper från den ena balkänden till den andra via mellanstöden. Stållinorna kan då avlasta balkarna från momentbelastning genom att bära en dragkraft. Men samtidigt ökar tryckkraften i balkarna. De stora tryckkrafterna, i samband med att balktvärsnitten ofta görs väldigt slanka, kan leda till instabilitet ut ur takstolsplanet och därmed kollaps. Detta skedde i Tarfalahallen i Kiruna år 2020. Den underspända takstolen är en viktig konstruktion eftersom den är relativt billig,materialbesparande och väldigt hållfast i takstolsplanet. Men instabilitetsfenomenen kanförhindra fortsatt användning av konstruktionen. Därför undersöks i detta arbete vilka faktorer som kan påverka instabiliteten och i vilken grad, genom att studera kritiska laster och utnyttjandegrader. Studien utfördes genom att analysera en finita elementmodell av en verklig underspändtakstol som idag finns i en svensk gymnastikhall. Analyserna gjordes för olika värden på ett stort antal parametrar. Utdata från finita elementprogrammet extraherades därefter och bearbetades så att utnyttjandegraden i alla ingående bärverkselement beräknades. Sedan plottades dessa resultat mot de olika parametervärdena som testats. Analyserna och påföljande bearbetning utfördes i en automatiserad process som författaren själv skapade. Resultaten visar att modellens stabilitet är starkt beroende av (1) styvheten i förbindelsenmellan balk och mellanstöd, (2) styvheten i förbindelsen mellan balk och sekundärbärverkoch (3) det vertikala läget av eventuella stabiliseringssystem som verkar vinkelrätt mottakstolsplanet. Förspänning av stållinorna hade en betydlig inverkan på den maximalautnyttjandegraden och hur denna varierar längs balkarna. Eventuella förstärkningsåtgärder måste vara kostnadseffektiva, och därmed måste dessagälla de tre egenskaperna ovan. En åtgärd som föreslås sidostagning så nära stöttornasinfästningar som det går.

Isostatic frameworks are statically determinate trusses that are self contained (Le. they exist independent of support or foundation). Isostatic frameworks have been widely used as supporting structures, and recently they have been used as the structure for parallel manipulators. These truss-based manipulators could potentially solve the problems facing conventional manipulators and could make the design of high-degree-of-freedom manipulators feasible. The rigorous scientific study of isostatic frameworks and manipulators based on their structure has been limited. Recent developments in the design of large space structures and truss-based manipulators, however, demand rigorous design and mathematical tools. This dissertation provides a general theory for the design of structures based on frameworks and methods to analyze the kinematics of truss-based manipulators. The objective of the first part of this dissertation is to solve the problems of identification, generation and classification of isostatic frameworks in greater depth than in any past work in this area. Original methods are discussed for the enumeration and generation of isostatic frameworks. The first part also presents an original method to determine the geometry of general frameworks and an improved method to find the forces in their members. The determination of geometry and forces are critical areas in structural design. The second part of this dissertation presents a case study on one of the candidates for manipulator applications, the double-octahedral manipulator. The kinematic analyses of the double-octahedral manipulator includes methods to perform forward and inverse kinematic analysis, velocity and acceleration analysis, singularity analysis and workspace analysis. The closed-form solution to the inverse analysis presented herein is a major breakthrough in the development of the double-octahedral manipulator. Other analysis, such as velocity and acceleration, singularity, and workspace, depend on the inverse solution. It is believed that these solutions will help narrow the gap between theory and application of truss-based manipulators. The determination of singularities and works paces are application of recent ideas of other researchers. However, original implementations of these ideas have yielded astonishing results. The Jacobian and Hessian matrix presented in this dissertation should help in developing the control scheme for this device. C-Ianguage program codes for several of the methods are also provided. The methods have been tested based on the results obtained from these programs. The position analysis algorithms have also been tested on real hardware. Some of the methods developed here have been successfully employed for simulated and experimental vibration control studies. / Ph. D.

Notched stringer segments spliced with metal connector plates (MCPs) and pallets with spliced stringer(s) were tested in static bending in order to determine the relative effectiveness of different stringer splicing methods and under what conditions the process is or is not effective. The species tested were oak, southern yellow pine, yellow-poplar, and two combined species - oak and yellow-poplar, and oak and southern yellow pine. The metal connector plates used were 3 x 4-inch, 3 x 6-inch truss plates, and a 3 x 4-inch plug plate. The splice methods tested were a vertical splice (VS), a 45° angle splice (AS), and a vertical splice with -inch gap between segments (VSG). The results of bending tests of these specimens were compared to non-spliced whole stringers and pallets containing whole stringers. Multiple comparison, statistical methods were used to analyze all test data. An analysis of the failure locations and types of specimens was also used to analyze test results. Vertical spliced stringers with 3 x 4 and 3 x 6 inch truss plates were the best designs of those tested. Spliced stringers were an average of 112% and 74% bending strength and stiffness of new non-spliced stringer. These plates were an average of 26% stronger and 13% stiffer than the 3 x 4 inch plug plate splice stringer. There was no difference between the performance stringers spliced with 3 x 6 and 3 x 4 inch truss plate. An angle splice design and the addition of 1.25 x 6 inch truss plate on the tension side of spliced stringer did not appear to improve the strength and stiffness. A gap between segments significantly reduces splice strength and stiffness by an average of 35% and 16% respectively. When mixing stringer segment species, the performance is determined by the weaker segment. The average strength and stiffness of pallets containing spliced stringers were similar to that of pallets with whole stringers, however the variation in performance was greater when notched stringer pallets contain splices. / Master of Science