Journal articles on the topic 'Space trusse'
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1
Wu, Hui, Wen Feng Du, and Yi Jun Wang. "Failure Mechanisms and Progressive Collapse Judgment Criterion of Space Trusses under Strong Earthquakes." Applied Mechanics and Materials 90-93 (September 2011): 1581–85. http://dx.doi.org/10.4028/www.scientific.net/amm.90-93.1581.
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Aiming at failure mechanisms and judgment criterion of progressive collapse for space trusses, the responses and the failure mechanisms of diagonal square pyramid space trusses, leaning laid pyramid space trusses and orthogonal square pyramid space trusses with circumferential simple supports under different seismic waves were analyzed in this paper. The results show that space trusses have a good performance of earthquake resistance, but progressive collapse occurs easily. Based on the failure mechanisms of space truss, a judgment criterion of space truss is proposed under strong earthquakes, according to the characteristics of energy, displacements and plastic levels of members. The judgment criterion is expressed by judgment coefficient J. When J>6, space trusses tend to be ductile failure, however, When J> 6, space trusses tend to be progressive collapse.
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Silva, Welington V., Ramon Silva, Luciano M. Bezerra, Cleirton A. S. Freitas, and Jorge Bonilla. "Experimental Analysis of Space Trusses Using Spacers of Concrete with Steel Fiber and Sisal Fiber." Materials 13, no. 10 (May 16, 2020): 2305. http://dx.doi.org/10.3390/ma13102305.
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Space trusses are structural systems, generally made of tubes, used worldwide because of their advantages in covering long-span roofs. In addition to having a low cost, the truss weight is relatively reduced. The load capacity of these structures depends also on the strength of their node connection. Connections made with the superposition of flattened tube ends trespassed by one bolt are, generally, known as typical nodes. They are inexpensive but present eccentricities that reduce significantly the strength of such space trusses. To increase the truss load capacity, this research presents the results of an experimental program to reduce the eccentricities of the typical nodes. This reduction is done with a new type of spacer made of encapsulated concrete with steel fiber or sisal fiber. The experimental tests showed that the trusses with typical nodes collapsed under reduced load by local failure due to high distortions at the nodes. The trusses with encapsulated concrete spacer showed good results, with an increase in collapse load of 36% and failure by buckling bars.
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El-Sheikh, Ahmed. "Sensitivity of Space Trusses to Uneven Support Settlement." International Journal of Space Structures 11, no. 4 (December 1996): 392–400. http://dx.doi.org/10.1177/026635119601100406.
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Uneven support settlements are a liability for every structure. However, as space trusses typically span large areas on few outer supports, they are more likely to encounter some uneven settlements. This paper presents an assessment of the sensitivity of space trusses to settlements in various situations with different aspect ratios and supporting conditions, and under different types and magnitudes of uneven support settlement. Additionally, the effect of composite action between a top concrete slab and a steel truss on truss sensitivity to uneven settlements is assessed. The work is carried out on twelve non-composite and composite square-on-square space trusses.
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El-Sheikh, Ahmed. "Sensitivity of Composite and Non-Composite Space Trusses to Member Loss." International Journal of Space Structures 9, no. 2 (June 1994): 107–19. http://dx.doi.org/10.1177/026635119400900205.
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Since double layer space trusses have typically a large number of redundant members, it is frequently assumed that they are quite safe as the loss of one or more members can be accommodated without any noticeable effect on truss overall behaviour. The present study shows that every truss includes a number of critical members, the loss of any of which would cause force distributions that could lead to an overall premature collapse. The sensitivity of space trusses to member loss is clearly identified. The composite action between a top concrete slab and a space truss is also introduced as a means to control truss sensitivity to member loss. Factors that affect this sensitivity such as the truss supporting conditions are also investigated.
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El-Sheikh, A. L. "Numerical Analysis of Space Trusses With Flexible Member-End Joints." International Journal of Space Structures 8, no. 3 (September 1993): 189–97. http://dx.doi.org/10.1177/026635119300800305.
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The conventional procedure for the analysis of space trusses, lattice domes and similar structures, assumes that member-end joints behave as pure pins or, in some cases, as rigid joints. However, experimental studies have shown that these joints typically exhibit some level of flexural stiffness and are therefore flexible (semi-rigid). It was reported that the characteristics of the space truss jointing system play a major role in truss response (see Refs. 1,2,3). The results of experiments conducted on space trusses with rigid or flexible joints produced less brittle behaviour than that found for assemblies with nominally-pinned joints. A nonlinear beam-column element with end springs has been developed to model the actual rotational stiffness of truss member-node connections, and its stiffness expressions are presented in this paper. Incorporation of this element in the numerical analysis of space trusses has led to better predictions of behaviour and strength when compared to the commonly-used two-noded frictionless truss element. This new element was used successfully in the numerical analysis of two non-composite and one composite double-layer space truss, and the results are presented in this paper.
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El-Sheikh, A. L. "Nonlinear Numerical Analysis of Composite Space Trusses." International Journal of Space Structures 9, no. 4 (December 1994): 219–25. http://dx.doi.org/10.1177/026635119400900405.
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The composite action between an upper concrete slab and a double-layer space truss has been shown to have positive effects on the behaviour of such structures. Primarily, the prevention of the typical brittle behaviour of trusses and the introduction of appreciable ductility are among the important benefits. Substantial improvements have been achieved also in both stiffness and ultimate strength. The analysis of composite space trusses requires a careful study especially in the modelling of the shear connection between the concrete slab and the steel truss, involving shear studs mounted on both the nodes and the members of the top chord. Additionally, parts of the concrete slab may be projecting inside the top chord members, and therefore contribute to the shear interaction. This connection, being far from simple, could be modelled using various techniques. The present paper concentrates on these techniques, and numerical results are produced for each case (using a previously-developed and verified finite element program) and compared with the experimental results of a full-scale composite space truss tested earlier. As a conclusion of this work, two methods for preliminary and final design of composite space trusses are recommended for future use.
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El-Sheikh, Ahmed. "Sensitivity of Space Trusses to Sudden Member Loss." International Journal of Space Structures 12, no. 1 (March 1997): 31–41. http://dx.doi.org/10.1177/026635119701200104.
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Space trusses typically contain a large number of members, and possess a high degree of statical indeterminacy. However, a number of members have been identified as critical to truss integrity, with the loss of any of them likely to produce serious strength reductions. Furthermore, when these members are lost suddenly, e.g. due to the failure of a faulty connection or the buckling of a slender member, their forces are shed into the structure in a dynamic manner, leading to yet more severe damage. This paper presents a numerical study on the sensitivity of space trusses to both gradual and sudden member losses. The effect of composite action between a top concrete slab and a space truss in reducing this sensitivity is assessed. Other factors that are also considered in this work include the truss aspect ratio and supporting condition.
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Luo, Ruifeng, Yifan Wang, Zhiyuan Liu, Weifang Xiao, and Xianzhong Zhao. "A Reinforcement Learning Method for Layout Design of Planar and Spatial Trusses using Kernel Regression." Applied Sciences 12, no. 16 (August 17, 2022): 8227. http://dx.doi.org/10.3390/app12168227.
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Truss layout design aims to find the optimal layout, considering node locations, connection topology between nodes, and cross-sectional areas of connecting bars. The design process of trusses can be represented as a reinforcement learning problem by formulating the optimization task into a Markov Decision Process (MDP). The optimization variables such as node positions need to be transformed into discrete actions in this MDP; however, the common method is to uniformly discretize the design domain by generating a set of candidate actions, which brings dimension explosion problems in spatial truss design. In this paper, a reinforcement learning algorithm is proposed to deal with continuous action spaces in truss layout design problems by using kernel regression. It is a nonparametric regression way to sample the continuous action space and generalize the information about action value between sampled actions and unexplored parts of the action space. As the number of searches increases, the algorithm can gradually increase the candidate action set by appending actions of high confidence value from the continuous action space. The value correlation between actions is mapped by the Gaussian function and Euclidean distance. In this sampling strategy, a modified Confidence Upper Bound formula is proposed to evaluate the heuristics of sampled actions, including both 2D and 3D cases. The proposed algorithm was tested in various layout design problems of planar and spatial trusses. The results indicate that the proposed algorithm has a good performance in finding the truss layout with minimum weight. This implies the validity and efficiency of the established algorithm.
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Yan, Xu, Tie Ying Li, and Yun Jing Nie. "The Construction Process Simulation of a Large-Span Rhombic Space Truss Using FEM Analysis." Advanced Materials Research 368-373 (October 2011): 1101–4. http://dx.doi.org/10.4028/www.scientific.net/amr.368-373.1101.
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With the developments of the design theories and the researches, the quantity and the technology of space truss systems in our country have reached the international leading level. In the meantime, the construction methods need to achieve even higher standard. In the article, the rhombic space truss roof of the north station building of Suzhou is selected as the research object. Each step of the sliding and unloading construction is simulated by FEM. The stability and rigidity of the truss are checked in detail. It gives an representative exsample for complicated construction design of large-span space trusses.
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Tabatabaei, Mousa, and Cedric Marsh. "Strengthening Space Trusses by Diagonal Removal." International Journal of Space Structures 8, no. 4 (December 1993): 231–39. http://dx.doi.org/10.1177/026635119300800401.
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Ideally a space truss is composed of bars each of which is suited to the load it carries. In practice, however, it is more convenient to use a limited number of bar sizes, thus only a few of the members will be fully stressed when the maximum load capacity of the space truss is reached. In order to effect a more equitable distribution of forces between chords of equal size such that more chord members are loaded close to their capacity, selected diagonals are removed to control the path followed by the shear forces, and thereby control the forces entering the chords. In this paper the effect of diagonal removal on space trusses is demonstrated and a method for selection of the diagonals whose removal gives optimum increase in the load carrying capacity of a space truss is described.
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Pichugin, S. F., V. P. Chichulin, and K. V. Chichulina. "SPATIAL STRUCTURES OF CLOSED PROFILES." ACADEMIC JOURNAL Series: Industrial Machine Building, Civil Engineering 1, no. 48 (March 27, 2017): 138–43. http://dx.doi.org/10.26906/znp.2017.48.787.
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The article presents a new design of steel space trusses, arches, frames of complex application, the main advantages of which are lightness, durability of plane, cost efficiency, reliability, reduction of construction period and investment cycle, energy savings at manufacture, transportation and construction. Based on the previously performed experimental and theoretic studies, the expediency of using box-shaped section parallel chord trusses has been proved. Therefore, new constructive decisions for light efficient trusses, arches, frames that can be used at erection of civil and industrial objects are presented below. The suggested efficient structure of a steel truss with spatial upper chord, using tubes or rectangular hollow box-shaped sections, steel trifurcate spatial truss construction, spatial arch truss, spatial arch. Considered the use of closed cross-sections for spatial arch elements. It has been revealed that using the two-hinges spatial frame the construction cost of a building can be reduced due to reducing of the basement’s dimensions.
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Sangeetha, Palanivelu. "Analytical Study on the Behaviour of Composite Space Truss Structures with Openings in a Concrete Slab." Civil and Environmental Engineering Reports 30, no. 3 (September 1, 2020): 265–80. http://dx.doi.org/10.2478/ceer-2020-0044.
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Abstract A space truss structural system is a three-dimensional arrangement of linear elements in a pyramid pattern forming a Double Layer Grid (DLG) system. Space trusses are an elegant and economical means of covering larger areas such as roof systems, in a wide variety of applications such as a stadium, aircraft-hanger, assembly hall, etc. The major problem encountered in using the space truss as a roofing system is the sudden failure of the whole structure due to critical buckling of the top chord member. Earlier research has shown that the optimal solution to overcome such a failure is by providing a small thickness of concrete slab over the space truss, so that the space truss with concrete slab (Composite Space Truss) will act as a floor system for the multi-storey building. For better ventilation and lighting in the building, the need for openings in the composite space truss is unavoidable; however, providing an opening in the concrete slab will reduce the load carrying capacity of the structure. The analysis of a composite space truss of size 30m x 30m with all possible locations of openings for four different support conditions was carried out using ANSYS in order to study the load - deflection behaviour. Further, the ductility factor and energy absorption capacity of the composite space truss with different locations of slab openings were compared.
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Savsani, Vimal J., Ghanshyam G. Tejani, Vivek K. Patel, and Poonam Savsani. "Modified meta-heuristics using random mutation for truss topology optimization with static and dynamic constraints." Journal of Computational Design and Engineering 4, no. 2 (November 2, 2016): 106–30. http://dx.doi.org/10.1016/j.jcde.2016.10.002.
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AbstractIn this paper, simultaneous size and topology optimization of planar and space trusses subjected to static and dynamic constraints are investigated. All the benchmark trusses consider discrete cross-sectional areas to consider the practical aspect of manufacturing. Moreover, Trusses are considered with multiple loading conditions and subjected to constraints for natural frequencies, element stresses, nodal displacements, Euler buckling criteria, and kinematic stability conditions. Truss topology optimization (TTO) can be accomplished by the removal of superfluous elements and nodes from the highly hyper static truss also known as the ground structure and results in the saving of the mass of the truss. In this method, the difficulties arise due to the singular solution and unnecessary analysis; therefore, FEA model is reformed to resolve these difficulties.The static and dynamic responses to the TTO problems are challenging due to its search space, which is implicit, non-convex, non-linear, and often leading to divergence. Modified meta-heuristics are effective optimization methods to handle such problems in actual fact. In this paper, modified versions of Teaching–Learning-Based Optimization (TLBO), Heat Transfer Search (HTS), Water Wave Optimization (WWO), and Passing Vehicle Search (PVS) are proposed by integrating the random mutation-based search technique with them. This paper compares the performance of four modified and four basic meta-heuristics to solve discrete TTO problems.Highlights Modifications in four different recently developed meta-heuristics. Use of random mutation based strategy. Implementation on challenging/benchmark truss topology optimization problems. Modifications effective over basic algorithms.
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Hayashi, Kazuki, Makoto Ohsaki, and Masaya Kotera. "Assembly Sequence Optimization of Spatial Trusses Using Graph Embedding and Reinforcement Learning." Journal of the International Association for Shell and Spatial Structures 63, no. 4 (December 1, 2022): 232–40. http://dx.doi.org/10.20898/j.iass.2022.016.
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We consider a truss as a graph consisting of nodes and edges, and combine graph embedding (GE) and reinforcement learning (RL) to develop an agent for generating a stable assembly path for a truss with arbitrary configuration. GE is a method of embedding the features of a graph into a vector space. By using GE, the agent can obtain numerical information on neighboring members and nodes considering their connectivity. Since the stability of a structure is strongly affected by the relative positions of members and nodes, feature extraction by GE should be effective in considering the stability of a truss. The proposed method not only can train agents using trusses with arbitrary connectivity but also can apply trained agents to trusses with arbitrary connectivity, ensuring the versatility of the trained agents' applicability. In the numerical examples, the trained agents are verified to find rational assembly sequences for various trusses more than 1000 times faster than metaheuristic approaches. The trained agent is further implemented as a user-friendly component compatible with 3D modeling software.
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Pîrșan, Dan, and Zeno-Iosif Praisach. "Natural frequencies and mode shapes in zero-force members of a truss." Studia Universitatis Babeș-Bolyai Engineering 66, no. 1 (November 9, 2021): 94–99. http://dx.doi.org/10.24193/subbeng.2021.1.9.
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Trusses are everywhere; they are used in bridges, antenna towers, cranes, even in parts of the International Space Station. And for good reason, they allow us to create strong structures while using materials in very efficient and cost-effective way. Trusses it is essentially a rigid structure made up of a collection of straight members. The type of truss depends on how the horizontal and diagonal beams are arranged.
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Karbaschi, M. E., G. Dehdashti, and A. Fiouz. "Ultimate Load of Barrel-Vault Space Trusses Shaped by Post-Tensioning." International Journal of Space Structures 24, no. 3 (September 2009): 179–89. http://dx.doi.org/10.1260/026635109789867652.
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This paper presents the results of nonlinear analysis to predict the ultimate load of a barrel-vault space truss shaped by post-tensioning. Experimental study on shape formation, load tests to determine the ultimate load of the post-tensioned barrel-vault space truss and individual compression tests on members to determine their buckling load have been carried out in previous research. The nonlinear analysis carried out herein uses the reduced stiffness of various members according to member test results to determine the ultimate load behavior of the model barrel-vault space truss. The paper also presents the ultimate load behavior of large-span barrel-vault space trusses, taking into account the buckling of their members. As a result, it is shown that these structures can be used to cover large spans with sufficient structural stiffness. Lastly, some design aid diagrams are proposed.
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Arun, V., C. F. Reinholtz, and L. T. Watson. "Application of New Homotopy Continuation Techniques to Variable Geometry Trusses." Journal of Mechanical Design 114, no. 3 (September 1, 1992): 422–27. http://dx.doi.org/10.1115/1.2926568.
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A VGT, or Variable Geometry Truss, can be thought of as a statically determinate truss that has been modified to contain some number of variable length members. These extensible members allow the truss to vary its configuration in a controlled manner. Some of the typical applications envisioned for VGTs are as booms to position equipment in space, as supports for space antennae, and as berthing devices. Recently, they have also been proposed as parallel-actuated, long chain, high dexterity manipulators. This paper will demonstrate the use of homotopy continuation in solving the kinematics of relatively complex variable geometry trusses (VGTs) including the octahedron and the decahedron. The procedural aspects are described in detail with the help of examples.
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Nixon, David. "Development studies at NASA on large orbital structures, 1975–1985." International Journal of Space Structures 37, no. 3 (September 2022): 173–86. http://dx.doi.org/10.1177/09560599221120030.
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This paper provides a review of early development studies on structures carried out by NASA and US aerospace contractors between 1975 and 1985 before and during the initiation of the Space Station programme. The studies envisioned very large structures built in orbit using the Space Shuttle, then in the process of entering service. Their original purpose was to function as solar power, antenna and communications platforms. The studies explored the application of automatically-fabricated trusses, then preassembled deployable trusses, and then astronaut-assembled erectable trusses. By the time of the Station’s go-ahead in 1984, a large erectable truss structure formed the backbone of the Station’s design. Erectable trusses were successfully tested on a Space Shuttle mission in 1985 but later abandoned after the Shuttle Challenger disaster in 1986. Taken together, the 1975–1985 development studies have much historical significance as the first generation of ideas about large engineered structures for extraterrestrial applications.
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Granev, Viktor, Nikolay Kelasiev, Emil Kodysh, Nikolay Trekin, and Ivan Terekhov. "Modular frame trusses of buildings." E3S Web of Conferences 97 (2019): 04012. http://dx.doi.org/10.1051/e3sconf/20199704012.
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The paper describes space-planning and structural concept in source-efficient buildings that provides multiple functions of the rooms and large-span space.The main load-bearing structures of two adjacent storeys are metal trusses with parallel chords between which (between top and bottom chords) intermediate storeys are designed and the space between trusses is occupied by the free plan storeys. Bottom and top chords of the truss resist together with floor structure forming two-storey steel-reinforced concrete unit. To calculate value of deformation capacity for nodal connection a numerical experiment focused on modelling a part of building from solid finite elements has been performed. The results of performed analysis are the average values of stiffness of nodal interface of solid floor slab on corrugated deck and truss chords for finite elements KE 55 of typical layout (of flat finite elements). The obtained average values of stiffness were introduced into structural design of flat finite elements. Taking into account flexibility of floor slab that supported by middle trusses for the given structural concept leads to decreased span bending moments and increased support bending moments by 25% compared with hinge support of floor.
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Wang, Yuan Qing, Li Yuan Liu, Da Yi Ding, Yong Jiu Shi, and Hai Ying Wan. "Finite Element Analyses and Design Proposals on the Truss-to-Box Girder Connection Models of Xinqiao International Airport Terminal." Applied Mechanics and Materials 94-96 (September 2011): 724–30. http://dx.doi.org/10.4028/www.scientific.net/amm.94-96.724.
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Hefei Xinqiao International Airport Terminal is a steel structure consisting of long-span rigid frames, with 804m in length and about 161m in width at the widest part. The long-span frame consists of box columns, large curvature beams, tapered box beams and space trusses. The joints between space trusses and box beams named truss-to-box beam connections are the critical parts of the whole structure, because of the discontinuity in geometries and stiffness which result in high stress concentrations and complicated mechanical properties. GJ3-6, GJ3-5 and GJ3-1 of the airport terminal are modeled by ABAQUS. Structure internal forces at six load combinations of bearing capacity limit state are calculated. Lower chords of the landside connections sustain large tensions, while web members of the airside connections sustain large pressures. Since these truss bars are directly connected to cover plate of the box beam, better design details are recommended to reduce the stress concentrations caused by geometrical discontinuity.
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Rashidyan, Saman, and Mohammad-Reza Sheidaii. "Improving double-layer space trusses collapse behavior by strengthening compression layer and weakening tension layer members." Advances in Structural Engineering 20, no. 11 (February 1, 2017): 1757–67. http://dx.doi.org/10.1177/1369433217693631.
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Progressive collapse is a chain of local failures leading to the collapse of either the entire or a part of the structure. The double-layer space trusses are susceptible to progressive collapse due to sudden buckling of compression members. The method of strengthening the compression layer members along with weakening the tension layer members is an effective method for retrofitting the double-layer space truss behavior against progressive collapse. In this study, the method is applied on offset double-layer space truss models with different support conditions, members’ geometrical imperfections, height, and shapes, and the effectiveness in increasing the structure’s ductility and load-bearing capacity is demonstrated. The results show that the method converted the sudden collapse of the structures into a beneficial gradual (progressive) collapse. More specifically, for double-layer space trusses comprising members with similar geometrical imperfection, strengthening the compression layer chords along with weakening the tension layer chords within 30%–40% will significantly improve the ductility and load-bearing capacity. In addition, the results show that the method can decrease the weight of the structures and consequently provide more economical structures.
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Baranyai, Tamás. "On the duality of space trusses and plate structures of rigid plates and elastic edges." International Journal of Space Structures 35, no. 4 (August 24, 2020): 135–46. http://dx.doi.org/10.1177/0956059920947564.
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Dualities have been known to map space trusses and plate structures to each other since the 1980s. Yet the computational similarity of the two has not been used to solve the unfamiliar plate structure with the methods of the well-known truss. This article gives a method to find the forces and displacements of a plate structure with rigid plates and elastic edges, using a dual truss. The plates are assumed to be rigid in their respective planes only and deformable otherwise. The method provided is applicable for both statically determinate and indeterminate structures, subjected to both statical and kinematical loads.
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El-Sheikh, Ahmed. "Approximate Analysis of Space Trusses." International Journal of Space Structures 11, no. 3 (September 1996): 321–30. http://dx.doi.org/10.1177/026635119601100304.
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For decades, space trusses have been designed using approximate numerical methods that are based on simplified truss layouts. Although these methods still rely on using computers, their demand on computer time and resources is considerably less than that associated with full finite element analyses. However, as the last decade has seen a revolutionary advance in computer technology, full F.E. analyses are no longer time consuming or expensive, and as a consequence, the old approximate analysis methods have become almost obsolete. Now the need has shifted towards methods that are quick and easy to use, and yet accurate enough for preliminary designs and as a check on F.E. analysis results. In practice, a suitable method is adopted for a first choice of member sizes, then the results obtained are fed into a cycle or more of F.E. analysis and redesign until a final design is reached. Following a discussion on the required characteristics of modem approximate methods of space truss analysis, two examples of these methods are presented and assessed in this paper.
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Freitas, Cleirton A. S., Mucio M. S. Nobrega, Édipo A. Bezerra, and Otávio R. O. Cavalcante. "Polymer Composite with Sisal Fiber Used for Node Reinforce in Space-Truss with Stamped Connection." Applied Mechanics and Materials 719-720 (January 2015): 202–5. http://dx.doi.org/10.4028/www.scientific.net/amm.719-720.202.
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Space trusses are three-dimensional structures made of steel bars very frequently used at the roof construction. The bars, with tubular section, are linking in the 3D form by connections. There are several types of connections to attach these members. The most economical connection is the staking end-flattened connection, also called typical node. The reduced cost and the fast assemblage of the truss are among their advantages. However, such connections present disadvantages like eccentricities and stiffness weakening of the tubular members. This research presents suggestions of reinforcement and constructive correction in the connection in order to increase its capacity. The base for this is the reduction of the eccentricity in typical node applying the spacer. This spacer was made by polymer composite with sisal fiber. In this work was developed experimental lab tests in prototypes with fifty four meters square of area. The results show an increase of 26% for collapse in the truss load carrying capacity when the suggested changes proposed in this article are used for the staking end-flattened connections.
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de Souza, Alex Sander Clemente, and Roberto Martins Gonçalves. "Mechanism of Collapse of Space Trusses with Steel Hollow Circular Bars with Flattened Ends." International Journal of Space Structures 20, no. 4 (December 2005): 201–9. http://dx.doi.org/10.1260/026635105775870279.
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This paper presents the results of experimental analysis of space trusses using steel tubular bars with flattened ends. The connections are formed by overlapped bars connected by single bolt. Such system has been used due to the low cost and assembly facilities. The behavior and collapse modes were determined by experimental analysis on six space trusses with 1.5 m height and spans of 7.5 m × 7.5 m and 7.5 m × 15 m. Structures with steel nodes in the top corner and supports points were also tested. The structural collapse was caused by either connection collapse or yielding in the bar ends. Traditional theoretical analysis models (linear truss model) are not suitable for these structures.
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Tejani, Ghanshyam G., Vimal J. Savsani, Vivek K. Patel, and Poonam V. Savsani. "Size, shape, and topology optimization of planar and space trusses using mutation-based improved metaheuristics." Journal of Computational Design and Engineering 5, no. 2 (October 12, 2017): 198–214. http://dx.doi.org/10.1016/j.jcde.2017.10.001.
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Abstract In this study, simultaneous size, shape, and topology optimization of planar and space trusses are investigated. Moreover, the trusses are subjected to constraints for element stresses, nodal displacements, and kinematic stability conditions. Truss Topology Optimization (TTO) removes the superfluous elements and nodes from the ground structure. In this method, the difficulties arise due to unacceptable and singular topologies; therefore, the Grubler's criterion and the positive definiteness are used to handle such issue. Moreover, the TTO is challenging due to its search space, which is implicit, non-convex, non-linear, and often leading to divergence. Therefore, mutation-based metaheuristics are proposed to investigate them. This study compares the performance of four improved metaheuristics (viz. Improved Teaching–Learning-Based Optimization (ITLBO), Improved Heat Transfer Search (IHTS), Improved Water Wave Optimization (IWWO), and Improved Passing Vehicle Search (IPVS)) and four basic metaheuristics (viz. TLBO, HTS, WWO, and PVS) in order to solve structural optimization problems. Highlights Improvements in four recently designed metaheuristics. Use of random mutation-based search technique. Applications on challenging/benchmark problems of simultaneous size, shape, and topology optimization of truss structures. Improvements effective over basic metaheuristics.
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Marufiy, A., and E. Rysbekova. "Specific Design Solution for Covering Large Areas With Spatial Metal Truss." Bulletin of Science and Practice 7, no. 12 (December 15, 2021): 160–68. http://dx.doi.org/10.33619/2414-2948/73/22.
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. The relevance of the research results given in the article lies in the need to apply new constructive solutions for large spaces. The purpose of this work is to search for new design solutions for covering large areas with spatial metal trusses. The problems of forming a computational spatial bar finite element model of a steel spatial truss of a dome-shaped radial-ring structure were solved. The calculation of the spatial system was carried out using the finite element method of current computer programs, new constructive solutions for spatial metal trusses were adopted. The stress-strain states of the model from a given load have been determined. The calculation of the spatial system was carried out using the finite element method of current computer programs, new constructive solutions for spatial metal trusses were adopted. The research results can be used in the formation of architectural and structural solutions of a building using a new structural arrangement of the elements of a spatial truss.
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Marčiš, Marián, and Marek Fraštia. "Photogrammetric Measurement of a Wooden Truss." Slovak Journal of Civil Engineering 26, no. 4 (December 1, 2018): 1–10. http://dx.doi.org/10.2478/sjce-2018-0022.
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Abstract Wooden trusses are a very specific object for measurement. They are often very complex and hard to reach; they are characterized by narrow spaces and low-lighting conditions. In recent years, laser scanning technology was mostly used for this task, because of its contactless nature, the possibility of measurement in the dark, and the robustness of the resulting 3D point clouds. Photogrammetry was mostly used in special cases, e.g., for the measurement of a few selected truss components, but not for the 3D modelling of an entire truss. However, the progress in computer vision algorithms is allowing us to accomplish image-based-modelling on very complex objects. The following contribution compares the point clouds of a wooden truss generated by the leading photogrammetry systems with a point cloud from laser scanning. The results confirm the interesting potential of actual photogrammetric methods in the modelling of complex objects such as wooden trusses.
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Bonopera, Marco, Kuo-Chun Chang, Chun-Chung Chen, Tzu-Kang Lin, and Nerio Tullini. "Bending tests for the structural safety assessment of space truss members." International Journal of Space Structures 33, no. 3-4 (September 2018): 138–49. http://dx.doi.org/10.1177/0266351118804123.
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This article compares two nondestructive static methods used for the axial load assessment in prismatic beam-columns of space trusses. Examples include the struts and ties or the tension chords and diagonal braces of steel pipe racks or roof trusses. The first method requires knowledge of the beam-column’s flexural rigidity under investigation, whereas the second requires knowledge of the corresponding Euler buckling load. In both procedures, short-term flexural displacements must be measured at the given cross sections along the beam-column under examination and subjected to an additional transverse load. The proposed methods were verified by numerical and laboratory tests on beams of a small-scale space truss prototype made from aluminum alloy and rigid connections. In general, if the higher second-order effects are induced during testing and the corresponding total displacements are accurately measured, it would be easy to obtain tensile and compressive force estimations.
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Aslanova, Fidan. "A Comparative Study of the Hardness and Force Analysis Methods Used in Truss Optimization with Metaheuristic Algorithms and Under Dynamic Loading." Journal of Research in Science, Engineering and Technology 8, no. 1 (September 29, 2020): 25–33. http://dx.doi.org/10.24200/jrset.vol8iss1pp25-33.
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Increasing the scarcity of raw materials, and the tendency to have light, efficient and inexpensive structures demonstrates the importance of structural optimization. In the optimization process, truss structures are of particular interest due to their high performance in the construction of a variety of structures. The conducted research in this area has produced a great variety of optimization methods, and the researchers emphasize the effectiveness of their proposed method. Considering this issue, summarize and perform a comparative study between optimization methods (classical methods and Metaheuristic Algorithms), analysis methods used in optimization (hardness and force methods) and different optimization loads (static and dynamic loads) is needed to choose the right method and use them more effectively. By examining the research that has been done, it can be noted that the optimizations mentioned above should be compared from many perspectives. In this paper, a decision was made to make a general comparison of the analysis methods used to trusses optimization to provide the basis for further comparisons. In the present study, 19 articles (from 2003 to 2017) have been studied and compared using Metaheuristic algorithms and under dynamic loading in order to compare two methods (hardness and force methods) of analysis in the field of optimization of trusses in terms of optimization types, target function types, constraints and plane and space truss types, and Large-scale trusses, and finally, these two analysis methods were further scrutinized to optimize the 10-member truss plane. The results of this research can be a useful aid for optimization researchers to identify the gaps and deficiencies of truss optimization research.
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Kok, Ka Yee, Hieng Ho Lau, Thanh Duoc Phan, and TIina Chui Huon Ting. "Design optimisation for cold-formed steel residential roof truss using genetic algorithm." World Journal of Engineering 15, no. 5 (October 1, 2018): 575–83. http://dx.doi.org/10.1108/wje-10-2017-0322.
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Purpose This paper aims to present the design optimisation using genetic algorithm (GA) to achieve the highest strength to weight (S/W) ratio, for cold-formed steel residential roof truss. Design/methodology/approach The GA developed in this research simultaneously optimises roof pitch, truss configurations, joint coordinates and applied loading of typical dual-pitched symmetrical residential roof truss. The residential roof truss was considered with incremental uniform distributed loading, in both gravitational and uplift directions. The structural analyses of trusses were executed in this GA using finite element toolbox. The ultimate strength and serviceability of trusses were checked through the design formulation implemented in GA, according to the Australian standard, AS/NZS 4600 Cold-formed Steel Structures. Findings An optimum double-Fink roof truss which possess highest S/W ratio using GA was determined, with optimum roof pitch of 15°. The optimised roof truss is suitable for industrial application with its higher S/W ratio and cost-effectiveness. The combined methodology of multi-level optimisation and simultaneous optimisation developed in this research could determine optimum roof truss with consistent S/W ratio, although with huge GA search space. Research limitations/implications The sizing of roof truss member is not optimised in this paper. Only single type of cold-formed steel section is used throughout the whole optimisation. The design of truss connection is not considered in this paper. The corresponding connection costs are not included in the proposed optimisation. Practical implications The optimum roof truss presented in this paper is suitable for industrial application with higher S/W ratio and lower cost, in either gravitational or uplift loading configurations. Originality/value This research demonstrates the approaches in combining multi-level optimisation and simultaneous optimisation to handle large number of variables and hence executed an efficient design optimisation. The GA designed in this research determines the optimum residential roof truss with highest S/W ratio, instead of lightest truss weight in previous studies.
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Hou, Shu Li, Xiao Dong Yang, and Ming Dong Wang. "Design of a Steel Pipe Truss for a Hot Spring Spa." Applied Mechanics and Materials 351-352 (August 2013): 195–98. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.195.
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Based on a real project, this paper presents the design of a space steel pipe truss with a triangular cross section upside down, in which it covers the selection of structure type, arrangement of the structure, loads and load combination, structural analysis as well as the detailing of some major joints. Thus it can serve as a reference for the design of similar large-span trusses.
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Clarke, Cory, and Phillip Anzalone. "Trusset: Parallel Development of Software and Construction Systems for Space-Truss Structures." International Journal of Architectural Computing 2, no. 2 (June 2004): 229–44. http://dx.doi.org/10.1260/1478077041518700.
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Tyburec, Marek, and Jan Zeman. "Comparison of Semidefinite Solvers for Topology Optimization of Cantilever Trusses Subject to Fundamental Eigenvalue Constraint." Advanced Materials Research 1144 (March 2017): 172–77. http://dx.doi.org/10.4028/www.scientific.net/amr.1144.172.
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Optimal design of trusses is a widely developed field of structural optimization. In topology optimization the infinite design space is usually discretized into a finite ground structure defining the set of all feasible joints and bars. In this paper we adopt semidefinite programming (SDP) formulation of the topology optimization that enables us to obtain a globally optimal least compliant truss subjected to the constraints on structural volume and on the fundamental eigenvalue of free vibrations. For a model problem of 3D cantilever truss, we present a comparison of six solvers, namely CSDP, MOSEK, PENLAB, SDPA, SDPT3 and SeDuMi, from which it follows, that SDPA delivers the best computational performance.
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Ponechal, Radoslav, Peter Krušinský, Peter Pisca, and Renáta Korenková. "Simulation and measurement of microclimate in roof space on a gothic truss construction." MATEC Web of Conferences 196 (2018): 02044. http://dx.doi.org/10.1051/matecconf/201819602044.
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Research in the field of historical trusses has long been performed at the workplace of the authors. In each truss, there was recorded the general technical state and some even monitoring and analysing microclimate with the aim of specifying environmental conditions that would be suitable for preservation of a historical structure. The article shows the results of temperature and relative humidity measurement in roof space of the Roman-Catholic church in the historical centre of the village of Bela-Dulice as well as result of thermodynamic simulation of this space. The selected measurement was compared to the simulation results.
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Sastare, Ms Sayali. "Seismic Behaviour of Steel Staggered Truss in Building." International Journal for Research in Applied Science and Engineering Technology 9, no. VI (July 15, 2021): 725–31. http://dx.doi.org/10.22214/ijraset.2021.36450.
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In this study staggered-truss system (STS) is studied for structural steel framing for the multi-story and high-rise buildings. The staggered-truss systems (STS) consists of a series of story-high trusses spanning the total width between two rows of external columns and arranged in a staggered pattern on adjacent column lines. The system is known to be appropriate for use in residential buildings such as apartments, dormitory and hotels. The columns are located only on the external faces of the building. The large clear span and open areas can be created. The interaction of the floors, trusses, and columns makes the structure perform as a single unit, there by taking maximum advantage of the strength and rigidity of all the components simultaneously. Each component performs its particular function, totally dependent upon the others for its performance. These column free areas can be utilized for ballrooms, concourses and other large areas. The one added benefit of the staggered-truss framing system is that it is highly efficient for resistance to the lateral loading caused by wind and earthquake. The stiffness of the STS provides the desired drift control for wind and earthquake loadings. The staggered-truss framing system is one of the quickest available methods to use during winter construction. The floor system not only carries the direct vertical loads. In addition, It has to act as a diaphragm to transfer the horizontal shear forces between stories through truss diagonals. Because of this double use concept this system results in a lighter structure and provides more column-free space than a conventional beam-column framed structure.
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Yadollahi, Mehrzad Mohabbi, Fatma Karagöl, Mehmet Akif Kaygusuz, Rıza Polat, and Ramazan Demirboga. "Safety factor determining for space trusses by non-linear analysis and artificial neural network method." Science and Engineering of Composite Materials 20, no. 3 (August 1, 2013): 277–84. http://dx.doi.org/10.1515/secm-2012-0114.
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AbstractDetermining a feasible safety factor for space trusses is an important phase in structural analysis that could have economic benefits. We know there are many kinds of imperfections in structural elements, which include both material and geometric flaws. Predicting factual behavior of structures is very difficult and occasionally impossible. Elements with initial geometric imperfections in space trusses are a common phenomenon, in addition, equivalent initial geometric imperfections can be applied for modeling of residual stresses or eccentric loading effect. The number of members in the space structures is usually high as is the diversity in the kind of initial imperfection. Therefore, there is a high likelihood that models must be analyzed. The structure must be analyzed with non-linear methods, making these approaches time consuming, and potentially uneconomical. In this study, we selected 30 cases for random analysis based on Monte Carlo methods to find the bearing capacity of the space truss. We attained results from the LUSAS program LUSAS Modeller, Version 13, UK program and these were then exported as input data to the Artificial Neural Network (ANN) program. A reasonable neural network has been found of predicting another 30 cases for load bearing capacity without any analysis and only based on the neural network program. Finally, a new approach for determining the load capacity of the space trusses was extracted and we predicted the occurrence possibility of the convenience load bearing capacity in 60 cases.
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Dai, Ye, Zhaoxu Liu, Yunshan Qi, Hanbo Zhang, Bindi You, and Yufei Gao. "Spatial cellular robot in orbital truss collision-free path planning." Mechanical Sciences 11, no. 2 (July 6, 2020): 233–50. http://dx.doi.org/10.5194/ms-11-233-2020.
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Abstract. Aiming at the problem of moving path planning of a cellular robot on trusses in space station, a triangular prism truss is taken as the research object, and an optimized ant colony algorithm incorporating a gravitational search algorithm is proposed. The innovative use of the hierarchical search strategy which limits the exploration area, the use of gravity search algorithm to get the optimal solution of truss nodes, and further transform it into the initial value of pheromone in ant colony algorithm, can effectively prevent the algorithm from falling into the local optimal solution in the early stage, and make the optimization algorithm have a faster convergence speed. This paper proposes a heuristic function including the angle between the targets, which can effectively avoid blind search in the early stage and improve the ability of path search. The simulation results show that the path and planning time of the cellular robot can be effectively reduced when choosing truss path.
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Gong, Liang. "The Structural Design of a Cantilevered Roof System of a Stadium Stand." Applied Mechanics and Materials 94-96 (September 2011): 860–67. http://dx.doi.org/10.4028/www.scientific.net/amm.94-96.860.
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In this paper a simple statically determinate and indeterminate truss structure is chosen as the model for the design of the stadium stand. The design simplifies the canopy structure, considering actual handling of the connection of nodes; fewer nodes would be chosen for the convenience of installation. The supporting frame is put slantwise between the roof and vertical walls to improve the safety and reliability of the cantilevered structure. The roof truss adopts bidirectional and orthogonal divisions, adding up inclined trusses in divisions of upper and lower surfaces, thus increasing space stiffness. Schematic drawings, internal forces and material processing lists are put forward in this paper, aiming at less material, simple construction, saving manual labor and financial resources and satisfying the masses on the basis of enough intensity and stiffness.
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Chen, J. T., Y. L. Chang, S. Y. Leu, and J. W. Lee. "Static Analysis of the Free-Free Trusses by Using a Self-Regularization Approach." Journal of Mechanics 34, no. 4 (March 29, 2017): 505–18. http://dx.doi.org/10.1017/jmech.2017.15.
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AbstractFollowing the success of static analysis of free-free 2-D plane trusses by using a self-regularization approach uniquely, we further extend the technique to deal with 3-D problems of space trusses. The inherent singular stiffness of a free-free structure is expanded to a bordered matrix by adding r singular vectors corresponding to zero singular values, where r is the nullity of the singular stiffness matrix. Besides, r constraints are accompanied to result in a nonsingular matrix. Only the pure particular solution with nontrivial strain is then obtained but without the homogeneous solution of no deformation. To link with the Fredholm alternative theorem, the slack variables with zero values indicate the infinite solutions while those with nonzero values imply the case of no solutions. A simple space truss is used to demonstrate the validity of the proposed model. An alternative way of reasonable support system to result in a nonsingular stiffness matrix is also addressed. In addition, the finite-element commercial code ABAQUS is also implemented to check the results.
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Devert, Alexandre, Thomas Weise, and Ke Tang. "A Study on Scalable Representations for Evolutionary Optimization of Ground Structures." Evolutionary Computation 20, no. 3 (September 2012): 453–72. http://dx.doi.org/10.1162/evco_a_00054.
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This paper presents a comparative study of two indirect solution representations, a generative and an ontogenic one, on a set of well-known 2D truss design problems. The generative representation encodes the parameters of a trusses design as a mapping from a 2D space. The ontogenic representation encodes truss design parameters as a local truss transformation iterated several times, starting from a trivial initial truss. Both representations are tested with a naive evolution strategy based optimization scheme, as well as the state of the art HyperNEAT approach. We focus both on the best objective value obtained and the computational cost to reach a given level of optimality. The study shows that the two solution representations behave very differently. For experimental settings with equal complexity, with the same optimization scheme and settings, the generative representation provides results which are far from optimal, whereas the ontogenic representation delivers near-optimal solutions. The ontogenic representation is also much less computationally expensive than a direct representation until very close to the global optimum. The study questions the scalability of the generative representations, while the results for the ontogenic representation display much better scalability.
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Hollaway, L., and D. York. "Numerical Analyses of an Energy Loaded Joint for a Deployable Satellite Structure." International Journal of Space Structures 10, no. 1 (March 1995): 47–55. http://dx.doi.org/10.1177/026635119501000102.
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Reflectors which are an integral part of space vehicles must be collapsed into the body of the vehicle for transportation to space. It is not efficient to store solid reflectors with a diameter greater than about 2.5 m in the launch vehicle and consequently deployable reflectors are used. This paper discusses the use of a flexible joint mechanism to enable a large reflector to be folded to a compact size and then deployed at geosynchronous orbit. The joint would be incorporated into the members of a skeletal truss structure and their effect on the dynamic behaviour of a single structural member and a large truss framework has been studied. It has been shown that the resonant behaviour of a structural member was significantly altered by introducing a joint into the system, but that of large trusses was not as seriously affected and resembled the equivalent of a non-jointed structure. The resonant frequencies of the jointed structure are shown to be similar to those of the non-jointed one but the amplitudes of vibration are significantly lower.
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Wang, Dongwei, Mengfei Shang, and Panxu Sun. "Deformation Performance Analysis of a Truss Structure Based on the Deformation Decomposition Method." Buildings 12, no. 3 (February 23, 2022): 258. http://dx.doi.org/10.3390/buildings12030258.
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Trusses are among the basic components of large-span bridges and large-space structures. A method is proposed to conduct a comprehensive deformation analysis of a truss in terms of the basic rigid body displacements and the tension and compression deformation based on complete mathematical orthogonality and mechanical equilibrium. The correctness of the proposed method is verified by comparison with a traditional strain analysis. Furthermore, a relative deformation decomposition of the mode shape is proposed to analyse in detail its relative displacement and deformation. The correctness and superiority of the proposed method are verified by comparison with the modal mass participation coefficient method and the animation from observation method. Additionally, the relative deformation decomposition of a plane truss structure is realized under any load conditions based on the superposition of mode shapes. The quantitative analysis of the basic deformation performance of a plane truss structure can also be conducted by countable mode shapes, which do not involve load conditions. Finally, the number of mode shapes that must be considered differs when using the maximum displacement and the tension and compression deformation analysis indicators.
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Bekdaş, Gebrail, Melda Yucel, and Sinan Melih Nigdeli. "Evaluation of Metaheuristic-Based Methods for Optimization of Truss Structures via Various Algorithms and Lèvy Flight Modification." Buildings 11, no. 2 (January 31, 2021): 49. http://dx.doi.org/10.3390/buildings11020049.
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Truss structures are one of the major civil engineering members studied in the optimization research area. In this area, various optimization applications such as topology, size, cost, weight, material usage, etc., can be conducted for different truss structure types. In this scope with the present study, various optimization processes were carried out concerning two different large-scale space trusses to minimize the structural weight. According to this state, three structural models provided via two different truss structures, including 25 bar and 72 bar truss models, were handled for evaluation of six different metaheuristics together with the modification of Lèvy flight for three of the algorithms using swarm intelligence by considering both constant and variable populations, and different ranges for iterations, too. Additionally, the effects of the Lèvy flight function and whether it is successful or not in terms of the target of optimization were also investigated by comparing with some documented studies. In this regard, some statistical calculations were also realized to evaluate the optimization method performance and detection of optimum values for any data stably and successfully. According to the results, the Jaya algorithm can handle the optimization process successfully, including the case, without grouping truss members. The positive effect of Lèvy flight on swarm-based algorithms can be seen especially for the gray wolf algorithm.
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Lan, Tao, Ji Ping Hao, Si Yuan Zhao, and Xiao An Wang. "Study on Design Method of Mega-Structure Linked with the Ground." Advanced Materials Research 243-249 (May 2011): 1288–95. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.1288.
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Based on the research of Life Ring in Shen Fu, the basic criteria for structural design of the unconventional rigid mega-structure linked with the ground are proposed in this paper. Through the structure comparison and selection, the space steel truss is used as the optimal structure form. After static analysis and time-history analysis by FEM, it is found that the control load case is the combination of dead weight and wind load. Because of its long vibration period, the structure is not sensitive during an earthquake. The key design of the structure is the selection of foundation form, a mixed-foundation made of steel trusses with piles is proposed in this paper. The steel truss is used as a bridge which transmits forces between superstructure and foundation. At last, the pile foundation is classified by the loading mechanism, the analysis and design of key joints in the mixed-foundation is proposed.
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Miura, K. "Concepts of Deployable Space Structures." International Journal of Space Structures 8, no. 1-2 (April 1993): 3–16. http://dx.doi.org/10.1177/0266351193008001-202.
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This paper presents several concepts of deployable space structures with emphasis on their relation to the basic principles of mechanics on which the concepts depend. The following subjects are treated: the coilable longeron extendible mast and the theory of “Elastica” by Euler and Kirchhoff; the two-dimensionally deployable array and the theory of elastic surfaces (“Plate Elastica”) by Miura and Tanizawa; the variable geometry truss and the theory of truss by Mobius; the tension truss antenna and the theory of truss.
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Xiang, Kai, Guo Hui Wang, and Bi Zhao. "Fire Protection of Steel Space Truss Structures." Advanced Materials Research 671-674 (March 2013): 479–83. http://dx.doi.org/10.4028/www.scientific.net/amr.671-674.479.
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The fire protection method of steel space truss structures was researched. Fire protection methods of steel structures were listed. For steel space truss structures, the advantages and disadvantages of fire protection methods were introduced. The screen method was suitable for fire protection of steel space truss structures. One project of fire protection of steel space truss structure was shown as an example. The process of screen method was provided for fire protection of steel space truss structures. According to this project, the technology of fire protection of steel space truss structures was enriched. The research results could help to deal with fire protection of steel space truss structures.
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Farshi, B., and A. Alinia-ziazi. "Structural Synthesis by Method of Centers in Force Formulation under Size and Stress Constraints." Journal of Mechanics 26, no. 4 (December 2010): 513–24. http://dx.doi.org/10.1017/s1727719100004706.
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ABSTRACTThis paper studies a novel approach to optimize trusses and truss-like structures for minimum weight design. It is based on the force method of analysis which is incorporated inside the optimization routine. The design variables in force formulation are the member cross sectional areas and the redundant forces in each load condition. The optimization method used is the method of center points using the inscribed hyperspheres to the feasible-usable design space. By incorporating the analysis step as part of the optimization problem, a separate structural solution phase, which is necessary in all other methods, is avoided resulting in large computational savings. In this article the simplest form of structures i.e. trusses are treated to illustrate the efficacy of the method. Stress limits on the members as well as limitations on their sizes, and linking among them, under several load conditions have been considered. Combination of the method of center points and force formulation results in a viable routine for structural optimization. Comparison of the example results with those obtained by others clearly shows the effectiveness and novelty of the proposed method.
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Kirsanov, Mikhail N., and Oleg V. Vorobyev. "The analysis of dependence of the vibration frequency of a space cantilever truss on the number of panels." Vestnik MGSU, no. 5 (May 2021): 570–76. http://dx.doi.org/10.22227/1997-0935.2021.5.570-576.
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Introduction. The first (lowest) frequency of natural vibrations of a structure is one of its most important dynamic characteristics. Analytical solutions supplement numerical ones; they can be efficiently used to perform a rapid assessment of properties of structures, to analyze and optimize constructions and to test numerical results. A space cantilever truss consisting of three planar trusses with a rectangular grid is considered in the article. The objective is to find the analytical dependence between the frequency of natural vibrations of a structure and the number of panels. It is assumed that the truss mass is distributed among the joints. Only the vertical mass displacement is taken into account.
Materials and methods. Forces, arising in cantilever rods, are calculated by the Maple software as symbolic expressions, and the method of joint isolation is used here. The stiffness matrix is identified using the Mohr integral. Rods are assumed to be elastic, they have identical stiffness. The lower value of the vibration frequency is determined using the Dunkerley method. The final calculation formula used to identify the value of the vibration frequency is derived using the method of induction applied to a series of analytical solutions developed for trusses with a consistently increasing number of panels. When common members of sequences are found, genfunc operators of the Maple system are used. The analytical solution is compared with the numerical solution in terms of the first frequency using the analysis of the system spectrum featuring many degrees of freedom. The eigenvalues of the characteristic matrix are identified using the Eigenvalues operator from the Linear Algebra package.
Results. The comparison between the analytical values and the numerical solution shows that the Dunkerley method ensures the accuracy varying from 20 % for a small number of panels to 3 % if the number of panels exceeds ten. The size of the structure, the weight and stiffness of rods have little effect on the accuracy of the obtained values.
Conclusions. The lowest value obtained using the Dunkerley method in the form of a fairly compact formula has good accuracy, its application to a space structure with an arbitrary number of panels has a polynomial form equal to the number of panels, and it can be used in practical calculations.
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Wang, Dong-Wei, Li Ma, Xin-Tao Wang, and Ge Qi. "Sound transmission loss of sandwich plate with pyramidal truss cores." Journal of Sandwich Structures & Materials 22, no. 3 (February 26, 2018): 551–71. http://dx.doi.org/10.1177/1099636218759683.
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This paper presents the theoretical model of sandwich plate with pyramidal truss cores to investigate the acoustic property of transmission loss. The two-dimensional periodic model is established based on the assumption that the trusses are regarded as Euler-Bernoulli beams. The fluid-structure interaction is considered by imposing velocity continuity condition at fluid-structure interfaces. The periodic governing equations are derived by using space harmonic expansions and the principle of virtual work. Meanwhile, the practical specimens are fabricated by slitting and snap-fit assembly to conduct sound insulation experiment via standing wave tube method. The theoretical result shows satisfactory agreement with experimental data. The numerical discussions are conducted to demonstrate the effects of incident angles and topological parameters which should be helpful for practical design.