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This paper conducted a comprehensive study on the bearing capacity and damage behavior of circular high-strength concrete-filled thin-walled steel tubular (HCFTST) columns based on the quasi-static seismic test. The moment-axial force relationship was first analyzed in fiber element method, and the influences of key parameters including the peak strain of concrete, material strengths and diameter-to-thickness (D/t) ratios were investigated to develop a practical design method. Then, a dependent triaxiality fracture criterion of high-strength (HS) steel was introduced to establish the finite element damage model for revealing the seismic damage behavior of HCFTST columns, and subsequently a modified restoring force model based on the truss mechanism and the unified theory of concrete-filled steel tube was established and verified. The result indicates that: increasing the steel yield strength, reducing the concrete strength as well as the D/t ratio could respectively push the moment-axial force curves moving inward; the proposed parabolic moment-axial force curve agreed well with the tested bearing capacity; the HS steel tube generated a deep plasticity accumulation to induce the ductile fracture, and the concrete damage area appeared in a V-shaped distribution; increasing the axial compression ratios and D/t ratios amplified the fracture damage of the steel tube web; the established restoring force model displayed a comparatively reasonable accuracy on the degradation behavior (e.g., bearing capacity and stiffness) and the hysteretic characteristic (e.g. softening platform). The aforementioned study could provide the meaningful references for the design and seismic analysis of HCFTST columns.

The frequency constrained design of large-scale structures is a complex optimization problem with many local optima. In order to tackle this problem, in this paper, a chaotic version of a newly-established metaheuristic algorithm, the so-called Water Strider Algorithm (WSA), is introduced. This version repetitively diversifies solutions and then focuses on promising areas during the course of iterations. The chaotic algorithm involves two types of succession states, namely explorative and exploitative states, and it probabilistically switches between them using the Circle map with a quasi-cyclic behavior. To examine the effectiveness of this algorithm, it is applied to structural optimization of large-scale structures with multiple frequency constraints such as 600-, 1180- and 1410-bar dome trusses. The results show that the new version outperforms its basic version as well as some other well-established algorithms in the literature. The statistical measures reveal that it is reasonably capable of providing a satisfactory performance in terms of both obtaining lighter designs and convergence speed.

Natural structures are known to be the source of inspiration for numerous architectural and structural rules in the fields of aesthetics, function, and structure; therefore, the application of the principals governing them could be used for appropriate and optimal design. The present paper was conducted to model the natural structure of load transfer in order to design the structure of a pedestrian bridge with a span of 100 meters. This bridge is located in a mountain park in the tourist area of Kashan, 230 km south of Tehran. For this purpose, by examining the patterns in the nature, which provides a relevant answer to the problem, the spine of animals was identified as the bearing skeleton of the body, the best option for patterning. Inspired by it, a stable structure was designed as a skeleton of a bridge without a middle pillar. Based on a form inspired by the spine of a four-legged animal, the bridge structure was designed. To control the stability of the bridge structure against the loads, the initial design idea was analysed employing the Karamba plugin in Grasshopper software to identify its weaknesses and the final design was obtained. The final design was analysed with SAP2000 structural finite element software to ensure the stability and control of permissible deformations. Additionally, attention to the modular structure of the spine was the source of inspiration for the design of prefabricated elements of the bridge parts, which in addition to reducing the cost of execution, increases the speed of construction of the project. The final design of the pedestrian bridge, which acts similar to a suspension bridge in terms of load transfer and was inspired by the structure of a four-legged vertebrate, is a combination of truss and tensegrity structure and in addition to visual aesthetic, has optimal structural performance.

To ensure excellent performance of a micro reflective space camera, an integrated main supporting structure (IMSS) combined with a thin-walled tube and a supporting rod structure design is applied in this study. Firstly, this paper covers the design and comparison of the performance of three traditional types of main supporting structures (MSS), including thin-walled cylinder type, rod-supporting type and truss type. Then, an IMSS combined with a thin-walled tube and a supporting rod structure is described. In addition, a multi-objective integrated optimization method which allows automatic modeling, analysis, calculation and optimization is proposed. Further, the influence of the supporting rod angle on the structure performance is studied, the performance of stiffness, deformation and mass is better when the height ratio of the rod-structure and the thin-walled cylinder is 6:1. The IMSS mass is only 0.56 kilograms, that is 11.2 % of the total mass of the payload, and the maximum deformation on the supporting bar is no more than 4.5 nm. Finally, the IMSS performance is analyzed by the finite element method and experimental verification, and the first order frequency is up to 192.7 Hz. The degree of light weight is significantly better than that of the traditional structures. The results of the experiment further prove the stability of the IMSS.

A new type of composite structure, the composite box girder with corrugated steel webs (CSWs) and trusses, is proposed recently. In order to investigate the structural behavior under positive and negative bending moments, flexural tests of the continuous girder were carried out, and the failure modes, deformation patterns, strain distribution, and development of the concrete cracks were investigated. Finite element analysis was conducted to investigate the effect of the range of concrete in the steel tube and the thickness of CSWs on the flexural behavior. The experimental and numerical results show that the test beam has a good ductility and integrity under flexural load. The contribution of CSWs to the flexural bearing capacity is very small and can be neglected. Besides, the plane section assumption is still valid when only top concrete slab and bottom steel tubes are concerned. The concrete filled in bottom steel tubes increases the stiffness and the bearing capacity of the girder. Equations to calculate the flexural bearing capacity under positive and negative bending moments were put forward and then verified with experimental results.

PurposeThe purpose of this paper is to contribute to the solution of the buckling and resonance stability problems in inelastic beams and wooden plane trusses, taking into account geometric and material defects.Design/methodology/approachTwo sources of non-linearity are analyzed, namely the geometrical non-linearity due to geometrical imperfections and material non-linearity due to material defects. The load-bearing capacity is obtained by the rheological-dynamical analogy (RDA). The RDA inelastic theory is used in conjunction with the damage mechanics to analyze the softening behavior with the scalar damage variable for stiffness reduction. Based on the assumed damages in the wooden truss, the corresponding external masses are calculated in order to obtain the corresponding fundamental frequencies, which are compared with the measured ones.FindingsRDA theory uses rheology and dynamics to determine the structures' response, those results in the post-buckling branch can then be compared by fracture mechanics. The RDA method uses the measured P and S wave velocities, as well as fundamental frequencies to find material properties at the limit point. The verification examples confirmed that the RDA theory is more suitable than other non-linear theories, as those proved to be overly complex in terms of their application to the real structures with geometrical and material defects.Originality/valueThe paper presents a novel method of solving the buckling and resonance stability problems in inelastic beams and wooden plane trusses with initial defects. The method is efficient as it provides explanations highlighting that an inelastic beam made of ductile material can break in any stage from brittle to extremely ductile, depending on the value of initial imperfections. The characterization of the internal friction and structural damping via the damping ratio is original and effective.

Unsymmetrical complex plate and shell structure is one of the common engineering structures. In practice, more redundant materials exist because of the irrationality of this kind of structure with heavy load and multiple working conditions, and the study of its topology optimization has become an engaging topic. Using the SIMP model, topological results show that one side of the main web is a hollow structure, and the other side of the auxiliary web is a truss structure. According to the topological results and considering manufacturable processing, a new structure is redesigned, the size and shape of the redesigned structure is secondary optimized, and the final structure is obtained. The method in this paper not only meets the performance requirements of the unsymmetrical complex plate and shell structures, but also realizes the topology and lightweight. The effectiveness scientific research value of the proposed method is verified by engineering examples.

In this study, seismic fragility analysis of multi-span steel truss bridges still giving service in railway network of Turkey was aimed. For this purpose, two representative multi-span steel truss bridges were selected in Turkish railway lines. A detailed three-dimensional inelastic finite element (FE) model for each bridge was created using commercial FE software. These models were used to perform non-linear time history analyses for each of the selected 30 ground motions scaled to 10 different peak ground acceleration (PGA) values to assess seismic demands of the bridges. To develop fragility curves, probabilistic seismic demand models (PSDMs) were defined. The most appropriate ground motion intensity measure (IM) for PSDMs of both bridges was determined among 11 IMs and the PGA was found as the optimal IM. Finally, the fragility curves for both the components and structural systems of the bridges were developed. The results clearly showed that the multi-span continuous (MSC) steel truss bridge is more vulnerable than the multi-span simply supported (MSSS) steel truss bridge, and for both bridge types, steel bearings are the most vulnerable components. Additionally, top wind braces for the MSC bridge as well as transverse beams and truss vertical members for the MSSS bridge were found as the most vulnerable superstructure members.

Optimization methodologies are being utilized in various structural designing practices to solve size, shape and topology optimization problems. A heuristic Particle swarm optimization (HPSO) algorithm was anticipated in this article in order to address the size optimization problem of truss with stress and displacement constraints. This article contributes in improvisation in the truss structure design rationality while reducing the engineering cost by proposing the HPSO approach. Primarily, the basic principle of the original PSO algorithm is presented, then the compression factor is established to improve the PSO algorithm, and a reasonable parameter setting value is presented. To validate the performance of the proposed optimization approach, various experimental illustrations were performed. The results show that the convergence history of experimental illustration 2 and experimental illustration 3 is optimal. The experimental illustration 2 converges after about 150 iterations, however, the experimental illustration 3 is close to the optimal solution after about 500 iterations. Therefore, the PSO algorithm can successfully optimize the size design of truss structures, and the algorithm is also time efficient. The improved PSO algorithm has good convergence and stability, and can effectively optimize the size design of truss structures.

This article investigates the use of Harris Hawks Optimization (HHO) to solve planar and spatial trusses with design variables that are discrete. The original HHO has been used to solve continuous design variables problems. However, HHO is formulated to solve optimization problems with discrete variables in this research. HHO is a population-based metaheuristic algorithm that simulates the chasing style and the collaborative behavior of predatory birds Harris hawks. The mathematical model of HHO uses a straightforward formulation and does not require tuning of algorithmic parameters and it is a robust algorithm in exploitation. The performance of HHO is evaluated using five benchmark structural problems and the final designs are compared with ten state-of-the-art algorithms. The statistical outcomes (average and standard deviation of final designs) show that HHO is quite consistent and robust in solving truss structure optimization problems. This is an important characteristic that leads to better confidence in the final solution from a single run of the algorithm for an optimization problem.

Taking roadway along gob with narrow coal pillar in fully mechanized top coal caving face for extra thick coal seam as the research object, this paper systematically studies two key problems of asymmetric failure mechanism and control technology of gob side entry driving in extra thick coal seam by using comprehensive research methods such as theoretical analysis, numerical simulation and field measurement. Firstly, by establishing the mechanical model of overlying strata of gob side entry in fully mechanized top coal caving face of extra thick coal seam, the mechanical source of roof asymmetric failure of gob side entry is obtained. Secondly, the deflection stress invariant is selected to analyze the temporal and spatial evolution law of surrounding rock deformation and failure in the whole process of mining. Finally, the concept of asymmetric control and support technology of gob side entry in fully mechanized top coal caving face of extra thick coal seam are proposed, and the field engineering test is carried out. The research results show that: during the mining of extra thick coal seam, the overlying strata of gob side entry form a composite structure of “low cantilever beam + high hinged rock beam”, and the subsidence and rotation of cantilever beam is the fundamental reason for the roof asymmetric settlement and two sides asymmetric failure of gob side entry. During the mining, the bearing capacity of the narrow coal pillar and the roadway near the narrow coal pillar decreases, and the storage capacity of the distortion energy also further decreases, forcing the deviator stress to transfer to the deep part of the solid coal wall, resulting in more significant asymmetric deformation and failure on both sides of the roadway with the center line as the axis; The asymmetric control concept with asymmetric anchor cable truss and anchor cable channel steel composite structure as the core is constructed, and the supporting scheme of “anchor cable channel steel composite structure + asymmetric anchor cable truss structure + high strength anchor cable structure at the side” is put forward, and the field application effect is remarkable.

To study the design method of openings on the web of an I-beam, three I-beams with different circular holes were designed using the traditional truss mechanism, and the circular holes were reinforc...

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.

Variable neighborhood search (VNS) is a metaheuristic approach for solving combinatorial and global optimization problems in discrete search space. This paper explores the possibility of applying VNS and its several extensions to the optimization of truss structures considering the cross sections of the members as discrete variables. The constraints imposed to the optimization are the allowable stress and the displacement limits on nodes. Various truss structure examples with fixed geometries are presented in order to demonstrate the effectiveness of the VNS and its extensions compared with other methods.

It is well known that the vertical vibrations of lightweight timber floors would cause discomfort to the occupants. As a new kind of flooring system, the metal-plate-connected timber truss joist floors were developed due to their larger spans and easier crossing of pipes and cables after sawn timber and I-joist floors. In this paper, the vibration modes and transfer functions of sixteen metal-plate-connected timber truss joist floors over a nominal span of 6 m were determined experimentally to measure the changes in vibration frequencies and transmissions obtained after the installation of strongbacks and strappings. The results showed that the fundamental natural frequencies of the metal-plate-connected timber truss joist floors at a 400 mm joist spacing were about 15 Hz, while the frequencies of the floors at a 600 mm joist spacing were about 12.5 Hz. The bracing elements of the strongbacks and strappings mainly enhanced the system stiffness in the across-joist direction of the flooring system, but they did not govern the fundamental natural frequencies of the floors and just changed the spacing of adjacent natural frequencies. The bracing elements as secondary elements of the floors also altered the vibration transmission paths in the across-joist direction. The frequencies where the stronger vibration transfers happened in the direction perpendicular to floor joists were generally above 15 Hz. Proper installation measurements of bracing elements in practical control need to be taken to alleviate the vibration response intensity at the targeted locations and frequencies.

The present paper deals with structural health monitoring of trusses, space frame and plate structure utilizing the Bayesian data fusion approach. The application of the proposed approach has been demonstrated on a 25-member plane truss, a 42-member space frame, a cantilever plate and a 120-member space truss. Different damage indexes of interest have been calculated for the damaged structure utilizing the natural frequency and modeshapes as damage indicators. Damage indexes used are modal strain energy (DIMSE), frequency response function strain energy dissipation ratio (FRFSEDR), flexibility strain energy damage ratio (FSEDR) and residual force-based damage index (RFBDI). Next, the Bayesian data fusion approach has been applied to these four damage indexes to find out the accurate damage location. The proposed approach reduces the number of suspected damaged elements in the structure significantly, thus reducing the computational time of optimization algorithm. Proposed algorithm has also shown encouraging performance in noisy environments. Overall present approach is found to be robust and computationally efficient, and thus can be applied for damage detection involving field evaluation of various structures.

The concept of ‘structural connectivity’ is introduced to assess the connectivity of structural trusses and road networks, which are examples of two-dimensional assemblies. Metrics for such connect...

This paper describes a study on improving redundancy in a 240 m span steel Pratt truss bridge. Redundancy was evaluated from two perspectives. The first perspective was how many members would induce bridge collapse owing to their own damage, and the second perspective was how many members would be damaged owing to another member’s damage. Members corresponding to these two perspectives were widely present throughout the subject truss bridge. As a measure to improve redundancy of the subject truss bridge, the method of installing alternative load paths by retrofitting additional braces was studied. Three proposals with different geometry of the additional braces were compared, and "X bracing", which equipped X-shaped braces by adding braces in the opposite direction to the existing diagonal member, demonstrated excellent performance. In addition, the effect of the method retrofitting the cable along the member was also studied. Next, the placement patterns of "X bracing" on 18 truss panels of the subject truss bridge were examined using an optimization technique. It was clarified that examination of the placement for the additional braces was important for the efficient improvement of redundancy, and that the optimum placement of X bracing was in the alternating areas. Finally, the buckling gusset plate of the I-35 W bridge was also in the alternating area, suggesting that reinforcement of the alternating area might be important for redundancy of truss bridges.

This paper gives a new formulation to design adaptive structures through total energy optimization (TEO). This methodology enables the design of truss as well as tensegrity configurations that are equipped with linear actuators to counteract the effect of loading through active control. The design criterion is whole-life energy minimization which comprises an embodied part in the material and an operational part for structural adaptation during service. The embodied energy is minimized through simultaneous optimization of element sizing and actuator placement, which is formulated as a mixed-integer nonlinear programming problem. Optimization variables include element cross-sectional areas, actuator positions, element forces, and node displacements. For tensegrity configurations, the actuators are not only employed to counteract the effect of loading but also to apply appropriate prestress which is included in the optimization variables. Actuator commands during service are obtained through minimization of the operational energy that is required to control the state of the structure within required limits, which is formulated as a nonlinear programming problem. Embodied and operational energy minimization problems are nested within a univariate optimization process that minimizes the structure’s whole-life energy (embodied + operational). TEO has been applied to design a roof and a high-rise adaptive tensegrity structure. The adaptive tensegrity solutions are benchmarked with equivalent passive tensegrity as well as adaptive truss solutions, which are also designed through TEO. Results have shown that since cables can be kept in tension through active control, adaptive tensegrity structures require low prestress, which in turn reduces mass, embodied energy, and construction costs compared to passive tensegrity structures. However, while adaptive truss solutions achieve significant mass and energy savings compared to passive solutions, adaptive tensegrity solutions are not efficient configurations in whole-life energy cost terms. Since cable elements must be kept in tension, significant operational energy is required to maintain stable equilibrium for adaptation to loading. Generally, adaptive tensegrity solutions are not as efficient as their equivalent adaptive truss configurations in mass and energy cost terms.

In trusses, deck type and through type truss systems are generally provided with various member arrangements. To utilize the materials used in the trusses more efficiently, RCC decks are nowadays made composite with the truss members. In this paper, analysis of 72.0 m deck type and through type, non-composite and composite bridges is presented. The bridges are modelled using STAAD. Pro v8i software with truss members as beam element and deck slab modelled as four noded plate element. The loading on the bridge is done as per the provisions of IRC-6 and IRC-24. The composite deck effectively reduces the horizontal deflections due to lateral seismic and wind loads in both the truss systems. Decrement in vertical deflection of the truss system was also observed making the structure mode stiffer. Stresses in the members made composite with the deck slab were also reduced and hence resulted in material saving and decreased steel offtake. In the case of composite deck type bridges due to load sharing by the deck slab, the stresses in the top chord are reduced significantly hence eliminating the chances of buckling. Advantages of composite deck are better utilized in deck type bridge system compared to through type bridge system.

Introduction: Interbody fusion devices are customarily used in fusion of the anterior spinal column for treatment of degenerative disc disease. Their traditional role is to reestablish and maintain intervertebral disc height, contain bone graft and provide mechanical support for the spine while osseointegration takes place. Utilizing the principles of mechanobiology, a unique biokinetic interbody fusion device has been developed that employs an advanced structural design to facilitate and actively participate in the fusion consolidation process.Areas covered: This article profiles and characterizes 4WEB Medical's Truss Implant Technology™ which includes a range of 3D-printed titanium spinal interbody implants and non-spinal implants whose design is based on truss structures enabled by advances in additive manufacturing. Four main areas of the implant design and functionality are detailed: bio-architecture, mechanobiologic underpinnings, bioactive surface features, and subsidence resistance. Pre-clinical and clinical examples are provided to describe and specify the bioactive roles and contributions of each design feature.Expert opinion: The distinct and unique combination of features incorporated within the truss cage design results in a biokinetic implant that actively participates in the bone healing cascade and fusion process.

Приводится анализ частоты собственных колебаний большепролетной фермы с фланцевыми соединениями. Выполнен расчет фланцевого соединения с различными случаями исключения болтов из работы соединения. Анализ результата расчета показал, что возникновение повреждений и дефектов конструкций здания в локальных зонах, величина которых несущественно снижает общую жесткость каркаса, практически не влияет на динамические характеристики каркаса. The analysis of the natural vibration frequency of a large-span truss with flanged connections is given. The calculation of the flange connection with various cases of exclusion of bolts from the connection operation is performed. Analysis of the calculation results showed that the occurrence of damage and defects in the building structures in local areas, the value of which significantly reduces the overall rigidity of the frame, practically does not affect the dynamic characteristics of the frame.

This study aims to develop an advanced integral terminal sliding-mode robust control method using a disturbance observer (DO) to suppress the forced vibration of a large space intelligent truss structure (LSITS). First, the dynamics of the electromechanical coupling of the piezoelectric stack actuator and the LSITS, based on finite element and Lagrangian methods, are established. Subsequently, to constrict the vibration of the structure, a novel integral terminal sliding-mode control (ITSMC) law for the DO is used to estimate the parameter perturbation of the LSITS based on a continuous external disturbance. Simulation results show that, under a forced vibration and compared with the ITSMC system without a DO, the displacement amplitude of the ITSMC system with the DO is effectively reduced. In the case where the model parameters of the LSITS deviate by ±50%, and an unknown continuous external disturbance exists, the control system with the DO can adequately attenuate the structural vibration and realize robust control. Concurrently, the voltage of the employed piezoelectric stack actuator is reduced, and voltage jitter is alleviated.

International audience; The present work addresses the problem of maximizing a structure load-bearing capacity subject to given material strength properties and a material volume constraint. This problem can be viewed as an extension to limit analysis problems which consist in finding the maximum load capacity for a fixed geometry. We show that it is also closely linked to the problem of minimizing the total volume under the constraint of carrying a fixed loading. Formulating these topology optimization problems using a continuous field representing a fictitious material density yields convex optimization problems which can be solved efficiently using stateof-the-art solvers used for limit analysis problems. We further analyze these problems by discussing the choice of the material strength criterion, especially when considering materials with asymmetric tensile/compressive strengths. In particular, we advocate the use of a L 1-Rankine criterion which tends to promote uniaxial stress fields as in truss-like structures. We show that the considered problem is equivalent to a constrained Michell truss problem. Finally, following the idea of the SIMP method, the obtained continuous topology is post-processed by an iterative procedure penalizing intermediate densities. Benchmark examples are first considered to illustrate the method overall efficiency while final examples focus more particularly on no-tension materials, illustrating how the method is able to reproduce known structural patterns of masonry-like structures. This paper is accompanied by a Python package based on the FEniCS finite-element software library.

Purpose This study aims to include the diagnosis of an old concrete deck steel truss rural road bridge in the damaged and retrofitted state through vibration response signals. Design/methodology/approach The analysis of the vibration response signals is performed in time and time-frequency domains using statistical features-root mean square, impulse factor, crest factor, kurtosis, peak2peak and Stockwell transform. The proposed methodology uses the Hilbert transform in combination with spectral kurtosis and bandpass filtering technique for obtaining robust outcomes of modal frequencies. Findings The absence or low amplitude of considered mode shape frequencies is observed both before and after retrofitting of bridge indicates the deficient nodes. The kurtosis feature among all statistical approaches is able to reflect significant variation in the amplitude of different nodes of the bridge. The Stockwell transform showed better resolution of present modal frequencies but due to the yield of additional frequency peaks in the vicinity of the first three analytical modal frequencies no decisive conclusions are achieved. The methodology shows promising outcomes in eliminating noise and visualizing distinct modal frequencies of a steel truss bridge. Social implications The findings of the present study help in analyzing noisy vibration signals obtained from various structures (civil or mechanical) and determine vulnerable locations of the structure using mode shape frequencies. Originality/value The literature review gave an insight into few experimental investigations related to the combined application of Hilbert transform with spectral kurtosis and bandpass filtering technique in determining mode frequencies of a steel truss bridge.

Este artigo desenvolve uma metodologia numérica, utilizando conjuntamente as plataformas computacionais ANSYS® e Matlab®, para localizar e quantificar danos estruturais em treliças e vigas. Esses sistemas estruturais são modelados numericamente via Método dos Elementos Finitos no ANSYS®, e posteriormente, o sinal (deflexão) sofrida pela estrutura é transformado pela Transformada Contínua de Wavelet (TW) no Matlab®. A modelagem da treliça emprega um elemento linear com dois nós e dois graus de liberdade de translação por nó, enquanto as vigas empregam um elemento quadrilateral com quatro nós e dois graus de liberdade por nó. A modelagem das vigas empregam o conceito de estado plano de tensões. Várias wavelets mães e disponíveis na plataforma numérica do Matlab® são utilizadas para localizar o dano do tipo perda de rigidez estrutural, por meio da criação de entalhes nas vigas ou por meio da redução no módulo de Young do material das barras da treliça. Índices de dano são utilizados para quantificar esses mecanismos de dano. Para a detecção do dano na treliça é necessário conhecer os sinais da estrutura sã e danificada. Já no caso das vigas, somente o sinal na condição danificada é necessário. As wavelets-mães: Daubechies, Symlets, Coiflets, BiorSplines e ReverseBior conseguiram captar o dano implementado na treliça, enquanto as de Meyer e de Haar não foram eficientes nesta tarefa. Nas vigas todas as wavelets-mães conseguiram captar o dano, com maior ou menor precisão, sendo as mais eficientes dentre elas a Daubechies, Biorthogonal e Riorthogonal. Além disso, as duas wavelets mães Biorthogonal e RBiorthogonal apresentaram a mesma capacidade de detecção do dano nas simulações realizadas.

With the increase of the arch bridge span, the mechanical properties of arch bridges will decrease rapidly. In order to solve this problem, triangular net is set between the arch rib and girder to form a kind of truss arch bridge in which arch rib acts as top chord, girder acts as lower chord, triangular net acts as web member, and hangers provide elastic restrains at several points. The triangle stability of the truss can improve linear stiffness of arch rib and girder, which will thus improve the mechanical properties of arch bridges. A test bridge with a span of 50 m was built to prove the superiority of the truss arch bridge with multi-point elastic constraints (MTAB). Structural stresses and displacements were obtained through dead load experiments, and the mechanical properties of the structure were calculated through the finite element (FE) software. It is turned out that, compared with the conventional through arch bridge (CTAB), the mechanical performance of the MTAB is greatly improved. The test values of structural stresses and displacements match calculation values well. Moreover, with the same steel consumption, the more layers of the triangular net, the better the mechanical properties of the structure.

The article is devoted to the calculated regulation of the stress deformation state (SDS) of combined steel trusses, which allows to reduce the efforts in some sections of the structure by increasing the efforts in other and design evenly stressed structures as the most rational systems. It is shown that the calculated method of SDS regulation makes it possible to reduce steel consumption by up to 34%. Four methods of calculated SDS regulation are proposed. The advantages of combined structures are given: the concentration of materials and the possibility of designing them as low-element. As shown in the example, for the quantitative criterion of quality it is possible to use rationally the maximum potential energy of deformation. Dependences for calculation of the maximum potential energy of compressed stretched, and compressed-bent elements of rod-bearing steel structures are given.

In this paper a research work done to optimize the truss structure using modified ABC algorithm. Three test problem were conducted to verify that the modified ABC algorithm is effective in optimizing. MATLAB software used in this work. The result obtained by modified ABC algorithm is compared with other optimization method. The result shows that modified ABC algorithm gives result as good as other methods.

Even through the topology optimal truss-like structure based on the truss-like material model is very close to its analytical solution, further post-processing is required to form a truss or a homogeneous isotropic perforated plate. In this paper, an optimal truss-like material distribution field is expressed by a B-spline function. For the convenience of processing, the optimal material distribution domain of a truss-like structures is firstly extended into a curved quadrilateral extension domain. Then, the relationship between the B-spline curve clusters and the distribution of truss-like material members is established by a sample points array. Combined with the distribution of materials, a topology structure that meets the design requirements is formed. Numerical examples with three models show that the B-spline function can describe the distribution field of truss-like material members efficiently, and the number of the truss-like material members can be actively controlled to meet different design needs. Comparison between the optimal results and them of the traditional analytical solution is made and results show that the topological structure is close to the analytical solution.

The population structure of Barbodes carnaticus species was studied using conventional (based on body morphometrics and meristic) and image-based analysis (truss network system) methods. The study was carried out with four stocks, namely Karnataka (KA) and Tamil Nadu (TN) stocks from the River Cauvery, Kerala (KE) stock from the River Chalakudy and farm-reared stock (CI) from Central Institute of Freshwater Aquaculture, Bangalore. A total of 27 morphometric, 9 meristic and 30 truss measurements were used in the study for the stock structure. Fifteen landmarks were used to generate 30 truss distance measurements. The principal component analysis (PCA), factor analysis (FA), discriminant function analysis (DFA) and cluster analysis (CA) were deployed to determine the variation using both the conventional and truss variables. Variations (86.9%) among the morphometric characters were explained by five principal components, while four principal components explain 96.01% of the variation among the truss distances. DFA using conventional method correctly classified 100% of the original grouped classes of the KA, KE and CI and 93.8% of TN stocks. The DFA employed with truss distance was classified into the stocks CI, KA, KE and TN, and the values are 100, 89.1, 8.6 and 6.1%, respectively. Factor analysis based on truss morphometry showed that factor one is related to body shape and factor two is related to head shape. Two clusters were identified in both the conventional and the truss distance analysis. Truss distance-based cluster showed that the KE and CI stocks are similar compared to the TN stock. In contrary, morphometry-based cluster showed the KE and TN stocks are similar compared to CI stock. The multivariate analysis showed that the farm-reared stock (CI) is different from the wild stocks (KA, KE and TN). This study explained that the combination of the conventional and image-based truss network analysis helps to discriminate various stocks of B. carnaticus. Based on the PCA, bilinear data models were generated using R 3.5.3 software for predicting the stock of each individual. Stock discrimination of this species was mainly due to the geographic isolation, river ecology and temperature variations. The stocks of B. carnaticus are highly exploited from the studied rivers, and the species is an important candidate for species diversification to enhance aquaculture production. Within stock variations are found to be minimum in the present morphometric study, hence the gene pool identification and marker study are required for better understanding of the stocks. This stock structure study may help to develop conservation programmes for this endemic species through a more scientific approach.

An enhanced symbiotic organisms search (ESOS) algorithm is developed and presented. Modifications to the basic symbiotic organisms search algorithm are carried out in all three phases of the algorithm with the aim of balancing the exploitation and exploration capabilities of the algorithm. To verify validity and capability of the ESOS algorithm in solving general optimization problems, the CEC2014 set of 22 benchmark functions is first optimized and the results are compared with other metaheuristic algorithms. The ESOS algorithm is then used to optimize the sizing and shape of five benchmark trusses with multiple frequency constraints. The best (minimum) mass, mean mass, standard deviation of the mass, total number of function evaluations, and the values of frequency constraints are then compared with those of a number of other metaheuristic solutions available in the literature. It is shown that the proposed ESOS algorithm is generally more efficient in optimizing the shape and sizing of trusses with dynamic frequency constraints compared to other reported metaheuristic algorithms, including the basic symbiotic organisms search and its other recently proposed improved variants such as the improved symbiotic organisms search algorithm (ISOS) and modified symbiotic organisms search algorithm (MSOS).

Conventional metallic sandwich panels are widely used for noise control owing to their good noise control capabilities and excellent mechanical strength-to-weight ratio property. Furthermore, sound-absorbing products consisting of glass or mineral fiber materials are generally filled into the sandwich structures to lower the vibration response in resonance frequency and to enhance the structural noise attenuation capacity. In the present study, a fiber-reinforced graphite material is used as an alternative to its metallic counterparts. Moreover, a wood-based renewable absorption material is used as the absorption material and is filled into the sandwich structural core. The vibro-acoustic characteristics of the panel with such a design are numerically investigated using Actran. The findings of the research indicate that the proposed sandwich structure achieves advanced low-frequency noise control performance in comparison with other conventional metallic sandwich panels. Approximately 7 dB increase in sound transmission loss in the audible-frequency range is achieved in addition to a reduced panel weight and more stable vibration with reduced amplitude. The existing data available in the literature are employed for validating and illustrating the accuracy and reliability of the proposed approach.

This paper presents an investigation of changes on design and material of a Howe bridge under vertical loads. Specifically, it aimed to find out how small changes on Howe bridge design and material affected von Mises stresses as well as stresses at Z direction. As a method, it was used a finite element analysis (linear-elastic) by Autodesk F-360. Half of a bridge was designed (one bridge side) and loaded with a central higher load and two equal smaller lateral loads. In essence, von Mises stresses (s) and stress at Z direction (sz) decreased on stresses values until a certain design change, which was proportional to a raise of mass due to beams added on the trusses. With a change of material to a lighter metal, from steel to aluminum, it was possible to overcome the mass drawback brought by steel and utterly possible to end up for a more effective design for a Howe truss bridge by applying minimal design changes.

Optimizing real-life engineering design problems are challenging and somewhat difficult if optimum solutions are expected. The development of new efficient optimization algorithms is crucial for this task. In this paper, a recently invented grasshopper optimization algorithm is upgraded from its original version. The method is improved by adding an elite opposition-based learning methodology to an elite opposition-based learning grasshopper optimization algorithm. The new optimizer, which is elite opposition-based learning grasshopper optimization method (EOBL-GOA), is validated with several engineering design probles such as a welded beam design problem, car side crash problem, multiple clutch disc problem, hydrostatic thrust bearing problem, three-bar truss, and cantilever beam problem, and finally used for the optimization of a suspension arm of the vehicles. The optimum results reveal that the EOBL-GOA is among the best algorithms reported in the literature.

Self-compacting concrete is highly advanced concrete with much higher fluidity without segregation, bleeding and it is suitable for placing in structures with congested reinforcement of structure like Vierendeel truss under its self-weight without vibration. Mix proportion of self-compacting concrete must ensure a good balance between deformability and stability. Behavior of concrete can be affected by the characteristics of selected ingredients in concrete and the mix proportions. It becomes necessary to evolve a procedure for mix design of SCC. The paper presents an experimental procedure for the mix design of self-compacting concrete for grade M60 and implementation of the same mix at cast in situ heavily dense reinforcement structure-Vierendeel truss of Sitabuldi Metro Station in Nagpur Metro Project. The test results for acceptance characteristics of M60 grade self-compacting concrete such as slump flow, V-funnel, L-box, compressive strength at the ages of 7, 28, and 56 days determined, and results are included here. Successful production of temperature control self-compacting concrete from batching plant, transportation and placement procedures and proper planning of handling and execution of self-compacting concrete at site are presented in this article.

Small-diameter round timber is a kind of by-product mainly from the thinning operation of the plantations. It is plentiful and inexpensive, and is generally destined for non-structural applications...

Background Active human body models (AHBM) consider musculoskeletal movement and joint stiffness via active muscle truss elements in the finite element (FE) codes in dynamic application. In the latest models, such as THUMS™ Version 5, nearly all human muscle groups are modeled in form of one-dimensional truss elements connecting each joint. While a lot of work has been done to improve the active and passive behavior of this 1D muscle system in the past, the volumetric muscle system of THUMS was modeled in a much more simplified way based on Post Mortem Human Subject (PMHS) test data. The stiffness changing effect of isometric contraction was hardly considered for the volumetric muscle system of whole human body models so far. While previous works considered this aspect for single muscles, the effect of a change in stiffness due to isometric contraction of volumetric muscles on the AHBM behavior and computation time is yet unknown. Methods In this study, a simplified frontal impact using the THUMS Version 5 AM50 occupant model was simulated. Key parameters to regulate muscle tissue stiffness of solid elements in THUMS were identified for the material model MAT_SIMPLIFIED_FOAM and different stiffness states were predefined for the buttock and thigh. Results During frontal crash, changes in muscle stiffness had an effect on the overall AHBM behavior including expected injury outcome. Changes in muscle stiffness for the thigh and pelvis, as well as for the entire human body model and for strain-rate-dependent stiffness definitions based on literature data had no significant effect on the computation time. Discussion Kinematics, peak impact force and stiffness changes were in general compliance with the literature data. However, different experimental setups had to be considered for comparison, as this topic has not been fully investigated experimentally in automotive applications in the past. Therefore, this study has limitations regarding validation of the frontal impact results. Conclusion Variations of default THUMS material model parameters allow an efficient change in stiffness of volumetric muscles for whole AHBM applications. The computation time is unaffected by altering muscle stiffness using the method suggested in this work. Due to a lack of validation data, the results of this work can only be validated with certain limitations. In future works, the default material models of THUMS could be replaced with recently published models to achieve a possibly more biofidelic muscle behavior, which would even allow a functional dependency of the 1D and 3D muscle systems. However, the effect on calculation time and model stability of these models is yet unknown and should be considered in future studies for efficient AHBM applications.

This paper investigates the macroscopic anisotropic behavior of periodic cellular solids with rigid-jointed microscopic truss-like architecture. A theoretical matrix-based procedure is presented to calculate the homogenized stiffness and strength properties of the material which is validated experimentally. The procedure consists of four main steps, namely, (i) using classical structural analysis to determine the stiffness properties of a lattice unit cell, (ii) employing the Bloch’s theorem to generate the irreducible representation of the infinite lattice, (iii) resorting to the Cauchy–Born Hypothesis to express the microscopic nodal forces and deformations in terms of a homogeneous macroscopic strain field applied to the lattice, and (iv) employing the Hill–Mandel homogenization principle to obtain the macro-stiffness properties of the lattice topologies. The presented model is used to investigate the anisotropic mechanical behavior of 13 2D periodic cellular solids. The results are documented in three set of charts that show (i) the change of the Young and Shear moduli of the material with respect to their relative density, (ii) the contribution of the bending stiffness of microscopic cell elements to the homogenized macroscopic stiffness of the material, and (iii) polar diagrams of the change of the elastic moduli of the cellular solid in response to direction of macroscopic loading. The three set of charts can be used for design purposes in assemblies involving the honeycomb structures as it may help in selecting the best lattice topology for a given functional stiffness and strength requirement. The theoretical model was experimentally validated by means of tensile tests performed in additively manufactured Lattice Material (LM) specimens, achieving good agreement between the results. It was observed that the model of rigid-joined LM (RJLM) predicts the homogenized mechanical properties of the LM with higher accuracy compared to those predicted by pin-jointed models.

Direct design using nonlinear inelastic analysis has been recently enabled for structural design as this approach can directly predict the behaviour of a structure as a whole, which eliminates capacity checks for individual structural members. However, the use of direct design is often accompanied by excessive computational efforts, especially for complicated structural design problems such as optimization or reliability analysis. In this study, we introduce an efficient method for the sizing optimization of truss structures employing nonlinear inelastic analysis for the direct design of structures. The objective function is the total weight of the structure while the strength and serviceability constraints are evaluated with nonlinear inelastic analysis. To save computational cost, an improved differential evolution (DE) algorithm is employed. Compared to the conventional DE algorithm, the proposed method has two major improvements: (1) a self-adaptive mutation strategy based on the p-best method to enhance the balance between global and local searches and (2) use of the multi-comparison technique (MCT) to reduce redundant structural analyses. The numerical results of a 72-bar truss case study demonstrate that the performance of the proposed method has significant advantages over the traditional DE method.

There is imprecision in the stage of construction because of manual quality control in the construction procedures. Forming and processing point clouds image of as is truss part with its CAD data are researched to identify and repair the geometric discrepancies and imprecision. Approved suggested technique of processing building model was done. Instead of manual processing of the 3D models points. BPNN architecture give the best coordinates processing training. It is applied to optimize the points forming process between the input laser scanned coordinates of the as-built model with the output true CAD coordinates. RMSE in x, y, xy, z and space vector R of all processing tasks are computed acceptably.