Search

The paper presents studies concerning the load-bearing capacity of truss joints with a positive eccentricity resulting from the arrangement of geometric members and the failure mechanisms observed in the joints. Based on the previously conducted experimental study, a numerical model of the tested fragment of the CFS truss with eccentricity in the joint was created and validated. All structural details of the tested truss and the loading method consistent with the experiment were taken into account. The results obtained from a uniaxial tensile tests on a steel samples and results estimated during destructive tests carried out on a full-scale of research model were taken into account in validation of the numerical model. Next, appropriate numerical analyses were carried out and parameters such as the eccentricity size in the joint and the wall thickness of sections (t = 1.0, 1.5 and 4.0 mm) were modified. In the range of the studied wall slenderness from λ > 70 (1.0 mm and 1.5 mm thick), it was confirmed that the resistance of truss joints made from CFS open cross-sections with a positive eccentricity, is greater than the resistance that results from known methods of steel structure dimensioning.

The article presents a new didactic tool helping in teaching the structures of students of the Faculty of Architecture. It is an attempt to solve the problem related to the difficulties in teaching structural systems among students of architecture. In the beginning, examples of Graphic-Statics tools supporting an intuitive understanding of the construction work are presented. Then a physical model of the truss was implemented, which responsively presents the values of internal forces using the colors of the luminous bars. The main part of the article describes the design elements of the truss model and presents how it works. Then, the influence of the model on the education of architecture students was checked by means of a questionnaire study. The results showed the great educational usefulness of the proposed solution.

He geometry of the flat statically determinate truss with two fixed hinge supports is specified by the lengths of the rods, the number of panels in supporting parts and the number of panels in the bolt. By induction on these parameters the General formulas for the deflection of the trusses under the action of concentrated and distributed load are obtained. Symbol conversions are performed in the system of computer mathematics Maple. The asymptotic properties of solutions are found. Formulas for reactions of supports and efforts in the most compressed and stretched the rods of the truss are found

The problems of experimental and theoretical research on the stressed and deformed state of steel structures under emergency actions are particularly relevant. Тhis paper proposes experimental and theoretical research methodology, which is used on the basis of an example of research on a full-length truss as part of the frame for an industrial buildings workshop. Components of the stressed-strained state of the structure are determined experimentally in the course of a simulated emergency situation. As emergency impacts, this paper considers the detachment of the air-cooling unit attached to a node of the lower chord of the truss. Experimental data is gathered through the joint use of the crate system, cable sensor and PC. The finite-element modelling of the structure behavior is performed based on the direct integration of differential equations of motion of the system subject to the local dynamic effects, and a comparison of data obtained with experiments results. As a result of using the test methodology we obtained the maximum weight of technological equipment fastened to the roof truss, while ensuring its normal operation in case of an emergency related to the failure to affix the equipment.

The complex problem of truss structural optimization, based on the discrete design variables assumption, can be approached through optimizing aspects of sizing, shape, and topology or their combinations. This paper aims to show the differences in results depending on which aspect, or combination of aspects of a standard 10 bar truss problem is optimized. In addition to standard constraints for stress, cross section area, and displacement, this paper includes the dynamic constraint for buckling of compressed truss elements. The addition of buckling testing ensures that the optimal solutions are practically applicable. An original optimization approach using genetic algorithm is verified through comparison with literature, and used for all the optimization combinations in this research. The resulting optimized model masses for sizing, shape, and topology or their combinations are compared. A discussion is given to explain the results and to suggest which combination would be best in a generalized example.

In the article the influence of the dependence of the degree of surface corrosion on the bearing capacity of the most loaded rods metal truss made of profiles such as “Molodechno”. The study plotted strength, flexibility-sti and local stability of the wall on the degree of corrosion damage in truss belts surfactant corrosion. It is concluded that the intensity of the exhaustion of the bearing capacity of the elements of the truss, depending on the speed of propagation of corrosion processes.

A statically determinate flat truss models the industrial facility's arch. To derive dependence of structural deflection on the number of panels in a span, the Maxwell–Mohr equation, computer mathematics system Maple and the induction method are applied. Forces in the rods are determined by the method of cutting nodes. Several cases of loading are considered: uniformly distributed along the top and bottom chords, uniformly distributed along the lateral surface, and by concentrated force. For analytical assessment of the structural strength, equations for forces in the most compressed and tensioned rods and equation for support displacement are derived. Asymptotics of the solution for the number of panels at the fixed span length, and total load is found.

In this study was to evaluate the impact of the truss structure on stiffness and stress distribution in the truss structural members. Made and synchronizes this structures with any Populus_ Nigra lumbers, in finally made 44 truss structure with 11 varying samples and 4 replicates. were used by two joint like friction joints was created with Glue stick and dual joint was created with nails to the 4.5 cm and calculate the resistance trusses structures by mechanical testing machine with 12.5 mm/min loading speed and 3.5 KN than mechanical test results showed, Hip Girder truss most resistance stress distribution and were the least impact on the strength and distribution of tension truss structure is significant in 95%. To show the stress distribution on the members, modeling software was AutoCAD, Catia and finite element analysis software was ANSYS. In finally the results show that maximum stress concentration, failure to engage in experimental mode.

A trussed supporting structure with carbon fiber trusses and titanium frames was designed to meet the requirements on precision and mass of a light-small off-axis three-mirror reflective space camera. After analyzing the common forms of the supporting structure for space cameras,a method of the supporting structure with the secondary mirror and the folding mirror fixed separately was determined according to the structure characteristics of this optical system. A dynamic size optimization was conducted to lighten the structure and improve the stiffness of this structure. After the size optimization the finite element analysis and vibration experiments were conducted. It shows that the supporting structure could satisfy the requirements on precision and mass of this camera,and the fundamental frequency reaches 291.4Hz under the condition that the mass of this trussed supporting structure is not more than 4Kg. The design scheme of this trussed supporting structure could provide some references to the other light-small space cameras with the same type.

We propose a scheme of a statically determinate truss with straight chord s and four supports, one of which is a fixed hinge, the other movable hinges. The task is to obtain the dependence of the deflection of the middle span of the structure on the number of panels. The problem is solved by induction using operators of the Maple computer mathematics system. The deflection is determined by the Maxwell – Mohr's formula, the forces in the rods are found from the solution of the joint system of the equation of equilibrium of nodes, the unknowns of which include the reaction of the supports. of nodes, whose unknowns include the reaction of the supports. The inclusion of support reactions in the system of equilibrium equations allows us to reveal the external static indeterminability of the structure. Generalizing a number of solutions for trusses with a consistently increasing number of panels, the desired dependence is obtained. To do this, we create recurrent equations that satisfy the terms of the sequences of coefficients in the deflection formula. The resulting homogeneous linear recurrent equations have a degree no higher than the eighth in the case of a problem with a load distributed over the upper chord and the sixth for a concentrated load in the middle of the span. Solving these equations in the Maple environment using the rsolve operator gives expressions of the dependence of the coefficients of the desired formula on the number of panels. The asymptotics of solutions are found. The dependence of the horizontal shift of the mobile support on the action of distributed and concentrated load is also obtained. Formulas are derived for the dependence on the number of panels of forces in some elements in the middle of the span. The obtained solutions can be used for preliminary evaluation of the designed structure and for evaluating the accuracy of numerical solutions.

Advances in additive manufacturing across scales have enabled the creation of random, periodic, or hierarchical truss networks containing millions and more of individual truss members. In order to significantly reduce computational costs while accurately capturing the dominant deformation mechanisms, we introduce a simple yet powerful homogenized continuum description of truss lattices, which is based on applying a multi-lattice Cauchy–Born rule to a representative unit cell (RUC). Beam theory applied at the level of the RUC introduces rotational degrees of freedom and leads to a generalized continuum model that depends on the effective deformation gradients, rotation, and curvature on the macroscale. While affinely deforming the RUC is shown to produce excellent results for simple Bravais lattices, a multi-lattice extension is required for general and especially bending-dominated lattices, which cannot be described by a pure Taylor expansion of the RUC deformation; the importance of the multi-lattice concept is demonstrated through analytical examples. The resulting method is a beneficial compromise between inefficient FE2 techniques and micropolar theories with limited applicability. By implementing the model within a finite element framework, we solve and report several benchmark tests in 2D to illustrate the accuracy and efficiency of the model, which comes with only a small fraction of the computational costs associated with the full, discrete truss calculation. By using a corotational beam description, we also capture finite beam rotations. We further demonstrate that a second-gradient homogenization formulation is beneficial in examples involving localization, providing higher local accuracy at the RUC level than a first-gradient scheme, while affecting the global response only marginally. [ABSTRACT FROM AUTHOR]

In this paper truss layout optimization is used in conjunction with geometry optimization to provide the basis for a powerful conceptual design tool for additively manufactured (AM) components, particularly useful when the degree of design freedom is high. With layout optimization the design domain is discretized using a grid of nodes which are interconnected with discrete line elements, forming a 'ground structure'. Linear optimization can then be used to identify the subset of elements forming the minimum volume structure required to carry the applied loading. A nonlinear geometry optimization step, which involves adjusting the positions of the nodes, can subsequently be undertaken to simplify and improve the solution. Simple geometrical rules can then be used to automatically transform a line element layout into a 3D continuum, ready for validation and/or manufacture. Various extensions to the basic method are described in the paper, including AM build direction constraints and techniques to permit user-interaction with candidate designs, which has been found to be invaluable at the conceptual design stage. Finally the approach described is applied to a range of design problems, including the redesign of an airbrake hinge for the Bloodhound Supersonic Car. [ABSTRACT FROM AUTHOR]

Most real-world engineering problems deal with multiple conflicting objectives simultaneously. In order to address this issue in truss optimization, this paper presents a multi-objective genetic programming approach for sizing and topology optimization of trusses. It aims to find the optimal cross-sectional areas and connectivities between the nodes to achieve a set of trade-off solutions to satisfy all the optimization objective functions subjected to some constraints such as kinematic stability, maximum allowable stress in members and nodal deflections. It also uses the variable-length representation of potential solutions in the shape of computer programs and evolves to the potential final set of solutions. This approach also employs an adaptive mutant factor besides the classical genetic operators to improve the exploring capabilities of Genetic Programming in structural optimization. The intrinsic features of genetic programming help to identify redundant truss members and nodes in the design space, while no violation of constraints occurs. Our approach applied to some numerical examples and found a better non-dominated solution set in the most cases in comparison with the competent methods available in the literature. [ABSTRACT FROM AUTHOR]

The authors present a case study carried out to know the relevance, in the resistance of the bars, of the eccentricity in the joints of a bridge with mixed spatial truss superstructure. This type of superstructures was built in a significant number in Mexico, from its technological development. This technique was proposed by Ing. Heberto Castillo Martínez in the 1960s (1). Some of these superstructures are still in use. In this article, the case study is the Santo Domingo bridge, on the river of the same name located in Chiapas, Mexico. As a first phase, the superstructure is analyzed considering the concentric bars in the joints. In a second phase, the flexing moments generated by the eccentricity in the mid-height joints of the tridilose are taken into account. The resistance of critical elements is calculated considering separately the effects of the axial loads, of the bending moments caused by the own weight and the flexion in the slab and the bending moments caused by the eccentricity of the bars in the joints. The authors conclude that approximately half of the resistance of the bars is required to take the bending moments caused by the eccentricity of the bars in the joints. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In an attempt to understand the origins and the nature of the law binding two group operations together into a skew brace, introduced by Guarnieri and Vendramin as a non-Abelian version of the brace distributive law of Rump and Cedó, Jespers, and Okniński, the notion of a skew truss is proposed. A skew truss consists of a set with a group operation and a semigroup operation connected by a modified distributive law that interpolates between that of a ring and a brace. It is shown that a particular action and a cocycle characteristic of skew braces are already present in a skew truss; in fact the interpolating function is a 1-cocycle, the bijecitivity of which indicates the existence of an operation that turns a truss into a brace. Furthermore, if the group structure in a two-sided truss is Abelian, then there is an associated ring--another feature characteristic of a two-sided brace. To characterize a morphism of trusses, a pith is defined as a particular subset of the domain consisting of subsets termed chambers, which contains the kernel of the morphism as a group homomorphism. In the case of both rings and braces piths coincide with kernels. In general the pith of a morphism is a subsemigroup of the domain and, if additional properties are satisfied, pith is an N+-graded semigroup. Finally, giving heed to ideas of Angiono, Galindo, and Vendramin, we linearize trusses and thus define Hopf trusses and study their properties, from which, in parallel to the set-theoretic case, some properties of Hopf braces are shown to follow. [ABSTRACT FROM AUTHOR]

Numerical layout optimization employing an adaptive 'member adding' solution scheme provides a computationally efficient means of generating (near-)optimum trusses for problems involving single or multiple load cases. To encourage usage of the method, a Python script is presented, allowing medium to large-scale problems to be solved efficiently. As well as handling multiple load cases, the short (98 line) script presented can tackle truss optimization problems involving unequal limiting tensile and compressive stresses, joint costs, and non-convex polygonal domains, with or without holes. Various numerical examples are used to demonstrate the efficacy of the script presented. [ABSTRACT FROM AUTHOR]

• An interactive and integrative approach to truss design is proposed by developing a Grasshopper component for simultaneous optimization of geometry and topology of trusses. • Numerical difficulty due to melting nodes can be successfully avoided using force density as design variable, and various optimal geometry and topology can be obtained. • Tensor product Bezier surface is introduced as a design surface to control optimal shapes. • Efficiency and accuracy of the proposed method are demonstrated through two numerical examples of semi-cylindrical and semi-spherical models. This paper presents a new efficient tool for simultaneous optimization of topology and geometry of truss structures. Force density method is applied to formulate optimization problem to minimize compliance under constraint on total structural volume, and objective and constraint functions are expressed as explicit functions of force density only. This method does not need constraints on nodal locations to avoid coalescent nodes, and enables to generate optimal solutions with a variety in topology and geometry. Furthermore, for the purpose of controlling optimal shapes, tensor product Bézier surface is introduced as a design surface. The optimization problem is solved using sensitivity coefficients and the optimizer is compiled as a component compatible with Grasshopper, an algorithmic modeling plug-in for Rhinoceros, which is a popular 3D modeling software. Efficiency and accuracy of the proposed method are demonstrated through two numerical examples of semi-cylindrical and semi-spherical models. [ABSTRACT FROM AUTHOR]

This paper presents the experimental and analytical studies of double-chorded composite truss system connected using stainless steel through-bolts with mechanical inserts. The composite trusses were assembled using rectangular hollow sections of pultruded glass fibre reinforced polymer (GFRP) where adhesively bonded mechanical inserts were introduced at the vicinity of the joining areas. The trusses were tested under 4-point bending (Load Case 1) and 3-point bending (Load Case 2). From this experimental program, the load-vertical deflection behaviour of the truss, internal forces distribution in the members and joint behaviour were investigated. The pultruded GFRP truss under Load Case 1 was capable of resisting the maximum load capacity of the testing equipment at 450 kN with the lowest factor of safety of 1.10 was attained by the external diagonal members. High axial compression forces experienced by the external diagonal members has exceeded the American pre-standard theoretical joint bearing capacity by 2%, and this was reflected by the minor bearing damage observed on the joints of these members. Meanwhile, the truss under Load Case 2 failed at 160 kN with the continuous top chords ruptured in flexural bending manner. The satisfactory comparisons between the Strand 7 truss model and experimental results demonstrated the validity of the adopted simplified numerical model. Additionally, the theoretical strength limits of pultruded GFRP truss members in tension, compression and flexural according to American pre-standard are in close agreement with the experimental results. [ABSTRACT FROM AUTHOR]

Subtalar joint distraction arthrodesis has been recommended for the treatment of conditions such as nonunion or malunion of subtalar joint arthrodesis posttraumatic arthritis. Both conditions are difficult to treat, because the deformities created in the frontal and sagittal planes of these conditions are complex. If these malalignments are not addressed, ankle joint instability and wear occur over time. In general, either autograft or allograft bone has been used to perform distraction arthrodesis of the subtalar joint. Although studies have shown successful use, there have been complications. Autografts have resulted in donor site morbidity and limitations on graft size, and allografts have shown high nonunion rates. Both autografts and allografts have shown graft collapse over time. Recent literature has discussed the use of tantalum technology to span large defects in bone healing. Studies have shown that tantalum provides superior strength and bone incorporation compared with autografts and allografts. This case series presents 2 cases in which tantalum truss technology was used for distraction arthrodesis. Although this series is limited in patient numbers, both cases show effective graft incorporation with no loss in height over time and earlier return to activity compared with previous studies that used autograft and allograft wedges. [ABSTRACT FROM AUTHOR]

The study of wooden plate bamboo connection system with the addition of wooden clamp was carried out taking into account the variety the angle of the stems at the joint. The loading was preceded through the application of compressive force at the joint’s member understudied up to reaching the maximum load and the connection was collapsed. It is known that the strength of bamboo not parallel to the direction of the fiber is lower than those parallel to fiber. Therefore, the strength of connection must be determined considering the strength of bamboo not parallel to the fiber direction. The experiment was carried out under static loading on the bamboo truss connections model with the various angle of connection stems of 0°, 30° and 45° toward bamboo fiber direction. From the test result, it was found that there is a decrease in the connection strength at stem angle of 30° and 45° for about 16,80% and 12,21%, respectively, compared to the strength of the stem angle of 0°. The test results also resulted the value of average elastic stiffness (Se) of the connection also indicates a decrease in the of elastic stiffness value (Se) of the connection for the stem’s angle 30° and 45° for about 42,62% and 82,95%, respectively, compared to stem angle of 0°. It can be concluded that there is a decrease in the strength and stiffness of the joints along with the increase in stem’s angle of the bamboo truss connection system using wooden plate and clamp. [ABSTRACT FROM AUTHOR]

In order to understand the structure of the “typical” element of an automorphism group, one has to study how large the conjugacy classes of the group are. When typical is meant in the sense of Baire category, a complete description of the size of the conjugacy classes has been given by Kechris and Rosendal. Following Dougherty and Mycielski, we investigate the measure theoretic dual of this problem, using Christensen’s notion of Haar null sets. When typical means random, that is, almost every with respect to this notion of Haar null sets, the behavior of the automorphisms is entirely different from the Baire category case. In this paper we generalize the theorems of Dougherty and Mycielski about S∞ to arbitrary automorphism groups of countable structures isolating a new model theoretic property, the cofinal strong amalgamation property. As an application, we show that a large class of automorphism groups can be decomposed into the union of a meager and a Haar null set. [ABSTRACT FROM AUTHOR]

Abstract Effective use of building materials for achieving sustainable construction is of prime importance today due to fast depletion of the natural resources by the construction industries for obtaining raw materials and aggregates. Precast insulated concrete sandwich panels (CSPs) consisting of two reinforced concrete wythes, an Expanded Poly-Styrene (EPS) core and truss-type shear connectors can be considered as an innovative construction material for acting as load bearing walls and floors in building systems. The two wythes are connected by the shear connectors through the EPS core for transferring shear forces (henceforth called as through-thickness shear) between the wythes and achieving composite action in the panels. In this paper, details of experimental studies conducted on small-scale precast CSP specimens under through-thickness shear loading are presented. The major parameters considered in the experimental program were the thickness of EPS core, gap between the wythes (in CSPs without EPS core), presence/absence of EPS core and number of shear connector lines. The effect of the major parameters on the failure mode, through-thickness shear strength, load vs relative displacement (between top and bottom wythes) behavior and load vs strain behavior of the CSPs are presented and discussed. The test results indicate that the through-thickness shear strength and behavior of the CSPs are significantly influenced by the parameters considered. Reduction in thickness of the EPS core and presence of the EPS core improved the through-thickness shear strength of the CSPs. [ABSTRACT FROM AUTHOR]

In order to find a more effective intelligent method for truss optimization, we proposed an improved bat algorithm and introduced it into truss optimization. The initial population was optimized by using the good point set weighted approach in bat optimization formula. Individuals with high fitness were retained and individuals with low fitness were eliminated. And the learning factor was introduced to enhance the global search ability of bat algorithm. The improved BA (bat algorithm) was applied to the topology optimization of truss and the optimization results were compared with other algorithms. Experiments show that the improved bat algorithm has better global optimization ability. This study provides an efficient algorithm for structural optimization. [ABSTRACT FROM AUTHOR]

Abstract This work documents the formulation of an axial element that could handle implicit constitutive relations. This formulation uses nodal displacements, member forces, and reaction forces as primary unknowns. For some assumed values of these primary unknowns satisfying the nodal equilibrium equations, the computed stretch and stress in the members need not be in agreement with the constitutive relation. Hence, these primary unknowns are found such that the error in the constitutive relation for the members are minimized subjected to the constraint that the nodal equilibrium equations hold. Axial element developed using this concept is used to analyze a few trusses. The results of this formulation are in agreement with the results obtained from ABAQUS® when stress is an explicit function of the stretch ratio. Also, some statically determinate as well as indeterminate trusses are solved for an implicit constitutive relation and the reasonableness of the obtained results established. Highlights • An alternative formulation for large deformation axial element. • Validation of the developed axial element for explicit constitutive relations. • Illustration of the developed axial element for implicit constitutive relations. [ABSTRACT FROM AUTHOR]

Highlights • A new composite bamboo culm-slat truss is presented. • Culm joints are based on thin steel clamps that apply circumferential compression. • Tested trusses did not fail at two times the service load. • Composite trusses can be used for floors and roofs according to the Colombian Standard. Abstract This study pertains to the design and structural testing of trusses assembled with culms and slats of the bamboo species Guadua angustifolia (GA). The trusses were constructed using a novel design of steel clamps to accomplish the connections between the top and bottom chord culms and the diagonal and vertical slat elements. The clamps offer a better alternative to the conventional joining methods that typically lead to longitudinal splitting of the culms, since the clamps counteract the formation of longitudinal splitting and accommodate themselves to the geometric irregularities of the culms and slats. The experimental program included the monotonic static tests of pilot Howe truss prototypes with variations in the clamp joints. Next, four replicates of the proposed design (3 m long and 0.4 m high weighing 265.4 N) were tested under monotonic static load. The trusses were simply supported at the ends and loaded at three central joints. The stiffness of the trusses up to 9869 N (1.5 times the service load for floor use) was 631.3 N/mm (COV 3.6%), and no failure was shown at the proof load of 13,754 N. This pilot study demonstrates that these trusses are a good candidate to substitute the traditional materials to support the floors and roofs in low-cost, prefabricated housing projects. However, more experimental studies have to be accomplished to fully validate this application. [ABSTRACT FROM AUTHOR]

In this paper, a novel optimization-based method is proposed to analyze steel space truss structures undergoing large deformations. The geometric nonlinearity is considered using the total Lagrangian formulation. The nonlinear solution is obtained by introducing and minimizing an objective function subjected to the displacement-type constraints. The proposed approach can fully follow the equilibrium path of the geometrically nonlinear space truss structures not only before the limit point, but also after it, namely, including both the pre- and post-buckling paths. Moreover, a direct estimation of the buckling loads and their corresponding displacements is possible by using the method. Particularly, it has been shown that the equilibrium path of a structure with highly nonlinear behavior, multiple limit points, snap-through, and snap-back phenomena can be traced via the proposed algorithm. To demonstrate the accuracy, validity, and robustness of the proposed procedure, four benchmark truss examples are analyzed and the results compared with those by the modified arc-length method and those reported in the literature. [ABSTRACT FROM AUTHOR]

Abstract High fat diet (HFD)-induced obesity is associated with insulin resistance (IR) and other chronic, diet associated illnesses, including neuroinflammation and brain injury. However, the involvement of inflammatory response in HFD-elicited central nerve injury has yet to be fully determined. Recent studies have indicated that tumor necrosis factor receptor-associated ubiquitous scaffolding and signaling protein (TRUSS), also known as TRPC4AP, plays an essential role in regulating inflammation via the meditation of NF-κB signaling. In the present study, we attempted to explore the effects of TRUSS on HFD-induced brain injury in the wild type mice (TRUSS+/+) or TRUSS-knockout mice (TRUSS−/-). The results suggested that TRUSS deletion attenuated HFD-induced cognitive impairments in mice. HFD-elicited metabolic disorders were also highly improved by the loss of TRUSS, as evidenced by the reduced serum glucose and insulin levels, as well as the lipid deposition in liver tissues. In addition, HFD-triggered brain injury was markedly alleviated by the TRUSS ablation, as proved by the reduction of GFAP and Iba1 expressions in hippocampus and hypothalamus. Moreover, TRUSS−/- mice exhibited a significant decrease in the expression of pro-inflammatory cytokines, accompanied with the inactivation of IKKα/IκBα/NF-κB pathway. At the same time, HFD-induced dyslipidemia was also alleviated by the loss of TRUSS. The in vitro study verified the protective effects of TRUSS-suppression against HFD-induced central nerve injury and hepatic steatosis by restraining the inflammatory response. In summary, our data indicated that TRUSS participated in metabolic syndrome-induced brain injury and pointed to the repression of TRUSS as a promising strategy for cognitive deficits therapy. Highlights • TRUSS ablation alleviates HFD-induced cognitive impairments and metabolic disorder. • TRUSS deletion attenuates the hippocampus and hypothalamus injury in HFD-fed mice. • TRUSS suppression attenuates inflammatory response in astrocytes and BV2 cells treated by LPA or PA. [ABSTRACT FROM AUTHOR]

Abstract Considerations presented in this paper focus on the assessment of steel truss fire safety with the use of the system reliability analysis. In calculations of capacity and the effect of actions, random variation in the Young's modulus, yield strength and the cross-sectional areas of rods are taken into account. The aim of the analysis is to monitor the reliability index in the consecutive minutes of the fire. That allows estimation of the failure probability, and also taking decisions on whether the required safety level is ensured. The new method described in the paper makes it possible to take into account changes in the structure static scheme under fire conditions. [ABSTRACT FROM AUTHOR]

Highlights • Flexural response of cold-formed steel floor trusses is studied experimentally. • CFS section thickness and diagonal-chord connection detail are considered as test variables. • Elastic analysis overpredicts truss service stiffness due to neglect of connection flexibility. • Experimentally determined strain profiles indicate nonuniform strains in truss chords. • Considering local buckling of CFS section with unfolded lips results in accurate strength prediction. Abstract This paper reports findings of an experimental study on floor trusses fabricated from cold-formed steel lipped channel sections. In design, the members of these trusses are generally considered as pin-ended and their capacities are assessed under pure compressive and tensile loads by making use of commonly accepted design specifications. Seventeen full-scale floor trusses were experimentally investigated through four point bending tests. Thickness of lipped channels, number of connection fasteners, and type of diagonal connection were considered as the prime variables. Test results indicate that there are marked differences between the design and measured values in terms of both the strength and stiffness. The service load stiffnesses of the trusses were found to be lower than the stiffnesses obtained using two dimensional truss models due to the neglect of connection flexibility in analysis models. Additional experiments on screw connections were conducted to find out their axial stiffness. The results from connection tests were used to develop analytical expressions which can be used to simulate connection flexibility. Similar to the stiffness, the strength of the trusses were found to be lower than the predicted strength using the pin-ended member under compression approach. In addition, the observed failure modes are markedly different than the code predictions. The sources of these differences were found to arise from the unfolding of lips at the diagonal to chord member connections and the global bending effects. The strength and failure mode of trusses can be more accurately predicted by considering local buckling of channel sections with unfolded lips. [ABSTRACT FROM AUTHOR]

Highlights • Stress Concentration Factors (SCFs) are established for novel truss chord-brace welded joints. • Chord is a concrete-filled square hollow section stiffened with Perfobond Leister (PBL) ribs. • Joints with varying dimensions were first tested to measure hot spot stresses. • 3D FE models were developed and verified then used in comprehensive parametric study. • Design equations for SCF were developed based on multiple regression analysis of database. Abstract A novel tubular joint of concrete-filled square hollow section (CFSHS) chord welded to an SHS brace was studied experimentally and numerically to establish design equations for Stress Concentration Factors (SCFs) for fatigue design purposes. The chord was stiffened with internal perfobond ribs longitudinally welded to the inner faces. A series of joints with varying member sizes and wall thicknesses were first tested under axial force in the brace and the hot spot stresses were carefully measured. Three-dimensional finite element models were developed and validated with the experimental results. A comprehensive parametric study was then conducted on 90° T- and X-joints with perfobond ribs, to establish correlations between SCF and three key non-dimensional geometric parameters: brace width-to-chord width (β), width-to-wall thickness ratio of the chord (2 γ), and brace wall thickness-to-chord wall thickness ratio (τ). Four basic loading conditions were examined: axial tension and in-plane bending in the brace, and axial tension and in-plane bending in the chord. Finally, a series of SCF formulae and design charts were proposed based on multiple regression analysis. It was shown that under brace axial tension stress concentrations reduced by one third and two thirds in CFSHS chords without perfobond ribs and with perfobond ribs, respectively, compared to a SHS chord. Current design guides which are based on SHS sections, overestimate SCFs significantly for CFSHS sections with perfobond ribs. [ABSTRACT FROM AUTHOR]

The present study goes into the search for the safety domain of civil engineering structures. The objective is to show how a reliability-evaluation brought by a mechanical sizing can be obtained. For that purpose, it is necessary to have a mechanical model and a reliability model representing correctly the behavior of this type of structure.It is a question on one hand, to propose a formulation for the nonlinear calculation (mechanical nonlinearity) of the spatial structures in trusses, and on the other hand, to propose or to adapt a formulation and a modeling of the reliability. The principle of Hasofer-Lind can be applied, in first approach, for the reliability index estimation, scenarios and the probability of failure.The made check concerned metallic in truss structures. Finally, some structures are calculated using the method adapted by Hasofer-Lind to validate the probability approach of the reliability analysis. [ABSTRACT FROM AUTHOR]

Taxonomic ambiguity exists in genus Systomus and recently many new species were described under this genus. Systomus sarana subnasutus is considered a valid subspecies of S. sarana sarana although revisions have been done by some researchers. We employed a combination of morpho-meristics and molecular tools (Cytochrome c oxidase I, 16S and Cytochrome b genes of mitochondrial genome) to resolve the two species. Three morpho-meristic characters, head length/maxillary barbel length (HL/MxBL), Lateral Line Scales (LLSs) as well as two truss-based characters, had discernible variation between the two taxa. The sequence analysis (2353 nucleotides) depicted a separate clad of S. sarana subnasutus with high bootstrap support. The findings from combined use of morphology, meristics and mitogenes were concordant. The corroborative results suggest the possibility of two different species. The results suggest to adopt suitable management measures, accordingly. [ABSTRACT FROM AUTHOR]

In this study, experimental tests were performed to evaluate the shear performance of encased steel truss (EST) composite girders that can resist loads at construction and composite stages. Four full-scale EST composite girders were fabricated, where the truss type (Pratt truss and Warren truss) and presence of stirrups were set as main test variables. The test results showed that in specimens applied with the Pratt truss, horizontal shear cracking occurring along the interface between concrete and steel was the dominant failure mode. Based on the crack pattern and failure plane observed from the test, the horizontal shear strengths of the Pratt truss specimens were calculated, which provided conservative results. On the other hand, in the specimens with the Warren truss inside, the strengths of the specimens were governed by the shear failure occurring in the screw rod connecting the truss elements prior to the yielding of the diagonal member. The shear strengths of the Warren truss specimens calculated based on the shear failure of the screw rod were similar to that obtained from the test.

The scheme of statically definable truss of spatial coverage is proposed. The formula for the dependence of the vibration frequency on the number of panels is derived. The Dunkerley lower bound and the induction method are used to generalize particular solutions to the case of an arbitrary number of panels. The calculation of the forces in the rods by cutting out the nodes and the analytical transformations to obtain the desired dependence are performed in the Maple computer mathematics system. The solution is compared with the numerical one obtained by solving the problem on the eigenvalues of the characteristic matrix for a system with many degrees of freedom. It is shown that the estimation accuracy depends on the number of panels.

In this paper, the author proposes a regular option of statically determinate flat truss with a lattice of Shukhov's type working under beam scheme. By induction, using Maple computer algebra system, the exact formula for the mid-span deflection under the action of the uniform load is obtained. The deflection of the elastic structure is defined by the formula of Maxwell – Mohr. Forces in the rods are found using cut nodes method with the composition of the management of the matrix of equations in vector form. The analysis of the coefficients in the truss evaluation with a different number of panels revealed the recurrence equation satisfied by these coefficients, and then the determined operators of a specialized package genfunc give a solution of the resulting equation that determines the required general formula. The case of a uniform load on the top horizontal zone is considered. The author obtained a simple asymptotic evaluation of this solution, proving the cubic nature of the growth of deflection for a fixed span length and a given nodal load. The solution found for an even number of panels and rods of the same cross-section, has a polynomial form; the dependence is non-monotonic and detects extremum, which allows optimizing the design.

We have obtained an analytical expression for the deflection and forces in the rods of a flat truss of beam type in the elastic stage. We found that the induction method, which has been tested for a wide class of two-dimensional elastic and regular trusses, does not yield a direct and compact result for trusses with an inclined upper chord. Decomposing the deflection into a series of a small parameter characterizing the slope is only suitable for very small tilts that are not typical for real practical application. The formulas for the forces in the rods of the truss include the geometrical and physical parameters, the number of a rod in the belt or grid, and the number of panels. The asymptotics of the solution for the deflection taking into account the different rod stiffnesses (the slope of the upper belt is random) were found. All the analytical transformations were executed in the Maple computer algebra system.