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The traditional new Austrian tunneling method (NATM) is inadequate for handling the excavation and support of deep soft-rock tunnels with significant deformation. Therefore, new steel structures and materials are needed to effectively manage such complex conditions. This study utilizes the coupling technology of negative Poisson's ratio (NPR) anchor cable structures and double-layer three-dimensional truss structures, as proposed by Academician He Manchao. Mechanical models, numerical simulations, and field monitoring were employed to investigate the support of large deformation soft-rock tunnels traversing multi-stage fault-fracture zones for the first time. The findings indicate that the support technology combining the flexible control and rigid constraint of "NPR anchor cable + double-layer three-dimensional truss" demonstrates remarkable mechanical compensation for large deformation in soft-rock tunnels. This approach effectively controls tunnel deformation to below 300 mm and maintains a constant resistance value around 350kN. This research provides a scientific basis for supporting other large-deformation soft-rock tunnels across multi-stage fault-fracture zones. Highlights: A comprehensive study of soft-rock large deformation tunnels across multi-stage faults has been carried out through numerical simulations, field monitoring and physical modeling tests. The first experimental study of stress compensation in soft-rock large deformation tunnels across multi-stage faults First coupling application of NPR anchor cables with negative Poisson's ratio effect structures to truss structures [ABSTRACT FROM AUTHOR]

This paper presents an efficient decoding method (namely SORTED decoding) for the de facto encoding in size optimization of trusses with automatic member grouping. The efficiency of the proposed method is evaluated through numerical experiments driven by two metaheuristic algorithms of different search mechanisms: Colliding Bodies Optimization and Jaya Algorithm. The first group of experiments show that the SORTED decoding method significantly outperforms the de facto and the two other decoding methods introduced in this study (ACCUMULATED and SORTED-ACCUMULATED) in terms of solution quality; moreover, the authors proved that the superiority of the SORTED decoding is not algorithm-dependent. Considerably better member-grouping configurations that provide up to 15% material economy are discovered for some of the well-known pre-grouped benchmark problems in the second group of experiments; surprisingly, the worst member-grouping configuration discovered by the SORTED decoding for one of the problems is better than that of the pre-grouped version. [ABSTRACT FROM AUTHOR]

Curved shells are increasingly utilized in applied engineering due to their shared characteristics with other sandwich structures, flexibility, and attractive appearance. However, the inability of controlling and regulating vibrations and destroying them afterward is a challenge to scientists. In this paper, the curve shell equations and a linear quadratic regulator are adopted for the state feedback design to manage the structure vibrations in state space forms. A five-layer sandwich doubly curved micro-composite shell, comprising two piezoelectric layers for the sensor and actuator, is modeled by the fourth-order shear deformation theory. The core (honeycomb, truss, and corrugated) is analyzed for the bearing of transverse shear forces. The results show that the honeycomb core has a greater effect on the vibrations. When the parameters related to the core and the weight percentage of graphene increase, the frequency increases. The uniform distribution of graphene platelets results in the lowest natural frequency while the natural frequency increases. Furthermore, without taking into account the piezoelectric layers, the third-order shear deformation theory (TSDT) and fourth-order shear deformation theory (FOSDT) align closely. However, when the piezoelectric layers are incorporated, these two theories diverge significantly, with the frequencies in the FOSDT being lower than those in the TSDT. [ABSTRACT FROM AUTHOR]

Typical household recyclable bin in Australia contains around 60% of waste cardboard. Given the possibilities of developing a construction material, this study conducted a life cycle assessment (LCA) comparing the development of cardboard trusses with © timber trusses, encompassing production to construction. The results show that cardboard trusses offer significant environmental benefits, including a 73% reduction in climate change category, an 83% decrease in ozone-depleting potential, and almost complete avoidance of agricultural land occupation compared to timber trusses, showcasing their sustainability. In both material manufacturing and material transportation, cardboard trusses prioritize climate change mitigation, accounting for over half of the environmental impact. Timber trusses, in contrast, heavily impact land occupation and exhibit climate change dominance. A benefit analysis highlights advantages of cardboard trusses, particularly in reducing land occupation, sustainability, circular economy, and particulate matter formation. The life cycle cost analysis demonstrates an impressive 83% cost reduction for cardboard trusses compared to timber trusses, despite higher labor costs during manufacturing. [ABSTRACT FROM AUTHOR]

Introduction. Quantitative assessment of the structural reliability and safety level for structural solutions is an actual scientific and technical problem. The measure of reliability in this case can be the failure probability of a structural element. In practical problems of assessment and analysis of structural reliability, data on random variables can be obtained in the interval form (qualitative uncertainty), while the classic methods of reliability analysis do not allow to estimate reliability in the presence of such data. Lack of statistical data (quantitative uncertainty) is also present in practical tasks of reliability analysis.Materials and methods. The paper considers the use of the theory of evidence as an effective tool for reliability analysis of steel span structures in problems with interval uncertainty of statistical data.Results. The graphical interpretation of the reliability analysis algorithm is given. It allows to obtain clearly and operatively an estimate of the failure probability of the structural element, as well as to reduce the permissible load on the element to the required reliability level. Two-dimensional and three-dimensional models are considered for analyzing the reliability of a steel truss bar according to the buckling criterion.Conclusions. The theory of evidence allows effective modelling of various sources of uncertainties in practical engineering problems. Thus, with limited data, it is possible to get an idea of the quantitative expression of the reliability level by its lower bound, which can be increased by strengthening the element, more detailed probabilistic analysis or limiting the operational load on the structural element. By considering more non-deterministic quantities in the design, the engineer obtains a more cautious decision. When considering the cross-sectional area as a random variable, the reliability of the truss bar on the buckling was 23 % lower (lower reliability bound) than in a similar calculation with a deterministic value.

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Kinematic instability due to unstable nodes is an often neglected but critical aspect of mathematical optimization models in truss topology optimization problems. On the one hand, kinematically unstable structures cannot be used in the actual structural design. On the other hand, unstable nodes within continuous parallel bars can make the calculation of bar length wrong and affect the optimization effect. To avoid kinematic instability, a computationally efficient nominal disturbing force (NDF) approach for truss topology optimization is presented in this paper. Using the NDF approach, the most favorable structure for the optimization goal can be selected in three schemes: (1) adding bracings at unstable nodes, (2) removing unstable nodes and replacing short bars with long ones, or (3) selecting a new topology form to avoid containing unstable nodes. Compared with the widely used nominal lateral force (NLF) approach in the literature, the NDF approach can not only improve the optimization efficiency but also obtain lighter optimization results. Moreover, using the NDF approach, a mixed-integer linear optimization model for minimizing the weight of truss with discrete cross-sectional areas subject to constraints on kinematic stability, bar buckling, allowable stress, nodal displacement, bar crossing, and overlapping is proposed in this study. Because the objective and constraint functions are linear expressions in terms of variables, the globally optimal structures can be obtained by using the proposed model. In addition, two necessary conditions for kinematic stability are proposed to speed up the computational efficiency and delete unnecessary nodes within consecutive tension bars. Finally, the effectiveness of the proposed NDF method and the necessary conditions for kinematic stability are studied on four truss topology optimization problems in two and three dimensions. [ABSTRACT FROM AUTHOR]

An analysis of changing patterns of the values of member forces in a scissors truss, depending on the position of connections of its lower chords to the upper chords, is performed. Exploring effective truss structure designs in terms of balanced combination of maximum strength and minimum weight is a sustainable approach to a more rational use of building materials and the development of green construction. This determines the relevance of this area of research. The analysis of configurations of the truss under study was performed using the parameterized Maxwell - Cremona diagram. Such diagram is a visually informative tool in presenting the calculation results and it fully reflects the relationship between the member forces and the parameters of the structure. The research process was performed using the MS Excel spreadsheet editor. This eventually developed into a software tool for finding effective scissors truss designs, which has full potential for further improvement and development. Thus, the functionality of the tool can be easily expanded to designing scissors trusses made of various structural materials, as well as with various crosssectional shapes of its elements. The proposed approach to the calculation of such structures can serve as a basis for parameterization of trusses with other types of web.

The next generation of large space infrastructure will require crucial advancements in current technology. Current methodologies focus on large deployable structures folded into cramped payload fairings or revolutionary assembly techniques requiring many moving components. Utilizing both in-space assembly and deployable concepts, a hybrid mixed assembly scheme was posed using smaller deployable units interspersed with rigid connecting elements to assemble these large architectures. The Built On-Orbit Robotically Assembled Gigatruss (BORG) structure allows for modularity in assembly and repair with the number of separate elements comprising the structure to be reduced, compared to strut-by-strut assembly. The following documents the process of constructing and running physical trials on a prototype BORG architecture. Additionally, a Semantic and Fiducial Aided Graph Simultaneous Localization and Mapping (SF-GraphSLAM) approach is taken to verify the relation of assembled and deployed truss elements to aid in error evaluation and state estimation. This technology demonstration stands as a proof of concept in verifying the viability of the BORG architecture as a method for large structure assembly. [ABSTRACT FROM AUTHOR]

The paper is focused on the numerical analysis of the stability and load bearing capacity of a flat steel truss. The structure is supported by elastic lateral braces. The translational and rotational brace stiffness are taken into account. The linear buckling analysis is performed for the beam and shell model of the truss. The nonlinear static analysis is conducted for the structure initial geometric imperfections. As a result, the buckling and limit load depending on brace stiffness has been obtained. The reactions in elastic braces are compared to stabilizing forces calculated on the basis of actual code requirements. [ABSTRACT FROM AUTHOR]

Excessive time-consuming has been a great problem when applying metaheuristic algorithms to the optimization of structures using direct analyses, including steel truss structures. In this work, a robust optimization method was proposed to solve this issue. In the proposed method, an efficient variant of the differential evolution algorithm (DE), which was proved to be powerful in searching optimum designs and converged quickly, was employed as the optimizer. An effective framework based on LightGBM classification models was developed to save lots of time-consuming direct analyses required for evaluating constraints. To enhance the performance of LightGBM models, an adaptive parameter, which can reflect the convergence speed of the population, was proposed to prevent the imbalanced classification problem in the training data. Two truss optimizations with continuous design variables were studied, including a 47-bar power line and a 113-bar planar bridge. The results proved that the proposed method yielded better optimum designs than DE/best/1 and EpDE. It also saved more than 60% of time-computing compared to DE/best/1, EpDE, and 2EpDE. Besides that, the proposed framework for using LightGBM models was compatible with metaheuristics having different convergence rates, including DE/best/1, EpDE, and 2EpDE. [ABSTRACT FROM AUTHOR]

This study demonstrates that two- and three-dimensional spatially graded, truss-based polymeric-material metamaterials can be designed for beneficial impact mitigation and energy absorption capabilities. Through a combination of numerical and experimental techniques, we highlight the broad property space of periodic viscoelastic trusses, realized using 3D printing via selective laser sintering. Extending beyond periodic designs, we investigate the impact response of spatially variant viscoelastic lattices in both two and three dimensions. Our result reveal that introducing spatial variations in lattice topology allows for redirecting of the impact trajectory, opening new opportunities for engineering and tailoring lightweight materials with target impact functionality. This is achieved through the combined selection of base material and metamaterial design.

Compared with natural wood, laminated veneer lumber has the characteristics of high strength, flexible specifications, excellent stability, and good economy. In order to study the bearing capacity of LVL trusses, the mechanical properties of LVL materials were tested. The static load test was carried out by using 3 pieces of LVL truss, and the load-deflection relationship, load-strain relationship, bearing capacity and failure mode of LVL trusses were studied. Based on the simplified joint analysis method, the metal plate connection and bolted truss were analyzed, and the bearing capacity calculation formula was developed. The results show that the upper chord instability is the main failure mode for large-span light LVL truss. A simplified formula for bearing capacity of LVL truss was proposed, and the predicted results were in good agreement with the experimental results. Finally, an application example of LVL truss engineering design and construction is briefly introduced. The research can provide technical support for the promotion and application of LVL truss of lightweight poplar wood. [ABSTRACT FROM AUTHOR]

This paper presents two hybrid optimization methods known as PSOHHO and DPSOHHO optimization algorithms. In the first method, using a number of formulae, the top populations are exchanged between the two algorithms and a new population is created and in the second method, we adopted the parallel optimization and optimized its performance. In this method, unlike other parallel methods, the population does not remain constant. With this ability, the strengths of an algorithm can be used to compensate for the weaknesses of the other algorithm. In these methods, no changes are made to the algorithms. The main goal is to use existing algorithms. These methods attain the optimal solution in the shortest time possible. Two algorithms of particle swarm optimization (PSO) and Harris Hawks's optimization (HHO) are used to present this method and two truss samples and CEC209 are considered to confirm the performance of this method. Based on the results, these methods have rapid convergence speed and acceptable results compared to other methods. [ABSTRACT FROM AUTHOR]

Compared with natural wood, laminated veneer lumber has the characteristics of high strength, flexible specifications, excellent stability, and good economy. In order to study the bearing capacity of LVL trusses, the mechanical properties of LVL materials were tested. The static load test was carried out by using 3 pieces of LVL truss, and the load-deflection relationship, load-strain relationship, bearing capacity and failure mode of LVL trusses were studied. Based on the simplified joint analysis method, the metal plate connection and bolted truss were analyzed, and the bearing capacity calculation formula was developed. The results show that the upper chord instability is the main failure mode for large-span light LVL truss. A simplified formula for bearing capacity of LVL truss was proposed, and the predicted results were in good agreement with the experimental results. Finally, an application example of LVL truss engineering design and construction is briefly introduced. The research can provide technical support for the promotion and application of LVL truss of lightweight poplar wood.

The present paper deals with the prediction of the fatigue life of a planar tubular truss, when geometrical parameters, material properties, and live loads are non-deterministic. A multi-level calculation uncertainty quantification framework code was designed to aggregate the finite element method and fatigue-induced sequential failures. Due to the incompleteness of the aleatory-type inputs, the maximum entropy principle was applied. Two sensitivity analyses were performed to report the most influencing factors. In terms of variance, the results suggest that the slope of the curve crack growth rate � stress intensity factor range is the most influencing factor related to fatigue life. Furthermore, due to the application of the entropy concept, the fatigue crack growth boundaries and fatigue crack semi-width boundaries obtained provide the most unbiased fatigue crack design mapping. These boundaries allow the designer to select the worst-case fatigue scenario, besides being able to predict the crack behavior at a required confidence level.

A composite box girder is a type of structural element that possesses strong torsional stiffness and resistance against flexural forces. A new category of bridge structure has been established: one that consists of concrete-filled steel tubes connected to composite slabs by steel trusses. In this study, an experimental and computational analysis of flexural loadings on four different types of composite box girders that are connected to concrete-filled steel tubes is presented. The specimens in this test are subjected to a concentrated load at the span's midpoint. The first model is a concrete-filled tube with no internal stiffeners and is used as a control specimen. The second model is a concrete-filled tube with double internal I-shaped stiffeners welded inside a steel tube. The third model features double T-shaped stiffeners, and the fourth model features stiffeners in the shape of a V. When compared with the control specimen, the results of the tests demonstrated that the Concrete-Filled Steel Tube (CFST) section equipped with internal stiffeners provided a better strength capacity and exhibited less deflection. The I- and the V-shaped stiffeners were found to be inferior to the T-shaped. The findings of the numerical analysis were in accordance with the results of the test. [ABSTRACT FROM AUTHOR]

In the construction of modern bridges, tower cranes are used for vertical transportation and hoisting. In erecting and removing tower cranes, a high degree of risk occurs. Thus, we evaluated the risk of using tower cranes in construction and proposed preventive measures. [ABSTRACT FROM AUTHOR]

This paper focuses on the use of truss topology optimization using an evolutionary approach to find optimized, additively manufactured components through a multi-objective formulation, keeping in mind application areas like 3D printing. Additive manufacturing plays a key role here, as the inherent complexity of most optimized truss structures would not allow for any different manufacturing techniques. The multi-optimization formulation consists of optimizing two conflicting objectives: minimization of structural compliance and minimization of heat flowing from the structure to its supports. A background on truss topology optimization, including a literature overview and the motivation behind the problem, is presented. The physical models and the optimization algorithms are explained and afterward, an example problem is solved and analyzed. [ABSTRACT FROM AUTHOR]

The present paper deals with the prediction of the fatigue life of a planar tubular truss, when geometrical parameters, material properties, and live loads are non-deterministic. A multi-level calculation uncertainty quantification framework code was designed to aggregate the finite element method and fatigue-induced sequential failures. Due to the incompleteness of the aleatory-type inputs, the maximum entropy principle was applied. Two sensitivity analyses were performed to report the most influencing factors. In terms of variance, the results suggest that the slope of the curve crack growth rate x stress intensity factor range is the most influencing factor related to fatigue life. Furthermore, due to the application of the entropy concept, the fatigue crack growth boundaries and fatigue crack semi-width boundaries obtained provide the most unbiased fatigue crack design mapping. These boundaries allow the designer to select the worst-case fatigue scenario, besides being able to predict the crack behavior at a required confidence level. [ABSTRACT FROM AUTHOR]

The next generation of large space infrastructure will require crucial advancements in current technology. Current methodologies focus on large deployable structures folded into cramped payload fairings or revolutionary assembly techniques requiring many moving components. Utilizing both in-space assembly and deployable concepts, a hybrid mixed assembly scheme was posed using smaller deployable units interspersed with rigid connecting elements to assemble these large architectures. The Built On-Orbit Robotically Assembled Gigatruss (BORG) structure allows for modularity in assembly and repair with the number of separate elements comprising the structure to be reduced, compared to strut-by-strut assembly. The following documents the process of constructing and running physical trials on a prototype BORG architecture. Additionally, a Semantic and Fiducial Aided Graph Simultaneous Localization and Mapping (SF-GraphSLAM) approach is taken to verify the relation of assembled and deployed truss elements to aid in error evaluation and state estimation. This technology demonstration stands as a proof of concept in verifying the viability of the BORG architecture as a method for large structure assembly.

In this article, the object of research is spatial framed systems, one of the most commonly used types of spatial structures. The main feature of the research is the expansion of proven design solutions to the area of large-span frames with rectangular plan with an aspect ratio of less than 1:2, which is an urgent research and practical task. In this regard, the main purpose of the research study is to establish a connection between the main parameters of the projected object (geometric characteristics, structural loads) and their metal intensity. The study was based on a number of research methods. We used the finite element method in the numerical study of the coating stability of rods loaded in the axial direction. The method of physical modeling helped in experimental studies of models and coatings of their elements. Finally, the method of optimal design, specifically the Nelder–Mead method, was used to find the basic shape of a structure with a long-span rectangular plan. Main results. First, the data from theoretical and experimental studies confirmed a decrease in the estimated length of the compressed elements by 5...25 % due to their partial pinching in the ball nodes-connectors. Secondly, we developed an optimal design algorithm of spatial frames with long-span rectangular plans with an aspect ratio of less than 1:2. It differs from the previously developed ones due to a clarification of the load-carrying ability of axially loaded rods from the stability condition and the project designer's advanced capabilities in terms of their shaping. It provides an opportunity to use clear correspondences at the trial design stage and to clarify the specific metal consumption to set the optimal geometric parameters of the projected structure. We found patterns that make it possible to design optimal material consumption flat and spatial structural forms of spatial frames on rectangular large-span plans with an aspect ratio of less than 1:2, while taking into account the refined bearing capacity of rods loaded in the axial direction. The results obtained make it possible to use a proven limited range of structural elements in the form of round-section rods and connecting elements (ball-and-socket plug-connectors).

The new Boca del Cerro Bridge is in southern Mexico at the exit of the Usumacinta River Canyon, in the city council of Tenosique in the state of Tabasco. A place of an extraordinary environmental value. This area is also a strategic crossing point, in which the actual Bridge over the Usumacinta River was built in 1950. It is a structure of extraordinary value, which is a milestone of the engineering of the time, with an upper arch of steel truss. The new Boca del Cerro Bridge has been designed, for the new Section 1 of the "Tren Maya" railway, parallel to the actual bridge. The solution adopted for the new bridge consists of a main span of double steel truss with double composite action (steel and concrete) and variable depth, that will be embedded in two lateral compensation spans of prestressed concrete. The new bridge has been designed in order to ensure a minimal "competition" and intrusion with the existing bridge and to enhance the beauty of the surrounding nature. The structural typology election has been conditioned by the advantages of its constructive process, that allows structure built‐up without riverbed support. To achieve this, the central span is planned to be erected by incremental cantilevers, carrying truss segments over the deck. [ABSTRACT FROM AUTHOR]

This study applied finite element analysis to a steel-concrete composite plate resting on the axial bar, using a four-node quadrilateral finite element for a steel-concrete composite plate combined with a truss element. Plate displacements and deformations were used to formulate the finite element method based on the first-order plate theory, also known as the Mindlin plate theory. The finite element analysis to combine steel-concrete composite plates and axial bars was implemented in MATLAB. Numerical examples were used in detail, showing a very small difference between the current study and the SAP2000 results. [ABSTRACT FROM AUTHOR]

The composite box girder is a structural element with high torsional stiffness and resistance against flexural loads. A new form of bridge construction is the Concrete-Filled Steel Tubes (CFSTs) linked to composite slabs by steel trusses. In this study, four different kinds of composite box girders linked to steel tubes filled with concrete were analyzed experimentally and numerically while being subjected to flexural loads. The specimens were evaluated when subjected to a focused load at the mid-span. The first model is a concrete-filled tube without stiffeners and was considered the control specimen, the second model is a concrete-filled tube with internal I–shaped stiffeners welded inside the steel tube, the third was filled with T-shaped stiffeners, and the fourth with V-shaped stiffeners. The test results showed that the CFST sections with interior stiffeners gave higher strength capacity and less deflection than the control specimen. The best shape of the stiffeners was the T-shape. The numerical analysis results were in accordance with the test results. [ABSTRACT FROM AUTHOR]