Truss Research Articles

Seismic Analysis of Large-span Steel Truss Structure Based on PKPM

In the construction industry, large-span steel truss structures are widely used. In order to test their seismic performance under different structures, select truss structures with better seismic performance, and use PKPM software to establish two cross-sectional triangular arch truss models with different web member arrangements, one cross-sectional trapezoidal arch truss model. Using the mode decomposition response spectrum method, simulate and analyze the displacement and stress changes of three sets of finite element calculation models under different load combinations during earthquakes. The results showed that all truss models meet seismic requirements. The change in the arrangement of the web members did not significantly improve the seismic performance of the cross-sectional triangular truss, the seismic performance of the cross-sectional trapezoidal arch truss was significantly better. The lower chord of the triangular arch truss support and the mid-span top chord are under compression, while the top chord is only compressed on one side and tensioned on the other side. The top chord of the trapezoidal arch truss is mainly under pressure.

Finite Element Analysis of Joint in Prefabricated Carbon Fiber Composite Truss

Carbon fiber composite truss, as an innovative structural form, has been widely used in the construction industry. However, the joint is serving as a crucial component of the truss structure construction. In order to improve the design level of the truss, this paper mainly studies the prefabricated carbon fiber composite truss joints. Firstly, the finite element analysis method is used to simulate the truss joint, and the stress nephogram under different geometric conditions is obtained. Then, the stress deformation mode and stress distribution mode are analyzed in depth. The calculation results are compared with similar steel pipe truss joints, and the accuracy of stress distribution is verified. Finally, the relationship between stress concentration area, stress concentration degree, maximum stress size and geometrical parameters of joint is revealed. Results in this paper can guide the design of this kind of truss structures, which can help develop more efficient and durable construction projects

Layout and cross-sectional size optimization of truss structures with mixed design variables based on gradient method

The object of the study was truss-type rod structures, which were investigated for the purpose of finding the optimal design solution in a mixed (continuous and discrete) space of variables. The parameters of the geometric scheme of the truss, as well as the dimensions of the cross-sections of its elements, were considered as design variables. The stated optimization problem is represented as a nonlinear programming task, in which the objective function and nonlinear constraints of the mathematical model are continuously differentiable functions of the design variables. The system of constraints includes strength and stability inequalities, formulated for the design cross-sections of the rod elements of the structure, which is subject to the effect of the design load combinations of the ultimate limit states. As a part of the system of constraints, the displacement constraints formulated for the specified structural nodes, which is subject to the action of design load combinations of the serviceability limit states, are considered. To solve the stated optimization problem, a method of the objective function gradient on the surface of active constraints was used, with the simultaneous elimination of residuals in the violated restrictions. For design variables, the variation of which must be performed according to a given set of possible discrete values, a discretization procedure for the optimal solution obtained in the continuous space of design variables is proposed. A comparison of the proposed optimization methodology with alternative metaheuristic methods and algorithms reported in the literature was performed. On the considered problem of parametric optimization of a 47-span tower structure, a design solution with a weight of 835,403 kg was obtained, which is 1.53...4.6 % better than the optimal solutions obtained by other authors

A Metamodel-Based Multi-Scale Reliability Analysis of FRP Truss Structures under Hybrid Uncertainties.

This study introduces a Radial Basis Function-Genetic Algorithm-Back Propagation-Importance Sampling (RBF-GA-BP-IS) algorithm for the multi-scale reliability analysis of Fiber-Reinforced Polymer (FRP) composite structures. The proposed method integrates the computationally powerful RBF neural network with GA, BP neural network and IS to efficiently calculate inner and outer optimization problems for reliability analysis with hybrid random and interval uncertainties. The investigation profoundly delves into incorporating both random and interval parameters in the reliability appraisal of FRP constructs, ensuring fluctuating parameters within designated boundaries are meticulously accounted for, thus augmenting analytic exactness. In application, the algorithm was subjected to diverse structural evaluations, including a seven-bar planar truss, an architectural space dome truss, and an intricate nonlinear truss bridge. Results demonstrate the algorithm's exceptional performance in terms of model invocation counts and accurate failure probability estimation. Specifically, within the seven-bar planar truss evaluation, the algorithm exhibited a deviation of 0.08% from the established failure probability benchmark.

Dynamic analysis of a pedestrian timber truss bridge at three construction stages

This article investigates the dynamic behaviour of a single span pedestrian timber truss bridge by in situ testing and numerical modelling. The in situ dynamic tests were performed at three different construction stages: (1) on only the truss structure, (2) on the finished bridge without the asphalt layer and (3) on the finished bridge with the asphalt layer. The objective is to better understand how the different parts of the bridge contribute to the overall dynamic properties. The experimental results show that the damping ratios increased significantly for the first lateral mode (from 1.0 to 3.8%) and the first torsional mode (from 1.2 to 3.5%) between stage 2 and stage 3 due to the asphalt layer. The damping ratio is around 1.6% for the first bending mode for the finished bridge. The experimental and numerical results indicate that the stiffness of the asphalt layer is important to consider at stage 3 (10 °C) for the first lateral and torsional mode, but not for the first bending mode. Finally, it was concluded that longitudinal springs must be applied at the pot bearings in order to get agreement with the experimental results at all the three stages.

The Performance of Bamboo Truss with Gapit Form Under Vertical Loads

The connection in bamboo construction is frequently the weakest point. This research discusses the performance of the gapit form on bamboo truss that effectively optimises the bamboo's inherent strength and can sustain vertical loads. Gapit is a connection form where a member is located between two members which also serves as a construction reinforcement. This truss optimizes the strength of whole bamboo with a total span of 4 meters and height of 2 meters. The gapit form applied at the top chord member, bracing member, and "V" support and column connections which are strengthen with bolts on the bamboo node. This research uses a quantitative method where data collection is taken through an experiment. To test the strength of the truss, a vertical hydraulic compression test was conducted. It was found that the truss can withstand a maximum load of up to 8.72 kN, with a truss decline of 7.27 cm, and a shift of 2 cm. As a result, the use of the gapit form on the truss is considered effective in withstanding large vertical loads.

Research on 18th-Century Building Structures in Terms of Static Scheme Changes.

The evaluation of the technical condition of historic buildings that have operated for several hundred years is a complicated issue. Even buildings that are in very poor condition must be checked and assessed in terms of their further repair, strengthening, or compliance with conditions that allow the facility to be safely operated. Most 18th-century buildings have not survived to this day retaining their original arrangements and structural elements. Renovations and repair work in the past were often carried out using materials of uncertain quality, with repair work of different qualities and without detailed analysis or methodology, based only on the experience of the former builders. In historic structures, the character of the work of individual structural elements has often changed due to significant material degradation, the poor quality of repair work, or the loss of adequate support. When load transfers change, internal forces are redistributed, and, as a result, the static scheme changes. This article presents an overview of identified defects affecting the change in static schemes in historical building structures built in the 18th century, using the example of a historic building with a large number of aforementioned defects. The process of assessing the technical condition of the facility is presented, in which non-destructive testing (NDT) methods were used. Detailed computational analyses were carried out for the wooden roof truss structure, which had partially lost its support.

Graph-based representation of history-dependent material response in the Data-Driven Computational Mechanics framework

This work develops an extension of the Data-Driven Computational Mechanics approach introduced by Kirchdoerfer and Ortiz (2016) to history-dependent behaviour. The material database is replaced by a material directed graph, where vertices represent strain–stress pairs and arcs encode thermomechanically admissible transitions between them. A graph search algorithm is used to select local material databases representative of the incremental material behaviour. This study thus gives the mathematical tools for a structured data-driven representation of the material behaviour, designed to minimise the increase of the problem dimensionality. The performances of the proposed approach applied to elastoplasticity are studied on a single-element structure and a larger truss structure. A two-step solver is proposed to address numerical accuracy issues in the latter case.

Load-bearing capacity of a truss girder during assembly

Load-bearing capacity of a truss girder during assembly

Load-bearing capacity of a truss girder during assembly

Load-bearing capacity of a truss girder during assembly

On the use of mechanics-informed models to structural engineering systems: Application of graph neural networks for structural analysis

This paper investigates the application of mechanics-informed artificial intelligence to civil structural systems. Structural analysis is a traditional practice that involves engineers to solve different real-life problems. Several approaches can be used for this task, going from “by hand” computation to the recent advanced finite element method. However, when structures become complex, the success of the analysis can be complicated, often requiring high computational efforts and time. To tackle this challenge, traditional high-demanding methods can be supported by new technologies, such as machine-learning tools. This new paradigm aims to solve structural problems by defining the desired output after directly elaborating input data. One of the current limitations is that often the physics behind the problem is ignored. To solve this issue, resolution models can combine empirical data and available mechanics prior knowledge to improve the predictive performance involving physical mechanisms. In this paper, a method to develop a Mechanics-Informed Surrogate Model (MISM) on structural systems is proposed, for which input structured data are used to enrich the informative content of mechanics systems. Then, Graph Neural Networks (GNNs) are explored, as a method capable of properly representing and embedding knowledge about a structural system, such as truss structures. The main advantage of the proposed approach is to provide an alternative way to the usual black-box machine-learning-based models. In fact, in the proposed MISM, the mechanics of the structural system plays the key role in the surrogate model definition, in order to obtain physically based outputs for the investigated problem. For the case at hand, MISMs are developed and employed to learn the deformations map of the system, starting from the knowledge of the structural features. The proposed approach is applied to bi-dimensional and tri-dimensional truss structures and the results indicate that the proposed solution performs better than standard surrogate models.

Improved Sine-cosine Algorithm for the Optimization Design of Truss Structures

The sine cosine algorithm (SCA) is a new meta-heuristic algorithm. It has been proven to be very competitive compared with other meta-heuristic algorithms and has attracted significant attention from researchers in different fields. At present, there is no research on the application of SCA in the truss structure. In order to solve the truss optimization problem, the following improvements are made to SCA in this paper. Firstly, a non-linear conversion parameter is set to replace the linear conversion parameter, so that the exploration area is better in line with the characteristics of the actual optimization situation. Secondly, the Lévy flight is employed to enhance the algorithm's global search ability. Thirdly, a novel elite guidance strategy taking advantage of memory data is proposed to strengthen the local search ability. Finally, a greedy selection strategy is adopted for the selection of the candidate. Combining the finite element method, we apply ISCA to optimize the size, shape and topology of truss structures. The examples show that ISCA can use less calculation time, get better results, and also better stability. So, the ISCA is effective to solve the size, shape and topology optimization problems of truss structures.

Static behavior of ribbed folded plate roof under vertical uniform load—Experimental study and meshfree method analysis

SummaryFolded plate roofs are widely used in building roofs due to their light weight and high stiffness. However, traditional folded plate roofs are often limited in application due to insufficient stiffness under the current trend of pursuing larger‐span roofs. Ribbed folded plate roofs can effectively solve this problem because ribs not only increase the stiffness of the roof and reduce stress concentration, but they are also easy to be formed into various shapes to meet different needs for buildings. Therefore, the detailed analysis was carried out on a reinforced concrete ribbed folded plate roof (RCRFR) under the vertical uniform load to investigate its static behavior. The bearing capacity, failure mode, load–displacement relationship, and strain variation were obtained through the test. Additionally, based on the finite element (FE) method, not only a comparison was conducted between RCRFR and reinforced concrete ribless folded plate roof (RCLFR), but the influence of material nonlinearity and geometric nonlinearity on the structure was also investigated. Moreover, the bending characteristics of RCRFR under design load were analyzed based on the reproducing kernel particle method. The experimental results showed that this structure had good mechanical properties within the design load. In the overload stage, the concrete on the underside of the structure was severely damaged. Furthermore, the yielding of the ribbed plate's reinforcing bars caused the increased vertical deformation difference between the ribbed plate and the top chord, and the ribbed plate and the central ridge beam. Eventually, the failure of the anchorage of the ribbed plate's reinforcing bars anchored in the central ridge beam and the top chord led to the loss of structural load‐bearing capacity. The FE analysis results demonstrated that ribs enhance the stiffness of the structure, with material nonlinearity having the primary impact and geometric nonlinearity exerting a secondary effect. The meshfree method analysis was in concordance with the experimental results as well as those of the FE analysis.

Numerical analysis of 3d truss bridge using ANSYS

Trusses are typically lighter and more cost-effective than alternative structural support systems and are used in a variety of structures including vehicle frames, mechanical equipment, buildings, bridges, and towers. A truss structure takes advantage of the inherent geometric stability of the triangle to evenly distribute weight and to handle changing tension and compression. This project deals with the analysis of a 3D truss bridge which is proposed to be constructed connecting the two platforms of the Tripunithura railway station, with three different deck materials glass fibre reinforced concrete (GFRC), concrete and steel. Analysis and design of the proposed structure is carried out using ANSYS (Workbench) 2022 R2 software. ANSYS is an analysing software that is used for mechanical product designs and civil structure designs. It uses computer based numerical techniques to solve problems. This software helps to engineer and design complex, highly nonlinear and large models. It enables to design and manage 3D structures in steel, concrete and glass fibre reinforced concrete (GFRC). Structural performance of 3D truss bridges with three different deck material in terms of axial force, shear stress and deformation are compared in order to find which combination of materials will give better performances. Dynamic analysis is performed to examine the frequency and modes of vibrations caused by the movement of trains.

Multi-objective optimization of truss structure using multi-agent reinforcement learning and graph representation

This paper presents a novel method for multi-objective optimization of truss design utilizing multi-agent reinforcement learning and graph representation. The agents are trained to modify solutions to increase the hypervolume and spread the distribution of the non-dominated solutions. This iterative modification is modeled as a Markov game where multiple agents interact with the environment by changing the state of the environment, i.e., the solution and the current non-dominated solutions. Agents observe data representations of the state, modify each solution in the current non-dominated solutions, and receive their reward based on the improvement of the current non-dominated solutions. Each agent is modeled by the multi-agent deep deterministic gradient consisting of a policy function that predicts actions from its observation data and a value function that estimates rewards from the observation data, its action, and the actions of the other agents. The non-dominated solutions are represented as graph data and observed by the agents as the observation data through graph representation. The proposed method is applied to three multi-objective optimization problems: (1) a simple mathematical problem, (2) a 10-bar truss problem to minimize the structural volume and the displacement, and (3) trade-off designs of trusses to minimize the structural volume and bring the shape closer to the target shape. These numerical examples show the versatility of the trained agents to obtain superior solutions in practical structural optimization problems, compared to a conventional method.

Study on the mechanism and performance of 3D-printed PLA/epoxy composite for stab resistance

PurposeStab-resistant body armor (SRBA) is used to protect the body from sharp knives. However, most SRBA materials currently have the disadvantages of large weight and thickness. This paper aims to prepare lightweight and high-performance SRBA by 3D printing truss structure and resin-filling method.Design/methodology/approachThe stab resistance truss structure was prepared by the fused deposition modeling method, and the composite structure was formed after filling with resin for dynamic and quasi-static stab tests. The optimized structural plate can meet the standard GA68-2019. Digital image correlation technology was used to analyze the local strain changes during puncture. The puncture failure mode was summarized by the final failure morphologies. The explicit dynamics module in ANSYS Workbench was used to analyze the design of the overlapped structure stab resistance process in this paper.FindingsThe stab resistance performance of the 3D-printed structural plate is affected by the internal filling pattern. The stab resistance performance of 3D-printed structural parts was significantly improved after resin filling. The 50%-diamond-PLA-epoxy, with a thickness of only 5 mm was able to meet the stab resistance standard. Resins are used to increase the strength and hardness of the material but also to increase crack propagation and reduce the toughness of the material. The overlapping semicircular structure was inspired by the exoskeleton structure of the demon iron beetle, which improved the stab resistance between gaps. The truss structure can effectively disperse stress for toughening. The filled resin was reinforced by absorbing impact energy.Originality/valueThe 3D-printed resin-filled truss structure can be used to prepare high-performance stab resistance structural plates, which balance the toughness and strength of the overall structure and ultimately reduce the thickness and weight of the SRBA.

Nonlinear dynamic response analysis of a hybrid concrete‐filled steel tubular truss lightweight bridge under strong earthquakes

AbstractConcrete‐filled steel tubular (CFST) trusses have seen recent development and application in bridges found in mountainous regions with deep valleys, and especially in seismic zones. In this study, a hybrid CFST truss lightweight bridge was selected as the research object. This bridge is composited of CFST composite truss girders (superstructure) and CFST lattice piers (substructure). Two different finite element models (FEM) for nonlinear seismic response analysis, one is detailed model and the other is simplified model, were established. By comparing with the detailed model, the results of the shaking table test as well as the real bridge test, the simplified model was found to be accurate. Considering the CFST columns' edge strain, the most unfavorable input direction of horizontal ground motion was perpendicular to the connection line of the bearings at both ends of the main girder. Also, the simultaneous influence of vertical ground motion and horizontal ground motion needs to be taken into consideration. By increasing the intensity of input ground motion, the yielding order of CFST lattice piers and its effect on the seismic response were also discussed. Results indicated that the bridge was in the elastic stage for the designed seismic ground motion. After the CFST lattice piers reached the plastic stage, the displacement and in‐plane bending moment had larger amplification coefficients compared to the increase coefficient of the input ground motion, while had a much smaller axial force amplification coefficient. Moreover, the in‐plane bending moment had a larger amplification coefficient in high piers compared to short piers.

Stock Optimization of Naturally Curved Wood Logs on Freeform Truss Structures

This paper presents an optimization method for incorporating discarded naturally curved wood logs onto a freeform gridshell with a predefined topology. Though still little explored, the research field of reusing structural elements is experiencing increasing attention owing to its significant potential to reduce the environmental impact of building design. However, several constraints must be considered as the optimal structure depends on stock availability and the corresponding geometry and material properties of that given stock. Therefore, the focus is on determining the best configuration of stock elements considering the defined design objectives and constraints. The proposed method is a top-down approach, as the global topology of the structure is predetermined. Multi- objective optimization is conducted using the Strength Pareto Evolutionary Algorithm 2 (SPEA2) and a modified genetic algorithm with permutation encoding in the form of ordered crossover and scramble mutation. Furthermore, this paper introduces a Team-Based Repair (TBR) algorithm that increases the likelihood of each solution being valid for analysis. The performance of the optimization method is demonstrated on a curved gridshell structure, and the effect of the different design objectives and stock sizes on the final design is analyzed and discussed.

A Comparative Analysis of Optimization Algorithms for Finite Element Model Updating on Numerical and Experimental Benchmarks

Finite Element Model Updating (FEMU) is a common approach to model-based Non-Destructive Evaluation (NDE) and Structural Health Monitoring (SHM) of civil structures and infrastructures. Its application can be further utilized to produce effective digital twins of a permanently monitored structure. The FEMU concept, simple yet effective, involves calibrating and/or updating a numerical model based on the recorded dynamic response of the target system. This enables to indirectly estimate its material parameters, thus providing insight into its mass and stiffness distribution. In turn, this can be used to localize structural changes that may be induced by damage occurrence. However, several algorithms exist in the scientific literature for FEMU purposes. This study benchmarks three well-established global optimization techniques—namely, Generalized Pattern Search, Simulated Annealing, and a Genetic Algorithm application—against a proposed Bayesian sampling optimization algorithm. Although Bayesian optimization is a powerful yet efficient global optimization technique, especially suitable for expensive functions, it is seldom applied to model updating problems. The comparison is performed on numerical and experimental datasets based on one metallic truss structure built in the facilities of Cranfield University. The Bayesian sampling procedure showed high computational accuracy and efficiency, with a runtime of approximately half that of the alternative optimization strategies.

Finite Element-Based Optimization of Cross-Section Area on 2D Truss Structure with 10-members and 12-members Using Nonlinear Programming Method

Designing a structure requires good planning to obtain optimal results. Some things that need to be considered in designing structures are the materials used, the dimensions of the structure, and others. By optimizing the dimensions of the structure, the use of materials can be minimized so that production costs can be reduced. The experiment requires additional cost and time. Therefore, finite element software can be used to design the structure optimally in compliance with the constraints set according to the requirements. Previous studies have carried out cross-section area optimization of structures with maximum allowable stress limits. In this research, the optimization of 2D truss cross-section area with maximum volume constraint is developed using MATLAB software with fmincon function. The structure is modelled in 2 shapes: a 2D truss with ten members and a 2D truss with twelve members. The optimum area is obtained from the simulation results, which are almost the same in both structures, while the lower stress value is obtained in the ten-member 2D truss structure. The maximum stress (tensile stress) on the 12-member 2D truss occurs on element 12 at 3484.28 psi, and then the minimum stress (compressive stress) occurs on elements 3, 4, 8, and 9 at -3472.10 psi. The maximum stress (tensile stress) on the 10-member 2D truss structure occurs in elements 1 and 9 at 3472.10 psi, and the minimum stress (compressive stress) occurs in element four at -3479.77 psi.