Truss Research Articles

Recent Development on Doubler or Collar Plate Reinforced Square Hollow Section Joints under Brace Axial Load

Tubular joints are crucial structural components in steel tubular truss structure. Doubler or collar plate reinforcement has gained popularity in strengthening square hollow section (SHS) joints on the chord. But the existing design rules for the reinforced tubular joints require improvement. This paper reviews literature on SHS joints strengthened by doubler or collar plate. Key geometrical parameters, structural behaviour and failure modes of reinforced SHS joints reported in literature were discussed. Design methods in specifications and literature were evaluated by comparing the design values with experimental results. It was shown that the approach using linear fitting coefficients obtained by key parameters is able to provide a more accurate prediction. The SHS joint strengthening process with doubler plate or collar plate is discussed, highlighting some construction restrains. Finally, the trend and development direction of this field are proposed.

Mixed Finite Element Formulation in Nonlinear Geometrical Analysis of Space Trusses and Application to Trusses With Member Length Imperfection

Abstract Space trusses usually have a significant number of elements. As a result, it is inevitable that some elements have imperfections. In this study, the authors proposed a mixed finite element method for nonlinear geometrical analysis of space trusses. The post-buckling behavior of space trusses with length imperfections was predicted using a code list written in the programming software. The numerical results indicate that when the length imperfection approaches zero, the results converge to those obtained in studies on standard trusses. A second approach based on the displacement model is also proposed, in which the Lagrange multiplier method is used to deal with the member length imperfection. The results show that the two approaches proposed by the authors are effective, in which the mix formulation based on the finite element model is superior to that based on the displacement model. These results verify the accuracy of the method. Based on the proposed method, the effects of imperfections in the element layers on the truss were studied. The results show that the imperfections in the top two element layers have the maximum influence on the limit load value, whereas the remaining layers have a negligible influence. The combination of the imperfect lengths of these two layers of elements can produce results in which the limit load value is much larger than in the case of a perfect system. Based on the obtained results, it is possible to provide a solution for improving the overall stability of truss structures by creating reasonable imperfections.

Application of a novel metaheuristic algorithm inspired by connected banking system in truss size and layout optimum design problems and optimization problems

Optimum design of truss structures can be a challenging and difficult field of study specially if an optimum design problem is comprised of continuous and discrete decision variables such as in truss size and layout optimization problems. Usually metaheuristic approaches are selected to solve these kind of problems and there are many different metaheuristic methods that have been used in dealing with truss optimization problems, which provide optimum solutions for those problems. However, among these various proposed metaheuristics, it is very seldom to face and find a method that is based on technologies such as computer networks. This paper aims to utilize a metaheuristic algorithm which is based on some principals of connected banking systems, which is called the Connected Banking System Optimizer(CBSO) algorithm. The performance of the CBSO is tested against three benchmark truss size/layout optimum design problems namely 15, 18 and 25 bar truss structures. Besides the truss size/layout problems, CEC-BC-2017 test functions with ten dimensions and also three other constrained optimum design problems are also investigated to examine the performance of the CBSO in dealing with these standard unconstrained and constrained test functions. The results of the CBSO optimum designs are presented and compared with some of the available studies in the literature. Statistical analyses are done to have a fair evaluation of the CBSO algorithm’s efficiency and its ability in dealing with the benchmark truss size/layout optimization problems. The CBSO outperforms its rivals and presents lighter weight truss structures. There is no need for configuration of extra parameters in the CBSO algorithm when solving the examined benchmark truss structures, which makes it a robust parameter-free optimization algorithm.

Enhanced Subspace Iteration Technique for Probabilistic Modal Analysis of Statically Indeterminate Structures

In structural stochastic dynamic analysis, the consideration of the randomness in the physical parameters of the structure necessitates the establishment of numerous stochastic finite element models and the subsequent computation of their corresponding vibration modes. When the complete analysis is applied to calculate the vibration modes for each sample of the stochastic finite element model, a substantial computational expense is incurred. To enhance computational efficiency, this work presents an extended subspace iteration method aimed at rapidly determining the vibration modal parameters of statically indeterminate structures. The essence of this proposed method revolves around efficiently constructing reduced basis vectors during the subspace iteration process, utilizing flexibility disassembly perturbation and the Krylov subspace. This extended subspace iteration method proves particularly advantageous for the modal analysis of finite element models that incorporate a multitude of random variables. The proposed modal random analysis method has been validated using both a truss structure and a beam structure. The results demonstrate that the proposed method achieves substantial savings in computational time. Specifically, for the truss structure, the calculation time of the proposed method is approximately 1.2% and 65% of that required by the comprehensive analysis method and the combined approximation method, respectively. For the beam structure, on average, the computational time of the proposed method is roughly 2.1% of a full analysis and approximately 48.2% of the Ritz vector method’s time requirement. Compared to existing stochastic modal analysis algorithms, the proposed method offers improved computational accuracy and efficiency, particularly in scenarios involving high-discreteness random analyses.

Mechanical carbon emission assessment during prefabricated building deconstruction based on BIM and multi-objective optimization

Machinery operation is a major source of carbon emissions in building deconstruction. Early intervention through Design for Deconstruction (DfD) is crucial for emission reduction, yet the factors influencing these emissions are underexplored. This study integrates parametric BIM with multi-objective optimization (MOO) to assess mechanical carbon emissions in deconstruction. Using the Octopus solver in Grasshopper for Rhino, the study analyzes independent variables—possible working hours (PWH), vertical speed (VS), and horizontal speed (HS)—and dependent variables—minimum mechanical carbon emissions (MCE (min)), minimum deconstruction period (DP (min)), and maximum working efficiency (WE (max)). A lightweight steel roof truss structure is analyzed, comparing real-world deconstruction with optimized DfD schemes. Sensitivity analysis for BIM-MOO optimized results reveal that: (1) Adjusting PWH, VS, and HS significantly affects WE and DP, though with limited impact on carbon emissions; (2) VS influences WE and DP more than HS; (3) Limiting DP is essential for balancing WE, DP, and MCE, with WE adjusted to 20–60% and modifications to PWH and VS achieving balanced management. This study underscores the importance of early design and real-time adjustments for efficient, low-emission deconstruction, supporting the advancement of green building practices.

Construction error control method of large-span spatial structures based on digital twin

In the process of construction of large-span spatial structures, there are many control elements, which need to carry on the dual control of internal force and shape. The traditional control method cannot measure the construction deviation completely and accurately, and there is a lag in information feedback. In this paper, spatio-temporal information is integrated into digital twin and a construction error control method is proposed for large-span spatial structures. By analyzing the fusion mechanism of spatio-temporal information and digital twin, a closed-loop control system for structural errors before, during and after construction is formed. Driven by the control architecture, the method of structure simulation analysis and real-time monitoring during construction is proposed, and the functional relationship between cable force and cable length is established. Based on point cloud data, construction error optimization detection method is proposed for structure formation state. The nonlinear relation between elevation change rate and cable force deviation is formed and the control measures of formation state error are obtained. The experimental model of cable truss structure is taken as an example to apply and verify the theoretical method. The construction error control twin platform is formed in the experiment. Driven by the platform, the twinning analysis and real-time monitoring of the construction process are carried out to control the error of the structure formation. The results show that this method integrates spatio-temporal information into digital twin to realize data integration processing. The optimized error detection method can save 30% time cost and effectively control the construction error within 3%. The integration of spatio-temporal information and digital twin provides theoretical and algorithm support for the intelligent management and control of large-span spatial structure construction.

Nonlinear flutter in a wind-excited double-deck truss girder bridge: experimental investigation and modeling approach

Nonlinear flutter in a wind-excited double-deck truss girder bridge: experimental investigation and modeling approach

On a minimization problem of the maximum generalized eigenvalue: properties and algorithms

AbstractWe study properties and algorithms of a minimization problem of the maximum generalized eigenvalue of symmetric-matrix-valued affine functions, which is nonsmooth and quasiconvex, and has application to eigenfrequency optimization of truss structures. We derive an explicit formula of the Clarke subdifferential of the maximum generalized eigenvalue and prove the maximum generalized eigenvalue is a pseudoconvex function, which is a subclass of a quasiconvex function, under suitable assumptions. Then, we consider smoothing methods to solve the problem. We introduce a smooth approximation of the maximum generalized eigenvalue and prove the convergence rate of the smoothing projected gradient method to a global optimal solution in the considered problem. Also, some heuristic techniques to reduce the computational costs, acceleration and inexact smoothing, are proposed and evaluated by numerical experiments.

Experimental study and numerical analysis of a novel serrated-and-plate truss structure

High-speed rail station has extensive span and height, making daylighting a challenge. This paper proposes the serrated-and-plate truss structure (SPTS) to improve station daylighting. SPTS combines a serrated truss structure (STS) for daylighting and a plate truss structure (PTS) for lateral stability and deformation resistance. A downscaled SPTS with support-loading system is designed and built to test mechanical properties. It has 264 stress and 19 displacement measuring points, tested under four vertical and two horizontal load cases. Maximal stress and displacement are 150.7 MPa and 5.07 mm, with peak chord axial force and column base bending moment of 13.5 kN and 663.7 kN mm. Simulated and measured results match well, confirming the numerical method's accuracy. Thermal effects of SPTS are studied via conventical and extreme thermal analyses, with stress and displacement well below limits. Seismic spectrum and time-history analyses indicate SPTS stress and deformation at 63.9 % and 68.3 % of limits. Comparative analysis across 64 load cases reveal that STS is significantly less stable and resistant to deformation than SPTS, validating PTS's boundary constraint effects. Experimental and numerical studies confirm SPTS's engineering applicability and provide valuable references for similar truss structure research.

Improved Monte Carlo tree search formulation with multiple root nodes for discrete sizing optimization of truss structures

This article proposes a novel reinforcement learning algorithm using an improved Monte Carlo tree search (IMCTS) formulation for the discrete optimum design of truss structures. IMCTS with multiple root nodes includes the update process, best reward, accelerating technique and terminal condition. The update process means that once a final solution is found, it is used as the initial solution for the next search tree. The best reward is used in the backpropagation step. The accelerating technique is introduced by decreasing the width of the search tree and reducing the maximum number of iterations. The agent is trained to minimize the total structural weight under various constraints until the terminal condition is satisfied. The optimal solution is the minimum value of all solutions found by the search trees. Numerical examples show that the agent can find the optimal solution with low computational cost, stably produces an optimal design, and is suitable for multi-objective structural optimization and large-scale structures.

Ride comfort assessment of road vehicles on a long-span truss girder suspension bridge under crosswinds

The precise identification of the aerodynamic loads on vehicles is a fundamental concern in assessing the ride comfort of vehicles crossing long-span bridges in the presence of strong crosswinds. However, the consideration of aerodynamic interference between vehicles and truss girder bridges is limited in existing studies. Furthermore, in practical engineering, wind barriers are commonly installed to enhance the ride comfort of vehicles crossing long-span bridges, but previous studies have primarily focused on the impact of wind barriers on the aerodynamic coefficients and dynamic responses of vehicles. This paper focuses on the aerodynamic interaction between trucks and truss girder bridges, through wind tunnel testing. The aerodynamic coefficients of the vehicle with three different ventilation ratios and four different heights of wind barriers were obtained. The dynamic response of road vehicles on a truss girder suspension bridge with a main span of 965 m was numerically calculated using the coupled analysis of wind-vehicle-bridge system and measured aerodynamic coefficients considering aerodynamic interference. On this basis, the comfort of road vehicles was investigated with different section types of the girder and different wind barrier parameters, and it was evaluated accordance with the overall vibration total value (OVTV) recommended in the ISO 2631–1. It is found that the aerodynamic coefficients of road vehicles are sensitive to the type of wind barrier. Wind barriers can reduce the road vehicle’s aerodynamic loads at high wind yaw angles. Wind barriers can also improve the ride comfort of road vehicles on the long-span truss girder suspension bridge.

Seismic resistance analysis and optimization of gymnasium truss structure

The gymnasium is mainly composed of truss structure, with a large span, and requires high seismic performance. To ensure greater stability of the truss structure, modal analysis was conducted on the mechanical model, yielding the natural frequencies and modal shapes. In order to improve the seismic performance, BRB rods were added to the support points, and the frame structure was reinforced with diagonal braces. Through modal verification, it can be seen that the stiffness of the truss structure was significantly improved. The internal forces of the truss were simulated under the El Centro and Taft seismic wave conditions. The results show that the optimized structure can significantly reduce the internal forces and improve the overall seismic performance. The fundamental natural period of the reinforced structure is less than that of the unreinforced structure, and the stiffness of the reinforced steel structure increases, making it more sensitive to vertical seismic motion.

Vision-based displacement monitoring for the integral lifting of a large-span spatial truss structure

Vision-based displacement monitoring for the integral lifting of a large-span spatial truss structure

Global Sensitivity Analysis and Surrogate Models for Evaluation of Limit States in Steel Truss Structures

This article presents the global sensitivity analysis of the serviceability limit state of a steel truss using Monte Carlo simulations. The focus is on the probabilistic assessment of deflection, with failure probability defined as the likelihood of exceeding the deflection limit. Deflection is computed using the beam finite element method. A surrogate model is introduced to reduce computational costs. By integrating the surrogate and original models, significant CPU cost reductions are achieved. Furthermore, classical Sobol sensitivity analysis is used to examine the model outputs and analyze the significance of member loading and stiffness on the deflection. This study advances the use of surrogate models in global sensitivity analysis, enhancing computational efficiency and the understanding of interactions between input variables in the reliability assessment of steel truss structures.

Improved krill swarm algorithm and its application in structural optimization

This paper improves and perfects the standard Krill herd algorithm (KH), which has the defects of slow convergence speed, insufficient calculation accuracy and easy to fall into local optimal solution for complex problems. An improved Krill herd algorithm (SDEKH) integrating improved differential evolution operator and S-type adaptive inertia weight is proposed. SDEKH, KH and other intelligent algorithms are compared and tested through a variety of standard test functions to verify the excellent performance of SDEKH; SDEKH is used to optimize the design of truss structure. By comparing the optimization results with other methods, it is verified that the optimization efficiency and accuracy of SDEKH are improved, which provides a more efficient and accurate method for the optimization design of engineering structures.

Research on the Gradual Change Model of Vibration Characteristics of Spatial Steel Truss Structures Under Fatigue Loading

Research on the Gradual Change Model of Vibration Characteristics of Spatial Steel Truss Structures Under Fatigue Loading

Efficient 3D robotic mapping and navigation method in complex construction environments

AbstractRecent advancements in construction robotics have significantly transformed the construction industry by delivering safer and more efficient solutions for handling complex and hazardous tasks. Despite these innovations, ensuring safe robotic navigation in intricate indoor construction environments, such as attics, remains a significant challenge. This study introduces a robust 3‐dimensional (3D) robotic mapping and navigation method specifically tailored for these environments. Utilizing light detection and ranging, simultaneous localization and mapping, and neural networks, this method generates precise 3D maps. It also combines grid‐based pathfinding with deep reinforcement learning to enhance navigation and obstacle avoidance in dynamic and complex construction settings. An evaluation conducted in a simulated attic environment—characterized by various truss structures and continuously changing obstacles—affirms the method's efficacy. Compared to established benchmarks, this method not only achieves over 95% mapping accuracy but also improves navigation accuracy by 10% and boosts both efficiency and safety margins by over 30%.

МОДЕЛЮВАННЯ ТА ОПТИМІЗАЦІЯ РЕЖИМУ ТЕРМООБРОБКИ ТРУБЧАСТИХ ЕЛЕМЕНТІВ ФЕРМЕННИХ КОНСТРУКЦІЙ ЛІТАЛЬНИХ АПАРАТІВ З ВУГЛЕПЛАСТИКУ

The article analyzes the current state of development of dimensionally stable tubular elements (TE) and technological problems arising during their production. It is shown that along with empirical methods of studying the influence of various technological schemes on the dimensional stability of tubular elements, it is useful to use the optimal temperature-time mode for heat treatment and, based on it, select the optimal technological scheme. Modeling and determination of the optimal mode of heat treatment of tubular elements were performed. The study of the TE heat treatment mode was carried out in two stages, first by methods of mathematical modeling and optimization, and then by empirical enumeration of various technological schemes. At the first stage, the material properties, which are parameters of the mathematical model, were studied, and the optimal curing modes were calculated. At the second stage, the calculated optimal curing modes were supplemented with various technological methods that cannot be mathematically modeled, and a study was carried out on the influence of the resulting combined heat treatment mode on the geometric characteristics and dimensional stability of carbon fiber TE. The mathematical model of the process of heat treatment and curing of TE in a heat chamber, when heated by a heating air flow, is a system of differential equations: thermal conductivity and curing kinetics. A mathematical model of the process of heat treatment of tubular elements manufactured by the winding method is proposed, the ways of optimizing the curing mode of carbon fiber TE are shown. A numerical calculation of temperature-conversion fields during curing and calculation of optimal curing modes of tubular elements are performed taking into account various process schemes. The values of heat capacity C and thermal conductivity l are calculated depending on the temperature T, the degree of curing b and the filling coefficient g, Безфітингова ферма з вуглепластику Безфітингова ферма з вуглепластику Безфітингова ферма з вуглепластику the power of heat release W and the thermal effect of the curing reaction Q of carbon fiber. Optimum curing modes for a plate made of composite polymer material are obtained, calculated from the data obtained as a result of studying material samples. Temperature-time curing modes are obtained, which are optimized for different thicknesses of the studied material. The statistical hypothesis about the significance of the influence of the process flow chart and reinforcement pattern on the wall thickness of a tubular element and its compressive strength was proved by the dispersion analysis method. The influence of process flow charts and heat treatment modes on the geometric and mechanical characteristics of carbon fiber tubular elements of aircraft truss structures was studied. The statistical hypothesis about the significance of the influence of the process flow chart and reinforcement pattern on the deviation of the wall thickness of tubular elements and their strength characteristics was tested. The significance of the influence of process flow charts with different heat treatment modes on the average wall thickness of a carbon fiber tubular element was statistically proven.

A novel iterative algorithm for nonlinear inelastic dynamic analysis of truss structures; MCB-Spline+Sp time integration method

The focus of this work is on the development of a novel algorithm for the nonlinear dynamic analysis of structures. In the sake of a general and easy-to-implement solution method, the tangential stiffness matrix is calculated by combining the Cauchy-Riemann equations derived from the differentiation of complex functions and using the nodal displacement perturbation vector. An implicit direct time integration method based on a cubic B-Spline is integrated with the incremental-iterative method using a quadrature rule based on the interpolation of spline functions, which is referred to as the MCB-Spline+Sp time integration method. A step-by-step algorithm for developing a computer code to implement this method is provided. The effectiveness of the proposed approach is evaluated through several nonlinear time history analyses, which demonstrate its accuracy and efficiency by observing less computational efforts and fast convergence rate. Moreover, a comparison is made between the developed method and well-established techniques such as the Newmark and Standard-Bathe time integration methods in combination with the iterative Newton-Raphson method.

Structural Evaluation on the Floating Production Storage and Offloading Large Flow Gas Processing Module Based on FEM Analysis

The floating hoisting of floating production storage and offloading (FPSO) production modules introduces substantial challenges due to the propensity for excessive deformation within the typical tubular truss structures during operations. This research proposes a temporary reinforcement scheme, leveraging finite element method simulations under wind, wave, and current loads, to mitigate deformation concerns. Utilizing DNV GeniE software, this study establishes a finite element model, simulating the floating lifting process and conducting a comparative analysis between pre- and post-reinforcement scenarios. The results demonstrate a significant reduction in maximum stress and deformation, substantiating the efficacy of the reinforcement strategy and underscoring the safety and reliability of such operations. The successful execution of this methodology heralds a promising avenue for marine engineering practices, advocating for the optimization of large-scale offshore module installation.