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A beam string structure is an efficient hybrid system comprising beams, cables, and struts. This study proposes an active beam string structure that adapts to external loading for deflection control, achieved by replacing passive struts with telescopic ones. An optimization-based model is created to minimize deflection, with the maximum deflection of beams serving as the optimization objective. A deflection control framework is constructed by using a hybrid genetic algorithm and back-propagation neural network. The former combines the strengths of the genetic and gradient descent algorithms, and the latter trains a prediction network applying mechanical responses, resulting in quick output of control schemes. To assess the control framework's performance, a scaled model is designed and fabricated, including a measuring system for deflection and stress, an actuating system with telescopic struts, and a PC-based decision-making system. Experimental and numerical studies are carried out for the model. The control schemes using the hybrid genetic algorithm and back-propagation neural network successfully reduced the deflection responses by at least 80% in simulations and experiments. The results validate the accuracy of the algorithm and reliability of the network, further demonstrating the effectiveness of the control framework. In addition, the deflection control process also optimizes the internal forces of the beam, with a maximum decline rate of stress response approaching 60%. [ABSTRACT FROM AUTHOR]

In this study, the mechanical responses of a functionally graded thick-walled tube simultaneously under magnetic, thermal and mechanical loads are studied. Based on the assumption that the volume fraction of each phase material is distributed as a power function, the Voigt method is used to obtain the stress–strain relationship of the functionally graded materials (FGMs). The influences of the relevant material parameters including volume fraction, thermal expansion coefficient, and Poisson's ratio on the magneto-thermo-elastic theoretical solution are deeply studied and discussed. Furthermore, when some of the parameters are set as special values, the research results can be degenerated to two coupled loads which are consistent with the existing researches. The results of this paper provide theoretical support for the practical design and application of the FGM tube under the combined action of magnetic, thermal and mechanical loads. [ABSTRACT FROM AUTHOR]

Long-term monitoring of spatial structures is of great importance for the full understanding of their performance and safety. The missing part of the monitoring data link will affect the data analysis and safety assessment of the structure. Based on the long-term monitoring data of the steel structure of the Hangzhou Olympic Center Stadium, the correlation between the stress change of the measuring points is studied, and an interpolation method of the missing stress data is proposed. Stress data of correlated measuring points are selected in the 3 months of the season when missing data is required for fitting correlation. Data of daytime and nighttime are fitted separately for interpolation. For a simple linear regression when single point’s correlation coefficient is 0.9 or more, the average error of interpolation is about 5%. For multiple linear regression, the interpolation accuracy is not significantly increased after the number of correlated points is more than 6. Stress baseline value of construction step should be calculated before interpolating missing data in the construction stage, and the average error is within 10%. The interpolation error of continuous missing data is slightly larger than that of the discrete missing data. The data missing rate of this method should better not exceed 30%. Finally, a measuring point’s missing monitoring data is restored to verify the validity of the method. [ABSTRACT FROM AUTHOR]

A structural analysis framework called the finite particle method (FPM) for structure failure simulation is presented in this paper. The traditional finite-element method is generated from continuum mechanics and the variational principle; vector mechanics form the basis of FPM. It discretizes the domain with finite particles whose motions are described by Newton's second law. Instead of imposing a global equilibrium of the entire continuous system, FPM enforces equilibrium on each particle. Thus, particles are free to separate from one another, which is advantageous in the simulation of structural failure. One of the features of this approach is that no iterations to follow nonlinear laws are necessary, and no global matrices are formed or solved in this method. A convected material frame is used to evaluate the structure deformation and internal force. The explicit time integration is adopted to solve the equation of motion. To simulate the truss structure failure, a failure criterion on the basis of the ideal plastic constitutive model and a failure modeling algorithm are proposed by using FPM. According to the energy conservation study of a two-dimensional (2D) truss, the energy is decomposed and balanced during the failure process. Also, a more complicated three-dimensional (3D) structure failure simulation is given. The comparison of the simulation results and the practical failure mode shows the capability of this method. [ABSTRACT FROM AUTHOR]

In this paper, a three-member tensegrity structure is used as a conceptual model for the dendritic actin network in living cells. The pre and postbuckling behavior of the tensegrity is analyzed basing on the energy method. Analytical simulations are carried out on the tensegrity by using the experimentally obtained scales and mechanic properties of actin-filaments for the structural members of the tensegrity. The model exhibits a stress stiffening regime followed by a stress softening regime in the load-stiffness relationship, which qualitatively tallies with the experimentally observed response of actin networks. Due to the simplicity of the model, there is only a single compressed member and the structure buckles abruptly, which results a softening regime much steeper than that observed in the actin network. To take the member length variety into account, we propose a conceptual large-scale tensegrity system with various member lengths, and its behavior is approximately estimated by the mean response of a large number of three-member tensegrity cells with their member length varying in the range of filament lengths. The obtained mean response exhibits a much better fitness to the response of actin networks than those exhibited by the single tensegrity model. The findings reported in this paper indicate that the dendritic actin network may work as a complex tensegrity system, when it is subjected to a stress. [ABSTRACT FROM AUTHOR]

Rubber bearings are crucial components in seismic isolation systems to mitigate the damaging effects of earthquakes on structures. Rubber bearings generally consist of alternate layers of steel and rubber bonded together. Simplified two-point spring models omit this layered construction and have limitations in adaptability and programmability, while refined multiple solid models lead to substantial computational costs. This study presents an effective and efficient approach to simulate rubber bearings by using multi-layered solid element based on the finite particle method (FPM). The traditional "Zigzag" shape function is extended into the 3D situation to reflect the serrated deformation within the layered construction. Based on the simplified assumption of stress continuity, an iterative approach is presented for the deformation gradient to achieve the force continuity between layers in dynamic nonlinear scenarios. The multi-layered solid models for both natural rubber bearings (NRBs) and lead rubber bearings (LRBs) are proposed based on this element. The errors of the hysteresis curves of rubber bearings are below 3.1 % between the numerical results obtained by using the multi-layered solid model and the experimental results. The computational speedup ratio of the proposed multi-layered solid model is verified to be 19 relative to the refined multiple solid model. The proposed method is applied to a base-isolated frame structure to demonstrate its effectiveness in structural seismic analysis. • A novel approach to model rubber bearings by using multi-layered solid element is proposed. • Zigzag shape function is adopted inside the element to keep stress continuity. • Multi-layered solid models for natural rubber bearings and lead rubber bearings are presented and validated. • The proposed method is applied to a base-isolated frame structure with lead rubber bearings. [ABSTRACT FROM AUTHOR]

This paper presents an enhanced fiber-based approach for the seismic analyses of the behavior of steel structural members. This approach is built based on the framework of the finite particle method. Specifically, a fiber-beam element is developed to model the behaviors of structural members more elaborately. A cyclic constitutive model for fiber is proposed by enhancing a uniaxial steel hysteretic constitutive relationship to consider large strain amplitude and low cyclic fatigue. In addition, a fiber-based fracture model is proposed for modeling the progressive failure process of members. The proposed enhanced approach combines the finite particle method and fiber-beam element with more elaborated constitutive and fracture models, and it has the advantages in evaluating the cross-sectional plastic development and dealing with non-linear and non-continuum problems, which is suitable for analyzing the cyclic fatigue, buckling, and fracture of steel structural members. The analyses of steel plates and steel tube member specimens are performed to verify the effectiveness of the proposed approach. The proposed method is applied to analyze the collapse of a Kiwitt-8 single-layer latticed dome subjected to different seismic loads, which shows the feasibility of the fiber-based approach for seismic collapse analysis. • Enhanced fiber-based approach for analysis of steel structural members is proposed. • An FPM fiber-beam element considering fracture is introduced and verified. • An improved uniaxial steel cyclic constitutive model is proposed and verified. • Seismic collapse behavior of a typical single-layer latticed dome is obtained. [ABSTRACT FROM AUTHOR]