Home       About Journal       Editorial Board       Instruction       Subscribe       Advertisement       Contact Us       中文

Office Online     Journal Online   Current Issue Accepted Archive Advanced Search Download Articles Read Articles Email Alert   Links

2024 Vol. 43, No. 6 Published: 2024-03-28 1 Seismic performance of an earthquake resilient strongback-frame structure HUANG Qunxian1,2，LIN Congying1,2，LIU Yang1,2，HUANG Jun3 Based on the strongback mechanism, damage control, and replaceable concept, an innovative earthquake resilient strongback-frame structure is proposed to minimize earthquake-induced damage and facilitate quick and economical post-earthquake repairs. To investigate the seismic performance and resilience of the strongback-frame structure, pushover analysis on five structural models was conducted with Sap2000 software. Particular emphasis was taken on the damage mechanism, damage evolution, deformation characteristics, seismic performance, and seismic resilience of the strongback-frame structure. A two-stage calculation method for the residual deformation is proposed to evaluate the seismic resilience of structures subjected to different magnitude earthquakes. The results show that the strongback system can effectively control the lateral deformation pattern of the structure, and the story drift ratio and damage distribute uniformly, which can avoid the formation of the weak-story failure mechanism and improve the seismic performance and collapse resistance of the structure. The strongback system can also effectively mobilize the reserve capacity of the overall structural components, which enhances the overall performance. The stiffness, strength, and energy consumption capacity of the strongback frame are significantly improved, and the pushover curves do not appear the strength softening behavior. After reasonably graded damage design, the replaceable energy dissipation components set in the strongback frame play the first line of defense role to reduce the structural damage and residual deformation, effectively improving the structure's seismic resilience. 2024 Vol. 43 (6): 1-10 [Abstract] ( 235 ) HTML (1 KB)  PDF (2336 KB)  ( 204 ) 11 Reliability-based topology optimization of continuum structures under uncertain harmonic excitations WANG Xuan1,2，SHI Yuankun1，CHEN Xiang1，LONG Kai2 An effective reliability-based topology optimization method is proposed for the design problem of continuum structure considering the uncertainty of load amplitude and frequency of harmonic excitation. A reliability design optimization model of minimizing structural volume ratio under probabilistic reliability constraint is established, in which the limit state function is the sum of the amplitude squares of the degrees of freedom concerned. The analytic sensitivity formulations of limit state function with respect to design variables and random variables are derived using adjoint variable method. The Performance Measure Approach (PMA) is used to achieve reliability analysis, and the method of moving asymptotes (MMA) is used to update design variables. Finally, three numerical examples and Monte Carlo simulation are tested to verify the effectiveness and stability of the proposed method for the design problem of continuum structure under uncertain harmonic excitation. The influences of the uncertainty of amplitude and frequency of harmonic excitation, reliability index, and coefficient of variations on the optimization results are also discussed. 2024 Vol. 43 (6): 11-18 [Abstract] ( 185 ) HTML (1 KB)  PDF (1165 KB)  ( 91 ) 19 Equivalent mechanical model and vibration reduction performance analysis of a non-packed particle damper LI Xiaojun1，TIAN Chaojie1，HUANG Xuhong2 To consider the impact of time effects during collision on the vibration reduction performance and mechanism of non-packed particle damper (NPPD), an equivalent single particle mechanical model based on contact element method (EISM-CE) is proposed on the basis of existing mechanical model (EISM), and a corresponding solving algorithm of motion state of NPPD-single degree of freedom structure is suggested based on the Runge Kutta algorithm. The shaking table test of a single-layer steel frame structure with additional NPPD was also designed and conducted. The influence of filling ratio on the frequency response curve of structural displacement was explored. Further validation and comparative analysis of the EISM-CE model was conducted based on the proposed model parameter determination principle. On the basis of verifying the rationality of the equivalent model, the numerical analysis on the vibration reduction effect and energy change law under free vibration, harmonic excitation, and recorded strong ground motion was carried out subsequently. The results show that the EISM-CE model and the corresponding determination principle of model parameters are more reasonable and effective than the existing EISM. The results of the numerical analysis show that NPPD has good damping performance under different excitations. The damping performance and mechanism of EISM-CE are somewhat different from EISM after considering the collision time effect. 2024 Vol. 43 (6): 19-28 [Abstract] ( 126 ) HTML (1 KB)  PDF (2645 KB)  ( 109 ) 29 Natural vibration characteristics of an open plate based on the Gaussian wavelet function and linear expression GUO Wenjie，CHAI Tianjian，YAN Jianwei，HONG Xian Research the solution method for the natural vibration characteristics of open plates, treating the open area as a plate with zero thickness, and introducing localized Gaussian wavelet functions as displacement shape functions to capture sudden changes in thickness, thereby improving the accuracy of the solution. In this paper, a linear expression method is proposed to decouple the displacement shape function and boundary conditions. The basic idea is to find the Linear independence column vector in the constraint matrix through the Gauss elimination method, and transform the unknown coefficient in the displacement shape function into the linear expression of the linearly independent sequence vector, thus transforming the constrained problem into the unconstrained problem. Analyze the simply supported and fixed open plates on four sides, and discuss the convergence and accuracy of the solution based on the finite element method calculation results. We have studied the influence of different opening sizes and shapes on natural frequency, obtained the relationship curve between opening size and shape and natural frequency, and explained the reasons for the influence. Finally, the natural frequencies of multi opening plates under different boundary constraints are calculated. 2024 Vol. 43 (6): 29-37 [Abstract] ( 79 ) HTML (1 KB)  PDF (1669 KB)  ( 139 ) 38 Shockwave signal reconstruction method based on a serial-parallel double branch network SUN Chuanmeng1,2，CHEN Jiaxin1,2，YUAN Yue1,2，PEI Dongxing1,2，MA Tiehua1,2 Reconstructing the pressure distribution in the shock wave field by limited measurement point data and the complete shock wave pressure curve by missing data are of great value for weapon power and target damage assessment. To address the problem of reconstruction of the shockwave signal, it is proposed to establish the Res-GRU branch to capture the local timing dependence of the shockwave overpressure signal in a serial manner; to establish the Transformer branch to analyze the global potential features of the signal in a parallel manner; to establish the feature merging unit for higher-order feature integration to realize the complementary information of different stages layer by layer. Then, it is constructed a serial-parallel double branch network (denoted as G-TNet) based on GRU and Transformer model. The experimental study shows that G-TNet integrates the signal timing relationship, data variation pattern and other characteristic information; in the reconstruction experiment of pressure distribution of shockwave field based on limited measurement point data, the MSE between the reconstructed simulated and measured overpressure data and the original value were 5.0×10-6 and 1.2×10-3, the average peak error were 0.49% and 27.01%, and the average positive pressure time errors were 15.62% and 15.91%, and the average specific impulse errors were 17.66% and 19.33%, respectively; in the reconstruction experiments of the shockwave pressure curve based on the missing data, the MSE between the reconstructed simulated and measured signals and the original values were 5.0×10-6 and 5.0×10-4, and the MAE were 0.0010 and 0.0171, respectively; The G-TNet reconstruction results are better than the mainstream methods and fulfill the requirements of explosion shockwave pressure reconstruction index. 2024 Vol. 43 (6): 38-49 [Abstract] ( 76 ) HTML (1 KB)  PDF (3700 KB)  ( 66 ) 50 Experimental study on the mechanical mechanism and vibration reduction performance of suspended multi-mass pendulums SUN Haoding，HE Haoxiang，CHENG Yang，ZHANG Yaoyuan，CAO Qing Traditional suspension mass pendulums include suspension single pendulums, series suspension multiple pendulums and parallel suspension multiple pendulums. These types of pendulums are simple in structure and clear in mechanism, but narrow in tuning frequency band, excessively long hem of low-frequency super high-rise structure and excessively short hem of high-frequency high-rise structure limit their application in practical engineering. In order to solve this problem, the dynamic equation of the multi-pendulum structure with string and parallel suspension is established. In order to study the damping performance of these two types of suspension pendulum, the damping effect of the traditional suspension mass pendulum and the string and parallel suspension pendulum with spring on the controlled structure was compared and analyzed by numerical simulation, and a series of shaking table tests were carried out on five types of controlled and uncontrolled structures. The effectiveness of suspension simple pendulum, suspension string, parallel spring-free double pendulum, suspension string, parallel spring double position under traditional ground motion and four kinds of ground motion is verified. The results of numerical simulation and shaking table test show that the series suspension multi-pendulums with spring has the best damping effect, and it has the advantages of increasing the tuning frequency band, realizing the multi-order mode control and adjusting the pendulum length flexibly, which is suitable for engineering practice. 2024 Vol. 43 (6): 50-63 [Abstract] ( 96 ) HTML (1 KB)  PDF (4951 KB)  ( 103 ) 64 Fault diagnosis of rolling bearings based on mixed-cutout imbalance data augmentation and the SwinNet network HUO Jiuyuan1,2，LI Yufeng1，CHANG Chen1，LI Chaojie1，XU Jihao1 In the field of fault diagnosis for rolling bearings, this study addresses the challenges of limited fault samples and imbalanced fault categories caused by an abundance of healthy samples. Furthermore, it tackles the issues of noise and artificial label interference present in the environment. To overcome these challenges, a fault diagnosis model named SwinNet-MCIDA, combining hybrid imbalance data augmentation and the SwinNet network, is proposed.Firstly, drawing inspiration from image classification data augmentation techniques, the MCIDA algorithm is employed to crop and mix imbalanced data, generating new fault samples to augment the dataset. The enhanced dataset is then transformed into time-frequency images using wavelet transform. These images are fed into the SwinNet network model, which combines a convolutional neural network and a Swin Transformer encoder, for feature extraction and fault classification, enabling efficient diagnosis of rolling bearing faults. The experimental results demonstrate that the proposed SwinNet-MCIDA fault diagnosis method not only effectively addresses the issue of imbalanced fault categories in the field of rolling bearing fault diagnosis, but also effectively handles the presence of environmental noise and artificial label interference in fault data. 2024 Vol. 43 (6): 64-74 [Abstract] ( 98 ) HTML (1 KB)  PDF (3851 KB)  ( 55 ) 75 Design and impact energy absorption characteristics of concave-star three dimensional negative Poisson’s ratio structures WANG Weijing1,2，ZHANG Weiming2，GUO Mengfu3，YANG Jinshui1，MA Li2 Negative Poisson’s ratio structures have considerable application prospects in the field of energy absorption due to their abnormal deformation mechanism. This paper designs and characterizes a novel negative Poisson’s ratio structure with adjustable parameters. The static/dynamic mechanical properties and energy absorption characteristics are systematically studied using a combination of theoretical and numerical simulation research methods. The research results show that the new structure has excellent mechanical properties and adjustable parameters. Under static compression conditions, the new structure has higher stiffness and better energy absorption performance, with a specific energy absorption value 2.64 times that of the concave honeycomb structure and 3.89 times that of the star-shaped honeycomb structure. Under dynamic impact conditions, the energy absorption performance of the concave-star structure is better than that of two traditional honeycomb structures (concave and star-shaped) at low velocity, and its energy absorption advantage degrades at medium and high velocities, which is equivalent to the concave honeycomb structure but much higher than the star-shaped honeycomb structure. 2024 Vol. 43 (6): 75-83 [Abstract] ( 134 ) HTML (1 KB)  PDF (2620 KB)  ( 72 ) 84 Rolling bearing fault diagnosis method based on a multi-scale and improved gated recurrent neural network with dual attention WANG Min1,2，DENG Aidong1,2，MA Tianting1,2，ZHANG Yujian1,2，XUE Yuan1,2 Regarding the problem that the diagnosis accuracy of rolling bearing fault diagnosis model decreases under the variable working conditions and environmental noise interference, a rolling bearing fault diagnosis method (DAMSCN-BiGRU) composed of Multi-scale Convolutional Network based on Dual Attention mechanism (DAMSCN) and improved Bidirectional Gated Recurrent Unit (BiGRU) was proposed. Firstly, using multi-scale feature fusion module with different kernel sizes to obtain a variety of receptive fields and extract the multi-scale feature information of the original vibration signal of the bearing, which were fused adaptively according to their importance. And the multi-scale features were weighted and fused using a dual attention module composed of channel attention and spatial attention to weaken the redundant features in the fused features. Then, the attention layer was added and the segmented activation was used to improve BiGRU to mine the time-domain features of the signal to improve the performance of the bearing fault diagnosis. Finally, the classification of different faults was completed by Softmax layer. The experimental results show that compared with other intelligent diagnosis models, DAMSCN-BiGRU can achieve an average diagnostic accuracy of 98.2% under variable working condition and still has an accuracy of 85.3% in the strong noise background, and the effect is better than other commonly used models under different levels of noise intensity, which is beneficial to promote the research and practical application of intelligent fault diagnosis of rolling bearings. 2024 Vol. 43 (6): 84-92 [Abstract] ( 104 ) HTML (1 KB)  PDF (2335 KB)  ( 103 ) 93 Adaptability and safety of a toothed rail-bridge system with extra large slope under pier settlement CHEN Zhaowei1，ZHANG Mengqi1，WANG Lang1，LI Shihui1，YUAN Mi’ao1，CHEN Zhihui2，YANG Jizhong2 China has planned a number of rack railway lines with super-large slope bridges. With the increase of service time, the problem of pier settlement is difficult to avoid, and it is easy to cause excessive local stress in the rack structure. In serious cases, it will also lead to the fracture of connecting bolts, threatening the safety and stability of the rack system. To solve this problem, taking into account the complex factors such as the nonlinear meshing behavior of the gear-track, the nonlinear contact behavior of the wheel-rail and the settlement of the bridge pier, the coupled dynamic model of the rack-rail vehicle-rack (track) - super-large slope bridge system under the settlement of the bridge pier is established. It study the vertical/longitudinal deformation and stress of the rack caused by the settlement of the bridge pier when the train passes. Based on the influence of the stress of connecting bolts and the vertical/longitudinal vibration acceleration of the rack at the mid-span of the bridge, the safety control value of the settlement of the pier of the mountain railway with large slope rack is finally proposed. The research shows that under the combined action of multiple loads such as gear rack meshing and wheel rail action, the settlement of bridge pier is likely to cause the fracture of gear rail connecting bolts; When the settlement of the pier reaches 6.76 mm, the shear stress of the connecting bolt reaches its allowable shear strength of 235 MPa. It may cause fracture, seriously threatening the structural stability and driving safety; The structural stress of the gear rail is far less than the tensile strength of the gear rail; The maximum deformation of the rack can reach 140% of the settlement of the pier; The main frequency of gear rail vibration is 70~80Hz; The influence of pier settlement on the stress of connecting bolts and the deformation of gear rail is relatively significant, while the influence on the vibration and stress of gear rail is relatively small. 2024 Vol. 43 (6): 93-103 [Abstract] ( 65 ) HTML (1 KB)  PDF (2818 KB)  ( 128 ) 104 Structural load identification and response reconstruction based on a hybrid regularization method PENG Zhenrui，ZHOU Xuewen To identify the load and reconstruct the unknown response using the acceleration response of the finite structural measurement points, a hybrid regularization method combining the least square minimal residual algorithm and Tikhonov regularization method is proposed to solve the ill-posedness of load identification and response reconstruction of structures. Firstly, the transfer matrix of the structure is constructed based on the time-domain state-space model, and the load identification and response reconstruction equations are established. Secondly, the hybrid regularization method is used to improve the ill-posedness of the load identification, and the regular solution of the load is obtained. The displacement, velocity and acceleration responses of the structure are reconstructed by combining the transfer matrix of the response reconstruction equation. Finally, the proposed method is verified by numerical simulation and experimental analysis of simply supported beams. The results show that the proposed method can improve the ill-posedness of the reconstruction equation and effectively reconstruct the unknown load and various types of response of the structure. 2024 Vol. 43 (6): 104-112 [Abstract] ( 106 ) HTML (1 KB)  PDF (2773 KB)  ( 136 ) 113 Symplectic wave-based method for the free vibration analysis of cross-ply composite laminated circular cylindrical shells HAN Shaoyan1，LI Yuyin2，GAO Ruxin3,4 A symplectic wave-based method is proposed for the free vibration analysis of cross-ply laminated cylindrical shells with arbitrary boundary conditions. First, based on Kirchhoff-Love's shell theory, the governing equations of a cross-ply laminated cylindrical shell can be established in the symplectic duality system by selecting an appropriate state vector. Secondly, the characteristic equation for cross-ply composite laminated cylindrical shells is derived so that the symplectic eigenproblem can be formed. Finally, the symplectic eigensolution is substituted into the boundary conditions at both ends of the cylindrical shell, and the algebraic equation of the free vibration problem of the cylindrical shell is obtained and then solved to give the natural frequencies and modals of cross-ply composite laminated cylindrical shells. Numerical examples are given to shown the validity and accuracy of the present method through comparing the results obtained using the present and other methods. 2024 Vol. 43 (6): 113-120 [Abstract] ( 114 ) HTML (1 KB)  PDF (824 KB)  ( 96 ) 121 Seismic damage investigation and analysis on rural buildings in the Ms 6.8 Luding Earthquake CHEN Yun1，DONG Jinshuang1，ZHANG Fengchao2 To analyze the damage mechanism of rural buildings in the Ms 6.8 Luding earthquake, typical seismic damage characteristics of masonry-timber structure, brick-concrete structure and RC frame structures were summarized, based on the damage investigation of rural buildings in Moxi town, Detuo town, Yanzigou town. The classifications, statistics and analyses of seismic damage levels were carried out for rural buildings in the area with the intensity is assessed at Ⅸ degrees. The results from the investigation and analyses show that masonry-timber structure and brick-concrete structure were the most obvious structural forms of earthquake damage and obvious in this earthquake, the seismic damage of frame structure is light, generally, and the number of basically undamaged frame structures accounted for 72.5%. The typical seismic damages of the masonry-timber structure and brick-concrete structure appear to be uneven settlement of a foundation, wall cracking, floor (roof) damage, non-structural component damage, and overall collapse. The seismic damages of RC frame structures mainly include beam-column and joint damage, wall cracking and non-structural component damage. The masonry-timber structure and brick-concrete structure were seriously damaged and collapsed accounted for a higher proportion of the overall earthquake damage of these two types of buildings, the number of severely damaged masonry-timber and brick-concrete structure was about 6 times for the frame structure, while no collapse was observed for frame structures, and the largely unbroken frame structure is relatively high. In general, the RC frame structures possess the strongest seismic capacity among these three types of structures, while masonry-timber structure present the weakest. According to the earthquake-damage characteristics of different structural forms, the earthquake-prevention capability of repairable earthquake-damaged houses and existing farm houses should be improved through seismic reinforcement, and some measures should be done to improve the earthquake prevention ability of rural buildings, and then the earthquake casualties and losses can be reduced. 2024 Vol. 43 (6): 121-131 [Abstract] ( 102 ) HTML (1 KB)  PDF (4395 KB)  ( 54 ) 132 Comparative study on cross-resolution topology optimization methods based on generative adversarial networks ZHU Hepeng1,2,3，DING Zhe1,2,3，ZHANG Yan1,2,3，LI Xiaobai1,2,3 The iterative process of topology optimization involves a large number of finite element analyses and sensitivity update steps. As the number of mesh divisions increases, the optimization process consumes a significant amount of computational cost. By using deep learning methods and establishing a mapping relationship between low-resolution intermediate configurations and high-resolution topological structures, cross-resolution topology optimization design of structures can be achieved, thus greatly improving computational efficiency. This article constructs a topology optimization method capable of cross-resolution prediction based on two different generative adversarial networks, and extends it to the optimization prediction of three-dimensional structures. Firstly, with the minimization of compliance as the objective function, a dataset of optimized structures under different loading conditions, initial displacements, and volume fractions is generated using the Solid Isotropic Material with Penalization method. Then, the Pix2pix and Esrgan networks are used to solve their cross-resolution prediction problems, where for the Pix2pix network, residual modules are used to replace the convolution modules inside the generator to enhance the reuse of low-level information. Finally, the effectiveness of the proposed method is verified through two-dimensional and three-dimensional examples, and comparative studies are conducted with existing methods based on the CGAN network. The results show that considering both calculation accuracy and computational efficiency, the method based on the Esrgan network performs better and is most suitable for cross-resolution topology optimization design. 2024 Vol. 43 (6): 132-140 [Abstract] ( 101 ) HTML (1 KB)  PDF (2243 KB)  ( 62 ) 141 Analysis and optimization of seismic mitigation and isolation effects for long span steel box tied arch bridges in high intensity seismic regions SUN Jianpeng1,2，LI Jinbin1，XU Weichao1，WANG Yi3，YU Chao2 In order to study the seismic response and seismic isolation technology of long-span half-through steel box tied arch bridge under high-intensity earthquake, taking Xishuangbanna Liming Bridge as the engineering background, the actual ground motion records of similar sites were selected as input seismic waves, and the nonlinear time history analysis method was used to study the seismic isolation effect of bearing type and parameter change on arch bridge structure. The results show that compared with the ordinary bearing, the seismic isolation bearing can greatly reduce the internal force of the structure, but the longitudinal displacement increases, and the seismic isolation effect of the friction pendulum bearing is stronger than that of the lead rubber bearing. The combined seismic system of friction pendulum bearing and viscous damper can effectively reduce the longitudinal and transverse displacement, and further improve the seismic performance of the bridge. The parameter sensitivity analysis of the combined seismic system shows that the optimal parameter range is : the friction coefficient is 0.04, the radius of curvature is between 3200 mm and 4200 mm, the damping coefficient is 6000, and the damping index is between 0.2 and 0.4.Under the optimal seismic system, the structural displacement and internal force are significantly reduced, and the maximum seismic reduction rates are 75.3 % and 82.3 %, respectively, indicating that the system greatly enhances the ability of the arch bridge to resist dangerous earthquakes, which will undoubtedly provide a case for the seismic isolation design of similar bridges at the seismic design level. 2024 Vol. 43 (6): 141-150 [Abstract] ( 71 ) HTML (1 KB)  PDF (4122 KB)  ( 57 ) 151 Influence of site homogeneity on the seismic fragility of shallow-buried subway station underground structures JIANG Jiawei1，LI Wenbiao1，ZHAO Yazhi1，CHEN Guoxing1，DU Xiuli2 Site condition is one of the key factors affecting the seismic response of underground structure. This paper is to study the influence of site homogeneity on the seismic fragility of subway station underground structure. Taking the two-story two-span subway station as the research object, a two-dimensional finite element analysis model considering soil-structure interaction was established based on the ABAQUS/standard software platform. IDA method was conducted to calculate the seismic response of the structure which located in the layered site and the homogeneous site respectively. The inter-story drift ratio is selected as the damage measure and PGA is selected as the earthquake intensity measure for building the seismic fragility curves of subway station structure. The results shown that the mean of the structure response of the layered site is significantly higher than that of the homogeneous site, while the standard deviation of the two site is identical. Under the excitation of the ground motion record, the failure probability of the structure located in the layered site is significantly higher than that of the homogeneous site, which is mainly due to the large shear deformation of the soil adjacent to structure in the layered site. The finding can provide a scientific reference for the performance-based seismic design of underground structures. 2024 Vol. 43 (6): 151-156 [Abstract] ( 55 ) HTML (1 KB)  PDF (1761 KB)  ( 50 ) 157 Modeling of the bourrelet-barrel contact problem and its application MIAO Wei1,YIN Qiang1, QIAN Linfang1,2 It is of great significance to study the contact phenomena between bourrelet and bore for understanding the in-bore motion of projectile. Hence, a bourrelet-barrel contact model is proposed. It is assumed that the contact stress between a bourrelet and a rifling land only varies longitudinally along the rifling. The surface of a rifling land is simplified as a spatial curve. The geometry of the bore is then described as a cage consisting of rifling lands. An algorithm is proposed for detecting the contact between the bourrelet and rifling lands. The contact stress is calculated with an analytical solution to a 2-D contact problem by spreading the projectile and barrel out in a circular direction. The Chebyshev-Gauss quadrature is adopted to calculate the contact load on the bourrelet and rifling lands because of the square-root singularity of the contact stress. The fitting method and identification method of determining the model parameters are presented. Theoretical analysis suggests that the contact stiffness between the bourrelet and bore varies with in-bore travel of the projectile. The influence of variance of the projectile mass-center on bourrelet-bore contact type and formation of wearing grooves on the bourrelet is analyzed through numerical simulations. It is found the equivalent contact point on the bourrelet does not locate at the bourrelet center or on the bourrelet edges. 2024 Vol. 43 (6): 157-170 [Abstract] ( 115 ) HTML (1 KB)  PDF (4038 KB)  ( 138 ) 171 Energy-dissipation capacity of a self-centering prefabricated coupled shear wall with open-close gap dampers LU Zheng1,2,WANG Yan1,YAN Deyu1 To improve the energy consumption of self-centering prefabricated coupled shear wall, an open-close gap damper (OCGD) was proposed, which can adapt to large deformations near the joints and help the structure achieve both good self-centering and energy-dissipation ability. Static tests were used to obtain the hysteresis curve of the damper, which verified good energy dissipation abilities of the proposed damper. Through simulation by Opensees, it was found that the proposed damper greatly improved the energy consumption of the structure without reducing its original self-centering ability. In addition, the energy was mainly dissipated by the open-close gap dampers. The energy consumption and damage of the structure itself were small, which creates the possibility for quick repair after the earthquake. 2024 Vol. 43 (6): 171-178 [Abstract] ( 74 ) HTML (1 KB)  PDF (2257 KB)  ( 53 ) 179 Longitudinal vibration characteristics of a tapered pipe pile considering the transverse inertia effect and the vertical supporting of the surrounding soil LI Zhenya1,2,PAN Yunchao1,2,ZHANG Cun3,4,HE Xianbin1,2,LChong1,2 The longitudinal vibration characteristics of the tapered pipe pile is investigated in this paper considering the transverse inertia effect of the pile and the vertical supporting of the surrounding soil. First, the pile-soil system is partitioned into finite segments in the vertical direction to consider the special structure of the tapered pipe pile and the stratification of the surrounding soil. The Voigt model is employed to simulate the vertical supporting of the surrounding soil on the pile shaft. The dynamic governing equation for the surrounding soil is built based on the three-dimensional axisymmetric model that only considers the vertical wave effect of the soil and is solved to derive the frictional force at the piles-soil interface. Then, the dynamic governing equation for the pile is established based on the Rayleigh-Love rod model to consider the transverse inertia effect of the pile. By solving the dynamic governing equation for the pile and together with the Laplace transform and impedance function transfer method, the analytical solutions for the complex impedance and the velocity admittance considering the vertical supporting of the surrounding soil are derived. Further, the semi-analytical solution in the time domain is derived by convolution theorem and inverse Fourier transform. Finally, the reliability of the present solution is verified by comparing with the published solution. Based on the present solution, a parametric analysis is conducted to research the influence of the pile transverse inertia effect, the vertical supporting of the surrounding soil and the pile parameters on the dynamic characteristics at the pile head. 2024 Vol. 43 (6): 179-188 [Abstract] ( 56 ) HTML (1 KB)  PDF (2295 KB)  ( 47 ) 189 Mechanism of the vortex-induced vibration control for twin-box girders with central baffle plates TAN Zhongxu1,2,GUO Guohe3,4,ZHU Ledong1,2,ZHU Qing1,2,QUAN Honglie5 This study investigates the vortex-induced vibration (VIV) performance of twin-box girders and the mechanism of vortex-induced vibration control by central baffle plates through wind tunnel tests and computational fluid dynamics (CFD). The effectiveness of different types (horizontal, one vertical, and two vertical plates) and sizes of central baffle plates is compared, and the corresponding VIV control mechanisms are discussed based on the streamlines and vorticity magnitude contours. The results demonstrate that horizontal plates impede airflow, reduce wind velocity near the section, increase vortex shedding difficulty, and thus control VIV. Control effectiveness increases with plate width. Meanwhile, vertical plates stabilize vortices in small areas, prevent vortex shedding, and effectively control VIV. The control effect of two half-height vertical plates is superior to that of one full-height vertical plate, with optimization of the distance between the plates required. 2024 Vol. 43 (6): 189-195 [Abstract] ( 101 ) HTML (1 KB)  PDF (3227 KB)  ( 50 ) 196 Seismic performance of a new type of swaying self-resetting vertical tooth shear wall ZHU Guangzhi,LIUJianming,SUN Jiateng The bottom of the consolidated shear wall on the foundation, in the earthquake the most easy to damage the wall wall, and energy consumption is poor, it is not suitable to repair after the earthquake. In this paper, a new system of oscillating self-resetting vertical tooth shear wall (SCVT-SW) is proposed. The SCVT-SW system consists of reinforced concrete walls, disc spring resetting devices, mild steel dampers and vertical tooth swing supports, all of which are connected by high-strength bolts to facilitate construction and replacement of damaged parts after an earthquake. The working principle of SCVT-SW system is as follows: in the process of earthquake, the vertical disc spring resetting device on both sides of the wall provides the wall swaying reset bending moment, the mild steel damper consumes the seismic energy, and the vertical tooth swaying support plays a role of fixing the hinge support while providing the horizontal shear resistance and transferring the horizontal force on the wall to the wall foundation. The calculation formula of wall section bearing capacity in SCVT-SW system is given. Through nonlinear numerical simulation, the mechanical properties of the new shear wall and the ordinary shear wall were compared, and 9 groups of different working conditions were designed. The results show that, compared with ordinary shear walls, the skeleton curve of SCVT-SW has no obvious descending section and the residual deformation is smaller. The bearing capacity of SCVT-SW system increases with the increase of the prepressure of the disc spring device on both sides of the corner, and the maximum increase is 27.8%. The residual deformation decreases with the increase of the stiffness of the disc spring device, and the reduction of 19.4% in working condition 7 compared with working condition 5 and 46.9% in working condition 8 compared with working condition 5. Therefore, the residual deformation of SCVT-SW can be reduced by increasing the prepressure and stiffness of the disc spring device, and the effect of improving the reset ability is significant. 2024 Vol. 43 (6): 196-205 [Abstract] ( 61 ) HTML (1 KB)  PDF (2476 KB)  ( 50 ) 206 Assessment of the vibration and noise reduction performances of a channel rail dynamic vibration absorber utilizing acoustic black hole technology SHI Duojia1,ZHAO Caiyou1,YI Qiang2,ZHANG Mingkai1,GAO Xin1,WANG Ping1 The environmental vibration noise problem caused by rail transportation continues to increase, and even though there are a variety of vibration and noise reduction measures with good control effects, further enhancements are still expected to be made. In this study, a new type of channel rail dynamic vibration absorber is proposed, which combines acoustic black hole technology with the principle of dynamic vibration absorber. The objective of this absorber design is to ensure the strength and stiffness of the main structure while using additional acoustic black hole damping oscillators as energy absorbing units to transfer, absorb and dissipate the vibration energy of the main structure. In order to study the effect of acoustic black hole dynamic vibration absorber on the vibration characteristics and acoustic radiation characteristics of the channel rail, the displacement conductance and vibration attenuation rate of the channel rail under different types of dynamic vibration absorbers were evaluated using simulation analysis; the noise reduction effect of the acoustic black hole dynamic vibration absorber was calculated and analyzed using a rolling noise prediction model and the influence law of its parameters on the vibration noise of the wheel track was investigated. The results show that: the first-order pinned-pinned in the 800-1000Hz frequency range of the channel rail has a significant vibration response without measures, and the vibration attenuation rate is only 0.68dB/m. After the installation of the acoustic black hole dynamic vibration absorber, the vibration attenuation rate of the rail structure rises to 1.80dB/m, and the improvement rate can reach 265%. 2024 Vol. 43 (6): 206-215 [Abstract] ( 72 ) HTML (1 KB)  PDF (2899 KB)  ( 68 ) 216 Numerical study on the aerodynamic forces and flow around a circular cylinder under streamwise sinusoidal inflow condition YU Chunfang1,JING Hongmiao1,2,3,WANG Yangxue1,ZHANG Jitao1,SHAO Linyuan1,LIU Qingkuan1,2, 3 To further understanding of the influence of streamwise gust inflow on the aerodynamic forces and flow around a circular cylinder, a 3D large eddy simulation (LES) of flow over a circular cylinder with Reynolds number (Re) of 1000 was carried out to investigate the influence of streamwise sinusoidal inflow with different frequencies on the aerodynamic forces and flow field. The lift and drag coefficients, Strouhal number (St), recirculation length, separation angle and wake structure were analyzed in detail. The velocity of streamwise sinusoidal inflow was set as , where the frequency of the inflow ranged from 0 to 0.3Hz，U0 the mean velocity，A the amplitude of the inflow, A = 0.15 U0. The results indicated that dominant frequency of the drag coefficient was substantially consistent with the frequency of the inflow. There were three obvious peak values of the frequency of the lift coefficient, which were the value of vortex shedding frequency minus inflow frequency, vortex shedding frequency, and the value of vortex shedding frequency add inflow frequency, respectively. The St is reduced first and then increased, with increase of the sinusoidal inflow frequency, and the minimum value can be obtained when f = 0.25Hz, while the recirculation length is increased first and then decreased, and the maximum value can be obtained when f = 0.15Hz. The separation angle was unchanged when f <= St, and the minimum streamwise velocity gradually increased; nevertheless, the separation angle gradually increased when f > St, and the minimum streamwise velocity gradually decreased. 2024 Vol. 43 (6): 216-224 [Abstract] ( 84 ) HTML (1 KB)  PDF (2889 KB)  ( 144 ) 225 Dynamic response analysis of GFRP-concrete compined beams under cumulative impact loading YANG Lihui1,ZHOU Wenbo1,WANG Yan2,ZHANG Haotian3,GONG Xunxun1 To investigate the dynamic response of glass fiber composite (GFRP)-concrete combination beams under multiple rockfall impact loads, one pure GFRP beam and four GFRP-concrete combination beams were subjected to cumulative impact tests using a rocking arm drop hammer testing machine, and the displacement, impact force, strain time course curves and crack development states of the test beams under different working conditions were obtained, and the damage evolution process of the beams was discussed in stages. The test results show that the pure GFRP beams have excellent impact resistance, but the deformation under the impact load is too large; the damage of the combined beams are all characterized by the concrete main crack penetration and the peeling of the GFRP-concrete interface, and good interfacial adhesion performance is the key to ensure the improvement of the impact resistance of the combined GFRP-concrete beams; under the vertical impact load, the increase of the concrete thickness can obviously reduce the damage of the same Under the vertical impact load, the increase of concrete thickness can significantly reduce the deformation response in the span of the beam at the same impact height; the ability of the test beam to resist the lateral impact is better than its ability to resist the vertical impact. The cumulative impact model of GFRP-concrete composite beam was established by using the display dynamic analysis software LS-DYNA, and the influence law of parameters such as impact hammer mass, impact velocity and section height ratio on the dynamic response of GFRP-concrete composite beam was analyzed based on this model. 2024 Vol. 43 (6): 225-237 [Abstract] ( 57 ) HTML (1 KB)  PDF (4832 KB)  ( 79 ) 238 Seismic behavior of steel tubed reinforced concrete column joints with lead viscoelastic dampers WANG Qiuwei1,2,JING Xuanguang1,SHI Qingxuan1,2,LI Xuemei1 In view of the weak seismic behavior of steel tubed reinforced concrete (STRC) column joints, an improved lead viscoelastic damper is proposed for strengthening. Based on the ABAQUS working platform, a finite element model was established for the lead viscoelastic damper specimen. The hysteresis and skeleton curves, energy dissipation, and fatigue behavior obtained from numerical calculations were compared with the experimental results, and the two were in good agreement. On this basis, the effects of lead core diameter, lead core arrangement, and composite viscoelastic thickness ratio on the mechanical properties of lead viscoelastic dampers were explored. The results show that compared to the fan-shaped lead viscoelastic damper, the improved quadrilateral lead viscoelastic damper exhibits better mechanical performance; As the diameter of the lead core increases, the energy dissipation capacity indicators of the damper are significantly improved; It is recommended to take 2 lead cores, with a ratio of 6% to 8% between the lead core area and the composite viscoelastic layer area, and a thickness ratio of approximately 0.67 for the composite viscoelastic body. Establish specimen models of lead viscoelastic dampers reinforced STRC column joints with different arrangement schemes, compare and analyze their failure modes, hysteresis characteristics, and stirrup stress, and provide reasonable arrangement schemes for practical engineering reference. 2024 Vol. 43 (6): 238-247 [Abstract] ( 55 ) HTML (1 KB)  PDF (4315 KB)  ( 56 ) 248 Wheel profile optimization design of a small wheel diameter uniform load combination style of freight bogie CAO Yufeng1,2,ZHANG Weihua1,QI Yayun1,3,CHI Maoru1,WANG Hongkun2 Small-diameter wheel bogie technology is a key technology for humpback transport vehicles. The wheel wear problem of small wheel diameter low floor backpack freight car is serious and has a serious impact on its dynamic performance. In order to further improve its operation performance, the wheel profile optimized design of small wheel diameter low floor backpack freight car is carried out. Firstly, a small wheel diameter low floor backpack freight car vehicle dynamic model is established, then the wheel profile is optimized by using the wheel diameter difference inverse design method, and finally the vehicle dynamics model is used to verify the vehicle dynamics performance and wear characteristics of the optimized profile. The results show that the optimized profile further reduces the equivalent wheel conicity and reduces the wheel-rail normal contact stress. By comparing the dynamics before and after optimization, the optimized wheel profile effectively increases the critical speed of empty and heavy vehicles by 23.3% compared to the LM profile, and the critical speed of heavy vehicles by 17.54% compared to the LM profile. Finally, the wheel wear model was used to calculate the wheel wear in the straight and curved tracks. The maximum depth of wheel wear on the outside of the curve was reduced by 54.8% and the maximum depth of wheel wear on the inside of the curve was reduced by 48.13%. The optimization of the wheel profile can effectively reduce wheel wear in the straight and curved tracks of the small wheel diameter low floor backpack freight car, which has an important role in suppressing wheel wear and improving operation performance. 2024 Vol. 43 (6): 248-254 [Abstract] ( 69 ) HTML (1 KB)  PDF (3082 KB)  ( 32 ) 255 Effects of hydrogen content on methane/air deflagration characteristics under a weak constraint condition ZHANG Beibei1, CHENG Yangfan1，2, XIA Yu2, QIAN Jiaqi2, WEI Xiao2 In the study, a self-made visual gas explosion experimental equipment was used to simulate the weak constraint space with latex balloon as a reaction vessel. The characteristic parameters of explosion flame temperature field, explosion pressure and flame propagation velocity of methane/air premixed gas with different hydrogen addition were studied. Combined with the experimental test and Chemkin software simulation results, the effects of hydrogen concentration on the explosion characteristics of methane/air were analyzed in detail. The results showed that as the hydrogen content increased, the internal field of the mixed gas combustion flame became lower, and the temperature of flame edge increased. The peak overpressure and the maximum pressure rising rate of the premixed gas increased gradually. Since the mole fractions of H, O and OH radicals increased with hydrogen addition, the flame propagation velocity was accelerated. Meanwhile, through the sensitivity analysis of the mixed-gas, it was found that the combustion of hydrogen would be inhibited by the presence of methane inhibits to a certain extent. 2024 Vol. 43 (6): 255-261 [Abstract] ( 48 ) HTML (1 KB)  PDF (2310 KB)  ( 34 ) 262 Implementation and vibration control of an array multi-tuned mass damping system for modular buildings HE Qingguang1,2,ZHANG Shiquan1， ZHU Qiankun1,2， HONG Qikai1 A modularized suspended floors system (MSFS) was proposed based on the principle of building modularity and vibration controlling by using suspended floors. A distributed array multiple tuned mass dampers (d-array-MTMDs) system was constructed using floor stabs as TMDs. Thirty-two ground motion records were entered for time-history analysis and the optimal values of the five parameters are given, including the average tuning frequency ratio η, the tuning bandwidth coefficient β, the tuning damping ratio ζT, the number of TMDs n, and the number of layers N of the main structure. The results show that the damping effect of d-array-MTMDs system is better than that of ordinary MTMDs system. ζT has little influence on the vibration control performance of the system. When η is 0.7~1.0 and β is 2.0, the system has the best vibration control effect. When n is greater than a certain threshold, the vibration control effect and stability of the system are improved significantly. The threshold is positively correlated with η and negatively correlated with ζT. With the increase of the number of a module building storey, the system can also maintain an improved vibration control effect. 2024 Vol. 43 (6): 262-272 [Abstract] ( 61 ) HTML (1 KB)  PDF (2532 KB)  ( 45 ) 273 Fatigue test of metal rubber bridge bearings ZHANG Heng1, XIA Xiushen1, QIAO Xin1, ZHU Zhijie1, DAI Shengyong2 With a highway bridge as the engineering background, two full-scale metal-rubber bridge bearing specimens were designed and fabricated, and 2 million times of vertical fatigue tests were carried out to explore the change of mechanical properties of the bearings before and after fatigue. During the fatigue test, a compression test was conducted every 200,000 cycles, and a set of vertical compression hysteresis curves of the bearings were obtained. The horizontal shear hysteresis curves were obtained from the bearing compression shear test before and after the fatigue test. The fatigue damage factor was introduced to quantitatively characterize the fatigue damage of the metal-rubber bridge bearings. The results showed that the fatigue damage of the metal-rubber bridge bearing was mainly manifested by the wear between the internal metal wires, local broken wires and lost wires. The fatigue damage will significantly reduce the horizontal bearing capacity, post-yield stiffness and equivalent shear stiffness of one side of the bearing, and make the horizontal shear hysteresis curve of the bearing become obviously asymmetric, but will increase the overall energy dissipation capacity of the bearing. The shear equivalent stiffness, vertical equivalent stiffness and vertical equivalent damping ratio after 2 million fatigue cycles are less than 0.3, and the bearing has good fatigue performance. 2024 Vol. 43 (6): 273-279 [Abstract] ( 76 ) HTML (1 KB)  PDF (1850 KB)  ( 78 ) 280 Experimental investigation on the flow-induced vibration of three tandem roughness cylinders in high Reynolds number flow LI Huaijun, SUN Hai Flow-induced vibration (FIV) of three roughness cylinders arranged in tandem is investigated at high Reynolds number. The influence of the spring stiffness and the spacing ratio on amplitude responses, frequency responses and frequency spectrums of displacement responses is analyzed and discussed. Meanwhile, comparison to the experimental results of two tandem roughness cylinders reveals the influence law of the number of the interference cylinder for FIV of the disturbed cylinder. The results show that in the initial branch, the shielding effect of the upstream cylinder on the downstream cylinder is vigorous, whereas in the upper branch, the phenomenon that the amplitude of the downstream cylinder is higher than that of the upstream cylinder appears. In the upper branch and the transition region, increasing the number of the downstream interference cylinder is able to decrease the oscillation frequency of the upstream cylinder. In the vortex-induced vibration region, the increase in the number of downstream interference cylinder scarcely affects the amplitude of the upstream cylinder. In the galloping region, the increase in the number of upstream interference cylinder tends to reduce the amplitude of the downstream cylinder, and this effect becomes weaker with increasing stiffness. The influence of the spacing ratio on the FIV of three tandem roughness cylinders is obvious. 2024 Vol. 43 (6): 280-287 [Abstract] ( 58 ) HTML (1 KB)  PDF (1835 KB)  ( 41 ) 288 Seismic performance of an asymmetric twin-tower connected structure based on the hybrid energy dissipation technology CAI Zheng1,2， PAN Wen1,2， ZHOU Qiang1,2， GHAFAR Wahab Abdul1,2， YANG Jing1,2 An asymmetrical twin-tower connected super high-rise structure was studied here and the seismic wave matching the building's site conditions was chosen as the excitation. The non-linear dynamic time analysis of the structure was used to study the energy dissipation and damping effect of the hybrid energy dissipation and damping connected structure under the action of various intensity earthquakes. The influences of the position change of BRB and cantilever truss with viscous dampers on structural aseismic performances were discussed. Moreover, the energy dissipation and damage assessments of the entire tower were studied and discussed in detail. The results show that the structure has better damping effect when the damper is arranged in the strengthened story in the middle and upper part of the connected structure. Under different seismic levels, BRB and cantilever truss with viscous dampers dissipate energy in stages and have different energy efficiency, the hybrid energy dissipation and damping technology can integrate the advantages of different types of dampers, so that the connected structure has a more comprehensive seismic performance. In terms of deformation control, hybrid energy dissipation and damping technology can reduce the torsional effect and inter-story drift ratio of the connected structure. In terms of member energy dissipation, it reduces the degree of plasticity of the main members and lowers the stress level of the structure's main stress-bearing members. The results provided a reference for further research and application of hybrid energy dissipation and damping technology in connected super high-rise structures. 2024 Vol. 43 (6): 288-300 [Abstract] ( 52 ) HTML (1 KB)  PDF (3859 KB)  ( 53 ) 301 Minimum curve radius and transition curve length of a medium and low speed maglev LIN Yuanyang， LI Miao， MA Weihua， WANG Bo， ZHANG Min， ZUO Feifei In order to study the minimum curve radius and transition curve length of medium and low speed maglev, this paper deduces the calculation formula of curve radius and transition curve length suitable for medium and low speed maglev based on the calculation method of maglev traffic line parameters, related factors, and the characteristics of the line itself. On the basis of referring to relevant standards, a theoretical analysis is carried out on the minimum horizontal and vertical curve radius and the length of the transition curve when the medium and low speed maglev trains run at a speed of 20~160 km/h, and their recommended values are further given. The reliability of the value is verified with the dynamic simulation of the vehicle model with feedback control characteristics. The research results show that the radius of the minimum horizontal curve is controlled with the maximum lateral acceleration pointing to the outside, and the radius of the minimum vertical curve is controlled with the maximum normal acceleration on the concave curve. When the train speed is fixed, the larger the horizontal slope angle, the smaller the minimum flat curve radius value, and the longitudinal slope has almost no effect on the minimum vertical curve radius value; When the cross slope angle is 2° and the train is running under normal conditions, the length of the minimum transition curve is mainly controlled with the maximum lateral impact, when running under difficult conditions, the length of the minimum transition curve is mainly controlled with the maximum normal impact. When the cross slope angle is 4° or 6° and the train is running under normal/difficult conditions, the minimum transition curve length is mainly controlled with the maximum normal shock; Considering the maximum cross-slope angle of 6°, when the train is operating at 160 km/h under normal conditions, it is suggested that the radius of the minimum horizontal curve and the length of the transition curve should be taken as 970 m and 120 m respectively. The research results of this paper can provide theoretical basis and data reference for the route selection design of medium and low speed maglev traffic. 2024 Vol. 43 (6): 301-310 [Abstract] ( 55 ) HTML (1 KB)  PDF (2352 KB)  ( 29 ) 311 Time-domain dimension-reduction modeling of ground motion processes RUAN Xinxin1,2， LIU Zhangjun2， JIANG Yunmu2 Modeling of ground motion is the basis of stochastic seismic response and dynamic reliability analysis of engineering structures. To this end, a new time-domain dimension-reduction model of ground motion process was proposed, and the values of deterministic parameters and the probability distribution of random parameters in the model were suggested. Firstly, based on the basic theory of time-domain representation of stationary process, time-domain representation forms of stationary and non-stationary ground motion processes were derived. By introducing the idea of dimension reduction of random functions, time-domain dimension-reduction representation of ground motion processes was realized. Meanwhile, based on the measured strong motion records, the parameter identification method of the time-domain dimension-reduction model of ground motion was given, and then the deterministic values or probability distributions of the basic parameters in the model were obtained. Finally, the dimension-reduction simulation analysis of the ground motion process was carried out and compared with the response spectrum and Fourier amplitude spectrum of the measured strong motion records. The results show that the time-domain dimension-reduction model of ground motion process has good accuracy, convergence and engineering applicability, and the representative ground motion time history generated can reflect the natural variability of ground motion. 2024 Vol. 43 (6): 311-319 [Abstract] ( 53 ) HTML (1 KB)  PDF (1190 KB)  ( 86 ) 320 Lifetime prediction of bearings based on the Transformer-LSTM network ZHANG Fan1,2， YAO Dechen1,2， YAO Shengzhuo1， YANG Jianwei1,2， WANG Yanliang1,2， WEI Minghui1,2， HU Zhongshuo3 Bearing is an important component in rotating machinery. Due to the working conditions, materials, and processing methods, the lifetimes of bearing have large fluctuations. Traditional parallel or serial neural network prediction methods have seriously dependent on the data sets. Therefore, there is a need for bearings RUL prediction network that can be applied to different data lengths. To overcome this challenge, a Transformer-LSTM serial-parallel neural network prediction model is proposed, which can predict the RUL for bearings with different lifetimes. By reconfiguring the Transformer decoding layer and fusing it with the LSTM network structure, the serial-parallel prediction processing of bearing life data is achieved. The experimental results show that the Transformer-LSTM neural network can accurately predict the bearing failure time for different lifetimes, including: long, medium, and short. Moreover, the model has a stronger generalization ability which also indicates that the proposed method can improve the prediction accuracy of bearing life. 2024 Vol. 43 (6): 320-328 [Abstract] ( 100 ) HTML (1 KB)  PDF (1759 KB)  ( 84 ) 329 Torsional free vibration of circular opening I-section cellular beams HUANG Bin, ZHANG Wenfu A continuous model for the cellular beams was proposed from the perspective of the energy equivalence. The energy functional model of cellular beams was established in accordance with the Plate-Beam theory concept, where the nominal warping constant, uniform torsional rigidity, rotation moment of inertia were given out. The equilibrium differential equation was derived based on the variational operation, the trial displacement function for which was postulated to yield the frequency of the torsional free vibration mode. The prediction accuracy of the theoretical results was examined against numerical results. Subsequently, the rotation of the terminal section of the cantilever cellular specimens with circular opening subjected to concentrated torque were theoretically and numerically analyzed, which proved the positive applicability of the continuous models established with accordance to the Plate-Beam theory. The torsional free vibration analysis process and derivation steps for the cellular beams with circular opening provided a replicable reference for the other opening type ones. 2024 Vol. 43 (6): 329-335 [Abstract] ( 62 ) HTML (1 KB)  PDF (1172 KB)  ( 35 ) 336 Stochastic reliability analysis method for environmental vibration source strength prediction ZHANG Xiaokai, WEI Kai Due to the difference of engineering conditions between different lines, the prediction accuracy of environmental vibration source strength of 18 guidelines semi-empirical model is low, which wastes a lot of time and economic cost in the subsequent vibration reduction work. In order to improve the prediction accuracy, realize the precise screening of sensitive points of environmental vibration, and save the cost of vibration reduction. A vehicle-track-shield tunnel coupling vibration model was established to reflect the tunnel wall vibration. Based on MC method, a stochastic reliability analysis method was proposed for the prediction of environmental vibration source strength. Three correction items in the semi-empirical model, CW, CR and CT, were taken as examples. The main factors leading to the random discreteness of the prediction accuracy of correction items are analyzed and the corresponding standardization management suggestions are put forward. The main research conclusions are as follows: The established model has high computational efficiency and accuracy, and the calculation time of a single working condition is 90s, which can make up for the shortcoming of the time consuming MC method. The time domain amplitude error is less than 12%, and the source intensity error is less than 1dB. The difference of nonlinear carrier frequency varying stiffness between different elastic pads of the same fastener is an important reason for the random dispersion of CW accuracy, which leads to the error of -1~+3dB in the prediction of source strength; The difference of rail wear grade between different lines is an important reason for the random discretization of CR accuracy, which will lead to the error of -3~+3dB in the prediction of source strength. The large difference of elastic modulus between different medium and hard soils is an important reason for the random dispersion of CT accuracy. When soil shear wave velocity is between 250 and 375m/s, the accuracy of CT is relatively high, while when it is between 375 and 500m/s, the accuracy of CT is low, and the prediction error can reach 3dB. Considering the errors brought by multiple correction items at the same time, the error range of source strength prediction can reach -4~+9dB, and it is very possible to adopt vibration reduction measures that do not meet the actual requirements of section during design, thus wasting a lot of vibration reduction costs. Therefore, it is suggested to strictly control the randomness of related factors such as nonlinear carrier frequency variable stiffness of elastic plate of fasteners and rail wear grade. At the same time, the medium-hard soils are divided into two types by shear wave velocity of 375m/s and corresponding correction terms are given. 2024 Vol. 43 (6): 336-344 [Abstract] ( 85 ) HTML (1 KB)  PDF (1900 KB)  ( 142 )

Copyright © 2015 JOURNAL OF VIBRATION AND SHOCK TEL: +86-21-62821366　http://jvs.sjtu.edu.cn　E-mail: jvs@sjtu.edu.cn Support by Beijing Magtech support@magtech.com.cn