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Dynamic Analysis of an Integrated Train-Bridge-Foundation-Soil System by the substructure method

INTERNATIONAL JOURNAL OF STRUCTURAL STABILITY AND DYNAMICS 2018年第5期18卷

作者： Qiao, Hong Xia, He Du, Xianting Beijing Jiaotong Univ Sch Civil Engn Beijing 100044 Peoples R China

The substructure method is applied to the dynamic analysis of a train-bridge system considering the soil-structure interaction. With this method, the integrated train-bridge-foundation-soil system is divided into the train-bridge subsystem and the soil-foundation subsystem. Further, the train-bridge subsystem is divided into the train and bridge components. The frequency-dependent impedance function of the soil-foundation subsystem is transformed into time domain by rational approximation and simulated by a high-order lumped-parameter model with masses. The equations of motion of the train and bridge components are established by the rigid-body dynamics method and the modal superposition method, respectively. Finally, the dynamic responses of the two subsystems are obtained by iterative procedures, with the influence of the soil shear velocity studied. The case study reveals that it is important to consider the effect of soil-foundation interaction in the dynamic analysis of train-bridge systems, but with the increase of the shear velocity of the soil, such influence becomes weaker.

关键词： Bridge train-bridge system soil-foundation system substructure method train

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A substructure method for the transient response of vertical cylinders subjected to shock wave of underwater explosiony

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OCEAN ENGINEERING 2020年 218卷 108128-108128页

作者： Wang, Piguang Zhang, Zhijie Yan, Qiushi Zhang, Chao Beijing Univ Technol Beijing 100124 Peoples R China Minist Educ Key Lab Urban Secur & Disaster Engn Beijing 100124 Peoples R China

Vertical cylinders are widely used as supporting structures in ocean engineering applications. Shock waves due to underwater explosives (UNDEX) can cause serious damage to offshore structures, which has attracted the interest of many researchers. The propagation characteristics of shock waves produced by UNDEX across a cylinder are a complex physical phenomenon that involves fluid-structure dynamic interactions. For the shock wave produced by UNDEX, the total pressure on a cylinder consists of three parts, including the incident shock wave pressure, scattered wave pressure and radiation pressure due to the motion of the cylinder. This paper develops an improved method for obtaining the transient response of a vertical circular cylinder subjected to UNDEX. First, an empirical formula of the shock wave pressure for far-field UNDEX is adopted as the incident shock wave. Based on the continued fraction (CF) expansion of the frequency-domain dynamic stiffness coefficient, an accurate model in the time domain for solving the scattered wave pressures on a cylinder is further developed. Then, the added mass model is used to replace the fluid-structure interaction caused by radiation wave. Finally, the vibration equation of a Euler-Bernoulli beam is utilized to evaluate the transient response of the cylinder subjected to UNDEX.

关键词： Continued fraction Scattered wave substructure method Vertical cylinder Underwater explosive

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Analysis of geometric dispersion effect of impact-induced transient waves in composite rod using dynamic substructure method

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APPLIED MATHEMATICAL MODELLING 2016年第3期40卷 1972-1988页

作者： Shen, Yunian Yin, Xiaochun Nanjing Univ Sci & Technol Dept Mech & Engn Sci Nanjing 210094 Jiangsu Peoples R China

Wave propagation in a composite rod is encountered in many contact-impact events. During the travelling of the impact-induced waves along the rod, geometric dispersion is possible when the diameter of the rod is of the same order as the wavelength. The aim of this paper is to develop an efficient method, namely dynamic substructure method to analyze the geometric dispersion of the waves in the problem of the finite-length composite rod coaxially struck by a moving rigid mass. For analyzing the geometric dispersion, a new rod element is presented through taking the lateral kinetic energy of the rod into account. The transient dynamic equation expressed by the reduced modal coordinates is derived by the Lagrange equation and the fixed-interface mode synthesis method. An adhesive contact model is used to account for contact constraint. The applications of the proposed method are demonstrated using 1) compress trapezoidal impulse and 2) impact-induced waves propagate in the large diameter rod. In order to validate the feasibility of the proposed method, the comparison is also presented "between the LS-DYNA3D solutions and the substructure solutions. It indicates that the proposed method is sufficiently accurate to compute the time history of contact force and to describe the geometric dispersion characteristics such as the attenuation of the amplitude of wavefront and the increasing of rise time. The error of the 2nd peak value of the contact force F-c2 is less than 5.0%, while the time cost of the proposed method are only 1.8% of those of the LS-DYNA3D program. Furthermore, numerical results show that the geometric dispersion results in "succession collisions" phenomenon become more complicated, and it experiences three times of the transitions from contact to separation. (C) 2015 Elsevier Inc. All rights reserved.

关键词： Wave propagation Contact-impact Dispersion effect substructure method Lateral inertia

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Experimental updating of a segmented wind turbine blade numerical model using the substructure method

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JOURNAL OF STRAIN ANALYSIS FOR ENGINEERING DESIGN 2021年第2期56卷 67-75页

作者： Yangui, Majdi Bouaziz, Slim Taktak, Mohamed Haddar, Mohamed Univ Sfax Natl Sch Engn Sfax Lab Mech Modelling & Prod LA2MP BP 1173-3038 Sfax Tunisia

During the development of the wind turbine system, blades are considered as the most critical components. The blades' dynamic characteristics must be investigated during the design process to improve their mechanical performance. This work presents an experimental updating of a segmented wind turbine blade numerical model. For this purpose, the blade segments were manufactured using the fused deposition 3D printing technology and assembled using a threaded spar and nut. For different values of the segments assembly load, the natural frequencies and damping ratios were identified using the eigensystem realization algorithm method. The dynamic behavior of the segmented blade was examined numerically using the three-node shell element, taking into consideration the additional stiffness generated by the applied assembly load. In this study, numerical and experimental modal analysis were used to identify the first five eigenfrequencies of the blade. To update the numerical model parameters, through the identified experimental results, an iterative method was developed based on the Craig-Bampton substructure approach. Results show that the blade natural frequencies are proportional to the segments assembly load. The application of the proposed method on the segmented blade numerical model updating shows that the present method is computationally efficient.

关键词： Segmented wind turbine blade finite element modeling experimental modal analysis eigensystem realization algorithm substructure method

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Prediction and mitigation analyses of ground vibrations induced by high speed train with 3-dimensional finite element method and substructure method

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JOURNAL OF VIBRATION AND CONTROL 2011年第11期17卷 1703-1720页

作者： Chen, Feng Takemiya, Hirokazu Huang, Maosong Tongji Univ Dept Geotech Engn Shanghai 200092 Peoples R China Okayama Univ Dept Environm & Civil Engn Okayama 7008530 Japan Toko Engn Consultants Ltd Tokyo Japan

This paper focuses on the dynamic interactions between a Shinkansen viaduct and the nearby ground when a high speed train is running along the viaduct. Due to the characteristics of the structure-foundation-soil system, a substructure method is employed to divide the global system into two substructures: one consists of the superstructure of track girder and supporting piers, the other consists of the foundation and near ground. Both substructures have continuity conditions at the interfaces, i.e. deformation continuity and force continuity. The superstructures are modeled by 3-dimensional (3-D) beam elements with a structural procedure, while the substructure is analyzed through a pseudo 3-D axisymmetric finite element method. A field test was conducted in the near field of the Shinkansen viaduct to examine the vibration level. The measurement data also help us to understand the wave motion influenced by the geometric properties of the structures and the moving train. Based on the field test results, a thorough interpretation is provided by analyzing both the structures and the soil. Further, computation simulation is conducted to investigate the vibrations in the ground to a wider extent. According to the nature of vibration, a combined countermeasure is proposed which involves the source motion control and the wave propagation obstruction. Satisfactory mitigation is achieved by the combined measure.

关键词： Finite element method ground vibrations soil-structure interaction substructure method vibration mitigation wave impeding barrier

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New strategy of substructure method to model long-span hybrid cable-stayed bridges under vehicle-induced vibration

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ENGINEERING STRUCTURES 2012年 34卷 421-435页

作者： Kong, X. Wu, D. J. Cai, C. S. Liu, Y. Q. Louisiana State Univ Dept Civil & Environm Engn Baton Rouge LA 70803 USA Tongji Univ Dept Bridge Engn Shanghai 200092 Peoples R China

Hybrid cable-stayed bridges consist of steel and concrete bridge segments, of which steel-concrete joints are of great importance and raise strong research interest. Due to the limitation of the traditional methods, i.e., the member finite element (FE) method and Mixed Dimensional Coupling (MDC) method, the present study proposes a substructure method to model long span bridges. The current application of the substructure method is to extract some specific parts of the whole structure to refine and analyze them. Different from the routine substructure approach, here the entire structure is modeled in detail and divided into many substructures. All the substructures are then condensed into super-elements except the concerned part. The application of the method is then illustrated through numerical studies of the vehicle-bridge coupling vibration of the Jingyue Yangtze River Bridge with a main span of 816 m. The entire bridge is first divided into many substructures with a reasonable length. Among them, the concerned substructure with 23.8 m in length including the steel-concrete joint is modeled in detail but not formed into super-element, while all the other components are modeled in detail and formed into super-elements using the component mode synthesis (CMS) method. All the components including both the super-elements and non-super-elements are then assembled into a complete and fine full bridge model. Finally, the model is used for the vehicle-induced dynamic analysis under deterministic traffic flows. The results show that the joint works well, and the transition between the steel girders and concrete beams is very smooth. (C) 2011 Elsevier Ltd. All rights reserved.

关键词： substructure method Super-element Mixed Dimensional Coupling (MDC) method Component mode synthesis (CMS) method Long-span hybrid cable-stayed bridge Steel-concrete joint Vehicle-bridge coupling analysis

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Structural damage identification based on substructure method and improved whale optimization algorithm

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JOURNAL OF CIVIL STRUCTURAL HEALTH MONITORING 2021年第2期11卷 351-380页

作者： Huang, MinShui Cheng, Xihao Lei, YongZhi Wuhan Inst Technol Sch Civil Engn & Architecture Wuhan 430073 Peoples R China

In this study, a method based on the substructure method, element relative modal strain energy, and improved whale optimization algorithm (LWOA) is implemented to identify structural damage. In this method, firstly, the global structure is decomposed into several substructures based on the substructure method, which greatly reduces the size of the model to be analyzed and improves the efficiency of analysis. Secondly, LWOA algorithm is used to calculate the severity of structural damage, Levy-flight is introduced to improve the performance of the whale optimization algorithm and solve the convergence problem of the optimization algorithm. The performance of the improved WOA algorithm is verified by four benchmarks. Then, the objective function is constructed by using the element relative mode strain energy index, which is mainly based on the change of the ratio of the element modal strain energy before and after structural damage to the modal strain energy of the global structure as the damage index. Finally, three examples, a numerical plane frame, an experimental simply supported beam, and an ASCE Benchmark frame, are used to identify the assumed damage under different conditions using the proposed method. It is found that the element relative modal strain energy near the damage location changes greatly after structural damage occurs, while that of the element relatively far away from the damaged element area is less affected. The results show that the method can accurately identify the exact location and severity of damage in different structures, which can effectively improve the efficiency of damage identification.

关键词： Damage identification substructure method Improved whale optimization algorithm Element relative modal strain energy ASCE benchmark

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Three dimensional fretting wear analysis by finite element substructure method

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INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING 2009年第4期10卷 63-69页

作者： Bae, Joon Woo Lee, Choon Yeol Chai, Young Suck Youngnam Univ Sch Mech Engn Gyongsan 712749 Kyungbuk South Korea

In steam generator of nuclear power plant, flow induced vibration in a U-tube bundle could cause wear and fatigue failure. This vibration causes fretting-wear between the supporting plates and tubes by generating infinitesimal friction. In this study, a substructure method is developed for three dimensional finite element models of fretting wear problems and its feasibility is also verified. The substructure method can reduce large amount of computation time required by conventional finite element analysis.

关键词： Fretting Wear Finite Element method substructure method Steam Generator U-tube

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An application of substructure method

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UPB Scientific Bulletin, Series A: Applied Mathematics and Physics 2006年第1期68卷 37-48页

作者： Dobre, Daniela National Institute for Building Research-INCERC Bucharest Romania

The paper deals with the mathematical description of the substructure method applied to an elastic lumped mass system subjected to an harmonic motion, in time and frequency domain. By introducing the substructure method, it becomes possible to study a system separately in two subsystems (substructures), with an interface between them, and for which the dynamic equilibrium equations are written. The system of equations is solved using explicit Newmark time integration scheme, distinguishing between the quantities coming from the substructure 1 and substructure 2.

关键词： substructure method equilibrium equations numerical integration Fourier transform impedances functions

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substructure method Revisited for Analyzing the Dynamic Interaction of Structures with Embedded Massive Foundations

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JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING 2022年第6期148卷 04022029-04022029页

作者： Conti, Riccardo Di Laora, Raffaele Niccolo Cusano Univ Dept Engn I-00166 Rome Italy Univ Campania Luigi Vanvitelli Dept Engn I-81031 Aversa CE Italy

This paper proposes a new simple approach for assessing dynamic soil-structure interaction effects on structures supported by embedded massive foundations. The classical substructure method was revisited by proposing an exact decomposition approach which allows performing the inertial interaction analysis of the superstructure without modeling foundation and soil, which are replaced by properly defined impedances. The proposed approach requires redefinition of simplified formulas for both the dynamic stiffnesses and the kinematic interaction factors, which are referred to the top of the massive foundation. Accurate expressions for the complex impedances were derived based on rigorous finite-element results. The same formulas were used to calibrate a four-spring model for the analysis of the kinematic interaction problem, resulting in different expressions for the kinematic interaction factors depending on the adopted assumptions. The proposed approach, in conjunction with the novel formulas for impedances and kinematic factors, was applied to the case of bridge piers on caisson foundations, and the results were more accurate than those of the existing simplified procedures.

关键词： substructure method Foundation impedances Kinematic interaction Embedded massive foundations Dynamic analysis

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