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Concise semi-analytical solution for group piles impedance function and generalized group factor analysis considering SSI effect

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ENGINEERING ANALYSIS WITH BOUNDARY ELEMENTS 2025年 176卷

作者： Hou, Hongwei Li, Jianbo Li, Zhiyuan Lin, Gao Dalian Univ Technol State Key Lab Coast & Offshore Engn Dalian 116024 Peoples R China Dalian Univ Technol Inst Earthquake Engn Dalian 116024 Peoples R China China Inst Water Resources & Hydropower Res Earthquake Engn Res Ctr Beijing 100038 Peoples R China

It is foremost to investigate group piles dynamic response for large nuclear island structure considering highprecision soil structure interaction (SSI). However, the existing group piles effect obtained using static stiffness cannot reflect to the frequency dependence, and the spatial coupling characteristics of far-field artificial boundary limits the efficient and fine impedance function computation for large piles under complex foundation conditions. In present paper, a refined impedance function procedure for large-scale group piles is built on the scaled boundary finite element method (SBFEM). The far-field stiffness matrix is made to localize the spatial coupling using decoupling technique, a Runge-Kutta search strategy on frequency with zero-frequency starting is developed to obtain the complete stiffness matrix, and a generalized group factor calculation is proposed. The accuracy and effectiveness are proved with the cases of impedance function for small-scale group piles. At length, some fine large-scale nuclear island group piles model is investigated. All cases demonstrate that the pile impedance function, especially under the condition of layered ground, presents very obvious frequency correlations in the simulation of large-scale nuclear island group piles, which further confirms that the provided method has good engineering applicability.

关键词： Group factor impedance function Partitioned decoupling Nuclear island structure Modified SBFEM Parallel computation

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Study of an impedance function for Mixed Traffic Flows Considering the Travel Time-Cost Characteristics of Long-Distance Electric Vehicle Trips

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APPLIED SCIENCES-BASEL 2024年第16期14卷 7138页

作者： Wang, Ning Gu, Jian Jing, Wei Huang, Fu-An Zhu, Hang Changsha Univ Sci & Technol Sch Traff & Transportat Engn Changsha 410004 Peoples R China Changsha Univ Sci & Technol Hunan Key Lab Smart Roadway & Cooperat Vehicle Inf Changsha 410114 Peoples R China

To quantify the travel time and cost characteristics of mixed traffic involving electric vehicles (EVs) and fuel-powered vehicles on roads, in this paper, we comprehensively consider three factors affecting road impedance: queue length, waiting time, and service rate. Initially, a time characteristic function and a cost characteristic function for mixed traffic impedance are constructed. From the perspective of travel time, we consider the impact of EV penetration on the actual road capacity and introduce a capacity coefficient to modify the BPR (Bureau of Public Roads) road impedance function. Given that different types of vehicles might need to wait at charging stations, we employ queuing theory to calculate the queuing time at these stations and construct an impedance model that considers travel time. From the perspective of travel costs, we account for the energy consumption costs and road usage fees for different types of vehicles. The energy consumption cost for travel mileage is obtained by multiplying the unit mileage energy consumption cost of mixed traffic by the travel mileage. For road usage fees, we adopt the conventional method of multiplying the per-kilometer rate for each vehicle type by the travel mileage, thus constructing an impedance model that incorporates travel costs. Finally, in the numerical analysis section, based on the vehicle travel mileage, we categorize travel into short-, medium-, and long-distance trips for analysis. With the constructed mixed traffic impedance model, we conduct a detailed analysis of the travel time and cost characteristics of mixed traffic over different travel distances. We explore the specific impacts of the electric vehicle penetration rate, traffic flow volume, and travel mileage on road impedance. The results indicate that as the penetration rate of electric vehicles increases, the total energy consumption of the transportation system significantly decreases. Moreover, at high electric vehicle penetration rate

关键词： impedance function electric vehicles mixed traffic flow travel time travel cost queueing system

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Traffic Flow Assignment Model with Modified impedance function

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KSCE JOURNAL OF CIVIL ENGINEERING 2018年第10期22卷 4116-4126页

作者： Zou, Yuan-Yang Xu, Xue-Guo Hu, Yu Lin, Gui-Hua Shanghai Univ Sch Management Shanghai 200444 Peoples R China

In this paper, we study a mixed-mode traffic network, in which Battery Electric Vehicles (BEVs) and Gasoline Vehicles (GVs) can be driven freely. We propose a new piecewise impedance function and, based on this new impedance function, we present a convex but nonsmooth optimization model for the traffic network. In order to deal with the nonsmoothness, we introduce a binary variable. Furthermore, we report some numerical examples to show the efficiency of the model. %is effective and robust. In particular, our numerical results illustrate that, if the distance limit of BEVs is long enough and the unit operating cost of BEVs is lower than GVs, more travelers prefer to choosing BEVs.

关键词： impedance function BEVs GVs mixed-mode traffic network

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A mixed-mode traffic assignment model with new time-flow impedance function

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INTERNATIONAL JOURNAL OF MODERN PHYSICS B 2018年第3期32卷 1850017-1850017页

作者： Lin, Gui-Hua Hu, Yu Zou, Yuan-Yang Shanghai Univ Sch Management Shanghai 200444 Peoples R China

Recently, with the wide adoption of electric vehicles, transportation network has shown different characteristics and been further developed. In this paper, we present a new time-flow impedance function, which may be more realistic than the existing time-flow impedance functions. Based on this new impedance function, we present an optimization model for a mixed-mode traffic network in which battery electric vehicles (BEVs) and gasoline vehicles (GVs) are chosen. We suggest two approaches to handle the model: One is to use the interior point (IP) algorithm and the other is to employ the sequential quadratic programming (SQP) algorithm. Three numerical examples are presented to illustrate the efficiency of these approaches. In particular, our numerical results show that more travelers prefer to choosing BEVs when the distance limit of BEVs is long enough and the unit operating cost of GVs is higher than that of BEVs, and the SQP algorithm is faster than the IP algorithm.

关键词： impedance function BEVs GVs mixed-mode traffic network

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Bstj 48: 3. March 1969: Extension of Bode's Constant Resistance Lattice Synthesis of Transfer impedance function. (Lee, S.Y.)

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2016年

Bstj 48: 3. March 1969: Extension of Bode's Constant Resistance Lattice Synthesis of Transfer impedance function. (Lee, S.Y.) by published by

关键词： (lee, bode's constant constant resistance element values exp explicit formulas extension impedance impedance function lattice lattice synthesis poles resistance lattice second degree structures structures vii synthesis system technical transfer transfer impedance vii viii zeros

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impedance function calculation for the study of waves in locally periodic arrangements

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EUROPEAN JOURNAL OF PHYSICS 2015年第5期36卷 055034-055034页

作者： Gomez, B. J. Repetto, C. E. Stia, C. R. Welti, R. UNR CONICET Inst Fis Rosario Rosario Santa Fe Argentina UNR Fac Ciencias Exactas Ingn & Agrimensura Escuela Formac Basica Lab Vibraciones & OndasDept Fis Rosario Santa Fe Argentina

In this paper, we study theoretically the propagation of waves in locally periodic systems. To this end, we employ a simple method based on the impedance function which is similar to the one used in the transmission line theory. Results are presented for the particular cases of mass-loaded strings arrangements. These systems are easily reproducible in laboratory of introductory and/or advanced courses of physics, and contain all the main characteristics of locally periodic media. Transmission coefficient and normal frequencies are calculated for both mono and diatomic chains, and compared with previously computed and experimental data. Moreover, we show that the corresponding eigenfunctions can be obtained easily from the knowledge of the impedance function.

关键词： impedance function locally periodic media transmission coefficient normal modes

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Fragility curves of URM buildings in aggregate considering the interaction with soil and among nearby footings

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BULLETIN OF EARTHQUAKE ENGINEERING 2025年第9期23卷 3589-3622页

作者： Zeolla, E. Brunelli, A. de Silva, F. Cattari, S. Sica, S. Univ Sannio Benevento Italy Univ Genoa Genoa Italy Univ Federico II Naples Italy

The paper examines unreinforced masonry (URM) buildings, which are common in small historic centres around the world. These buildings are often constructed in aggregate, a configuration that not only results in significant structural interaction but also interaction with and through the foundation soil. The seismic performance of an aggregate can be influenced by foundation-soil-foundation interaction (FSFI), in addition to standard soil-foundation-structure interaction (SFSI) and site effects (SE). While reliable and time-efficient approaches are available in the literature to address all these issues for standalone buildings, buildings in aggregate are frequently modelled as isolated and fixed at their base, particularly when developing fragility curves. This paper investigates the effects of SFSI and FSFI on the period and damping ratio estimates of typical URM buildings. Specifically, it examines the impact of SE, SFSI, and FSFI on the fragility curves of two aggregated URM buildings. These latter are representative of Visso, a town heavily affected by the 2016-2017 Central Italy earthquake, known for site amplification phenomena due to soft soils. Fragility curves were developed through nonlinear dynamic analyses of equivalent 3D frame models of the two archetypes, analysed under both fixed and compliant base conditions. In the latter scenario, the structural model is equipped with springs at its base, with stiffness first calibrated to account for SFSI effects and subsequently adjusted to include the additional FSFI contribution. The results indicate a higher fragility in the fixed-base model. Specifically, the ratio of the median values of the fragility curves for the compliant base model to the fixed-base model ranges from 20 to 60%. Finally, the results from the cross-interacting models exhibited slightly higher values than those considering only SFSI, suggesting a moderate impact from the additional contribution of footing-footing interaction, at least for

关键词： impedance function Soil-structure interaction Soil-foundation-structure interaction Fragility curves Masonry structures Nonlinear dynamic analyses

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On the Reduction of Radiation Damping of Dynamic Foundation on Gibson Elastic Halfspace

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SHOCK AND VIBRATION 2025年第1期2025卷

作者： Li, Hao Cheng, Xiaohui China Earthquake Adm Inst Geophys Beijing 100081 Peoples R China Tsinghua Univ Dept Civil Engn Beijing 100084 Peoples R China

For dynamic machine foundations, it is widely acknowledged that the radiation damping ratio estimated by Lysmer's analogy method is often overestimated, leading to the adoption of modifications in design codes across various nations. This study explores the underlying reasons for this overestimation, focusing on the less recognized impact of subsoil modulus variation with depth, particularly in Gibson soil. Gibson soil, characterized by a depth-dependent modulus, can significantly reduce radiation damping even in homogeneous conditions. The research employs a cone model to analyze the vertical vibration of a circular disk foundation on Gibson soil, yielding an analytical solution for the impedance function. This study establishes an analytical relationship between Gibson soil and radiation damping reduction for the first time, revealing the independent mechanism of how the modulus varies with depth. An extended cone model is proposed to overcome the complexity of the traditional Hankel transform method. This model achieves a frequency-independent closed-form solution for Gibson soil foundation impedance. Results verify that Gibson soil has a lower damping ratio than uniform soil layers, with an average reduction factor of 0.65-0.85. These findings provide a theoretical basis for revising seismic codes (GB 50699-2011) and propose a new damping calculation formula that considers the modulus gradient.

关键词： cone model dynamic foundation Gibson soil impedance function radiation damping reduction factor

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Seismic equivalent linear response of a structure by considering soil-structure interaction: Analytical and numerical analysis

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STRUCTURAL ENGINEERING AND MECHANICS 2023年第2期87卷 173-189页

作者： Lagaguine, Maroua Sbartai, Badreddine Univ Badji Mokhtar Annaba LGC Lab BP 12 Annaba 23100 Algeria Univ Badji Mokhtar Annaba LMGE Lab BP 12 Annaba 23100 Algeria

For a given structural geometry, the stiffness and damping parameters of the soil and the dynamic response of the structure may change in the face of an equivalent linear soil behavior caused by a strong earthquake. Therefore, the influence of equivalent linear soil behavior on the impedance functions form and the seismic response of the soil -structure system has been investigated. Through the substructure method, the seismic response of the selected structure was obtained by an analytical formulation based on the dynamic equilibrium of the soil -structure system modeled by an analog model with three degrees of freedom. Also, the dynamic response of the soil -structure system for a nonlinear soil behavior and for the two types of impedance function forms was also analyzed by 2D finite element modeling using ABAQUS software. The numerical results were compared with those of the analytical solution. After the investigation, the effect of soil nonlinearity clearly showed the critical role of soil stiffness loss under strong shaking, which is more complex than the linear elastic soil behavior, where the energy dissipation depends on the seismic motion amplitude and its frequency, the impedance function types, the shear modulus reduction and the damping increase. Excellent agreement between finite element analysis and analytical results has been obtained due to the reasonable representation of the model.

关键词： equivalent linear soil model impedance function seismic response soil-structure interaction (SSI) viscoelastic model

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A simplified approach to account for through-soil interaction between two adjacent shallow foundations

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BULLETIN OF EARTHQUAKE ENGINEERING 2023年第5期21卷 2503-2532页

作者： Zeolla, Enza de Silva, Filomena Sica, Stefania Univ Sannio Dept Engn Pza Roma 21 I-82100 Benevento Italy Univ Napoli Federico II Dept Civil Architectural & Environm Engn Via Claudio 21 I-80125 Naples Italy

Neighbouring buildings, even though disconnected from the structural viewpoint, may interact through the underlying soil especially when they are founded on very soft soils. Despite some pioneering studies since the early 1970's, structure-soil-structure interaction has yet to be further investigated to reveal the effects that could be exerted on both the static and dynamic response of nearby structures. The present work aims at expanding the theoretical knowledge on this phenomenon through an extensive parametric study based on a truly 3D continuum approach solved through the Flac3D finite difference software. The impedance functions of two closely-spaced shallow foundations have been numerically calculated by varying the distance between the nearby footings and the subsoil configuration (homogeneous or layered). The numerical results have elucidated important effects of cross interaction between two neighbouring foundations. The static stiffness reduces, and this effect is increasingly significant as the foundations are closer whatever the subsoil conditions are. The dynamic coefficients increase with respect to those corresponding to the single footing over halfspace. Such effect is less important for the layer-over-halfspace soil configuration, for which the dynamic coefficients are mainly affected by the frequency response of the stratum. Finally, in the realm of the sub-structure approach, a novel simplified design approach, based on group factors for closely-spaced shallow foundations, was proposed to compute the soil-foundation impedance matrix englobing the foundation-foundation interaction in addition to the soil-foundation interaction.

关键词： 3D modelling Foundation-soil-foundation interaction SSSI or CSSI impedance function Interaction coefficients

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