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Simplified design of nonlinear damper parameters and seismic responses for long-span cable-stayed bridges

《结构与土木工程前沿（英文）》 2024年 第18卷 第7期   页码 1103-1116 doi: 10.1007/s11709-024-1033-y

摘要： Viscous dampers are widely used as passive energy dissipation devices for long-span cable-stayed bridges for mitigation of seismic load-induced vibrations. However, complicated finite element (FE) modeling, together with repetitive and computationally intensive nonlinear time-history analyses (NTHAs) are generally required in conventional design methods. To streamline the preliminary design process, this paper developed a simplified longitudinal double degree of freedom model (DDFM) for single and symmetric twin-tower cable-stayed bridges. Based on the proposed simplified longitudinal DDFM, the analytical equations for the relevant mass- and stiffness-related parameters and longitudinal natural frequencies of the structure were derived by using analytical and energy methods. Modeling of the relationship between the nonlinear viscous damper parameters and the equivalent damping ratio was achieved through the equivalent linearization method. Additionally, the analytical equations of longitudinal seismic responses for long-span cable-stayed bridges with nonlinear viscous dampers were derived. Based on the developed simplified DDFM and suggested analytical equations, this paper proposed a simplified calculation framework to achieve a simplified design method of nonlinear viscous damper parameters. Moreover, the effectiveness and applicability of the developed simplified longitudinal DDFM and the proposed calculation framework were further validated through numerical analysis of a practical cable-stayed bridge. Finally, the results indicated the following. 1) For the obtained fundamental period and longitudinal stiffness, the differences between results of the simplified longitudinal DDFM and numerical analysis were only 2.05% and 1.5%, respectively. 2) Relative calculation errors of the longitudinal girder-end displacement and bending moment of the bottom tower section of the bridge obtained from the simplified longitudinal DDFM were limited to less than 25%. 3) The equivalent damping ratio of nonlinear viscous dampers and the applied loading frequency had significant effects on the longitudinal seismic responses of the bridge. Findings of this study may provide beneficial information for a design office to make a simplified preliminary design scheme to determine the appropriate nonlinear damper parameters and longitudinal seismic responses for long-span cable-stayed bridges.

关键词： cable-stayed bridges     viscous dampers     simplified analytical model     equivalent damping ratio     seismic mitigation    

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A simplified model of direct-contact heat transfer in desalination system utilizing LNG cold energy

Qingqing SHEN, Wensheng LIN, Anzhong GU, Yonglin JU

《能源前沿（英文）》 2012年 第6卷 第2期   页码 122-128 doi: 10.1007/s11708-012-0175-0

摘要： With the increasingly extensive utilization of liquefied natural gas (LNG) in China today, sustainable and effective using of LNG cold energy is becoming increasingly important. In this paper, the utilization of LNG cold energy in seawater desalination system is proposed and analyzed. In this system, the cold energy of the LNG is first transferred to a kind of refrigerant, i.e., butane, which is immiscible with water. The cold refrigerant is then directly injected into the seawater. As a result, the refrigerant droplet is continuously heated and vaporized, and in consequence some of the seawater is simultaneously frozen. The formed ice crystal contains much less salt than that in the original seawater. A simplified model of the direct-contact heat transfer in this desalination system is proposed and theoretical analyses are conducted, taking into account both energy balance and population balance. The number density distribution of two-phase bubbles, the heat transfer between the two immiscible fluids, and the temperature variation are then deduced. The influences of initial size of dispersed phase droplets, the initial temperature of continuous phase, and the volumetric heat transfer coefficient are also clarified. The calculated results are in reasonable agreement with the available experimental data of the R114/water system.

关键词： liquefied natural gas (LNG)     cold energy utilization     desalination     direct-contact heat transfer    

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Analyzing the nonlinear vibrational wave differential equation for the simplified model of Tower Cranes

M.R. AKBARI,D.D. GANJI,A.R. AHMADI,Sayyid H. Hashemi KACHAPI

《机械工程前沿（英文）》 2014年 第9卷 第1期   页码 58-70 doi: 10.1007/s11465-014-0289-7

摘要：

In the current paper, a simplified model of Tower Cranes has been presented in order to investigate and analyze the nonlinear differential equation governing on the presented system in three different cases by Algebraic Method (AGM). Comparisons have been made between AGM and Numerical Solution, and these results have been indicated that this approach is very efficient and easy so it can be applied for other nonlinear equations. It is citable that there are some valuable advantages in this way of solving differential equations and also the answer of various sets of complicated differential equations can be achieved in this manner which in the other methods, so far, they have not had acceptable solutions. The simplification of the solution procedure in Algebraic Method and its application for solving a wide variety of differential equations not only in Vibrations but also in different fields of study such as fluid mechanics, chemical engineering, etc. make AGM be a powerful and useful role model for researchers in order to solve complicated nonlinear differential equations.

关键词： Algebraic Method (AGM)     tower crane     oscillating system     angular frequency    

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Evaluation of a developed bypass viscous damper performance

Mahrad FAHIMINIA, Aydin SHISHEGARAN

《结构与土木工程前沿（英文）》 2020年 第14卷 第3期   页码 773-791 doi: 10.1007/s11709-020-0627-2

摘要： In this study, the dynamic behavior of a developed bypass viscous damper is evaluated. Bypass viscous damper has a flexible hose as an external orifice through which the inside fluid transfer from one side to the other side of the inner piston. Accordingly, the viscosity coefficient of the damper can be adjusted using geometrical dimensions of the hose. Moreover, the external orifice acts as a thermal compensator and alleviates viscous heating of the damper. According to experimental results, Computational Fluid Dynamic (CFD) model, a numerical formula and the simplified Maxwell model are found and assessed; therefore, the verification of numerical and computational models are evaluated for simulating. Also, a simplified procedure is proposed to design structures with bypass viscous dampers. The design procedure is applied to design an 8-story hospital structure with bypass viscous dampers, and it is compared with the same structure, which is designed with concentric braces and without dampers. Nonlinear time history analyses revealed that the hospital with viscous damper experiences less structural inelastic demands and fewer story accelerations which mean fewer demands on nonstructural elements. Moreover, seismic behaviors of nonstructural masonry claddings are also compared in the cases of hospital structure with and without dampers.

关键词： developed viscous damper     external orifice     energy dissipation     seismic behavior     CFD model of viscous damper     a simplified model    

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Development of a simplified n-heptane/methane model for high-pressure direct-injection natural

Jingrui LI, Haifeng LIU, Xinlei LIU, Ying YE, Hu WANG, Xinyan WANG, Hua ZHAO, Mingfa YAO

《能源前沿（英文）》 2021年 第15卷 第2期   页码 405-420 doi: 10.1007/s11708-021-0718-3

摘要： High-pressure direct-injection (HPDI) of natu-ral gas is one of the most promising solutions for future ship engines, in which the combustion process is mainly controlled by the chemical kinetics. However, the employment of detailed chemical models for the multi-dimensional combustion simulation is significantly expensive due to the large scale of the marine engine. In the present paper, a reduced -heptane/methane model consisting of 35-step reactions was constructed using multiple reduction approaches. Then this model was further reduced to include only 27 reactions by utilizing the HyChem (Hybrid Chemistry) method. An overall good agreement with the experimentally measured ignition delay data of both -heptane and methane for these two reduced models was achieved and reasonable predictions for the measured laminar flame speeds were obtained for the 35-step model. But the 27-step model cannot predict the laminar flame speed very well. In addition, these two reduced models were both able to reproduce the experimentally measured in-cylinder pressure and heat release rate profiles for a HPDI natural gas marine engine, the highest error of predicted combustion phase being 6.5%. However, the engine-out CO emission was over-predicted and the highest error of predicted NO emission was less than 12.9%. The predicted distributions of temperature and equivalence ratio by the 35-step and 27-step models are similar to those of the 334-step model. However, the predicted distributions of OH and CH O are significantly different from those of the 334-step model. In short, the reduced chemical kinetic models developed provide a high-efficient and dependable method to simulate the characteristics of combustion and emissions in HPDI natural gas marine engines.

关键词： high-pressure direct-injection     natural gas     chemical kinetics     combustion modelling     marine engine    

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A simplified method for investigating the bending behavior of piles supporting embankments on soft ground

《结构与土木工程前沿（英文）》 2023年 第17卷 第7期   页码 1021-1032 doi: 10.1007/s11709-023-0952-3

摘要： In recent years, concrete and reinforced concrete piles have been widely used to stabilize soft ground under embankments. Previous research has shown that bending failure, particularly during rapid filling on soft ground, is the critical failure mode for pile-supported embankments. Here, we propose an efficient two-stage method that combines a test-verified soil deformation mechanism and Poulos’ solution for pile–soil interaction to investigate the bending behavior of piles supporting embankments on soft ground. The results reveal that there are three possible bending failure scenarios for such piles: at the interface between the soft and firm ground layers, at mid-depths of the fan zone, and at the boundary of the soil deformation mechanism. The location of the bending failure depends on the position and relative stiffness of the given pile. Furthermore, the effect of embedding a pile into a firm ground layer on the bending behavior was investigated. When the embedded length of a pile exceeded a critical value, the bending moment at the interface between the soft and firm ground layers reached a limiting value. In addition, floating piles that are not embedded exhibit an overturning pattern of movement in the soft ground layer, and a potential failure is located in the upper part of these piles.

关键词： bending behavior     pile     embankment     soil−structure interaction     failure mode    

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A 3D sliced-soil–beam model for settlement prediction of tunnelling using the pipe roofing method in

《结构与土木工程前沿（英文）》 2023年 第17卷 第12期   页码 1934-1948 doi: 10.1007/s11709-023-0038-2

摘要： The pipe roofing method is widely used in tunnel construction because it can realize a flexible section shape and a large section area of the tunnel, especially under good ground conditions. However, the pipe roofing method has rarely been applied in soft ground, where the prediction and control of the ground settlement play important roles. This study proposes a sliced-soil–beam (SSB) model to predict the settlement of ground due to tunnelling using the pipe roofing method in soft ground. The model comprises a sliced-soil module based on the virtual work principle and a beam module based on structural mechanics. As part of this work, the Peck formula was modified for a square-section tunnel and adopted to construct a deformation mechanism of soft ground. The pipe roofing system was simplified to a three-dimensional Winkler beam to consider the interaction between the soil and pipe roofing. The model was verified in a case study conducted in Shanghai, China, in which it provided the efficient and accurate prediction of settlement. Finally, the parameters affecting the ground settlement were analyzed. It was clarified that the stiffness of the excavated soil and the steel support are the key factors in reducing ground settlement.

关键词： pipe roofing method     soft ground     numerical simulation     settlement prediction     simplified calculation     parametric analysis    

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Improvement of aerodynamic stability of suspension bridges with H-shaped simplified stiffening girder

Hiroshi KATSUCHI,Hitoshi YAMADA,Mayuko NISHIO,Yoko OKAZAKI

《结构与土木工程前沿（英文）》 2016年 第10卷 第1期   页码 93-102 doi: 10.1007/s11709-015-0311-0

摘要： Wind-tunnel study on the improvement of aerodynamic stability of simplified suspension-bridge girder structures was conducted with using a 1/40-scaled section model. Objective of the study is the development of an economically superior suspension bridge with 500–1,000 m center span length. The wind-tunnel test showed that an edge-girder type cross section exhibited large amplitude torsional vortex-induced vibration as well as torsional flutter at a low wind speed. Accordingly, aerodynamic countermeasures of open grating deck and triangular faring, and structural countermeasures of center stay, diagonal bracing and mass increase were tried to improve the aerodynamic stability. Finally, feasibility of the best combination to a full-scale bridge was examined by structural analysis.

关键词： suspension bridge     aerodynamics     simplified girder     wind-tunnel test    

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Oscillation frequency of simplified arterial tubes

Hui AN, Fan HE, Lingxia XING, Xiaoyang LI

《机械工程前沿（英文）》 2009年 第4卷 第3期   页码 300-304 doi: 10.1007/s11465-009-0038-5

摘要： To construct the spatial kinetic equation of an arterial tube and obtain its radial natural frequency, a linear-elastic and small deformation condition is assumed. The theoretical analysis is first presented and the finite element method is then used to numerically simulate the spatial kinematics. The results show that the first-order frequency is 15.8 Hz and the obtained exact analytical solutions agree well with numerical solutions, which proves that the theoretical analysis and numerical simulation are both correct.

关键词： spatial kinematics     natural frequency     finite element method    

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用于预测涡振稳态振幅的箱梁竖向涡激力简化非线性模型

朱乐东, 孟晓亮, 杜林清, 丁明畅

《工程（英文）》 2017年 第3卷 第6期   页码 854-862 doi: 10.1016/j.eng.2017.06.001

摘要：
采用同步测力测振大比例节段模型风洞试验方法，研究了作用在全封闭、半封闭和中央开槽三种典型箱梁上竖向涡激力的非线性特性，通过分析竖向涡激力不同成分的能量演化规律和对涡振响应的贡献，探索了竖向涡激共振的起振、发展和自限幅的机理。结果显示：不同类型箱梁的竖向涡激力的非线性成分通常会有所不同，但控制竖向涡激振动稳态响应幅值的最重要涡激力成分都是速度一次线性和三次非线性气动阻尼力成分。前者向振动系统提供了一个恒定的负气动阻尼比，因而是驱动涡振振幅发展的根本动力，而后者则向系统提供了一个与涡振速度平方成正比的正气动阻尼比，从而实质上成为导致涡振自限幅现象的内在因素。有鉴于此，本文提出了一个能高精度预测大跨度桥梁涡振稳态振幅的箱梁断面竖向涡激力通用简化非线性数学模型，并进行了验证。

关键词： 箱形桥梁     竖向涡激振动     竖向涡激力     简化非线性模型     风洞试验     大比例节段模型     同步测力测振    

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A fast antibiotic detection method for simplified pretreatment through spectra-based machine learning

《环境科学与工程前沿（英文）》 2022年 第16卷 第3期 doi: 10.1007/s11783-021-1472-9

摘要：

• A spectral machine learning approach is proposed for predicting mixed antibiotic.

关键词： Antibiotic contamination     Spectral detection     Machine learning    

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Simplified theoretical analysis and numerical study on the dynamic behavior of FCP under blast loads

Chunfeng ZHAO, Xin YE, Avinash GAUTAM, Xin LU, Y. L. MO

《结构与土木工程前沿（英文）》 2020年 第14卷 第4期   页码 983-997 doi: 10.1007/s11709-020-0633-4

摘要： Precast concrete structures have developed rapidly in the last decades due to the advantages of better quality, non-pollution and fast construction with respect to conventional cast-in-place structures. In the present study, a theoretical model and nonlinear 3D model are developed and established to assess the dynamic behavior of precast concrete slabs under blast load. At first, the 3D model is validated by an experiment performed by other researchers. The verified model is adopted to investigate the blast performance of fabricated concrete panels (FCPs) in terms of parameters of the explosive charge, panel thickness, and reinforcement ratio. Finally, a simplified theoretical model of the FCP under blast load is developed to predict the maximum deflection. It is indicated that the theoretical model can precisely predict the maximum displacement of FCP under blast loads. The results show that the failure modes of the panels varied from bending failure to shear failure with the mass of TNT increasing. The thickness of the panel, reinforcement ratio, and explosive charges have significant effects on the anti-blast capacity of the FCPs.

关键词： precast structure     fabricated concrete panel     blast resistance     theory model     empirical equation    

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精简指令集架构加速芯片研发

Chris Palmer

《工程（英文）》 2022年 第17卷 第10期   页码 7-9 doi: 10.1016/j.eng.2022.08.003

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A simplified method for the determination of vertically loaded pile-soil interface parameters in layered

Jiu-jiang WU,Yan LI,Qian-gong CHENG,Hua WEN,Xin LIANG

《结构与土木工程前沿（英文）》 2016年 第10卷 第1期   页码 103-111 doi: 10.1007/s11709-015-0328-4

摘要： The numerical analysis of pile-soil interaction commonly requires a lot of trial works to determine the interface parameters and the accuracy cannot be ensured normally. Considering this, this paper first conducts a sensitivity analysis to figure out the influence of interface parameters on the bearing behavior of a single pile in sand. Then, a simplified method for the determination of pile-soil interface parameters in layered soil is proposed based on the parameter studies. Finally, a filed loading test is used for the validation of the simplified method, and the calculated results agree well with the monitoring data. In general, the simplified method proposed in this paper works with higher accuracy and consumes less time compared with the traditional trial works, especially on the determinations of interfacial cohesive and interfacial friction angle.

关键词： determination of interface parameters     pile-soil interaction     FLAC3D     sensitivity analysis     layered soil    

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Simplified seismic scenario analysis of existing masonry buildings accounting for local site effects

《结构与土木工程前沿（英文）》 2024年 第18卷 第2期   页码 309-318 doi: 10.1007/s11709-024-0982-5

摘要： This study discusses the effects of local sites and hazard amplification on the seismic vulnerability assessment of existing masonry buildings. In this context, a rapid seismic evaluation procedure was implemented on an old masonry building stock in the historical center Galata, located in İstanbul, to determine the seismic risk priority of the built heritage. Damage scenarios were generated for all soil classes, different moment magnitudes, and source-to-site distances to obtain more accurate results for the seismic vulnerability assessment of the studied building stock. Consequently, damage distributions estimated under nine different scenarios with/without site effects were compared and illustrated in maps to discuss changes in vulnerability owing to amplification effects. In this study, by re-examining the rapid seismic evaluation procedure by including geo-hazard-based assessment, the importance of site effects on the vulnerability and risk assessment of built heritage was underlined. The proposed framework integrating field data and local site effects is believed to advance the current applications for vulnerability assessment of masonry buildings and provide an improvement in the application of rapid seismic assessment procedures with more reliable results.

关键词： masonry buildings     seismic vulnerability assessment     cultural heritage     local site effect    

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标题 作者 时间 类型 操作

Simplified design of nonlinear damper parameters and seismic responses for long-span cable-stayed bridges

期刊论文

A simplified model of direct-contact heat transfer in desalination system utilizing LNG cold energy

Qingqing SHEN, Wensheng LIN, Anzhong GU, Yonglin JU

期刊论文

Analyzing the nonlinear vibrational wave differential equation for the simplified model of Tower Cranes

M.R. AKBARI,D.D. GANJI,A.R. AHMADI,Sayyid H. Hashemi KACHAPI

期刊论文

Evaluation of a developed bypass viscous damper performance

Mahrad FAHIMINIA, Aydin SHISHEGARAN

期刊论文

Development of a simplified n-heptane/methane model for high-pressure direct-injection natural

Jingrui LI, Haifeng LIU, Xinlei LIU, Ying YE, Hu WANG, Xinyan WANG, Hua ZHAO, Mingfa YAO

期刊论文

A simplified method for investigating the bending behavior of piles supporting embankments on soft ground

期刊论文

A 3D sliced-soil–beam model for settlement prediction of tunnelling using the pipe roofing method in

期刊论文

Improvement of aerodynamic stability of suspension bridges with H-shaped simplified stiffening girder

Hiroshi KATSUCHI,Hitoshi YAMADA,Mayuko NISHIO,Yoko OKAZAKI

期刊论文

Oscillation frequency of simplified arterial tubes

Hui AN, Fan HE, Lingxia XING, Xiaoyang LI

期刊论文

用于预测涡振稳态振幅的箱梁竖向涡激力简化非线性模型

朱乐东, 孟晓亮, 杜林清, 丁明畅

期刊论文

A fast antibiotic detection method for simplified pretreatment through spectra-based machine learning

期刊论文

Simplified theoretical analysis and numerical study on the dynamic behavior of FCP under blast loads

Chunfeng ZHAO, Xin YE, Avinash GAUTAM, Xin LU, Y. L. MO

期刊论文

精简指令集架构加速芯片研发

Chris Palmer

期刊论文

A simplified method for the determination of vertically loaded pile-soil interface parameters in layered

Jiu-jiang WU,Yan LI,Qian-gong CHENG,Hua WEN,Xin LIANG

期刊论文

Simplified seismic scenario analysis of existing masonry buildings accounting for local site effects

期刊论文