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Estimation of composite load model with aggregate induction motor dynamic load for an isolated hybrid

Nitin Kumar SAXENA,Ashwani Kumar SHARMA

《能源前沿（英文）》 2015年 第9卷 第4期   页码 472-485 doi: 10.1007/s11708-015-0373-7

摘要： It is well recognized that the voltage stability of a power system is affected by the load model and hence, to effectively analyze the reactive power compensation of an isolated hybrid wind-diesel based power system, the loads need to be considered along with the generators in a transient analysis. This paper gives a detailed mathematical modeling to compute the reactive power response with small voltage perturbation for composite load. The composite load is a combination of the static and dynamic load model. To develop this composite load model, the exponential load is used as a static load model and induction motors (IMs) are used as a dynamic load model. To analyze the dynamics of IM load, the fifth, third and first order model of IM are formulated and compared using differential equations solver in Matlab coding. Since the decentralized areas have many small consumers which may consist large numbers of IMs of small rating, it is not realistic to model either a single large rating unit or all small rating IMs together that are placed in the system. In place of using a single large rating IM, a group of motors are considered and then the aggregate model of IM is developed using the law of energy conservation. This aggregate model is used as a dynamic load model. For different simulation studies, especially in the area of voltage stability with reactive power compensation of an isolated hybrid power system, the transfer function of the composite load is required. The transfer function of the composite load is derived in this paper by successive derivation for the exponential model of static load and for the fifth and third order IM dynamic load model using state space model.

关键词： isolated hybrid power system (IHPS)     composite load model     static load     dynamic load     induction motor load model     aggregate load    

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Dynamic analysis of composite beam subjected to harmonic moving load based on the third-order shear deformation

Mohammad Javad REZVANIL, Mohammad Hossein KARGARNOVIN, Davood YOUNESIAN

《机械工程前沿（英文）》 2011年 第6卷 第4期   页码 409-418 doi: 10.1007/s11465-011-0245-8

摘要：

The response of an infinite Timoshenko beam subjected to a harmonic moving load based on the third-order shear deformation theory (TSDT) is studied. The beam is made of laminated composite, and located on a Pasternak viscoelastic foundation. By using the principle of total minimum potential energy, the governing partial differential equations of motion are obtained. The solution is directed to compute the deflection and bending moment distribution along the length of the beam. Also, the effects of two types of composite materials, stiffness and shear layer viscosity coefficients of foundation, velocity and frequency of the moving load over the beam response are studied. In order to demonstrate the accuracy of the present method, the results TSDT are compared with the previously obtained results based on first-order shear deformation theory, with which good agreements are observed.

关键词： timoshenko composite beam     pasternak viscoelastic foundation     third-order shear deformation theory (TSDT)     harmonic moving load    

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Analysis and design of steel-concrete composite sandwich systems subjected to extreme loads

Kazi Md Abu SOHEL, Jat Yuen Richard LIEW, Min Hong ZHANG

《结构与土木工程前沿（英文）》 2011年 第5卷 第3期   页码 278-293 doi: 10.1007/s11709-011-0120-z

摘要： This paper presents the design guide based on analytical, numerical and experimental investigation of Steel-concrete-steel (SCS) sandwich structural members comprising a lightweight concrete core with density ranged from 1300 to 1445 kg/m subjected to static, impact and blast loads. The performance of lightweight sandwich members is also compared with similar members with normal weight concrete core and ultra high strength concrete core ( = 180 MPa). Novel J-hook shear connectors were invented to prevent the separation of face plates from the concrete core under extreme loads and their uses are not restricted by the concrete core thickness. Flexural and punching are the primary modes of failure under static point load. Impact test results show that the SCS sandwich panels with the J-hook connectors are capable of resisting impact load with less damage in comparison than equivalent stiffened steel plate panels. Blast tests with 100 kg TNT were performed on SCS sandwich specimens to investigate the key parameters that affect the blast resistance of SCS sandwich structure. Plastic yield line method is proposed to predict the plastic capacity and post peak large deflection of the sandwich plates. Finally, an energy balanced model is developed to analyze the global behavior of SCS sandwich panels subjected to dynamic load.

关键词： blast load     composite structure     impact load     lightweight concrete     sandwich plate     J-hook connector    

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A practical multi-lane factor model of bridges based on multi-truck presence considering lane load disparities

《结构与土木工程前沿（英文）》 2021年 第15卷 第4期   页码 877-894 doi: 10.1007/s11709-021-0756-2

摘要： Many bridge design specifications consider multi-lane factors (MLFs) a critical component of the traffic load model. Measured multi-lane traffic data generally exhibit significant lane disparities in traffic loads over multiple lanes. However, these disparities are not considered in current specifications. To address this drawback, a multi-coefficient MLF model was developed based on an improved probabilistic statistical approach that considers the presence of multiple trucks. The proposed MLF model and approach were calibrated and demonstrated through an example site. The model sensitivity analysis demonstrated the significant influence of lane disparity of truck traffic volume and truck weight distribution on the MLF. Using the proposed approach, the experimental site study yielded MLFs comparable with those directly calculated using traffic load effects. The exclusion of overloaded trucks caused the proposed approach, existing design specifications, and conventional approach of ignoring lane load disparity to generate comparable MLFs, while the MLFs based on the proposed approach were the most comprehensive. The inclusion of overloaded trucks caused the conventional approach and design specifications to overestimate the MLFs significantly. Finally, the benefits of the research results to bridge practitioners were discussed.

关键词： bridges     multi-lane factor     traffic load     lane load disparity     multi-truck presence     weigh-in-motion data    

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Shape design of arch dams under load uncertainties with robust optimization

Fengjie TAN, Tom LAHMER

《结构与土木工程前沿（英文）》 2019年 第13卷 第4期   页码 852-862 doi: 10.1007/s11709-019-0522-x

摘要： Due to an increased need in hydro-electricity, water storage, and flood protection, it is assumed that a series of new dams will be build throughout the world. The focus of this paper is on the non-probabilistic-based design of new arch-type dams by applying means of robust design optimization (RDO). This type of optimization takes into account uncertainties in the loads and in the material properties of the structure. As classical procedures of probabilistic-based optimization under uncertainties, such as RDO and reliability-based design optimization (RBDO), are in general computationally expensive and rely on estimates of the system’s response variance, we will not follow a full-probabilistic approach but work with predefined confidence levels. This leads to a bi-level optimization program where the volume of the dam is optimized under the worst combination of the uncertain parameters. As a result, robust and reliable designs are obtained and the result is independent from any assumptions on stochastic properties of the random variables in the model. The optimization of an arch-type dam is realized here by a robust optimization method under load uncertainty, where hydraulic and thermal loads are considered. The load uncertainty is modeled as an ellipsoidal expression. Comparing with any traditional deterministic optimization method, which only concerns the minimum objective value and offers a solution candidate close to limit-states, the RDO method provides a robust solution against uncertainty. To reduce the computational cost, a ranking strategy and an approximation model are further involved to do a preliminary screening. By this means, the robust design can generate an improved arch dam structure that ensures both safety and serviceability during its lifetime.

关键词： arch dam     shape optimization     robust optimization     load uncertainty     approximation model    

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Modeling oblique load carrying capacity of batter pile groups using neural network, random forest regressionand M5 model tree

Tanvi SINGH, Mahesh PAL, V. K. ARORA

《结构与土木工程前沿（英文）》 2019年 第13卷 第3期   页码 674-685 doi: 10.1007/s11709-018-0505-3

摘要： M5 model tree, random forest regression (RF) and neural network (NN) based modelling approaches were used to predict oblique load carrying capacity of batter pile groups using 247 laboratory experiments with smooth and rough pile groups. Pile length ( ), angle of oblique load ( ), sand density ( ), number of batter piles ( ), and number of vertical piles ( ) as input and oblique load ( ) as output was used. Results suggest improved performance by RF regression for both pile groups. M5 model tree provides simple linear relation which can be used for the prediction of oblique load for field data also. Model developed using RF regression approach with smooth pile group data was found to be in good agreement for rough piles data. NN based approach was found performing equally well with both smooth and rough piles. Sensitivity analysis using all three modelling approaches suggest angle of oblique load ( ) and number of batter pile ( ) affect the oblique load capacity for both smooth and rough pile groups.

关键词： batter piles     oblique load test     neural network     M5 model tree     random forest regression     ANOVA    

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New model of load transfer function for pile analysis based on disturbed state model

LIU Qijian, YANG Linde, WU Jun

《结构与土木工程前沿（英文）》 2007年 第1卷 第4期   页码 443-447 doi: 10.1007/s11709-007-0060-9

摘要： Based on the disturbed state concept (DSC), a new model of load transfer function for pile analysis is established by the idea that the deformed material between pile and soil can be treated as a mixture of two constituent parts, which are in intact or critical state and assumed to obey random distribution. Starting from the homogenization theory of heterogeneous materials and statistics method, a parameter to describe the disturbance degree is proposed, and a formula to determine the parameter has been derived by using the plastic displacement of a pile as distribution variable. In the model, shear intensity of elements in an intact state are simulated by Duncan-Zhang model and that in a critical state by Mohr-Coulomb criterion. The model of this paper has few parameters, which can reflect the aspects of load transfer function, such as hardening, softening and the effects of confining pressure. The well agreement between the in-situ data and the predicted shows that the validity of the model herein. So the proposed model in this paper is easy to be used in engineering practice.

关键词： hardening     homogenization     displacement     engineering     Duncan-Zhang    

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State identification of home appliance with transient features in residential buildings

《能源前沿（英文）》 2022年 第16卷 第1期   页码 130-143 doi: 10.1007/s11708-022-0822-z

摘要： Nonintrusive load monitoring (NILM) is crucial for extracting patterns of electricity consumption of household appliance that can guide users’ behavior in using electricity while their privacy is respected. This study proposes an online method based on the transient behavior of individual appliances as well as system steady-state characteristics to estimate the operating states of the appliances. It determines the number of states for each appliance using the density-based spatial clustering of applications with noise (DBSCAN) method and models the transition relationship among different states. The states of the working appliances are identified from aggregated power signals using the Kalman filtering method in the factorial hidden Markov model (FHMM). Thereafter, the identified states are confirmed by the verification of system states, which are the combination of the working states of individual appliances. The verification step involves comparing the total measured power consumption with the total estimated power consumption. The use of transient features can achieve fast state inference and it is suitable for online load disaggregation. The proposed method was tested on a high-resolution data set such as Labeled hIgh-Frequency daTaset for Electricity Disaggregation (LIFTED) and it outperformed other related methods in the literature.

关键词： nonintrusive load monitoring (NILM)     load disaggregation     online load disaggregation     Kalman filtering     factorial hidden Markov model (FHMM)     Labeled hIgh-Frequency daTaset for Electricity Disaggregation (LIFTED)    

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A multiscale material model for heterogeneous liquid droplets in solid soft composites

《结构与土木工程前沿（英文）》 2021年 第15卷 第5期   页码 1292-1299 doi: 10.1007/s11709-021-0771-3

摘要： Liquid droplets in solid soft composites have been attracting increasing attention in biological applications. In contrary with conventional composites, which are made of solid elastic inclusions, available material models for composites including liquid droplets are for highly idealized configurations and do not include all material real parameters. They are also all deterministic and do not address the uncertainties arising from droplet radius, volume fraction, dispersion and agglomeration. This research revisits the available models for liquid droplets in solid soft composites and presents a multiscale computational material model to determine their elastic moduli, considering nearly all relevant uncertainties and heterogeneities at different length scales. The effects of surface tension at droplets interface, their volume fraction, size, size polydispersity and agglomeration on elastic modulus, are considered. Different micromechanical material models are incorporated into the presented computational framework. The results clearly indicate both softening and stiffening effects of liquid droplets and show that the model can precisely predict the effective properties of liquid droplets in solid soft composites.

关键词： liquid in solid     soft composite     computational modeling     multiscale model     heterogeneity    

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Mean wind load induced incompatibility in nonlinear aeroelastic simulations of bridge spans

Zhitian ZHANG

《结构与土木工程前沿（英文）》 2019年 第13卷 第3期   页码 605-617 doi: 10.1007/s11709-018-0499-x

摘要： Mean wind response induced incompatibility and nonlinearity in bridge aerodynamics is discussed, where the mean wind and aeroelastic loads are applied simultaneously in time domain. A kind of incompatibility is found during the simultaneous simulation of the mean wind and aeroelastic loads, which leads to incorrect mean wind structural responses. It is found that the mathematic expectations (or limiting characteristics) of the aeroelastic models are fundamental to this kind of incompatibility. In this paper, two aeroelastic models are presented and discussed, one of indicial-function-denoted (IF-denoted) and another of rational-function-denoted (RF-denoted). It is shown that, in cases of low wind speeds, the IF-denoted model reflects correctly the mean wind load properties, and results in correct mean structural responses; in contrast, the RF-denoted model leads to incorrect mean responses due to its nonphysical mean properties. At very high wind speeds, however, even the IF-denoted model can lead to significant deviation from the correct response due to steady aerodynamic nonlinearity. To solve the incompatibility at high wind speeds, a methodology of subtraction of pseudo-steady effects from the aeroelastic model is put forward in this work. Finally, with the method presented, aeroelastic nonlinearity resulted from the mean wind response is investigated at both moderate and high wind speeds.

关键词： bridge     aerodynamics     nonlinear     aeroelastic model     Pseudo-steady     mean wind loads    

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Mechanical responses of multi-layered ground due to shallow tunneling with arbitrary ground surface load

《结构与土木工程前沿（英文）》 2023年 第17卷 第5期   页码 745-762 doi: 10.1007/s11709-023-0935-4

摘要： An analytical model based on complex variable theory is proposed to investigate ground responses due to shallow tunneling in multi-layered ground with an arbitrary ground surface load. The ground layers are assumed to be linear-elastic with full-stick contact between them. To solve the proposed multi-boundary problem, a series of analytic functions is introduced to accurately express the stresses and displacements contributed by different boundaries. Based on the principle of linear-elastic superposition, the multi-boundary problem is converted into a superposition of multiple single-boundary problems. The conformal mappings of different boundaries are independent of each other, which allows the stress and displacement fields to be obtained by the sum of components from each boundary. The analytical results are validated based on numerical and in situ monitoring results. The present model is superior to the classical model for analyzing ground responses of shallow tunneling in multi-layered ground; thus, it can be used with assurance to estimate the ground movement and surface building safety of shallow tunnel constructions beneath surface buildings. Moreover, the solution for the ground stress distribution can be used to estimate the safety of a single-layer composite ground.

关键词： analytical model     mechanical response     multi-layered ground     shallow tunneling     ground surface load     complex variable solution    

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3D finite element analysis of composite noise barrier constructed of polyurethane products

Ben DAEE,Hesham El NAGGAR

《结构与土木工程前沿（英文）》 2017年 第11卷 第1期   页码 100-110 doi: 10.1007/s11709-016-0364-8

摘要： This paper presents a numerical investigation on the structural performance of an innovative noise barrier consisting of poly-block, rigid polyurethane foam (RPF) and polyurea. The mechanical characteristics of RPF as well as the flexural resistance of the proposed wall system (poly-wall) were established and presented in another study. The experimental results are used in the current study to develop, calibrate and verify 3D finite element (FE) models of the wall system. The components of the poly-wall including steel rebars, poly-blocks and RPF cores were simulated and then verified using the results of experiments conducted on the wall components. The results of numerical analysis exhibited a satisfactory agreement with the experimental outcomes for the entire wall system. The verified numerical models were then used to conduct a parametric study on the performance of poly-wall models under uniform wind load and gravity load. The findings of the current study confirmed that the structural performance of poly-wall is satisfactory for noise barrier application. Simulation techniques for improvement of the numerical analysis of multi-martial 3D FE models were discussed.

关键词： 3D finite element     sound wall     rigid polyurethane foam     poly-wall     numerical model     calibration    

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Fatigue evaluation of steel-concrete composite deck in steel truss bridge——A case study

Huating CHEN; Xianwei ZHAN; Xiufu ZHU; Wenxue ZHANG

《结构与土木工程前沿（英文）》 2022年 第16卷 第10期   页码 1336-1350 doi: 10.1007/s11709-022-0852-y

摘要： An innovative composite deck system has recently been proposed for improved structural performance. To study the fatigue behavior of a steel-concrete composite bridge deck, we took a newly-constructed rail-cum-road steel truss bridge as a case study. The transverse stress history of the bridge deck near the main truss under the action of a standard fatigue vehicle was calculated using finite element analysis. Due to the fact that fatigue provision remains unavailable in the governing code of highway concrete bridges in China, a preliminary fatigue evaluation was conducted according to the fib Model Code. The results indicate that flexural failure of the bridge deck in the transverse negative bending moment region is the controlling fatigue failure mode. The fatigue life associated with the fatigue fracture of steel reinforcement is 56 years. However, while the top surface of the bridge deck concrete near the truss cracks after just six years, the bridge deck performs with fatigue cracks during most of its design service life. Although fatigue capacity is acceptable under design situations, overloading or understrength may increase its risk of failure. The method presented in this work can be applied to similar bridges for preliminary fatigue assessment.

关键词： Fatigue assessment     composite bridge deck     rail-cum-road bridge     fatigue stress analysis     Model Code    

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复合浇筑式钢桥面铺装车辙评估模型研究

章登精

《中国工程科学》 2013年 第15卷 第8期   页码 63-69

摘要：

根据南京长江第四大桥钢桥面铺装试验研究成果，对复合浇筑式沥青混合料性能进行了分析研究，通过系统分析动稳定度与温度、汽车轮载、车速及行车道间的关系，结合南京地区汽车超载情况的研究，提出并建立了复合浇筑式钢桥面铺装的车辙评估模型。

关键词： 复合浇筑式     钢桥面铺装     动态模量     当量轮次     车辙评估模型    

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多相复合陶瓷刀具材料的设计与制备

许崇海,艾兴

《中国工程科学》 2001年 第3卷 第3期   页码 71-74

摘要：

陶瓷材料的多相复合与计算机辅助设计是21世纪先进陶瓷材料的重要发展趋势。文章采用理论与实验相结合的方法，建立了多相复合陶瓷刀具材料力学性能与材料组分之间关系的数学模型，采用计算机辅助优 化设计技术求得材料的最优组分。在此基础上，利用热压技术制得一种Al2〇3-SiC-(W,Ti) C多相复合陶瓷刀具材料，该材料具有良好的综合力学性能。

关键词： 陶瓷刀具材料     多相复合     材料设计     模型     力学性能    

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标题 作者 时间 类型 操作

Estimation of composite load model with aggregate induction motor dynamic load for an isolated hybrid

Nitin Kumar SAXENA,Ashwani Kumar SHARMA

期刊论文

Dynamic analysis of composite beam subjected to harmonic moving load based on the third-order shear deformation

Mohammad Javad REZVANIL, Mohammad Hossein KARGARNOVIN, Davood YOUNESIAN

期刊论文

Analysis and design of steel-concrete composite sandwich systems subjected to extreme loads

Kazi Md Abu SOHEL, Jat Yuen Richard LIEW, Min Hong ZHANG

期刊论文

A practical multi-lane factor model of bridges based on multi-truck presence considering lane load disparities

期刊论文

Shape design of arch dams under load uncertainties with robust optimization

Fengjie TAN, Tom LAHMER

期刊论文

Modeling oblique load carrying capacity of batter pile groups using neural network, random forest regressionand M5 model tree

Tanvi SINGH, Mahesh PAL, V. K. ARORA

期刊论文

New model of load transfer function for pile analysis based on disturbed state model

LIU Qijian, YANG Linde, WU Jun

期刊论文

State identification of home appliance with transient features in residential buildings

期刊论文

A multiscale material model for heterogeneous liquid droplets in solid soft composites

期刊论文

Mean wind load induced incompatibility in nonlinear aeroelastic simulations of bridge spans

Zhitian ZHANG

期刊论文

Mechanical responses of multi-layered ground due to shallow tunneling with arbitrary ground surface load

期刊论文

3D finite element analysis of composite noise barrier constructed of polyurethane products

Ben DAEE,Hesham El NAGGAR

期刊论文

Fatigue evaluation of steel-concrete composite deck in steel truss bridge——A case study

Huating CHEN; Xianwei ZHAN; Xiufu ZHU; Wenxue ZHANG

期刊论文

复合浇筑式钢桥面铺装车辙评估模型研究

章登精

期刊论文

多相复合陶瓷刀具材料的设计与制备

许崇海,艾兴

期刊论文