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Regional seismic-damage prediction of buildings under mainshock–aftershock sequence

Xinzheng LU, Qingle CHENG, Zhen XU, Chen XIONG

《工程管理前沿（英文）》 2021年 第8卷 第1期   页码 122-134 doi: 10.1007/s42524-019-0072-x

摘要： Strong aftershocks generally occur following a significant earthquake. Aftershocks further damage buildings weakened by mainshocks. Thus, the accurate and efficient prediction of aftershock-induced damage to buildings on a regional scale is crucial for decision making for post-earthquake rescue and emergency response. A framework to predict regional seismic damage of buildings under a mainshock–aftershock (MS–AS) sequence is proposed in this study based on city-scale nonlinear time-history analysis (THA). Specifically, an MS–AS sequence-generation method is proposed to generate a potential MS–AS sequence that can account for the amplification, spectrum, duration, magnitude, and site condition of a target area. Moreover, city-scale nonlinear THA is adopted to predict building seismic damage subjected to MS–AS sequences. The accuracy and reliability of city-scale nonlinear THA for an MS–AS sequence are validated by as-recorded seismic responses of buildings and simulation results in published literature. The town of Longtoushan, which was damaged during the Ludian earthquake, is used as a case study to illustrate the detailed procedure and advantages of the proposed framework. The primary conclusions are as follows. (1) Regional seismic damage of buildings under an MS–AS sequence can be predicted reasonably and accurately by city-scale nonlinear THA. (2) An MS–AS sequence can be generated reasonably by the proposed MS–AS sequence-generation method. (3) Regional seismic damage of buildings under different MS–AS scenarios can be provided efficiently by the proposed framework, which in turn can provide a useful reference for earthquake emergency response and scientific decision making for earthquake disaster relief.

关键词： regional seismic damage prediction     city-scale nonlinear time-history analysis     mainshock–aftershock sequence     multiple degree-of-freedom (MDOF) model     2014 Ludian earthquake    

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Experimental and numerical investigations of the compressive behavior of carbon fiber-reinforced polymer-strengthened tubular steel T-joints

Peng DENG, Boyi YANG, Xiulong CHEN, Yan LIU

《结构与土木工程前沿（英文）》 2020年 第14卷 第5期   页码 1215-1231 doi: 10.1007/s11709-020-0663-y

摘要： A method for strengthening damaged tubular steel T-joints under axial compression by wrapping them with carbon fiber-reinforced polymer (CFRP) sheets was proposed and evaluated. The influence of the CFRP strengthening on the failure mode and load capacity of T-joints with different degrees of damage was investigated using experiments and finite element analyses. Five T-joints were physically tested: one bare joint to obtain the peak load and corresponding displacement ( ), two reinforced joints to provide a reference, and two pre-damaged then retrofitted joints to serve as the primary research objects. The ratio of the pre-loaded specimen chord displacement to the value of was considered to be the degree of damage of the two retrofitted joints, and was set to 0.80 and 1.20. The results demonstrate that the maximum capacity of the retrofitted specimen was increased by 0.83%–15.06% over the corresponding unreinforced specimens. However, the capacity of the retrofitted specimen was 2.51%–22.77% lesser compared with that of the directly reinforced specimens. Next, 111 numerical analysis models (0.63≤ ≤0.76, 9.70≤ ≤16.92) were established to parametrically evaluate the effects of different geometric and strengthening parameters on the load capacity of strengthened tubular T-joints under different degrees of damage. The numerical analysis results revealed that the development of equivalent plastic strain at the selected measuring points was moderated by strengthening with CFRP wrapping, and indicated the optimal CFRP strengthening thickness and wrapping orientation according to tubular T-joint parameters. Finally, reasonable equations for calculating the load capacity of CFRP-strengthened joints were proposed and demonstrated to provide accurate results. The findings of this study can be used to inform improved CFRP strengthening of damaged tubular steel structures.

关键词： tubular T-joint     carbon fiber-reinforced polymer     degree of damage     numerical analysis     equivalent plastic strain    

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Analysis of synergy degree and its influencing factors in hydropower EPC project management

Jiwei ZHU, Hua GAO, Jiangrui WANG

《工程管理前沿（英文）》 2021年 第8卷 第3期   页码 402-411 doi: 10.1007/s42524-020-0098-0

摘要： The use of engineering procurement construction (EPC) mode is currently a trend in hydropower engineering construction. The clarification of the internal relationship between hydropower EPC projects and the realization of synergy has great significance in improving management efficiency and implementation effect. In this work, a three-dimensional system and a system model of hydropower EPC project management synergy are constructed. The mechanism and factors that influence the degree of management synergy are analyzed on the basis of management synergy theory. Furthermore, the evaluation index system and the degree of synergy model are established, and grey relational analysis is utilized to identify the key factors that affect the synergy degree. Thus, this study aims to facilitate the hydropower EPC project management synergy, provide a quantitative method for synergy degree evaluation, and propose corresponding promotion strategies. Results show that the order degree of each subsystem presents a steady upward trend. Specifically, the order degree of the subsystem at the trial operation stage is low, which is the major restriction on the further improvement of the synergy degree of EPC project management. The key factors in improving the synergy level of hydropower EPC project management are mainly concentrated in the information and organization synergy subsystems, including the construction degree of information platform, the performance of functions, the timeliness of information transfer, and the functions of the information platform.

关键词： hydropower project     EPC mode     synergy degree model     grey relational analysis    

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On the location of the secondary instantaneous poles in two-degree-of-freedom spherical mechanisms

Soheil ZARKANDI

《机械工程前沿（英文）》 2014年 第9卷 第1期   页码 34-40 doi: 10.1007/s11465-014-0290-1

摘要：

As the instant centers in planar mechanisms, the instantaneous poles (or instant poles, in brief) can be used for kinematic analysis in spherical mechanisms. One of the mandatory steps in this analysis is the determination of the location of these poles. This paper presents a theorem showing analytically that the locus of an unknown secondary instant pole in two-degree-of-freedom (2-DOF) spherical mechanisms is a great circle (GC). The exact location of the pole on its GC is obtained based on the configuration of the mechanism and velocity ratio of the two inputs. Moreover, using the results of the theorem, a geometrical technique is presented to determine the GC of the pole.

关键词： spherical mechanisms     instantaneous poles     great circle     angular velocity    

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Stiffness of a 3-degree of freedom translational parallel kinematic machine

null

《机械工程前沿（英文）》 2014年 第9卷 第3期   页码 233-241 doi: 10.1007/s11465-014-0312-z

摘要：

In this paper, a typical 3-degree of freedom (3-DOF) translational parallel kinematic machine (PKM) is studied and analyzed whose tool platform has only translations along X-, Y- and Z-axes. It consists of three limbs, each of which have arm and forearm with prismatic-revolute-revolute-revolute (PRRR) joints. Inverse kinematics analysis is carried out to find the slider coordinates and joint angles for a given position of tool platform. Stiffness modeling is done based on the compliance matrices of arm and forearm of each limb. Using the stiffness modeling the variations of minimum and maximum translational stiffness in the workspace are analyzed. For various architectural parameters of the 3-DOF PKM the tendency of variations on the minimum and maximum stiffness over the entire workspace is studied; and also the deflections of the tool platform along X, Y, and Z directions with respect to various forces are presented.

关键词： 3-DOF translational PKM     inverse kinematics     stiffness modeling     translational stiffness    

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Windborne debris damage prediction analysis

Fangfang SONG, Jinping OU,

《结构与土木工程前沿（英文）》 2010年 第4卷 第3期   页码 326-330 doi: 10.1007/s11709-010-0067-5

摘要： Windborne debris is one of the most important causes of the envelop destruction according to the post-damage investigations. The problem of windborne debris damage could be summarized as three parts, including windborne debris risk analysis, debris flying trajectories, and impact resistance of envelope analysis. The method of debris distribution is developed. The flying trajectories of compact and plate-like debris are solved by using a numerical method according to the different aerodynamic characteristics. The impact resistance of the envelopes is also analyzed. Besides, the process of windborne debris damage analysis is described in detail. An example of industrial building is given to demonstrate the whole method by using the observed data of typhoon Chanchu (2006). The method developed in this paper could be applied to risk assessment of windborne debris for structures in wind hazard.

关键词： typhoon     windborne debris     structural envelopes     damage estimation    

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Corrosion damage assessment and monitoring of large steel space structures

Bo CHEN, You-Lin XU, Weilian QU,

《结构与土木工程前沿（英文）》 2010年 第4卷 第3期   页码 354-369 doi: 10.1007/s11709-010-0088-0

摘要： Large steel space structures, when exposed to a harsh corrosive environment, are inevitably subjected to atmospheric corrosion and stress corrosion cracking. This paper proposes a framework for assessing the corrosion damage of large steel space structures subjected to both stress corrosion cracking and atmospheric corrosion. The empirical model for estimating atmospheric corrosion based on measured information is briefly introduced. The proposed framework is applied to a real large steel space structure built in the southern coastal area in China to assess its corrosion damage and investigate the effects of atmospheric corrosion on stress corrosion cracking. Based on the results, the conceptual design of the corrosion monitoring system of large steel space structures is finally conducted as the first step for a real corrosion monitoring system.

关键词： large steel space structure     atmospheric corrosion     stress corrosion cracking     corrosion damage     damage assessment     monitoring system    

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A survey of instantaneous poles for a class of two-degree-of-freedom spherical mechanisms

Soheil ZARKANDI

《机械工程前沿（英文）》 2014年 第9卷 第4期   页码 344-353 doi: 10.1007/s11465-014-0320-z

摘要：

This paper is a detailed exploration of instantaneous poles for a class of two-degree-of-freedom (two-DOF) spherical mechanisms (SMs) with seven links or bars. For two-DOF SMs, the secondary instantaneous poles (the ones which cannot be found by direct inspection) must lie on the specified great circles. For many of these mechanisms, however, some of these great circles cannot be obtained by a direct application of Aronhold-Kennedy theorem. This paper presents geometrical and analytical techniques to locate these unknown great circles for three topologies of seven-bar two-DOF SMs.

关键词： spherical mechanisms     instantaneous poles     Aronhold-Kennedy theorem     great circles     pencil of meridian    

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Detection of damage locations and damage steps in pile foundations using acoustic emissions with deep

Alipujiang JIERULA, Tae-Min OH, Shuhong WANG, Joon-Hyun LEE, Hyunwoo KIM, Jong-Won LEE

《结构与土木工程前沿（英文）》 2021年 第15卷 第2期   页码 318-332 doi: 10.1007/s11709-021-0715-y

摘要： The aim of this study is to propose a new detection method for determining the damage locations in pile foundations based on deep learning using acoustic emission data. First, the damage location is simulated using a back propagation neural network deep learning model with an acoustic emission data set acquired from pile hit experiments. In particular, the damage location is identified using two parameters: the pile location ( ) and the distance from the pile cap ( ). This study investigates the influences of various acoustic emission parameters, numbers of sensors, sensor installation locations, and the time difference on the prediction accuracy of and . In addition, correlations between the damage location and acoustic emission parameters are investigated. Second, the damage step condition is determined using a classification model with an acoustic emission data set acquired from uniaxial compressive strength experiments. Finally, a new damage detection and evaluation method for pile foundations is proposed. This new method is capable of continuously detecting and evaluating the damage of pile foundations in service.

关键词： pile foundations     damage location     acoustic emission     deep learning     damage step    

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Creep life assessment of aero-engine recuperator based on continuum damage mechanics approach

《机械工程前沿（英文）》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0702-6

摘要： The creep life of an aeroengine recuperator is investigated in terms of continuum damage mechanics by using finite element simulations. The effects of the manifold wall thickness and creep properties of brazing filler metal on the operating life of the recuperator are analyzed. Results show that the crack initiates from the brazing filler metal located on the outer surface of the manifold with the wall thickness of 2 mm and propagates throughout the whole region of the brazing filler metal when the creep time reaches 34900 h. The creep life of the recuperator meets the requirement of 40000 h continuous operation when the wall thickness increases to 3.5 mm, but its total weight increases by 15%. Decreasing the minimum creep strain rate with the enhancement of the creep strength of the brazing filler metal presents an obvious effect on the creep life of the recuperator. At the same stress level, the creep rupture time of the recuperator is enhanced by 13 times if the mismatch between the minimum creep rate of the filler and base metal is reduced by 20%.

关键词： creep     life assessment     brazed joint     continuum damage mechanics     aeroengine recuperator    

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Error analysis and optimization of a 3-degree of freedom translational Parallel Kinematic Machine

null

《机械工程前沿（英文）》 2014年 第9卷 第2期   页码 120-129 doi: 10.1007/s11465-014-0300-3

摘要：

In this paper, error modeling and analysis of a typical 3-degree of freedom translational Parallel Kinematic Machine is presented. This mechanism provides translational motion along the Cartesian X-, Y- and Z- axes. It consists of three limbs each having an arm and forearm with prismatic-revolute-revolute-revolute joints. The moving or tool platform maintains same orientation in the entire workspace due to its joint arrangement. From inverse kinematics, the joint angles for a given position of tool platform necessary for the error modeling and analysis are obtained. Error modeling is done based on the differentiation of the inverse kinematic equations. Variation of pose errors along X, Y and Z directions for a set of dimensions of the parallel kinematic machine is presented. A non-dimensional performance index, namely, global error transformation index is used to study the influence of dimensions and its corresponding global maximum pose error is reported. An attempt is made to find the optimal dimensions of the Parallel Kinematic Machine using Genetic Algorithms in MATLAB. The methodology presented and the results obtained are useful for predicting the performance capability of the Parallel Kinematic Machine under study.

关键词： translational Parallel Kinematic Machine     error modeling     global error transformation index    

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Bacterial inactivation, DNA damage, and faster ATP degradation induced by ultraviolet disinfection

Chao Yang, Wenjun Sun, Xiuwei Ao

《环境科学与工程前沿（英文）》 2020年 第14卷 第1期 doi: 10.1007/s11783-019-1192-6

摘要： • Long amplicon is more effective to test DNA damage induced by UV. • ATP in bacteria does not degrade instantly but does eventually after UV exposure. • After medium pressure UV exposure, ATP degraded faster. The efficacy of ultraviolet (UV) disinfection has been validated in numerous studies by using culture-based methods. However, the discovery of viable but non-culturable bacteria has necessitated the investigation of UV disinfection based on bacterial viability parameters. We used quantitative polymerase chain reaction (qPCR) to investigate DNA damage and evaluated adenosine triphosphate (ATP) to indicate bacterial viability. The results of qPCR effectively showed the DNA damage induced by UV when using longer gene amplicons, in that sufficiently long amplicons of both 16S and gadA indicated that the UV induced DNA damages. The copy concentrations of the long amplicons of 16S and gadA decreased by 2.38 log/mL and 1.88 log/mL, respectively, after exposure to 40 mJ/cm2 low-pressure UV. After UV exposure, the ATP level in the bacteria did not decrease instantly. Instead it decreased gradually at a rate that was positively related to the UV fluence. For low-pressure UV, this rate of decrease was slow, but for medium pressure UV, this rate of decrease was relatively high when the UV fluence reached 40 mJ/cm2. At the same UV fluence, the ATP level in the bacteria decreased at a faster rate after exposure to medium-pressure UV.

关键词： UV disinfection     DNA damage     qPCR     ATP    

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The damage evolution behavior of polypropylene fiber reinforced concrete subjected to sulfate attack

Ninghui LIANG; Jinwang MAO; Ru YAN; Xinrong LIU; Xiaohan ZHOU

《结构与土木工程前沿（英文）》 2022年 第16卷 第3期   页码 316-328 doi: 10.1007/s11709-022-0810-8

摘要： To study the damage evolution behavior of polypropylene fiber reinforced concrete (PFRC) subjected to sulfate attack, a uniaxial compression test was carried out based on acoustic emission (AE). The effect of sulfate attack relative to time and fiber hybridization were analyzed and the compression damage factor was calculated using a mathematical model. The changes to AE ringing counts during the compression could be divided into compaction, elastic, and AE signal hyperactivity stages. In the initial stage of sulfate attack, the concrete micropores and microcracks were compacted gradually under external load and a corrosion products filling effect, and this corresponded with detection of few AE signals and with concrete compression strength enhancement. With increasing sulfate attack time, AE activity decreased. The cumulative AE ringing counts of PFRC at all corrosion ages were much higher than those for plain concrete. PFRC could still produce AE signals after peak load due to drawing effect of polypropylene fiber. After 150 d of sulfate attack, the cumulative AE ringing counts of plain concrete went down by about an order of magnitude, while that for PFRC remained at a high level. The initial damage factor of hybrid PFRC was −0.042 and −0.056 respectively after 150 d of corrosion, indicating that the advantage of hybrid polypropylene fiber was more obvious than plain concrete and single-doped PFRC. Based on a deterioration equation, the corrosion resistance coefficient of hybrid PFRC would be less than 0.75 after 42 drying−wetting sulfate attack cycles, which was 40% longer than that of plain concrete.

关键词： polypropylene fiber reinforced concrete     sulfate attack     damage evolution behavior     acoustic emission     damage factor    

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煤炭高效洁净化利用的研究

陈吟颖,王淑娟,陈昌和,徐旭常

《中国工程科学》 2011年 第13卷 第6期   页码 51-56

摘要：

通过分析我国目前煤炭利用的主要方式和存在的问题，分析对比国内外煤炭高效洁净化利用技术，研究高效洁净化利用技术对环境的影响程度，建立了煤炭高效洁净化利用指标体系，给出了评价煤炭高效洁净化利用程度的洁净化度、生态优化度、低碳度的概念并作出了相应的定量判据，最后提出了我国2030年、2050年煤炭高效洁净化利用的有效途径和发展战略。

关键词： 洁净煤发电     洁净化度     能源可持续发展综合指标     生态优化度     低碳度    

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高饱和土固结及饱和度对土体固结的影响

金志高

《中国工程科学》 2004年 第6卷 第9期   页码 73-76

摘要：

以Terzaghi土体固结理论和Biot固结理论为基础，按饱和度不同的分类，研究了高饱和土固结机理及过程，深入分析了高饱和土饱和度变化对孔隙流体压缩性的影响，以及由此影响到高饱和土的固结全过程。

关键词： 固结     饱和度     体变模量     压缩    

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标题 作者 时间 类型 操作

Regional seismic-damage prediction of buildings under mainshock–aftershock sequence

Xinzheng LU, Qingle CHENG, Zhen XU, Chen XIONG

期刊论文

Experimental and numerical investigations of the compressive behavior of carbon fiber-reinforced polymer-strengthened tubular steel T-joints

Peng DENG, Boyi YANG, Xiulong CHEN, Yan LIU

期刊论文

Analysis of synergy degree and its influencing factors in hydropower EPC project management

Jiwei ZHU, Hua GAO, Jiangrui WANG

期刊论文

On the location of the secondary instantaneous poles in two-degree-of-freedom spherical mechanisms

Soheil ZARKANDI

期刊论文

Stiffness of a 3-degree of freedom translational parallel kinematic machine

null

期刊论文

Windborne debris damage prediction analysis

Fangfang SONG, Jinping OU,

期刊论文

Corrosion damage assessment and monitoring of large steel space structures

Bo CHEN, You-Lin XU, Weilian QU,

期刊论文

A survey of instantaneous poles for a class of two-degree-of-freedom spherical mechanisms

Soheil ZARKANDI

期刊论文

Detection of damage locations and damage steps in pile foundations using acoustic emissions with deep

Alipujiang JIERULA, Tae-Min OH, Shuhong WANG, Joon-Hyun LEE, Hyunwoo KIM, Jong-Won LEE

期刊论文

Creep life assessment of aero-engine recuperator based on continuum damage mechanics approach

期刊论文

Error analysis and optimization of a 3-degree of freedom translational Parallel Kinematic Machine

null

期刊论文

Bacterial inactivation, DNA damage, and faster ATP degradation induced by ultraviolet disinfection

Chao Yang, Wenjun Sun, Xiuwei Ao

期刊论文

The damage evolution behavior of polypropylene fiber reinforced concrete subjected to sulfate attack

Ninghui LIANG; Jinwang MAO; Ru YAN; Xinrong LIU; Xiaohan ZHOU

期刊论文

煤炭高效洁净化利用的研究

陈吟颖,王淑娟,陈昌和,徐旭常

期刊论文

高饱和土固结及饱和度对土体固结的影响

金志高

期刊论文