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Effect of seismic wave propagation in massed medium on rate-dependent anisotropic damage growth in concrete

Alireza DANESHYAR, Hamid MOHAMMADNEZHAD, Mohsen GHAEMIAN

《结构与土木工程前沿(英文)》 2021年 第15卷 第2期   页码 346-363 doi: 10.1007/s11709-021-0694-z

摘要: Seismic modeling of massive structures requires special caution, as wave propagation effects significantly affect the responses. This becomes more crucial when the path-dependent behavior of the material is considered. The coexistence of these conditions renders numerical earthquake analysis of concrete dams challenging. Herein, a finite element model for a comprehensive nonlinear seismic simulation of concrete gravity dams, including realistic soil–structure interactions, is introduced. A semi-infinite medium is formulated based on the domain reduction method in conjunction with standard viscous boundaries. Accurate representation of radiation damping in a half-space medium and wave propagation effects in a massed foundation are verified using an analytical solution of vertically propagating shear waves in a viscoelastic half-space domain. A rigorous nonlinear finite element model requires a precise description of the material response. Hence, a microplane-based anisotropic damage–plastic model of concrete is formulated to reproduce irreversible deformations and tensorial degeneration of concrete in a coupled and rate-dependent manner. Finally, the Koyna concrete gravity dam is analyzed based on different assumptions of foundation, concrete response, and reservoir conditions. Comparison between responses obtained based on conventional assumptions with the results of the presented comprehensive model indicates the significance of considering radiation damping and employing a rigorous constitutive material model, which is pursued for the presented model.

关键词: soil–structure interaction     massed foundation     radiation damping     anisotropic damage    

Uncoupled state space solution to layered poroelastic medium with anisotropic permeability and compressible

Zhiyong AI, Wenze ZENG, Yichong CHENG, Chao WU

《结构与土木工程前沿(英文)》 2011年 第5卷 第2期   页码 171-179 doi: 10.1007/s11709-011-0103-0

摘要: This paper presents an uncoupled state space solution to three-dimensional consolidation of layered poroelastic medium with anisotropic permeability and compressible pore fluid. Starting from the basic equations of poroelastic medium, and introducing intermediate variables, the state space equation usually comprising eight coupled state vectors is uncoupled into two sets of equations of six and two state vectors in the Laplace-Fourier transform domain. Combined with the continuity conditions between adjacent layers and boundary conditions, the uncoupled state space solution of a layered poroelastic medium is obtained by using the transfer matrix method. Numerical results show that the anisotropy of permeability and the compressibility of pore fluid have remarkable influence on the consolidation behavior of poroelastic medium.

关键词: uncoupled state space solution     layered poroelastic medium     three-dimensional consolidation     anisotropic permeability     compressible pore fluid    

Effect of anisotropic characteristics on the mechanical behavior of asphalt concrete overlay

Lingyun YOU, Zhanping YOU, Kezhen YAN

《结构与土木工程前沿(英文)》 2019年 第13卷 第1期   页码 110-122 doi: 10.1007/s11709-018-0476-4

摘要: Asphalt concrete (AC) overlays placed over old asphalt pavement have become an alternative to repairing and reinforcing pavements. The strength contributed by the AC overlay is strongly influenced by the anisotropic properties of the pavement material. This study was conducted to analyze the influence of anisotropy, modulus gradient properties, and the condition of the AC overlay and old pavement contact plane on the mechanical behaviors of AC overlays, as well as to quantify the influence of the degree of anisotropy on the mechanical behaviors of AC overlay by a sensitivity analysis (SA). The mechanical behaviors of the AC overlay were numerically obtained using the three-dimensional finite element method with the aid of ABAQUS a commercial program. Variations in the AC overlay’s modulus as a function of temperature as well as the contact state between the AC overlay and AC layer were considered. The SA is based on standardized regression coefficients method. Comparing the mechanical behavior in terms of surface deflection, stress, and strain of the anisotropy model against those corresponding to the isotropic model under static loads show that the anisotropic properties had greater effects on the mechanical behavior of the AC overlay. In addition, the maximum shear stress in the AC overlay was the most significant output parameter affected by the degree of anisotropy. Therefore, future research concerning the reinforcement and repair of pavements should consider the anisotropic properties of the pavement materials.

关键词: asphalt concrete overlay     anisotropy     temperature gradients     modulus gradients     finite element simulation     sensitivity analysis    

Experimental study on compaction-induced anisotropic mechanical property of rockfill material

Xiangtao ZHANG, Yizhao GAO, Yuan WANG, Yu-zhen YU, Xun SUN

《结构与土木工程前沿(英文)》 2021年 第15卷 第1期   页码 109-123 doi: 10.1007/s11709-021-0693-0

摘要: The anisotropy of rockfill materials has a significant influence on the performance of engineering structures. However, relevant research data are very limited, because of the difficulty with preparing specimens with different inclination angles using traditional methods. Furthermore, the anisotropy test of rockfill materials is complex and complicated, especially for triaxial tests, in which the major principal stress plane intersects with the compaction plane at different angles. In this study, the geometric characteristics of a typical particle fraction consisting of a specific rockfill material were statistically investigated, and the distribution characteristics of particle orientation in specimens prepared via different compaction methods were examined. For high-density rockfill materials, a set of specimen preparation devices for inclined compaction planes was developed, and a series of conventional triaxial compression tests with different principal stress direction angles were conducted. The results reveal that the principal stress direction angle has a significant effect on the modulus, shear strength, and dilatancy of the compacted rockfill materials. Analysis of the relationship between the principal stress direction angles, change in the stress state, and change in the corresponding dominant shear plane shows that the angle between the compacted surface and dominant shear plane is closely related to interlocking resistance associated with the particle orientation. In addition, different principal stress direction angles can change the extent of the particle interlocking effect, causing the specimen to exhibit different degrees of anisotropy.

关键词: rockfill     inclination of specimen preparation     anisotropy     mechanical property     mechanism    

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    

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    

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    

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    

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    

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    

Spectral element modeling based structure piezoelectric impedance computation and damage identification

Zhigang GUO, Zhi SUN

《结构与土木工程前沿(英文)》 2011年 第5卷 第4期   页码 458-464 doi: 10.1007/s11709-011-0133-7

摘要: This paper presents a numerical simulation study on electromechanical impedance technique for structural damage identification. The basic principle of impedance based damage detection is structural impedance will vary with the occurrence and development of structural damage, which can be measured from electromechanical admittance curves acquired from PZT patches. Therefore, structure damage can be identified from the electromechanical admittance measurements. In this study, a model based method that can identify both location and severity of structural damage through the minimization of the deviations between structural impedance curves and numerically computed response is developed. The numerical model is set up using the spectral element method, which is promised to be of high numerical efficiency and computational accuracy in the high frequency range. An optimization procedure is then formulated to estimate the property change of structural elements from the electric admittance measurement of PZT patches. A case study on a pin-pin bar is conducted to investigate the feasibility of the proposed method. The results show that the presented method can accurately identify bar damage location and severity even when the measurements are polluted by 5% noise.

关键词: PZT     piezoelectric impedance     optimization     spectral element     damage identification    

Damage detection in beam-like structures using static shear energy redistribution

《结构与土木工程前沿(英文)》 2022年 第16卷 第12期   页码 1552-1564 doi: 10.1007/s11709-022-0903-4

摘要: In this study, a static shear energy algorithm is presented for the damage assessment of beam-like structures. According to the energy release principle, the strain energy of a damaged element suddenly changes when structural damage occurs. Therefore, the change in the static shear energy is employed to determine the damage locations in beam-like structures. The static shear energy is derived from the spectral factorization of the elementary stiffness matrix and structural deflection variation. The advantage of using shear energy as opposed to total energy is that only a few deflection data points of the beam structure are required during the process of damage identification. Another advantage of the proposed approach is that damage detection can be performed without establishing a structural finite-element model in advance. The proposed technique is first validated using a numerical example with single, multiple, and adjacent damage scenarios. A channel steel beam and rectangular concrete beam are employed as experimental cases to further verify the proposed approach. The results of the simulation and experiment examples indicate that the proposed algorithm provides a simple and effective method for defect localization in beam-like structures.

关键词: damage detection     beam structure     strain energy     static displacement variation     energy damage index    

Temperature effects of shape memory alloys (SMAs) in damage control design of steel portal frames

Xiaoqun LUO, Hanbin GE, Tsutomu USAMI

《结构与土木工程前沿(英文)》 2012年 第6卷 第4期   页码 348-357 doi: 10.1007/s11709-012-0176-4

摘要: The objective of the present study is to analytically investigate temperature effects of an axial-type seismic damper made of shape memory alloys (SMAs) equipped in steel frames. Based on a modified multilinear one dimensional constitutive model of SMAs, two types of SMAs are employed, which have different stress plateau and different stress growth rate with temperature increase. Temperature effects of SMA dampers on seismic performance upgrading are discussed in three aspects: different environment temperatures; rapid loading rate induced heat generation and different SMA fractions. The analysis indicates that the effect of environment temperature should be considered for the SMA damper in steel frames. However, the rapid loading rate induced heat generation has little adverse effect.

关键词: damage control design     shape memory alloy     temperature effect    

Numerical simulation of damage in high arch dam due to earthquake

Hong ZHONG , Gao LIN , Hongjun LI

《结构与土木工程前沿(英文)》 2009年 第3卷 第3期   页码 316-322 doi: 10.1007/s11709-009-0039-9

摘要: Based on the assumption that concrete is macroscopic homogeneous, the cracking evolution process and damage mode of high arch dams are studied in consideration of the heterogeneity of concrete in mesoscale. The bilinear damage evolution model and the damage evolution model expressed in power function with descending section are adopted to combine with the Mohr-Coulomb criterion to investigate the crack development and fracture mode of high arch dams under the action of an earthquake. The analysis result of a high arch dam in China under design shows that cracks that take place in concrete are caused by excessive tensile stress. The cracks initiate at the middle of the dam top and distribute at the upper half of the dam while the rest of the parts remain intact. This conclusion agrees with the model test result.

关键词: mesoscopic heterogeneity     damage simulation in earthquakes     arch dam    

Finite element analysis of stress concentrations and failure criteria in composite plates with circular holes

null

《机械工程前沿(英文)》 2014年 第9卷 第3期   页码 281-294 doi: 10.1007/s11465-014-0307-9

摘要:

In this study, the stress concentration factors (SCF) in cross-and-angle-ply laminated composite plates as well as in isotropic plates with single circular holes subjected to uniaxial loading is studied. A quadrilateral finite element of four-node with 32 degrees of freedom at each node, previously developed for the bending and mechanical buckling of laminated composite plates, is used to evaluate the stress distribution in laminated composite plates with central circular holes. Based up on the classical plate theory, the present finite element is a combination of a linear isoparametric membrane element and a high precision rectangular Hermitian element. The numerical results obtained by the present element compare favorably with those obtained by the analytic approaches published in literature. It is observed that the obtained results are very close to the reference results, which demonstrates the accuracy of the present element. Additionally, to determine the first ply failure (FPF) of laminated plate, several failure criterions are employed. Finally, to show the effect of ratio on the failure of plates, a number of figures are given for different fiber orientation angles.

关键词: laminated composite plates     stress concentration     geometric singularity     anisotropic effect    

标题 作者 时间 类型 操作

Effect of seismic wave propagation in massed medium on rate-dependent anisotropic damage growth in concrete

Alireza DANESHYAR, Hamid MOHAMMADNEZHAD, Mohsen GHAEMIAN

期刊论文

Uncoupled state space solution to layered poroelastic medium with anisotropic permeability and compressible

Zhiyong AI, Wenze ZENG, Yichong CHENG, Chao WU

期刊论文

Effect of anisotropic characteristics on the mechanical behavior of asphalt concrete overlay

Lingyun YOU, Zhanping YOU, Kezhen YAN

期刊论文

Experimental study on compaction-induced anisotropic mechanical property of rockfill material

Xiangtao ZHANG, Yizhao GAO, Yuan WANG, Yu-zhen YU, Xun SUN

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

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

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

Spectral element modeling based structure piezoelectric impedance computation and damage identification

Zhigang GUO, Zhi SUN

期刊论文

Damage detection in beam-like structures using static shear energy redistribution

期刊论文

Temperature effects of shape memory alloys (SMAs) in damage control design of steel portal frames

Xiaoqun LUO, Hanbin GE, Tsutomu USAMI

期刊论文

Numerical simulation of damage in high arch dam due to earthquake

Hong ZHONG , Gao LIN , Hongjun LI

期刊论文

Finite element analysis of stress concentrations and failure criteria in composite plates with circular holes

null

期刊论文