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Influence of construction-induced damage on the degradation of freeze–thawed lightweight cellular concrete

《结构与土木工程前沿（英文）》 2021年 第15卷 第3期   页码 781-792 doi: 10.1007/s11709-021-0733-9

摘要： During the construction of lightweight cellular concrete (LCC), material damage frequently occurs, causing the degradation and deterioration of the mechanical performance, durability, and subgrade quality of LCC. The construction-induced damage can be more significant than those from the service environment of LCC, such as freeze–thaw (F–T) action in cold regions. However, the effect of construction-induced damage on LCC during F–T cycles is often ignored and the deterioration mechanisms are not yet clarified. In this study, we investigated the factors causing damage during construction using a sample preparation method established to simulate the damage in the laboratory setting. We conducted F–T cycle tests and microstructural characterization to study the effect of microstructural damage on the overall strength of LCC with different water contents under F–T actions. We established the relationship between the pore-area ratio and F–T cycle times, pore-area ratio, and strength, as well as the F–T cycle times and strength under different damage forms. The damage evolution is provided with the rationality of the damage equation, verified by comparing the measured and predicted damage variables. This study would serve as a guide for the construction and performance of LCC in cold regions.

关键词： lightweight cellular concrete     construction-induced damage     freeze-thaw action     microstructure     degradation mechanism    

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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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Liquefaction-induced damage evaluation of earth embankment and corresponding countermeasure

Linlin GU; Wei ZHENG; Wenxuan ZHU; Zhen WANG; Xianzhang LING; Feng ZHANG

《结构与土木工程前沿（英文）》 2022年 第16卷 第9期   页码 1183-1195 doi: 10.1007/s11709-022-0848-7

摘要： Liquefaction of sandy soils is a big threat to the stability and the safety of an earth embankment laid on saturated soils. A large number of liquefaction-induced damages on embankment due to different types of earthquakes have been reported worldwide. In this research, the dynamic behaviors of earth embankment and the reinforcement effects of grouting as remediation method, subjected to moderate earthquake EQ1 and strong earthquake EQ2, were numerically investigated. The seismic behaviors of ground composed of cohesionless sandy soil and cohesive clayey soil were uniformly described by the cyclic mobility (CM) model, which is capable of describing accurately the mechanical property of the soil due to monotonic and cyclic loadings by accounting for stress-induced anisotropy, over-consolidation, and soil structure. It is known from the numerical investigation that the embankment would experience destructive deformation, and that the collapse mode was closely related to the properties of input seismic motion because high intensities and long durations of an earthquake motion could lead to significant plastic deformation and prolonged soil liquefaction. Under the strong seismic loading of EQ2, a circular collapse surface, combined with huge settlement and lateral spread, occurred inside the liquefication zone and extended towards the embankment crest. In contrast, in moderate earthquake EQ1, upheaval was observed at each toe of the embankment, and instability occurred only in the liquefied ground. An anti-liquefaction remediation via grouting was determined to significantly reduce liquefaction-induced deformation (settlement, lateral spreading, and local uplift) and restrain the deep-seated circular sliding failure, even though the top sandy soil liquefied in both earthquakes. When the structure was subjected to EQ2 motion, local failure occurred on the embankment slope reinforced with grouting, and thus, an additional appropriate countermeasure should be implemented to further strengthen the slope. For both input motions, the surface deformation of the considered embankment decreased gradually as the thickness of reinforcement was increased, although the reinforcement effect was no longer significant once the thickness exceeded 6 m.

关键词： dynamic response     earth embankment     damage pattern     liquefaction     ground improvement    

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Apigenin alleviates neomycin-induced oxidative damage via the Nrf2 signaling pathway in cochlear hair

《医学前沿（英文）》 2022年 第16卷 第4期   页码 637-650 doi: 10.1007/s11684-021-0864-3

摘要： Oxidative stress plays an important role in the pathogenesis of aminoglycoside-induced hearing loss and represents a promising target for treatment. We tested the potential effect of apigenin, a natural flavonoid with anticancer, anti-inflammatory, and antioxidant activities, on neomycin-induced ototoxicity in cochlear hair cells in vitro. Results showed that apigenin significantly ameliorated the loss of hair cells and the accumulation of reactive oxygen species upon neomycin injury. Further evidence suggested that the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway was activated by apigenin treatment. Disruption of the Nrf2 axis abolished the effects of apigenin on the alleviation of oxidative stress and subsequent apoptosis of hair cells. This study provided evidence of the protective effect of apigenin on cochlear hair cells and its underlying mechanism.

关键词： apigenin     aminoglycosides     ototoxicity     oxidative stress     Nrf2 signaling pathway    

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Relationship between reactive oxygen species and sodium-selenite-induced DNA damage in HepG2 cells

ZOU Yunfeng, NIU Piye, GONG Zhiyong, YANG Jin, YUAN Jing, WU Tangchun, CHEN Xuemin

《医学前沿（英文）》 2007年 第1卷 第3期   页码 327-332 doi: 10.1007/s11684-007-0063-x

摘要： Selenium compounds, as an effective chemopreventive agent, can induce apoptosis in tumor cells. Reactive oxygen species (ROS) are important mediators in apoptosis induced by various stimuli, which include chemopreventive agents. In this study, we investigated the relationship between ROS and the levels of DNA damage induced by selenite in HepG2 cells. After HepG2 cells were treated with selenite, there was a dose-dependent decrease in cell viability. The levels of ROS induced by selenite were measured by 2′, 7′-dichlorofluorescein diacetate (DCFH-DA) fluorescence, which shows a dose- and time-dependent increase in HepG2 cells. The levels of DNA damage in HepG2 increased in all cells treated with an increasing dose of selenite at 0, 2.5, 5, 10, and 20 μmol/L. N-acetylcysteine (NAC), a known antioxidant, increased cell viability and decreased ROS generation. Moreover, NAC effectively blocked DNA damage induced by selenite. These results revealed that ROS might play an important role in selenite-induced DNA damage that can be reduced by NAC treatment.

关键词： NAC     N-acetylcysteine     DNA     fluorescence     relationship    

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A step forward towards a comprehensive framework for assessing liquefaction land damage vulnerability

Mahmood AHMAD, Xiao-Wei TANG, Jiang-Nan QIU, Feezan AHMAD, Wen-Jing GU

《结构与土木工程前沿（英文）》 2020年 第14卷 第6期   页码 1476-1491 doi: 10.1007/s11709-020-0670-z

摘要： The unprecedented liquefaction-related land damage during earthquakes has highlighted the need to develop a model that better interprets the liquefaction land damage vulnerability (LLDV) when determining whether liquefaction is likely to cause damage at the ground’s surface. This paper presents the development of a novel comprehensive framework based on select case history records of cone penetration tests using a Bayesian belief network (BBN) methodology to assess seismic soil liquefaction and liquefaction land damage potentials in one model. The BBN-based LLDV model is developed by integrating multi-related factors of seismic soil liquefaction and its induced hazards using a machine learning (ML) algorithm-K2 and domain knowledge (DK) data fusion methodology. Compared with the C4.5 decision tree-J48 model, naive Bayesian (NB) classifier, and BBN-K2 ML prediction methods in terms of overall accuracy and the Cohen’s kappa coefficient, the proposed BBN K2 and DK model has a better performance and provides a substitutive novel LLDV framework for characterizing the vulnerability of land to liquefaction-induced damage. The proposed model not only predicts quantitatively the seismic soil liquefaction potential and its ground damage potential probability but can also identify the main reasons and fault-finding state combinations, and the results are likely to assist in decisions on seismic risk mitigation measures for sustainable development. The proposed model is simple to perform in practice and provides a step toward a more sophisticated liquefaction risk assessment modeling. This study also interprets the BBN model sensitivity analysis and most probable explanation of seismic soil liquefied sites based on an engineering point of view.

关键词： Bayesian belief network     liquefaction-induced damage potential     cone penetration test     soil liquefaction     structural learning and domain knowledge    

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Confined masonry as practical seismic construction alternative–the experience from the 2014 Cephalonia

Fillitsa KARANTONI, Stavroula PANTAZOPOULOU, Athanasios GANAS

《结构与土木工程前沿（英文）》 2018年 第12卷 第3期   页码 270-290 doi: 10.1007/s11709-017-0390-1

摘要：

During August 1953 three strong earthquakes of magnitude ranging from 6.3 to 7.2 shook the Ionian Island of Cephalonia (Kefalonia), Greece, and destroyed almost the entire building stock of the Island which consisted primarily of traditional unreinforced masonry (URM) houses. The authorities went on to restructuring of the building stock, using a structural system that is most like what is known today as confined masonry. They designed about 14 types of one- to two-storey buildings providing the engineers with detailed construction plans. These buildings are known as “Arogi” buildings (Arogi in Greek meaning Aid). On the 24th of January and 3rd of February 2014, two earthquakes of magnitude 6.1 and 6.0 struck the island, causing significant soil damages, developing excessively high ground accelerations. Surprisingly, no damage was reported in the “Arogi” buildings. The seismic behavior of the buildings is examined by FEM linear analysis and it is compared to that of URM structures. Computed results illustrate that the displacements of identical URM buildings would be about twice the magnitudes observed in the corresponding “Arogi” ones, with the implication that the earthquake sequence of 2014 would have caused critical damage should the type of structure be of the URM type. Furthermore, it is illustrated that this low cost alternative method of construction is a very effective means of producing earthquake resilient structures, whereas further reduction of seismic displacement may be achieved in the order of 50% with commensurate effects on damage potential, when reinforced slabs are used to replace the timber roofs.

关键词： Cephalonia     confined masonry     comparative FEM analysis     unreinforced masonry     seismic damage    

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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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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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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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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    

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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    

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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    

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标题 作者 时间 类型 操作

Influence of construction-induced damage on the degradation of freeze–thawed lightweight cellular concrete

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

Liquefaction-induced damage evaluation of earth embankment and corresponding countermeasure

Linlin GU; Wei ZHENG; Wenxuan ZHU; Zhen WANG; Xianzhang LING; Feng ZHANG

期刊论文

Apigenin alleviates neomycin-induced oxidative damage via the Nrf2 signaling pathway in cochlear hair

期刊论文

Relationship between reactive oxygen species and sodium-selenite-induced DNA damage in HepG2 cells

ZOU Yunfeng, NIU Piye, GONG Zhiyong, YANG Jin, YUAN Jing, WU Tangchun, CHEN Xuemin

期刊论文

A step forward towards a comprehensive framework for assessing liquefaction land damage vulnerability

Mahmood AHMAD, Xiao-Wei TANG, Jiang-Nan QIU, Feezan AHMAD, Wen-Jing GU

期刊论文

Confined masonry as practical seismic construction alternative–the experience from the 2014 Cephalonia

Fillitsa KARANTONI, Stavroula PANTAZOPOULOU, Athanasios GANAS

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

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