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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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A combination of damage locating vector method (DLV) and differential evolution algorithm (DE) for structuraldamage assessment

T. NGUYEN-THOI, A. TRAN-VIET, N. NGUYEN-MINH, T. VO-DUY, V. HO-HUU

《结构与土木工程前沿（英文）》 2018年第12卷第1期页码 92-108 doi: 10.1007/s11709-016-0379-1

摘要： In this study, a two-stage method is presented for identifying multiple damage scenarios. In the first stage, the damage locating vector (DLV) method using normalized cumulative energy ( ) is employed for damage localization in structures. In the second stage, the differential evolution algorithm (DE) is used for damage severity of the structures. In addition, in the second stage, a modification of an available objective function is made for handing the issue of symmetric structures. To verify the effectiveness of the present technique, numerical examples of a 72-bar space truss and a one-span steel portal frame are considered. In addition, the effect of noise on the performance of the identification results is also investigated. The numerical results show that the proposed combination gives good assessment of damage location and extent for multiple structural damage cases.

关键词： damage assessment damage locating vector method (DLV) differential evolution (DE) multiple damage location assurance criterion (MDLAC) mode shape error function

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一种损伤演化方程的建立和几种层裂准则的推导

曹结东,李永池

《中国工程科学》 2006年第8卷第1期页码 40-45

摘要：

通过唯象分析和细观统计相结合的方法建立了一种韧性材料的损伤演化方程，从物理上对方程中的参数进行了合理的解释，并以此为依据推导了材料的便于工程应用的几种层裂准则，根据准则总结了一些有意义的层裂规律；通过层裂实验和数值模拟相结合的方法来确定材料参数，计算结果与实验结果较好的一致性验证了所建的损伤演化方程和推导的层裂准则是合理的，决定材料参数的方法是有效的。

关键词：损伤演化方程层裂准则数值模拟

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An enhanced damage plasticity model for predicting the cyclic behavior of plain concrete under multiaxial

Mohammad Reza AZADI KAKAVAND, Ertugrul TACIROGLU

《结构与土木工程前沿（英文）》 2020年第14卷第6期页码 1531-1544 doi: 10.1007/s11709-020-0675-7

摘要： Some of the current concrete damage plasticity models in the literature employ a single damage variable for both the tension and compression regimes, while a few more advanced models employ two damage variables. Models with a single variable have an inherent difficulty in accounting for the damage accrued due to tensile and compressive actions in appropriately different manners, and their mutual dependencies. In the current models that adopt two damage variables, the independence of these damage variables during cyclic loading results in the failure to capture the effects of tensile damage on the compressive behavior of concrete and vice-versa. This study presents a cyclic model established by extending an existing monotonic constitutive model. The model describes the cyclic behavior of concrete under multiaxial loading conditions and considers the influence of tensile/compressive damage on the compressive/tensile response. The proposed model, dubbed the enhanced concrete damage plasticity model (ECDPM), is an extension of an existing model that combines the theories of classical plasticity and continuum damage mechanics. Unlike most prior studies on models in the same category, the performance of the proposed ECDPM is evaluated using experimental data on concrete specimens at the material level obtained under cyclic multiaxial loading conditions including uniaxial tension and confined compression. The performance of the model is observed to be satisfactory. Furthermore, the superiority of ECDPM over three previously proposed constitutive models is demonstrated through comparisons with the results of a uniaxial tension-compression test and a virtual test.

关键词： damage plasticity model plain concrete cyclic loading multiaxial loading conditions

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岩石冲击损伤演化规律数值流形方法模拟

刘红岩,吕淑然,秦四清

《中国工程科学》 2007年第9卷第3期页码 92-96

摘要：

采用应力波衰减损伤模型对仅适用于模拟基于线性本构关系和恒定载荷作用下物体变形规律的数值流形程序进行了扩展；利用扩展后的程序对岩石长杆在冲击载荷作用下的损伤演化规律进行了模拟，得出了不同位置点处的损伤演化曲线和材料总体的损伤演化曲线。模拟结果表明，损伤的增加主要集中在冲击载荷作用的初始阶段，随着时间的推移，应力波强度衰减，损伤将不再明显增加。

关键词：岩石数值流形方法冲击损伤演化规律

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Cyclic behavior of prefabricated reinforced concrete frame with infill slit shear walls

Kui XIAO,Qilin ZHANG,Bin JIA

《结构与土木工程前沿（英文）》 2016年第10卷第1期页码 63-71 doi: 10.1007/s11709-015-0294-x

摘要： A composite structural system consisting of prefabricated reinforced concrete frame with infill slit shear walls (PRCFW), with good ductility, is a new type of earthquake resistant structure. Pseudo-static tests were performed to evaluate the seismic behavior of the PRCFW system. Two one-bay, two-story PRCFW specimens were both built at one-half scale. Additional computational research is also conducted to enhance the nonlinear analytical capabilities for this system. Combined with the concrete damaged plastic (CDP) model provided by finite element program ABAQUS and the constitutive model of concrete proposed by Chinese code, the damage process of the PRCFW structure under cyclic load is simulated. The simulated results show a good agreement with the test data, the dynamic behavior of the PRCFW system can be simulated sufficiently accurate and efficient to provide useful design information. The experimental and numerical study show that this system has the potential to offer good ductility and energy absorption capacity to dissipate input energy, and stiffness adequate for controlling drift for buildings located in earthquake-prone regions.

关键词： slit shear wall constitutive model cyclic seismic damage

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Effects of herding behavior of tradable green certificate market players on market efficiency: Insights

《能源前沿（英文）》 2023年第17卷第2期页码 266-285 doi: 10.1007/s11708-021-0752-1

摘要： Tradable green certificate (TGC) scheme promotes the development of renewable energy industry which currently has a dual effect on economy and environment. TGC market efficiency is reflected in stimulating renewable energy investment, but may be reduced by the herding behavior of market players. This paper proposes and simulates an artificial TGC market model which contains heterogeneous agents, communication structure, and regulatory rules to explore the characteristics of herding behavior and its effects on market efficiency. The results show that the evolution of herding behavior reduces information asymmetry and improves market efficiency, especially when the borrowing is allowed. In addition, the fundamental strategy is diffused by herding evolution, but TGC market efficiency may be remarkably reduced by herding with borrowing mechanism. Moreover, the herding behavior may evolve to an equilibrium where the revenue of market players is comparable, thus the fairness in TGC market is improved.

关键词： tradable green certificate herding behavior evolution heterogeneous agent model complex network

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Cracking evolution behaviors of lightweight materials based on

Y. Luo, S. C. Wu, Y. N. Hu, Y. N. Fu

《机械工程前沿（英文）》 2018年第13卷第4期页码 461-481 doi: 10.1007/s11465-018-0481-2

摘要：

Damage accumulation and failure behaviors are crucial concerns during the design and service of a critical component, leading researchers and engineers to thoroughly identifying the crack evolution. Third-generation synchrotron radiation X-ray computed microtomography can be used to detect the inner damage evolution of a large-density material or component. This paper provides a brief review of studying the crack initiation and propagation inside lightweight materials with advanced synchrotron three-dimensional (3D) X-ray imaging, such as aluminum materials. Various damage modes under both static and dynamic loading are elucidated for pure aluminum, aluminum alloy matrix, aluminum alloy metal matrix composite, and aluminum alloy welded joint. For aluminum alloy matrix, metallurgical defects (porosity, void, inclusion, precipitate, etc.) or artificial defects (notch, scratch, pit, etc.) strongly affect the crack initiation and propagation. For aluminum alloy metal matrix composites, the fracture occurs either from the particle debonding or voids at the particle/matrix interface, and the void evolution is closely related with fatigued cycles. For the hybrid laser welded aluminum alloy, fatigue cracks usually initiate from gas pores located at the surface or sub-surface and gradually propagate to a quarter ellipse or a typical semi-ellipse profile.

关键词： fatigue crack initiation and growth fatigue damage mechanism damage tolerance defect characterization laser welded aluminum alloys

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Nonlinear dynamic behavior of rotating blade with breathing crack

Laihao YANG, Zhu MAO, Shuming WU, Xuefeng CHEN, Ruqiang YAN

《机械工程前沿（英文）》 2021年第16卷第1期页码 196-220 doi: 10.1007/s11465-020-0609-z

摘要： This study aims at investigating the nonlinear dynamic behavior of rotating blade with transverse crack. A novel nonlinear rotating cracked blade model (NRCBM), which contains the spinning softening, centrifugal stiffening, Coriolis force, and crack closing effects, is developed based on continuous beam theory and strain energy release rate method. The rotating blade is considered as a cantilever beam fixed on the rigid hub with high rotating speed, and the crack is deemed to be open and close continuously in a trigonometric function way with the blade vibration. It is verified by the comparison with a finite element-based contact crack model and bilinear model that the proposed NRCBM can well capture the dynamic characteristics of the rotating blade with breathing crack. The dynamic behavior of rotating cracked blade is then investigated with NRCBM, and the nonlinear damage indicator (NDI) is introduced to characterize the nonlinearity caused by blade crack. The results show that NDI is a distinguishable indicator for the severity level estimation of the crack in rotating blade. It is found that severe crack (i.e., a closer crack position to blade root as well as larger crack depth) is expected to heavily reduce the stiffness of rotating blade and apparently result in a lower resonant frequency. Meanwhile, the super-harmonic resonances are verified to be distinguishable indicators for diagnosing the crack existence, and the third-order super-harmonic resonances can serve as an indicator for the presence of severe crack since it only distinctly appears when the crack is severe.

关键词： rotating blade breathing crack nonlinear vibration nonlinear damage indicator

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Ballistic behavior of plain and reinforced concrete slabs under high velocity impact

Chahmi OUCIF, Luthfi Muhammad MAULUDIN, Farid Abed

《结构与土木工程前沿（英文）》 2020年第14卷第2期页码 299-310 doi: 10.1007/s11709-019-0588-5

摘要： This work presents a numerical simulation of ballistic penetration and high velocity impact behavior of plain and reinforced concrete slabs. In this paper, we focus on the comparison of the performance of the plain and reinforced concrete slabs of unconfined compressive strength 41 MPa under ballistic impact. The concrete slab has dimensions of 675 mm × 675 mm × 200 mm, and is meshed with 8-node hexahedron solid elements in the impact and outer zones. The ogive-nosed projectile is considered as rigid element that has a mass of 0.386 kg and a length of 152 mm. The applied velocities vary between 540 and 731 m/s. 6 mm of steel reinforcement bars were used in the reinforced concrete slabs. The constitutive material modeling of the concrete and steel reinforcement bars was performed using the Johnson-Holmquist-2 damage and the Johnson-Cook plasticity material models, respectively. The analysis was conducted using the commercial finite element package Abaqus/Explicit. Damage diameters and residual velocities obtained by the numerical model were compared with the experimental results and effect of steel reinforcement and projectile diameter were studies. The validation showed good agreement between the numerical and experimental results. The added steel reinforcements to the concrete samples were found efficient in terms of ballistic resistance comparing to the plain concrete sample.

关键词： Johnson-Holmquist-2 Johnson-Cook reinforced concrete damage impact loads

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恶意代码行为描述与分析综述 Review

Bo YU, Ying FANG, Qiang YANG, Yong TANG, Liu LIU

《信息与电子工程前沿（英文）》 2018年第19卷第5期页码 583-603 doi: 10.1631/FITEE.1601745

摘要：基于行为的分析是恶意代码自动分析和检测过程中的一项重要技术，近年来得到学术界和工业界极大关注。恶意代码行为分析技术，能够避免传统静态分析技术遇到的恶意代码混淆的障碍，也能够通过行为描述规范表达恶意代码样本多样化的行为类型。目前，虽有一些关注恶意代码行为分析的工作，但基于行为的恶意代码分析技术仍未成熟，目前尚未发现介绍当前研究进展和发展挑战的综述。本文从3个方面对恶意代码的行为描述和分析进行综述：恶意代码行为描述，恶意代码行为分析模型，可视化。首先，全面梳理了现有行为分析技术的分析目标、原则、特点和分类，包括现有行为数据类型和描述方法；其次，从多方面分析恶意代码分析的不足和挑战；最后，探讨了潜在研究热点。

关键词：恶意代码行为；静态分析；动态分析；行为数据表示；行为分析；机器学习；基于语义的分析；行为可视化；恶意代码演化

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Experimental and numerical investigations of the compressive behavior of carbon fiber-reinforced polymer-strengthened

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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Nonlinear numerical simulation of punching shear behavior of reinforced concrete flat slabs with shear-heads

Dan V. BOMPA, Ahmed Y. ELGHAZOULI

《结构与土木工程前沿（英文）》 2020年第14卷第2期页码 331-356 doi: 10.1007/s11709-019-0596-5

摘要： This paper examines the structural response of reinforced concrete flat slabs, provided with fully-embedded shear-heads, through detailed three-dimensional nonlinear numerical simulations and parametric assessments using concrete damage plasticity models. Validations of the adopted nonlinear finite element procedures are carried out against experimental results from three test series. After gaining confidence in the ability of the numerical models to predict closely the full inelastic response and failure modes, numerical investigations are carried out in order to examine the influence of key material and geometric parameters. The results of these numerical assessments enable the identification of three modes of failure as a function of the interaction between the shear-head and surrounding concrete. Based on the findings, coupled with results from previous studies, analytical models are proposed for predicting the rotational response as well as the ultimate strength of such slab systems. Practical recommendations are also provided for the design of shear-heads in RC slabs, including the embedment length and section size. The analytical expressions proposed in this paper, based on a wide-ranging parametric assessment, are shown to offer a more reliable design approach in comparison with existing methods for all types of shear-heads, and are suitable for direct practical application.

关键词： non-linear numerical modelling concrete damage plasticity RC flat slabs shear-heads punching shear

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小型制冷系统的稳态模拟

王婷,陈海耿,赵巍,崔苗

《中国工程科学》 2007年第9卷第3期页码 97-102

摘要：

所建立的小型制冷系统模型包括压缩机、冷凝器、膨胀阀和蒸发器四个部件模型以及使系统封闭的充灌量模型，实现了所有相关物性参数计算的程序化以便于模型的数值求解。在蒸发器模型中提出了析湿系数的新算法，加速了模型的计算。用所建立的模型模拟工作参数的变化对系统性能的影响，其结果与实际规律相符合，证明了该模型的正确性。根据模型得出的定量结果可分析各性能参数变化的相互影响，并对性能参数的敏感性进行分析，为系统优化和控制提供理论依据。此外，换热器模型还可独立用于各种换热器性能的分析与优化。

关键词：制冷系统析湿系数稳态模型

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Influence of damages on static behavior of single-layer cable net supported glass curtain wall: full-scale

Gang SHI, Yongjiu SHI, Yuanqing WANG, Yongzhi ZUO, Xiaohao SHI, Zaoyang GUO,

《结构与土木工程前沿（英文）》 2010年第4卷第3期页码 383-395 doi: 10.1007/s11709-010-0074-6

摘要： The single-layer cable net supported glass curtain wall has been applied in many building structures all over the world. In service, it will inevitably be subject to various damages. To study the influence of such damages on the static behavior of the single-layer cable net supported glass curtain wall, a full-scale model with the outside outline size of 4.85 m × 4.85 m and 4 × 4 grids is designed and tested. Two kinds of damages that are the cable prestress loss and cable anchorage end failure are led into the structure model during the test, and their influence has been investigated. The stiffness contribution of glass panels to the single-layer cable net supported glass curtain wall structure with or without damages and its change have been tested and analyzed. The results show that the maximum change rate of nodal deflection is 13.78% for the damage of cable prestress loss, while the change rate of nodal deflection is between 7% and 22% for the damage of cable anchorage end failure. The influence degree of the damages depends on the ratio of the structure initial stress stiffness change caused by damages to the total stiffness of the structure. The stiffness contribution of glass panels increases with the load increase. Under the same loading condition, the stiffness contribution of glass panels to the damaged structure is greater than that to the intact structure. The stiffness contribution of glass panels reduces the effect of the damages on the structural displacement and the cable tension force, but the glass panel could break if its stiffness contribution is too large.

关键词： single-layer plane cable net supported glass curtain wall damage cable prestress loss cable anchorage end failure stiffness contribution of glass panels