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混凝土 16

三峡工程 7

三峡升船机 4

应力状态 3

混凝土面板堆石坝 3

DX桩 2

三点弯曲梁 2

优化 2

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升船机 2

应力 2

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强度理论 2

有限元法 2

残余应力 2

混凝土坝 2

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Damage-constitutive model for seawater coral concrete using different stirrup confinements subjected

《结构与土木工程前沿（英文）》 2023年 第17卷 第3期   页码 429-447 doi: 10.1007/s11709-022-0913-2

摘要： Recently, the application of detrital coral as an alternative to natural aggregates in marine structures has attracted increased attention. In this study, research on the compressive performance of coral aggregate concrete (CAC) confined using steel stirrups with anti-rust treatment was experimentally conducted. A total of 45 specimens were cast, including 9 specimens without stirrups and under different strength grades (C20, C30, and C40) and 36 specimens under different strength grades (C20, C30, and C40). Moreover, three stirrup levels (rectangular, diamond-shaped compound, and spiral stirrups) and different stirrup spacings (40, 50, 60, and 70 mm) were used. Subsequently, the stress−strain curves of specimens subjected to axial loading were measured. The effects of the stirrup spacing and stirrup configurations on the stress and strain were investigated, respectively, and the lateral effective stress of the different stirrups was calculated based on the cohesive-elastic ring model and modified elastic beam theory. Moreover, a damage-constitutive model of CAC considering the lateral stress was set up based on damage mechanics theory. The results indicated an increase in the stress and strain with a decrease in the stirrup spacing, and the adopted stirrup ratio had a better strengthening effect than the different concrete grades, and the variation in the deformation was restricted by the performance of coral coarse aggregate (CA). However, an increment in the lateral strain was observed with an increase in the axial strain. The lateral stress model showed a good agreement with the experimental data, and the proposed damage-constitutive model had a good correlation with the measured stress−strain curves.

关键词： coral aggregate concrete     stress−strain curves     lateral effective stress     peak stress     axial−lateral curves     damage-constitutive model.    

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Risk-based probabilistic thermal-stress analysis of concrete arch dams

Narjes SOLTANI, Mohammad ALEMBAGHERI, Mohammad Houshmand KHANEGHAHI

《结构与土木工程前沿（英文）》 2019年 第13卷 第5期   页码 1007-1019 doi: 10.1007/s11709-019-0521-y

摘要： The probabilistic risk of arch dam failure under thermal loading is studied. The incorporated uncertainties, which are defined as random variables, are associated with the most affecting structural (material) properties of concrete and thermal loading conditions. Karaj arch dam is selected as case study. The dam is numerically modeled along with its foundation in three-dimensional space; the temperature and thermal stress distribution is investigated during the operating phase. The deterministic thermal finite element analysis of the dam is combined with the structural reliability methods in order to obtain thermal response predictions, and estimate the probability of failure in the risk analysis context. The tensile overstressing failure mode is considered for the reliability analysis. The thermal loading includes ambient air and reservoir temperature variations. The effect of solar radiation is considered by an increase in the ambient temperatures. Three reliability methods are employed: the first-order second-moment method, the first-order reliability method, and the Monte-Carlo simulation with Latin Hypercube sampling. The estimated failure probabilities are discussed and the sensitivity of random variables is investigated. Although most of the studies in this line of research are used only for academic purposes, the results of this investigation can be used for both academic and engineering purposes.

关键词： arch dams     probabilistic analysis     thermal stress     sensitivity     reliability    

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Stress-strain relationship of concrete in freeze-thaw environment

ZOU Chaoying, ZHAO Juan, LIANG Feng

《结构与土木工程前沿（英文）》 2008年 第2卷 第2期   页码 184-188 doi: 10.1007/s11709-008-0029-3

摘要： Adopting the ASTM C666 quick freeze-thaw method, freeze-thaw tests with the number of freeze-thaw cycles being 0, 100, 150, 200, 250, and 300, were carried out on eighteen concrete prism specimens, the frost-resistant level of which, reaches D300 grade. The internal micro-structures of these specimens were observed by means of scanning electron microscopy (SEM) in order to detect damages caused by the freeze-thaw action. Afterwards these frozen-thawed specimens were tested on monotonic axial load; stress-strain testing curves after the freeze-thaw action were obtained. The testing results show that with the increasing time of freeze-thaw cycles, both the internal micro-structures and the basic mechanical parameters, including the ultimate bearing capacity, the Poisson ratio and the modulus of elasticity, degenerate in various degrees. Finally, stress-strain theoretical curvilinear equations and correlated parameters relating to the loss of relative dynamic modulus of elasticity were proposed. These results provide great reference for further research on the behavior and the calculation model of concrete structures in a freeze-thaw environment.

关键词： stress-strain theoretical     freeze-thaw     capacity     reference     eighteen concrete    

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论混凝土坝的几个重要问题

朱伯芳

《中国工程科学》 2006年 第8卷 第7期   页码 21-29

摘要：

目前我国在建混凝土坝的高度、数量、规模均居世界第一位，文章就混凝土坝技术的几个重要问题进行讨论：（1）结束“无坝不裂”历史的关键技术；（2）应用氧化镁混凝土筑坝的两种指导思想和两种实践结果；（3）混凝土强度等级应用于混凝土坝欠妥，坝工混凝土仍以采用混凝土标号为宜；（4）我国特高拱坝的抗压安全系数偏低，应适当提高。（5）拱坝有限元等效应力问题。

关键词： 混凝土坝     裂缝     混凝土标号     抗压安全系数     有限元等效应力    

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Influence of freeze–thaw damage gradient on stress–strain relationship of stressed concrete

《结构与土木工程前沿（英文）》   页码 1326-1340 doi: 10.1007/s11709-023-0014-x

摘要： Influence of freeze–thaw damage gradient on stress–strain relationship of stressed concrete

关键词： strain relationship concrete    

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Field test on temperature field and thermal stress for prestressed concrete box-girder bridge

Baoguo CHEN, Rui DING, Junjie ZHENG, Shibiao ZHANG

《结构与土木工程前沿（英文）》 2009年 第3卷 第2期   页码 158-164 doi: 10.1007/s11709-009-0002-9

摘要： A field test was conducted to investigate the distribution of temperature field and the variation of thermal stress for a prestressed concrete (PC) box-girder bridge. The change of hydration heat temperature consists of four periods: temperature rising period, constant temperature period, rapid temperature fall period and slow temperature fall period. The peak value of hydration heat temperature increases with the increasing casting temperature of concrete; the relation between them is approximately linear. According to field tests, the thermal stress incurred by hydration heat may induce temperature cracks on the PC box-girder. Furthermore, the nonlinear distribution of temperature gradient and the fluctuation of thermal stress induced by exposure to sunlight were also obtained based on continuous in-situ monitoring. Such results show that the prevailing Chinese Code (2004) is insufficient since it does not take into account the temperature gradient of the bottom slab. Finally, some preventive measures against temperature cracks were proposed based on related studies. The conclusions can provide valuable reference for the design and construction of PC box-girder bridges.

关键词： box-girder bridge     field test     hydration heat     temperature field     temperature gradient     thermal stress    

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Stress-strain relationship of recycled self-compacting concrete filled steel tubular column subjected

Feng YU, Cheng QIN, Shilong WANG, Junjie JIANG, Yuan FANG

《结构与土木工程前沿（英文）》 2020年 第14卷 第3期   页码 760-772 doi: 10.1007/s11709-020-0618-3

摘要： As a typical compression member, the concrete-filled steel tube has been widely used in civil engineering structures. However, little research on recycled self-compacting concrete filled circular steel tubular (RSCCFCST) columns subjected to eccentric load was reported. In this study, 21 specimens were designed and experimental studies on the stress-strain relationship of were carried out to study the mechanical behaviors. Recycled coarse aggregate replacement ratio, concrete strength grade, length to diameter ratio and eccentric distance of specimens were considered as the main experimental parameters to carry out eccentric compression tests. The corresponding stress-strain relationship curves were used to analyze the influence of concerned parameters on eccentric load-bearing capacity of RSCCFCST columns. The experimental results show that the strain of the eccentric compression stress-strain curves increase with the increase of recycled coarse aggregate replacement ratio and concrete strength grade. With increase of eccentric distance, the ductility of specimens increases while the bearing capacity decreases. Moreover, a phenomenological model of RSCCFCST columns is proposed, which exhibits versatile ability to capture the process during loading. The present study is expected to further understanding the behaviors and to provide guidance of RSCCFCST columns in design and engineering applications.

关键词： concrete filled circular steel tubular columns     recycled self-compacting concrete     eccentric compression     recycled coarse aggregate replacement ratio     stress-strain relationship    

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Confinement properties of circular concrete columns wrapped with prefabricated textile-reinforced fineconcrete shells

《结构与土木工程前沿（英文）》 doi: 10.1007/s11709-023-0955-0

摘要： This paper proposes an innovative column composed of a core column (including both reinforced concrete (RC) and plain concrete (PC) columns) and a prefabricated textile-reinforced fine concrete (TRC) shell. To study the confinement properties of TRC shells on this novel type of concrete column, 20 circular specimens, including 12 PC columns and 8 RC columns, were prepared for axial compressive tests. Four key parameters, including the column size, reinforcing ratio of the carbon textile, concrete strength, and stirrup spacing, were evaluated. The results indicated that the compressive properties of the columns were improved by increasing the reinforcing ratio of the textile layers. In the case of TRC-confined PC columns, the maximum improvement in the peak load was 56.3%, and for TRC-confined RC columns, the maximum improvement was 60.2%. Based on the test results, an analytical model that can be used to calculate the stress–strain curves of prefabricated TRC shell-confined concrete columns has been proposed. The calculated curves predicted by the proposed model agreed well with the test results.

关键词： textile-reinforced fine concrete     prefabricated shell     confined concrete column     confinement properties     stress–strain relationship    

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Layout optimization of steel reinforcement in concrete structure using a truss-continuum model

《结构与土木工程前沿（英文）》 2023年 第17卷 第5期   页码 669-685 doi: 10.1007/s11709-023-0963-0

摘要： Owing to advancement in advanced manufacturing technology, the reinforcement design of concrete structures has become an important topic in structural engineering. Based on bi-directional evolutionary structural optimization (BESO), a new approach is developed in this study to optimize the reinforcement layout in steel-reinforced concrete (SRC) structures. This approach combines a minimum compliance objective function with a hybrid truss-continuum model. Furthermore, a modified bi-directional evolutionary structural optimization (M-BESO) method is proposed to control the level of tensile stress in concrete. To fully utilize the tensile strength of steel and the compressive strength of concrete, the optimization sensitivity of steel in a concrete–steel composite is integrated with the average normal stress of a neighboring concrete. To demonstrate the effectiveness of the proposed procedures, reinforcement layout optimizations of a simply supported beam, a corbel, and a wall with a window are conducted. Clear steel trajectories of SRC structures can be obtained using both methods. The area of ​​critical tensile stress in concrete yielded by the M-BESO is more than 40% lower than that yielded by the uniform design and BESO. Hence, the M-BESO facilitates a fully digital workflow that can be extremely effective for improving the design of steel reinforcements in concrete structures.

关键词： bi-directional evolutionary structural optimization     steel-reinforced concrete     concrete stress     reinforcement method     hybrid model    

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Chloride diffusion in concrete with carbonated recycled coarse aggregates under biaxial compression

《结构与土木工程前沿（英文）》 2023年 第17卷 第4期   页码 637-648 doi: 10.1007/s11709-023-0902-0

摘要： Chloride attack on concrete structures is affected by the complex stress state inside concrete, and the effect of recycled aggregates renders this process more complex. Enhancing the chloride resistance of recycled concrete in a complex environment via carbonization facilitates the popularization and application of recycled concrete and alleviates the greenhouse effect. In this study, the chloride ion diffusion and deformation properties of recycled concrete after carbonization are investigated using a chloride salt load-coupling device. The results obtained demonstrate that the chloride ion diffusivity of recycled concrete first decreases and then increases as the compressive load increases, which is consistent with the behavior of concrete, in that it first undergoes compressive deformation, followed by crack propagation. Carbonation enhances the performance of the recycled aggregates and reduces their porosity, thereby reducing the chloride diffusion coefficient of the recycled concrete under different compressive load combinations. The variation in the chloride ion diffusivity of the carbonized recycled aggregate concrete with the load is consistent with a theoretical formula.

关键词： recycled concrete     carbonated recycled coarse aggregate     biaxial compression     chloride diffusion     stress level    

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Shear assessment of compression flanges of structural concrete T-beams

Bj?rn SCHüTTE,Viktor SIGRIST

《结构与土木工程前沿（英文）》 2014年 第8卷 第4期   页码 354-361 doi: 10.1007/s11709-014-0082-z

摘要： In T-beams the force transfer from the web into the flange has to be studied. The general design procedure is based on a strut-and-tie (or a stress field) model which comprises spreading compressive and transverse tensile forces. As is known, strut-and-tie models represent the force flow within a structural member at ultimate. This procedure is sufficient for design purposes and in general, leads to safe results. For the assessment of a structure it may be worthwhile to improve the accuracy. For this purpose both web and flange have to be looked at more in detail. An advanced method for the analysis of webs in shear is the Generalized Stress Field Approach [ ]. This approach can be utilized for treating flanges, where the classical assumptions have to be adapted; in particular by considering the strain dependence of the concrete compressive strength and thus, defining a representative strain value. In the present contribution background and details of these aspects are given, and the corresponding calculation procedure is described. Theoretical results are compared with experimental data and show a reasonably good agreement. However, as the number of sufficiently documented tests is very limited no concluding findings are attained.

关键词： concrete structures     structural assessment     stress field analysis     shear    

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A time−space porosity computational model for concrete under sulfate attack

《结构与土木工程前沿（英文）》 doi: 10.1007/s11709-023-0985-7

摘要： The deterioration of the microscopic pore structure of concrete under external sulfate attack (ESA) is a primary cause of degradation. Nevertheless, little effort has been invested in exploring the temporal and spatial development of the porosity of concrete under ESA. This study proposes a mechanical–chemical model to simulate the spatiotemporal distribution of the porosity. A relationship between the corrosion damage and amount of ettringite is proposed based on the theory of volume expansion. In addition, the expansion strain at the macro-scale is obtained using a stress analysis model of composite concentric sphere elements and the micromechanical mean-field approach. Finally, considering the influence of corrosion damage and cement hydration on the diffusion of sulfate ions, the expansion deformation and porosity space−time distribution are obtained using the finite difference method. The results demonstrate that the expansion strains calculated using the suggested model agree well with previously reported experimental results. Moreover, the tricalcium aluminate concentration, initial elastic modulus of cement paste, corrosion damage, and continuous hydration of cement significantly affect concrete under ESA. The proposed model can forecast and assess the porosity of concrete covers and provide a credible approach for determining the residual life of concrete structures under ESA.

关键词： expansion deformation     porosity     internal expansion stress     external sulfate attack     mechanical–chemical coupling model    

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Unified calculation method and its application in determining the uniaxial mechanical properties of concrete

Faxing DING, Xiaoyong YING, Linchao ZHOU, Zhiwu YU

《结构与土木工程前沿（英文）》 2011年 第5卷 第3期   页码 381-393 doi: 10.1007/s11709-011-0118-6

摘要： This paper presents a unified calculation method and its application in determining the uniaxial mechanical properties of concrete with concrete strengths ranging from 10 to 140 MPa. By analyzing a large collection of test results of the uniaxial mechanical properties of normal-strength, high-strength and super high-strength concrete in China and performing a regression analysis, unified calculation formulas for the mechanical indexes of concrete are proposed that can be applied to various grades of concrete for determining the size coefficient, uniaxial compressive strength, uniaxial tensile strength, elastic modulus, and strain at peak uniaxial compression and tension. Optimized mathematical equations for the nonlinear stress-strain relationship of concrete, including the ascending and descending branches under uniaxial stress, are also established. The elastic modulus is almost constant throughout the elastic stage for the ascending branches of the stress-strain relationship for concrete. The proposed stress-strain relationship of concrete was applied to the nonlinear finite element analysis of both a steel-concrete composite beam and a concrete-filled steel tubular stub column. The analytical results are in good agreement with the experiment results, indicating that the proposed stress-strain relationship of concrete is applicable. The achievements presented in this paper can be used as references for the design and nonlinear finite element analysis of concrete structures.

关键词： concrete     mechanical properties     stress-strain relationship     uniaxial stress     application    

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Behavior of concrete-filled double skin steel tubular columns with octagon section under axial compression

YANG Junjie, PENG Guojun, XU Hanyong

《结构与土木工程前沿（英文）》 2008年 第2卷 第3期   页码 205-210 doi: 10.1007/s11709-008-0035-5

摘要： Based on some conclusions of two kinds of concrete-filled double skin steel tube (CFDSST) members with circular or square sections, a new kind of CFDSST with octagonal section, where the outer tube has an octagonal section and the inner tube has a circular section, is proposed in this paper. Behaviors of the CFDSST members with octagon section subjected to axial compression are investigated, and some curves of load-strain of steel tubes and confined concrete and the bearing capacity of members are obtained. It is indicated that the bearing capacity of the columns with octagonal section is larger than that with square section and is smaller than that with circular section, and the bearing capacity of members is related to the ratio of the straight side to the bevelled one. Based on the proper stress-strain relationship, a couple of numerical analyses are made using the finite element software named ANSYS. Finally, a simplified formula is proposed in the paper, and the numerical results agree well with the experimental results and the mathematical solutions. The results are valuable for engineers.

关键词： mathematical     numerical     compression     stress-strain relationship     straight    

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混凝土裂缝端部粘聚力的计算

徐世烺,王利民

《中国工程科学》 2002年 第4卷 第5期   页码 53-58

摘要：

混凝土裂缝端部断裂过程区的粘聚力分布是导致混凝土断裂呈现非线性特性的重要原因。基于混凝土的断裂特性和虚拟裂缝端部存在粘聚力的分析模型，并通过分布函数的特性分析，提出了粘聚力分布函数的两种简化表达式：一为单参数待定式，另一为双参数待定式。由变形体叠加原理，推导出计算单参数待定函数公式和计算双参数待定函数代数方程组。进而通过裂缝张开位移实测数据即可求得粘聚力分布，并且给出了适当的算例分析和讨论。

关键词： 混凝土     裂缝张开位移     虚拟裂缝粘聚力     代数方程    

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标题 作者 时间 类型 操作

Damage-constitutive model for seawater coral concrete using different stirrup confinements subjected

期刊论文

Risk-based probabilistic thermal-stress analysis of concrete arch dams

Narjes SOLTANI, Mohammad ALEMBAGHERI, Mohammad Houshmand KHANEGHAHI

期刊论文

Stress-strain relationship of concrete in freeze-thaw environment

ZOU Chaoying, ZHAO Juan, LIANG Feng

期刊论文

论混凝土坝的几个重要问题

朱伯芳

期刊论文

Influence of freeze–thaw damage gradient on stress–strain relationship of stressed concrete

期刊论文

Field test on temperature field and thermal stress for prestressed concrete box-girder bridge

Baoguo CHEN, Rui DING, Junjie ZHENG, Shibiao ZHANG

期刊论文

Stress-strain relationship of recycled self-compacting concrete filled steel tubular column subjected

Feng YU, Cheng QIN, Shilong WANG, Junjie JIANG, Yuan FANG

期刊论文

Confinement properties of circular concrete columns wrapped with prefabricated textile-reinforced fineconcrete shells

期刊论文

Layout optimization of steel reinforcement in concrete structure using a truss-continuum model

期刊论文

Chloride diffusion in concrete with carbonated recycled coarse aggregates under biaxial compression

期刊论文

Shear assessment of compression flanges of structural concrete T-beams

Bj?rn SCHüTTE,Viktor SIGRIST

期刊论文

A time−space porosity computational model for concrete under sulfate attack

期刊论文

Unified calculation method and its application in determining the uniaxial mechanical properties of concrete

Faxing DING, Xiaoyong YING, Linchao ZHOU, Zhiwu YU

期刊论文

Behavior of concrete-filled double skin steel tubular columns with octagon section under axial compression

YANG Junjie, PENG Guojun, XU Hanyong

期刊论文

混凝土裂缝端部粘聚力的计算

徐世烺,王利民

期刊论文