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Experimental investigation on mechanical properties of binary and ternary blended pervious concrete

Rekha SINGH, Sanjay GOEL

《结构与土木工程前沿（英文）》 2020年 第14卷 第1期   页码 229-240 doi: 10.1007/s11709-019-0597-4

摘要： The purpose of the investigation was to study the effect of binary and ternary blends of cement on the mechanical properties of pervious concrete (PC) specimen through destructive (DT) and non-destructive testing (NDT). Various combinations of fly ash (FA), limestone powder (LP), metakaolin (MK), and silica fume (SF) as mineral admixtures have been investigated to partially replace the cement up to 30% by weight in PC. Standard cube specimens of size 150 mm × 150 mm × 150 mm of binary and ternary blends of mineral admixture of pervious concrete were prepared to conduct standard compressive strength test and split tensile test at 7 and 28 days of curing. The ultrasonic pulse velocity (UPV) test and Rebound Hammer test were used as a non-destructive testing tool to substantiate the robustness of PC and to determine the approximate mechanical properties where other destructive testing tools are not feasible in case of in-place pervious pavements. Overall the pervious concrete made with LP based ternary blends (PLM and PLS) were found to perform better than FA based ternary blends (PFM and PFS) and control mix (PC) in destructive and non-destructive testing.

关键词： mineral admixture     ternary     compressive strength     split tensile strength     pervious concrete     ultrasonic pulse velocity    

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考虑垫片形状和尺寸效应的珊瑚混凝土劈裂抗拉性能的三维细观研究 Article

吴彰钰, 张锦华, 余红发, 方秦, 麻海燕, 陈力

《工程（英文）》 2022年 第17卷 第10期   页码 110-122 doi: 10.1016/j.eng.2021.02.024

摘要：

珊瑚混凝土（CAC）作为一种新型建筑材料，已经在岛礁工程结构建设领域引起了极大的关注。为了研究CAC的静态劈裂抗拉性能，本文提出了一种考虑骨料形状和空间分布随机性的三维（3D）随机混凝土细观模型，影响因素包括试件形状和支承垫片尺寸。我们建立了12 个不同的混凝土细观模型，按照试件形状可分为两种，即边长为150 mm的立方体和尺寸为ϕ150 mm×300 mm的圆柱体。其中，支承垫片宽度为6 mm、9 mm、12 mm、15 mm、18 mm和20 mm。本文系统分析和讨论了试件几何形状和垫片宽度对CAC劈裂抗拉性能的影响规律，研究内容包括混凝土开裂过程、最终破坏模式和劈裂抗拉强度（fst）。结果表明：本文所开发的细观模型具有很高的可靠性，并确定了适用于CAC劈裂抗拉性能模拟和预测的最优计算参数。CAC的fst值与试件形状和垫片宽度直接相关。其中，在垫片尺寸相同的情况下，立方体CAC试件的fst值要略高于圆柱体模型，表明可以采用断裂面积的差异来解释试件形状效应对CAC fst值的影响规律。此外，当垫片的相对宽度由0.04 增加到0.13 时，CAC的fst值会呈现逐渐增大的趋势。基于弹性力学理论，本文初步确定了不同垫片宽度条件下CAC fst的取值范围，这对于研究CAC的抗拉性能具有重要意义。

关键词： 珊瑚混凝土     三维细观模拟     劈拉试验     抗拉强度     试件形状     支承垫片    

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Behavior of steel fiber–reinforced high-strength concrete at medium strain rate

Chujie JIAO, Wei SUN, Shi HUAN, Guoping JIANG

《结构与土木工程前沿（英文）》 2009年 第3卷 第2期   页码 131-136 doi: 10.1007/s11709-009-0027-0

摘要： Impact compression experiments for the steel fiber–reinforced high-strength concrete (SFRHSC) at medium strain rate were conducted using the split Hopkinson press bar (SHPB) testing method. The volume fractions of steel fibers of SFRHSC were between 0 and 3%. The experimental results showed that, when the strain rate increased from threshold value to 90 s , the maximum stress of SFRHSC increased about 30%, the elastic modulus of SFRHSC increased about 50%, and the increase in the peak strain of SFRHSC was 2-3 times of that in the matrix specimen. The strength and toughness of the matrix were improved remarkably because of the superposition effect of the aggregate high-strength matrix and steel fiber high-strength matrix. As a result, under impact loading, cracks developed in the SFRHSC specimen, but the overall shape of the specimen remained virtually unchanged. However, under similar impact loading, the matrix specimens were almost broken into small pieces.

关键词： steel fiber–reinforced high-strength concrete (SFRHSC)     high strain rates     split Hopkinson press bar (SHPB)     strain rate hardening effects    

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Effect of size on biaxial flexural strength for cement-based materials by using a triangular plate method

Hakan T TURKER

《结构与土木工程前沿（英文）》 2022年 第16卷 第8期   页码 1017-1028 doi: 10.1007/s11709-022-0871-8

摘要： The effect of size on the biaxial flexural strength (BFS) of Portland cement mortar was investigated by using the recently proposed triangular plate method (TPM). An experimental program was conceived to study the size effect by keeping a constant water-cement ratio of 0.485, cement-sand ratio of 1:2.75, and using unreinforced triangular mortar plates of five different thicknesses and seven different side lengths. The BFS of the produced specimens was tested, and variations of BFS depending on specimen thickness and side length were determined. The results indicated that increases in triangular plate specimen side length and specimen thickness led to a decrease in the BFS of Portland cement mortar. The effect of specimen length increase on BFS was more significant than on the effect of the specimen thickness. The variations in specimens’ thickness indicated a deterministic Type I size effect, while the variations in specimens’ length showed an energetic-statistical Type I size effect.

关键词： testing     apparatus & methods     plain concrete     tensile properties     biaxial flexural strength     triangular plate method    

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Achieving High Strength and Tensile Ductility in Pure Nickel by Cryorolling with Subsequent Low-Temperature

Zhide Li,Hao Gu,Kaiguang Luo,Charlie Kong,Hailiang Yu,

《工程（英文）》 doi: 10.1016/j.eng.2023.01.019

摘要： ty. In this study, cryorolling under different strains followed by low-temperature short-time annealing was used to fabricate pure nickel sheets combining high strength with good ductility. The results show that, for different cryorolling strains, the uniform elongation was greatly increased without sacrificing the strength after annealing. A yield strength of 607 MPa and a uniform elongation of 11.7% were obtained after annealing at a small cryorolling strain (ε = 0.22), while annealing at a large cryorolling strain (ε = 1.6) resulted in a yield strength of 990 MPa and a uniform elongation of 6.4%. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and electron backscattered diffraction (EBSD) were used to characterize the microstructure of the specimens and showed that the high strength could be attributed to strain hardening during cryorolling, with an additional contribution from grain refinement and the formation of dislocation walls. The high ductility could be attributed to annealing twins and micro-shear bands during stretching, which improved the strain hardening capacity. The results show that the synergistic effect of strength and ductility can be regulated through low-temperature short-time annealing with different cryorolling strains, which provides a new reference for the design of future thermo-mechanical processes.

关键词： Cryorolling     Annealing     Nickel     Strain hardening     Ductility    

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Characterization of the tensile properties of friction stir welded aluminum alloy joints based on axial

Biranchi PANDA,A. GARG,Zhang JIAN,Akbar HEIDARZADEH,Liang GAO

《机械工程前沿（英文）》 2016年 第11卷 第3期   页码 289-298 doi: 10.1007/s11465-016-0393-y

摘要：

Friction stir welding (FSW) process has gained attention in recent years because of its advantages over the conventional fusion welding process. These advantages include the absence of heat formation in the affected zone and the absence of large distortion, porosity, oxidation, and cracking. Experimental investigations are necessary to understand the physical behavior that causes the high tensile strength of welded joints of different metals and alloys. Existing literature indicates that tensile properties exhibit strong dependence on the rotational speed, traverse speed, and axial force of the tool that was used. Therefore, this study introduces the experimental procedure for measuring tensile properties, namely, ultimate tensile strength (UTS) and tensile elongation of the welded AA 7020 Al alloy. Experimental findings suggest that a welded part with high UTS can be achieved at a lower heat input compared with the high heat input condition. A numerical approach based on genetic programming is employed to produce the functional relationships between tensile properties and the three inputs (rotational speed, traverse speed, and axial force) of the FSW process. The formulated models were validated based on the experimental data, using the statistical metrics. The effect of the three inputs on the tensile properties was investigated using 2D and 3D analyses. A high UTS was achieved, including a rotational speed of 1050 r/min and traverse speed of 95 mm/min. The results also indicate that 8 kN axial force should be set prior to the FSW process.

关键词： tensile properties     ultimate tensile strength     tensile elongation     friction stir welding     tool rotational speed     genetic programming     welding speed    

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Fresh and hardened properties of high-strength concrete incorporating byproduct fine crushed aggregate

Dammika P. K. WELLALA, Ashish Kumer SAHA, Prabir Kumar SARKER, Vinod RAJAYOGAN

《结构与土木工程前沿（英文）》 2021年 第15卷 第1期   页码 124-135 doi: 10.1007/s11709-020-0673-9

摘要： This paper presents the fresh and hardened properties of high-strength concrete comprising byproduct fine crushed aggregates (FCAs) sourced from the crushing of three different types of rocks, namely granophyre, basalt, and granite. The lowest void contents of the combined fine aggregates were observed when 40% to 60% of natural sand is replaced by the FCAs. By the replacement of 40% FCAs, the slump and bleeding of concrete with a water-to-cement ratio of 0.45 decreased by approximately 15% and 50%, respectively, owing to the relatively high fines content of the FCAs. The 28 d compressive strength of concrete was 50 MPa when 40% FCAs were used. The slight decrease in tensile strength from the FCAs is attributed to the flakiness of the particles. The correlations between the splitting tensile and compressive strengths of normal concrete provided in the AS 3600 and ACI 318 design standards are applicable for concrete using the FCAs as partial replacement of sand. The maximum 56 d drying shrinkage is 520 microstrains, which is significantly less than the recommended limit of 1000 microstrains by AS 3600 for concrete. Therefore, the use of these byproduct FCAs can be considered as a sustainable alternative option for the production of high-strength green concrete.

关键词： fine crushed aggregates     quarry dust     compressive strength     splitting tensile strength     drying shrinkage    

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Quantification of coarse aggregate shape in concrete

Xianglin GU,Yvonne TRAN,Li HONG

《结构与土木工程前沿（英文）》 2014年 第8卷 第3期   页码 308-321 doi: 10.1007/s11709-014-0266-6

摘要： The objective of this study is to choose indices for the characterization of aggregate form and angularity for large scale application. For this purpose, several parameters for aggregate form and angularity featured in previous research are presented. Then, based on these established parameters, 200 coarse quartzite aggregates are analyzed herein by using image processing technology. This paper also analyzes the statistical distributions of parameters for aggregate form and angularity as well as the correlation between form and angularity parameters. It was determined that the parameters for form or angularity of coarse aggregates could be fitted by either normal distribution or log-normal distribution at a 95% confidence level. Some of the form parameters were influenced by changes in angularity characteristics, while aspect ratio and angularity using outline slope, area ratio and radius angularity index, and aspect ratio and angularity index were independent of each other, respectively; and consequently, the independent parameters could be used to quantify the aggregate form and angularity for the purpose to study the influence of aggregate shape on the mechanical behavior of concrete. Furthermore, results from this study’s in-depth investigations showed that the aspect ratio and the angularity index can further understanding of the effects of coarse aggregates form and angularity on concrete mechanical properties, respectively. Finally, coarse aggregates with the same content, type and surfaces texture, but different aspect ratios and angularity indices were used to study the influence of coarse aggregate form and angularity on the behavior of concrete. It was revealed that the splitting tensile strength of concrete increased with increases in the aspect ratio or angularity index of coarse aggregates.

关键词： coarse aggregate     form     angularity     digital image analysis     statistical distribution     splitting tensile strength    

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Enhanced solution representations for vehicle routing problems with split deliveries

《工程管理前沿（英文）》   页码 483-498 doi: 10.1007/s42524-023-0259-z

摘要： In this study, we investigate a forest-based solution representation for split delivery vehicle routing problems (SDVRPs), which have several practical applications and are among the most difficult vehicle routing problems. The new solution representation fully reflects the nature of split delivery, and can help reduce the search space when used in heuristic algorithms. Based on the forest structure, we devise three neighborhood search operators. To highlight the effectiveness of this solution representation, we integrate these operators into a standard tabu search framework. We conduct extensive experiments on three main SDVRPs addressed in the literature: The basic SDVRP, the multidepot SDVRP, and the SDVRP with time windows. The experimental results show that the new forest-based solution representation is particularly effective in designing and implementing neighborhood operators, and that our new approach outperforms state-of-the-art algorithms on standard datasets.

关键词： vehicle routing     multidepot     time windows     tabu search     split delivery    

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performance with high compression ratio based on knock suppression using Miller cycle with boost pressure and split

Haiqiao WEI, Jie YU, Lei ZHOU

《能源前沿（英文）》 2019年 第13卷 第4期   页码 691-706 doi: 10.1007/s11708-019-0621-3

摘要： In theory, high compression ratio has the potential to improve the thermal efficiency and promote the power output of the SI engine. However, the application of high compression ratio is substantially limited by the knock in practical working process. The objective of this work is to comprehensively investigate the application of high compression ratio on a gasoline engine based on the Miller cycle with boost pressure and split injection. In this work, the specific optimum strategies for CR10 and CR12 were experimentally investigated respectively on a single cylinder DISI engine. It was found that a high level of Miller cycle with a higher boost pressure could be used in CR12 to achieve an effective compression ratio similar to CR10, which could eliminate the knock limits at a high compression ratio and high load. To verify the advantages of the high compression ratio, the fuel economy and power performance of CR10 and CR12 were compared at full and partial loads. The result revealed that, compared with CR10, a similar power performance and a reduced fuel consumption of CR12 at full load could be achieved by using the strong Miller cycle and split injection. At partial load, the conditions of CR12 had very superior fuel economy and power performance compared to those of CR10.

关键词： high compression ratio     knock     Miller cycle     split injection     engine performance    

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Acoustic emissions evaluation of the dynamic splitting tensile properties of steel fiber reinforced concrete

《结构与土木工程前沿（英文）》   页码 1341-1356 doi: 10.1007/s11709-023-0988-4

摘要： This study empirically investigated the influence of freeze–thaw cycling on the dynamic splitting tensile properties of steel fiber reinforced concrete (SFRC). Brazilian disc splitting tests were conducted using four loading rates (0.002, 0.02, 0.2, and 2 mm/s) on specimens with four steel fiber contents (0%, 0.6%, 1.2%, and 1.8%) subjected to 0 and 50 freeze–thaw cycles. The dynamic splitting tensile damage characteristics were evaluated using acoustic emission (AE) parameter analysis and Fourier transform spectral analysis. The results quantified using the freeze–thaw damage factor defined in this paper indicate that the degree of damage to SFRC caused by freeze–thaw cycling was aggravated with increasing loading rate but mitigated by increasing fiber content. The percentage of low-frequency AE signals produced by the SFRC specimens during loading decreased with increasing loading rate, whereas that of high-frequency AE signals increased. Freeze–thaw action had little effect on the crack types observed during the early and middle stages of the loading process; however, the primary crack type observed during the later stage of loading changed from shear to tensile after the SFRC specimens were subjected to freeze–thaw cycling. Notably, the results of this study indicate that the freeze–thaw damage to SFRC reduces AE signal activity at low frequencies.

关键词： steel fiber reinforced concrete     freeze–thaw cycling     Brazilian disc splitting test     acoustic emission technique     dynamic splitting tensile acoustic emission properties    

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Tensile properties

QI Dongming, SHAO Jianzhong, WU Minghua, NITTA Kohhei

《化学科学与工程前沿（英文）》 2008年 第2卷 第4期   页码 396-401 doi: 10.1007/s11705-008-0077-1

摘要： A novel phenolic rigid organic filler (KT) was used to modify isotactic polypropylene (iPP). The influence of KT particles on the tensile properties of PP/KT microcomposites was studied by uniaxial tensile test and the morphological structures of the stretched specimens were observed by scanning electron microscopy (SEM) and polarized optical microscopy (POM). We found that the Young’s modulus of PP/KT specimens increased with filler content, while the yield and break of the specimens are related to the filler particles size. The yield stress, the breaking stress and the ultimate elongation of PP/KT specimens were close to those of unfilled iPP specimens when the maximal filler particles size is less than a critical value, which is 7 ?m at a crosshead speed of 10 mm/min and 3 ?m at 200 mm/min, close to that of glass bead but far more than those of other rigid inorganic filler particles. The interfacial interaction was further estimated from yield stress, indicating that KT particles have a moderate interfacial interaction with iPP matrix. Thus, the incorporation of small KT particles can reinforce iPP matrix and simultaneously cause few detrimental effects on the other excellent tensile properties of iPP matrix, due to their organic nature, higher specific area, solid true-spherical shape and the homogenous dispersion of the ROF particles in microcomposites.

关键词： maximal     uniaxial tensile     unfilled     excellent tensile     influence    

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Split-order consolidation optimization for online supermarkets: Process analysis and optimization models

《工程管理前沿（英文）》   页码 499-516 doi: 10.1007/s42524-022-0221-5

摘要： The large-scale online supermarket is a newly emerging online retailing mode which brings great convenience to people. Online supermarkets are characterized by having large amounts of daily orders with potentially multiple items, diverse delivery times, and a high order-split rate. Multiple shipments for one order caused by order splitting result in high cost and disturbance and a large number of discarded consumable packages at online retailers and customers, causing severe damage to the environment. Accordingly, research on split-order consolidation fulfilment is critical for the advancement of the practice and theory in the context of highly complex online retailing. This paper first analyzes the characteristics and the challenges associated with the split-order consolidation problem that online supermarket is confronting and summarizes the new operational process of split-order consolidation fulfilment. Then, a time–space network optimization model is built, and its corresponding solution algorithm is presented to solve the questions of where and when to consolidate the split orders. Finally, the computation results of the numerical experiments are provided to verify the effectiveness of the algorithm, and a sensitivity analysis of the relevant parameters is performed. This work highlights the effect of order consolidation processes and fulfilment methods on the order fulfilment decision-making for online supermarkets. The purpose of this article is to help pave the way for more effective online supermarket management and order implementation.

关键词： online supermarkets     split-order consolidation     time–space network     genetic algorithm    

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Influence of the field humiture environment on the mechanical properties of 316L stainless steel repaired with Fe314

Lianzhong ZHANG, Dichen LI, Shenping YAN, Ruidong XIE, Hongliang QU

《机械工程前沿（英文）》 2018年 第13卷 第4期   页码 513-519 doi: 10.1007/s11465-018-0503-0

摘要：

The mechanical properties of 316L stainless steel repaired with Fe314 under different temperatures and humidities without inert gas protection were studied. Results indicated favorable compatibility between Fe314 and 316L stainless steel. The average yield strength, tensile strength, and sectional contraction percentage were higher in repaired samples than in 316L stainless steel, whereas the elongation rate was slightly lower. The different conditions of humiture environment on the repair sample exerted minimal influence on tensile and yield strengths. The Fe314 cladding layer was mainly composed of equiaxed grains and mixed with randomly oriented columnar crystal and tiny pores or impurities in the tissue. Results indicated that the hardness value of Fe314 cladding layer under different humiture environments ranged within 419–451.1 HV0.2. The field humiture environment also showed minimal impact on the average hardness of Fe314 cladding layers. Furthermore, 316L stainless steel can be repaired through laser cladding by using Fe314 powder without inert gas protection under different temperatures and humidity environments.

关键词： laser cladding     repaired performance     tensile strength     temperature and humidity environment    

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An artificial neural network model on tensile behavior of hybrid steel-PVA fiber reinforced concrete

Fangyu LIU, Wenqi DING, Yafei QIAO, Linbing WANG

《结构与土木工程前沿（英文）》 2020年 第14卷 第6期   页码 1299-1315 doi: 10.1007/s11709-020-0712-6

摘要： The tensile behavior of hybrid fiber reinforced concrete (HFRC) is important to the design of HFRC and HFRC structure. This study used an artificial neural network (ANN) model to describe the tensile behavior of HFRC. This ANN model can describe well the tensile stress-strain curve of HFRC with the consideration of 23 features of HFRC. In the model, three methods to process output features (no-processed, mid-processed, and processed) are discussed and the mid-processed method is recommended to achieve a better reproduction of the experimental data. This means the strain should be normalized while the stress doesn’t need normalization. To prepare the database of the model, both many direct tensile test results and the relevant literature data are collected. Moreover, a traditional equation-based model is also established and compared with the ANN model. The results show that the ANN model has a better prediction than the equation-based model in terms of the tensile stress-strain curve, tensile strength, and strain corresponding to tensile strength of HFRC. Finally, the sensitivity analysis of the ANN model is also performed to analyze the contribution of each input feature to the tensile strength and strain corresponding to tensile strength. The mechanical properties of plain concrete make the main contribution to the tensile strength and strain corresponding to tensile strength, while steel fibers tend to make more contributions to these two items than PVA fibers.

关键词： artificial neural network     hybrid fiber reinforced concrete     tensile behavior     sensitivity analysis     stress-strain curve    

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标题 作者 时间 类型 操作

Experimental investigation on mechanical properties of binary and ternary blended pervious concrete

Rekha SINGH, Sanjay GOEL

期刊论文

考虑垫片形状和尺寸效应的珊瑚混凝土劈裂抗拉性能的三维细观研究

吴彰钰, 张锦华, 余红发, 方秦, 麻海燕, 陈力

期刊论文

Behavior of steel fiber–reinforced high-strength concrete at medium strain rate

Chujie JIAO, Wei SUN, Shi HUAN, Guoping JIANG

期刊论文

Effect of size on biaxial flexural strength for cement-based materials by using a triangular plate method

Hakan T TURKER

期刊论文

Achieving High Strength and Tensile Ductility in Pure Nickel by Cryorolling with Subsequent Low-Temperature

Zhide Li,Hao Gu,Kaiguang Luo,Charlie Kong,Hailiang Yu,

期刊论文

Characterization of the tensile properties of friction stir welded aluminum alloy joints based on axial

Biranchi PANDA,A. GARG,Zhang JIAN,Akbar HEIDARZADEH,Liang GAO

期刊论文

Fresh and hardened properties of high-strength concrete incorporating byproduct fine crushed aggregate

Dammika P. K. WELLALA, Ashish Kumer SAHA, Prabir Kumar SARKER, Vinod RAJAYOGAN

期刊论文

Quantification of coarse aggregate shape in concrete

Xianglin GU,Yvonne TRAN,Li HONG

期刊论文

Enhanced solution representations for vehicle routing problems with split deliveries

期刊论文

performance with high compression ratio based on knock suppression using Miller cycle with boost pressure and split

Haiqiao WEI, Jie YU, Lei ZHOU

期刊论文

Acoustic emissions evaluation of the dynamic splitting tensile properties of steel fiber reinforced concrete

期刊论文

Tensile properties

QI Dongming, SHAO Jianzhong, WU Minghua, NITTA Kohhei

期刊论文

Split-order consolidation optimization for online supermarkets: Process analysis and optimization models

期刊论文

Influence of the field humiture environment on the mechanical properties of 316L stainless steel repaired with Fe314

Lianzhong ZHANG, Dichen LI, Shenping YAN, Ruidong XIE, Hongliang QU

期刊论文

An artificial neural network model on tensile behavior of hybrid steel-PVA fiber reinforced concrete

Fangyu LIU, Wenqi DING, Yafei QIAO, Linbing WANG

期刊论文