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Frontiers of Structural and Civil Engineering 2021年第3期15卷 576-594页

作者： Peng ZHU Jiajing XU wenjun qu Department of Structural Engineering Tongji UniversityShanghai200092China School of Transportation and Civil Engineering Nantong UniversityNantong226019China

Reinforced concrete beams consisting of both steel and glass-fiber-reinforced polymer rebars exhibit excellent strength,serviceability,and ***,the fatigue shear performance of such beams is ***,beams with hybrid longitudinal bars and hybrid stirrups were designed,and fatigue shear tests were *** specimens that failed by fatigue shear,all the glass-fiber-reinforced polymer stirrups and some steel stirrups fractured at the critical diagonal *** the specimen that failed by the static test after 8 million fatigue cycles,the static capacity after fatigue did not significantly decrease compared with the calculated *** initial fatigue level has a greater influence on the crack development and fatigue life than the fatigue level in the later *** fatigue strength of the glass-fiber-reinforced polymer stirrups in the specimens was considerably lower than that of the axial tension tests on the glass-fiber-reinforced polymer bar in air and beam-hinge tests on the glass-fiber-reinforced polymer bar,and the failure modes were ***-fiber-reinforced polymer stirrups were subjected to fatigue tension and shear,and failed owing to shear.

关键词： fatigue shear hybrid stirrups hybrid reinforcement fiber-reinforced polymer

Long-term effects of electrochemical realkalization on carbonated concrete

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Frontiers of Structural and Civil Engineering 2020年第1期14卷 127-137页

作者： Peng ZHU Ji ZHANG wenjun qu College of Civil Engineering Tongji UniversityShanghai 200092China Key Laboratory of Performance Evolution and Control for Engineering Structures Shanghai 200092China

The long-term effects of electrochemical realkalization on carbonated reinforced concrete with a W/C ratio of 0.65 were *** out of 16 carbonated specimens had been subjected to realkalization seven years ago,and the alkalinity of the concrete,the electrochemical characters(corrosion current density and potential)of the specimens and the corrosion conditions of the steel bars were *** of different specimens and also at different time(4,10,13 months and 7 years after realkalization)were *** to the phenolphthalein and pH meter test,the alkalinity of the concrete had disappeared after seven *** on the potentiodynamic polarization test,various corrosion conditions had developed on the steel bars,which was verified by visual *** bars were in the depassivated state,and their corrosion current densities increased significantly after seven *** developed in some of the specimens,and the diverse compactness of concrete and excessive current of realkalization were considered to be possible *** effects of the realkalization treatment vanished after seven years.

关键词： realkalization concrete carbonation polarization curve corrosion

Stress-strain relationship for reactive powder concrete with recycled powder under uniaxial compression

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Frontiers of Structural and Civil Engineering 2024年第7期18卷 1015-1027页

作者： Peng ZHU Yunming ZHU wenjun qu Liyu XIE College of Civil Engineering Tongji UniversityShanghai 200092China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji UniversityShanghai 200092China

The recycled powder(RP)from construction wastes can be used to partially replace cement in the preparation of reactive powder *** this paper,reactive powder concrete mixtures with RP partially replacing cement,and natural sand instead of quartz,are *** curing is used,instead of steam curing that is normally requested by standard for reactive powder *** influences of RP replacement ratio(0%,10%,20%,30%),silica fume proportion(10%,15%,20%),and steel fiber proportion(0%,1%,2%)are *** effects of RP,silica fume,and steel fiber proportion on compressive strength,elastic modulus,and relative absorption energy are analyzed,and theoretical models for compressive strength,elastic modulus,and relative absorption energy are established.A constitutive model for the uniaxial compressive stress-strain relationship of reactive powder concrete with RP is *** the increase of RP replacement ratio from 0% to 30%,the compressive strength decreases by 42% and elastic modulus decreases by 24%.

关键词： recycled powder reactive powder concrete elastic modulus relative absorbed energy stress-strain relationship

Model of Underground Ant Nest Structure Using Static and Dynamic Finite Element Analysis

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Acta Mechanica Solida Sinica 2018年第6期31卷 717-730页

作者： wenjun qu Wei Zhou Peng Zhu Zhi Zhang Department of Structural Engineering Tongji University Shanghai 200092 China The High School Affiliated with Shanghai University Shanghai 200444 Chinch

This paper focuses on the structural characteristics of ant nests,which are complex *** underground ant nests generally have good air circulation,pressure resistance, waterproof properties,thermal insulation and a favorable temperature and relative humidity. Additionally,ant nests are often surrounded by trees and other natural *** this study, the natural underground ant nests of Iridomyrmex anceps were gathered from different collection *** cutting and frozen computer numerical control milling were performed on the ant nests in a *** internal structure of each nest was measured and recorded,and then, the 2D and 3D numerical structure models of the Iridomyrmex anceps nest were *** static and dynamic simulation analysis of an underground ant nest structure was performed by using finite element analysis software (ABAquS),and the mechanical properties of the ant nest were *** underground ant nest structure effectively resisted the additional stress due to external static and live loads,and the ant nest was not completely destroyed.

关键词： Underground ant nest Iridomyrmex anceps Frozen CNC milling Finite element analysis Static simulation Dynamic simulation

Osmium isotope of the Co-rich crust from seamount Allison, central Pacific and its use for determination of growth hiatus and growth age

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Science China Earth Sciences 2008年第10期51卷 1446-1451页

作者： MENG XianWei LIU YanGuang qu wenjun SHI XueFa Key Laboratory of Marine Sedimentology&Environmental Geology First Institute of OceanographyState Oceanic AdministrationQingdao 266061China National Research Center for Geoanalysis Beijing 100037China

Based on its microstructure, Co-rich crust A1-1 from seamount Allison, central Pacific, was scraped at averaged interval of 1.3 mm to measure osmium isotopic composition, and subsequently to establish the 187Os/188Os profile of scraping section of the crust. By observing the variation of 187Os/188Os under 10Be chronology and matching it to the well-known seawater Os isotope evolution of the past 40 Ma, two growth hiatuses (H1 and H2) occurring in the periods respectively between 13.6 and 29.6 Ma and between 8 and 9.8 Ma in the crust were recognized. According to the two hiatuses, the dating scheme for each scraped layer of the crust was suggested. For the upper layers younger than 6.8Ma, their growth ages were calibrated under 10Be chronology; for the lower layers older than 6.8Ma, their growth ages were obtained from 187Os/188Os evaluation curve by linear interpolation. Hereby, the age for the most inner layer of the crust was determined to be 39.5 Ma. H1 and H2 exactly correspond to the boundary between phosphatization and non-phosphatization and volcanic ash layer in the crust, respectively.

关键词： seamount Allison Co-rich crust Os isotope growth hiatus

Geochemistry of Platinum Group and Rare Earth Elements of the Polymetallic Layer in the Lower Cambrian,Weng'an,Guizhou Province

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Acta Geologica Sinica(English Edition) 2009年第3期83卷 618-627页

作者： FU Yong WU Chaodong GUAN Ping qu wenjun CHEN Jiafu Key Laboratory of Orogenic Belts and Crustal Evolution MOE Peking University Beijing 100871 China National Research Center of Geoanalysis Beijing 100037 China

The black shales of the Lower Cambrian Niutitang Formation in Weng＇an, on the Yangtze platform of south China, contain voluminous polymetallic sulfide deposits. A comprehensive geochemical investigation of trace, rare earth, and platinum group elements （PGE） has been undertaken in order to discuss its ore genesis and correlation with the tectono-depositional setting. The ore-bearing layers enrich molybdenum （Mo）, nickel （Ni）, vanadium （V）, lead （Pb）, strontium （Sr）, barium （Ba）, uranium （U）, arsenic （As）, and rare earth elements （REE） in abundance. High uranium/ thorium （U/Th） ratios （U/Th〉I） indicated that mineralization was mainly influenced by the hydrothermal process. The 8U value was above 1.9, showing a reducing sedimentary condition. The REE patterns showed high enrichment in light rare earth elements （LREE）（heavy rare earth elements （HREE）（LREE/HREE=5-17）, slightly negative europium （Eu） and cerium （Ce） anomalies （δEu=0.81- 0.93）, and positive Ce anomalies （δCe=0.76-1.12）. PGE abundance was characterized by the PGE-type distribution patterns, enriching platinum （Pt）, palladium （Pd）, ruthenium （Ru） and osmium （Os）. The Pt/Pd ratio was 0.8, which is close to the ratios of seawater and ultramafic rocks. All of these geochemical features suggest that the mineralization was triggered by hydrothermal activity in an extensional setting in the context of break-up of the Rodinian supercontinent.

关键词： geochemistry polymetallic layer hydrothermal activity Lower Cambrian

The relationship between the growth process of the ferromanganese crusts in the Pacific seamount and Cenozoic ocean evolvement

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Science China Earth Sciences 2009年第8期52卷 1091-1103页

作者： DING Xuan GAO LianFeng FANG NianQiao qu wenjun LIU Jian LI JiangShan School of Marine Science China University of GeosciencesBeijing 100083China College of Resources and Environments Hebei Polytechnic UniversityTangshan 063009China National Geologic Experiment and Test Center Beijing 100037China Guangzhou Marine Geological Survey Guangzhou 510075China

Base on the Os isotope stratigraphy together with the empirical growth rate models using Co concentrations, the growth ages of the ferromanganese crusts MHD79 and MP3D10 distributed in the seamount of Pacific are confirmed. Through the contrast and research on the previous achievements including ODP Leg 144 and the crusts CD29-2, N5E-06 and N1-15 of the seamount of the Central Pacific, the uniform five growth and growth hiatus periods of them are found, and closely related to the Cenozoic ocean evolvement process. In the Paleocene Carbon Isotope Maximum (PCIM), the rise of the global ocean productivity promoted the growth of the seamount crust; the first growth hiatus (I) of the ferromanganese crust finished. In the Paleocene-Eocene Thermal Maximum (PETM), though the vertical exchange of seawater was weakened, the strong terrestrial chemical weathering led to the input of a great amount of the terrigenous nutrients, which made the bioproductivity rise, so there were no crust hiatuses. During 52-50 Ma, the Early Eocene Optimum Climate (EECO), the two poles were warm, the latitudinal temperature gradient was small, the wind-driven sea circulation and upwelling activity were weak, the terrestrial weathering was also weakened, the open ocean bioproductivity decreased, and the ferromanganese crust had growth hiatus again (II). From early Middle Eocene-Late Eocene, Oligocene, it was a long-term gradually cooling process, the strengthening of the sea circulation and upwelling led to a rise of bioproductivity, and increase of the content of the hydrogenous element Fe, Mn and Co and the biogenous element Cu, Zn, so that was the most favorable stage for the growth of ferromanganese crust (growth periods III and IV) in the studied area. The hiatus III corresponded with the Eocene-Oligocene boundary, is inferred to relate with the global climate transformation, celestial body impact event in the Eocene-Oligocene transition. From the early to the middle Miocene, a large-scale gr

关键词： Pacific seamount ferromanganese crust growth period and growth hiatus period Cenozoic ocean evolvement

Re-Os isotope dating of molybdenites in the Huang-shaping Pb-Zn-W-Mo polymetallic deposit, Hunan Province, South China and its geological significance

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Science China Earth Sciences 2007年第4期50卷 519-526页

作者： YAO JunMing HUA RenMin qu wenjun QI HuaWen LIN JinFu DU AnDao State Key Laboratory of Crust-Mantle Evolution and Mineralization Department of Earth SciencesNanjing UniversityNanjing 210093China Institute of Rock and Mineral Analysis Chinese Academy of Geological SciencesBeijing 100037China Institute of Geochemistry Chinese Academy of SciencesGuiyang 550002China Department of Resources and Environment Engineering Guilin Institute of TechnologyGuilin 541004China

The large-scale Huangshaping Pb-Zn-W-Mo polymetallic deposit is located in the central Nanling min- eralization zone, South China. Six molybdenite samples from the Huangshaping deposit were selected for Re-Os isotope measurement in order to define the mineralization age of the deposit. It yields a Re-Os isochron age of 154.8±1.9 Ma (2σ ), which is in accordance with the Re-Os model ages of 150.9― 156.9 Ma. This age is about 7 Ma younger than their host granite porphyry, which was dated as 161.6±1.1 Ma by zircon U-Pb method using LA-ICPMS. All these ages demonstrate that the Huang- shaping granite and related Pb-Zn-W-Mo deposit occurred in the middle Yanshanian period, when many other granitoid and related ore deposits emplaced and formed, e.g. the Qitianling granite and Furong tin deposit, the Qianlishan granite and giant Shizhuyuan W-Sn-Mo-Bi deposit and Jinchuantang Sn-Bi deposit in the nearby area. They constitute the main part of the magmatic-metallogenic belt of southern Hunan, and represent the large-scale metallogeny in middle Yanshanian in the area. The lower rhenium content in molybdenite of Huangshaping deposit suggests that the ore-forming material was mainly of crust origin.

关键词： Re-Os isotope dating molybdenite Huangshaping deposit granite southern Hunan Province

New Re-Os Isotopic Constrains on the Formation of the Metalliferous Deposits of the Lower Cambrian Niutitang Formation

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Journal of Earth Science 2016年第2期27卷 271-281页

作者： Yong Fu Lin Dong Chao Li wenjun qu Haoxiang Pei Wenlang Qiao Bing Shen College of Resource and Environmental Engineering Guizhou University Guiyang 550012 China Key Laboratory of Metallogeny and Mineral Assessment Institute of Mineral Resources Chinese Academy of Geological Sciences Beijing 100037 China Key Laboratory of Orogenic Belts and Crustal Evolution MOE School of Earth and Space Science Peking University Beijing 100871 China Re-Os lab National Research Center for Geoanalysis Chinese Academy of Geological Sciences Beijing 100037 China Institute of Guizhou Geological Survey Guiyang 550004 China

The Terreneuvian Epoch（541-521 Ma）is also an important period for metallogenesis in South China, as was represented by the widespread occurrences of Ni-Mo polymetallic layers on the antecedent shallow platform margin and the V-enriched black shales in deeper slope-basin settings. In this study, we have measured Re-Os isochron ages of Ni-Mo polymetallic layers（Songlin, Niuchang, Sancha, Chuanpengwan）, V-rich black shales（Bahuang）, and non-metalliferous black shales（Shuidong） in the basal Niutitang Formation in Guizhou and Hunan province, South China. The Ni-Mo polymetallic layers and V-enriched black shales have similar Re-Os isochron ages, suggesting concurrent deposition of these two types of metalliferous ores. This suggestion is consistent with the traditional stratigraphic correlation by using the nodular phosphorite bed directly underlying these metalliferous layers as a stratigraphic marker. Furthermore, the metalliferous ores and non-metalliferous black shales have similar initial ^（187）Os/^（188） Os ratios of 0.8-0.9, arguing for a dominant seawater origin with minor contribution of hydrothermal activity. Furthermore, Re-Os isotopic data also imply that Ni-Mo and V ore might have derived from the same source. We suggest that the spatial distribution of metalliferous ores can be explained by the development of non-sulfidic anoxic-suboxic wedge（NSASW） in the slope-basin and sulfidic wedge in the previous platform margin. Upwelling of deep water first transects the mildly reduced, organic rich NSASW, in which V（V） is reduced to V（IV）, and is preferentially removed from seawater by organometallic complex formation. As a result, V-rich black shale deposits in the slope-basin of Yangtze Platform. Further movement of deep water into the sulfidic platform margin results in Ni-Mo polymetallic layer formation.

关键词： Niutitang Formation South China Ni-Mo polymetallic layer V-rich black shale Re-Osisochron ages.

Os isotope dating and growth hiatuses of Co-rich crust from central Pacific

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Science China Earth Sciences 2008年第10期51卷 1452-1459页

作者： LI JiangShan FANG NianQiao qu wenjun DING Xuan GAO LianFeng WU ChangHang ZHANG ZhenGuo School of Marine China University of GeosciencesBeijing 100083China Key Laboratory of Marine Sedimentology and Environmental Geology of State Oceanic Administration First Institute of Oceanog-raphyState Oceanic AdministrationQingdao 266061China Institute of Oceanology Chinese Academy of SciencesQingdao 266071China National Research Centre for Geoanalysis Beijing 100037China Hebei Polytechnic University Tangshan 063009China

Up to now, accurate determination of the growth age and hiatuses of the Co-rich crust is still a difficult work, which constrains the researches on the genesis, growth process, controlling factors, regional tectonics, paleo-oceanographic background, etc. of the Co-rich crust. This paper describes our work in determining the initial growth age of the Co-rich crust to be of the late Cretaceous Campanian Stage (about 75-80 Ma), by selecting the Co-rich crust with clear multi-layer structures in a central Pacific seamount for layer-by-layer sample analysis and using a number of chronological methods, such as Co flux dating, dating by correlation with 187Os/188Os evolution curves of seawater, and stratigraphic divi- sion by calcareous nannofossils. We have also discovered growth hiatuses with different time intervals in the early Paleocene, middle Eocene, late Eocene and early-middle Miocene, respectively. These re- sults have provided an important age background for further researches on the Co-rich crust growth process and the paleo-oceanographic environment evolution thereby revealed in the said region.

关键词： central Pacific Co-rich crust Os isotope dating growth hiatus