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Investigation of the interior RC beam-column joints under monotonic antisymmetrical load

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Frontiers of Structural and civil engineering 2019年第6期13卷 1474-1494页

作者： Fei GAO Zhiqiang TANG Biao HU Junbo CHEN Hongping ZHU Jian MA School of civil engineering and Mechanics Huazhong University of Science and TechnologyWuhan 430074China guangdong provincial key l aboratory of durability for marine civil engineering Shenzhen UniversityShenzhen 518060China Department of civil and Environmental engineering The Hong Kong Polytechnic UniversityHong Kong 999077China

The paper presents numerical findings of reinforced concrete interior beam-column joints under monotonic antisymmetrical *** finite element models considered compression and tension damage were calibrated by test results in terms of the load-displacement,failure modes,and strains of longitudinal *** emphasis was put on studying the effects of hoop reinforcement ratio in joint core and the axial compression ratio on the responses of the *** results show that,in addition to the truss and strut-and-tie mechanisms,the confinement mechanism also existed in the joint core.A certain amount of stirrup is not only able to enhance the confinement in joint core,undertake a part of shear force and thus to increase the shear capacity,prevent the outward buckling of steel bars in column,improve the stress distribution in joint core,delay cracking and restrain the propagation of cracks,but also to increase the yield load,decrease the yield displacement of beam and improve the joint ***,excessive horizontal stirrups contribute little to the joint *** a certain range,larger axial compression ratio is beneficial for the joint mechanical behavior,while it is negative when axial compression ratio is too large.

关键词： RC beam-column joint reinforcement ratio in joint core axial compression ratio finite element test

A novel and promising engineering application of carbon dots:Enhancing the chloride binding performance of cement

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Chinese Chemical letters 2024年第6期35卷 409-416页

作者： Wu-Jian long Yang Yu Chuang He guangdong provincial key laboratory of durability for marine civil engineering Key Lab of Coastal Urban Resilient InfrastructureMOECollege of Civil and Transportation EngineeringShenzhen UniversityShenzhen 518060China

Corrosion of reinforcement induced by chloride invasion is extensively considered as the dominating deterioration mechanism of reinforced concrete(RC)structures,leading to serious safety hazards and tremendous economic ***,it still lacks well dispersive and cost-efficient nanomaterials to improve the anti-chloride-corrosion ability of RC ***,specific carbon dots(CDs)with high dispersity and low cost are deliberately designed,successfully prepared by hydrothermal processing,and then firstly applied to immensely enhance chloride binding performance of cement,thereby contributing to suppressing the corrosion of ***,the tailored CDs are composed of the carbon core with highly crystalline sp^(2)C structures and oxygen-containing groups connecting on the carbon core;The typical equilibrium test confirms that with respect to that of the blank cement paste,the chloride binding capacity of cement paste involving 0.2 wt%(by weight of cement)CDs is increased by 109% after 14-day exposure to 3 mol/l Na Cl solution;according to comprehensive analyses of phase compositions,the chloride binding mechanism of CDs-modified cement is rationally attributed to the fact that the incorporation of CDs advances the formation of calcium silicate hydrate(C-S-H)gels and Friedel's salt(Fs),thus enormously enhancing the physically adsorbed and chemically bound chloride ions of cement *** work not only firstly provides a novel high-dispersity and low-cost nanomaterial toward the durability enhancement of RC structures,but also broadens the application of CDs in the field of engineering,conducing to stimulating their industrialization development.

关键词： Carbon dots Chloride binding Cement Chloride binding mechanism Friedel’s salt

Simplified design of nonlinear damper parameters and seismic responses for long-span cable-stayed bridges with nonlinear viscous dampers

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Frontiers of Structural and civil engineering 2024年第7期18卷 1103-1116页

作者： Huihui lI lifeng lI Rui HU Meng YE College of civil and Transportation engineering Shenzhen UniversityShenzhen 518060China guangdong provincial key laboratory of durability for marine civil engineering Shenzhen UniversityShenzhen 518060China College of civil engineering Hunan UniversityChangsha 410082China

Viscous dampers are widely used as passive energy dissipation devices for long-span cable-stayed bridges for mitigation of seismic load-induced ***,complicated finite element(FE)modeling,together with repetitive and computationally intensive nonlinear time-history analyses(NTHAs)are generally required in conventional design *** streamline the preliminary design process,this paper developed a simplified longitudinal double degree of freedom model(DDFM)for single and symmetric twin-tower cable-stayed *** on the proposed simplified longitudinal DDFM,the analytical equations for the relevant mass-and stiffness-related parameters and longitudinal natural frequencies of the structure were derived by using analytical and energy *** of the relationship between the nonlinear viscous damper parameters and the equivalent damping ratio was achieved through the equivalent linearization ***,the analytical equations of longitudinal seismic responses for long-span cable-stayed bridges with nonlinear viscous dampers were *** on the developed simplified DDFM and suggested analytical equations,this paper proposed a simplified calculation framework to achieve a simplified design method of nonlinear viscous damper ***,the effectiveness and applicability of the developed simplified longitudinal DDFM and the proposed calculation framework were further validated through numerical analysis of a practical cable-stayed ***,the results indicated the following.1)For the obtained fundamental period and longitudinal stiffness,the differences between results of the simplified longitudinal DDFM and numerical analysis were only 2.05%and 1.5%,respectively.2)Relative calculation errors of the longitudinal girder-end displacement and bending moment of the bottom tower section of the bridge obtained from the simplified longitudinal DDFM were limited to less than 25%.3)The equivalent damping ratio of nonline

关键词： cable-stayed bridges viscous dampers simplified analytical model equivalent damping ratio seismic mitigation

Fused structures for safer and more economical constructions

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Frontiers of Structural and civil engineering 2020年第1期14卷 1-9页

作者： Yu-Fei WU Ying-Wu ZHOU Biao HU Xiaoxu HUANG Scott SMITH School of engineering RMIT UniversityMelbourneVIC 3001Australia guangdong provincial key laboratory of durability for marine civil engineering Shenzhen UniversityShenzhen 518061China School of civil Environmental and Mining EngineeringThe University of AdelaideSouth Australia 5005Australia

Safety margin and construction costs are two conflicting goals for a *** providing a fuse in a structure that is triggered at a certain level of over-loading,further increase of loading is prohibited and failure of the structure is changed to a safer *** overloading is controlled and a safer failure mode is enforced,a fused structure requires a smaller safety factor thus leading to more economical construction without compromising *** use of a fuse will also facilitate safer use of advanced construction materials such as fiber-reinforced polymer(FRP)*** this case,a fuse can transfer the sudden and dangerous failure mode associated with brittle FRP debonding or rupture to a safe and ductile failure mode at the fuse *** paper introduces a new type of fused structure as well as an associated design philosophy and approach,in addition to examples of engineering applications.

关键词： fused structures structural fuse fiber-reinforced polymer concrete

Chemical Modifications of layered Double Hydroxides in the Supercapacitor

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Energy & Environmental Materials 2020年第3期3卷 346-379页

作者： Chuan Jing Biqin Dong Yuxin Zhang State key laboratory of Mechanical Transmissions College of Materials Science and EngineeringChongqing UniversityChongqing 400044China guangdong provincial key laboratory of durability for marine civil engineering Shenzhen UniversityShenzhen 518060China

layered double hydroxides are one class or kind of 2 D layered materials that are considered promising for use in the *** there have been many studies on the structure,composition,properties,and electrode fabrication of layered double hydroxides,none summarize the effects of various modification methods on the structure and performance of layered double hydroxides in the *** a bid to fill this gap,in this review,we summarize the progress of modification methods such as exfoliation,intercalation,vacancy,doping,phase transformation,and composition regulation of layered double hydroxides in the field of the supercapacitor and put forward some opinions regarding the progress of research on the methods used in modifying the layered double hydroxides.

关键词： 2D materials chemical modifications layered double hydroxide supercapacitor

Modeling the Synergetic Effect of Various Factors on Chloride Transport in Nonsaturated Concrete

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Journal of Wuhan University of Technology(Materials Science) 2016年第6期31卷 1336-1346页

作者：张小刚 lU Zhaohui 王淑萍 ZHOU Tianhai XING Feng guangdong provincial key laboratory of durability for marine civil engineering College of Civil Engineering Shenzhen University Shenzhen 518060 China National engineering laboratory for High Speed Railway Construction School of Civil Engineering Central South University Changsha 410075 China College of Materials Science and engineering Chongqing University Chongqing 400045 China

Diffusion has been systematically described as the main mechanism of chloride transport in reinforced concrete（RC） structure, especially when the concrete is in a saturated state. However, the single mechanism of diffusion is not able to describe the actual chloride ingress in the nonsaturated concrete. Instead, it is dominated by the interaction of diffusion and convection. With the synergetic effects of various factors taken into account, this study aimed to modify and develop an analytical convection- diffusion coupling model for chloride transport in nonsaturated concrete. The model was verified by simulation of laboratory tests and field measurement. The results of comparison study demonstrate that the analytical model developed in this study is efficient and accurate in predicting the chloride profiles in the nonsaturated concrete.

关键词： RC structures nonsaturated concrete chloride transport synergetic effect analytical convection-diffusion model influence factors

Corrosion inhibition of layered double hydroxides for metal-based systems

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Nano Materials Science 2021年第1期3卷 47-67页

作者： Chuan Jing Biqin Dong Aikifa Raza Tiejun Zhang Yuxin Zhang State key laboratory of Mechanical Transmissions College of Materials Science and EngineeringChongqing UniversityChongqing400044PR China guangdong provincial key laboratory of durability for marine civil engineering Shenzhen UniversityShenzhen518060PR China Department of Mechanical engineering Masdar InstituteKhalifa University of Science and TechnologyP.O.Box 127788Abu DhabiUnited Arab Emirates

layered double hydroxide(lDH),a kind of 2D layered materials,has been recognized as the promising anticorrosion materials for metal and its *** microstructure,physical/chemical properties,usage in corrosion inhibition and inhibition performance of lDH have been studied separately in open ***,there is a lack of a complete review to summarize the status of lDH technology and the potential R&D opportunities in the field of corrosion *** addition,the challenges for lDH in corrosion inhibition of metal-based system have not been summarized ***,we review recent advances in the rational design of lDH for corrosion inhibition of metal-based system(*** alloy,Al alloy,steel and concrete)and high-throughput anticorrosion materials *** evaluating the physical/chemical properties,usage in metal-based system and the corrosion inhibition mechanism of lDH,we highlight several important factors of lDH for anticorrosion performance and common features of lDH in applying different metal ***,we provide our perspective and recommendation in this field,including high-throughput techiniques for combinatorial compositional design and rapid synthesis of anticorrosion alloys,with the goal of accelerating the development and application of lDH in corrosion inhibition of metal-based system.

关键词： layered double hydroxide Corrosion inhibition Magnesium alloy Aluminum alloy Steel Concrete

The Pore Structure of Phosphoaluminate Cement

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Open Journal of Composite Materials 2012年第3期2卷 104-112页

作者： Weilun Wang Peng liu Ming Zhang Jiashan Hu Feng Xing guangdong provincial key laboratory of durability for marine civil engineering Shenzhen University Shenzhen China School of civil engineering and Architecture Central South University Changsha China

The effects of curing time and water-to-cement ratio (W/C) on the pore structure of phosphoaluminate cement (PAC) paste are here presented. Based on the adsorption and condensation theory, the adsorption isotherm of hardened paste was tested using the Brunauer-Emmett-Teller (BET) nitrogen adsorption method. The phase composition and morphology of hydration products cured at different times were analyzed using X-ray diffraction (XRD), and a hydration heat test instrument (HHT) was employed to determine the heat of hydration. The effects of curing time and W/C on the pore structure of PAC are significant. The adsorption isotherm is fitted to the second category based on the Brun-auer- Deming-Deming-Teller (BDDT) classification system. Adsorption volume was found to increase with W/C and then decrease with age. The hysteresis loop of PAC is fitted to the H3 type based on International Union of Pure and Applied Chemistry (IUPAC) guidelines, and the adsorption volume and area enclosed by the hysteresis loop were found to increase with W/C and then decrease with age. BET surface and saturated adsorbed volume of PAC both increase with W/C and decrease with curing time, which is attributable to the greater hydration that produces and changes the characteristics of the pore structure.

关键词： Phosphoaluminate Cement Pore Structure Adsorption Curing Time

Hydrological Response to Climate and land Use Changes in the Dry–Warm Valley of the Upper Yangtze River

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engineering 2022年第12期19卷 24-39页

作者： Congcong li Yanpeng Cai Zhong li Qianqian Zhang lian Sun Xinyi li Pengxiao Zhou State key laboratory of Water Environment Simulation School of EnvironmentBeijing Normal UniversityBeijing 100875China guangdong provincial key laboratory of Water Quality Improvement and Ecological Restoration for Watersheds Institute of Environmental and Ecological EngineeringGuangdong University of TechnologyGuangzhou 510006China Department of civil engineering McMaster UniversityHamiltonON L8S 4L7Canada Southern marine Science and engineering guangdong laboratory(Guangzhou) Guangzhou 511458China Chengdu University of Information Technology Chengdu 610225China

The hydrological process in the dry–warm valley of the mountainous area of southwest China has unique characteristics and has attracted scientific attention *** that this is an area with fragile ecosystems and intensive water resource conflicts in the upper reaches of the Yangtze River,a systematic identification of its hydrological responses to climate and land use variations needs to be *** this study,MIKE SHE was employed and calibrated for the Anning River Basin in the dry–warm ***,a deep learning neural network model of the long short-term memory(lSTM)and a traditional multi-model ensemble mean(MMEM)method were used for an ensemble of 31 global climate models(GCMs)for climate *** cellular automata–Markov model was implemented to project the spatial pattern of land use considering climatic,social,and economic *** sets of climate projections and three sets of land use projections were generated and fed into the MIKE SHE to project hydrologic responses from 2021 to *** the calibration and first validation periods of the daily simulation,the coefficients of determination(R)were 0.85 and 0.87 and the Nash–Sutcliffe efficiency values were 0.72 and 0.73,*** advanced lSTM performed better than the traditional MMEM method for daily temperature and monthly *** average monthly temperature projection under representative concentration pathway 8.5(RCP8.5)was expected to be slightly higher than that under RCP4.5;this is contrary to the average monthly precipitation from June to *** variations in streamflow and actual evapotranspiration(ET)were both more sensitive to climate change than to land use *** was no significant relationship between the variations in streamflow and the ET in the study *** work could provide general variation conditions and a range of hydrologic responses to complex and changing environments,thereby assisting with stochastic uncertainty a

关键词： Dry-warm valley Hydrologic simulation Multi-ensemble GCMs Climate change land use variations