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Macrozoobenthic assemblages in relation to environments of the Yangtze-isolated lakes

Baozhu PAN, Haijun WANG, Hongzhu WANG, Zhaoyin WANG

Frontiers of Environmental Science & Engineering 2012, Volume 6, Issue 2,   Pages 246-254 doi: 10.1007/s11783-011-0381-8

Abstract: Macrozoobenthos are good indicators of water environment, and studies on macrozoobenthic assemblage characteristics

Keywords: macrozoobenthos     assemblage characteristics     environment analyses     macrophytic lake     algal lake    

Strain localization analyses of idealized sands in biaxial tests by distinct element method

Mingjing JIANG, Hehua ZHU, Xiumei LI,

Frontiers of Structural and Civil Engineering 2010, Volume 4, Issue 2,   Pages 208-222 doi: 10.1007/s11709-010-0025-2

Abstract: This paper presents a numerical investigation on the strain localization of an idealized sand in biaxial compression tests using the distinct element method (DEM). In addition to the dilatancy and material frictional angle, the principal stress field, and distributions of void ratio, particle velocity, and the averaged pure rotation rate (APR) in the DEM specimen are examined to illustrate the link between microscopic and macroscopic variables in the case of strain localization. The study shows that strain localization of the granular material in the tests proceeds with localizations of void ratio, strain and APR, and distortions of stress field and force chains. In addition, both thickness and inclination of the shear band change with the increasing of axial strain, with the former valued around 10–14 times of mean grain diameter and the later overall described by the Mohr-Coulomb theory.

Keywords: idealized sand     strain localization     numerical analyses     distinct element method (DEM)    

Exergy and exergoeconomic analyses for integration of aromatics separation with aromatics upgrading

Frontiers of Chemical Science and Engineering 2023, Volume 17, Issue 2,   Pages 183-193 doi: 10.1007/s11705-022-2192-9

Abstract: Exergy and exergoeconomic analyses are conducted to give insights in the splitting ratios of benzene,

Keywords: aromatics separation and upgrading     variant splitting ratios     total exergy destruction     total product unit cost    

Numerical and experimental analyses of methane leakage in shield tunnel

Frontiers of Structural and Civil Engineering   Pages 1011-1020 doi: 10.1007/s11709-023-0956-z

Abstract: Tunnels constructed in gas-bearing strata are affected by the potential leakage of harmful gases, such as methane gas. Based on the basic principles of computational fluid dynamics, a numerical analysis was performed to simulate the ventilation and diffusion of harmful gases in a shield tunnel, and the effect of ventilation airflow speed on the diffusion of harmful gases was evaluated. As the airflow speed increased from 1.8 to 5.4 m/s, the methane emission was diluted, and the methane accumulation was only observed in the area near the methane leakage channels. The influence of increased ventilation airflow velocity was dominant for the ventilation modes with two and four fans. In addition, laboratory tests on methane leakage through segment joints were performed. The results show that the leakage process can be divided into “rapid leakage” and “slight leakage”, depending on the leakage pressure and the state of joint deformation. Based on the numerical and experimental analysis results, a relationship between the safety level and the joint deformation is established, which can be used as guidelines for maintaining utility tunnels.

Keywords: shield tunnel     harmful gas leakage     numerical analysis     laboratory test    

Cohesive zone model-based analyses of localized leakage of segmentally lined tunnels

Frontiers of Structural and Civil Engineering 2023, Volume 17, Issue 4,   Pages 503-521 doi: 10.1007/s11709-023-0927-4

Abstract: This paper presents a novel approach for simulating the localized leakage behavior of segmentally lined tunnels based on a cohesive zone model. The proposed approach not only simulates localized leakage at the lining segment, but also captures the hydromechanically coupled seepage behavior at the segmental joints. It is first verified via a tunnel drainage experiment, which reveals its merits over the existing local hydraulic conductivity method. Subsequently, a parametric study is conducted to investigate the effects of the aperture size, stratum permeability, and spatial distribution of drainage holes on the leakage behavior, stratum seepage field, and leakage-induced mechanical response of the tunnel lining. The proposed approach yields more accurate results than the classical local hydraulic conductivity method. Moreover, it is both computationally efficient and stable. Localized leakage leads to reduced local ground pressure, which further induces outward deformation near the leakage point and slight inward deformation at its diametrically opposite side. A localized stress arch spanning across the leakage point is observed, which manifests as the rotation of the principal stresses in the adjacent area. The seepage field depends on both the number and location of the leakage zones. Pseudostatic seepage zones, in which the seepage rate is significantly lower than that of the adjacent area, appear when multiple seepage zones are considered. Finally, the importance of employing the hydromechanical coupled mechanism at the segment joints is highlighted by cases of shallowly buried tunnels subjected to surface loading and pressure tunnels while considering internal water pressure.

Keywords: segmentally lined tunnel     localized leakage     cohesive element     hydraulic behavior     numerical modeling    

Iterative finite element model of nonlinear viscoplastic analyses for blended granular porous media

WU Yuching, ZHU Cimian

Frontiers of Structural and Civil Engineering 2007, Volume 1, Issue 4,   Pages 464-473 doi: 10.1007/s11709-007-0063-6

Abstract: The iterative finite element model, in which an element is used to represent a single particle, is generated to analyze the global behavior of multiple-material aggregates of materially nonlinear viscoplastic particles. The genera

Keywords: nonlinear viscoplastic     iterative     behavior     multiple-material    

Image analyses for video-based remote structure vibration monitoring system

Yang YANG,Xiong (Bill) YU

Frontiers of Structural and Civil Engineering 2016, Volume 10, Issue 1,   Pages 12-21 doi: 10.1007/s11709-016-0313-6

Abstract: This paper presents system and analyses to monitor the vibration velocity and displacement field.

Keywords: structure health monitoring     velocity estimation     frame difference     PIV     optical-flow method    

A review of recent experimental investigations and theoretical analyses for pulsating heat pipes

Xin TANG, Lili SHA, Hua ZHANG, Yonglin JU

Frontiers in Energy 2013, Volume 7, Issue 2,   Pages 161-173 doi: 10.1007/s11708-013-0250-1

Abstract: current researches in the field are described from the viewpoint of experimental tests, theoretical analysesIn addition, it is also pointed out that the present theoretical analyses of the PHP are restricted byfurther development of two-phase flow theories, and are concentrated in the non-linear analyses.

Keywords: pulsating heat pipe (PHP)     flow visualization     nanofluids     nonlinear analysis    

Design and analyses of open-ended pipe piles in cohesionless soils

Yuan GUO,Xiong (Bill) YU

Frontiers of Structural and Civil Engineering 2016, Volume 10, Issue 1,   Pages 22-29 doi: 10.1007/s11709-016-0314-5

Abstract: Large open-ended pipe pile has been found to be advantageous for use in transportation projects. The current design method, however, is not adequately developed. To close this practice gap, this paper first summarized different design methods for open-ended pipe piles in sandy soils. A major factor for all the design codes is to properly account for the formation and effects of soil plug. The comparison indicates that there is a large variation in the base capacity evaluation among different methods due to the complex behaviors of soil plug. To close the knowledge gap, discrete element method (DEM) was used to simulate the soil plugging process and provide insight on the plugging mechanism. The simulation results show that the arching effect significantly increases the internal unit shear resistance along pipe piles. The porosity distribution and particle contact force distribution from DEM model indicate a large stress concentration occurs at the bottom of the soil plug. Besides, nearly 90% of the plug resistance is provided by the bottom half portion of the soil column. The soil-pile friction coefficient has a significant effect on the magnitude of plug resistance, with the major transition occurred for friction coefficient between 0.3 and 0.4.

Keywords: open-ended pipe pile     soil plug     DEM     base capacity    

Fatigue stress monitoring and analyses for steel box girder of Runyang Suspension Bridge

WANG Ying, LI Zhaoxia, WU Baijian

Frontiers of Structural and Civil Engineering 2008, Volume 2, Issue 3,   Pages 197-204 doi: 10.1007/s11709-008-0038-2

Abstract: The monitoring of fatigue stress of steel bridge is a key issue of bridge health monitoring and safety assessment. This paper aims to find out the strain history features of the girder components of Runyang Suspension Bridge (RYSB) under vehicle and environmental loading during its first year of service based on the strain-history data recorded by structural health monitoring system installed in the bridge. The fatigue stress spectrums of steel box girders under normal traffic load, heavy trucks and typhoon loads were studied as well as the correlation between varying strain and temperature based on real-time monitoring of temperature histories. The results show that, monitoring on local strain in health monitoring systems of RYSB can effectively provide the information on fatigue stresses. The range of the equivalent fatigue stress on the monitoring location of the bridge is currently low, mainly due to varying traffic loading and temperature. There exists significant correlation between varying temperature and mean value of fatigue stress. Effect of the passing of heavy trucks on bridge fatigue is quite significant since the value of the cumulative fatigue damage generated by heavy trucks is 10 to 100 times larger than that by normal traffic. Therefore, the effect on fatigue cumulative damage due to heavy trucks or overloaded vehicles needs to be monitored and paid much attention to.

Keywords: bridge     monitoring location     RYSB     traffic loading     information    

Deformation field and crack analyses of concrete using digital image correlation method

Yijie HUANG, Xujia HE, Qing WANG, Jianzhuang XIAO

Frontiers of Structural and Civil Engineering 2019, Volume 13, Issue 5,   Pages 1183-1199 doi: 10.1007/s11709-019-0545-3

Abstract: The study on the deformation distribution and crack propagation of concrete under axial compression was conducted by the digital image correlation (DIC) method. The main parameter in this test is the water-cement ( / ) ratio. The novel analysis process and numerical program for DIC method were established. The displacements and strains of coarse aggregate, and cement mortar and interface transition zone (ITZ) were obtained and verified by experimental results. It was found that the axial displacement distributed non-uniformly during the loading stage, and the axial displacements of ITZs and cement mortar were larger than that of coarse aggregates before the occurrence of macro-cracks. The effect of / on the horizontal displacement was not obvious. Test results also showed that the transverse and shear deformation concentration areas (DCAs) were formed when stress reached 30%–40% of the peak stress. The transverse and shear DCAs crossed the cement mortar, and ITZs and coarse aggregates. However, the axial DCA mainly surrounded the coarse aggregate. Generally, the higher / was, the more size and number of DCAs were. The crack propagations of specimens varied with the variation of / . The micro-crack of concrete mainly initiated in the ITZs, irrespective of the / . The number and distribution range of cracks in concrete with high / were larger than those of cracks in specimen adopting low / . However, the value and width of cracks in high / specimen were relatively small. The / had an obvious effect on the characteristics of concrete deterioration. Finally, the characteristics of crack was also evaluated by comparing the calculated results.

Keywords: deformation filed distribution     crack development     digital image correlation method     mechanical properties     water-cement ratio     characteristics of deformation and crack    

Dynamic analyses of steel-reinforced super high-strength concrete columns

JIA Jinqing, JIANG Rui, XU Shilang, HOU Tong

Frontiers of Structural and Civil Engineering 2007, Volume 1, Issue 2,   Pages 240-246 doi: 10.1007/s11709-007-0030-2

Abstract: The dynamic behaviors of steel-reinforced super high-strength concrete columns under seismic loading were studied with a series of experiments. Thirteen specimens, with concrete strengths ranging from 94.9 to 105.4 MPa and shear-span ratios of 2.75, were manufactured. The axial load ratio and the stirrup reinforcement ratio were the main experimental variables affecting the dynamic behavior of the specimens. The columns under low cyclic lateral loading mainly failed in the flexural-shear mode. Shear force-displacement hysteretic curves and skeleton curves were drawn. The coefficients of the specimens displacement ductility were calculated. Experimental results indicate that ductility decreases while the axial load ratio increases, but it increases when the stirrup reinforcement ratio increases. The limit values of the axial load ratio and the minimum stirrup reinforcement ratio of the columns were investigated to satisfy definite ductility requirements. These values were suggested as references of engineering applications and of the amendment of the current Chinese design code of steel reinforced concrete composite structures.

Keywords: amendment     flexural-shear     force-displacement hysteretic     definite ductility     skeleton    

Displacement and force analyses of piles in the pile-caisson composite structure under eccentric inclined

Frontiers of Structural and Civil Engineering doi: 10.1007/s11709-023-0957-y

Abstract: The numerical analyses indicated that the influence of the groundwater level on the stability of the

Keywords: composite structure     piles     foundation     suspension bridge     1g model test     finite-element analysis    

properties of steel- and polypropylene-reinforced ultra-high-performance concrete through numerical analyses

Frontiers of Structural and Civil Engineering   Pages 1228-1248 doi: 10.1007/s11709-023-0931-8

Abstract: Numerical analyses were also carried out using finite element software to account for the sensitivityFurthermore, nonlinear regression analyses were conducted to obtain the flexural load-deflection curvesIn addition, the regression analyses showed excellent consistency with the experimental results, with

Keywords: UHPC     MT-DIC     flexural behavior     tensile behavior     steel fiber     polypropylene fiber    

Application of MoS in the space environment: a review

Frontiers of Mechanical Engineering 2023, Volume 18, Issue 3, doi: 10.1007/s11465-023-0755-1

Abstract: Improving the friction properties of contact surfaces in the space environment is an important way toTraditional lubricants can no longer meet the lubrication requirements of the space environment.This study describes the characteristics of the space environment and the applications of solid lubricantsAdvances in research on the friction properties of collision sliding contacts in the space environment

Keywords: MoS2     soft metal     space environment     surface texture     synergistic effect     vibration    

Title Author Date Type Operation

Macrozoobenthic assemblages in relation to environments of the Yangtze-isolated lakes

Baozhu PAN, Haijun WANG, Hongzhu WANG, Zhaoyin WANG

Journal Article

Strain localization analyses of idealized sands in biaxial tests by distinct element method

Mingjing JIANG, Hehua ZHU, Xiumei LI,

Journal Article

Exergy and exergoeconomic analyses for integration of aromatics separation with aromatics upgrading

Journal Article

Numerical and experimental analyses of methane leakage in shield tunnel

Journal Article

Cohesive zone model-based analyses of localized leakage of segmentally lined tunnels

Journal Article

Iterative finite element model of nonlinear viscoplastic analyses for blended granular porous media

WU Yuching, ZHU Cimian

Journal Article

Image analyses for video-based remote structure vibration monitoring system

Yang YANG,Xiong (Bill) YU

Journal Article

A review of recent experimental investigations and theoretical analyses for pulsating heat pipes

Xin TANG, Lili SHA, Hua ZHANG, Yonglin JU

Journal Article

Design and analyses of open-ended pipe piles in cohesionless soils

Yuan GUO,Xiong (Bill) YU

Journal Article

Fatigue stress monitoring and analyses for steel box girder of Runyang Suspension Bridge

WANG Ying, LI Zhaoxia, WU Baijian

Journal Article

Deformation field and crack analyses of concrete using digital image correlation method

Yijie HUANG, Xujia HE, Qing WANG, Jianzhuang XIAO

Journal Article

Dynamic analyses of steel-reinforced super high-strength concrete columns

JIA Jinqing, JIANG Rui, XU Shilang, HOU Tong

Journal Article

Displacement and force analyses of piles in the pile-caisson composite structure under eccentric inclined

Journal Article

properties of steel- and polypropylene-reinforced ultra-high-performance concrete through numerical analyses

Journal Article

Application of MoS in the space environment: a review

Journal Article