The precise control of the shape of transversely stiffened suspended cable systems is crucial. However, existing form-finding methods primarily rely on iterative calculations that treat loads as fixed known conditions...The precise control of the shape of transversely stiffened suspended cable systems is crucial. However, existing form-finding methods primarily rely on iterative calculations that treat loads as fixed known conditions. These methods are inefficient and fail to accurately control shape results. In this study, we propose a form-finding method that analyzes the load response of models under different sag and stress levels, taking into account the construction process. To analyze the system, a structural finite element model was established in ANSYS, and geometric nonlinear analysis was conducted using the Newton-Raphson method. The form-finding analysis results demonstrate that the proposed method achieves precise control of shape, with a maximum shape error ranging from 0.33% to 0.98%. Furthermore, the relationships between loads and tension forces are influenced by the deformed shape of the structures, exhibiting significant geometric nonlinear characteristics. Meanwhile, the load response analysis reveals that the stress level of the self-equilibrium state in the transversely stiffened suspended cable system is primarily governed by strength criteria, while shape is predominantly controlled by stiffness criteria. Importantly, by simulating the initial tensioning process as an initial condition, this method solves for a counterweight that satisfies the requirements and achieves a self-equilibrium state with the desired shape. The shape of the self-equilibrium state is precisely controlled by simulating the construction process. Overall, this work presents a new method for analyzing the form-finding process of large-span transversely stiffened suspended cable system, considering the construction process which was often overlooked in previous studies.展开更多
The comprehension of sediment grain size parameters and the corresponding sedimentary environment holds paramount importance in elucidating the engineering geological attributes of the subaqueous seabed.This study del...The comprehension of sediment grain size parameters and the corresponding sedimentary environment holds paramount importance in elucidating the engineering geological attributes of the subaqueous seabed.This study delineated the sedimentary environment zoning in the northern sea area of Qingdao through cluster analysis of grain size parameters derived from 123 surface sediment samples.The study analyzed the correlation between sediment geotechnical indices and grain size parameters across diverse sedimentary environments.A correlation equation was established for samples exhibiting a strong correlation.The study found four distinct sedimentary environments in the study area:coastal,transitional,shallow sea,and residual.Within the same sedimentary environment,the average grain size and sorting coefficient exhibit significant correlations with geotechnical indices such as water content,density,shear strength,plastic limit,liquid limit,and plastic index.However,notable disparities in the correlation between grain size parameters and geotechnical indices emerge across different sedimentary environments.展开更多
This paper focuses on the performance of a braced deep excavation in soft soil based on field monitoring and numerical modeling.Laboratory tests were conducted to determine the soil parameters used in the modified Cam...This paper focuses on the performance of a braced deep excavation in soft soil based on field monitoring and numerical modeling.Laboratory tests were conducted to determine the soil parameters used in the modified Cam–Clay(MCC)model.Intelligent field monitoring means were adopted and a three-dimensional model was established.Spatial and temporal effects induced by the excavation are investigated for the deep-large foundation pit in soft soil.Deformation characteristics of the enclosure structure and the surrounding environment throughout the excavation process are presented.The behaviors of diaphragm walls,columns,the maximum wall deflection rate,ground surface settlement,and utility pipelines were focused on and investigated during the whole excavation process.Besides,the axial forces of the internal supports are analyzed.Based on the measured and simulated data,the following main conclusions were obtained:the numerical simulation results are in good agreement with the measured values,which proves the accuracy of the model parameters;the wall and the ground surface showed the maximum displacement increment at stage 9,which was a coupled product of the"creep effect"of the soft soil in Nanjing,China and the"depth effect"of the excavation;as the excavation progressed,the ground settlement changed from a"rising"to a"spoon-shaped"trend,dvm was measured betweenδ_(vm)=0.0686%H andδ_(vm)=0.1488%H;the rebound deformation curve of the pit bottom was corrugated,and the depth of disturbance of the pit bottom after the completion of soil unloading was 2–3 times the excavation depth;the closer the pipeline is to the corner of the pit,the less the excavation process will affect the settlement of the pipeline and the less the obvious pit corner effect will occur;the support strength of the buttress and the longest corner brace should be strengthened during the actual construction process to ensure the stability of the foundation deformation.展开更多
Purpose–This study purposes to study the influence of artificial freezing on the liquefaction characteristics of Nanjing sand,as well as its mechanism.Design/methodology/approach–was studied through dynamic triaxial...Purpose–This study purposes to study the influence of artificial freezing on the liquefaction characteristics of Nanjing sand,as well as its mechanism.Design/methodology/approach–was studied through dynamic triaxial tests by means of the GDS dynamic triaxial system on Nanjing sand extensively discovered in the middle and lower reaches of the Yangtze River under seismic load and metro train vibration load,respectively,and potential hazards of the two loads to the freezing construction of Nanjing sand were also identified in the tests.Findings–The results show that under both seismic load and metro train vibration load,freeze-thaw cycles will significantly reduce the stiffness and liquefaction resistance of Nanjing sand,especially in the first freezethaw cycle;the more freeze-thaw cycles,the worse structural behaviors of silty-fine sand,and the easier to liquefy;freeze-thaw cycles will increase the sensitivity of Nanjing sand’s dynamic pore pressure to dynamic load response;the lower the freezing temperature and the effective confining pressure,the worse the liquefaction resistance of Nanjing sand after freeze-thaw cycles;compared to the metro train vibration load,the seismic load in Nanjing is potentially less dangerous to freezing construction of Nanjing sand.Originality/value–The research results are helpful to the construction of the artificial ground freezing of the subway crossing passage in the lower reaches of the Yangtze River and to ensure the construction safety of the subway tunnel and its crossing passage.展开更多
In recent years,China has witnessed the rapid development in housing finance,and there have emerged constantly real estate finance innovations;however,there exists no relevant index for measuring the innovations of Ch...In recent years,China has witnessed the rapid development in housing finance,and there have emerged constantly real estate finance innovations;however,there exists no relevant index for measuring the innovations of China's real estate finance.Based on the perspectives of the governments,enterprises and the public,this paper constructs the"innovation index of real estate finance"on a quarterly basis from 2009 to 2019,with the method of empowerment which combines the subjective method(analytic hierarchy process)and the objective one(range coefficient method).It clearly and concretely depicts the innovations in housing finance and the related temporal-spatial characteristics in China since the outbreak of the financial crisis in 2008.The index covers 30 provinces,autonomous regions and municipalities directly under the central government,and analyzes its temporal and spatial characteristics.The findings show that there exist a strong spatial autocorrelation and a big regional difference in innovations.展开更多
A European pressurized reactor (EPR) steel containment liner structure is comprised of the cylinder part and the dome part. An introduction of the steel liner structure is presented, followed by studies on the key m...A European pressurized reactor (EPR) steel containment liner structure is comprised of the cylinder part and the dome part. An introduction of the steel liner structure is presented, followed by studies on the key mechanical features of the construction process using a refined finite element method. The steel liner was divided into several modules and then assembled during construction. Firstly, the equipment structure used to hoist the liner module was optimized, the lifting lug was analyzed using a multi-scale finite element model; the wind speed limit during lifting was also studied. Subsequently, the effect of internal forces during assembly between the liner modules, the lateral pressure of fresh concrete, the non-uniform temperature load, and the wind load on the cylinder module was analyzed. According to the time-varying structural performance during continuous concrete pouring and the hardening construction, an "overlapping element and birth-death element" technique was adopted to analyze the deformation and stress of the long-span steel dome liner. In addition, the stability-bearing capacities of the dome structure during construction were also studied, which took into consideration the effect of the initial geometrical imperfections and the elasto-plasticity of the material. This study presents a reference in terms of the mechanics of the construction scheme and the safety of such a type of structure.展开更多
文摘The precise control of the shape of transversely stiffened suspended cable systems is crucial. However, existing form-finding methods primarily rely on iterative calculations that treat loads as fixed known conditions. These methods are inefficient and fail to accurately control shape results. In this study, we propose a form-finding method that analyzes the load response of models under different sag and stress levels, taking into account the construction process. To analyze the system, a structural finite element model was established in ANSYS, and geometric nonlinear analysis was conducted using the Newton-Raphson method. The form-finding analysis results demonstrate that the proposed method achieves precise control of shape, with a maximum shape error ranging from 0.33% to 0.98%. Furthermore, the relationships between loads and tension forces are influenced by the deformed shape of the structures, exhibiting significant geometric nonlinear characteristics. Meanwhile, the load response analysis reveals that the stress level of the self-equilibrium state in the transversely stiffened suspended cable system is primarily governed by strength criteria, while shape is predominantly controlled by stiffness criteria. Importantly, by simulating the initial tensioning process as an initial condition, this method solves for a counterweight that satisfies the requirements and achieves a self-equilibrium state with the desired shape. The shape of the self-equilibrium state is precisely controlled by simulating the construction process. Overall, this work presents a new method for analyzing the form-finding process of large-span transversely stiffened suspended cable system, considering the construction process which was often overlooked in previous studies.
基金funded by the National Key R&D Program Project(No.2022YFC3103604).
文摘The comprehension of sediment grain size parameters and the corresponding sedimentary environment holds paramount importance in elucidating the engineering geological attributes of the subaqueous seabed.This study delineated the sedimentary environment zoning in the northern sea area of Qingdao through cluster analysis of grain size parameters derived from 123 surface sediment samples.The study analyzed the correlation between sediment geotechnical indices and grain size parameters across diverse sedimentary environments.A correlation equation was established for samples exhibiting a strong correlation.The study found four distinct sedimentary environments in the study area:coastal,transitional,shallow sea,and residual.Within the same sedimentary environment,the average grain size and sorting coefficient exhibit significant correlations with geotechnical indices such as water content,density,shear strength,plastic limit,liquid limit,and plastic index.However,notable disparities in the correlation between grain size parameters and geotechnical indices emerge across different sedimentary environments.
基金financial support provided by Beijing Natural Science Foundation(Grant No.8222005)the National Natural Science Foundation of China(Grant No.51978018)Science and Technology Funding Scheme for Three Companies of China Construction Bureau Ⅱ(No.CSCEC2b3c-2021-K-65).
文摘This paper focuses on the performance of a braced deep excavation in soft soil based on field monitoring and numerical modeling.Laboratory tests were conducted to determine the soil parameters used in the modified Cam–Clay(MCC)model.Intelligent field monitoring means were adopted and a three-dimensional model was established.Spatial and temporal effects induced by the excavation are investigated for the deep-large foundation pit in soft soil.Deformation characteristics of the enclosure structure and the surrounding environment throughout the excavation process are presented.The behaviors of diaphragm walls,columns,the maximum wall deflection rate,ground surface settlement,and utility pipelines were focused on and investigated during the whole excavation process.Besides,the axial forces of the internal supports are analyzed.Based on the measured and simulated data,the following main conclusions were obtained:the numerical simulation results are in good agreement with the measured values,which proves the accuracy of the model parameters;the wall and the ground surface showed the maximum displacement increment at stage 9,which was a coupled product of the"creep effect"of the soft soil in Nanjing,China and the"depth effect"of the excavation;as the excavation progressed,the ground settlement changed from a"rising"to a"spoon-shaped"trend,dvm was measured betweenδ_(vm)=0.0686%H andδ_(vm)=0.1488%H;the rebound deformation curve of the pit bottom was corrugated,and the depth of disturbance of the pit bottom after the completion of soil unloading was 2–3 times the excavation depth;the closer the pipeline is to the corner of the pit,the less the excavation process will affect the settlement of the pipeline and the less the obvious pit corner effect will occur;the support strength of the buttress and the longest corner brace should be strengthened during the actual construction process to ensure the stability of the foundation deformation.
基金supported by the National Natural Science Foundation of China(Grant No.U41702299).
文摘Purpose–This study purposes to study the influence of artificial freezing on the liquefaction characteristics of Nanjing sand,as well as its mechanism.Design/methodology/approach–was studied through dynamic triaxial tests by means of the GDS dynamic triaxial system on Nanjing sand extensively discovered in the middle and lower reaches of the Yangtze River under seismic load and metro train vibration load,respectively,and potential hazards of the two loads to the freezing construction of Nanjing sand were also identified in the tests.Findings–The results show that under both seismic load and metro train vibration load,freeze-thaw cycles will significantly reduce the stiffness and liquefaction resistance of Nanjing sand,especially in the first freezethaw cycle;the more freeze-thaw cycles,the worse structural behaviors of silty-fine sand,and the easier to liquefy;freeze-thaw cycles will increase the sensitivity of Nanjing sand’s dynamic pore pressure to dynamic load response;the lower the freezing temperature and the effective confining pressure,the worse the liquefaction resistance of Nanjing sand after freeze-thaw cycles;compared to the metro train vibration load,the seismic load in Nanjing is potentially less dangerous to freezing construction of Nanjing sand.Originality/value–The research results are helpful to the construction of the artificial ground freezing of the subway crossing passage in the lower reaches of the Yangtze River and to ensure the construction safety of the subway tunnel and its crossing passage.
基金Supported by the National Science Foundation of China (71850014,71974108)Research on the Scientific and Technological Support Measures to Ensure Financial Security (2020-ZW10-A-022)R&D Program of China Construction Second Engineering Bureau Ltd (2021ZX190001)。
文摘In recent years,China has witnessed the rapid development in housing finance,and there have emerged constantly real estate finance innovations;however,there exists no relevant index for measuring the innovations of China's real estate finance.Based on the perspectives of the governments,enterprises and the public,this paper constructs the"innovation index of real estate finance"on a quarterly basis from 2009 to 2019,with the method of empowerment which combines the subjective method(analytic hierarchy process)and the objective one(range coefficient method).It clearly and concretely depicts the innovations in housing finance and the related temporal-spatial characteristics in China since the outbreak of the financial crisis in 2008.The index covers 30 provinces,autonomous regions and municipalities directly under the central government,and analyzes its temporal and spatial characteristics.The findings show that there exist a strong spatial autocorrelation and a big regional difference in innovations.
基金Project supported by the China State Construction Engineering Corporation Funded Project (No. CSCEC-2008-Z-17), the National Natural Science Foundation of China (No. 51308155), the Funda- mental Research Funds for the Central Universities of China (No. HIT.NSRIF.2014100), and the China Postdoctoral Science Founda- tion Funded Proiect (Nos. 2013M541389 and 2015T80355)
文摘A European pressurized reactor (EPR) steel containment liner structure is comprised of the cylinder part and the dome part. An introduction of the steel liner structure is presented, followed by studies on the key mechanical features of the construction process using a refined finite element method. The steel liner was divided into several modules and then assembled during construction. Firstly, the equipment structure used to hoist the liner module was optimized, the lifting lug was analyzed using a multi-scale finite element model; the wind speed limit during lifting was also studied. Subsequently, the effect of internal forces during assembly between the liner modules, the lateral pressure of fresh concrete, the non-uniform temperature load, and the wind load on the cylinder module was analyzed. According to the time-varying structural performance during continuous concrete pouring and the hardening construction, an "overlapping element and birth-death element" technique was adopted to analyze the deformation and stress of the long-span steel dome liner. In addition, the stability-bearing capacities of the dome structure during construction were also studied, which took into consideration the effect of the initial geometrical imperfections and the elasto-plasticity of the material. This study presents a reference in terms of the mechanics of the construction scheme and the safety of such a type of structure.