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Numerical simulation of multi-body floating piers to investigate pontoon stability

Mostafa Shahrabi, Khosrow Bargi

《结构与土木工程前沿（英文）》 2013年 第7卷 第3期   页码 325-331 doi: 10.1007/s11709-013-0209-7

摘要： The objective of this study is to develop a procedure to analyze the motions of a floating pier comprised of several pontoons that are modeled as rigid bodies and connected to each other by flexible and rigid connectors. Recently, the use offloating piers has increased because of their advantages, such as faster and higher-quality construction, seismic force isolation for a full-scale mooring system, low dependence on local soil conditions and tides, ability to relocate or reconfigure the pier modules during the operation period and 75-100 years of repair-free service. A floating pier consists of a pier, access bridge, mooring system and fender system, each of which comes in many variations to suit different usages and construction considerations. The typical loads used in the design of these piers are dead loads, live loads, mooring loads, fender loads and environmental loads induced by wind, currents and waves. For numerical simulation, three types of piers are used: passenger piers, light-cargo piers and semi-heavy-cargo piers. The selected piers consist of several large pontoons joined by pivots and have a pile-based mooring system. These piers are modeled by SAP2000software as two-dimensional frames that are linked together. As the first step, each type of pier is subjected to loading, and its general behavior is assessed. According to this behavior, the major load combinations are described for the design of piers and analyzed to determine the behavior of the modules. Lastly, according to the analysis results and the safe use and stability considerations, such as the maximum draft and longitudinal gradient, the dimensions of each module in each pier type are presented.

关键词： coastal structures     numerical simulation     floating pier     rigid pontoons     stability    

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Laboratory experiment on using non-floating body to generate electrical energy from water waves

Arunachalam AMARKARTHIK, Srinivasan CHANDRASEKARAN, Karuppan SIVAKUMAR, Harender SINHMAR

《能源前沿（英文）》 2012年 第6卷 第4期   页码 361-365 doi: 10.1007/s11708-012-0210-1

摘要： This paper describes an innovative method of using a non-buoyant body to harness ocean waves. All the point absorbers are buoyant in nature and move up due to buoyancy and come down because of gravity. The point absorbers are designed to move along the waves to make the device efficient. These devices face excessive stress during the rough weather on account of the extreme motion of waves and cause the total device failure. The present study shows that using a non-buoyant body for conventional point absorber principle is much efficient and safer than any other device proposed till today. A small scale wave energy converter with non-buoyant body was designed, fabricated and tested in small scale wave maker. An electrical generator was coupled with the device to generate electrical energy from harnessed waves. The generator was electrically loaded and the generated power was measured. It was found from the experiments that the proposed device showed a significant improvement in electricity generation and safety during extreme conditions. In addition to the electricity generation, the characteristics of the device were also studied by using various wave and device parameters.

关键词： ocean wave energy     point absorbers     heaving body     non-floating object     heave response ratio     electrical energy generation    

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Study of the mechanics of progressive collapse of FPB isolated beam-pier substructures

Jingcai ZHANG; Yong DING; Xinchun GUAN

《结构与土木工程前沿（英文）》 2022年 第16卷 第6期   页码 718-728 doi: 10.1007/s11709-022-0815-3

摘要： The horizontal stiffness of the isolated layer is reduced substantially by a friction pendulum bearing (FPB) toprotectthe structure from potential damages caused by earthquakes. However, horizontal stiffness is essential to progressive collapse resistance of structures. This paper presents a simplified model to assess the progressive collapse response of beam-pier substructure isolated by FPB. Progressive collapse resistance by flexural action of the beam and additional resistance owing to the horizontal restraining force was achieved. The influences of the equivalent radius and friction coefficient of the FPB, the applied axial force on the FPB, and span-depth ratio of the beam on the additional resistance were investigated. Simulations were conducted to verify the proposed model. The results show that progressive collapse resistance provided by horizontal restraining can be reduced as large as 46% and 88% during compressive arching action (CAA) and catenary action (CA), respectively. The equivalent radius of the FPB shows limited effect on the progressive collapse response of FPB isolated structures, but friction coefficient and applied axial force, as well as depth ratio of the beam, show significant influences on the additional progressive collapse resistance capacity. Finite element method (FEM) results are in good agreement with the result obtained by the proposed method.

关键词： friction pendulum bearing     progressive collapse     horizontal stiffness     compressive arching action     catenary action    

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Dynamic performance of submerged floating tunnel with different mooring styles subjected to anchor cable

《结构与土木工程前沿（英文）》 doi: 10.1007/s11709-023-0932-7

摘要： Submerged floating tunnels (SFTs) are novel structures for transportation across long- and deep-strait regions. Owing to severe wave and current excitation as well as the effects of underwater structures and corrosion, the risk of local anchor cable failure is high, which can result in the progressive failure of the entire structure. In this study, experimental and numerical investigations are conducted to analyze the dynamic behavior of an SFT with different mooring styles under local cable failure. A custom-designed cable failure device and the birth-and-death element method are used to simulate cable failure (i.e., progressive failure) via experiments and numerical simulation, respectively. A physical-scale segmental model of an SFT with different mooring styles under anchor cable failure is developed in this study. A segmental and entire-length mathematical model is developed using the ANSYS program to perform the numerical simulation. The results of the segmental numerical and experimental models indicate good agreement. The dynamic response of an SFT with different mooring styles under cable failure is comprehensively investigated by investigating the effects of key parameters (wave period, buoyant weight ratio, and cable failure mechanism). Moreover, the progressive failure of the SFT under cable failure is investigated via a segment model test and a numerical simulation of its entire length. The present study can serve as a reference for the safer designs of the SFT mooring style.

关键词： dynamic behaviors     submerged floating tunnel     cable failure     mooring style     progressive failure    

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Construction technology on pile foundation of No. 6 main pier in Dashengguan Yangtze Bridge

Hongbin YU , Zeping LIAN ,

《结构与土木工程前沿（英文）》 2009年 第3卷 第3期   页码 339-343 doi: 10.1007/s11709-009-0047-9

摘要： Based on pile foundation construction of No. 6 main pier, deep mudstone geological foundation and deep-water construction in Nanjing-Dashengguan Yangtze Bridge, the method of super-large-diameter bored pile in deep water is studied. The spread drill, application of PHP mud, and choice of machine are solved by adopting two machines of KTY4000 and KPG300A. Besides, the airlift reversing circulation is selected in slag discharge. The results show that this method can ensure successfully the construction of pier foundation to satisfy the demands of codes.

关键词： PHP slurry     KTY4000 drilling machine     KPG3000A drilling machine     spread drill    

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A method for predicting consolidation settlements of floating column improved clayey subsoil

Jinchun CHAI, Supasit PONGSIVASATHIT,

《结构与土木工程前沿（英文）》 2010年 第4卷 第2期   页码 241-251 doi: 10.1007/s11709-010-0024-3

摘要： A method of predicting the consolidation settlement-time curve of floating soil-cement column on improved soft clayey subsoil has been proposed. The degree of the consolidation (()) of the system is calculated by the double soil-layer consolidation theory, and the methods for evaluating the equivalent hydraulic conductivity () and the coefficient of volume compressibility () of the part of the column improved layer have been proposed. The effectiveness of the method was verified by comparing predictions with the results of finite element analysis (FEA) using a unit cell model. The consolidation settlement (()) can be calculated by the method of treating a part of the column improved layer as an unimproved layer and using the corresponding average () value. By comparing the predicted results with the measurements of laboratory model tests and three case histories in Fukuoka, Japan, the effectiveness of the proposed methods has been verified. It is suggested that the method can be used for designing the soft clayey subsoil improvement using floating soil-cement columns.

关键词： cement depth mixing     ground improvement     consolidation     settlement    

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Highly efficient and selective removal of vanadium from tungstate solutions by microbubble floating-extraction

《化学科学与工程前沿（英文）》 2023年 第17卷 第5期   页码 581-593 doi: 10.1007/s11705-022-2235-2

摘要： Selective separation of dissolved tungsten and vanadium is of great significance for the utilization of the secondary resources of these elements. In this work, selective removal of vanadium from tungstate solutions via microbubble floating-extraction was systematically investigated. The results indicated that vanadium can be more easily mineralized over tungsten from tungstate solutions using methyl trioctyl ammonium chloride as mineralization reagent under weak alkaline conditions. Owing to the higher bubble and interface mass transfer rates, high-efficiency enrichment and deep separation of vanadium could be achieved easily. Additionally, the deep recovery of tungsten and vanadium from the floated organic phase could be easily realized using a mixed solution of sodium hydroxide and sodium chloride as stripping agents. The separation mechanism mainly included the formation of hydrophobic complexes, their attachment on the surface of rising bubbles, and their mass transfer at the oil–water interface. Under the optimal conditions, the removal efficiency of vanadium reached 98.5% with tungsten loss below 8% after two-stage microbubble floating-extraction. Therefore, the microbubble floating-extraction could be an efficient approach for separating selectively vanadium from tungstate solutions, exhibiting outstanding advantages of high separation efficiency and low consumption of organic solvents.

关键词： tungsten     vanadium     selective separation     reagent mineralization     microbubble floating-extraction    

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Role of biologic components in a novel floating-bed combining

Hailiang SONG, Xianning LI, Wei LI, Xiwu LU

《环境科学与工程前沿（英文）》 2014年 第8卷 第2期   页码 215-225 doi: 10.1007/s11783-013-0587-z

摘要： A novel floating-bed incorporated with water spinach ( ), Asiatic clam ( ), and carrier media supported biofilm was developed for eutrophic water purification. The contributions of each biologic component to the removals of total nitrogen (TN), total phosphorus (TP) and Chl.a were examined. The nutrient removals due to the direct uptake by either water spinach or Asiatic clam were less than 10%, suggesting a negligible role of biologic assimilation and leaving the biofilm as the indispensable biologic component in the floating-bed. Chl.a was reduced mainly by Asiatic clams via filter-feeding. Meanwhile, the digestion and excretion of Asiatic clams benefited the proliferation of nitrifying and denitrifying bacteria, resulting in the improvement of TN removal. In summary, the synergetic effects of water spinach, Asiatic clams and biofilms would promote the eutrophic water treatment performance of floating-bed in comparison with the conventional floating-bed with vegetation as the single biologic component.

关键词： floating-bed     Corbicula fluminea     biofilm carrier     eutrophication    

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Resistance of large caisson in floating transport considering the influence of air

Junjie ZHENG, Zongzhe LI, Dongan ZHAO, Qiang MA, Rongjun ZHANG,

《结构与土木工程前沿（英文）》 2010年 第4卷 第3期   页码 331-338 doi: 10.1007/s11709-010-0085-3

摘要： This paper deals with the floating resistance of super large caisson by numerical simulation, and the influence of air resistance on the caisson, which is often ignored by previous researchers, is considered. The floating caisson of Taizhou Highway Bridge’s middle tower pier is investigated, and the software package FLUENT is used to simulate the floating process of large-scale rounded rectangular steel caisson. This simulation adopts the volume of fluid (VOF) model with water-air two-phase flow, which can take both the hydraulic resistance and air resistance into account. Subsequently, the analyses on hydraulic resistance and air resistance under different working conditions, such as different flow velocities and different draughts of water are performed, and the results are compared with those calculated by related empirical formula. The comparison shows that the air resistance takes up notable portion in the total resistance on the floating caisson, and the effect of air resistance on the safety of caisson should be paid sufficient attention to rather than be ignored.

关键词： large-scale caisson     numerical simulation     hydraulic resistance     air resistance    

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High-precision gyro-stabilized control of a gear-driven platform with a floating gear tension device

《机械工程前沿（英文）》 2021年 第16卷 第3期   页码 487-503 doi: 10.1007/s11465-021-0635-5

摘要： This study presents an improved compound control algorithm that substantially enhances the anti-disturbance performance of a gear-drive gyro-stabilized platform with a floating gear tension device. The tension device can provide a self-adjustable preload to eliminate the gap in the meshing process. However, the weaker gear support stiffness and more complex meshing friction are also induced by the tension device, which deteriorates the control accuracy and the ability to keep the aim point of the optical sensors isolated from the platform motion. The modeling and compensation of the induced complex nonlinearities are technically challenging, especially when base motion exists. The aim of this research is to cope with the unmeasured disturbances as well as the uncertainties caused by the base lateral motion. First, the structural properties of the gear transmission and the friction-generating mechanism are analyzed, which classify the disturbances into two categories: Time-invariant and time-varying parts. Then, a proportional-integral controller is designed to eliminate the steady-state error caused by the time-invariant disturbance. A proportional multiple-integral-based state augmented Kalman filter is proposed to estimate and compensate for the time-varying disturbance that can be approximated as a polynomial function. The effectiveness of the proposed compound algorithm is demonstrated by comparative experiments on a gear-drive pointing system with a floating gear tension device, which shows a maximum 76% improvement in stabilization precision.

关键词： inertially stabilized platform     floating gear tension device     nonlinear friction     disturbance compensation     proportional multiple-integral observer    

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Trajectory planning and base attitude restoration of dual-arm free-floating space robot by enhanced bidirectional

Zongwu XIE1 , Xiaoyu ZHAO1 , Zainan JIANG1 , Haitao YANG2 , Chongyang LI1

《机械工程前沿（英文）》 2022年 第17卷 第1期 doi: 10.1007/s11465-021-0658-y

摘要： When free-floating space robots perform space tasks, the satellite base attitude is disturbed by the dynamic coupling. The disturbance of the base orientation may affect the communication between the space robot and the control center on earth. In this paper, the enhanced bidirectional approach is proposed to plan the manipulator trajectory and eliminate the final base attitude variation. A novel acceleration level state equation for the nonholonomic problem is proposed, and a new intermediate variable-based Lyapunov function is derived and solved for smooth joint trajectory and restorable base trajectories. In the method, the state equation is first proposed for dual-arm robots with and without end constraints, and the system stability is analyzed to obtain the system input. The input modification further increases the system stability and simplifies the calculation complexity. Simulations are carried out in the end, and the proposed method is validated in minimizing final base attitude change and trajectory smoothness. Moreover, the minute internal force during the coordinated operation and the considerable computing efficiency increases the feasibility of the method during space tasks.

关键词： free-floating space robot     dual arm     coordinated operation     base attitude restoration     bidirectional approach    

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Floating forest: A novel breakwater-windbreak structure against wind and wave hazards

《结构与土木工程前沿（英文）》 2021年 第15卷 第5期   页码 1111-1127 doi: 10.1007/s11709-021-0757-1

摘要： A novel floating breakwater-windbreak structure (floating forest) has been designed for the protection of vulnerable coastal areas from extreme wind and wave loadings during storm conditions. The modular arch-shaped concrete structure is positioned perpendicularly to the direction of the prevailing wave and wind. The structure below the water surface acts as a porous breakwater with wave scattering capability. An array of tubular columns on the sloping deck of the breakwater act as an artificial forest-type windbreak. A feasibility study involving hydrodynamic and aerodynamic analyses has been performed, focusing on its capability in reducing wave heights and wind speeds in the lee side. The study shows that the proposed 1 km long floating forest is able to shelter a lee area that stretches up to 600 m, with 40%–60% wave energy reduction and 10%–80% peak wind speed reduction.

关键词： floating structure     breakwater     windbreak     hydrodynamic     CFD    

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闸墩混凝土结构温控防裂措施智能优选研究

黄耀英,丁月梅,吕晓曼,徐佰林

《中国工程科学》 2014年 第16卷 第3期   页码 59-63

摘要：

闸墩混凝土温控防裂是一个与温控措施和材料参数相关的复杂多因素系统优选问题，本文尝试已知混凝土热力学材料参数情况下的温控措施优选，将闸墩混凝土结构内部和表面主拉应力历时曲线和抗拉强度增长曲线关系的最小值作为输入，闸墩表面保温效果、浇筑温度、通水水温、通水时间作为输出，建立了温控措施优选的神经网络模型，采用均匀设计原理进行温控参数组合，并采用水管冷却有限元法仿真分析含冷却水管的闸墩混凝土结构温度场和徐变应力场，获得样本进行学习，以此训练好的网络描述结构主拉应力历时曲线和抗拉强度增长曲线关系的最小值与不同温控措施的非线性关系。将合适的结构主拉应力历时曲线和抗拉强度增长曲线关系的最小值输入训练好的网络，可自动优选出温控防裂措施。算例分析表明，本文建立的温控措施优选神经网络模型是可行的。

关键词： 闸墩     表面保温     通水冷却     浇筑温度     智能优选    

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Ultrasound-assisted emulsification solidified floating organic drop microextraction for the determination

Qingyun CHANG, Jingwen ZHANG, Xin DU, Jingjun MA, Jingci LI,

《环境科学与工程前沿（英文）》 2010年 第4卷 第2期   页码 187-195 doi: 10.1007/s11783-010-0030-7

摘要： A simple and efficient liquid-phase microextraction (LPME) technique was developed using ultrasound-assisted emulsification solidified floating organic drop microextraction (USAE-SFODME) combined with flame atomic absorption spectrometry, for the extraction and determination of trace copper in water samples. 1-(2-Pyridylazo)-2-naphthol (PAN) was used as chelating agent. Microextraction efficiency factors (including extraction solvent type, extraction volume, time, temperature, and pH), the amount of the chelating agent, and salt effect were investigated and optimized. Under the optimum extraction conditions, figures of merit of the proposed method were evaluated. The calibration graph was linear in the range of 20–600 g·L with a detection limit of 0.76 g·L. The relative standard deviation (R.S.D) for ten replicate measurements of 20 and 400 g·L of copper was 3.83% and 2.65%, respectively. Finally, the proposed method was applied to tap water, river water, and sea water, and accuracy was assessed through the analysis of certified reference water or recovery experiments.

关键词： ultrasound-assisted emulsification     solidified floating organic drop microextraction     flame atomic absorption spectrometry     preconcentration     copper    

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Enhanced nitrification in integrated floating fixed-film activated sludge (IFFAS) system using novel

Aoshuang Jing, Tao Liu, Xie Quan, Shuo Chen, Yaobin Zhang

《环境科学与工程前沿（英文）》 2019年 第13卷 第5期 doi: 10.1007/s11783-019-1153-0

摘要： Novel carriers with favorable electrophilicity and hydrophilicity were prepared. Novel carriers had the capability of nitrification-enhancing. NH4+-N removal efficiency of IFFAS process rose up to 20% with novel carriers. Nitrosomonadales and Nitrospirales were identified as the functional nitrifiers. The population of Nitrospirales increased by 4.51%. The integrated floating fixed-film activated sludge (IFFAS) process is an ideal preference for nitrification attributing to the longer sludge age for nitrifiers. However, as the core of this process, conventional carriers made of polymer materials usually exhibit negative charge and hydrophobicity on the surface, which is unbeneficial to nitrifying biofilm formation. In this study, novel clinoptilolite composite carriers with favorable hydrophilicity, positive charge and nitrification-enhancing capability were made and implemented in IFFAS system. In comparison with conventional carriers, the novel clinoptilolite composite carriers displayed positive charges on the surface (11.7±1.1 mV, pH 7.0) with increased hydrophilicity (surface contact angle dropped to 76.7°). The novel-carriers-based reactors achieved significantly better NH4+-N removal efficiency at different influent concentrations, dissolved oxygen (DO) levels and shock loads (NH4+-N removal efficiency rose up to 20% comparing with the control reactors filled with polyethylene (PE) carriers or activated sludge). High-throughput sequencing (HTS) results indicated the novel clinoptilolite composite carriers provided favorable niche for more types of bacteria, especially for Nitrosomonadales and Nitrospirales (the functional nitrifiers in the system). The population of Nitrospirales increased by 4.51% by using novel clinoptilolite composite carriers comparing with using PE carriers, which ensured enhanced nitrification process. This study was expected to provide a practical option for enhancing wastewater nitrification performance with the novel clinoptilolite composite carrier.

关键词： Biofilm carrier     Clinoptilolite     Integrated floating fixed-film activated sludge (IFFAS)     Microbial community     Nitrification     Wastewater    

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标题 作者 时间 类型 操作

Numerical simulation of multi-body floating piers to investigate pontoon stability

Mostafa Shahrabi, Khosrow Bargi

期刊论文

Laboratory experiment on using non-floating body to generate electrical energy from water waves

Arunachalam AMARKARTHIK, Srinivasan CHANDRASEKARAN, Karuppan SIVAKUMAR, Harender SINHMAR

期刊论文

Study of the mechanics of progressive collapse of FPB isolated beam-pier substructures

Jingcai ZHANG; Yong DING; Xinchun GUAN

期刊论文

Dynamic performance of submerged floating tunnel with different mooring styles subjected to anchor cable

期刊论文

Construction technology on pile foundation of No. 6 main pier in Dashengguan Yangtze Bridge

Hongbin YU , Zeping LIAN ,

期刊论文

A method for predicting consolidation settlements of floating column improved clayey subsoil

Jinchun CHAI, Supasit PONGSIVASATHIT,

期刊论文

Highly efficient and selective removal of vanadium from tungstate solutions by microbubble floating-extraction

期刊论文

Role of biologic components in a novel floating-bed combining

Hailiang SONG, Xianning LI, Wei LI, Xiwu LU

期刊论文

Resistance of large caisson in floating transport considering the influence of air

Junjie ZHENG, Zongzhe LI, Dongan ZHAO, Qiang MA, Rongjun ZHANG,

期刊论文

High-precision gyro-stabilized control of a gear-driven platform with a floating gear tension device

期刊论文

Trajectory planning and base attitude restoration of dual-arm free-floating space robot by enhanced bidirectional

Zongwu XIE1 , Xiaoyu ZHAO1 , Zainan JIANG1 , Haitao YANG2 , Chongyang LI1

期刊论文

Floating forest: A novel breakwater-windbreak structure against wind and wave hazards

期刊论文

闸墩混凝土结构温控防裂措施智能优选研究

黄耀英,丁月梅,吕晓曼,徐佰林

期刊论文

Ultrasound-assisted emulsification solidified floating organic drop microextraction for the determination

Qingyun CHANG, Jingwen ZHANG, Xin DU, Jingjun MA, Jingci LI,

期刊论文

Enhanced nitrification in integrated floating fixed-film activated sludge (IFFAS) system using novel

Aoshuang Jing, Tao Liu, Xie Quan, Shuo Chen, Yaobin Zhang

期刊论文