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Improvement of sludge dewaterability with modified cinder via affecting EPS

Frontiers of Environmental Science & Engineering 2017年第6期11卷 179-192页

作者： Weichao Ma Lei Zhao Huiling Liu Qianliang Liu Jun Ma State Key Laboratory of Urban Water Resource and Environment Harbin Institute of Technology Harbin 150090 China School of Architectural Engineering Heilongiiang University Harbin 150080 China Key Laboratory of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin 150090 China Key Laboratory of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of Technology Harbin 150090 China

The relationship between the improvement of sludge dewaterability and variation of organic matters has been studied in the process of sludge pre-conditioning with modified cinder, especially for extracellular polymeric substances （EPS） in the sludge. During the conditioning process, the decreases of total organic carbon （TOC） and soluble chemical oxygen demand （SCOD） were obviously in the supernatant especially for the acid modified cinder （ACMC）, which could be attributed to the processes of adsorption and sweeping. The reduction of polysaccharide and protein in supernatant indicated that ACMC might adsorb EPS so that the tightly bound EPS （TB-EPS） decreased in sludge. In the case of ACMC addition with 24 g·L^-1, SRF of the sludge decreased from 7.85 × 10^12 m·kg^-1 to 2.06× 10^12 m·kg^-1, and the filter cake moisture decreased from 85% to 60%. The reconstruction of ＂floc mass＂ was confirmed as the main sludge conditioning mechanism. ACMC promoted the dewatering performance through the charge neutralization and adsorption bridging with the negative EPS, and provided firm and dense structure for sludge floc as skeleton builder. The passages for water quick transmitting were built to avoid collapsing during the high-pressure process.

关键词： Sludge conditioning Acid or alkali modified cinder TB-EPS Floc mass Floc reconstruction

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Flexural behaviour of precast, prestressed ribbed RPC bottom panels

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Open Civil Engineering Journal 2015年第1期9卷 535-543页

作者： Wenzhong, Zheng Xueyuan, Lu Ying, Wang Key Lab of Structures Dynamic Behavior and Control of the Ministry Education Harbin Institute of Technology Harbin150090 China

This study introduces a new type of precast, prestressed reactive powder concrete (RPC) bottom panel for a large-span composite slab. The bottom panels, which have one or two inverted ribs with openings, act as formwork during the construction stage. The paper experimentally investigated the crack characteristics, deflection, and normal section bearing capacity of four precast, prestressed ribbed RPC bottom panels under flexural load. The results indicated that the RPC ultimate strain under non-uniform compression is 5500×10-6and the plastic influence coefficient of the section modulus is linear with the longitudinal reinforcement ratio. The tensile stress of RPC at the cracked section should be considered while calculating the flexural stiffness;the equation used to determine the nominal tensile stress of RPC as a major variable for calculating the crack width at the bottom of panels was proposed. The bottom panels generally exhibit an over-reinforced failure mode behaviour without the composite layer;the calculation method of the normal section bearing capacity of this mode was established. © Wenzhong et al.

关键词： Bearing capacity

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Lattice Modelling of Chloride Diffusivity of Hardened Cement Paste

Lattice Modelling of Chloride Diffusivity of Hardened Cement...

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The 14th International Congress on the Chemistry of Cement（ICCC 2015）

作者： Hongzhi Zhang Xinchun Guan Jinping Ou Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology

Based on numerical micro-structure model of cement paste,a lattice diffusion model is generated to study the influence of randomness on the chloride diffusion coefficient of capillary pore *** results indicate that,compared with regular model,random model has longer diffusion distance,consequently,in order to get same simulation diffusion results,the former's diffusion coefficient should be adjusted a lttlte *** Lattice models have been used in fracture mechanics of cement-based materials for a long ***,the use of lattice models has been extended on simulating chloride transport processes in this *** of the transport models focus on simulation method and process,but the difference of simulated results caused by randomness is generally *** this paper,a lattice diffusion model is generated to study the influence of randomness on the chloride diffusion coefficient of capillary pore element,the reason that different simulation method has different results is also found.

关键词： durability micro-scale lattice model chloride diffusion

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Long-term performance of steel-recycled aggregate concrete continuous composite beams considering the influence of installing decorative layers

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Engineering structures 2025年 339卷

作者： Xuepeng Chen Huan Zhang Yu-Yin Wang Hongzhe Dai Lilong Fan Yue Geng Key Lab of Structures Dynamic Behaviour and Control of the Ministry of Education Harbin Institute of Technology Harbin 150090 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of Technology Harbin 150090 China China Railway Construction Bridge Engineering Bureau Group Co. Ltd. Tianjin 300000 China State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures Nanning Guangxi 530004 China

Steel-recycled aggregate concrete composite beams (SRACCBs) are preferred components for the recycled aggregate concrete (RAC) application. Due to their superior spanning ability and load-bearing capacity, steel-concrete composite beams (SCCBs) are typically more slender than traditional beam components, which makes them more sensitive to concrete shrinkage and creep. Furthermore, the incorporation of recycled aggregate (RA) significantly increases the shrinkage and creep deformation of the concrete. Therefore, the long-term properties of RAC significantly affect the application of SRACCBs. In fact, the shrinkage and creep of RAC are closely related to the boundary conditions, and the sealing effect of the steel deck and decorative layer can directly influence the long-term deformation of SCCBs. However, relevant research is currently unavailable. In this context, a 500-day long-term performance test of continuous SRACCB (4 m × 2 spans) was conducted in this paper. The test quantified the effects of incorporating RA and installing decorative layers on the mid-span deflection and end relative slip of the SRACCBs. By considering the cracking, shrinkage, and creep of RAC and long-term slip at the interface, a Direct Stiffness Method Finite Element Model (DSMFEM) for SRACCBs was established. Test results indicate that using 100 % RA can increase the mid-span deflection of the specimen by 27.9 % and the relative slip by 54.8 %; a 90-day installation of the decoration layer can lead to a 16.3 % decrease in the mid-span deflection and an 11.5 % decrease in the relative slip. The verification results of 12 sets of experimental data indicate that the proposed DSMFEM has high computational efficiency and can effectively predict the deflection and relative slip of simply-supported and continuous SCCBs. The maximum error in predicting the final mid-span deflection is 6.8 % for specimens with long-term loads and 18.4 % for specimens without loads.

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Numerical Analysis on the Effect of Vital Design Parameters on the Seismic Performance of Shear Walls with Horizontal Ring Connection 7

Numerical Analysis on the Effect of Vital Design Parameters ...

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7th International Conference on Environmental Science and Civil Engineering, ESCE 2021

作者： Zhou, Jian Zhang, Tao Li, Liming Guo, Zhipeng Shi, Qiancheng China Construction Science and Technology Group Co. Ltd. Beijing100195 China Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin150090 China

Prefabricated shear walls are currently widely applied in mid-to-high-rise structures. As a new type of structural form of assembled shear walls, the ring connection assembled concrete shear wall has clear mechanical mechanism, easy construction and better performance and other significant advantages, which are gradually being applied in actual engineering. However, few systematic studies are carried on this new type of shear wall structure, and a complete theoretical system for guiding the design could not be given, especially in terms of mechanical mechanism and seismic performance, more detailed research work is needed. This paper uses numerical simulation as the main method to study the influence of different design variables such as shear span ratio, buckle size, axial compression ratio on the mechanical properties of the connection area in shear wall and the overall seismic performance of the structure. In this way, the theoretical basis for further optimizing the structural performance of the shear wall connection with ring connection. © Published under licence by IOP Publishing Ltd.

关键词： Shear walls

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Wave action by arrays of vertical cylinders with arbitrary smooth cross-section

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Journal of Hydrodynamics 2020年第1期32卷 70-81页

作者： Jia-bin Liu An-xin Guo Qing-he Fang Hui Li Hui Hu Peng-fei Liu Key Lab of Structures Dynamic Behavior and Conrol of the Ministry of Education Harbin Institute of Techno-logyHarbin 150090China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of TechnologyHarbin 150090China Depariment of Aerospace Engineering lowa State UniversityAmeslowa 50011USA China Railway Bridge Science Research Institute LtdWuhan 430034China

This paper presents an analytical model to solve the linear wave diffraction problem by arrays of bottom-mounted cylinders with arbitrary smooth *** on the assumption of ideal fluid and potential theory,the unknown coefficients of total velocity potential can be solved by system of linear equations,which are obtained from the boundary *** accuracy of the present method is verified by comparing it with the numerical tool in terms of the wave force and wave *** cylinders with different configurations are tested,the cross-section of which is circular with cosine *** results show that the proposed method could obtain an accurate prediction of the wave action with multiple cylinder ***,the diffraction wave is investigated on arrays of bottom-mounted cylinders with different cross-section and *** near-trapping problem with effects of the multi-body interaction are also investigated.

关键词： Wave diffraction cylinder array arbitrary smooth cross-section analytical solution

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Characteristics of aerodynamic force and flow structure behind single box girder under isolated slit control

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Journal of Central South University 2022年第8期29卷 2542-2557页

作者： CHEN Guan-bin CHENWen-li Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of TechnologyHarbin 150090China Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of TechnologyHarbin 150090China

An isolated slit was placed in a single box girder to obtain passive leading-edge suction and trailing-edge jet flow to control the unsteady aerodynamic force and modify the flow *** Great Belt East Bridge was used as a physical model at a geometric scale of 1:*** tunnel experiments were conducted at an incoming airflow speed of 10 m/s,and the Reynolds number was calculated as 2.3×104 using the test model height and wind *** surface pressure distribution was measured,and the aerodynamic force acting on the test model with and without the isolated slit was calculated by integrating the pressure *** was found that the control using an isolated slit can dramatically decrease the fluctuating surface pressure distribution and aerodynamic *** analysis on the power spectral density of the lift force revealed that the isolated slit accelerated vortex ***,high-speed particle image velocimetry was used to investigate the wake flow structure behind the test model.A vortex separated from the upper surface was pushed to a lower location and the wake flow structure was modified by the isolated slit.A proper orthogonal decomposition(POD)of the flow field showed that the first two POD modes in the controlled case contributed less energy than those in the uncontrolled case,indicating that more energy was transferred to higher modes,and small-scale vortices had more energy.A secondary instability structure was found in the wake flow for a nondimensional jet momentum coefficient J of 0.0667.

关键词： single box girder isolated slit aerodynamic force proper orthogonal decomposition(POD)mode

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大型液化天然气储罐在冲击荷载下的动力响应数值研究（英文）

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2019年第11期20卷 823-837页

作者： Chen YAN Xi-mei ZHAI Yong-hui WANG Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of TechnologyHarbin 150090China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of TechnologyHarbin 150090China

目的:研究冲击荷载各参数对于液化天然气(LNG)储罐的动力响应结果,定义LNG储罐受到冲击荷载时的破坏模式,并分析不同破坏模式下的破坏机理,为工程防御冲击荷载提供有效的理论研究基础。创新点:1.建立精细化的LNG储罐有限元模型;2.定义LN... 详细信息

目的:研究冲击荷载各参数对于液化天然气(LNG)储罐的动力响应结果,定义LNG储罐受到冲击荷载时的破坏模式,并分析不同破坏模式下的破坏机理,为工程防御冲击荷载提供有效的理论研究基础。创新点:1.建立精细化的LNG储罐有限元模型;2.定义LNG储罐在冲击荷载下的破坏模式并揭示其破坏机理;3.提出损伤因子Df可区分三种冲击破坏模式。方法:1.通过有限元模拟,进行冲击荷载的参数分析,得到不同冲击荷载对于LNG储罐的动力响应(图6和7);2.根据数值模拟结果,定义LNG储罐受到冲击荷载时的破坏模式(图8),并分析其破坏机理(图10和11);3.通过经验公式验算LNG储罐抵御冲击荷载的可靠性。结论:1. LNG储罐薄弱部位为外罐和环梁及底板的连接部位;2. LNG储罐受到冲击荷载的破坏模式分为局部变形、混凝土剥落和穿透三种;本研究得到了各种破坏模式下的破坏机理,并定义了损伤因子Df来区分三种破坏模式;3.通过经验公式验算,LNG储罐可以抵御英国规范建议的冲击荷载和法兰的冲击;DOE-standard公式计算结果最为保守。

关键词： LNG储罐冲击动力响应数值模拟破坏机理

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Vision-based multi-level synthetical evaluation of seismic damage for RC structural components: a multi-task learning approach

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Earthquake Engineering and Engineering Vibration 2023年第1期22卷 69-85页

作者： Xu Yang Qiao Weidong Zhao Jin Zhang Qiangqiang Li Hui Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and InformationTechnology Harbin Institute of TechnologyHarbin 150090China Key Lab of Structures Dynamics Behavior and Control of the Ministry of Education Harbin Institute of TechnologyHarbin 150090China School of Civil Engineering Harbin Institute of TechnologyHarbin 150090China School of Civil Engineering and Mechanics Lanzhou UniversityLanzhou 730000China

Recent studies for computer vision and deep learning-based,post-earthquake inspections on RC structures mainly perform well for specific tasks,while the trained models must be fine-tuned and re-trained when facing new tasks and datasets,which is inevitably *** study proposes a multi-task learning approach that simultaneously accomplishes the semantic segmentation of seven-type structural components,three-type seismic damage,and four-type deterioration *** proposed method contains a CNN-based encoder-decoder backbone subnetwork with skip-connection modules and a multi-head,task-specific recognition *** backbone subnetwork is designed to extract multi-level features of post-earthquake RC *** multi-head,task-specific recognition subnetwork consists of three individual self-attention pipelines,each of which utilizes extracted multi-level features from the backbone network as a mutual guidance for the individual segmentation task.A synthetical loss function is designed with real-time adaptive coefficients to balance multi-task losses and focus on the most unstably fluctuating *** experiments and comparative studies are further conducted to demonstrate their effectiveness and *** results show that the proposed method can simultaneously recognize different structural components,seismic damage,and deterioration states,and that the overall performance of the three-task learning models gains general improvement when compared to all single-task and dual-task models.

关键词： post-earthquake evaluation multi-task learning computer vision structural component segmentation seismic damage recognition deterioration state assessment

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Strategic positioning of FRP anchors in frpstrengthened slabs 7

Strategic positioning of FRP anchors in frpstrengthened slab...

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7th International Conference on FRP Composites in Civil Engineering, CICE 2014

作者： Zhang, Huawen Smith, Scott T. Wang, Zhenyu Southern Cross University Australia Department of Engineering Southern Cross University Australia Key Lab of Structures Dynamic Behavior and Control Ministry of Education China School of Civil Engineering Harbin Institute of Technology Heilongjiang Harbin150090 China

ISBN: (纸本)9781771363082

A common problem associated with the strengthening of reinforced concrete (RC) structures with externally bonded fibre-reinforced polymer (FRP) composites is the ability of the FRP to prematurely debond. The installation of anchorage devices is an intuitive and logical means with which to enhance the debonding resistance of such strengthening systems, however, there are limited comprehensive experimental studies to date. Anchors may also enhance the ductility of the strengthened member although experimental studies are particularly limited that investigate this phenomenon. This paper reports the results of seven reinforced concrete (RC) slab tests of which six slabs were strengthened in flexure with FRP plates. Five of the strengthened slabs were anchored with FRP anchors of different positioning and geometry. Depending on their position of installation, anchors are shown to enhance either the strength alone or both the strength and ductility of the FRP-strengthened slabs.

关键词： Anchors

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