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Comparative study and optimal selection for different cable-stiffened latticed shells

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Thin-Walled structures 2022年 181卷

作者： Zhao, Lin Cao, Zhenggang Wang, Zhicheng Fan, Feng Key Lab of Structures Dynamic Behaviour and Control of the Ministry of Education Harbin Institute of Technology Harbin150090 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China

The cable-stiffened latticed shell can be constructed in varied structural forms by diverse types of single-layer latticed shells and cable-strut systems. So, to provide references for model selection, this paper studied the efficient combination of latticed shells and cable-strut systems in different boundary conditions and proposed a performance evaluation method. The general modeling process was illustrated firstly, and several new structural forms with folded curved surfaces were proposed. Then, based on the improved equilibrium matrix theory, the force-finding analysis was carried out for the initial state, which can guarantee actual mechanical properties in the numerical model. Thus, the overall stiffness, the bearing capacity, and the cable reinforcement effect were obtained through the nonlinear stability analysis. And for the optimal selection from multiple structural forms, AHP-TOPSIS was used to judge the latticed shell system for the first time. The comprehensive structural performances were evaluated and ranked by this multi-attribute decision-making method. Finally, the results showed that the complicated cable-strut system could not necessarily lead to higher structural efficiency. Regardless of the cable-strut layouts, the spherical cable-stiffened latticed shell had a high bearing capacity when the ribbed grid was adopted. For the cylindrical structure, the folded latticed shell divided by orthogonal grids maximized the role of in-plane cables and was considered the best choice. © 2022 Elsevier Ltd

关键词： Cables

The Deformation of C–S–H Gel and its Link with Length Change of Cement Pastes on Drying and Resaturation

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SSRN 2023年

作者： Zhang, Xiaoyu Qiao, Jing Feng, Jingjing Xu, Shilang Zhou, Chunsheng Zeng, Qiang Key Lab of Structures Dynamic Behavior and Control Ministry of Education Harbin Institute of Technology Harbin150090 China School of Civil Engineering Harbin Institute of Technology Harbin150090 China College of Water Conservancy and Civil Engineering Shandong Agricultural University Taian271018 China College of Civil Engineering and Architecture Zhejiang University Hangzhou310058 China

Drying shrinkage of cement pastes (CPs) facilitating superficial cracking deserves primary concern when handling durability performance. In order to further clarify shrinkage mechanism, the changes of mass, length and pore water allocation of two mature CPs were monitored principally through non-destructive low-field NMR relaxation technique. Experimental results revealed that, heat treatment under hot water slightly coarsens the pore structure of CPs through modifying the morphology of C-S-H gel, but reduces shrinkage during first drying remarkably. During drying at 80% RH, although both interlayer and gel pores are saturated, they loss their water progressively at reducing rates. At the expense of reducing interlayer space, the contraction of gel pores is partly and even entirely compensated. When drying at lower 43% RH, interlayer pores still saturated are compacted more significantly with reducing size and volume. The compaction of interlayer pores is at the micro-structural origin and dominates drying shrinkage of CPs. © 2023, The Authors. All rights reserved.

关键词： Drying

dynamic Responses and Cumulative Damage of Coastal Bridges Subjected to Extreme Sequential Earthquake-Tsunamis

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SSRN 2024年

作者： Zhu, Deming Dong, You Feng, Ruiwei Li, Yaohan Zhai, Changhai Department of Civil and Environmental Engineering The Hong Kong Polytechnic University Hong Kong Research Institute for Sustainable Urban Development The Hong Kong Polytechnic University Hong Kong Department of Construction and Quality Management Hong Kong Metropolitan University Hong Kong Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin150090 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disaster The Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China

Coastal bridges, as vital components of transportation networks, are vulnerable to damage from successive earthquake-tsunami (EQ-TS) events in rapidly developing coastal hazard-prone cities. Understanding how these bridges perform under the combined effects of earthquakes and tsunamis is crucial. Though studies have investigated coastal buildings facing these hazards, there is limited research on bridges experiencing extreme EQ-TS events, especially on the generation of load sequences, dynamic structural responses, and cumulative damage assessment. To overcome these limitations, this study aims to thoroughly examine the dynamic behavior of reinforced concrete coastal bridges subjected to successive EQ-TS hazards. To generate practical sequential EQ-TS loads, records of the 2011 Tohoku earthquake and resulting tsunami heights, which are calculated based on the earthquake magnitude and epicentral distance, are utilized for analyses. The tsunami wave load time series for each earthquake record is created using a high-fidelity computational fluid dynamics model. Nonlinear time-history analyses are then performed for the bridge model in OpenSees under the synthetic EQ-TS sequences, quantifying structural responses and cumulative damage. Moreover, the comparative results of structural performance under single and successive hazard scenarios are presented and discussed. Results indicate that successive EQ-TS hazards not only induce much larger structural responses as compared to a single EQ hazard, but also produce considerable residual displacements for both bearings and decks. The wave height is more appropriate than the peak ground acceleration as an individual intensity measure for predicting the cumulative damage of bridges under cascading EQ-TS hazards. Relying solely on peak responses for assessing the dynamic performance of piers under successive EQ-TS sequences may underestimate the actual damage. © 2024, The Authors. All rights reserved.

关键词： Earthquakes

Efficient single-grid and multi-grid solvers for real-space orbital-free density functional theory

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arXiv

arXiv 2022年

作者： Bu, Ling-Ze Wang, Wei School of Civil Engineering Harbin Institute of Technology Harbin150090 China Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin150090 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China

To improve the computational efficiencies of the real-space orbital-free density functional theory, this work develops a new single-grid solver by directly providing the closed-form solution to the inner iteration and using an improved bisection method to accelerate the line search process in the outer iteration, and extended the single-grid solver to a multi-grid solver. Numerical examples show that the proposed single-grid solver can improve the computational efficiencies by two orders of magnitude comparing with the methods in the literature and the multi-grid solver can improve the computational efficiencies even once for the cases where high-resolution electron densities are needed. © 2022, CC BY-NC-SA.

关键词： Computational efficiency

Effects of Various Connectors on the Whole-Life-Cycle Energy Consumption of Sandwich Wall Panels in Five Thermal Zones of china

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SSRN 2022年

作者： Dong, Xianzhang Lu, Yiming Xiao, Huigang Liao, Juan School of Civil Engineering Harbin Institute of Technology Harbin150090 China Key Lab of Structures Dynamic Behavior and Control Ministry of Education Harbin Institute of Technology Harbin150090 China China Construction Second Engineering Bureau. Ltd 100160 China

Connectors are not only an important mechanical component of sandwich wall panels (SWPs), but they also contribute to SWP energy loss because they penetrate thermal insulation layers. Reducing the energy consumption (EC) generated by connectors is critical for improving the energy-saving efficiency of SWPs throughout their life cycle. The mechanical and thermal parameters of connectors, structural layers, and insulation layers all have a coupling effect on the EC of connectors in the SWPs studied in this study. First, a connector diameter calculation model and a three-dimensional finite element (3-DFE) model were developed to investigate the mechanism of various connectors' effects on the thermal performance (TP) of SWPs with different structural and insulation layers. It was discovered that increasing the connector shear strength could reduce energy loss by reducing the connector size, and connector energy loss could also be improved by lowering the connector thermal conductivity and increasing the thermal resistance of the structural layers. Then, based on TP, a life cycle assessment (LCA) model was developed. Using five thermal zones in china as research subjects, it was discovered that the effects of connectors on the whole-life-cycle EC of SWPs depend on the value of degree days (DD). The connector manufacturing EC dominated the whole-life-cycle EC in an area with a low DD value. Reduced thermal conductivities of connectors, structural layers, and insulation layers could significantly improve the effects of connectors on the whole-life-cycle EC of SWPs in an area with a high value of DD. These findings are critical for the development of effective SWPs. © 2022, The Authors. All rights reserved.

关键词： Energy utilization

Cathode Potential Regulates the Microbiome Assembly and Function in Electrostimulated Bio- Dechlorination System

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SSRN 2022年

作者： Li, Zhi-Ling Cao, Di Shi, Ke Liang, Bin Zhu, Zhongli Liu, Wenzong Nan, Jun Sun, Kai Wang, Ai-Jie State Key Laboratory of Urban Water Resources and Environment School of Environment Harbin Institute of Technology Harbin150090 China Shenzhen518055 China Key Lab of Structures Dynamic Behavior and Control of China Ministry of Education School of Civil Engineering Harbin Institute of Technology Harbin150090 China

Mechanism of microbiome assembly and function driven by cathode potential in electro-stimulated microbial reductive dechlorination system remain poorly understood. Here, core microbiome structure, interaction, function and assembly regulating by cathode potential were investigated in a 2,4,6-trichlorophenol bio-dechlorination system. The highest dechlorination rate(24.30μM/d)was observed under-0.36Vwith phenol as a major end metabolite, while, lower (-0.56V) or higher (0.04Vor-0.16V)potentials resulted in 1.3~3.8 times decreased of dechlorination kinetic constant. The lower the cathode potential, the higher the generated CH4 , revealing cathode participated in hydrogenotrophic methanogenesis. Taxonomic and functional structure of core microbiome significantly shifted within groups of -0.36V and -0.56V, with dechlorinators ( Desulfitobacteriu , Dehalobacter ), fermenters ( norank_f_Propionibacteriaceae , Dysgonomonas )and cathode-utilizing methanogen ( Methanosarcina ) highly enriched, and the more positive interactions between functional genera were found. The lowest number of nodes and links and the highest positive correlations were observed among constructed sub-networks classified by function, revealing simplified and strengthened cooperation of functional genera driven by group of -0.36 V. Cathode potential plays one important driver controlling core microbiome assembly, and the low potentials drove the assembly of major dechlorinating, methanogenic and electro-active genera to be more deterministic, while, the major fermenting genera were mostly governed by stochastic processes. © 2022, The Authors. All rights reserved.

关键词： Dechlorination

Damage Detection of Transmission Tower Based on Stochastic Subspace and Statistic Model 3

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Damage Detection of Transmission Tower Based on Stochastic S...

3rd International Conference on Environmental Prevention and Pollution control Technologies, EPPCT 2021

作者： Xingjie, Wang Tingting, Yang Meigen, Cao Chong, Zheng Wensong, Zhou Yutong, Pang Wenzhou Power Supply Company of State Grid Zhejiang Province Wenzhou330300 China Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Heilongjiang Province Harbin150090 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters Ministry of Industry and Information Technology Harbin Institute of Technology Heilongjiang Province Harbin150090 China School of Civil Engineering North China University of Technology Beijing100144 China

During the long service period of the transmission tower, the severe environment, material aging and fatigue effects result in the damage accumulation and resistance fading of the transmission tower, which even lead to the structural failure. In this paper, a stochastic subspace-based damage detection algorithm combined with statistical model is proposed for the damage identification of transmission tower structures through processing and analysing its vibration signals. Based on the structural modal parameters identified from the structural vibration response, the nominal modal parameters are defined. Considering that the Hankel matrixes constructed by the system observability matrix and the system output covariance matrix have the same kernel space, the damage index sensitive to the modal parameters is constructed. In the manuscript, firstly, the damage index establishment method and process of the algorithm are presented;and then the vibration data of transmission tower structure simulation under different damage conditions are obtained through numerical simulations;finally, above data are analysed to obtain the damage identification results of transmission tower. The results show that the method proposed in this work can effectively identify the local damage of transmission tower structure. © Published under licence by IOP Publishing Ltd.

关键词： Stochastic systems

Reliability Assessment of Offshore structures Using Subset Simulation with Adaptive Standard Deviation for Mmh Algorithm with Two-Stage Delayed Rejection

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SSRN 2023年

作者： Ma, Junming Lan, Chengming Guo, Anxin Li, Hui National Center for Materials Service Safety University of Science & Technology Beijing Beijing100083 China Research Institute of Urbanization and Urban Safety School of Civil and Resource Engineering University of Science & Technology Beijing Beijing100083 China Key Lab of Structures Dynamic Behavior and Control Ministry of Education School of Civil Engineering Harbin Institute of Technology Harbin150090 China

This paper explores modified strategies for MMH in the subset simulation for reliability assessment in ocean engineering. To improve the sampling efficiency in complex distributions comprising correlated or non-normal variables, this study proposes a modified approach involving a two-stage delayed rejection and an adaptive STD for the proposal distribution based on MMH. The acceptance rate of the candidate sample in two-stage delayed rejection approach is derived based on the reversibility condition of Markov chain to reduce the repeated samples. Additionally, the STD for all accepted samples is used as the STD for the proposal, which dominates the sampling scale and increases the acceptance rate. The Neal’s normal distribution, the Banana-shaped bivariate distribution, and the correlated joint distribution for wind and wave are adopted to study the sampling efficiency and ergodicity for MMHDR, AMMHDR, and AMMHDDR. Furthermore, three sampling algorithms are employed to generate conditional samples for estimating the probabilities of base shear failure and system failure in jacket platforms. The results indicate that the AMMHDDR can enhance the sampling efficiency, especially for complex distributions with correlated variables. Also, the AMMHDDR can be used in SS to improve the accuracy and reduce the variation when estimating failure probabilities of offshore structures. © 2023, The Authors. All rights reserved.

关键词： Normal distribution

dynamic Characteristics and Force Analysis of Box Girder Under Tsunami Action Based On Level-Set Method

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SSRN 2024年

作者： Niu, Shilei Liu, Zhongxiang Guo, Tong Guo, Anxin Liu, Aimin School of Transportation Southeast University Nanjing210096 China Key Laboratory of Concrete and Prestressed Concrete Structures School of Civil Engineering Southeast University Nanjing210096 China Ministry-of-Education Key Laboratory of Structural Dynamic Behavior and Control School of Civil Engineering Harbin Institute of Technology Harbin150090 China China Energy Engineering Group Jiangsu No.1 Electric Power Construction Co. Ltd. Nanjing210001 China

Tsunamis pose significant threats to the safety of sea-crossing bridges. Understanding the dynamics of wave forces and girder responses during tsunami events is crucial for ensuring their safe maintenance. In this research, a 2D numerical flume with solitary waves was utilized to simulate tsunamis. The level-set method was used for the treatment of fluid-solid interface and free surface. The interaction between the tsunami and the bridge girder was replicated through real-time data exchange between the fluid and a spring-mass-damper system. Subsequently, the hydrodynamic behaviors of the fluid surrounding the box girder and the structural responses of the girder under tsunami conditions were examined through parametric analysis. Findings suggest that tsunami with larger wave height interacts with box girder for longer duration. The maximum resistance and moment occur at the instant when the fluid acts on the top plate. Considering fluid-structure interaction and bearing constraints, increasing bearing stiffness results in substantial reductions (79.28%~85.32%) in girder displacement. Additionally, the maximum horizontal displacement of the unsubmerged box girder exceeds that of the submerged state by 2.04mm. Moreover, horizontal forces on the box girder decrease by 19.25%~45.30%, while maximum horizontal compression and tension on the wave-facing side bearing decrease by 10.7%~14.8% and 25.7%~29.9%, respectively. The maximum compression is approximately 2.68~3.34 times the maximum tension. © 2024, The Authors. All rights reserved.

关键词： Numerical methods