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An Adaptive Substructure-Based Model Order Reduction Method for Nonlinear Seismic Analysis in OpenSees

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Computer Modeling in Engineering & Sciences 2020年第7期124卷 79-106页

作者： Jian Wang Ming Fang Hui Li Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of TechnologyHarbin150090China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of TechnologyHarbin150090China College of Shipbuilding Engineering Harbin Engineering UniversityHarbin150001China.

Structural components may enter an initial-elastic state,a plastic-hardening state and a residual-elastic state during strong seismic *** the residual-elastic state,structural components keep in an unloading/reloading stage that is dominated by a tangent stiffness,thus structural components remain residual deformations but behave in an elastic *** has a great potential to make model order reduction for such structural components using the tangent-stiffness-based vibration modes as a reduced order *** this paper,an adaptive substructure-based model order reduction method is developed to perform nonlinear seismic analysis for structures that have a priori unknown damage *** method is able to generate time-varying substructures and make nonlinear model order reduction for substructures in the residual-elastic *** finite element program OpenSees has been extended to provide the adaptive substructure-based nonlinear seismic *** the low level of OpenSees framework,a new abstract layer is created to represent the time-varying substructures and implement the modeling process of *** the high level of OpenSees framework,a new transient analysis class is created to implement the solving process of substructure-based governing *** with the conventional time step integration method,the adaptive substructure-based model order reduction method can yield comparative results with a higher computational efficiency.

关键词： Adaptive substructure modeling model order reduction nonlinear seismic

Pretreated Lightweight Aggregates for Self-Healing Concrete Exposed to Calcium Hydroxide-Rich Sewage

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SSRN 2022年

作者： Li, Jinglu Guan, Xinchun Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters The Ministry of Industry and Information Technology Key Lab of Structures Dynamic Behavior and Control The Ministry of Education Harbin Institute of Technology Harbin150090 China School of Civil Engineering Harbin Institute of Technology Harbin150090 China

Wastewater concrete pipes are prone to cracking, causing deterioration in durability. As an acidic effluent treatment agent, calcium hydroxide is widely applied in sewage pipes. Based on the above background, this study investigated the self-healing behavior of the mortar containing pretreated lightweight aggregates in calcium hydroxide-rich sewage. Ceramsites were previously treated by impregnating with sodium silicate and encapsulating. Then, the mortar mixed with pretreated ceramsites was pre-cracked and exposed to water, Ca(OH)2 solution and Ca(OH)2 solution/dry cycles. The healing efficiency was evaluated by mechanical test, water absorption and crack visual observation. Results showed that the mortar exposed to Ca(OH)2 solution/dry cycles exhibited the most dominant healing efficiency. After healing for 30 days, the recovery rate of strength and reduction rate of sorptivity coefficient were 65% and 68%, respectively. The closure rate of the crack of 0-250 μm in width exceeded 80%. The area healing rates of the crack with an initial width of 200 μm reached up to 100%, 89% and 78%, respectively. Moreover, SEM and EDS indicated that healing products were mainly C-S-H gel and calcite. The accumulation and filling of products made crack self-healing, thereby improving the durability of the cracked mortar. © 2022, The Authors. All rights reserved.

关键词： Sewage

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

Static and Fatigue Performances of Clip Anchoring System For Frp Rod Used in Cable

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SSRN 2024年

作者： Xian, Guijun Niu, Yanzhao Tian, Jingwei Li, Chenggao Yue, Qingrui Guo, Rui Key Lab of Structures Dynamic Behavior and Control Harbin Institute of Technology Ministry of Education Heilongjiang 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 School of Civil Engineering Harbin Institute of Technology Heilongjiang Harbin150090 China Research Institute of Urbanization and Urban Safety School of Civil and Resource Engineering University of Science and Technology Beijing Beijing China

To obtain the static and fatigue performances and provide the design parameters of FRP rod for the application in cable structures. In the present paper, the design and preparation method of steel clip anchor, steel clip anchor with aluminum sleeve and adhesive interlayer are presented. The effect of taper difference, preload and anchor type on static and fatigue performances is studied by tensile and fatigue test, and the optimal design and application parameters of anchor are obtained. The results show that the peak shear stress of the rod at the front end of anchor can be reduced effectively by setting 0.1 ° taper difference, and the bearing capacity of anchor is increased by 5.3%-40.7% compared with 0 ° and 0.2 ° taper difference. The slippage of anchor can be reduced effectively with the increase of preload, which improves the critical slippage load of anchor. In addition, the stress concentration of rod inside the anchor can be reduced with the added of low modulus adhesive layer between steel clip and rod, which reduces the sensitivity of tensile performances to taper difference and delays the fatigue damage accumulation process of rod inside the anchor, the anchoring efficiency and fatigue resistance increases by 10.9% and 61.4% compared with steel clip anchor, respectively. © 2024, The Authors. All rights reserved.

关键词： Fatigue testing

Water absorptivity and frost resistance performance of self-ignition coal gangue autoclaved aerated concrete

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Journal of Infrastructure Preservation and Resilience 2021年第1期2卷 1-10页

作者： Cong, Xinyu Tan, Yiqiu Lu, Shuang Wang, Zhaojia Huang, Tianyong School of Transportation Science and Engineering Harbin Institute of Technology Huanghe Road 73 Harbin150090 China School of Civil Engineering Harbin Institute of technology Harbin150090 China Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education 9 Harbin Institute of Technology Harbin150090 China State Key Laboratory of Solid Waste Reuse for Building Materials Beijing Building 11 Materials Academy of Science Research Beijing100041 China

Self-ignition coal gangue (SCG) used as one of precursors to fabricate autoclaved aerated concrete (AAC). Aiming at studying water absorptivity and frost resistance performance of SCG-based AAC (SCGAAC), three-period water absorption tests and freeze-thaw tests were carried out and the corresponding results were recorded and analyzed. In order to modify the water absorptivity of SCGAAC, foam stabilizer was applied to adjust pore structure while calcium stearate was expected to change hydrophilic feature of SCG. It was demonstrated that the compressive strength of SCGAAC containing foam stabilizer or calcium stearate declined at different levels. For water absorption, foam stabilizer failed to decrease the water content and even increased water absorption rates. Calcium stearate controlled water absorption rate successfully although the ultimate water content hardly reduced. All of the SCGAAC samples exhibited intact appearance after 50 freeze-thaw cycles and showed excellent frost resistance performance. Three models were proposed to predict water absorptivity and frost resistance performance of SCGAAC and the corresponding prediction results matched test resulted well. © The Author(s) 2021.

关键词： Coal

Effects of cooking oil on the shrinkage-reducing of high-strength concrete

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Results in Materials

Results in Materials 2024年 23卷

作者： Huo, Yanlin Dong, Xinhong Gao, Yang Xu, Xiaodong Zeng, Liang Wu, Yuanchao Zhao, Yunhui Yang, Yingzi Su, Qunshan Huang, Jinguang Lu, Dong School of Civil Engineering Harbin Institute of Technology Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of Technology Postdoctor Workstation Henan D.R. Construction Group Research and Development Center Henan Qingshui Construction Technology Co. Ltd.

Autogenous shrinkage is a serious problem for high-strength concrete, which may lead to early-age cracking. Shrinkage-reducing agents are typically used to mitigate the autogenous shrinkage of concrete. However, some negative effects, such as unstable workability and the reduction of compressive strength, will be caused. In this study, emulsified or plain cooking oil is used as a shrinkage-reducing agent in low water-binder ratio concrete. Deformational behaviours of concrete with cooking oil and normal commercially available shrinkage-reducing agent are investigated. Experimental results show that the utilization of cooking oil could significantly reduce the autogenous shrinkage of high-strength concrete due to the reduction of surface tension. Additionally, emulsified cooking oil is better than normal shrinkage-reducing agents and plain cooking oil in many aspects of the concrete. Micro-structure of the concrete with different shrinkage-reducing agents is also observed. Emulsified cooking oil is considered a promising admixture for the mitigation of autogenous shrinkage of high-strength concrete. © 2024 The Authors

关键词： Autogenous shrinkage Cooking oil High strength concrete Shrinkage reducing agent

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

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