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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

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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

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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

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

arXiv

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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

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A coupled model for vortex induced vibration of a circular cylinder with and without passive-jet flow control

A coupled model for vortex induced vibration of a circular c...

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第八届国际振动工程会议

作者： Guanbin Chen Wenli Chen Donglai Gao Xiangwei Min Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of Technology Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology

A coupled dynamic equation model, consisted by two parts: structural dynamic equation and the improved van der Pol equation(IVDPE), is established to predict the vortex induced vibration(VIV) response of circular cylinder dipped in the fluid environment. A classical structural dynamic equation is applied to describe the one degree-of-freedom vibration of a circular cylinder. The improved van der Pol equation is used to model the wake flow dynamics and the fluctuating aerodynamic force derived from the periodic alternating vortex shedding. The complete frequency component of aerodynamic forces, vibration amplitude and lock-in domains can be successfully predicted by the present coupled dynamic equation model. In addition, the passive jet pipes equipped on the circular cylinder to form the jet flow to suppress the VIV through the experimental method. The aerodynamic forces acting on the different sections far away from the passive jet pipes was obtained by the digital pressure measurement system. The aerodynamic force changed by the passive jet flow is consider into the coupled dynamic equation, and then the update coupled model is constructed and can predict the VIV of the circular cylinder with different spacing of adjacent passive jet pipes.

关键词： vortex-induced vibration alternating vortex shedding coupled model passive jet flow

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Fire resistance design of circular steel tube confined reinforced concrete columns 9

Fire resistance design of circular steel tube confined reinf...

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9th International Conference on Advances in Steel structures, ICASS 2018

作者： Yang, Hua Liu, Faqi Wang, Yuyin Zhang, Sumei Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of Ministry of Industry and Information Technology Harbin Institute of Technology Harbin China

ISBN: (纸本)9889914093

No study has been reported on fire performance of steel tube confined reinforced concrete (STCRC) columns. Hence fire behaviour of circular STCRC columns is investigated in this paper. Fire tests and numerical studies of circular STCRC columns are briefly introduced. Five full-scale specimens, including four circular STCRC columns and one CFST column, were tested to failure under combined thermal and mechanical loading. Temperatures across the section, displacement versus time curves and fire resistance of these columns were monitored and recorded. A finite element (FE) model was developed using the program ABAQUS, and validated against the test results. Based on test and FE results, a simplified design method was proposed for predicting fire resistance of circular STCRC columns exposed to ISO 834 standard fire condition. It was found that load ratio has significant influence on the fire resistance of circular STCRC columns. Compared with CFST columns and reinforced concrete columns, circular STCRC columns have higher fire resistance than the former and lower fire resistance than the latter. Copyright © 2018 by The Hong Kong Institute of Steel Construction.

关键词： Fire resistance

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Structural stochastic responses determination via a sample-based stochastic finite element method

arXiv

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arXiv 2021年

作者： Zheng, Zhibao School of Civil Engineering Harbin Institute of Technology Harbin150090 China Key Lab of Structures Dynamic Behavior and Control Harbin Institute of Technology Ministry of Education Harbin150090 China

This paper presents a new stochastic finite element method for computing structural stochastic responses. The method provides a new expansion of stochastic response and decouples the stochastic response into a combination of a series of deterministic responses with random variable coefficients. A dedicated iterative algorithm is proposed to determine the deterministic responses and corresponding random variable coefficients one by one. The algorithm computes the deterministic responses and corresponding random variable coefficients in their individual space and is insensitive to stochastic dimensions, thus it can be applied to high dimensional stochastic problems readily without extra difficulties. More importantly, the deterministic responses can be computed efficiently by use of existing Finite Element Method (FEM) solvers, thus the proposed method can be easy to embed into existing FEM structural analysis softwares. Three practical examples, including low-dimensional and high-dimensional stochastic problems, are given to demonstrate the accuracy and effectiveness of the proposed method. Copyright © 2021, The Authors. All rights reserved.

关键词： Random variables

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Axial compressive behavior of concrete-filled double-skin steel tubular columns with localized cracks

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structures 2025年 78卷

作者： Tong Zhang Shiqi Huang Shan Gao School of Civil Engineering Liaoning Technical University Fuxin Liaoning 123000 China Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin 150000 China

Concrete-filled double-skin steel tubular (CFDST) columns are widely used in a wide range of applications such as high-rise buildings, long-span bridges, offshore platforms, and heavy-duty industrial structures. However, due to the exposed steel tube, the external steel tube of CFDST columns is prone to cracking during long-term service, which affects their normal and safe use. This paper presents the mechanical behavior of CFDST columns with localized cracks. The peak load, failure mode, and full-range load-strain curve were produced according to the FE (finite element) model which were all line up with the findings of the experimental study. The impact of localized cracks on the CFDST stub struts in terms of peak load, stiffness, and flexibility is evaluated. The results indicate that the crack length, crack width, and crack depth exert minimal influence on the ultimate load and stiffness of the specimen. The crack length, crack width, and crack depth significantly impact the specimen's ductility. The ductility of the specimen is rapidly reduced by 30.9 %, especially when the steel tubes are penetrated due to corrosion. The crack angle barely impacts the breaking strength of the specimen. As the crack angle increases, the stiffness gradually decreases and the ductility gradually increases. A predictive technique of an error of less than 6 % is shown for the axial compressive capacity of CDFST pile columns with localized cracks. Finally, the GA-BP neural network model demonstrates its improved accuracy and generalization ability by comparing the genetic algorithm to a standard BP neural network, exhibiting higher the coefficient of determination and lower prediction errors on training and test datasets.

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Seismic behavior of FRP-retrofitted rectangular RC columns subjected to oblique horizontal earthquake actions

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Construction and Building Materials 2025年 482卷

作者： Zhu, Furui Zhang, Mengjie Zhang, Dawei Wang, Daiyu Wang, Zhenyu Zhang, Yaodong 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 Department of Civil Construction and Environmental Engineering North Dakota State University Fargo58102 United States School of Civil Engineering Yantai University Yantai264005 China

Externally wrapped fiber-reinforced polymer (FRP) confinement has proven effective in improving the seismic performance of reinforced concrete (RC) columns. However, existing seismic design recommendations are primarily based on quasi-static cyclic test results applied along the principal axis of the column section, which cannot accurately reflect the true characteristics of earthquakes. In this study, two 1/2-scale FRP-retrofitted rectangular RC columns were subjected to shaking table tests with ground motion input directions at 30° and 60° to the strong axis of the cross-section, respectively. The seismic performance, including damage mode, natural frequency, acceleration, displacement and strain response, torsional effect, and energy dissipation, was thoroughly analyzed. The result found that FRP-retrofitted rectangular RC columns exhibited completely different damage modes under shaking table tests compared to quasi-static loading, from previous ductile flexural failure to unfavorable flexural-shear-torsional failure, with more and wider cracks, more significant deformation, and more severe damages. These findings suggest that conclusions drawn from quasi-static tests tend to overestimate the retrofitting effect of FRP, and retrofitting only the plastic hinge zone of RC columns is insufficient to ensure structural safety, which should be considered in future seismic strengthening design criteria for RC structures. © 2025

关键词： Earthquake effects

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Early-Age Hydration Heat Evolution and Kinetics of Portland Cement Containing Nano-Silica at Different Temperatures

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SSRN 2022年

作者： Bai, Shuai Guan, Xinchun Li, Guoyu Key Lab of Structures Dynamic Behavior and Control The Ministry of Education Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters The Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China Harbin Institute of Technology Harbin150090 China State Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences Lanzhou730000 China

This study investigated the influence of nano-silica dosages and hydration temperatures on the early-age hydration heat of cement using isothermal calorimetry, and a hydration kinetics model was used to analyze the nucleation and growth rates of hydrates. The calorimetry results show that the addition of nano-silica and the increase of hydration temperature can accelerate the process of hydration reaction. As the dosage of nano-silica increases, the induction period decreases, the acceleration period and exothermic rate peak value increase. The fast pozzolanic effect of nano-silica is responsible for accelerating the hydration reaction. However, the excessive addition (5%) of nano-silica may form many agglomerations, thereby inhibiting the modification effect of nano-silica on the cement hydration. The simulating results of kinetic parameters show that, at three hydration temperatures, the nucleation rate of hydrates increase with the increasing of nano-silica dosages, which indirectly confirms the nucleation effect of nano-silica in the early-age hydration. At 20 °C and 30 °C, the growth rate of hydrates also increases with the increasing of nano-silica dosages. At 40 °C, the growth rate of hydrates is decreased gradually, possibly due to the lack of sufficient Ca2+ and H2SiO42-. In addition, the nucleation rate is more sensitive and the growth rate is less sensitive to the hydration temperature. © 2022, The Authors. All rights reserved.

关键词： Hydration

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