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

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

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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

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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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Efficient structural seismic performance evaluation method using improved endurance time analysis

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Earthquake Engineering and Engineering Vibration 2019年第4期18卷 795-809页

作者： Li Shuang Liu Kun Liu Xiangyang Zhai Changhai Xie Fengwei Key Lab of Structures Dynamic Behavior 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

Evaluation of structural performance under seismic excitations from low intensity to high intensity is essential to verify the seismic resistant capacity of a structure, and usually carried out by the incremental dynamic analysis (IDA) method or pushover method. The recently developed endurance time (ET) method is another method that uses dynamic pushover excitations, i.e., endurance time acceleration function, to obtain results similar to those obtained by IDA or pushover methods with low computational cost and acceptable accuracy. This study proposes an improvement on the ET method by considering more restrictions for both the elastic and inelastic response spectra in the generation procedure, and by specifying a target duration. Four reinforced concrete frame structures with 4, 8, 12, and 16 stories are adopted to verify the accuracy of the improved method. Comparison of the results obtained by the proposed method, the ET method and the IDA method shows that the improved method has a higher accuracy than the ET method. For evaluation of structural responses under specifi c ground motion intensity, which is typically required in seismic design codes, the results obtained by the proposed method are compared with fi ve commonly used ground motion selection methods, and shows the proposed method provides acceptable accuracy for engineering applications.

关键词： seismic performance evaluation endurance time method inelastic response spectra target duration

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Development of dimensionless P-I diagram for curved SCS sandwich shell subjected to uniformly distributed blast pressure

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Frontiers of Structural and Civil Engineering 2019年第6期13卷 1432-1445页

作者： Yonghui WANG Ximei ZHAI 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

The curved steel-concrete-steel(SCS)sandwich shell was recently proposed to resist blast loading and it showed better blast resistant performance as compared to flat SCS sandwich shell via developing compressive force along the *** this paper,a dimensionless Pressure-Impulse(P-I)diagram was constructed as a convenient tool to predict the damage level of curved SCS sandwich shell subjected to uniformly distributed blast *** curved SCS sandwich shell was equivalent to a single-degree-oMreedom(SDOF)system and the equation of motion was established by employing the Lagrange's *** construct the dimensionless P-I diagram,the energy balance method was utilized to yield the pressure and impulse asymptotes and the responses in the dynamic response regime were obtained via employing the SDOF ***,the finite element method was employed to validate the developed dimensionless P-I ***,the procedures of using the constructed dimensionless P-I diagram to quickly conduct the blast resistant design of curved SCS sandwich shell were presented.

关键词： blast loading curved steel-concrete-steel sandwich shell Pressure-Impulse diagram single-degree-of-freedom method finite element analysis

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

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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.

关键词： Bearing capacity Compression behavior Concrete-filled double-skin steel tubular Localized cracks

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Aerodynamic design and analysis for offshore wind turbine blade model

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Energy 2025年 330卷

作者： Ziyang Zhang Wen-Li Chen Jiabin Liu 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 Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin 150090 China

Model experiments are essential for designing and analysing offshore wind turbines. During the scaling process of the model, the rotor thrust significantly decreases due to the Reynolds number effect. As wind turbines increase in size, blade length also gradually increases. The scaling ratio of the model decreases due to laboratory size constraints, affecting the structural loading characteristics. Therefore, this study performs an aerodynamic design for model blades, considering the Reynolds number effects and geometric dimensions. The optimised blade satisfies the scaled model's thrust requirements when its length is shorter than the scaled prototype blade. We employed the low Reynolds number airfoil SG 6043 to optimise the model blade. The geometric parameters of the optimised blades were calculated using the blade element momentum theory and pattern search method. Wind tunnel experiments were conducted on the optimised blade to analyse the variation characteristics of rotor thrust. The research results show that the numerical calculation results of rotor thrust generally align with the experimental results. The rotor thrust of the optimised blades was significantly enhanced, meeting the scaled model's thrust requirements. The error between the optimised blade's rotor thrust and the scaled target value is less than 2 %.

关键词： Aerodynamic design Optimised blade Reynolds number effects Rotor thrust

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Experimental Study of High-Temperature Resistance of Alkali-Activated Slag Crushed Aggregate Mortar

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SSRN 2022年

作者： Huang, Wenxuan Wang, Ying Zhang, Yaming Zheng, Wenzhong School of Civil Engineering Harbin Institute of Technology Haihe Road #202 Nangang District Harbin150090 China Key Lab of Structures Dynamic Behavior and Control Ministry of Education Key Lab Smart Prevention and Mitigation of Civil Engineering Disasters Ministry of Industry and Information Technology School of Civil Engineering Harbin Institute of Technology Haihe Road #202 Nangang District Harbin150090 China

In this research, a special type of mortar with alkali-activated slag as cementitious material was examined, which had the characteristics of high strength, high temperature resistance and environmental protection. Its aggregates consisted of crushed and sieved particles of alkali-activated slag paste. The compressive strengths of 126 cubic and 126 prismatic specimens during and after high-temperature treatment were investigated. The test results showed that both the compressive and flexural strengths of the mortar during and after high-temperature treatment decreased with increasing temperature. Moreover, the compressive strength of the mortar after high-temperature treatment was higher than that during the treatment in which strength grade and temperature were constant. The high-temperature strength loss of the mortar was also found to be lower than that of concrete. The formulated equations for calculating the compressive and flexural strengths during and after high-temperature treatment provided a basis for evaluating the fire resistance of this new type of masonry material. The microstructure and composition of the mortar were analyzed using scanning electron microscopy with energy-dispersive spectrometry and X-ray diffraction. At 600 ℃, the mortar gradually produced new melilite products. © 2022, The Authors. All rights reserved.

关键词： Compressive strength

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Genetic algorithm-based shape optimization of plates for reducing wave loads on cylindrical structure

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Ocean Engineering 2025年 337卷

作者： Jingbo Qing Peimian Du Pengwei Bei Jiabin Liu Anxin Guo 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 Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin 150090 China

Theoretical studies have shown that incorporating protective plates into cylindrical structures reduces wave-induced loads. This study applies the Boundary Element Method (BEM) to analyze linear wave-structure interactions and employs the Genetic Algorithm (GA) for global optimization to determine the optimal plate shape. Experimental analyses were conducted under various wave conditions to further evaluate the performance of the protective plates. The evaluation included three distinct types of protective plates: the GA-optimized curved plate, the flat plate, and the porous plate. The results show that all three protective plate types effectively reduce wave-induced loads but also increase wave run-up. Compared to flat and porous plates, the optimized curved plate performs better in reducing bending moments. The effectiveness of the protective plates is not significant near k 0 R = 0.5 , and may even increase wave loads. The influence of protective plates resembles wave shoaling, altering wave forms and dissipating energy. Wave impact and breaking can occur during this process, highlighting the limitations of linear potential flow theory in modeling interactions between waves and protective plates.

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