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Detecting Multiple Change Points in Distributional Sequences Derived from structural Health Monitoring Data: An Application to Bridge Damage Detection

arXiv

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arXiv 2023年

作者： Lei, Xinyi Chen, Zhicheng 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 Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin150090 China School of Civil Engineering Harbin Institute of Technology Harbin150090 China

Detecting damage in critical structures using monitored data is a fundamental task of structural health monitoring, which is extremely important for maintaining structures' safety and life-cycle management. Based on statistical pattern recognition paradigm, damage detection can be conducted by assessing changes in the distribution of properly extracted damage-sensitive features (DSFs). This can be naturally formulated as a distributional change-point detection problem. A good change-point detector for damage detection should be scalable to large DSF datasets, applicable to different types of changes, and capable of controlling for false-positive indications. This study proposes a new distributional change-point detection method for damage detection to address these challenges. We embed the elements of a DSF distributional sequence into the Wasserstein space and construct a moving sum (MOSUM) multiple changepoint detector based on Fréchet statistics and establish theoretical properties. Extensive simulation studies demonstrate the superiority of our proposed approach against other competitors to address the aforementioned practical requirements. We apply our method to the cable-tension measurements monitored from a long-span cable-stayed bridge for cable damage detection. We conduct a comprehensive change-point analysis for the extracted DSF data, and reveal interesting patterns from the detected changes, which provides valuable insights into cable system damage. Copyright © 2023, The Authors. All rights reserved.

关键词： Damage detection

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Transfer the Evaluation of Energy-Efficient Building Retrofitting: A Sweden-china Empirical Study

SSRN

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SSRN 2023年

作者： Man, Qingpeng Yu, Haitao Feng, Kailun Olofsson, Thomas Lu, Weizhuo Department of Construction Management Key Lab of Structures Dynamic Behavior and Control The Ministry of Education Harbin Institute of Technology Harbin150009 China Intelligent Human-Buildings Interactions lab Department of Applied Physics and Electronics Umeå University Umeå90187 Sweden

Energy-efficient retrofitting is regarded as a promising and widely applicable approach to reducing the energy use and carbon emissions of existing buildings. It is critical to properly evaluate and compare the performances of different energy-efficient retrofitting strategies. Data-driven modelling based on large building performance datasets is an effective method for such evaluations. However, it could be challenging to apply this approach to buildings from data-poor areas where local building performance datasets have not been well-established, which means the data falls short of the high demand for building retrofitting on a global level. To address this, a transfer learning approach is proposed in this study that can evaluate the performance of buildings without local well-established building performance datasets. The proposed approach is applied in the Swedish-Chinese empirical study that relies on the Swedish dataset to transfer and predict the building performance in china without well-established datasets. It was achieved by applying fuzzy C-means clustering and a neural network (FCM-BRBNN) to pre-train the evaluation model based on the Swedish dataset. Then, the proposed approach collects a small sample of Chinese buildings in the data-poor area and transfers the model to local building performance prediction. The results show that the transfer learning approach can reliably predict the performance of building retrofitting in data-poor areas with only hundreds of local building samples. As such, this study provides a novel methodology that can support the evaluation and comparison of retrofitting strategies in data-poor religions and countries, being pivotal for the international collaboration required to stimulate the global energy-efficiency transformation. © 2023, The Authors. All rights reserved.

关键词： Large dataset

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Engineering Interfacial Transition Zone with Polymer Nanocomposites: Break the Dilemma between Strength and Damping

SSRN

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SSRN 2023年

作者： Li, Cheng Tang, Zhuo Zhong, Jing 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 Key Lab of Smart Prevention and Mitigating of Industry and Information Technology Harbin Institute of Technology Harbin150090 China

The damping performance of mortar/concrete is typically promoted by randomly hybridizing with an excessive mass of soft polymers at the cost of strength. We propose a strategy to break the typically observed dilemma between strength and damping by coating aggregates with a thin layer of polyacrylic ester/carbon nanotube (PAE/CNT) nanocomposite, which was readily achieved by dip coating. The coated nanocomposite with high modulus is subjected to high stress at ITZ upon external load due to stress concentration, greatly enhancing its energy dissipation capability. The friction at the nano-interface between CNT and polymer matrix further contributes to the much-improved damping, while the coating layer can densify the ITZ thus increases the strength of the concrete. With an optimal coating mass of 5 mg/g, the compressive strength and loss factor at 28 days are increased by 21.7% and 33.3%, respectively. © 2023, The Authors. All rights reserved.

关键词： Carbon nanotubes

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Effect of Thermal Radiation on the Thermal Properties of Parietodynamic Walls

SSRN

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SSRN 2023年

作者： Dong, Xianzhang Lin, Baochen Xiao, Huigang Liu, Min 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 Heilongjiang Heijianyi Construction Engineering Co. Ltd 150040 China

The parietodynamic wall, a type of dynamic insulation, has been identified as an effective technology to reduce energy loss in buildings by recovering heat and cold energy through forced convection. However, current research on the thermal performance of parietodynamic walls has neglected the influence of thermal radiation, a crucial factor in energy transfer within the air layer of the wall. To address this gap, a numerical model that couples thermal radiation, heat transfer in solids and fluids, and turbulence is established to evaluate the effect of thermal radiation. Our results indicate that emissivity, the thermal resistance of the insulation layer, and air layer thickness significantly affect the proportion of thermal radiation in heat transfer. Specifically, when the emissivity is 1, the contribution ratio of thermal radiation to the heat transfer coefficient (HTC) of the parietodynamic wall is by up to 80.7%. Moreover, low thermal resistance of the insulation layer can increase the HTC by 268%-630% through thermal radiation gain. These findings improve our understanding of the effect of thermal radiation in parietodynamic walls, which would aid in the development of more energy-efficient buildings. © 2023, The Authors. All rights reserved.

关键词： Heat radiation

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Experimental Study on Flexural Performance of Ultra-High-Performance Concrete with Recycled Aggregate Co-Modified by Nano-Silica and Steel Fiber

SSRN

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SSRN 2023年

作者： Luo, Liang Shi, Jun Wang, Jianan Qu, Yiwen Dai, Bin School of Civil Engineering Central South University Changsha410075 China Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin150090 China School of Civil Engineering Harbin Institute of Technology Harbin150090 China

Expanding the application of defective recycled aggregates (RA) to ultra-high performance concrete (UHPC), it is necessary to modify them with nano-silica (NS) in conjunction with steel fibers (SF), and it is worthwhile to investigate the bending behavior under the typical characteristics of this new *** study investigates the flexural performance of recycled aggregate ultra-high-performance concrete (RA-UHPC) using a four-point bending test and analyzes the influence of RA substitution rates (0%, 50%, and 100%), SF content (0%, 1%, and 2%), and NS content (0%, 1%, 3%, and 5%) on its flexural toughness and microstructure. Additionally, digital image correlation (DIC) technology was employed to capture crack evolution during the test, and SEM microstructural analysis was used to elucidate the flexural mechanism of this fiber-nano composite concrete. The results show that the load-deflection curves of specimens without SF exhibit initial linear-elastic growth, followed by a sharp decrease in load after the peak without a distinct descending stage. In contrast, specimens with SF display three typical stages, with a smoother and flatter descending stage. The cross-distributed SF enhances post-peak ductility, transforming the failure behavior from quasi-brittle to ductile. Increasing SF content significantly enhances the flexural strength and toughness of the specimens, while an increase in RA substitution rate and NS content results in a slight reduction in flexural strength (fp). The changes in residual strength observed through both methods are consistent, with almost no residual strength in the brittle failure specimens. Moreover, DIC technology, relying on precise image capture, can predict crack positions before the peak load is reached. Finally, the microstructural analysis in SEM is combined to illustrate the flexural mechanism of this fiber-nanocomposite concrete. © 2023, The Authors. All rights reserved.

关键词： Image correlation

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Optimized Repairment Properties Of Wer-Cement Composite Material: An Experimental and Simulation Study

SSRN

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SSRN 2023年

作者： Li, Cong Xiao, Huigang Min, Liu Wang, Wei Xu, Fan School of Civil Engineering Harbin Institute of Technology Heilongjiang China 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 Heilongjiang Construction Group Co. Ltd Heilongjiang China

The demand for high-performance repair materials has significantly increased in modern society after the completion of infrastructure construction. However, current research on epoxy resin cement mortar composite lacks theoretical investigation of the proportion of epoxy resin and hardener to prepare a composite material with optimal performance, as it often relies on empirical and previous studies. To address this issue, this study employed E44 and D230 raw materials and determined through theoretical calculations that the optimal ratio for the composite material is 4:1. The best ratio and content were validated by various testing techniques, such as workability, mechanical properties, self-developed shear bond strength test, and impermeability performance. These analyses showed that the composite material's epoxy resin and hardener ratio should be 4:1, with a content of 30%. Additionally, the microstructure of the composite material was analyzed using various testing techniques, including SEM, SEM-EDS, XRD, FTIR, and MIP, to investigate its influence on the ITZ, composition, and pore structure. Furthermore, molecular dynamics simulation was conducted to analyze the mechanical properties, adsorption energy, MSD, and RDF of C-S-H and epoxy resin molecules (cross-linked structures) composite, explaining the effect of water molecules on the composite material from an atomic scale perspective. By combining experimentation and simulation, this study proposed a computationally based ratio design method, which could provide new ideas for research and development of WER-cement composite while created a simple shear bond strength testing method for repair materials. © 2023, The Authors. All rights reserved.

关键词： Epoxy resins

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Real-Time Seismic Damage Simulation for Urban Building Portfolio Based on Basic Building Information and Machine Learning

SSRN

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SSRN 2023年

作者： Li, Shuang Li, Changqing Huang, Yuwen Zhai, Changhai 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 Beijing Glory PKPM Technology Co. Ltd Beijing100013 China

Timely and accurate simulation of seismic damage of the urban building portfolio is important for pre-earthquake planning and post-earthquake rescue. This study proposes a real-time seismic damage simulation method for the urban building portfolio based on the multiple degree-of-freedom (MDOF) shear model and flexural-shear model established by basic building information and the machine learning. The formulas for predicting periods of six types of structures are proposed and the surrogate model-Ⅰ for predicting the key inter-story hysteretic parameters are established to optimize the MDOF models. The surrogate model-Ⅱ is established to rapidly predict the engineering demand parameters and damage states of structures under earthquakes. In terms of the generalization capability, an incremental learning strategy is advised to guarantee the accuracy of the surrogate model-Ⅱ in predicting the seismic damage of other urban building portfolios. The results in two city-scale cases show that the proposed method can achieve real-time seismic damage simulation of urban building portfolio with acceptable accuracy, and it’s not necessary to retrain or only needs minor additional training on the existing surrogate model when applied to other urban building portfolios. © 2023, The Authors. All rights reserved.

关键词： Machine learning

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A Study On Properties of Pu-Cement Composites Repairing Material for Seepage control and Plugging

SSRN

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SSRN 2023年

作者： Li, Cong Bai, Jinrong Jiang, Ying Xiao, Huigang Wang, Wei Xu, Fan School of Civil Engineering Harbin Institution of Technology Heilongjiang China 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 Heilongjiang Construction Group Co. Ltd Heilongjiang China

Composite grouting materials are increasingly becoming the focus of seepage control and plugging research, and in order to improve its mechanical properties and delayed hydration repairment effect without compromising its workability, PU-cement composites grouting materials, in which cement are not the main component, still, requiring a finer particle size and good shape. In this study, the ball-milled cement are prepared to combine with WPU and OPU, creating a new PU-cement composites grouting *** particle size distribution, early strength, and micro-structure of ball-milled cement were analyzed, then the best preparation process was determined as 120min ball-milling time and 0.03% grinding aid doping. The viscosity, swelling rate, bond strength, FTIR, XRD and micro-structure of the composites with different ratios of polymer/cement and OPU/WPU were then examined, especially, based on moisture distribution, a new method to evaluate the impermeability of repair materials is proposed, and the function of ball-milled cement in composites and the interaction mechanism between ball-milled cement and PU were discussed. The results showed that the best performance was achieved with the P/C ratio of 3:1 and 4:1, and the OPU/WPU ratio of 2:1 or 3:1, indicating that PU-cement grouting material can be an ideal choice for underground structure seepage control and plugging. © 2023, The Authors. All rights reserved.

关键词： Cements

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Mechanical Properties and Microstructure of Ultra-High-Performance Concrete Containing Recycled Aggregates Co-Modified with Steel Fibres and Nanosilica after Exposure to Elevated Temperatures

SSRN

引用

SSRN 2023年

作者： Sun, Hang Luo, Liang Yuan, Huan Li, Xi Key Lab of Structures Dynamic Behavior and Control The Ministry of Education Harbin Institute of Technology Harbin150090 China School of Transportation and Science Engineering Harbin Institute of Technology Harbin150090 China School of Civil Engineering Harbin Institute of Technology Harbin150090 China

This study explores the mechanical properties and microstructure of ultra-high-performance concrete with recycled aggregates (UHPC-RA) enhanced by nanosilica (NS) and steel fibers (SF) at elevated temperatures. Thirty-six mixtures, varying in RA replacement rates, SF, and NS content, were prepared and tested for compressive strength, splitting tensile strength, and elastic modulus. Microstructural analyses included SEM morphology, XRD composition, pore size distribution, thermal conductivity, and elemental distribution studies. Results show temperature-induced changes, including SF oxidation and spalling, causing brittle failures due to weakened cementitious matrix and ITZ bonding. Moisture evaporation and hydration product decomposition lead to mass loss. Compressive strength initially increases and then decreases with rising temperatures, while overall splitting tensile strength decreases. Deterioration in UHPC-RA's microstructure is main reason for macroscopic mechanical property degradation. Linear relationships between compressive and splitting tensile strength were established. SEM and XRD confirmed that NS particles contribute to the conversion of CH to C-S-H gels. © 2023, The Authors. All rights reserved.

关键词： Steel fibers

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Influence of Mix Proportioning Parameters and Curing Regimes on the Properties of Ultra-High Strength Alkali-Activated Concrete

SSRN

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SSRN 2023年

作者： He, Haiyu Zhang, Rong Song, Yuhuan Zhi, Xudong Fan, Feng Key Lab of Structures Dynamic Behaviour and Control The Ministry of Education Harbin Institute of Technology Harbin150090 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters The Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China

This study investigates the influence of mix proportioning parameters and curing regimes on the material properties of alkali-activated binder-based ultra-high strength concrete (AAB-UHSC). The effects of five groups of mix proportioning parameters (i.e., fly ash replacement ratio, silica fume replacement ratio, alkali to binder ratio, water glass modulus, and steel fiber content) and three curing regimes(i.e., ambient curing, standard curing, and hybrid curing) on the workability, compressive strength, flexural strength and microstructure development of AAB-UHSC were systematically evaluated. The results indicated that increasing the steel fiber and silica fume dosage negatively affected the flowability of freshly mixed AAB-UHSC. There existed an optimal alkali-to-binder ratio and water glass modulus in terms of flowability, compressive strength, and flexural strength, but the fly ash replacement ratio had a complex effect on the material performance of the AAB-UHSC. The microstructures of the specimens cured in hybrid curing regimes were denser, and fewer cracks were observed, which resulted in higher strength compared to specimens cured under ambient curing and standard curing conditions. The three types of curing regimes adopted barely alter the phases and molecular bonds of hydration products based on the XRD and FTIR results. In addition, the correlations between the compressive strength of the AAB-UHSC obtained under ambient curing conditions, standard curing conditions, and obtained under hybrid curing and standard curing conditions were analyzed, and the fitted results had higher correlation coefficients (R2). © 2023, The Authors. All rights reserved.

关键词： Compressive strength

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