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Experimental validation of a signal-based approach for structural earthquake damage detection using fractal dimension of time frequency feature

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Earthquake Engineering and Engineering Vibration 2014年第4期13卷 671-680页

作者： Tao Dongwang Mao Chenxi Zhang Dongyu Li Hui Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering Mechanics China Earthquake Administration Key Lab of Structures Dynamic Behavior and Control (Harbin Institute of Technology) Ministry of Education Center of Structural Monitoring and Control School of Civil Engineeing Harbin Institute of Technology

This article extends a signal-based approach formerly proposed by the authors, which utilizes the fractal dimension of time frequency feature （FDTFF） of displacements, for earthquake damage detection of moment resist frame （MRF）, and validates the approach with shaking table tests. The time frequency feature （TFF） of the relative displacement at measured story is defined as the real part of the coefficients of the analytical wavelet transform. The fractal dimension （FD） is to quantify the TFF within the fundamental frequency band using box counting method. It is verified that the FDTFFs at all stories of the linear MRF are identical with the help of static condensation method and modal superposition principle, while the FDTFFs at the stories with localized nonlinearities due to damage will be different from those at the stories without nonlinearities using the reverse-path methodology. By comparing the FDTFFs of displacements at measured stories in a structure, the damage-induced nonlinearity of the structure under strong ground motion can be detected and localized. Finally shaking table experiments on a 1：8 scale sixteen-story three-bay steel MRF with added frictional dampers, which generate local nonlinearities, are conducted to validate the approach.

关键词： earthquake damage detection time frequency feature fractal dimension signal-based shaking table test frictional damper

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Modeling of the effect of water ingress on the bond between carbon fiber – Epoxy resin with the molecular dynamics technique 8

Modeling of the effect of water ingress on the bond between ...

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8th International Conference on Fibre-Reinforced Polymer (FRP) Composites in Civil Engineering, CICE 2016

作者： Xiao, Yanrong Xian, Guijun Li, Hui Key Lab of Structural Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin150090 China Harbin150090 China

ISBN: (纸本)9789881448026

FRP (fiber reinforced polymer) has taken advantages of the fiber reinforcement and resin matrix, possessing excellent mechanical properties and corrosive resistances, even in harsh environments. The lack of the knowledge of the durability performances of FRPs in various environmental conditions and the related degradation mechanisms of FRPs leads to significantly conservative design. Water ingress plays a critical effect on the durability of FRP, due to susceptibility of the bond between the fibers and resin matrices. In the present paper, molecular dynamics technique was used to model the moisture effect on the fiber-resin bond. The bonding performances of the epoxy on carbon fibers under dry and wet conditions were simulated. Free energy profiles were calculated to quantify interfacial adhesion. As shown from the decline of binding free energy, the water ingress led to remarkable deterioration of the fiber bonding to the resin matrix. The study is expected to be helpful for both the development of durable FRPs, and to predict the service life of a FRP subjected to hydrothermal aging accurately. Copyright © 2016 Department of Civil and Environmental Engineering & Research Institute for Sustainable Urban Development, The Hong Kong Polytechnic University.

关键词： Molecular dynamics

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Comparjsion of seismic performance of rc precast fabricated shear wall with different infillled opening

Comparjsion of seismic performance of rc precast fabricated ...

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2015 fib Symposium: Concrete - Innovation and Design

作者： Zhai, Ximei Hu, Wenbo Key Lab. of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin Heilongjiang150090 China

A new method to infill the opening in the RC precast fabricated concrete shear wall was applied in China. In this paper, three geometrically identical RC precast fabricated shear wall specimens were experimented under constant axial load and quasi-statie cyclic lateral loading. The methods to infill the opening of the wall were respectively integration infill, masonry infill and without infill. Hysteretic curves, skeleton curves, failure process, variation of rebar strain, stiffness, ductility and energy-dissipating capacity were obtained. The results showed that the integration shear wall owns good seismic performance. Its bearing capacity, stiffness, energy-dissipating capacity are excellent while ductility is relatively poor. Masonry infilled wall and wall without infill also own good seismic performance. Meanwhile, numerical simulation of three specimens was conducted by using finite element (FE) software OpenSees. Based on the reasonable modeling and the application of multi-layer shell element, the FE results were verified with the experimental results.

关键词： Shear walls

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Axial compression performances of concrete filled flax-basalt hybrid fibers reinforced FRP tubes 12

Axial compression performances of concrete filled flax-basal...

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Joint Conference of the 12th International Symposium on Fiber Reinforced Polymers for Reinforced Concrete Structures, FRPRCS 2015 and the 5th Asia-Pacific Conference on Fiber Reinforced Polymers in Structures, APFIS 2015

作者： Xia, Yuanyuan Xian, Guijun Li, Hui Key Lab. of Structural Dynamic Behavior and Control Harbin Institute of Technology Ministry of Education Harbin150090 China School of Civil Engineering Harbin Institute of Technology Harbin150090 China

Flax fiber reinforced polymer (FFRP) composites could be used in civil engineering as structural materials. To improve the mechanical properties and durability of FFRP, flax-basalt hybrid fiber reinforced polymer (HFRP) composite was developed. In the present study, unidirectional HFRP tubes were prepared with a winding process, and the compression performances of the concrete filled HFRP tubes were investigated. HFRP coupon was prepared and tested in tensile properties. The tensile results of the HFRP plate coupons shows linear in stress-strain, and hybrid with basalt fiber enhances the elongation at break remarkably. The tensile strength and modulus of the HFRP follow the rule of mixture. The concrete filled HFRP tubes exhibited much improved ultimate strength and ductility compared to those with the flax fiber tubes. The axial compression stress-strain curves were analyzed with the existing models. The coefficients of confinement of HFRP were higher than those of glass or carbon fiber based FRPs. © APFIS 2015. All rights reserved.

关键词： Fiber reinforced plastics

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Effect of glass fiber fabrics isolation layer on the adhesion bond behaviours between CFRP plates and steel substrates 12

Effect of glass fiber fabrics isolation layer on the adhesio...

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作者： He, Jun Xian, Guijun Li, Hui Key Lab. of Structural Dynamic Behavior and Control Harbin Institute of Technology Ministry of Education Heilongjiang Harbin150090 China School of Civil Engineering Harbin Institute of Technology Heilongjiang Harbin150090 China

Strengthening of steel structures with adhesively bonded carbon fiber-reinforced polymer (CFRP) plates has received extensive attentions in recent years. Since galvanic corrosion occurs between CFRP and the steel, glass fiber fabrics (GFF) are generally applied as an isolation layer. The present paper studied the effects of GFF on the bonding performances (such as ultimate strength and bond-slip relationship) between the CFRP and steel substrates. A series of pull-off tests were performed with variables of the thickness of the GFF layer. The testing results shows that the failure mode is the CFRP plate delamination failure, rather than cohesive failure. Based on this failure mode, the bondslip relationship curves is also trapezoidal shape for ductile adhesive and the thickness of the GFF isolation layer has no influence on the bonding performances. © APFIS 2015. All rights reserved.

关键词： Plates (structural components)

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Investigation on mapping relationship between deflection and cable tension by artificial neural networks 11

Investigation on mapping relationship between deflection and...

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11th International Workshop on structural Health Monitoring 2017: Real-Time Material State Awareness and Data-Driven Safety Assurance, IWSHM 2017

作者： Tian, Yadi Li, Hui Key Laboratory of Intelligent Disaster Prevention and Mitigation for Civil Infrastructure Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters Ministry of Industry and Information Technology Key Laboratory of Structural Dynamic Behavior and Control School of Civil Engineering Harbin Institute of Technology Harbin150090 China

ISBN: (纸本)9781605953304

Cables usually serve as critical load-bearing structural components in cable-stayed bridges. Vertical deflection is an important overall indicator that directly reflects the health status of bridge. The relationship between cable tension and vertical deflection also reflects the underlying mechanism of structures. In this context, a machine learning-based approach is proposed. Cable tension and vertical deflection are caused by prestress, temperature and vehicle loads. In this study, we focus on the cable force and vertical deflection caused by vehicle loads. Artificial neural network (ANN) is employed as the supervised learning method to learn the relationship between cable tension and vertical deflection. Field monitored data of Jintang Bridge are used to test the validity of the proposed method. The results show that ANN is capable of modelling vertical deflection from cable tension data in the case of arbitrary vehicle distribution. The proposed method which integrates the local and global variables by using two different kinds of monitoring data, avoids the complicated mechanical derivations, and is proved to be environment-insensitive.

关键词： Neural networks

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Ultrasonic guided waves sensing using optical fiber sensor 7

Ultrasonic guided waves sensing using optical fiber sensor

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7th International Conference on structural Health Monitoring of Intelligent Infrastructure, SHMII 2015

作者： Zhou, W. Li, H. Dong, Y. Wang, A. 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 National Key Laboratory of Science and Technology on Tunable Laser Harbin Institute of Technology Harbin150001 China

Optical fiber sensors have been proven that they have potential as ultrasonic guided waves sensor for structural health monitoring and damage detection. They can be used to receive acoustic emission signals from dynamic structural damages or guided waves propagating in waveguide and excited by ultrasonic actuators. Optical fiber sensors based on Mach-Zehnder interferometer were investigated in this work. Their sensing properties were explored experimentally using Lamb waves excited by a piezoelectric wafer in an aluminum plate. Spiral shape with different size was selected to increase their sensitivity. Experiments were also conducted to examine the voltage responses received by this type of sensor, and investigate results of tuning frequency. © 2015, International Society for structural Health Monitoring of Intelligent Infrastructure, ISHMII. All rights reserved.

关键词： structural health monitoring

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Bond behavior between basalt fiber reinforced polymer sheet and concrete substrate: Effects of elevated temperatures and sustained load 12

Bond behavior between basalt fiber reinforced polymer sheet ...

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作者： Lu, Zhongyu Xian, Guijun Li, Hui Ueda, Tamon 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 Division of Engineering and Policy for Sustainable Environment Faculty of Engineering Hokkaido University Kita 13 Jo Nishi 8 Chome Kita-ku Sapporo060-8628 Japan

This paper presents the effects of elevated temperatures and sustained load on the bond behavior between basalt fiber reinforced polymer sheet and concrete substrate. Three test replicates were performed through a single lap shear bond test. The temperatures were ranging from room temperature to 60 °C with the interval of 10 °C, and the sustained load was set as 35% peak load of the control specimens. Specimens with sustained load were exposed to elevated temperatures up to 3 h, and the failure test was performed at the elevated temperatures. Sustained load at elevated temperatures shows a significant effect on the bonding behavior. The specimens exposed at 30, 40, 50 and 60 °C increased the peak load by 9.6%, 31.2%, 29.6% and 20.2%, respectively. It was recognized that the shear stress redistributed at the concrete-BFRP interfaces during the test. The failure mode changed from concrete cohesion to adhesive failure with the increase of the temperatures. The variation of the failure patterns is attributed to the softening of the adhesion bond at elevated temperatures. © APFIS 2015. All rights reserved.

关键词： Fibers

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Bayesian system identification based on hierarchical sparse Bayesian learning and gibbs sampling with application to structural damage assessment

arXiv

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arXiv 2017年

作者： Huang, Yong Beck, James L. Li, Hui Key Lab of Structural Dynamic Behavior and Control of the Ministry of Education School of Civil Engineering Harbin Institute of Technology Harbin China Division of Engineering and Applied Science California Institute of Technology CA United States

Bayesian system identification has attracted substantial interest in recent years for inferring structural models based on measured dynamic response from a structural dynamical system. The focus in this paper is Bayesian system identification based on noisy incomplete modal data where we can impose spatially-sparse stiffness changes when updating a structural model. To this end, based on a similar hierarchical sparse Bayesian learning model from our previous work, we propose two Gibbs sampling algorithms. The algorithms differ in their strategies to deal with the posterior uncertainty of the equation-error precision parameter, but both sample from the conditional posterior probability density functions (PDFs) for the structural stiffness parameters and system modal parameters. The effective dimension for the Gibbs sampling is low because iterative sampling is done from only three conditional posterior PDFs that correspond to three parameter groups, along with sampling of the equation-error precision parameter from another conditional posterior PDF in one of the algorithms where it is not integrated out as a "nuisance" parameter. A nice feature from a computational perspective is that it is not necessary to solve a nonlinear eigenvalue problem of a structural model. The effectiveness and robustness of the proposed algorithms are illustrated by applying them to the IASE-ASCE Phase II simulated and experimental benchmark studies. The goal is to use incomplete modal data identified before and after possible damage to detect and assess spatially-sparse stiffness reductions induced by any damage. Our past and current focus on meeting challenges arising from Bayesian inference of structural stiffness serve to strengthen the capability of vibration-based structural system identification but our methods also have much broader applicability for inverse problems in science and technology where system matrices are to be inferred from noisy partial information about their eigenq

关键词： Probability density function

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Numerical simulation on dynamic response of blast-resistance door with built-in aluminum matrix syntactic foam

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Binggong Xuebao/Acta Armamentarii 2014年 35卷 263-267页

作者： Zhang, Bo-Yi Zhai, Dong-Xian Sun, Jian Wang, Wei Key Lab. of Structures Dynamic Behavior and Control Harbin Institute of Technology HarbinHeilongjiang150090 China School of Civil Engineering Harbin Institute of Technology HarbinHeilongjiang150090 China

A novel anti-blast door protective structure with built-in aluminum matrix syntactic foam is designed, which takes advantage of the good energy absorption property of the porous metal material. In order to investigate the dynamic response properties of two type of steel anti-blast door and anti-blast door with built-in aluminum matrix syntactic foam, they are compared under the explosion load of the same TNT equivalent in terms of the effective stress at the central point of the front face, the displacement-time history of the center point of the back face and the energy distribution of the structure using the FE software LS-DYNA. Simulation shows that the anti-blast door with built-in aluminum matrix syntactic foam absorbs the energy generated by the compression effect of the shock wave through the core layer of composite aluminum foam. For the anti-blast door with aluminum matrix syntactic foam, the stress field distributes more uniformly, the peak stress of the front face is reduced by 35%, the maximum displacement of the back face is decreased by 50%, which effectively improves the load bearing capacity and the deformability of the structure subjected to the explosion shock waves. ©, 2014, China Ordnance Society. All right reserved.

关键词： dynamic response

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