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Structural Nonlinear Damage Identification Algorithm Based on Time Series ARMA/GARCH Model

ADVANCES IN STRUCTURAL engineering 2013年第9期16卷 1597-1609页

作者： Chen, Liu-jie Yu, Ling Jinan Univ Dept Mech & Civil Engn Guangzhou 510632 Guangdong Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China Sun Yat Sen Univ Sch Engn Guangzhou 510006 Guangdong Peoples R China

In recent years, vibration based structural damage detection has been paid more and more attention by many researchers, especially for those based on the time series analysis. However, the traditional methods are mainly based on the linear time series analysis, which cannot deal with nonlinear damages effectively, such as the fatigue cracks that open and close upon dynamic loading. A new algorithm for the nonlinear damage detection is proposed based on a model of autoregressive moving average (ARMA) with generalized autoregressive conditional heteroscedasticity (GARCH) (ARMA/GARCH) in this paper. First, a reference ARMA model is constructed with the acceleration responses measured in a reference (healthy) state and the one-step-ahead error prediction are modeled as a GARCH model. Secondly, the new nonlinear damage-sensitive feature (DSF) is defined as the conditional standard deviation of the residual error of GARCH model in the reference and the unknown states, respectively. The performance of the presented algorithm is then evaluated by the experimental data of a three-story building structure provided by Los Alamos National laboratory (LANL). Finally, the new algorithm is compared with the traditional methods based on the standard deviation ratio of the residual error of ARMA model. The illustrated results show that the proposed method can effectively estimate the extent of the nonlinear damage with higher accuracy. It has less computational cost and more robustness against operational and environmental variety. This makes it applicable for structural health monitoring in situ.

关键词： structural health monitoring nonlinear damage detection time series analysis ARMA/GARCH model

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Analysis of reinforced slope based on interface properties of geosynthetics and soil

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Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical engineering 2013年第SUPPL.2期35卷 217-223页

作者： Liu, Dong Chen, Xiao-Ping Chang, Xue-Ning College of Science and Engineering Jinan University Guangzhou 510632 China Key Laboratory of Disaster Forecast and Control in Engineering Jinan University Guangzhou 510632 China Guangdong Hydropower Planning and Design Institute Guangzhou 510170 China

As the geosynthetics are widely used in engineering practice to strengthen the slope stability, the interaction behaviors of geosynthetics and soil are very important for the slope stability analysis. A reinforced seawall constructed in coast reclamation project in Guangdong Province is analyzed. The interface friction properties of reinforcing materials and filling sand are studied by means of the laboratory shear tests and theoretical analyses, and the reinforcement mechanism is discussed. The numerical calculation is carried out on the stability and deformation behaviors of the reinforced slope under geostatic pressure. The test results show that the shear stress-shear displacement relationship of geosynthetics-soil interface is strain-harding. It is important for the stability of slope in soft foudation. In addition, the density of filling sand is the key factor for the frictional characteristics of interface. The stability analysis shows that the pavement method of reinforcing materials will directly affect the factor of safety of slope stability, and multilayer pavement effect is not a simple addition for every layer. Based on the circular slip surface method, the calculated factor of safety may be too small to reflect the contribution of geosynthetics, the strength reduction method is more reasonable for considering the interface friction. The finite element analysis also reveals that the effect of reinforcement on deformation behaviors of slope is mainly in the restriction to the magnitude of lateral deformation.

关键词： Shear stress

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An Alignment control Method of Continuous Beam Bridge

An Alignment Control Method of Continuous Beam Bridge

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2nd International Conference on Civil, Architectural and Hydraulic engineering (ICCAHE 2013)

作者： Liu, ZhiFeng Liu, YuXiang Xia, Yan Minist Educ China Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China Jinan Univ Dept Mech & Civil Engn Guangzhou 510632 Guangdong Peoples R China Jinan Univ Dept Mech & Civil Engn Guangzhou 510632 Peoples R China

ISBN: (纸本)9783037858578

By directing at the current situation of excessive midspan deflection in prestressed concrete continuous bridge during the past few years, this paper raised a calculation method to elevate the pre-camber. Factors that affect bridge alignment after the bridge is completed were treated as uniform load, test data about the existing bridge were set as the basis, quartic polynomial function was adopted to fit the pre-camber of bridge under construction, and the following conclusions were gained through simulation analysis on the bridge: 1) During calculation for construction pre-camber, this method can overcome or weaken the situation of excessive midspan deflection when the bridge is at operation stage;2) It can reduce detail analysis on displacement caused by concrete creep and automobile load after the bridge is completed;3) Relevant parameters are introduced to calculate predicted value of midspan deflection and make calculation for empirical pre-camber more rigorous;4) Its feasibility has been verified through calculation to guarantee load carrying safety in bridge construction and operation process, so it has relatively high promotion and application values.

关键词： Alignment of continuous beam bridge Quartic polynomial function method Construction pre-camber

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Numerical simulation of the oblique crack in the pipes using a chaotic oscillator based on ultrasonic guided wave

Numerical simulation of the oblique crack in the pipes using...

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20th International Congress on Sound and Vibration 2013, ICSV 2013

作者： Yang, Fei Jing, Lin Zhang, Weiwei Lin, Rong Ma, Hongwei College of Science and Engineering Jinan University Guangzhou 510632 China Impact Mechanics Laboratory Department of Mechanical Engineering National University of Singapore Singapore 117576 Singapore Department of Mechanics Taiyuan University of Science and Technology Taiyuan 030024 China Moe Key Laboratory of Disaster Forecast and Control in Engineering Jinan University Guangzhou 510632 China

ISBN: (纸本)9781629931500

The ultrasonic longitudinal guided waves in oblique cracked pipes were investigated using finite element software LS-DYNA 3D in this paper. Based on the improved Duffing chaotic oscillator with substitution of (-x3+x5) for (-x+x3) of the non-linear restoring force item, a novel inspection method was proposed. Four kinds of defects with inclined angle of 15°, 30°, 45°and 90° were analyzed, respectively. Numerical results show that the proposed method could be used to inspect weaker guided waves, and the amplitude of echo increases with the decrease of the inclined angle. The results are worthy of engineering application in both extending guided waves detection range and increasing the sensitivity of detecting micro oblique crack.

关键词： Guided electromagnetic wave propagation

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Structural Nonlinear Damage Identification Algorithm Based on Time Series ARMA/GARCH Model

Structural Nonlinear Damage Identification Algorithm Based o...

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12th International Symposium on Structural engineering (ISSE-12)

关键词： structural health monitoring nonlinear damage detection time series analysis ARMA/GARCH model

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Damage Detection for Structures under Ambient Vibration via Covariance of Covariance Matrix and Consistent Regularization

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ADVANCES IN STRUCTURAL engineering 2013年第1期16卷 77-86页

作者： Li, Xueyan Wang, Lixin Law, S. S. Jinan Univ Minist Educ China Dept Mech & Civil Engn Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China Earthquake Adm Guangdong Prov Guangzhou 510070 Guangdong Peoples R China Hong Kong Polytech Univ Dept Civil & Struct Engn Kowloon Hong Kong Peoples R China

A consistent regularization technique is adopted for the inverse identification of local damages in a structure under ambient vibration. The consistent regularization method fully makes use of the information from results obtained in previous iteration steps. Some elements are identified as undamaged and others are updated with small incremental steps between iterations. The covariance of covariance matrix which are formed from the auto/cross-correlation function of acceleration responses of a structure under white noise ambient excitation are used for damage detection in this paper. The components of the covariance matrix are proved to be function of the modal parameters (modal frequency, mode shape and damping parameter) of the structure. The number of vibration modes of the structure associated with the components is only limited by the sampling frequency. A simply supported thirty-one bar plane truss structure and a seven-floor frame structure are studied where a multiple damage scenario with different noise levels are identified. Numerical results show that the consistent regularization method combined with covariance of covariance matrix is very effective in improving the results in the inverse problem with ill-condition phenomenon compared with the Tikhonov regularization.

关键词： damage detection ambient vibration consistent regularization model updating covariance of covariance

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The Experimental Study of Using Composite Polymer Fiber in Concrete

The Experimental Study of Using Composite Polymer Fiber in C...

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3rd International Conference on Chemical engineering and Advanced Materials (CEAM 2013)

作者： Fu Hao Ou Yang-dong Xu Wei-ting Kong Lin-jie Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China Jinan Univ Res Ctr Engn Mat & Struct Durabil Guangzhou 510632 Guangdong Peoples R China City Univ Hong Kong Dept Civil & Architectural Engn Kowloon Hong Kong Peoples R China

ISBN: (纸本)9783037858141

Using the cylinder to take 2L as sample from five equidistant azimuthally and the center point to weight. Wash away the cement slurry in sample thoroughly first. Put the rest into the container full with water and churn. Then, collect the suspended fiber using the square-hole sieve of 75 um aperture. Churn it as more as possible to make sure of collecting whole fiber in samples. Wash clear and dry under 105 +/- 5 Celsius degree to constant weight. After cooling to room temperature then weight them respectively and accurate to 0.01g. The dispersion performance will be qualified if the dispersion relative error between arithmetic average value of synthetic fiber content and theoretical calculated value is from -10% to 10%. The concrete test steps is as per "Cement Concrete and Mortar Synthetic Fiber GBT21120-2007". Slump, slump flow of all the fresh concrete were tested to determine the fresh properties of fiber reinforced concrete. The mixing proportions are listed in Table 1, All the strength tests were carried out following the Chinese standard GB/T 50081-2002. Resistance to chloride ion penetration was measured according to ASTM C1202 (Rapid determination of the Chloride Permeability of Concrete) at the curing age of 7d, 28 days using a proportion of the Phi 100mm x 50mm cylinders. The early crack resistance test is according to the fiber reinforced concrete testing standards CECS 13-2009. It can be concluded that the working performance of composite fiber concrete are better compared with the single mixed concrete. It is obvious that the spread degree is being larger as the increasing of cellulosic fiber based on the certain adulterate amount. Fiber incorporation has little influence on concrete 7 d, 28 d age compression strength. The 7d and 28d splitting tensile strength, flexural strength were enhanced by incorporation of fibers. The addition of fiber improved the resistance ability of 7d and 28d fiber concrete chloride penetration to a great extent. It improve

关键词： polypropylene fiber polyvinyl alcohol fiber cellulose fiber fiber concrete

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Damage Detection for Structures under Ambient Vibration via Covariance of Covariance Matrix and Consistent Regularization

Damage Detection for Structures under Ambient Vibration via ...

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14th Asia Pacific Vibration Conference (APVC) on Dynamics for Sustainable engineering

关键词： damage detection ambient vibration consistent regularization model updating covariance of covariance

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Structural Damage Detection in a Truss Bridge Model Using Fuzzy Clustering and Measured FRF Data Reduced by Principal Component Projection

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ADVANCES IN STRUCTURAL engineering 2013年第1期16卷 207-217页

作者： Yu, Ling Zhu, Jun-hua Yu, Li-li Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China Minist Ind & Informat Technol Elect Res Inst 5 Guangzhou 510610 Guangdong Peoples R China Jinan Univ Dept Mech & Civil Engn Guangzhou 510632 Guangdong Peoples R China Hebei Univ Technol Sch Mat Sci & Engn Tianjin 300130 Peoples R China

This study deals with vibration-based damage detection in a truss bridge model and suggests a novel methodology based on fuzzy clustering and measured frequency response function (FRF) data reduced by principal component projection. A six-bay truss bridge model is designed and fabricated in laboratory, various connection damages are simulated by loosening the end connecter bolts, and the environmental effects are taken into account by changing in excitation force levels of a shaker. The FRFs of the healthy and the damaged structure are used as initial data. The FRF data normalization is performed for eliminating the effects caused by the environmental and operational variability. Two data projection algorithms, namely principal component analysis (PCA) and kernel principal component analysis (KPCA) are adopted for data compression and the median values of principal components are defined for damage feature extraction. The fuzzy c-means (FCM) clustering algorithm is used to categorize these features for structural damage detection. The illustrated results show that the proposed method can effectively identify the bridge damages simulated by loosening the bolted joints of the truss bridge structure. It is sensitive to the structural damage but it is non-sensitive to the effect of the environmental and operational variations. This makes it quite generic and permits its potential development for real and complex truss bridges in site.

关键词： structural health monitoring truss bridge structural damage detection eigenspace projections fuzzy clustering

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GREEN QUASIFUNCTION METHOD FOR FREE VIBRATION OF CLAMPED THIN PLATES

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Acta Mechanica Solida Sinica 2012年第1期25卷 37-45页

作者： Shanqing Li Hong Yuan MOE Key Laboratory of Disaster Forecast and Control in Engineering Institute of Applied MechanicsJinan UniversityGuangzhou 510632China

The Green quasifunction method is employed to solve the free vibration problem of clamped thin plates.A Green quasifunction is established by using the fundamental solution and boundary equation of the *** function satisfies the homogeneous boundary condition of the *** mode shape differential equation of the free vibration problem of clamped thin plates is reduced to Fredholm integral equation of the second kind by Green *** of the kernel of integral equation is overcome by choosing a suitable form of the normalized boundary *** examples demonstrate the validity of the present *** with both the series solution and ANSYS finite-element solution shows fine *** present method is a novel and effective mathematical one.

关键词： Green function integral equation R-function clamped thin plates free vibration

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