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10th International Conference on Structural Health Monitoring of Intelligent Infrastructure, SHMII 2021

作者： Nie, Zhenhua Xie, Yongkang Ma, Hongwei College of Science & Engineering Jinan University Guangdong Guangzhou China The Key Laboratory of Disaster Forecast and Control in Engineering Guangdong Guangzhou China Dongguan University of Technology Dongguan China

Vibration response based damage detection methods have attracted much attention due to that they are model free methods. However, in the most of structural health monitoring systems, excessive number of sensors installed on the bridge bring high costs and huge data. In this paper, a novel damage detection method based on recursive principal component analysis (RPCA) is proposed. The displacement responses are collected and decomposed recursively to obtain the orthogonal projection deviation at each moment while the moving vehicle is passing through the bridge. When the moving vehicle passes the damage location, a significant change of projection deviation will occur due to the discontinuity of the responses, which can be used to indicate the damage location. Numerical simulations performed on a simply supported beam bridge subjected to a moving load demonstrate the effectiveness of the proposed approach. It is noticed that only two sensors without limitation of placement location are needed in this data-driven method while no reference data is required, which leads the presented approach to be a good candidate for baseline free structural health monitoring with very limited measurement information. © 2021 International Conference on Structural Health Monitoring of Intelligent Infrastructure: Transferring Research into Practice, SHMII. All rights reserved.

关键词： Damage detection

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Fracture characteristics and in-situ damage mechanism of PIP-C/SiC composites to various temperatures and loading velocities

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engineering FRACTURE MECHANICS 2023年第1期286卷

作者： Zhao, Guicheng Jiang, Zhonghe Qu, Zhaoliang Xi, Huifeng Ai, Shigang Beijing Inst Technol Inst Adv Struct Technol Beijing 100081 Peoples R China Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

C/SiC composites prepared by polymer infiltration and pyrolysis (PIP) are among the most promising materials for application in ultrahigh-temperature conditions. However, the mechan-ical properties and damage mechanisms of PIP-C/SiC composites at different loading velocities and temperatures have not been systematically studied. In this study, in-plane compression, bending, and in-plane shear experiments were systematically performed at different loading ve-locities and temperatures in an inert atmosphere. The ultimate strengths of the PIP-C/SiC com-posite were determined under different conditions, and the failure modes were revealed. In addition, in-situ X-ray microtomography tension experiments were conducted to study the failure mechanism of the PIP-C/SiC composite. The results showed that the ultimate strengths were considerably affected by the temperature and loading velocity, and the failure modes were dependent on experimental types. The fracture location of the PIP-C/SiC composite is affected by the defect. And the direction of crack propagation is toward the existing cracks and voids.

关键词： C SiC composites High temperature Mechanical properties In -situ tension Failure mechanism

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Vehicle weight identification based on equivalent loads reconstructed from responses of beam-like bridge

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JOURNAL OF SOUND AND VIBRATION 2022年 534卷

作者： Pan, Chudong Zhang, Liwen Ye, Xijun Sun, Zhuo Guangzhou Univ Sch Civil Engn Guangzhou Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China

Moving force identification (MFI) is an effective way for closely monitoring vehicle weight in a dynamic state. Time-varying position of vehicle is usually needed. This applying condition may limit the applicability because the measurement of time-varying position has certain difficulty. To tackle this problem, this study proposes an equivalent load-based method for identifying the gross weight of a vehicle moving on a beam-like bridge. The proposed method is developed based on an innovative concept of equivalent load and the application of force reconstruction. Herein, the equivalent loads are expressed as some concentrated loads whose acting positions are time invariant. Modal forces induced by the equivalent loads are equal to the ones caused by the vehicle-induced moving forces. Under the crucial assumption of equivalent loads, the first key step is to reconstruct the equivalent loads by using a force identification method that is imple-mented via matrix regularization. Since the equivalent loads have been estimated, the second step aims to introduce a practical strategy for identifying the vehicle weight from the sum of the identified equivalent loads rather than the sum of moving forces. Because of this, a highlight is that time-varying position of vehicle is not needed. To verify the effectiveness and feasibility of the proposed method, beam structures with single span are carried out for numerical simulations and experimental validations. Illustrated results show that the proposed method can be applied for identifying the gross weight of a vehicle moving on a beam-like bridge with high accuracy and strong robustness. Some related issues are discussed as well.

关键词： Vehicle weight identification Force reconstruction Equivalent load Matrix regularization Inverse problem

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Full Characterization of the Work-Hardening Behavior of Metals:An Accurate and Explicit Approach

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Acta Mechanica Solida Sinica 2020年第4期33卷 479-486页

作者： Zan Zhou Siyu Wang Lin Zhan Huifeng Xi Heng Xiao School of Mechanics and Construction Engineering and MOE Key Lab of Disaster Forecast and Control in Engineering Jinan UniversityGuangzhou 510632China Shanghai Institute of Applied Mathematics and Mechanics&School of Mechanics and Engineering Science Shanghai UniversityShanghai 200072China

A new approach is proposed to characterize the work-hardening behavior of metals based on the stress-strain data from uniaxial extension *** this new approach,the yield strength as a function of the plastic work can be determined by directly fitting a wellchosen single-variable shape function to any given uniaxial data from the initial yielding up to the strength limit,in an explicit sense with no need to carry out the usual tedious trial-and-error procedures in treating nonlinear elastoplastic rate equations toward identifying numerous unknown *** examples show that the simulation results with the new approach are in accurate agreement with the test data.

关键词： Metals Elastoplasticity Finite strain Work-hardening Yield strength Strength limit Explicit characterization

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Chaotic enhanced colliding bodies optimization algorithm for structural reliability analysis

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ADVANCES IN STRUCTURAL engineering 2020年第3期23卷 438-453页

作者： Cheng, Jiaming Zhao, Wei Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China

It is of extreme importance to assess the failure probability and safety level of structural system in structural design. Nowadays, many researchers presented several approaches for structural reliability analysis, such as the first-order reliability method, Monte Carlo simulation, and the meta-heuristic algorithm. The meta-heuristic algorithm is not only efficient to solve global optimization problems but also shown to be an effective tool for structural reliability analysis. A recent meta-heuristic optimization approach, enhanced colliding bodies optimization, has emerged as a relatively simple implementation with a fast convergence speed. Chaos theory is characterized by its ergodicity, pseudo-randomness, and irregularity. This article thus presents a novel approach introducing chaotic maps into the enhanced colliding bodies optimization algorithm to promote the performance of convergence, named as chaotic enhanced colliding bodies optimization algorithm. The proposed algorithm uses chaotic maps to change the generation pattern of particles and improve convergence characteristics. A procedure based on the effective use of the represented chaotic enhanced colliding bodies optimization is then applied in structural reliability analysis. A variety of numerical and structural problems are tested in this article to demonstrate that the given method actually improves the performance of enhanced colliding bodies optimization in convergence as well as the accuracy for reliability analysis compared with the other methods existing in the literature.

关键词： chaos enhanced colliding bodies optimization meta-heuristic algorithm optimization algorithm structural reliability

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Flexural performance of reinforced concrete beams strengthened using near-surface-mounted carbon-fiber-reinforced polymer bars: Effects of bonding patterns

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COMPOSITE STRUCTURES 2024年 335卷

作者： Lv, J. B. Lin, D. J. Fu, Bing Liu, S. H. Han, Z. J. Guangdong Univ Technol Sch Civil & Transportat Engn Guangzhou 510643 Peoples R China Jinan Univ Sch Mech & Construct Engn Guangzhou 510632 Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

The near-surface-mounted (NSM) fiber-reinforced polymer (FRP) technique is effective for enhancing the load carrying capacity of strengthened reinforced concrete (RC) beams. However, this technique significantly reduces the deformability of strengthened RC beams. To overcome this, the present study combines the NSM strengthening method with the partial bonding technique: the strengthening FRP reinforcement is partially bonded onto the concrete substrate). Six full-scale 4.3 m long RC beams strengthened with NSM FRPs using various bonding patterns were tested. The results indicated that mechanical interlocking grooves slightly improve the load carrying capacity, but have a negligible effect on the deformability of the strengthened beams. A decrease in the bond length increased deformability by 27.2 %, with only a 7.6 % drop in load capacity compared to that of the beam with full bonding. An advanced finite element model was developed and validated to confirm an optimal bond length of 930 mm for maximum flexural performance.

关键词： Fiber-reinforced polymer Flexural strengthening Reinforced concrete beams Near-surface-mounted Mechanical interlocking groove Partially bonded system

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Modal parameter extraction from improved principal component analysis and structural state identification

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ADVANCES IN STRUCTURAL engineering 2024年第14期27卷 2544-2565页

作者： Li, Xueyan Liu, E. Wang, Lixin Lin, S. J. Zhao, W. Jinan Univ Sch Mech & Bldg Engn MOE Key Lab Disaster Forecast & Control Engn 601 Huangpu Ave West Guangzhou 510632 Peoples R China Jinan Univ Sch Mech & Bldg Engn Guangzhou Peoples R China Shenzhen Acad Disaster Prevent & Reduct Ctr Safety Monitoring Engn Struct Shenzhen Peoples R China

With the vigorous development of building structures and important infrastructure, structural health monitoring is necessary. Because there is no need to establish structural finite element modeling and train for various structural conditions, the data-driven and unsupervised learning method is very popular. Principal component analysis is a powerful signal analysis tool, but its lack of physical significance and the loss of sensitive information have hindered its wider application. Therefore, the improved principal component analysis based narrowband filtering is proposed to extract mode shapes and construct the structural state vectors, so that the damage index is more sensitive to damage and robust to the environmental factors. After the vibration response of the long-term monitoring is analyzed by the principal component analysis, the Gaussian mixture model clustering analysis is used to classify the structural states. Finally, the proposed method is applied to the analysis of the simulation data of ASCE Benchmark structure and the measured data of steel beams in the lab. The results show that the structural state vector is sensitive to structural damage. The clustering analysis of Gaussian mixture model can distinguish the structural states. The effectiveness of the proposed method is verified.

关键词： structural damage identification narrowband filtering principal component analysis Gaussian mixture model cluster analysis

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High-efficiency algorithms for simulating metal failure effects under multiaxial repeated loadings

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INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN engineering 2022年第5期123卷 1277-1293页

作者： Zhan, Lin Wang, Si-Yu Bruhns, Otto T. Xiao, Heng Jinan Univ Sch Mech & Construct Engn West Huangpu Ave 601 Guangzhou 510632 Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn West Huangpu Ave 601 Guangzhou 510632 Peoples R China Zhejiang Univ Sch Aeronaut & Aerosp Engn Hangzhou Peoples R China Ruhr Univ Bochum Inst Mech D-44780 Bochum Germany

High-efficiency algorithms are proposed for numerically integrating elasto-plastic rate equations for the purpose of simulating metal failure effects under repeated loading conditions. Results are obtained with a newly established elasto-plasticity model which can automatically simulate both low and high cycle fatigue failure effects, with reference to neither damage-like variables nor ad hoc failure criteria. Novelties are incorporated in a few respects. First, multiaxial loading processes with arbitrarily changing principal stresses and axes can be treated in a broad sense beyond usually treated proportional loading cases. Second, by means of the commonly used J2-invariant of the deviatoric stress, multiaxial loading cases can be directly treated just as in the uniaxial loading case. Third, high cost in time consumption can be considerably reduced in evaluating both low and high cycle failure effects. Numerical examples are presented for simulating uniaxial and multiaxial fatigue failure effects and simulation results are in good agreement with experimental data. Results show that the computation speed with the new algorithms exceeds 600 times faster than usual integration algorithms.

关键词： metals fatigue failure elasto-plastic equations multiaxial repeated loading high-efficiency algorithms

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Study on the size effect of rock under dynamic direct tension and indirect tension

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ENVIRONMENTAL EARTH SCIENCES 2024年第1期83卷 14-14页

作者： Jia, Yu Zhai, Yue Liu, Shi Changan Univ Sch Geol Engn & Geomat Xian 710064 Shaanxi Peoples R China Jinan Univ Sch Mech & Construct Engn Key Lab Disaster Forecast & Control Engn Minist Educ China Guangzhou 510632 Peoples R China China Univ Min & Technol State Key Lab Geomech & Deep Underground Engn Xuzhou 221116 Jiangsu Peoples R China

To explore the size effect of dynamic tension on the mechanical properties of rocks, the phi 75mm SHTB and the phi 75mm SHPB test systems were used to test red sandstone samples with four different length-diameter ratios (l/d = 0.3, 0.5, 0.8, and 1.0). The size effect of fracture characteristics, tensile strength, and stress balance of rock samples under two loading methods were investigated, and two indexes that can characterize the size influence of rock's fracture mechanism were defined: the relative length fracture ratio eta L and the relative area fracture ratio eta S. The results show that: (1) in the direct tensile test, with the increase in l/d ratio, the eta L of samples constantly increases, which shows that the fracture plane is farther away from the incident bar. And samples of all sizes have direct tensile strengths between 2.3 and 3.1 MPa, which drop as the l/d ratio rises. (2) In the indirect tensile test, the eta S of samples increases with the increase in l/d ratio, which shows that the area of the triangle-like crushing area at both ends of the sample decreases. And the plastic stage of the stress-strain curve of the specimen decreases continuously, and the impact indirect tensile strength increases continuously with the increase in l/d ratio. (3) Under two different loading methods, the uniformity of the internal stress of samples decreases as the l/d ratio rises and the samples at 1.0 l/d ratio can hardly meet the requirements of stress balance. (4) Size effect and non-uniformity effect are the main reasons for the difference between dynamic direct and indirect tensile strength, and non-uniformity effect plays a leading role.

关键词： Rock mechanics Dynamic direct tension Size effect Large-diameter SHTB Red sandstone

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Pattern Matching-Based Structural Damage Identification Using Mode Shape Difference Ratio with Limited Sensors

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INTERNATIONAL JOURNAL OF STRUCTURAL STABILITY AND DYNAMICS 2023年第9期23卷 2350106-2350106页

作者： Xiang, Hong Nie, Zhenhua Gao, Ruofan Ma, Hongwei Jinan Univ Sch Mech & Construct Engn Guangzhou Peoples R China Minist Educ Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China Dongguan Univ Technol Sch Environm & Civil Engn Dongguan Peoples R China

In order to rapidly identify structural damage, a pattern matching-based structural damage identification using mode shape difference ratio with limited sensors is proposed. The mode shape difference ratio is proposed as the damage indicator for pattern matching. The natural frequencies and mode shapes of the structure under different damage scenarios are obtained by the numerical simulation with finite element software. Using the simulation results, the damage pattern library based on mode shape difference ratio matrix is constructed. Afterwards, for the real structure to be test, the response power spectrum ratio is calculated with the measured acceleration responses. Then the mode shape difference ratio matrix of real structure is constructed using the power spectrum ratio of the measured responses with limited sensors. With the reciprocal of correlation coefficient difference (ROCCD) used as the pattern matching approach, the actual structural damage pattern is matched with the pattern in the damage pattern library. The pattern in the library corresponding to the maximum value of ROCCD is considered to be the damage condition of the structure. Finally, the numerical simulation and experiment of a four-layer interlayer shear model are investigated. The results show that the proposed method well determines the damage location and severity of the structure, and possesses excellent practicability.

关键词： Damage identification pattern matching mode shape difference ratio limited sensors power spectrum ratio correlation coefficient

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