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Fusion of structural damage identification results from different test scenarios and evaluation indices in structural health monitoring

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STRUCTURAL HEALTH MONITORING-AN INTERNATIONAL JOURNAL 2021年第5期20卷 2540-2565页

作者： Li, X. Y. Lin, S. J. Law, S. S. Lin, Y. Z. Lin, J. F. Jinan Univ Sch Mech & Bldg Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China Jinan Univ Sch Mech & Bldg Engn Guangzhou Peoples R China Chongqing Univ Sch Civil Engn Chongqing Peoples R China Shenzhen Acad Disaster Prevent & Reduct China Earthquake Adm Ctr Safety Monitoring Engn Struct Shenzhen 518003 Peoples R China

There are many existing algorithms and damage indices that can effectively meet the engineering need in damage diagnosis. However, all of them (except those with an exact formulation) are based on certain assumptions with approximations, and their performances depend on the combination of test parameters, for example, type, number, and location of excitations and sensors;identification algorithm adopted;and environmental noise effect. Results obtained from different combinations of these test parameters are different and they may be mathematically biased or contradicting. Existing practice adopts the general indication of result for further maintenance decisions or by subjective screening the results with engineering sense. This article demonstrates the possibility to have a better design of the structural health monitoring system where the benefits of different damage indices and evaluation methodologies can be reaped via the fusion of the identified results. The scenario for discussion is the vibration-based damage localization problem. The change in mode shape in the modal domain and change in the covariance of impulse response function change in the time domain are selected as damage indices for the illustration. An exact form of the covariance of impulse response function is also proposed for this purpose. The demonstration is conducted via a simulated truss structure, an experimental beam, and 280 days valid recorded data from an in-service suspension bridge deck. Different measurements are analyzed to produce large number of identified results for reducing traffic excitation effect, the temperature effect, and so on, and to enhance the structural damage information in the final set of results. Experiences in handling the structural health monitoring data for monitoring the movement of a structural joint before and after a typhoon are also presented. The proposed strategy does not need a mathematical model of the structure, but this leads to heavy sensor requi

关键词： Damage identification acceleration Bayesian fusion covariance mode shape structural health monitoring damage localization

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Ultra-high performance concrete reinforced with macro fibres recycled from waste GFRP composites

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CASE STUDIES IN CONSTRUCTION MATERIALS 2023年 18卷

作者： You, X. M. Lin, L. B. Fu, Bing Xiang, Yu 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 Hong Kong Polytech Univ Dept Civil & Environm Engn Hong Kong Peoples R China

Ultra-high-performance concrete (UHPC) is a promising cementitious composite to produce lightweight and high-performance structures. Steel fibres are an essential constituting material of UHPC to prevent the brittle failure of UHPC, but the high cost steel fibres impedes the wider application of UHPC to some extent. This paper proposes a concept to produce UHPC reinforced with macro fibres processed from waste glass-fibre-reinforced polymer (GFRP) composites, therefore addressing two issues of the high cost of UHPC as well as the difficulty in disposal of waste GFRP simultaneously. A series of tests have been carried out to investigate the effect of adding macro fibres on the properties of UHPC. The test results show that the incorporation of macro fibres leads to a loss of the workability and a reduction of up to 21.8 % in the compressive strength, but improves the flexural strength and flexural toughness greatly by up to 27.9 % and 46.9 times, respectively. The tensile constitutive relationship has been converted from the results of the bending tests through inverse analyses. The proposed concept of producing UHPC with recycled macro fibres contributes to lowering the price of UHPC, whose properties are compa-rable to that of UHPC with steel fibres, and establishing an effective routine to valorise the waste GFRP.

关键词： Ultra -high-performance concrete (UHPC) GFRP waste Mechanical recycling Fibre -reinforced concrete Macro fibres

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A Multi-State Strategy for Structural Damage Detection Using Sensitivity of Weighted Transmissibility Function

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INTERNATIONAL JOURNAL OF STRUCTURAL STABILITY AND DYNAMICS 2021年第10期21卷

作者： Luo, Ziwei Liu, Huanlin Yu, Ling Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

In practice, a model-based structural damage detection (SDD) method is helpful for locating and quantifying damages with the aid of reasonable finite element (FE) model. However, only limited information in single or two structural states is often used for model updating in existing studies, which is not reasonable enough to represent real structures. Meanwhile, as an output-only damage indicator, transmissibility function (TF) is proven to be effective for SDD, but it is not sensitive enough to change in structural parameters. Therefore, a multi-state strategy based on weighted TF (WTF) is proposed to improve sensitivity of TF to change in parameters and in order to further obtain a more reasonable FE model for SDD in this study. First, WTF is defined by TF weighted with element stiffness matrix, and relationships between WTFs and change in structural parameters are established based on sensitivity analysis. Then, a multi-state strategy is proposed to obtain multiple structural states, which is used to reasonably update the FE model and detect structural damages. Meanwhile, due to fabrication errors, a two-stage scheme is adopted to reduce the global and local discrepancy between the real structure and the FE model. Further, the l(1)-norm and the l(1/2)-norm regularization techniques are, respectively, introduced for both model updating and SDD problems by considering the characteristics of problems. Finally, the effectiveness of the proposed method is verified by a simply supported beam in numerical simulations and a six-storey frame in laboratory. From the simulation results, it can be seen that the sensitivity to structural damages can be improved by the definition of WTF. For the experimental studies, compared with the FE model updated from the single structural state, the FE model obtained by the multi-state strategy has an ability to more reasonably describe the change of states in the frame. Moreover, for the given structural damages, the proposed method can

关键词： Structural damage detection (SDD) model updating transmissibility function (TF) multi-state strategy regularization techniques

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A size-dependent model for shear deformable laminated micro-nano plates based on couple stress theory

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COMPOSITE STRUCTURES 2021年 259卷 113457-113457页

作者： He, Zanhang Xue, Jianghong Yao, Sishi Wu, Yongfu Xia, Fei Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

In this paper, a modified first order shear deformation theory is proposed for laminated micro-nano plates. Couple stress components are involved in the differential equations of equilibrium for shear deformable micro-nano plates, which are established by considering the deformation mechanism of an element cut from the micro-nano plate. Based on the mechanics of composite materials and Koiter's theory, the constitutive equations for laminated micro-nano plates are established to characterize the relationships between Cauchy stress tensor and the strain tensor, the couple-stress tensor and the curvature tensor. Governing equations with size-dependent effect are derived and are expressed in terms of the displacements and the rotation functions. The proposed theory is applied to investigate the eigenvalue buckling and free vibration of laminated micronano plates simply supported at the four sides. Matlab program based on the analytical solutions is developed and is testified by comparing the solutions for isotropic micro-nano plates from the proposed theory against those from an available model and from ABAQUS analysis. Various examples are studied to investigate the influence of scale ratio, aspect ratio, length-to-thickness ratio, material properties and stacking sequence on the buckling and free vibration response of the laminated micro-nano plates. The size-dependent effect is captured for all examples, particularly for micro-nano isotropic laminated plate with geometry size similar to its material length scale parameter, where the buckling load may be nearly up to 10 times larger than that given by the FSDT theory. A good agreement among solutions from the Matlab program, the existing literature and ABAQUS analysis demonstrates the efficiency and accuracy of the proposed theory.

关键词： Couple stress theory Scale effect Laminated micro-nano plates Shear deformation theory Buckling Free vibration

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A general continuum damage model for soft composites

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JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS 2023年第1期175卷

作者： Zhan, Lin Wang, Siyu Qu, Shaoxing Steinmann, Paul Xiao, Rui Zhejiang Univ Dept Engn Mech State Key Lab Fluid Power & Mechatron Syst Key Lab Soft Machines & Smart Devices Zhejiang Pro Hangzhou 310027 Peoples R China Jinan Univ Coll Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China Friedrich Alexander Univ Erlangen Nuremberg Inst Appl Mech Egerland Str 5 D-91058 Erlangen Germany

Soft composites, including filled rubbers, nanocomposite gels, double network hydrogels, and multiple network elastomers, all exhibit stress-softening behavior in loading-unloading cycles, also denoted as the Mullins effect. Though qualitatively this damage behavior shows similar features, the details still vary with material types. In this work, we provide a general approach towards modeling the Mullins effect for soft composites based on continuum damage mechanics. We start with formulating a one-dimensional damage model. A logarithmic damage variable is employed, while a damage potential function is adopted to obtain the evolution law for the damage variable. We then extend the one-dimensional damage model to three-dimensions. The eight-chain type micro-macro transition is used to formulate an isotropic damage model. An anisotropic damage model is constructed based on the full network model, while a new micro-macro mapping is used to determine the micro stretch from the macro deformation. With this new mapping, the full network model appears in a consistent format in that the free energy, dissipation, and stress are respectively given by the average of their directional micro counterparts. In the current approach, two constitutive functions need to be determined: the elastic free energy density and the stored energy limit. Simple forms of these two constitutive functions are provided with only a small set of model parameters. The resulting models are then successfully applied to describe the stress response in loading-unloading cycles and the anisotropic response of predeformed materials for different kinds of soft composites.

关键词： Mullins effect Continuum damage mechanics Micro-macro mapping Anisotropic damage model Soft composites

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A first order reliability method based on hybrid conjugate approach with adaptive Barzilai-Borwein steps

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COMPUTER METHODS IN APPLIED MECHANICS AND engineering 2022年第PartB期401卷 1页

作者： Wang, Xiaoping Zhao, Wei Chen, Yangyang Li, Xueyan Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China Guangzhou Univ Earthquake Engn Res & Test Ctr Guangzhou 510405 Peoples R China

In the first order reliability method (FORM), the Hasofer-Lind and Rackwitz-Flessler (HL-RF) algorithm sometimes encounters numerical instability problems due to the highly nonlinear limit state function (LSF). In this paper, an improved HL-RF algorithm introducing the hybrid conjugate gradient method with adaptive Barzilai-Borwein step sizes is developed to enhance the robustness and efficiency of the original HL-RF method. The proposed algorithm is composed of two stages, the steepest descent method is performed in the first stage to move to the vicinity of the most probable failure point (MPFP) and provide a good initial location for the second stage. Along with the hybrid conjugate search direction defined by the descent direction of the non-differential merit function, the second stage quantizes the adaptive Barzilai-Borwein step sizes to accelerate the process of locating the final MPFP under the nonmonotone line search rule. Eight illustrative examples with nonlinear LSFs are analyzed in detail to validate the performance of the proposed algorithm compared with other first order reliability methods. The results indicate that the proposed algorithm is not only computationally efficient but also robust in terms of convergence, especially for those problems with super nonlinear LSFs and with nonlinear LSFs involving high-frequency noise terms. (c) 2022 Elsevier B.V. All rights reserved.

关键词： First order reliability method Most probable failure point Reliability index Conjugate gradient method Barzilai-Borwein step size

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Weighted Transmissibility Assurance Criterion for Structural Damage Detection

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JOURNAL OF AEROSPACE engineering 2021年第3期34卷 04021016-04021016页

作者： Luo, Ziwei Liu, Huanlin Yu, Ling Jinan Univ Sch Mech & Construct Engn Minist Educ Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

Transmissibility function (TF) is a useful damage indicator for effective structural damage detection (SDD) under unknown external excitations. However, TF is not sensitive enough to structural damage under measurement noise. To improve the sensitivity of this indicator, a common model reduction technique, that is, the system equivalent reduction expansion process (SEREP) was first adopted to obtain reduced element stiffness matrices in the initial analytical finite-element model of a structure;this was used to weight the TFs in this study. Then, inspired by the cosine similarity measure, a novel damage indicator, called the weighted transmissibility assurance criterion (WTAC), was proposed for evaluating structural states. The effectiveness of the proposed damage indicator, WTAC, was first studied by a six-story frame in numerical simulations. The results showed that the TF weighted by the reduced element stiffness matrices improved the signal-to-noise ratio of the TF, and the proposed WTAC detected changes in structural states under noise. Moreover, further experimental studies on an aluminum alloy frame were conducted in order to assess the proposed WTAC. The results indicated that the proposed WTAC may provide a potential tool for effective SDD with strong robustness and stability for long-term monitoring on site.

关键词： Structural damage detection (SDD) Transmissibility function (TF) Damage indicator Output-only method Cosine similarity measure

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Probabilistic Prediction of Post-Earthquake Rubble Risk Distribution Range for Bottom Frame Structures

SSRN

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SSRN 2024年

作者： He, Yuhan Zhai, Changhai Wen, Weiping Key Lab of Structures Dynamic Behavior and Control The Ministry of Education Harbin Institute of Technology Harbin150090 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disaster The Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China

The rubble generated by the massive collapse of street-front buildings after an earthquake can seriously block roads, affecting the connectivity of the road network in a city and causing serious damage. In order to achieve the needs of urban planning, buildings facing the street are mainly bottom frame structures that cater for both commercial and residential use. However, once an earthquake occurs, the poor seismic performance of the bottom frame structures is quite prone to collapse, which produces a large amount of rubble and brings a great burden to the post-earthquake traffic system. In this paper, based on finite element models for various cases, considering the uncertainty of seismic intensity and height of the bottom frame structure, and combining with the fragility of structural collapse, we propose a method to predict the risk range of the bottom frame structure rubble to quantify the capacity of the transportation system after the earthquake, which can better assess the seismic resilience of the transportation system in the urban area. © 2024, The Authors. All rights reserved.

关键词： Earthquakes

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Random vibration fatigue curve and accelerated vibration test technology of transport package

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Zhendong Gongcheng Xuebao/Journal of Vibration engineering 2022年第2期35卷 297-306页

作者： Wang, Zhi-Wei Liu, Bo Wang, Li-Jun Packaging Engineering Institute Jinan University Zhuhai519070 China MOE Key Laboratory of Disaster Forecast and Control in Engineering Jinan University Guangzhou510632 China Key Laboratory of Product Packaging and Logistics of Guangdong Higher Education Institutes Jinan University Zhuhai519070 China Zhuhai Key Laboratory of Product Packaging and Logistics Jinan University Zhuhai519070 China

In this paper, the relation between the von Mises equivalent stress at the concerned point and the root mean square of the excitation acceleration on the transport package under triaxial random vibration excitation is derived. The equivalence between the stress fatigue curve (σ-N curve) at the concerned point and the vibration fatigue curve (Grms-T curve) of the transport package is certificated. For the two types of damage and fatigue models commonly used in engineering, that is, the Basquin type (power function type) and the exponential function, the corresponding Grms-T equations are obtained. The time compression ratio of accelerated random vibration test for transport package is given based on the Grms-T curve, and its validity is verified by the finite element analysis of product model. As the acceleration is easy to analysis and measurement, the accelerated random vibration test technology for transport package based on the Grms-T curve has application and development potential for further researches. © 2022, Editorial Board of Journal of Vibration engineering. All right reserved.

关键词： Exponential functions

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Bond behavior between recycled macro fibers and ultra-high-performance concrete matrix: Tests and property characterization

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JOURNAL OF BUILDING engineering 2024年 95卷

作者： You, X. M. Xu, Y. B. Fan, Y. C. Zou, Q. Q. Fu, Bing Jinan Univ Sch Mech & Construct Engn Guangzhou 510632 Peoples R China Harbin Inst Technol Sch Astronaut Harbin 150001 Peoples R China Southern Univ Sci & Technol Dept Ocean Sci & Engn Shenzhen 518055 Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

A green and cost-efficient ultra-high-performance concrete (UHPC) has been proposed using discrete macro fibers recycled from waste glass fiber reinforced polymer (GFRP). The tensile properties of such composites are significantly affected by the macro fiber/UHPC bond properties. However, there is very little work characterizing the bond properties of the macro fiber/UHPC interface. Furthermore. lack of study focused on the methods for macro fiber surface treatment and their effects on macro fiber/UHPC interfacial bonding. Therefore, the present study first carried out pullout tests in two series consisting of 128 pullout specimens. Series 1 aimed to characterize the bond behavior of the macro fiber/UHPC interface, while Series 2 aimed to investigate the effect of surface-modifying agents on macro fiber/UHPC interfacial bonding. The results demonstrated that the bond strength increased from 19.3 to 20.9 MPa when the embedded length of the 8 mm-wide fiber increased from 5 to 10 mm. The modification of neutral Nano SiO2 (NNS) enhanced the bond strength by up to 20.5 %, while alkaline Nano SiO2 (ANS) and silane coupling agent (SCA) showed a negative effect on bond strength. Then, the shear-lag theory was utilized for predicting the pull force-slip curves of the fibers embedded in UHPC, and then the bond parameters of the interfaces were obtained through an inverse analysis. A good agreement is exhibited with integral absolute error (IAE) from 4.5 % to 10.5 % between predicted results and test results.

关键词： Glass fiber reinforced polymer composites Ultra -high -performance concrete Recycling Macro fibers Interfacial bond

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