Shear-type structures are common structural forms in industrial and civil buildings,such as concrete and steel frame structures.Fault diagnosis of shear-type structures is an important topic to ensure the normal use o...Shear-type structures are common structural forms in industrial and civil buildings,such as concrete and steel frame structures.Fault diagnosis of shear-type structures is an important topic to ensure the normal use of structures.The main drawback of existing damage assessment methods is that they require accurate structural finite element models for damage assessment.However,for many shear-type structures,it is difficult to obtain accurate FEM.In order to avoid finite elementmodeling,amodel-freemethod for diagnosing shear structure defects is developed in this paper.This method only needs to measure a few low-order vibration modes of the structure.The proposed defect diagnosis method is divided into two stages.In the first stage,the location of defects in the structure is determined based on the difference between the virtual displacements derived from the dynamic flexibility matrices before and after damage.In the second stage,damage severity is evaluated based on an improved frequency sensitivity equation.Themain innovations of this method lie in two aspects.The first innovation is the development of a virtual displacement difference method for determining the location of damage in the shear structure.The second is to improve the existing frequency sensitivity equation to calculate the damage degree without constructing the finite elementmodel.Thismethod has been verified on a numerical example of a 22-story shear frame structure and an experimental example of a three-story steel shear structure.Based on numerical analysis and experimental data validation,it is shown that this method only needs to use the low-order modes of structural vibration to diagnose the defect location and damage degree,and does not require finite element modeling.The proposed method should be a very simple and practical defect diagnosis technique in engineering practice.展开更多
In this study,a static shear energy algorithm is presented for the damage assessment of beam-like structures.According to the energy release principle,the strain energy of a damaged element suddenly changes when struc...In this study,a static shear energy algorithm is presented for the damage assessment of beam-like structures.According to the energy release principle,the strain energy of a damaged element suddenly changes when structural damage occurs.Therefore,the change in the static shear energy is employed to determine the damage locations in beam-like structures.The static shear energy is derived from the spectral factorization of the elementary stiffness matrix and structural deflection variation.The advantage of using shear energy as opposed to total energy is that only a few deflection data points of the beam structure are required during the process of damage identification.Another advantage of the proposed approach is that damage detection can be performed without establishing a structural finiteelement model in advance.The proposed technique is first validated using a numerical example with single,multiple,and adjacent damage scenarios.A channel steel beam and rectangular concrete beam are employed as experimental cases to further verify the proposed approach.The results of the simulation and experiment examples indicate that the proposed algorithm provides a simple and effective method for defect localization in beam-like structures.展开更多
基金the Zhejiang Public Welfare Technology Application Research Project(LGF22E080021)Ningbo Natural Science Foundation Project(202003N4169)+2 种基金Natural Science Foundation of China(11202138,52008215)the Natural Science Foundation of Zhejiang Province,China(LQ20E080013)the Major Special Science and Technology Project(2019B10076)of“Ningbo Science and Technology Innovation 2025”.
文摘Shear-type structures are common structural forms in industrial and civil buildings,such as concrete and steel frame structures.Fault diagnosis of shear-type structures is an important topic to ensure the normal use of structures.The main drawback of existing damage assessment methods is that they require accurate structural finite element models for damage assessment.However,for many shear-type structures,it is difficult to obtain accurate FEM.In order to avoid finite elementmodeling,amodel-freemethod for diagnosing shear structure defects is developed in this paper.This method only needs to measure a few low-order vibration modes of the structure.The proposed defect diagnosis method is divided into two stages.In the first stage,the location of defects in the structure is determined based on the difference between the virtual displacements derived from the dynamic flexibility matrices before and after damage.In the second stage,damage severity is evaluated based on an improved frequency sensitivity equation.Themain innovations of this method lie in two aspects.The first innovation is the development of a virtual displacement difference method for determining the location of damage in the shear structure.The second is to improve the existing frequency sensitivity equation to calculate the damage degree without constructing the finite elementmodel.Thismethod has been verified on a numerical example of a 22-story shear frame structure and an experimental example of a three-story steel shear structure.Based on numerical analysis and experimental data validation,it is shown that this method only needs to use the low-order modes of structural vibration to diagnose the defect location and damage degree,and does not require finite element modeling.The proposed method should be a very simple and practical defect diagnosis technique in engineering practice.
基金supported by the National Natural Science Foundation of Zhejiang Province,China(No.LQ20E080013)the Natural Science Foundation of China(Grant No.52008215)+1 种基金the Major Special Science and Technology Project(No.2019B10076)“Ningbo Science and Technology Innovation 2025”and Ningbo Natural Science Foundation Project(No.202003N4169).
文摘In this study,a static shear energy algorithm is presented for the damage assessment of beam-like structures.According to the energy release principle,the strain energy of a damaged element suddenly changes when structural damage occurs.Therefore,the change in the static shear energy is employed to determine the damage locations in beam-like structures.The static shear energy is derived from the spectral factorization of the elementary stiffness matrix and structural deflection variation.The advantage of using shear energy as opposed to total energy is that only a few deflection data points of the beam structure are required during the process of damage identification.Another advantage of the proposed approach is that damage detection can be performed without establishing a structural finiteelement model in advance.The proposed technique is first validated using a numerical example with single,multiple,and adjacent damage scenarios.A channel steel beam and rectangular concrete beam are employed as experimental cases to further verify the proposed approach.The results of the simulation and experiment examples indicate that the proposed algorithm provides a simple and effective method for defect localization in beam-like structures.