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Damage detection in bridges under moving loads based on subspace projection residuals

ADVANCES IN STRUCTURAL engineering 2022年第5期25卷 979-1001页

作者： Nie, Zhenhua Xie, Yongkang Li, Jun Hao, Hong Ma, Hongwei Jinan Univ Sch Mech & Construct Engn Guangzhou Guangdong Peoples R China Minist Educ China Key Lab Disaster Forecast & Control Engn Guangzhou Guangdong Peoples R China Curtin Univ Sch Civil & Mech Engn Ctr Infrastruct Monitoring & Protect Kent St Bentley WA Australia Dongguan Univ Technol Dongguan Peoples R China

This paper proposes a data-driven method using subspace projection residual of the responses to identify the damage locations in bridges subjected to moving loads. In this method, a moving window with a certain length determined by the sampling frequency and the fundamental frequency of the measured responses is used to cut out the acceleration responses of the bridge subjected to a moving vehicle. The characteristic subspaces of the windowed signals are subsequently extracted to calculate the local damage index using the subspace projection residual. When the window moves to the damage location, the orthogonality between the active subspace of the damaged state and the null subspace of the healthy state is invalid, which leads to a relatively large projection residual that can be used to localize the damage. To improve the reliability of the proposed approach, a one-side upper confidence limit is introduced. A simply supported beam bridge subjected to a moving mass is simulated to verify the effectiveness of the proposed method. Numerical results indicate that the proposed approach can accurately localize the single and multiple damages, even when the responses are smeared with a significant noise. Experimental tests conducted on a steel beam bridge model also demonstrate the performance and accuracy of the proposed approach. The results demonstrate that the proposed method can localize the damage even with a small number of sensors, indicating the method has a good and promising performance for practical engineering applications.

关键词： data-driven structural damage localization subspace projection residual moving loads limited number of sensors

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Damage evaluation of steel frame subjected to impact load at midspan

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ce/papers 2023年第3-4期6卷 1202-1206页

作者： Chen, Ying Chen, Wensu Hao, Hong Nie, Zhenhua Jinan University Guangzhou China The Key Laboratory of Disaster Forecast and Control in Engineering Guangzhou China Curtin University Curtin Australia Guangzhou University Guangzhou China

The lower floors of the multi-storey structure can be impacted by the debris from the upper floor caused by gas and bomb explosion, which may induce damage or failure of the impacted substructure and lead to progressive collapse of large-scale structure. The behavior of the frame with a steel beam and two adjacent beam-column joints was numerically analyzed when the beam was impacted at midspan by various combinations of impact mass and velocity. The failure mode of the joints, the impact load and midspan displacement were analyzed. It shows that the beam-column joint fails prior to the beam under all impact loading scenarios. The residual bearing capacity of the frame was also studied by statically pushing-down the substructure after impact loading. A damage index was proposed using the residual capacity of the frame after impact loading divided by the static capacity of the joint without impact loading, and four damage levels, i.e., the minor damage, medium damage, severe damage, and collapse, were defined by the damage index. The boundaries of different damage levels of the frame under various impact loads were fitted, and it can be used to evaluate the damage level of the frame subjected to possible impact loads. © 2023 Ernst & Sohn GmbH.

关键词： Floors

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A numerical analysis of sloshing dynamics of two-layer liquid with a free surface

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OCEAN engineering 2023年第1期268卷

作者： Cao, Weinan Li, Xiaoming Gao, Ying Li, Xiaochen Liu, Zeng South China Univ Technol Sch Civil Engn & Transportat Guangzhou 510630 Peoples R China Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China Imperial Coll London Dept Earth Sci & Engn London SW7 2BX England Huazhong Univ Sci & Technol Sch Naval Architecture & Ocean Engn Wuhan 430074 Peoples R China

A numerical study on the two-layer liquid sloshing with a free surface in a rectangular tank under horizontal sinusoidal excitation is investigated in this work. It is observed that the interface displacement is mainly influenced by the lower liquid depth, while the free surface displacement primarily depends on the total liquid depth. Using dimensional analysis of the numerical results, we obtained a fitting curve in the S-model expression, which relates the displacements of both liquids to the forcing amplitude, forcing frequency and liquid depth. Furthermore, distinct from the phenomena for a single-layer liquid, we find that the sum and difference frequencies play significant roles in the power spectral density curves. There are similar power spectral density curve shapes and energy concentration locations with a fixed type of excitation independent of the liquid filling depth and layer depths ratio.

关键词： Two-layer liquid sloshing Numerical analysis Dimensional analysis Power spectral density

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Stress intensity factor for a circumferential crack in a coke drum under two-dimensional transient temperature distribution

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INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING 2022年 200卷

作者： Wang, Zhiwen Ning, Zhihua Liu, Renhuai Jinan Univ Sch Mech & Construction Engn Key Lab Disaster Forecast & Control Engn Minist Educ China Guangzhou 510632 Peoples R China

Coke drums are subjected to extreme temperature cycling in service, leading to circumferential cracking in the drum wall. For a deeper understanding in the cracking mechanism, stress intensity factor (SIF) for a circumferential crack in a coke drum was investigated in this paper. Based on two-dimensional heat conduction theory and classical thin shell theory, analytical solutions for the transient temperature distribution, displacement, and thermal stress in the drum wall during hot feed filling and water quench steps were determined. The weight function method (WFM) was applied to investigate the mode I SIFs based on the analytical thermal stress solutions. Numerical simulations using finite element method (FEM) were also performed to validate the analytical solutions for both the thermos-elastic field and the SIFs. The effects of shell geometry, operating parameters and material properties on the SIF during the water quench step were discussed. It is shown that the SIF increases significantly as crack depth increases. A greater shell thickness or lower diameter to thickness ratio results in lower SIFs. Lower rising rate and higher temperature of quench water can reduce the SIF. The SIF increases as the thermal conductivity and thermal expansion coefficient of the drum wall materials increase. Finally, the SIFs for Cr-Mo steel and carbon steel coke drums are also discussed.

关键词： Coke drum Stress intensity factor Transient temperature distribution Circumferential crack Weight function

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An accurate and parameter-free analysis for the converse Poynting effect in large constrained torsion of highly elastic soft tubes

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ZAMM-ZEITSCHRIFT FUR ANGEWANDTE MATHEMATIK UND MECHANIK 2024年第2期104卷

作者： Tan, Long-Xu Kang, Jia Liu, Quan-Pu Wang, Si-Yu Bruhns, Otto Xiao, Heng 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 Ruhr Univ Bochum Inst Mech D-44780 Bochum Germany

New exact solutions to large constrained torsion of highly elastic soft tubes are obtained from a new hyper-elastic constitutive model. This new model is established with a new form of the multiaxial elastic potential toward simultaneously matching multiple data sets for three benchmark modes, including the uniaxial extension of a bar, the equi-biaxial extension of a thin plate and the plane-strain extension of a plate strip. With the new model, exact closed-form solutions to the stress responses for these benchmark modes are first derived and shown to be of decoupled nature, and, then, an accurate analysis for the converse Poynting effect of twisted highly elastic tubes with fixed ends is presented with a new technique in treating nonlinear coupling complexities. The main novelties are incorporated as follows. First, multiple data sets for three benchmark modes can be accurately and automatically matched with no need to identify any unknown parameters;next, the nonlinear coupled system of the governing equations for four variables in a twisted tube, including the averaged radius and the wall-thickness as well as the axial constrained stress and the shear stress, can be reduced to treating a single nonlinear equation;and, accordingly, the nonlinear coupling complexities can be worked out and exact results are obtainable.

关键词： Torsional stress

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Simplified analytical model for prediction of collapse resistance of restrained steel beam-column substructure exposed to fire

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engineering FAILURE ANALYSIS 2024年 159卷

作者： Guo, Zhan Cai, Wei Nie, Zhenhua Chen, Yu Jinan Univ Sch Mech & Construction Engn Guangzhou 510632 Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China Fuzhou Univ Coll Civil Engn Fuzhou 350116 Peoples R China

This paper provides a simplified analytical model for the restrained steel beam-column substructure under a fire-induced progressive collapse scenario, which is applied to predict the collapse resistance of substructures under fire. The simplified model is formulated for axially and rotationally restrained two-span steel beam-column substructures under column-loss scenarios and involves rigid and semi-rigid connections. The response characteristics of restrained substructures exposed to fire under column-loss scenarios in each response stage are elaborately analyzed. A "negative" catenary stage, in consideration of the unique negative axial force effects induced by the temperature thermal expansion, was first introduced in the five-stage simplified model for restrained substructures exposed to fire against progressive collapse. Subsequently, the explicit calculation formulas for determining the vertical loads and deflection of both rigid and semi-rigid joint substructures exposed to fire were derived in a quantified way, based on rigidplastic mechanisms and restraint coefficient methods. In addition, the corresponding numerical simulation analysis on a restrained two-span steel beam-column substructure with different end constraints and fire conditions was carried out to verify the applicability and reliability of established theoretical formulas. Comparisons of vertical load-deflection relationships between the calculation formulas and corresponding numerical simulation shows good accuracy. For more accurate prediction results, the error analysis was further conducted, and several theoretical formulas were modified, which were verified to be accurate and reliable after correction. With derived resistance functions, the resistance of steel beam-column substructures in fire-induced progressive collapse scenarios can be predicted.

关键词： Simplified analytical model Restrained beam-column substructure Collapse resistance Fire condition Numerical simulation Error analysis

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Multi-strategy structural damage detection based on included angle of vectors and sparse regularization

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STRUCTURAL engineering AND MECHANICS 2020年第4期75卷 415-424页

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

Recently, many structural damage detection (SDD) methods have been proposed to monitor the safety of structures. As an important modal parameter, mode shape has been widely used in SDD, and the difference of vectors was adopted based on sensitivity analysis and mode shapes in the existing studies. However, amplitudes of mode shapes in different measured points are relative values. Therefore, the difference of mode shapes will be influenced by their amplitudes, and the SDD results may be inaccurate. Focus on this deficiency, a multi-strategy SDD method is proposed based on the included angle of vectors and sparse regularization in this study. Firstly, inspired by modal assurance criterion (MAC), a relationship between mode shapes and changes in damage coefficients is established based on the included angle of vectors. Then, frequencies are introduced for multi-strategy SDD by a weighted coefficient. Meanwhile, sparse regularization is applied to improve the ill-posedness of the SDD problem. As a result, a novel convex optimization problem is proposed for effective SDD. To evaluate the effectiveness of the proposed method, numerical simulations in a planar truss and experimental studies in a six-story aluminum alloy frame in laboratory are conducted. The identified results indicate that the proposed method can effectively reduce the influence of noises, and it has good ability in locating structural damages and quantifying damage degrees.

关键词： structural damage detection (SDD) multi-strategy method sparse regularization included angle of vectors

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Anti-sparse representation for structural model updating using l∞ norm regularization

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STRUCTURAL engineering AND MECHANICS 2020年第4期75卷 477-485页

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

Finite element (FE) model based structural damage detection (SDD) methods play vital roles in effectively locating and quantifying structural damages. Among these methods, structural model updating should be conducted before SDD to obtain benchmark models of real structures. However, the characteristics of updating parameters are not reasonably considered in existing studies. Inspired by the l(infinity) norm regularization, a novel anti-sparse representation method is proposed for structural model updating in this study. Based on sensitivity analysis, both frequencies and mode shapes are used to define an objective function at first. Then, by adding l(infinity) norm penalty, an optimization problem is established for structural model updating As a result, the optimization problem can be solved by the fast iterative shrinkage thresholding algorithm (FISTA). Moreover, comparative studies with classical regularization strategy, i.e. the l(2) norm regularization method, are conducted as well. To intuitively illustrate the effectiveness of the proposed method, a 2-DOF spring-mass model is taken as an example in numerical simulations. The updating results show that the proposed method has a good robustness to measurement noises. Finally, to further verify the applicability of the proposed method, a six-storey aluminum alloy frame is designed and fabricated in laboratory. The added mass on each storey is taken as updating parameter. The updating results provide a good agreement with the true values, which indicates that the proposed method can effectively update the model parameters with a high accuracy.

关键词： structural model updating l(infinity) norm regularization anti-sparse representation sensitivity analysis

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A hybrid ant lion optimizer with improved Nelder-Mead algorithm for structural damage detection by improving weighted trace lasso regularization

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ADVANCES IN STRUCTURAL engineering 2020年第3期23卷 468-484页

作者： Chen, Chengbin Yu, Ling Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Sch Mech & Construct Engn Guangzhou Guangdong Peoples R China

Structural damage detection is the kernel technique in deploying structural health monitoring. The structural damage-detection technique using heuristic algorithms has been developed at an astounding pace over the past years. However, some existing structural damage-detection methods are prone to easily fall into the local optimum and to be unstable when they are applied to complex structures. In order to make full use of advantages of heuristic algorithms and overcome abovementioned shortcomings, a hybrid algorithm, which combines the ant lion optimizer with an improved Nelder-Mead algorithm, is proposed to solve the constrained optimization problem of complex structural damage detection. First, an objective function is established for damage identification using structural modal parameters, that is, frequencies and mode shapes. The solution to the objective function is accurately attained by a newly improved weighted trace lasso which can improve the computing performance and stability of procedure and reduce randomness of weighted coefficients. After assessing the computing performance of the proposed hybrid algorithm using three classical mathematical benchmark functions, two structural damage-detection numerical simulations and a laboratory verification are then conducted to fully assess the structural damage-detection capability of the proposed method. Meanwhile, the equivalent element stiffness-reduction model is introduced to estimate the real damage severities of cracks which are created in laboratory structures and to compare with the structural damage-detection results by the proposed method. The illustrated results show that the proposed hybrid algorithm can locate damage and quantify damage severity more accurately and stably with a good robustness to noise.

关键词： ant lion optimizer with an improved Nelder-Mead algorithm equivalent element stiffness-reduction model improved weighted trace lasso sparse regularization structural damage detection

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Experimental and numerical study on extended endplate beam-column joints after high temperature to resist progressive collapse

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JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH 2024年 219卷

作者： Guo, Zhan Yang, Kai Xing, Zhiquan Nie, Zhenhua Chen, 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 Fuzhou Univ Coll Civil Engn Fuzhou 350118 Peoples R China

This paper presents experimental and numerical investigations on the collapse -resisting behavior of extended endplate beam -column joints after high temperatures. The failure patterns and structural responses of extended endplate (EP) joints after high temperature to resist progressive collapse were first described, and then the effects of fire temperature and temperature duration on their collapse resistance mechanisms were also analyzed in detail. The test results demonstrate that all specimens withdrew from work owing to the serious deformation of endplate bolt holes or the brittle fracture of high -strength bolts, resulting in the catenary mechanisms of EP joints not being adequately developed. Compared with previous studies, it is shown that the fire temperature exerts the most significant effects on the carrying capacities and deformability of EP joints, and the collapse resistance of corresponding assemblies is most sensitive to the fire temperature. However, the temperature durations have an insignificant influence on the development of flexural mechanism resistance, especially for those after 600 degrees C and 800 degrees C. Moreover, the corresponding refined FE models in consideration of the damage and fracture of ductile metals have been established to reproduce the structural response of specimens after high temperature. To improve the post -fire collapse -resisting performance of assemblies, both the lateral plate reinforcement and welding reinforcement methods were proposed and compared with the assistance of validated FE models. From a practical viewpoint, the reinforcement with lateral plates is determined as a superior technique for post -fire EP joints against progressive collapse.

关键词： Extended endplate (EP) joints High temperature Progressive collapse Push -down tests Numerical simulation

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