This study presents a fragility curve to assess explosively induced damage to military vehicle tires based on shock tube experiments.To replicate lateral damage scenarios that may occur in real battlefield environment...This study presents a fragility curve to assess explosively induced damage to military vehicle tires based on shock tube experiments.To replicate lateral damage scenarios that may occur in real battlefield environments involving missile or bomb detonations,extreme overpressure conditions were generated using a shock tube.The influence of explosive charge mass on tire damage was quantitatively evaluated.Experimental results identified two critical failure thresholds:for loss of pressure,the threshold was 354 kPa peak overpressure and 3052 kPa·ms impulse;for rupture,the values were 485 kPa and 4237 kPa-ms,respectively.The same damage profile was reproduced through finite element analysis(FEA),verifying the reliability of the simulation.A Single Degree of Freedom(SDOF)model and Kingery-Bulmash(K-B)chart were employed to generate pressure-impulse data as a function of standoff distance.These data were applied to a finite element tire model using the BLAST ENHANCED keyword in LS-DYNA.The applied peak overpressures were identical to the experimental values with a 24%-27%difference in impulse.The simulation also captured recurring bead rim separation phenomenon,leading to internal pressure loss consistent with high-speed camera observations from the experiments.The resulting fragility curve clearly defines the threshold conditions for tire damage and provides a standardized damage assessment model applicable to various explosive charge masses and stand-off distances.The proposed model offers a quantitative basis for evaluating tire vulnerability,providing foundational reference data for defense applications.Specifically,the findings are expected to serve as a reliable source for weapon effects analysis and target vulnerability assessments involving wheeled military vehicles.展开更多
Aiming at addressing the issues of unclear dynamic response mechanisms and insufficient quantification of temperature coupling effects in building structures under long-duration blast loads,this study investigates typ...Aiming at addressing the issues of unclear dynamic response mechanisms and insufficient quantification of temperature coupling effects in building structures under long-duration blast loads,this study investigates typical composite beam-slab structures through integrated blast shock tube experiments and multiscale numerical simulations using Voronoi-coupled Finite-Discrete Element Method(VoroFDEM).The research systematically reveals the dynamic response mechanisms and damage evolution patterns of composite beam-slab structures subjected to prolonged blast loading.An environmenttemperature-coupled P-I curve damage assessment system is established,and a rapid evaluation method based on image crack characteristics is proposed,achieving innovative transition from traditional mechanical indicators to intelligent recognition paradigms.Results demonstrate that composite beam-slab structures exhibit three-phase failure modes:elastic vibration,plastic hinge formation,and global collapse.Numerical simulations identify the brittle-to-ductile transition temperature threshold at-10℃,and establish a temperature-dependent piecewise function-based P-I curve prediction model,whose overpressure asymptote displays nonlinear temperature sensitivity within-50-30℃.A novel dual-mode evaluation methodology integrating Voro-FDEM numerical simulations with image-based damage feature recognition is developed,enabling quantitative mapping between crack area and destruction levels.These findings provide theoretical foundations and technical pathways for rapid blast damage assessment and protective engineering design.展开更多
A model for evaluating structural damage of recycled aggregate concrete filled steel tube （RCFST） columns under seismic effects is proposed in this paper. The proposed model takes the lateral deformation and the eff...A model for evaluating structural damage of recycled aggregate concrete filled steel tube （RCFST） columns under seismic effects is proposed in this paper. The proposed model takes the lateral deformation and the effect of repeated cyclic loading into account. Available test results were collected and utilized to calibrate the parameters of the proposed model. A seismic test for six RCFST columns was also performed to validate the proposed damage assessment model. The main test parameters were the recycled coarse aggregate （RCA） replacement percentage and the bond-slip property. The test results indicated that the seismic performance of the RCFST member depends on the RCA contents and their damage index increases as the RCA replacement percentage increases. It is also indicated that the damage degree of RCFST changes with the variation of the RCA replacement percentage. Finally, comparisons between the RCA contents, lateral deformation ratio and damage degree were implemented. It is suggested that an improvement procedure should be implemented in order to compensate for the performance difference between the RCFST and normal concrete filled steel tubes （CFST）.展开更多
A damage assessment methodology based on the Hashin failure theory for glass fiber reinforced polymer(GFRP)composite blade is proposed. The typical failure mechanisms including the fiber tension/compression and matrix...A damage assessment methodology based on the Hashin failure theory for glass fiber reinforced polymer(GFRP)composite blade is proposed. The typical failure mechanisms including the fiber tension/compression and matrix tension/compression are considered to describe the damage behaviors. To give the flapwise and edgewise loading along the blade span, the Blade Element Momentum Theory(BEMT) is adopted. In conjunction with the hydrodynamic analysis, the structural analysis of the composite blade is cooperatively performed with the Hashin damage model. The damage characteristics of the composite blade, under normal and extreme operational conditions,are comparatively analyzed. Numerical results demonstrate that the matrix tension damage is the most significant failure mode which occurs in the mid-span of the blade. The blade internal configurations including the box-beam, Ibeam, left-C beam and right-C beam are compared and analyzed. The GFRP and carbon fiber reinforced polymer(CFRP) are considered and combined. Numerical results show that the I-beam is the best structural type. The structural performance of composite tidal turbine blades could be improved by combining the GFRP and CFRP structure considering the damage and cost-effectiveness synthetically.展开更多
Damage assessment of the wing under blast wave is essential to the vulnerability reduction design of aircraft. This paper introduces a critical relative distance prediction method of aircraft wing damage based on the ...Damage assessment of the wing under blast wave is essential to the vulnerability reduction design of aircraft. This paper introduces a critical relative distance prediction method of aircraft wing damage based on the back-propagation artificial neural network(BP-ANN), which is trained by finite element simulation results. Moreover, the finite element method(FEM) for wing blast damage simulation has been validated by ground explosion tests and further used for damage mode determination and damage characteristics analysis. The analysis results indicate that the wing is more likely to be damaged when the root is struck from vertical directions than others for a small charge. With the increase of TNT equivalent charge, the main damage mode of the wing gradually changes from the local skin tearing to overall structural deformation and the overpressure threshold of wing damage decreases rapidly. Compared to the FEM-based damage assessment, the BP-ANN-based method can predict the wing damage under a random blast wave with an average relative error of 4.78%. The proposed method and conclusions can be used as a reference for damage assessment under blast wave and low-vulnerability design of aircraft structures.展开更多
The synthetic aperture radar （SAR） plays an important role in earthquake emergency response because of its all-time and all-weather imaging capabilities. On April 14, 2010, an Ms7.1 earthquake occurred in Yushu coun...The synthetic aperture radar （SAR） plays an important role in earthquake emergency response because of its all-time and all-weather imaging capabilities. On April 14, 2010, an Ms7.1 earthquake occurred in Yushu county, Qinghai province of China, causing a lot of buildings collapsed. In this paper, the building damage in Yushu city due to the earthquake was assessed quantitatively using high-resolution X-band airborne SAR image. The features of the buildings with different damage levels （collapsed, partial collapsed, non-collapsed） in the SAR image were analyzed first. Based on these building features, we interpreted the individual building damage in Yushu city block by block and got the numbers of the collapsed, partial collapsed and non-collapsed buildings separately for each block, referring to pre-earthquake QuickBird image when necessary. Let the damage index of individual collapsed, partial collapsed, non-collapsed building be 1, 0.5, 0 respectively, the remote sensing damage index of each block was then calculated through remote sensing damage index equation. Finally, the preliminary quantitative relationship between the remote sensing damage index interpreted from the SAR image and that interpreted from the optical image was built up. It can be concluded that a desirable damage assessment result can be derived from high-resolution airborne SAR imagery.展开更多
A real case of a steel lattice shell suffering a fire was studied. Based on the theory of field modeling, fire dynamic simulator (FDS) was used to identify the temperature field. The damage mechanism of the structure ...A real case of a steel lattice shell suffering a fire was studied. Based on the theory of field modeling, fire dynamic simulator (FDS) was used to identify the temperature field. The damage mechanism of the structure was determined by FEM analysis. After damage assessment, the shell was repaired with the pipe-encasement method. Finally, field test was employed to check the capacity of the structure after repair. The numerical study results indicate that the damage assessment agrees well with field inspection, verifying the accuracy of fire numerical simulation and FEM analysis. The field test results prove that the pipe-encasement method is secure and reasonable, and the repaired shell is safe.展开更多
One common scenario during disasters such as earthquakes is that the activity of damage field reconnaissance on site is not well-coordinated. For example in Italy the damage assessment of structures after an earthquak...One common scenario during disasters such as earthquakes is that the activity of damage field reconnaissance on site is not well-coordinated. For example in Italy the damage assessment of structures after an earthquake is managed from the Italian Emergency Authority, using printed forms （AeDES） which are filled by experts on site generating a lot of confusion in filling and transferring the forms to the Disaster Management Operative Center. Because of this, the paper explores the viability of using mobile communication technologies （smart phones） and the Web to develop response systems that would aid communities after a major disaster, providing channels for allowing residents and responders ofuploading and distributing information, related to structural damages coordinating the damage field reconnaissance. A mobile application that can be run by residents on smart phones has been developed, to give an initial damage evaluation of the area, which is going to be very useful when resources （e.g. the number of experts is limited）. The mobile application has been tested for the first time during 2012 Emilia earthquake to enhance the emergency response, showing the efficiency of the proposed method in statistical terms comparing the proposed procedure with the standard procedure.展开更多
Battlefield damage assessment is the key to Battlefield Damage Assessment and Repair （ BDAR ） . We present an Intelligent Battlefield Damage Assessment System （IBDAS） based on multiagent system technology. We firs...Battlefield damage assessment is the key to Battlefield Damage Assessment and Repair （ BDAR ） . We present an Intelligent Battlefield Damage Assessment System （IBDAS） based on multiagent system technology. We first establish the system framework, and then study the interior structure and workflow of a problem allocation agent. The result shows that, there are many advantages to resolve the problem of battlefield damage assessment by applying multi-agent system technology, and it will bring significant military benefit.展开更多
Natural hazards such as hurricanes may cause extensive economic losses and social disruption for civil structures and infrastructures in coastal areas, implying the importance of understanding the construction perform...Natural hazards such as hurricanes may cause extensive economic losses and social disruption for civil structures and infrastructures in coastal areas, implying the importance of understanding the construction performance subjected to hurricanes and assessing the hurricane damages properly. The intensity and frequency of hurricanes have been reported to change with time due to the potential impact of climate change.In this paper, a probability-based model of hurricane damage assessment for coastal constructions is proposed taking into account the non-stationarity in hurricane intensity and frequency. The nonhomogeneous Poisson process is employed to model the non-stationarity in hurricane occurrence while the non-stationarity in hurricane intensity is reflected by the time-variant statistical parameters(e.g., mean value and/or standard deviation), with which the mean value and variation of the cumulative hurricane damage are evaluated explicitly. The Miami-Dade County, Florida, USA, is chosen to illustrate the hurricane damage assessment method proposed in this paper. The role of non-stationarity in hurricane intensity and occurrence rate due to climate change in hurricane damage is investigated using some representative changing patterns of hurricane parameters.展开更多
Due to the high population density and economic property in urban environments,urban flooding can result in substantial economic losses.However,accurate urban flood modeling and assessing the associated damages are ch...Due to the high population density and economic property in urban environments,urban flooding can result in substantial economic losses.However,accurate urban flood modeling and assessing the associated damages are challenging due to complex urban layouts and rugged topography.Furthermore,the rapid development of urban underground spaces has introduced additional complexities.To address the demanding need for accurate flood modeling and damage assessment in cities,a fine-scale flood damage assessment method was proposed in this study,based on the 1D/2D coupled hydrodynamic model,which can not only assess the flood damage on the ground surface but also evaluate the flood loss in underground spaces.Taking the Gangxi drainage area in Wuhan City,China as a case,this study extensively discussed the flood inundation processes on the ground surface as well as in the buildings and underground spaces,under different rainfall scenarios with the return period ranging from 2 to 200 years.Based on the high spatial-temporal hydrodynamic simulations,the flood damage degrees were evaluated for the buildings and underground spaces with different industry types.The results indicated that the inundation of buildings and underground spaces in densely built cities cannot be neglected in urban flood modeling.Buildings with public service attributes can have a higher flood damage degree,as compared with other types of buildings and underground spaces.展开更多
The soil-structure interaction (SSI) decoupling is applied to simplify buried structure against internal blast load as spring effect. Shear failure, bending failure and combined failure modes are considered based on f...The soil-structure interaction (SSI) decoupling is applied to simplify buried structure against internal blast load as spring effect. Shear failure, bending failure and combined failure modes are considered based on five transverse velocity profiles for the rigid-plastic structural element. The critical equations for shear and bending failure are derived respectively. Pressureimpulse diagrams are accordingly developed to assess damage of the buried structures against internal blast load. Comparison is done to show influences of soil-structure interaction and shear-to-bending strength ratio of a structural element. A case study is conducted to show the application of damage assessment to a reinforced concrete beam element of buried structure.展开更多
A practical method for visualizing flood area and evaluating damage is presented,which consists of two technical approaches:self-programming and adapting commercial GIS platforms.The low-cost and easy-to-use GIS-Based...A practical method for visualizing flood area and evaluating damage is presented,which consists of two technical approaches:self-programming and adapting commercial GIS platforms.The low-cost and easy-to-use GIS-Based model developed by self-programming can meet current requirements of most local authorities,especially in developing countries.In this model,two cases,non-source flood and source flood,are distinguished and the Seed-spread algorithm suitable for source-flood is discussed;The flood damage is assessed by overlaying the flood area range with thematic maps and other related social and economic data.and all thematic maps are converted to raster format before overlay analysis.Two measures are taken to improve the operation efficiency of speed seed-spread algorithm.The accuracy of the model mainly depends on the resolution and precision of the DEM data,and the accuracy of registering all raster layers and the quality of attribute data.展开更多
The new cross spectral energy method(CSEM)is proposed for maintaining cable-stayed bridge safe-ty by the measurable output-only vibration response.Damage assessment of real structures is limited by aseries of problems...The new cross spectral energy method(CSEM)is proposed for maintaining cable-stayed bridge safe-ty by the measurable output-only vibration response.Damage assessment of real structures is limited by aseries of problems such as unknown ambient excitation forces,errors introduced by system identification,incomplete dynamic measurements,etc.Thus the methodology based on cross spectral energy of eachsubstructure member is derived to meet these challenges.The novel damage index does not require anymodal or parameter identification technology.It can be calculated directly from vibration test data.In or-der to evaluate the efficiency of the presented methodology,a three dimensional(3D)actual cable-stayedbridge model with one or more damaged positions under operational conditions was studied.In order totestify the reliability of damage detection method,the response data was polluted by the random noise.Itis proved that the proposed method can successfully localize all damage cases even in noisy data.Withthe help of examples,the CSEM can potentially be applied as a nondestructive evaluation technique(NDT)for on-line health monitoring of cable-stayed bridges with minimum disruption of its operations.展开更多
C_(f)/SiC composites are characterized as anisotropic,heterogeneous,brittle,and hard materials.The process of manufacturing C_(f)/SiC composites using traditional machining techniques is prone to edge chipping damage ...C_(f)/SiC composites are characterized as anisotropic,heterogeneous,brittle,and hard materials.The process of manufacturing C_(f)/SiC composites using traditional machining techniques is prone to edge chipping damage and tool wear,which makes it difficult to meet the machining quality and machining accuracy.The purpose of this paper is to investigate the milling characteristics and damage assessment during ultrasonic vibration-assisted end milling(UVAEM)of C_(f)/SiC composites.Firstly,UVAEM experiments on C_(f)/SiC composites were carried out at different ultrasonic amplitudes and comparative experiments with conventional milling(CM).In addition,tool wear,surface roughness,surface micromorphology,milling force and subsurface damage(SSD)were measured and analysed.Finally,the SSD factors of C_(f)/SiC composites were established to quantify machining damage,and analyzed the effect of ultrasonic amplitude on SSD.Furthermore,the formation mechanism of SSD was investigated and discussed.The findings indicate that appropriate ultrasonic amplitude improves the surface quality by UVAEM,while excessive amplitude deteriorates the surface quality.During the UVAEM,micro/macro brittle fracture of the fibers on the surface occurs,leading to machining defects such as fiber breakage,fiber-interface debonding and pits.The milling force gradually decreases with the increase of ultrasonic amplitude.On the other hand,the forms of SSD in CM and UVAEM are mainly fiber pullout,subsurface crack,crack extension and machining pits.Matrix cracking and fiber pullout in SSD were affected by fiber orientation.Moreover,the introduction of ultrasonic vibration plays a significant contribution in the inhibition of the SSD in C_(f)/SiC composites.展开更多
The fast processing, seismic damage data extraction and loss evaluation from RS imagery acquired immediately after a destructive earthquake occurs, are important means for compen- sating the insufficiency of seismic d...The fast processing, seismic damage data extraction and loss evaluation from RS imagery acquired immediately after a destructive earthquake occurs, are important means for compen- sating the insufficiency of seismic damage information from ground-based investigations and provide an important basis for emergency command and rescue. The paper introduces the method of emergency seismic damage assessment using remote sensing data and its application to the great Wenchuan earthquake of magnitude 8.0 occurring in southwest Sichuan Province on May 12, 2008. The practical effectiveness of the method is also evaluated in the paper.展开更多
This paper introduces a new methodology for the damage assessment of existing-transmission structures using six layers, zero order Sugeno model. The model is a hybrid fuzzy-neural system that combines the power of neu...This paper introduces a new methodology for the damage assessment of existing-transmission structures using six layers, zero order Sugeno model. The model is a hybrid fuzzy-neural system that combines the power of neural networks and fuzzy systems. It is a learning expert system that finds the parameters of the fuzzy sets and fuzzy rules by exploiting approximation techniques from neural networks. The condition ratings of the structural components are determined based on visually observed deterioration-symptoms and the severity of those symptoms. A supervised learning process using training data and expert opinions is used to develop the expert system rules and determine the ratings of the structural components. For the learning from training data, the model uses a combination of least-square estimator and gradient descent method. A sequential least square algorithm is used to determine the weighting factors that minimized the errors. A test case is given to illustrate the power of the proposed fuzzy-neural system. It is concluded that the Sugeno model＇s ability to tune the parameters based on the training data makes it superior to the rules produced by an expert in the conventional fuzzy logic systems.展开更多
Electrochemical impedance spectroscopy(EIS)was used to examine the electrical properties of metakaolin(MK)cement-based materials at elevated temperatures.We utilized a new equivalent circuit to investigate the EIS res...Electrochemical impedance spectroscopy(EIS)was used to examine the electrical properties of metakaolin(MK)cement-based materials at elevated temperatures.We utilized a new equivalent circuit to investigate the EIS results of cementitious materials blended with MK at these temperatures.A new evaluation method to high temperature damage is proposed.The findings show that both elevated temperatures and MK contents in cement mortar can impact the impedance spectra’s form properties.However,the residual compressive strength of the MK-blended cementitious material at elevated temperatures does not improve with the addition of MK.A quantitative relationship between the electrochemical parameters of the new equivalent circuit and the residual compressive strength is determined.The degree of high-temperature damage to cementitious materials can be evaluated based on these electrochemical parameters,providing a new approach for evaluating the high-temperature damage of MK-blend cementitious materials.展开更多
Objective: To analyze the effectiveness of musculoskeletal ultrasound in diagnosing rotator cuff injuries. Methods: A total of 80 patients with suspected rotator cuff injuries who were admitted and diagnosed between J...Objective: To analyze the effectiveness of musculoskeletal ultrasound in diagnosing rotator cuff injuries. Methods: A total of 80 patients with suspected rotator cuff injuries who were admitted and diagnosed between January 1, 2020, and December 31, 2024, were selected. Musculoskeletal ultrasound was performed on these patients, and the diagnostic efficacy of musculoskeletal ultrasound was evaluated by comparing the results with those of MRI. Results: The detection rates of musculoskeletal ultrasound for the location and extent of injury were similar to those of MRI (p > 0.05). Based on the MRI diagnosis results, the diagnostic accuracy rate of musculoskeletal ultrasound was 92.50%, with a sensitivity of 93.06% and a specificity of 87.50%. The morphological and signal characteristics, as well as ultrasound indicators, of patients with positive musculoskeletal ultrasound results differed significantly from those of patients with negative results (p < 0.05). Conclusion: Musculoskeletal ultrasound can effectively detect the location and extent of rotator cuff injuries, comprehensively assess the damage, and demonstrate high diagnostic efficacy. Furthermore, the morphological and signal characteristics, as well as ultrasound indicators, of musculoskeletal ultrasound can serve as diagnostic criteria for rotator cuff injuries, improving disease detection efficiency.展开更多
Flood damage assessment(FDA)is a key component of risk-based method for flood management.In the current FDA approaches,generally the uniqueness of the building is disregarded in the analysis.Therefore,they are unfit f...Flood damage assessment(FDA)is a key component of risk-based method for flood management.In the current FDA approaches,generally the uniqueness of the building is disregarded in the analysis.Therefore,they are unfit for detailed applications in which case-by-case analysis of building damage is an essential requirement.This limitation is compounded by the use of incomplete and often low-quality data inputs about the building and the assumptions and approximations made regarding the geometry and materials of its components.Such shortcomings may result in incomplete and uncertain outcomes.Considering the benefits and increasing use of three-dimensional(3D)urban modeling and Building Information Model in various urban management processes,in this paper,an integrated framework for utilization of detailed 3D building models for the assessment and 3D visualization of flood damage to building according to its distinct behavior against flood is presented.A proof-ofconcept demonstration of the framework in a case study underlined the feasibility of implementation of the framework,which can potentially benefit a variety of users and be used as a complementary approach to the current FDA methods for improving the resilience of the community toward floods and their adverse impacts.展开更多
基金part of the Agency for Defense Development(ADD)research project on Weapon lethality/effectiveness analysis technology for material targets and grant funded by the korean goverment(511225-912A03301)。
文摘This study presents a fragility curve to assess explosively induced damage to military vehicle tires based on shock tube experiments.To replicate lateral damage scenarios that may occur in real battlefield environments involving missile or bomb detonations,extreme overpressure conditions were generated using a shock tube.The influence of explosive charge mass on tire damage was quantitatively evaluated.Experimental results identified two critical failure thresholds:for loss of pressure,the threshold was 354 kPa peak overpressure and 3052 kPa·ms impulse;for rupture,the values were 485 kPa and 4237 kPa-ms,respectively.The same damage profile was reproduced through finite element analysis(FEA),verifying the reliability of the simulation.A Single Degree of Freedom(SDOF)model and Kingery-Bulmash(K-B)chart were employed to generate pressure-impulse data as a function of standoff distance.These data were applied to a finite element tire model using the BLAST ENHANCED keyword in LS-DYNA.The applied peak overpressures were identical to the experimental values with a 24%-27%difference in impulse.The simulation also captured recurring bead rim separation phenomenon,leading to internal pressure loss consistent with high-speed camera observations from the experiments.The resulting fragility curve clearly defines the threshold conditions for tire damage and provides a standardized damage assessment model applicable to various explosive charge masses and stand-off distances.The proposed model offers a quantitative basis for evaluating tire vulnerability,providing foundational reference data for defense applications.Specifically,the findings are expected to serve as a reliable source for weapon effects analysis and target vulnerability assessments involving wheeled military vehicles.
基金supported by Open Research Fund of State Key Laboratory of Target Vulnerability Assessment,Defense Engineering Institute,AMS,PLA(Grant No.YSX2024KFPG002)。
文摘Aiming at addressing the issues of unclear dynamic response mechanisms and insufficient quantification of temperature coupling effects in building structures under long-duration blast loads,this study investigates typical composite beam-slab structures through integrated blast shock tube experiments and multiscale numerical simulations using Voronoi-coupled Finite-Discrete Element Method(VoroFDEM).The research systematically reveals the dynamic response mechanisms and damage evolution patterns of composite beam-slab structures subjected to prolonged blast loading.An environmenttemperature-coupled P-I curve damage assessment system is established,and a rapid evaluation method based on image crack characteristics is proposed,achieving innovative transition from traditional mechanical indicators to intelligent recognition paradigms.Results demonstrate that composite beam-slab structures exhibit three-phase failure modes:elastic vibration,plastic hinge formation,and global collapse.Numerical simulations identify the brittle-to-ductile transition temperature threshold at-10℃,and establish a temperature-dependent piecewise function-based P-I curve prediction model,whose overpressure asymptote displays nonlinear temperature sensitivity within-50-30℃.A novel dual-mode evaluation methodology integrating Voro-FDEM numerical simulations with image-based damage feature recognition is developed,enabling quantitative mapping between crack area and destruction levels.These findings provide theoretical foundations and technical pathways for rapid blast damage assessment and protective engineering design.
基金the National Natural Science Foundation of China under Grant Nos.51408346 and 51438007the Shanghai Science and Technique Committee under Grant No.14231201300
文摘A model for evaluating structural damage of recycled aggregate concrete filled steel tube （RCFST） columns under seismic effects is proposed in this paper. The proposed model takes the lateral deformation and the effect of repeated cyclic loading into account. Available test results were collected and utilized to calibrate the parameters of the proposed model. A seismic test for six RCFST columns was also performed to validate the proposed damage assessment model. The main test parameters were the recycled coarse aggregate （RCA） replacement percentage and the bond-slip property. The test results indicated that the seismic performance of the RCFST member depends on the RCA contents and their damage index increases as the RCA replacement percentage increases. It is also indicated that the damage degree of RCFST changes with the variation of the RCA replacement percentage. Finally, comparisons between the RCA contents, lateral deformation ratio and damage degree were implemented. It is suggested that an improvement procedure should be implemented in order to compensate for the performance difference between the RCFST and normal concrete filled steel tubes （CFST）.
基金financially supported by the Marine Renewable Energy Research Project of State Oceanic Administration of China(Grant No.GHME2013GC03)
文摘A damage assessment methodology based on the Hashin failure theory for glass fiber reinforced polymer(GFRP)composite blade is proposed. The typical failure mechanisms including the fiber tension/compression and matrix tension/compression are considered to describe the damage behaviors. To give the flapwise and edgewise loading along the blade span, the Blade Element Momentum Theory(BEMT) is adopted. In conjunction with the hydrodynamic analysis, the structural analysis of the composite blade is cooperatively performed with the Hashin damage model. The damage characteristics of the composite blade, under normal and extreme operational conditions,are comparatively analyzed. Numerical results demonstrate that the matrix tension damage is the most significant failure mode which occurs in the mid-span of the blade. The blade internal configurations including the box-beam, Ibeam, left-C beam and right-C beam are compared and analyzed. The GFRP and carbon fiber reinforced polymer(CFRP) are considered and combined. Numerical results show that the I-beam is the best structural type. The structural performance of composite tidal turbine blades could be improved by combining the GFRP and CFRP structure considering the damage and cost-effectiveness synthetically.
基金supported by the Natural Science Foundation of Shaanxi Province (Grant No. 2020JQ-122)the Fund support of Science and Technology on Transient Impact Laboratory。
文摘Damage assessment of the wing under blast wave is essential to the vulnerability reduction design of aircraft. This paper introduces a critical relative distance prediction method of aircraft wing damage based on the back-propagation artificial neural network(BP-ANN), which is trained by finite element simulation results. Moreover, the finite element method(FEM) for wing blast damage simulation has been validated by ground explosion tests and further used for damage mode determination and damage characteristics analysis. The analysis results indicate that the wing is more likely to be damaged when the root is struck from vertical directions than others for a small charge. With the increase of TNT equivalent charge, the main damage mode of the wing gradually changes from the local skin tearing to overall structural deformation and the overpressure threshold of wing damage decreases rapidly. Compared to the FEM-based damage assessment, the BP-ANN-based method can predict the wing damage under a random blast wave with an average relative error of 4.78%. The proposed method and conclusions can be used as a reference for damage assessment under blast wave and low-vulnerability design of aircraft structures.
基金supported by the Project "Study on the key techniques of remote sensing applied to earthquake emergency management" funded by Ministry of Science & Technology of China(No.2009DFA21610)
文摘The synthetic aperture radar （SAR） plays an important role in earthquake emergency response because of its all-time and all-weather imaging capabilities. On April 14, 2010, an Ms7.1 earthquake occurred in Yushu county, Qinghai province of China, causing a lot of buildings collapsed. In this paper, the building damage in Yushu city due to the earthquake was assessed quantitatively using high-resolution X-band airborne SAR image. The features of the buildings with different damage levels （collapsed, partial collapsed, non-collapsed） in the SAR image were analyzed first. Based on these building features, we interpreted the individual building damage in Yushu city block by block and got the numbers of the collapsed, partial collapsed and non-collapsed buildings separately for each block, referring to pre-earthquake QuickBird image when necessary. Let the damage index of individual collapsed, partial collapsed, non-collapsed building be 1, 0.5, 0 respectively, the remote sensing damage index of each block was then calculated through remote sensing damage index equation. Finally, the preliminary quantitative relationship between the remote sensing damage index interpreted from the SAR image and that interpreted from the optical image was built up. It can be concluded that a desirable damage assessment result can be derived from high-resolution airborne SAR imagery.
基金Supported by National Natural Science Foundation of China (No. 50778122)
文摘A real case of a steel lattice shell suffering a fire was studied. Based on the theory of field modeling, fire dynamic simulator (FDS) was used to identify the temperature field. The damage mechanism of the structure was determined by FEM analysis. After damage assessment, the shell was repaired with the pipe-encasement method. Finally, field test was employed to check the capacity of the structure after repair. The numerical study results indicate that the damage assessment agrees well with field inspection, verifying the accuracy of fire numerical simulation and FEM analysis. The field test results prove that the pipe-encasement method is secure and reasonable, and the repaired shell is safe.
基金funding from the European Community's Seventh Framework Programme-Marie Curie International Reintegration Actions-FP7/2007-2013 under the Grant Agreement No. PIRG06-GA-2009-256316 of the project ICRED-Integrated European Disaster Community Resiliencesponsored by the Israel-Italy Joint Innovation Program for Industrial, Scientific and Technological Cooperation in R&D, EUREKA Label under the Grant agreement No. 3435777CDC of the project ECRIS-European Communities resilient integrated through Smart Phones
文摘One common scenario during disasters such as earthquakes is that the activity of damage field reconnaissance on site is not well-coordinated. For example in Italy the damage assessment of structures after an earthquake is managed from the Italian Emergency Authority, using printed forms （AeDES） which are filled by experts on site generating a lot of confusion in filling and transferring the forms to the Disaster Management Operative Center. Because of this, the paper explores the viability of using mobile communication technologies （smart phones） and the Web to develop response systems that would aid communities after a major disaster, providing channels for allowing residents and responders ofuploading and distributing information, related to structural damages coordinating the damage field reconnaissance. A mobile application that can be run by residents on smart phones has been developed, to give an initial damage evaluation of the area, which is going to be very useful when resources （e.g. the number of experts is limited）. The mobile application has been tested for the first time during 2012 Emilia earthquake to enhance the emergency response, showing the efficiency of the proposed method in statistical terms comparing the proposed procedure with the standard procedure.
文摘Battlefield damage assessment is the key to Battlefield Damage Assessment and Repair （ BDAR ） . We present an Intelligent Battlefield Damage Assessment System （IBDAS） based on multiagent system technology. We first establish the system framework, and then study the interior structure and workflow of a problem allocation agent. The result shows that, there are many advantages to resolve the problem of battlefield damage assessment by applying multi-agent system technology, and it will bring significant military benefit.
基金The National Natural Science Foundation of China under contract No.51578315the Major Projects Fund of Chinese Ministry of Transport under contract No.201332849A090
文摘Natural hazards such as hurricanes may cause extensive economic losses and social disruption for civil structures and infrastructures in coastal areas, implying the importance of understanding the construction performance subjected to hurricanes and assessing the hurricane damages properly. The intensity and frequency of hurricanes have been reported to change with time due to the potential impact of climate change.In this paper, a probability-based model of hurricane damage assessment for coastal constructions is proposed taking into account the non-stationarity in hurricane intensity and frequency. The nonhomogeneous Poisson process is employed to model the non-stationarity in hurricane occurrence while the non-stationarity in hurricane intensity is reflected by the time-variant statistical parameters(e.g., mean value and/or standard deviation), with which the mean value and variation of the cumulative hurricane damage are evaluated explicitly. The Miami-Dade County, Florida, USA, is chosen to illustrate the hurricane damage assessment method proposed in this paper. The role of non-stationarity in hurricane intensity and occurrence rate due to climate change in hurricane damage is investigated using some representative changing patterns of hurricane parameters.
基金National Natural Science Foundation of China,Grant/Award Numbers:41890820,51725902,52209098Special Fund for Science and Technology Innovation Strategy of Guangdong Province,Grant/Award Number:gdsky2023-02+1 种基金Newton Advanced Fellowships from the NSFC and the UK Royal Society,Grant/Award Numbers:52061130219,NAF\R1\201156Science and Technology Innovation Program from Water Resources of Guangdong Province,Grant/Award Numbers:2022-01,2023-05。
文摘Due to the high population density and economic property in urban environments,urban flooding can result in substantial economic losses.However,accurate urban flood modeling and assessing the associated damages are challenging due to complex urban layouts and rugged topography.Furthermore,the rapid development of urban underground spaces has introduced additional complexities.To address the demanding need for accurate flood modeling and damage assessment in cities,a fine-scale flood damage assessment method was proposed in this study,based on the 1D/2D coupled hydrodynamic model,which can not only assess the flood damage on the ground surface but also evaluate the flood loss in underground spaces.Taking the Gangxi drainage area in Wuhan City,China as a case,this study extensively discussed the flood inundation processes on the ground surface as well as in the buildings and underground spaces,under different rainfall scenarios with the return period ranging from 2 to 200 years.Based on the high spatial-temporal hydrodynamic simulations,the flood damage degrees were evaluated for the buildings and underground spaces with different industry types.The results indicated that the inundation of buildings and underground spaces in densely built cities cannot be neglected in urban flood modeling.Buildings with public service attributes can have a higher flood damage degree,as compared with other types of buildings and underground spaces.
文摘The soil-structure interaction (SSI) decoupling is applied to simplify buried structure against internal blast load as spring effect. Shear failure, bending failure and combined failure modes are considered based on five transverse velocity profiles for the rigid-plastic structural element. The critical equations for shear and bending failure are derived respectively. Pressureimpulse diagrams are accordingly developed to assess damage of the buried structures against internal blast load. Comparison is done to show influences of soil-structure interaction and shear-to-bending strength ratio of a structural element. A case study is conducted to show the application of damage assessment to a reinforced concrete beam element of buried structure.
文摘A practical method for visualizing flood area and evaluating damage is presented,which consists of two technical approaches:self-programming and adapting commercial GIS platforms.The low-cost and easy-to-use GIS-Based model developed by self-programming can meet current requirements of most local authorities,especially in developing countries.In this model,two cases,non-source flood and source flood,are distinguished and the Seed-spread algorithm suitable for source-flood is discussed;The flood damage is assessed by overlaying the flood area range with thematic maps and other related social and economic data.and all thematic maps are converted to raster format before overlay analysis.Two measures are taken to improve the operation efficiency of speed seed-spread algorithm.The accuracy of the model mainly depends on the resolution and precision of the DEM data,and the accuracy of registering all raster layers and the quality of attribute data.
基金the Research Fund for the Doctoral Program of Higher Education(No.20070248104)the National Key Natural Science Foundation of China(No.50739004)
文摘The new cross spectral energy method(CSEM)is proposed for maintaining cable-stayed bridge safe-ty by the measurable output-only vibration response.Damage assessment of real structures is limited by aseries of problems such as unknown ambient excitation forces,errors introduced by system identification,incomplete dynamic measurements,etc.Thus the methodology based on cross spectral energy of eachsubstructure member is derived to meet these challenges.The novel damage index does not require anymodal or parameter identification technology.It can be calculated directly from vibration test data.In or-der to evaluate the efficiency of the presented methodology,a three dimensional(3D)actual cable-stayedbridge model with one or more damaged positions under operational conditions was studied.In order totestify the reliability of damage detection method,the response data was polluted by the random noise.Itis proved that the proposed method can successfully localize all damage cases even in noisy data.Withthe help of examples,the CSEM can potentially be applied as a nondestructive evaluation technique(NDT)for on-line health monitoring of cable-stayed bridges with minimum disruption of its operations.
基金Supported by National Key Research and Development Program of China(Grant Nos.2019YFA0708902,2022YFB3404002)Fundamental Research Funds for the Central Universities of China(Grant No.DUT22LAB501)+1 种基金National Science Foundation for Distinguished Young Scholars of China(Grant No.52325506)National Natural Science Foundation of China(Grant No.52275411)。
文摘C_(f)/SiC composites are characterized as anisotropic,heterogeneous,brittle,and hard materials.The process of manufacturing C_(f)/SiC composites using traditional machining techniques is prone to edge chipping damage and tool wear,which makes it difficult to meet the machining quality and machining accuracy.The purpose of this paper is to investigate the milling characteristics and damage assessment during ultrasonic vibration-assisted end milling(UVAEM)of C_(f)/SiC composites.Firstly,UVAEM experiments on C_(f)/SiC composites were carried out at different ultrasonic amplitudes and comparative experiments with conventional milling(CM).In addition,tool wear,surface roughness,surface micromorphology,milling force and subsurface damage(SSD)were measured and analysed.Finally,the SSD factors of C_(f)/SiC composites were established to quantify machining damage,and analyzed the effect of ultrasonic amplitude on SSD.Furthermore,the formation mechanism of SSD was investigated and discussed.The findings indicate that appropriate ultrasonic amplitude improves the surface quality by UVAEM,while excessive amplitude deteriorates the surface quality.During the UVAEM,micro/macro brittle fracture of the fibers on the surface occurs,leading to machining defects such as fiber breakage,fiber-interface debonding and pits.The milling force gradually decreases with the increase of ultrasonic amplitude.On the other hand,the forms of SSD in CM and UVAEM are mainly fiber pullout,subsurface crack,crack extension and machining pits.Matrix cracking and fiber pullout in SSD were affected by fiber orientation.Moreover,the introduction of ultrasonic vibration plays a significant contribution in the inhibition of the SSD in C_(f)/SiC composites.
基金sponsored by the National Science and Technological Support Program of the 11th "Five-year Plan"(2006BAC01B02-01-01)
文摘The fast processing, seismic damage data extraction and loss evaluation from RS imagery acquired immediately after a destructive earthquake occurs, are important means for compen- sating the insufficiency of seismic damage information from ground-based investigations and provide an important basis for emergency command and rescue. The paper introduces the method of emergency seismic damage assessment using remote sensing data and its application to the great Wenchuan earthquake of magnitude 8.0 occurring in southwest Sichuan Province on May 12, 2008. The practical effectiveness of the method is also evaluated in the paper.
文摘This paper introduces a new methodology for the damage assessment of existing-transmission structures using six layers, zero order Sugeno model. The model is a hybrid fuzzy-neural system that combines the power of neural networks and fuzzy systems. It is a learning expert system that finds the parameters of the fuzzy sets and fuzzy rules by exploiting approximation techniques from neural networks. The condition ratings of the structural components are determined based on visually observed deterioration-symptoms and the severity of those symptoms. A supervised learning process using training data and expert opinions is used to develop the expert system rules and determine the ratings of the structural components. For the learning from training data, the model uses a combination of least-square estimator and gradient descent method. A sequential least square algorithm is used to determine the weighting factors that minimized the errors. A test case is given to illustrate the power of the proposed fuzzy-neural system. It is concluded that the Sugeno model＇s ability to tune the parameters based on the training data makes it superior to the rules produced by an expert in the conventional fuzzy logic systems.
基金Funded by the Natural Science Foundation of Inner Mongolia Autonomous Region(No.2024QN05023)High Level Talent Research Launch Foundation of Inner Mongolia University(No.10000-22311201/008)。
文摘Electrochemical impedance spectroscopy(EIS)was used to examine the electrical properties of metakaolin(MK)cement-based materials at elevated temperatures.We utilized a new equivalent circuit to investigate the EIS results of cementitious materials blended with MK at these temperatures.A new evaluation method to high temperature damage is proposed.The findings show that both elevated temperatures and MK contents in cement mortar can impact the impedance spectra’s form properties.However,the residual compressive strength of the MK-blended cementitious material at elevated temperatures does not improve with the addition of MK.A quantitative relationship between the electrochemical parameters of the new equivalent circuit and the residual compressive strength is determined.The degree of high-temperature damage to cementitious materials can be evaluated based on these electrochemical parameters,providing a new approach for evaluating the high-temperature damage of MK-blend cementitious materials.
文摘Objective: To analyze the effectiveness of musculoskeletal ultrasound in diagnosing rotator cuff injuries. Methods: A total of 80 patients with suspected rotator cuff injuries who were admitted and diagnosed between January 1, 2020, and December 31, 2024, were selected. Musculoskeletal ultrasound was performed on these patients, and the diagnostic efficacy of musculoskeletal ultrasound was evaluated by comparing the results with those of MRI. Results: The detection rates of musculoskeletal ultrasound for the location and extent of injury were similar to those of MRI (p > 0.05). Based on the MRI diagnosis results, the diagnostic accuracy rate of musculoskeletal ultrasound was 92.50%, with a sensitivity of 93.06% and a specificity of 87.50%. The morphological and signal characteristics, as well as ultrasound indicators, of patients with positive musculoskeletal ultrasound results differed significantly from those of patients with negative results (p < 0.05). Conclusion: Musculoskeletal ultrasound can effectively detect the location and extent of rotator cuff injuries, comprehensively assess the damage, and demonstrate high diagnostic efficacy. Furthermore, the morphological and signal characteristics, as well as ultrasound indicators, of musculoskeletal ultrasound can serve as diagnostic criteria for rotator cuff injuries, improving disease detection efficiency.
基金supported by the Australian Research Council[grant number LP0990135].
文摘Flood damage assessment(FDA)is a key component of risk-based method for flood management.In the current FDA approaches,generally the uniqueness of the building is disregarded in the analysis.Therefore,they are unfit for detailed applications in which case-by-case analysis of building damage is an essential requirement.This limitation is compounded by the use of incomplete and often low-quality data inputs about the building and the assumptions and approximations made regarding the geometry and materials of its components.Such shortcomings may result in incomplete and uncertain outcomes.Considering the benefits and increasing use of three-dimensional(3D)urban modeling and Building Information Model in various urban management processes,in this paper,an integrated framework for utilization of detailed 3D building models for the assessment and 3D visualization of flood damage to building according to its distinct behavior against flood is presented.A proof-ofconcept demonstration of the framework in a case study underlined the feasibility of implementation of the framework,which can potentially benefit a variety of users and be used as a complementary approach to the current FDA methods for improving the resilience of the community toward floods and their adverse impacts.
