G. H. Cavalcante, E. Pereira, I. D. Rodrigues, Luiz Carlos Marcos Vieira Júnior, J. Padgett, G. Siqueira
This paper presents a seismic fragility assessment of bridges commonly found in Northeastern Brazil. A generic three-dimensional nonlinear finite-element model is generated in OpenSees to enable variation of geometric features and component modeling. A parametric analysis is performed to evaluate the impact of the geometric and physical variations of the bridge inventory on the seismic behavior of the structures. Nonlinear time-history analyses using four sets of natural earthquake records are performed to obtain the Probabilistic Seismic Demand Model for the bridges. Capacity models are adopted according to previous studies to be combined with demand models to generate fragility functions. This article helps the decision markers to predict the seismic behavior of typical bridges in Northeastern Brazil, which enables the evaluation of risk mitigation methods.
{"title":"Seismic fragility assessment of typical bridges in Northeastern Brazil","authors":"G. H. Cavalcante, E. Pereira, I. D. Rodrigues, Luiz Carlos Marcos Vieira Júnior, J. Padgett, G. Siqueira","doi":"10.1590/1679-78257062","DOIUrl":"https://doi.org/10.1590/1679-78257062","url":null,"abstract":"This paper presents a seismic fragility assessment of bridges commonly found in Northeastern Brazil. A generic three-dimensional nonlinear finite-element model is generated in OpenSees to enable variation of geometric features and component modeling. A parametric analysis is performed to evaluate the impact of the geometric and physical variations of the bridge inventory on the seismic behavior of the structures. Nonlinear time-history analyses using four sets of natural earthquake records are performed to obtain the Probabilistic Seismic Demand Model for the bridges. Capacity models are adopted according to previous studies to be combined with demand models to generate fragility functions. This article helps the decision markers to predict the seismic behavior of typical bridges in Northeastern Brazil, which enables the evaluation of risk mitigation methods.","PeriodicalId":18192,"journal":{"name":"Latin American Journal of Solids and Structures","volume":"1 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67620209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
W. L. Fernandes, Gustavo Botelho Barbosa, M. Greco, R. Silveira
The present paper aims to test recent (Truly self-starting two sub-step method and three-parameter single-step implicit method) and classical (Generalized-α, HHT - α, and WBZ - α methods) time integration methods using the geometrically nonlinear Positional Finite Element Method (PFEM). The numerical formulation is based on the total Lagrangian approach and uses the Hessian matrix to obtain the response. The mixed hardening inelastic model applied to PFEM is also presented. Two examples validate the time integration algorithms and the inelastic model. In the first example, the mixed hardening inelastic model is compared with the the bilinear stress-strain model and the elastic-perfectly plastic hinge model, and aspects such as amplitude decay and period elongation are discussed. In the second example, the implemented algorithms are verified in a severe geometrically nonlinear example, considering the influence of numerical dissipation, time interval, and the number of elements in the response. Results show the relevance of numerical damping for numerical stabilization and the good performance of the Generalized-α algorithm.
{"title":"Comparison between recent implicit time integration methods with frequency dissipation for nonlinear structural applications","authors":"W. L. Fernandes, Gustavo Botelho Barbosa, M. Greco, R. Silveira","doi":"10.1590/1679-78256973","DOIUrl":"https://doi.org/10.1590/1679-78256973","url":null,"abstract":"The present paper aims to test recent (Truly self-starting two sub-step method and three-parameter single-step implicit method) and classical (Generalized-α, HHT - α, and WBZ - α methods) time integration methods using the geometrically nonlinear Positional Finite Element Method (PFEM). The numerical formulation is based on the total Lagrangian approach and uses the Hessian matrix to obtain the response. The mixed hardening inelastic model applied to PFEM is also presented. Two examples validate the time integration algorithms and the inelastic model. In the first example, the mixed hardening inelastic model is compared with the the bilinear stress-strain model and the elastic-perfectly plastic hinge model, and aspects such as amplitude decay and period elongation are discussed. In the second example, the implemented algorithms are verified in a severe geometrically nonlinear example, considering the influence of numerical dissipation, time interval, and the number of elements in the response. Results show the relevance of numerical damping for numerical stabilization and the good performance of the Generalized-α algorithm.","PeriodicalId":18192,"journal":{"name":"Latin American Journal of Solids and Structures","volume":"71 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67619839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"ERRATUM: Numerical evaluation of the seismic performance of thin reinforced concrete wall buildings representative of the industrialized building system","authors":"","doi":"10.1590/1679-78257045","DOIUrl":"https://doi.org/10.1590/1679-78257045","url":null,"abstract":"","PeriodicalId":18192,"journal":{"name":"Latin American Journal of Solids and Structures","volume":"1 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67620547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
: In the present research, the finite-element method (FEM) implemented in the ABAQUS software is used to evaluate several numerical models. This study presents a composite system of slit dampers coupled with column-attached seats, where excessive loading of the structural system leads to the yielding of the slit damper rather than damaging main structural elements, especially the beams. In this respect, four aspects of the behavior of such connections are herein investigated to come up with an in-depth insight; these include aspect ratio, distance ratio, compactness ratio
{"title":"Numerical Analysis of the Seismic Performance of Rigid Beam-To-Column Moment Connections Equipped with Steel Slit Damper (SSD)","authors":"M. Hosseini, Liao Haitao, I. Corbi, O. Corbi","doi":"10.1590/1679-78256994","DOIUrl":"https://doi.org/10.1590/1679-78256994","url":null,"abstract":": In the present research, the finite-element method (FEM) implemented in the ABAQUS software is used to evaluate several numerical models. This study presents a composite system of slit dampers coupled with column-attached seats, where excessive loading of the structural system leads to the yielding of the slit damper rather than damaging main structural elements, especially the beams. In this respect, four aspects of the behavior of such connections are herein investigated to come up with an in-depth insight; these include aspect ratio, distance ratio, compactness ratio","PeriodicalId":18192,"journal":{"name":"Latin American Journal of Solids and Structures","volume":"1 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67619685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiwu Zhou, Bo Wang, Xiaolu Deng, Jingdong Liu, Wen Zhang
In this paper, the ultra-high drop hammer impact test system is adopted for the vertical impact experiment on six SFSRCBs with steel fiber volume fraction of 2.0% and build the relevant numerical model. The research variables mainly include impact energy, impact mass and cumulative impact mode. The results show that, under a single equal energy impact, with the increase of the impact speed, the crack distribution of the specimen gradually tends to the mid-span local position. Compared with the impact mass, the impact speed has a greater effect on the failure mode, deformation resistance and deformation recovery ability of SFSRCBs. When the total cumulative impact energy is the same as the single impact energy, then the overall damage of the specimen caused by high-mass low-velocity cumulative impact is less significant than that caused by low-mass high-velocity cumulative impact. Combined with the finite element analysis, the calculation formula of the maximum deflection of SFSRCB under impact load is obtained. Finally, the calculation method of the impact damage evaluation factor of SFSRCBs is proposed.
{"title":"Mechanical Property Test and Damage Evaluation Analysis of Steel Fiber Stainless-Steel Reinforced Concrete Beams (SFSRCBs) under Impact Load","authors":"Xiwu Zhou, Bo Wang, Xiaolu Deng, Jingdong Liu, Wen Zhang","doi":"10.1590/1679-78257131","DOIUrl":"https://doi.org/10.1590/1679-78257131","url":null,"abstract":"In this paper, the ultra-high drop hammer impact test system is adopted for the vertical impact experiment on six SFSRCBs with steel fiber volume fraction of 2.0% and build the relevant numerical model. The research variables mainly include impact energy, impact mass and cumulative impact mode. The results show that, under a single equal energy impact, with the increase of the impact speed, the crack distribution of the specimen gradually tends to the mid-span local position. Compared with the impact mass, the impact speed has a greater effect on the failure mode, deformation resistance and deformation recovery ability of SFSRCBs. When the total cumulative impact energy is the same as the single impact energy, then the overall damage of the specimen caused by high-mass low-velocity cumulative impact is less significant than that caused by low-mass high-velocity cumulative impact. Combined with the finite element analysis, the calculation formula of the maximum deflection of SFSRCB under impact load is obtained. Finally, the calculation method of the impact damage evaluation factor of SFSRCBs is proposed.","PeriodicalId":18192,"journal":{"name":"Latin American Journal of Solids and Structures","volume":"13 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67620659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Using bonded piezoelectric transducers (PZT), this study evaluates damage to reinforced concrete beams at lap splices of tensile rebars. Four reinforced concrete beams with a span of 2700mm and a cross-section of 200 x 250mm were cast and simply edge-supported on roller supports 2250mm apart. In the zone of constant moment, the tensile reinforcements of the beams were spliced with varying lap lengths (10 ϕ , 20 ϕ , 30 ϕ and 40 ϕ ). Two PZT patches (one to operate as an actuator and the other as a receiver) were bonded on steel rebars and placed 50mm apart from their lapping edges. The wave propagation technique was used to record the signals experimentally, and the signals were processed further using wavelet packet analysis. By setting the time lag results of waves under pulse excitation, the damage of beams were identified. Damage indices were calculated based on the wavelet packet energy to ascertain the damage levels. The PZT was very sensitive to detect the pull-out bond failure and ductile flexural failure at the lap slices of steel rebars in the beam and it gives an advance indication before the structural collapse due to brittle failure.
{"title":"Damage Evaluation of Reinforced Concrete structures at lap splices of tensional steel bars using Bonded Piezoelectric Transducers","authors":"R. Regupathi, C. Jayaguru","doi":"10.1590/1679-78257069","DOIUrl":"https://doi.org/10.1590/1679-78257069","url":null,"abstract":"Using bonded piezoelectric transducers (PZT), this study evaluates damage to reinforced concrete beams at lap splices of tensile rebars. Four reinforced concrete beams with a span of 2700mm and a cross-section of 200 x 250mm were cast and simply edge-supported on roller supports 2250mm apart. In the zone of constant moment, the tensile reinforcements of the beams were spliced with varying lap lengths (10 ϕ , 20 ϕ , 30 ϕ and 40 ϕ ). Two PZT patches (one to operate as an actuator and the other as a receiver) were bonded on steel rebars and placed 50mm apart from their lapping edges. The wave propagation technique was used to record the signals experimentally, and the signals were processed further using wavelet packet analysis. By setting the time lag results of waves under pulse excitation, the damage of beams were identified. Damage indices were calculated based on the wavelet packet energy to ascertain the damage levels. The PZT was very sensitive to detect the pull-out bond failure and ductile flexural failure at the lap slices of steel rebars in the beam and it gives an advance indication before the structural collapse due to brittle failure.","PeriodicalId":18192,"journal":{"name":"Latin American Journal of Solids and Structures","volume":"1 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67620323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ana Waldila de Queiroz Ramiro Reis, R. Burgos, Maria Fernanda Figueiredo de Oliveira
Blast loads have been increasingly studied in the past decades, especially regarding civil structures. Until recently, the negative phase of these loads has been disregarded, but studies concluded that the effect of suction must be included. In the case of plates, nonlinearity plays an important role, and the membrane effect should also be considered. This work focuses on the influence of nonlinearity in plates subjected to blast loads. Equations were developed for the calculation of blast load parameters, considering that positive and negative phases are approximated by the Friedlander equation and cubic polynomial, respectively. The plate is modeled as a SDOF system using von Karman's theory of large displacements. The development of the nonlinear dynamic differential equation is reviewed, considering a simply supported plate, and its solution is based on fourth order Runge-Kutta numerical method. A reference example is used as a benchmark and then parametric studies are conducted, in which the influence of scaled distance, mass of explosive, and the consideration or not of the negative phase is analyzed.
{"title":"Nonlinear Dynamic Analysis of Plates Subjected to Explosive Loads","authors":"Ana Waldila de Queiroz Ramiro Reis, R. Burgos, Maria Fernanda Figueiredo de Oliveira","doi":"10.1590/1679-78256706","DOIUrl":"https://doi.org/10.1590/1679-78256706","url":null,"abstract":"Blast loads have been increasingly studied in the past decades, especially regarding civil structures. Until recently, the negative phase of these loads has been disregarded, but studies concluded that the effect of suction must be included. In the case of plates, nonlinearity plays an important role, and the membrane effect should also be considered. This work focuses on the influence of nonlinearity in plates subjected to blast loads. Equations were developed for the calculation of blast load parameters, considering that positive and negative phases are approximated by the Friedlander equation and cubic polynomial, respectively. The plate is modeled as a SDOF system using von Karman's theory of large displacements. The development of the nonlinear dynamic differential equation is reviewed, considering a simply supported plate, and its solution is based on fourth order Runge-Kutta numerical method. A reference example is used as a benchmark and then parametric studies are conducted, in which the influence of scaled distance, mass of explosive, and the consideration or not of the negative phase is analyzed.","PeriodicalId":18192,"journal":{"name":"Latin American Journal of Solids and Structures","volume":"1 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67619105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To evaluate the fatigue life of Q420C steel welded joints, fatigue tests were performed on butt-welded joints, cross-butt-welded joints and cross-fillet-welded joints. The fatigue strength S-N curves of the joints were fitted. Then the formation and development of fatigue cracks were analyzed by fracture morphology. The fatigue properties of joints were compared with literature data and standard curves. The results showed that the fatigue test data of the three types of welded joints were roughly above the standard curves. Moreover, the fatigue strength of butt-welded joint was significantly higher than the calculated values of standards, indicating a large safety margin. The test value of cross-butt-welded joint was close to the calculated values of standards, so it is suggested to moderately reduce the standard values. In addition, all the three standards could well predict the fatigue life of cross-fillet-welded joint. The fracture morphology of the specimens showed the development process of fatigue damage, and the fatigue displacement curve and damage curve proved the formation of the fatigue fracture in specimens.
{"title":"Experimental study on fatigue properties of Q420C steel welded joints at room temperature","authors":"Liguo Yang, Y. Xing","doi":"10.1590/1679-78256808","DOIUrl":"https://doi.org/10.1590/1679-78256808","url":null,"abstract":"To evaluate the fatigue life of Q420C steel welded joints, fatigue tests were performed on butt-welded joints, cross-butt-welded joints and cross-fillet-welded joints. The fatigue strength S-N curves of the joints were fitted. Then the formation and development of fatigue cracks were analyzed by fracture morphology. The fatigue properties of joints were compared with literature data and standard curves. The results showed that the fatigue test data of the three types of welded joints were roughly above the standard curves. Moreover, the fatigue strength of butt-welded joint was significantly higher than the calculated values of standards, indicating a large safety margin. The test value of cross-butt-welded joint was close to the calculated values of standards, so it is suggested to moderately reduce the standard values. In addition, all the three standards could well predict the fatigue life of cross-fillet-welded joint. The fracture morphology of the specimens showed the development process of fatigue damage, and the fatigue displacement curve and damage curve proved the formation of the fatigue fracture in specimens.","PeriodicalId":18192,"journal":{"name":"Latin American Journal of Solids and Structures","volume":"1 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67619177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Z. Xiong, Jiawen Li, Hou Zhu, Xuyao Liu, Zhuoxi Liang
This paper has evaluated the bending performance of a novel prefabricated MVFT steel-concrete composite girder. 9 meters pilot MVFT girder was analyzed by validated finite element model. In the pilot test, the height of web, the length of grouted concrete in the girder and net spacing between webs were parametrically modeled to discuss their effect to the bending strength. An ultimate bending strength formula has been obtained, which was based on the regression of parametric results. In the meantime, the two Machine Learning (ML) models, BP neural network and Least Squares Support Vector Machine, have been also implemented to train and then predict the ultimate strength of MVFT girder. Three factors were selected as input in ML models: the distance between steel girder’s Tensile Centroid(TC) and slab’s Compressive Centroid(CC), the distance between steel girder’s TC and its CC, the compressive area of steel girder. After the completion of the ML training, the ultimate strength predictions of 30 meters MVFT girder by BP model and the formula have been compared, which agrees well with each other and validates their accuracy.
{"title":"Ultimate Bending Strength Evaluation of MVFT Composite Girder by using Finite Element Method and Machine Learning Regressors","authors":"Z. Xiong, Jiawen Li, Hou Zhu, Xuyao Liu, Zhuoxi Liang","doi":"10.1590/1679-78257006","DOIUrl":"https://doi.org/10.1590/1679-78257006","url":null,"abstract":"This paper has evaluated the bending performance of a novel prefabricated MVFT steel-concrete composite girder. 9 meters pilot MVFT girder was analyzed by validated finite element model. In the pilot test, the height of web, the length of grouted concrete in the girder and net spacing between webs were parametrically modeled to discuss their effect to the bending strength. An ultimate bending strength formula has been obtained, which was based on the regression of parametric results. In the meantime, the two Machine Learning (ML) models, BP neural network and Least Squares Support Vector Machine, have been also implemented to train and then predict the ultimate strength of MVFT girder. Three factors were selected as input in ML models: the distance between steel girder’s Tensile Centroid(TC) and slab’s Compressive Centroid(CC), the distance between steel girder’s TC and its CC, the compressive area of steel girder. After the completion of the ML training, the ultimate strength predictions of 30 meters MVFT girder by BP model and the formula have been compared, which agrees well with each other and validates their accuracy.","PeriodicalId":18192,"journal":{"name":"Latin American Journal of Solids and Structures","volume":"1 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67619733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Altheeb, Ibrahim M. H. Alshaikh, A. Abadel, M. Nehdi, Hussam Alghamdi
This study aims to investigate the effect of the infilled frames through various important parameters (i.e., the openings’ percentage in infill walls several columns on the first floor are removed partial infilled) in the RC structures, subject to progressive collapse scenarios. To this end, 3D finite element models were constructed by using the software ABAQUS. Numerical and experimental results were compared to substantiate the finite element models’ capability of simulating the experimental models’ behavior of Al-Chaar et al. (2002) in an accurate manner. The results showed that there was good agreement between experimental and numerical results. Moreover, the results indicated that there was a significant effect, which cannot be neglected, on the progressive collapse resistance; the reduction ratios in vertical displacement at the regions removed columns can reach up to 80%.
{"title":"Effects of Non-Structural Walls on Mitigating the Risk of Progressive Collapse of RC Structures","authors":"A. Altheeb, Ibrahim M. H. Alshaikh, A. Abadel, M. Nehdi, Hussam Alghamdi","doi":"10.1590/1679-78257023","DOIUrl":"https://doi.org/10.1590/1679-78257023","url":null,"abstract":"This study aims to investigate the effect of the infilled frames through various important parameters (i.e., the openings’ percentage in infill walls several columns on the first floor are removed partial infilled) in the RC structures, subject to progressive collapse scenarios. To this end, 3D finite element models were constructed by using the software ABAQUS. Numerical and experimental results were compared to substantiate the finite element models’ capability of simulating the experimental models’ behavior of Al-Chaar et al. (2002) in an accurate manner. The results showed that there was good agreement between experimental and numerical results. Moreover, the results indicated that there was a significant effect, which cannot be neglected, on the progressive collapse resistance; the reduction ratios in vertical displacement at the regions removed columns can reach up to 80%.","PeriodicalId":18192,"journal":{"name":"Latin American Journal of Solids and Structures","volume":"1 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67620423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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