期刊：
European Journal of Education,2025年60(2):e70078 ISSN：0141-8211
通讯作者：
Qian Wang
作者机构：
[Qian Wang; Shiwang Hou; Sixian Wan] School of Advanced Interdisciplinary Studies, Hunan University of Technology and Business, Changsha, People's Republic of China;[Xin Feng] School of Civil Engineering, Central South University of Forestry and Technology, Changsha, People's Republic of China;[Hao Feng] Engineering Department, Country Garden Group, Foshan, People's Republic of China
通讯机构：
[Qian Wang] S;School of Advanced Interdisciplinary Studies, Hunan University of Technology and Business, Changsha, People's Republic of China
摘要：
To prepare undergraduates for complex careers, interdisciplinary higher education is gaining popularity. However, implementing interdisciplinary learning in engineering management is challenging due to the complex and intertwined knowledge structures. While smart education platforms provide access to extensive knowledge bases, the intricate web of relationships can overwhelm undergraduates. Therefore, innovative technologies are needed to create a coherent knowledge system. Knowledge graphs, derived from artificial intelligence, are pivotal tools for connecting knowledge points across courses. This study begins by explaining the necessity of constructing interdisciplinary knowledge graphs. It then uses engineering management as a case study to outline a strategic framework for developing a knowledge graph. Finally, it analyses the benefits and challenges of applying knowledge graphs in interdisciplinary higher education.
摘要：
The research aimed at evaluating the creep properties of glulam beams connected with steel joining plates and bolts (GBSBs) made of Larix gmelinii. Three GBSBs and three intact Glulam beams of identical dimensions were subjected to long-term service loads, with their mid-span deflection behavior monitored and analyzed to understand the creep mechanisms and material performance impacts over an extended period. After 900 days of loading, the average mid-span deflection of the intact Glulam beams and the GBSBs were 18.55 mm and 27.70 mm, respectively. Three existing creep models and a modified Burger model were adopted to fit the long-term deflection curves of the specimens. The modified Burger model provided satisfactory accuracy capturing the trend of creep behavior and demonstrated superior capability in predicting the trend throughout the service life period. It was also found that the elastic deformation emerged as the main deformation form within the beams, and the viscoelastic deformation may potentially govern the deformation. Additionally, theoretical calculations of the long-term deformation using the timber long-term deformation calculation method specified in Eurocode 5 were conducted. These results are in good agreement with the calculation results according to Eurocode 5.
The research aimed at evaluating the creep properties of glulam beams connected with steel joining plates and bolts (GBSBs) made of Larix gmelinii. Three GBSBs and three intact Glulam beams of identical dimensions were subjected to long-term service loads, with their mid-span deflection behavior monitored and analyzed to understand the creep mechanisms and material performance impacts over an extended period. After 900 days of loading, the average mid-span deflection of the intact Glulam beams and the GBSBs were 18.55 mm and 27.70 mm, respectively. Three existing creep models and a modified Burger model were adopted to fit the long-term deflection curves of the specimens. The modified Burger model provided satisfactory accuracy capturing the trend of creep behavior and demonstrated superior capability in predicting the trend throughout the service life period. It was also found that the elastic deformation emerged as the main deformation form within the beams, and the viscoelastic deformation may potentially govern the deformation. Additionally, theoretical calculations of the long-term deformation using the timber long-term deformation calculation method specified in Eurocode 5 were conducted. These results are in good agreement with the calculation results according to Eurocode 5.
通讯机构：
[Wang, HD ] C;Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha 410004, Peoples R China.
关键词：
Calcareous sand;EICP;Stress-strain curve;Calcium carbonate content;Statistical damage constitutive model
摘要：
The enzyme-induced calcium carbonate precipitation (EICP) technique was utilized to cement calcareous sand. The mechanical properties of EICP-cemented calcareous sand at various cementation degree were investigated using consolidated drained triaxial compression tests. A statistical damage constitutive model tailored for EICP-cemented calcareous sand was also developed based on damage mechanics theory. The findings are as follows: (1) The EICP technique significantly enhances the cementation of calcareous sand. As the number of grouting operations increases, the peak deviator stress of the cemented material gradually increases, with the maximum enhancement approaching 2.5 times. Moreover, during the stress decay phase following the peak stress, the decay rate of the cemented sand accelerates, displaying a more pronounced brittle characteristic. (2) With the increased calcium carbonate content, the peak eccentric stress of the cemented body increases significantly, and there is an obvious nonlinear exponential correlation between them. (3) The statistical damage constitutive model, formulated based on Lemaitre's strain equivalence principle combined with a log-normal distribution and the Drucker–Prager strength criterion, accurately predicts the stress–strain curves, effectively simulating the complete stress–strain evolution of EICP-cemented sand under different numbers of grouting operations and varied confining pressure conditions. (4) At higher cementation levels or lower confining pressures, the internal damage process of the EICP-cemented calcareous sand specimens intensifies, indicated by the rapid increase of the damage variable D with axial strain. The research findings can provide a crucial theoretical foundation for the application of EICP technology in the treatment of island reef or roadbed foundations, aiding in the analysis and prediction of the mechanical properties of EICP-cemented calcareous sands.
作者机构：
[Xueqi Li; Yong Cai; Haijun Chen] School of Civil Engineering, Central South University, Changsha 410075, China;[Xiaoyong Lv] School of Civil Engineering, Central South University of Forestry and Technology, Changsha 410004, China
通讯机构：
[Yong Cai] S;School of Civil Engineering, Central South University, Changsha 410075, China
摘要：
In research on using vehicles to extract bridge frequencies, single degree-of-freedom vehicles and two-dimensional bridges cannot fully simulate vehicle-bridge interaction and bridge frequency extraction. Therefore, a method of using two-axle vehicles to extract the vertical and flexural-torsional frequencies of three-dimensional (3D) bridges is proposed. First, the feasibility of this method is theoretically verified by analytical methods. Subsequently, a signal enhancement approach, combining successive variational mode decomposition (SVMD) and a designed window function, is proposed. SVMD performs modal decomposition on vehicle signals, while the window function reduces noise in vehicle signals and enhances bridge signals, resulting in a low-noise spectrum. The investigations indicate that bridge frequencies extracted by the proposed method exhibit a relative error of <5 %, which meets engineering requirements. Moreover, the method is insensitive to vehicle parameters and is not limited by two-axle vehicle types. Notably, vertical acceleration spectra of two-axle vehicles, filtered using the signal enhancement approach, can resist the effect of road roughness noise on bridge frequency identification. This study further advances the vehicle scanning method and offers a practical approach to bridge health monitoring.
In research on using vehicles to extract bridge frequencies, single degree-of-freedom vehicles and two-dimensional bridges cannot fully simulate vehicle-bridge interaction and bridge frequency extraction. Therefore, a method of using two-axle vehicles to extract the vertical and flexural-torsional frequencies of three-dimensional (3D) bridges is proposed. First, the feasibility of this method is theoretically verified by analytical methods. Subsequently, a signal enhancement approach, combining successive variational mode decomposition (SVMD) and a designed window function, is proposed. SVMD performs modal decomposition on vehicle signals, while the window function reduces noise in vehicle signals and enhances bridge signals, resulting in a low-noise spectrum. The investigations indicate that bridge frequencies extracted by the proposed method exhibit a relative error of <5 %, which meets engineering requirements. Moreover, the method is insensitive to vehicle parameters and is not limited by two-axle vehicle types. Notably, vertical acceleration spectra of two-axle vehicles, filtered using the signal enhancement approach, can resist the effect of road roughness noise on bridge frequency identification. This study further advances the vehicle scanning method and offers a practical approach to bridge health monitoring.
作者机构：
[Chen, Ying; Huang, Jingxiang; Cheng, Xiang; Liu, Lei; Wang, Shuaifeng; Liu, Peng] Cent South Univ, Sch Civil Engn, Changsha 410000, Peoples R China.;[Huang, Jingxiang; Cheng, Xiang; Liu, Lei; Yu, Zhiwu; Wang, Shuaifeng; Liu, Peng] Natl Engn Res Ctr High Speed Railway Construct, Changsha 410000, Peoples R China.;[Li, Qizhi; Shao, Guangqiang] China Construct Second Engn Bur Ltd, Beijing 100160, Peoples R China.;[Yu, Zhiwu; Liu, Peng] China Railway Grp Ltd, Beijing 100039, Peoples R China.;[Wang, Lingling] Guizhou Univ, Sch Civil Engn, Guiyang 550025, Peoples R China.
通讯机构：
[Liu, P ] C;Cent South Univ, Sch Civil Engn, Changsha 410000, Peoples R China.;Natl Engn Res Ctr High Speed Railway Construct, Changsha 410000, Peoples R China.;China Railway Grp Ltd, Beijing 100039, Peoples R China.
摘要：
The effects of high-temperature modified phosphogypsum (HPG), incorporated at contents of 40%, 50%, and 60%, on the compressive strength and elastic modulus of mortar and concrete were investigated. Additionally, the influence of graded granulated blast furnace slag powder (GGBS), quicklime, and silica fume on the mechanical properties of HPG-based mortar (HPGM) and HPG-based concrete (HPGC) was discussed. Moreover, the microstructure of HPGM was analyzed using scanning electron microscopy (SEM). A two-dimensional mesoscale model of HPGC was developed to predict how variations in HPG content, coarse aggregate characteristics, and interfacial transition zone (ITZ) characteristics influence the compressive strength and elastic modulus of HPGC. The experimental results showed that high volumes of HPG weakened the mechanical properties of HPGM and HPGC, while appropriate amounts of mineral admixtures offset the negative effects caused by calcium hydroxide (Ca(OH)2) crystals and impurities within the system. The simulation results indicated that the maximum deviation between the mesoscale model prediction and experimental data was only 8.38%, which verified the accuracy of the mesoscale model prediction. The compressive strength of HPGC initially decreased and subsequently increased with the rise in the modulus and content of coarse aggregate, whereas it declined with higher HPG dosage and increased ITZ thickness. In contrast, the elastic modulus of HPGC showed a gradual increase with rising coarse aggregate content and improved ITZ mechanical properties, while it decreased as HPG content and ITZ thickness increased.
摘要：
This study investigates the identification method of bridge modal frequencies from contact responses of a single degree-of-freedom vehicle. To begin with, a test vehicle and a bridge are modeled as a single degree-of-freedom (DOF) vehicle model and a three-dimensional beam model respectively. Subsequently, close-form solutions for bridge displacements and contact responses are derived based on integral transform. And then, a vehicle-bridge interaction model is established by the finite element method to verify the close-form solutions. Remarkably, this model considered the stochastic velocities and initial vibration of vehicles as well as the flexural-torsional vibration of bridges with pavement roughness. Finally, the effect of vehicle initial vibrations, stochastic vehicle velocities, vehicle weights, pavement roughness and the flexural-torsional vibration of bridges on the bridge modal frequency identification is investigated. Investigations reveal that the proposed method presents good robustness against the vehicle initial vibration, the vehicle weight and the pavement roughness. Moreover, identification method of bridge modal frequencies is sensitive to the stochastic vehicle velocities, and the optimal velocity is 5–9 m/s with a velocity stochastic fluctuation of 1–2 m/s. In addition, the effect of flexural-torsional vibration of bridges on contact responses cannot be neglected and flexural-torsional vibration of bridges is beneficial to identify higher bridge modal frequencies.
This study investigates the identification method of bridge modal frequencies from contact responses of a single degree-of-freedom vehicle. To begin with, a test vehicle and a bridge are modeled as a single degree-of-freedom (DOF) vehicle model and a three-dimensional beam model respectively. Subsequently, close-form solutions for bridge displacements and contact responses are derived based on integral transform. And then, a vehicle-bridge interaction model is established by the finite element method to verify the close-form solutions. Remarkably, this model considered the stochastic velocities and initial vibration of vehicles as well as the flexural-torsional vibration of bridges with pavement roughness. Finally, the effect of vehicle initial vibrations, stochastic vehicle velocities, vehicle weights, pavement roughness and the flexural-torsional vibration of bridges on the bridge modal frequency identification is investigated. Investigations reveal that the proposed method presents good robustness against the vehicle initial vibration, the vehicle weight and the pavement roughness. Moreover, identification method of bridge modal frequencies is sensitive to the stochastic vehicle velocities, and the optimal velocity is 5–9 m/s with a velocity stochastic fluctuation of 1–2 m/s. In addition, the effect of flexural-torsional vibration of bridges on contact responses cannot be neglected and flexural-torsional vibration of bridges is beneficial to identify higher bridge modal frequencies.
摘要：
Based on the elaborate 3D solid finite element (FE) model established by ABAQUS software, a pseudo-static analysis was conducted on a special-shaped concrete-filled steel tubular column composite frame structure. The FE model considers the confinement effect of both the steel tubes and the tensile bars exerting on the core concrete. The results of the numerical analysis concerning failure modes, load-displacement hysteretic curves, load-displacement skeleton curves and stiffness degradation-displacement curves demonstrate a strong correlation with the existing quasi-static test data. Furthermore, an in-depth analysis was conducted on the impact of the axial compression ratio of column on the plastic energy dissipation distribution mechanism. With an axial compression ratio of the column ranging from 0.1 to 0.55, the composite frame structure primarily relies on the energy dissipation of beams, while the columns serve as supplementary support, thereby exemplifying the principle of "strong column-weak beam." As the axial compression ratio rises to the range of 0.6-0.8, the composite frame structure transitions a "strong beam-weak column" structural system. Combined with the longitudinal compressive strain of the steel tube at the bottom of the column, a quantitative evaluation method for seismic damage is proposed, grounded in indexes of "stiffness damage" and "energy damage." Then, the threshold values of energy damage and stiffness damage are determined across four distinct levels: "elastic stage in small earthquake," "elasto-plastic stage in medium earthquake," "plastic stage in heavy earthquake" and "failure stage." The proposed method effectively evaluate the damage severity of special-shaped CFT column composite frame structure subjected to seismic events.
摘要：
Enzyme-induced carbonate precipitation (EICP) technology was used to cement calcareous sand. Consolidated drained triaxial compression tests were conducted to investigate the mechanical properties of EICP-cemented calcareous sand (EICP-S) and EICP-cemented calcareous sand mixed with coir fiber (EICP-FS) under varying levels of cementation and confining pressures. Based on the stress-strain curves, a brittleness evaluation index ( B EICP ) suitable for cemented calcareous sand was developed. The research results indicate: (1) The EICP technique exhibits a pronounced cementation effect on calcareous sand. With the number of grouting operations escalating from 1 to 9, or the confining pressure incrementing from 100 kPa to 300 kPa, the peak deviatoric stress of the cemented mass progressively improves. Furthermore, the EICP-FS specimens display a higher strain at failure and demonstrate a more gradual post-peak stress reduction characteristic. (2) At low cementation levels, coir fiber can effectively enhance the peak deviatoric stress of the samples. However, the enhancement effect diminishes at high cementation levels, and the peak deviatoric stress of the EICP-FS samples can even be lower than that of the EICP-S samples without fiber. (3) At low cementation levels, coir fiber can effectively mitigate the post-peak strength loss of the cemented body. However, this mitigating effect diminishes at high cementation levels. (4) Parameters such as the pre-peak elastic energy ratio, failure strain, maximum post-peak average modulus, peak deviatoric stress, and residual stress of the cemented calcareous sand highly correlate with its brittleness characteristics. The brittleness evaluation index ( B EICP ) constructed based on these parameters can effectively evaluate its brittleness properties. (5) Under different confining pressures, the B EICP of EICP-FS samples is generally lower than that of EICP-S samples. However, under higher confining pressure conditions, the B EICP values of both types of samples are similar. The research results can provide a theoretical basis for a deeper understanding of the brittleness characteristics of calcareous sand treated with EICP technology and can serve as a reference for brittleness evaluation in related engineering applications.
Enzyme-induced carbonate precipitation (EICP) technology was used to cement calcareous sand. Consolidated drained triaxial compression tests were conducted to investigate the mechanical properties of EICP-cemented calcareous sand (EICP-S) and EICP-cemented calcareous sand mixed with coir fiber (EICP-FS) under varying levels of cementation and confining pressures. Based on the stress-strain curves, a brittleness evaluation index ( B EICP ) suitable for cemented calcareous sand was developed. The research results indicate: (1) The EICP technique exhibits a pronounced cementation effect on calcareous sand. With the number of grouting operations escalating from 1 to 9, or the confining pressure incrementing from 100 kPa to 300 kPa, the peak deviatoric stress of the cemented mass progressively improves. Furthermore, the EICP-FS specimens display a higher strain at failure and demonstrate a more gradual post-peak stress reduction characteristic. (2) At low cementation levels, coir fiber can effectively enhance the peak deviatoric stress of the samples. However, the enhancement effect diminishes at high cementation levels, and the peak deviatoric stress of the EICP-FS samples can even be lower than that of the EICP-S samples without fiber. (3) At low cementation levels, coir fiber can effectively mitigate the post-peak strength loss of the cemented body. However, this mitigating effect diminishes at high cementation levels. (4) Parameters such as the pre-peak elastic energy ratio, failure strain, maximum post-peak average modulus, peak deviatoric stress, and residual stress of the cemented calcareous sand highly correlate with its brittleness characteristics. The brittleness evaluation index ( B EICP ) constructed based on these parameters can effectively evaluate its brittleness properties. (5) Under different confining pressures, the B EICP of EICP-FS samples is generally lower than that of EICP-S samples. However, under higher confining pressure conditions, the B EICP values of both types of samples are similar. The research results can provide a theoretical basis for a deeper understanding of the brittleness characteristics of calcareous sand treated with EICP technology and can serve as a reference for brittleness evaluation in related engineering applications.
期刊：
Journal of Building Engineering,2025年102:112003 ISSN：2352-7102
通讯作者：
Yin, J
作者机构：
[Yin, Jian; Yin, J; Lv, Xiaoyong] Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha 410004, Peoples R China.;[Liu, Peng; Yu, Zhiwu] Cent South Univ, Sch Civil Engn, Changsha 410075, Peoples R China.
通讯机构：
[Yin, J ] C;Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha 410004, Peoples R China.
关键词：
Prefabricated element precast concrete frame;Innovative assembling pattern;Experimental research;Seismic performance;Restoring force model
摘要：
Prefabricated concrete (PC) frame structures have been widely applied in recent years for numerous advantages, but there are still problems such as the structural integrity and seismic performance may be weakened due to some connection positions are arranged in areas with high force. Therefore, a novel prefabricated element precast concrete frame (PEPCF) is proposed in this study, and the corresponding connection positions are optimized to enhance the seismic behaviour. A comparative quasi-static cyclic experimental research is performed on the seismic behaviour of two novel PEPCFs with different beam connection locations and a conventional cast-in-place (CIP) frame. The rationality of the innovative assembly pattern for the PEPCFs is verified, and it is proven to be beneficial for seismic resistance. The test findings reveal that the PEPCFs demonstrate good seismic performance, and that they outperform the CIP frame from the perspective of 3.41 %–5.68 % higher load bearing capacity, 38.19 %–41.75 % greater ductility and 45.09 %–58.38 % superior secant stiffness at yield point. Furthermore, it is concluded that the novel PEPCFs of which the beam connection location is 1.5 h ( h is the beam height) from the beam end has slightly improved seismic performance in terms of 2.20 % higher load bearing capacity and 2.58 % greater ductility, compared with the beam connection location was 1.0 h from the beam end, and this may be attributed to the connection position which is relatively farther from the plastic hinge areas. Then, the restoring force model (RFM) of the novel PEPCFs is established and verified on the base of the experimental results. It suggests that the established four-linear RFM with stiffness and strength deterioration as well as pinching effect can predict the hysteretic behaviours of the novel PEPCFs. Therefore, the results of this study can provide valuable insights and technical guidance for promoting the transformation and upgrading of traditional construction industry and the development of PC structures.
Prefabricated concrete (PC) frame structures have been widely applied in recent years for numerous advantages, but there are still problems such as the structural integrity and seismic performance may be weakened due to some connection positions are arranged in areas with high force. Therefore, a novel prefabricated element precast concrete frame (PEPCF) is proposed in this study, and the corresponding connection positions are optimized to enhance the seismic behaviour. A comparative quasi-static cyclic experimental research is performed on the seismic behaviour of two novel PEPCFs with different beam connection locations and a conventional cast-in-place (CIP) frame. The rationality of the innovative assembly pattern for the PEPCFs is verified, and it is proven to be beneficial for seismic resistance. The test findings reveal that the PEPCFs demonstrate good seismic performance, and that they outperform the CIP frame from the perspective of 3.41 %–5.68 % higher load bearing capacity, 38.19 %–41.75 % greater ductility and 45.09 %–58.38 % superior secant stiffness at yield point. Furthermore, it is concluded that the novel PEPCFs of which the beam connection location is 1.5 h ( h is the beam height) from the beam end has slightly improved seismic performance in terms of 2.20 % higher load bearing capacity and 2.58 % greater ductility, compared with the beam connection location was 1.0 h from the beam end, and this may be attributed to the connection position which is relatively farther from the plastic hinge areas. Then, the restoring force model (RFM) of the novel PEPCFs is established and verified on the base of the experimental results. It suggests that the established four-linear RFM with stiffness and strength deterioration as well as pinching effect can predict the hysteretic behaviours of the novel PEPCFs. Therefore, the results of this study can provide valuable insights and technical guidance for promoting the transformation and upgrading of traditional construction industry and the development of PC structures.
期刊：
International Journal of Adhesion and Adhesives,2025年139:103974 ISSN：0143-7496
通讯作者：
Liu, KF
作者机构：
[Liu, Kefei; Liu, KF; Li, Quan; Li, Teng] Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha 410004, Hunan, Peoples R China.;[Jiang, Kang] Hunan Commun Res Inst Co Ltd, Changsha 410015, Peoples R China.;[Li, Quan] Hunan Prov Engn Res Ctr Construct Solid Wastes Rec, Changsha 410205, Peoples R China.
通讯机构：
[Liu, KF ] C;Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha 410004, Hunan, Peoples R China.
关键词：
GO modified asphalt;Carbonyl group;Fourier transform infrared spectroscopy;Thermal-oxidative aging;Aging property
摘要：
The fundamental reason why thermal-oxidative aging can greatly affect the physical properties, mechanical properties, rheological properties and durability of asphalt is that the molecular structure and colloidal structure of asphalt are changed due to volatilization, oxidation and spatial hardening. To study the possible chemical changes of graphene oxide (GO) modified asphalt after aging and reveal its action mechanism, this study analyzed how GO changes the process of thermal-oxidative aging of asphalt from the perspective of molecular structure, and evaluated the aging properties of GO modified asphalt by testing the content change of each characteristic functional group in asphalt after thermal-oxidative aging. The results show that GO can significantly increase the content of amide groups (0.0018 %) in the base asphalt, which in turn enhances the adhesion and toughness of asphalt, reduces the brittleness of asphalt and improves the bearing strength. The addition of GO effectively inhibited the increase of carboxylic acid and ketone content in asphalt caused by aging. Amide is the aging product of asphalt exposed to air, and the presence of amide promotes the formation of hydrogen bonds, which is more conducive to the miscibility of GO and asphalt. The modification effect of GO on base asphalt is better than SBS-modified asphalt. The results of AFM show that GO-modified asphalt has a better proportion of components and a more stable colloidal structure, and the adhesion performance of GO-modified asphalt is significantly improved. GO can obviously improve the aging resistance and slow down the aging rate of asphalt, indicating that GO can improve the pavement performance and extend the service life of asphalt pavement.
The fundamental reason why thermal-oxidative aging can greatly affect the physical properties, mechanical properties, rheological properties and durability of asphalt is that the molecular structure and colloidal structure of asphalt are changed due to volatilization, oxidation and spatial hardening. To study the possible chemical changes of graphene oxide (GO) modified asphalt after aging and reveal its action mechanism, this study analyzed how GO changes the process of thermal-oxidative aging of asphalt from the perspective of molecular structure, and evaluated the aging properties of GO modified asphalt by testing the content change of each characteristic functional group in asphalt after thermal-oxidative aging. The results show that GO can significantly increase the content of amide groups (0.0018 %) in the base asphalt, which in turn enhances the adhesion and toughness of asphalt, reduces the brittleness of asphalt and improves the bearing strength. The addition of GO effectively inhibited the increase of carboxylic acid and ketone content in asphalt caused by aging. Amide is the aging product of asphalt exposed to air, and the presence of amide promotes the formation of hydrogen bonds, which is more conducive to the miscibility of GO and asphalt. The modification effect of GO on base asphalt is better than SBS-modified asphalt. The results of AFM show that GO-modified asphalt has a better proportion of components and a more stable colloidal structure, and the adhesion performance of GO-modified asphalt is significantly improved. GO can obviously improve the aging resistance and slow down the aging rate of asphalt, indicating that GO can improve the pavement performance and extend the service life of asphalt pavement.
作者机构：
[Zhang, Jiayang; Liu, Jian; Wang, Lei] Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha 410004, Peoples R China.;[Zhang, Jiayang] JSTI Grp, Nanjing 210019, Peoples R China.
通讯机构：
[Liu, J ] C;Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha 410004, Peoples R China.
关键词：
improved power spectral model;high-intensity rare earthquake;random seismic response analysis;finite element model
摘要：
To study the influence of random seismic responses on the structure of a large-span double-deck steel truss cable-stayed bridges under the effects of high-intensity rare earthquakes, a new power spectral model was proposed based on improvements to existing power spectra for fitting the improved power spectra of random seismic responses. The bridge finite element model established using ANSYS was employed as an engineering example for computational analysis to investigate whether the improved spectrum exhibited better adaptability and feasibility under high-intensity rare earthquake compared with other power spectra. The results indicated that the power spectral model, based on improvements to the original power spectra, had a more pronounced filtering effect on the low-frequency and high-frequency portions. Moreover, under the consistent three-dimensional excitation, the vertical displacement of the main beam was the greatest, indicating that the improved spectrum had better adaptability than other power spectra in studying the high-intensity rare earthquakes affecting bridges. It also reflected the feasibility of using the improved spectrum for studying the random responses to high-intensity rare earthquakes, providing a reference for bridge design concerning rare earthquakes in large-span bridges.
摘要：
In dynamic analysis, the load of a maglev train is often simplified to a uniformly distributed load, and its speed is not always constant. Owing to the non-coincidence of the shear center and centroid in the thin-walled beam that bears the train, complex bending-torsional coupling vibrations often occur under dynamic loads, which can affect the bridge safety. In light of this, analytical solutions are proposed in this study to obtain the spatial vibration responses of thin-walled beams subjected to uniformly distributed moving loads with variable speeds. By employing Vlasov beam theory and considering the influence of additional torque, the governing equations of the beam are established. Fourier integral transforms and Laplace transforms are jointly applied to decouple the equations, thereby obtaining analytical solutions for the beam's response in vertical, lateral, and torsional directions. To validate the proposed method, this study firstly compares the results with finite element method (FEM) under three distinct operational scenarios: accelerated loading, decelerated loading, and constant speed loading. Compared with the Newmark-β method and the precise integration method (PIM), the analytical solutions proposed have significant advantages in terms of fast computation speed and high accuracy. Parametric analysis shows that the beam's lateral vibration is more sensitive to initial speed and acceleration than vertical vibration, and deceleration of the load can cause a lag in the occurrence of maximum lateral response. As the span grows from 16 m to 48 m, the bending-torsional coupling effect is reduced, with the maximum bending-torsional moment dropping by about 49 % at midspan.
In dynamic analysis, the load of a maglev train is often simplified to a uniformly distributed load, and its speed is not always constant. Owing to the non-coincidence of the shear center and centroid in the thin-walled beam that bears the train, complex bending-torsional coupling vibrations often occur under dynamic loads, which can affect the bridge safety. In light of this, analytical solutions are proposed in this study to obtain the spatial vibration responses of thin-walled beams subjected to uniformly distributed moving loads with variable speeds. By employing Vlasov beam theory and considering the influence of additional torque, the governing equations of the beam are established. Fourier integral transforms and Laplace transforms are jointly applied to decouple the equations, thereby obtaining analytical solutions for the beam's response in vertical, lateral, and torsional directions. To validate the proposed method, this study firstly compares the results with finite element method (FEM) under three distinct operational scenarios: accelerated loading, decelerated loading, and constant speed loading. Compared with the Newmark-β method and the precise integration method (PIM), the analytical solutions proposed have significant advantages in terms of fast computation speed and high accuracy. Parametric analysis shows that the beam's lateral vibration is more sensitive to initial speed and acceleration than vertical vibration, and deceleration of the load can cause a lag in the occurrence of maximum lateral response. As the span grows from 16 m to 48 m, the bending-torsional coupling effect is reduced, with the maximum bending-torsional moment dropping by about 49 % at midspan.
摘要：
Timely and effective detection of surface defects on bridges is crucial for ensuring public transportation safety and extending the lifespan of bridges. Traditional bridge defect detection primarily relies on manual inspections, which are highly subjective, inefficient, and exhibit a significant rate of undetected issues. Moreover, there is a lack of effective detection methods for bridges located in special areas, such as large-span canyon bridges. To address these challenges, this study focuses on the Chishi Bridge in Chenzhou, Hunan Province, China, which is the largest multi-tower concrete cable-stayed bridge in the world with high piers. First, we designed a fully automated detection system for one-stop intelligent maintenance operations. Second, our system integrates a bridge damage detection algorithm guided by fractal geometric features. This algorithm is an improvement based on the classic object detection algorithm YOLOv7 (You Only Look Once), incorporating the SimAM and CARAFE attention mechanisms to enhance damage feature recognition, accurately identifying and assessing various defects on the underside of the bridge. The proposed method achieves an average mean precision (mAP) of 87.24% and reduces inference time by 15%, demonstrating significant improvements in both accuracy and efficiency compared to the baseline. Overall, this significantly enhances the level of intelligent defect detection for the Chishi Bridge, ensuring safe and stable operation while showcasing considerable economic production value.
摘要：
To consider the highly nonlinear and complex buckling behaviour of various sections of cold-formed steel (CFS) built-up columns, experimental and finite element (FE) methods are commonly used for calculating their axial compressive capacity, although these methods are time-consuming and costly. This paper proposes machine learning (ML) methods to overcome the issues of traditional methods for predicting the maximum axial load capacity (MALC) of CFS built-up columns. A total of 3839 samples from more than 33 different types of sections were collected from 43 published papers, including 817 experimental data and 3,022 FE simulation data. A total of 15 characteristic parameters, such as the second moment of area, the radius of gyration, and the polar second moment of area, are considered when nine different ML models are trained. The robustness of these models was compared via the Monte Carlo simulation method, and the predicted results were compared with the calculated results from the current codes. The results show that the extreme gradient boosting (XGB) model has higher accuracy and smaller prediction errors in estimating the MALC. The proportion of data with a relative percentage error less than 10% in the prediction results of the AISI-DSM codes is 45.31%, whereas the XGB model achieves a proportion of 87.57%, and the results calculated from current codes tend to be more conservative, with a large deviation, which needs to be further considered.
To consider the highly nonlinear and complex buckling behaviour of various sections of cold-formed steel (CFS) built-up columns, experimental and finite element (FE) methods are commonly used for calculating their axial compressive capacity, although these methods are time-consuming and costly. This paper proposes machine learning (ML) methods to overcome the issues of traditional methods for predicting the maximum axial load capacity (MALC) of CFS built-up columns. A total of 3839 samples from more than 33 different types of sections were collected from 43 published papers, including 817 experimental data and 3,022 FE simulation data. A total of 15 characteristic parameters, such as the second moment of area, the radius of gyration, and the polar second moment of area, are considered when nine different ML models are trained. The robustness of these models was compared via the Monte Carlo simulation method, and the predicted results were compared with the calculated results from the current codes. The results show that the extreme gradient boosting (XGB) model has higher accuracy and smaller prediction errors in estimating the MALC. The proportion of data with a relative percentage error less than 10% in the prediction results of the AISI-DSM codes is 45.31%, whereas the XGB model achieves a proportion of 87.57%, and the results calculated from current codes tend to be more conservative, with a large deviation, which needs to be further considered.
期刊：
IEEE Transactions on Geoscience and Remote Sensing,2024年62:1-13 ISSN：0196-2892
通讯作者：
Gao, Shijuan;Zhu, Jianjun;Fu, HQ
作者机构：
[Gao, Shijuan; Fu, Haiqiang; Zhu, Jianjun; Li, Yi] Cent South Univ, Sch Geosci & Infophys, Changsha 410017, Peoples R China.;[Zhao, Rong] Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha 410018, Peoples R China.
通讯机构：
[Gao, SJ; Fu, HQ ; Zhu, JJ] C;Cent South Univ, Sch Geosci & Infophys, Changsha 410017, Peoples R China.
关键词：
Photonics;Forestry;Surfaces;Noise;Histograms;Background noise;Vegetation mapping;Densely forested areas;gradient-constrained morphological operation (GCMOO);Ice;Cloud;and Land Elevation Satellite-2 (ICESat-2);improved elevation frequency histogram statistics (imEFHS);subcanopy topography
摘要：
The Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) has been widely used to obtain high-precision subcanopy topography. However, due to the vegetation cover over densely forested areas, the ground photons are sparse, which makes it difficult to accurately estimate the subcanopy topography over densely forested areas. In this article, we proposed a novel method for retrieving subcanopy topography over densely forested areas from ICESat-2/ATL03 data. First, the proposed method used an improved elevation frequency histogram statistics (imEFHS) method to obtain candidate ground seed photons (GSPs). In densely forested areas, the obtained candidate GSPs are easily misclassified as canopy photons. Therefore, we performed a gradient-constrained morphological operation (GCMOO) to identify erroneous GSPs. Finally, an erroneous GSPs refinement approach was derived to correct erroneous GSPs over densely forested areas. In addition, the subcanopy topography can be presented by the refined GSPs with cubic spline interpolation. ICESat-2/ATL03 data acquired over densely forested areas was selected for testing the proposed method. The results in the given test sites show that the proposed method can extract subcanopy topography accurately, with a root-mean-square error of 1.71 m over densely forested areas. We also compared the retrieved subcanopy topography results with National Aeronautics and Space Administration (NASA) ATL08 terrain samples. We found that the ratio of useful subcanopy topography results (residual <2.5 m) in the forest-intensive area was 87%. However, the ratio of useful ATL08 terrain samples was only 9%, which is lower than that of retrieved subcanopy topography results. In addition, in densely forested areas, the correlation ( $R^{2}$ ) between the retrieved subcanopy topography results and the reference high-precision digital terrain model (DTMs) reached 0.93, which is much higher than that of the ATL08 terrain samples ( $R^{2} =0.63$ ).
作者机构：
[Wang, Da; Zhang, Zhi; Li, Nanchuan] Changsha Univ Sci & Technol, Sch Civil Engn, Changsha 410114, Peoples R China.;[Wang, Da; Shi, Jialin] Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha 410004, Peoples R China.;[Tan, Benkun; Tan, BK] Hunan Univ Arts & Sci, Sch Civil & Architectural Engn, Changde 415000, Peoples R China.
通讯机构：
[Li, NC ] C;[Tan, BK ] H;Changsha Univ Sci & Technol, Sch Civil Engn, Changsha 410114, Peoples R China.;Hunan Univ Arts & Sci, Sch Civil & Architectural Engn, Changde 415000, Peoples R China.
关键词：
steel-concrete composite structures;fatigue testing;finite element analysis;critical plane method;Smith-Watson-Topper
摘要：
The fatigue performance of steel-concrete composite beams is crucial for ensuring structural safety. To account for the member's multiaxial stress state, this study employed the critical surface method, using fatigue damage parameters as an evaluation index for assessing fatigue performance. Static and fatigue performance tests on steel-concrete beams were conducted to identify failure characteristics, which informed the development of a finite element model that incorporates concrete damage. Using the SWT model, the most unfavorable loading parameters were determined by analyzing critical paths on the test beams, providing a basis for predicting how initial defects impact fatigue performance. The impact of initial defects on the fatigue performance of the composite beam is assessed using this criterion. The results indicate that the discrepancy between the actual and predicted load capacities of the test beam is within 5%, and cyclic loading significantly affects the test beam's mechanical properties, resulting in a 27% reduction in load capacity and a 48% increase in deflection after 2 million cycles. Finite element modeling reveals that components experience multiaxial stress, with test beam mechanical property changes aligning with predicted fatigue damage parameters, confirming the reliability of using these parameters as a criterion. As the strength of the composite beams diminished due to pore defects, the fatigue damage parameter escalated, increasing the likelihood of crack formation. However, once the concrete's strength fell to a level where the pegs were insufficiently constrained, the structural damage pattern shifted, and the fatigue damage parameter subsequently decreased.
