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2024 Vol. 54, No. 4
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2024, 54(4): 1-9.
doi: 10.3724/j.gyjzG22092810
Abstract:
The transformation of space production in the consumption era from material needs to differentiated and individualized needs has promoted the rise of spectacle culture and the arrival of the spectacle era. To discuss the relations among the spectacle culture, landscape society and consumerism, as well as the characteristics and causes of the spectacle era, the evolutional context of the main wonderful buildings since the 1960s was sorted out. It was found that consumerism had a decisive influence on the changes in the architectural language. In the absence of criticism, the architectural language could only passively adapt the changes in consumer cultures and gradually fall into the muddy of Spectacle Culture. By strengthening the polarized architectural language of formal autonomy, the prevailing new geometry could meet the needs for unrestricted manufacturing wonders, but it also deviated from the essence of architecture, which made architecture become a form game and a dependency of spectacle culture. It was pointed that to get rid of the predicament, the essence of architecture must return, and the architecture must be returned to the architectural logic and the spirit of places.
The transformation of space production in the consumption era from material needs to differentiated and individualized needs has promoted the rise of spectacle culture and the arrival of the spectacle era. To discuss the relations among the spectacle culture, landscape society and consumerism, as well as the characteristics and causes of the spectacle era, the evolutional context of the main wonderful buildings since the 1960s was sorted out. It was found that consumerism had a decisive influence on the changes in the architectural language. In the absence of criticism, the architectural language could only passively adapt the changes in consumer cultures and gradually fall into the muddy of Spectacle Culture. By strengthening the polarized architectural language of formal autonomy, the prevailing new geometry could meet the needs for unrestricted manufacturing wonders, but it also deviated from the essence of architecture, which made architecture become a form game and a dependency of spectacle culture. It was pointed that to get rid of the predicament, the essence of architecture must return, and the architecture must be returned to the architectural logic and the spirit of places.
2024, 54(4): 10-19.
doi: 10.3724/j.gyjzG22052807
Abstract:
Taking 1 255 traditional villages in the Yangtze River Delta as the research object, using GIS to analyze the spatial distribution and differentiation of traditional villages, and adopting the quantitative method of geo-detecting factors to analyze the relevant influencing factors. The results showed that: 1) the spatial distribution of traditional villages in the Yangtze River Delta is agglomerated, forming two high-density areas of Huangshan City and Lishui City; 2) traditional villages in the Yangtze River Delta show a distribution characteristic of "dense center and sparse surroundings", with great regional differences; 3) different factors have different effects on the spatial distribution of traditional villages in the Yangtze River Delta, the influence of natural conditions factors is obviously stronger than other factors, the interaction between natural conditions is stronger than other factors, the interaction of various influencing factors jointly affects the spatial distribution of traditional villages in the Yangtze River Delta.
Taking 1 255 traditional villages in the Yangtze River Delta as the research object, using GIS to analyze the spatial distribution and differentiation of traditional villages, and adopting the quantitative method of geo-detecting factors to analyze the relevant influencing factors. The results showed that: 1) the spatial distribution of traditional villages in the Yangtze River Delta is agglomerated, forming two high-density areas of Huangshan City and Lishui City; 2) traditional villages in the Yangtze River Delta show a distribution characteristic of "dense center and sparse surroundings", with great regional differences; 3) different factors have different effects on the spatial distribution of traditional villages in the Yangtze River Delta, the influence of natural conditions factors is obviously stronger than other factors, the interaction between natural conditions is stronger than other factors, the interaction of various influencing factors jointly affects the spatial distribution of traditional villages in the Yangtze River Delta.
2024, 54(4): 20-29.
doi: 10.3724/j.gyjzG23082101
Abstract:
Heritage corridors are a new attempt to integrate the conservation and utilization of cultural heritage across regions, supporting the recognition of values and living continuity among cultural heritage on a larger spatial scale. The study explored new ways to protect the cultural heritage of Huizhou from the perspective of cultural ecology, with Huizhou cultural heritage units as the "source" of the heritage, the minimum resistance model, gravity model, and circuit theory were used to generate and grade potential corridors, and traditional villages were set up as corridor "stations", it was constructed as a multi-dimensional and multi-layered network system of "source-corridor-station". Based on this, the strategy of ecological protection and cultural symbiosis was proposed under the spatial pattern of "one axis, one belt, multiple nuclei and two wings". In order to promote the networked protection of cultural heritage in Huizhou, and to provide a reference for its overall tourism planning and the deep integration of culture and tourism development.
Heritage corridors are a new attempt to integrate the conservation and utilization of cultural heritage across regions, supporting the recognition of values and living continuity among cultural heritage on a larger spatial scale. The study explored new ways to protect the cultural heritage of Huizhou from the perspective of cultural ecology, with Huizhou cultural heritage units as the "source" of the heritage, the minimum resistance model, gravity model, and circuit theory were used to generate and grade potential corridors, and traditional villages were set up as corridor "stations", it was constructed as a multi-dimensional and multi-layered network system of "source-corridor-station". Based on this, the strategy of ecological protection and cultural symbiosis was proposed under the spatial pattern of "one axis, one belt, multiple nuclei and two wings". In order to promote the networked protection of cultural heritage in Huizhou, and to provide a reference for its overall tourism planning and the deep integration of culture and tourism development.
2024, 54(4): 30-38.
doi: 10.3724/j.gyjzG22112007
Abstract:
In order to study the relations between the urban development of Luoyang and the urban heat island, the surface temperatures of the urban area in the past two decades were taken as the research object. Landsat satellite remote sensing data was used as the data source, and the temperature inversion method was used to study the surface temperatures at four different periods. The analysis was conducted by using ArcGIS, ENVI 5.3, and Origin 2018 software. The spatial distribution and spatiotemporal variation characteristics of the heat island effect, as well as the relations between surface temperature and land use type, were obtained. The results indicated that from 2001 to 2019, the surface temperature of the old city center (Xigong District) increased by 15, and the surface ℃ temperature of the new city center (Luolong District) increased by 11 ℃. Among different land use classifications, ℃ the surface temperature of water bodies was the lowest, and with the increase of the heat island, the cold island effect of water bodies had slightly increased. The surface temperature of the Luo River was 26 in 2001, with a ℃ cold island intensity of 12, and in 2019, it was 34 ℃ with a cold island intensity of 14 ℃.
In order to study the relations between the urban development of Luoyang and the urban heat island, the surface temperatures of the urban area in the past two decades were taken as the research object. Landsat satellite remote sensing data was used as the data source, and the temperature inversion method was used to study the surface temperatures at four different periods. The analysis was conducted by using ArcGIS, ENVI 5.3, and Origin 2018 software. The spatial distribution and spatiotemporal variation characteristics of the heat island effect, as well as the relations between surface temperature and land use type, were obtained. The results indicated that from 2001 to 2019, the surface temperature of the old city center (Xigong District) increased by 15, and the surface ℃ temperature of the new city center (Luolong District) increased by 11 ℃. Among different land use classifications, ℃ the surface temperature of water bodies was the lowest, and with the increase of the heat island, the cold island effect of water bodies had slightly increased. The surface temperature of the Luo River was 26 in 2001, with a ℃ cold island intensity of 12, and in 2019, it was 34 ℃ with a cold island intensity of 14 ℃.
2024, 54(4): 39-45.
doi: 10.3724/j.gyjzG22102901
Abstract:
A precast column with intermediate connections and a cast-in-place column of the same size were designed and manufactured, and the quasi-static test of the two specimens was conducted. The experimental results showed that the ultimate failure mode of the precast column with intermediate connections was the plastic hinge zone failure at the bottom of the column and the steel failure at the joint connection. The hysteresis curve of the precast column with intermediate connections was full, and the energy dissipation performance was equivalent to that of the cast-in-place column. The initial stiffness of the precast column with intermediate connections was slightly lower than that of the cast-in-place column, and the final stiffness was basically consistent with the cast-in-place column. The ductility coefficient of the precast column with intermediate connections was 3.1, which was 89% of the cast-in-place column, and the ductility performance was weak. When the connection interface did not fail, the seismic performance of the precast column was equivalent to that of the cast-in-place column.
A precast column with intermediate connections and a cast-in-place column of the same size were designed and manufactured, and the quasi-static test of the two specimens was conducted. The experimental results showed that the ultimate failure mode of the precast column with intermediate connections was the plastic hinge zone failure at the bottom of the column and the steel failure at the joint connection. The hysteresis curve of the precast column with intermediate connections was full, and the energy dissipation performance was equivalent to that of the cast-in-place column. The initial stiffness of the precast column with intermediate connections was slightly lower than that of the cast-in-place column, and the final stiffness was basically consistent with the cast-in-place column. The ductility coefficient of the precast column with intermediate connections was 3.1, which was 89% of the cast-in-place column, and the ductility performance was weak. When the connection interface did not fail, the seismic performance of the precast column was equivalent to that of the cast-in-place column.
2024, 54(4): 46-53.
doi: 10.3724/j.gyjzG23061103
Abstract:
The vibration-reduction effect of the MTMD system depends on the optimization of both Tuned Mass Damper (TMD) parameters and its arrangement. For the vertical vibration control of horizontal structures including large floors and aerial corridors, an optimal design method of the MTMD vibration-reduction system, which consists of the following two steps, was proposed: 1) the optimal parameters of TMD were derived from the frequency domain solution for a damped single degree of freedom structure with TMD; 2) each target-mode was extracted according to the dominated participated-mode-mass, and the TMDs with optimal parameters were arranged where the greatest mode-displacement appeared. The results showed that the method was simple, practical, and had high calculation efficiency. For pedestrian load excitations with different frequencies, the ideal vertical vibration-reduction effect could be achieved when the mass of MTMD was only 0.5% to that of the main structure.
The vibration-reduction effect of the MTMD system depends on the optimization of both Tuned Mass Damper (TMD) parameters and its arrangement. For the vertical vibration control of horizontal structures including large floors and aerial corridors, an optimal design method of the MTMD vibration-reduction system, which consists of the following two steps, was proposed: 1) the optimal parameters of TMD were derived from the frequency domain solution for a damped single degree of freedom structure with TMD; 2) each target-mode was extracted according to the dominated participated-mode-mass, and the TMDs with optimal parameters were arranged where the greatest mode-displacement appeared. The results showed that the method was simple, practical, and had high calculation efficiency. For pedestrian load excitations with different frequencies, the ideal vertical vibration-reduction effect could be achieved when the mass of MTMD was only 0.5% to that of the main structure.
2024, 54(4): 54-63.
doi: 10.3724/j.gyjzG23030801
Abstract:
A friction-based energy dissipation device consisting of a central steel plate, a pair of clamping angles and a single circular hole friction plate was designed. The device was applied to the upper joint of a 4-point connection lifting structure between a precast concrete wall panel and a steel frame, A6061-T6 aluminium alloy plates were used as friction plate material. Four sets of specimens were selected for quasi-static loading test, and the bolt preloads of specimens were 17.5, 32.9, 52.8, 71.8 kN, respectively, the effects of bolt preload on the hysteresis performance, initial stiffness, critical sliding friction, stability and energy dissipation capacity of the friction energy dissipation device were investigated; the results showed that the bolt preload force had a decisive role in the mechanical properties of the friction energy dissipation device; after the test loading, the bolt hole of the friction plate of specimen L-B1 had a compression deformation of 20 mm to one side due to extrusion deformation; compared with specimen L-B1, the initial stiffness values of specimens L-B2~L-B4 varied within 10%, therefore, the friction energy dissipation device had stable mechanical propertied. Compared with specimen L-B1, with the increase of bolt preload, the average peak sliding friction of specimens L-B2 to L-B4 increased by 31%, 39% and 55%, the critical sliding friction increased by 32%, 40% and 52%, the inter-storey drift angle increased by 99%, 106% and 110%, and the energy dissipation capacity decreased by 25%, 29% and 39%.
A friction-based energy dissipation device consisting of a central steel plate, a pair of clamping angles and a single circular hole friction plate was designed. The device was applied to the upper joint of a 4-point connection lifting structure between a precast concrete wall panel and a steel frame, A6061-T6 aluminium alloy plates were used as friction plate material. Four sets of specimens were selected for quasi-static loading test, and the bolt preloads of specimens were 17.5, 32.9, 52.8, 71.8 kN, respectively, the effects of bolt preload on the hysteresis performance, initial stiffness, critical sliding friction, stability and energy dissipation capacity of the friction energy dissipation device were investigated; the results showed that the bolt preload force had a decisive role in the mechanical properties of the friction energy dissipation device; after the test loading, the bolt hole of the friction plate of specimen L-B1 had a compression deformation of 20 mm to one side due to extrusion deformation; compared with specimen L-B1, the initial stiffness values of specimens L-B2~L-B4 varied within 10%, therefore, the friction energy dissipation device had stable mechanical propertied. Compared with specimen L-B1, with the increase of bolt preload, the average peak sliding friction of specimens L-B2 to L-B4 increased by 31%, 39% and 55%, the critical sliding friction increased by 32%, 40% and 52%, the inter-storey drift angle increased by 99%, 106% and 110%, and the energy dissipation capacity decreased by 25%, 29% and 39%.
2024, 54(4): 64-71.
doi: 10.13204/j.gyjzG23050606
Abstract:
Based on reducing the energy consumption of buildings and achieving the purpose of energy conservation and emission reduction, a set of stainless steel connectors suitable for a new type of precast concrete sandwich insulation wall panels was developed, which can realize the integrated prefabrication of external stone decoration and wall insulation. The shear performance tests of two stainless steel connectors were systematically carried out, and the results showed that the shear failure mode of the stone connection interface was brittle failure, the stone was separated from the concrete and the connector, the end of the connector was bent, and the vertical arrangement of fish-type connectors had a greater impact on the shear resistance of the connection interface than the horizontal arrangement, and the average measured shear bearing capacity was 22.2% greater. The shear failure mode of plate connectors was concrete cracking, the connector and anchor steel rebars deformed. In the specimens arranged with two or four plate connectors, the test values of shear bearing capacity of a single connector was 29.75 kN and 26.35 kN, respectively. Through theoretical calculation and comparative analysis of test data, it was found that the shear resistance of the two types of connectors were good, and both had large safety reserves.
Based on reducing the energy consumption of buildings and achieving the purpose of energy conservation and emission reduction, a set of stainless steel connectors suitable for a new type of precast concrete sandwich insulation wall panels was developed, which can realize the integrated prefabrication of external stone decoration and wall insulation. The shear performance tests of two stainless steel connectors were systematically carried out, and the results showed that the shear failure mode of the stone connection interface was brittle failure, the stone was separated from the concrete and the connector, the end of the connector was bent, and the vertical arrangement of fish-type connectors had a greater impact on the shear resistance of the connection interface than the horizontal arrangement, and the average measured shear bearing capacity was 22.2% greater. The shear failure mode of plate connectors was concrete cracking, the connector and anchor steel rebars deformed. In the specimens arranged with two or four plate connectors, the test values of shear bearing capacity of a single connector was 29.75 kN and 26.35 kN, respectively. Through theoretical calculation and comparative analysis of test data, it was found that the shear resistance of the two types of connectors were good, and both had large safety reserves.
2024, 54(4): 72-80.
doi: 10.3724/j.gyjzG23051909
Abstract:
The segmented construction with wet joints is one of the most effective methods to solve the transportation and installation difficulties of large prefabricated concrete viaduct components. To study the shear performance of the joint surface at the wet joint, four groups of 12 specimens were designed for double shear tests, taking into account the effects of reinforcement, concrete strength grade, joint surface roughing process, and other factors. The mechanical bite force coefficient c of the joint interface roughing process in the extended shear friction theory formula was fitted by using the least squares method. The research results showed that the joint surface roughing process had a significant influence on the shear bearing capacity of the specimens. The bearing capacity of the specimens with exposed aggregate, plastering strip, and chiseling surface roughing treatment were approximately 92.7% to 94.1%, 82.7% to 86.7%, and 66.7% to 71.1% of that of the monolithic specimens, respectively. The connecting rebars of joint surface could significantly improve the ductility, shear bearing capacity, and crack resistance of the specimens, and the increase in bearing capacity was about 47.3% to 65.0%. When the specimens reached the ultimate state, the strain distribution of the connecting rebars of joint surface was uneven, and the average strain of all the rebars was about 50% of the yield strain. The calculated values of the shear bearing capacity of various country codes were much lower than the test values, indicating a high safety margin. The fitted parameters could provide a reference for engineering applications.
The segmented construction with wet joints is one of the most effective methods to solve the transportation and installation difficulties of large prefabricated concrete viaduct components. To study the shear performance of the joint surface at the wet joint, four groups of 12 specimens were designed for double shear tests, taking into account the effects of reinforcement, concrete strength grade, joint surface roughing process, and other factors. The mechanical bite force coefficient c of the joint interface roughing process in the extended shear friction theory formula was fitted by using the least squares method. The research results showed that the joint surface roughing process had a significant influence on the shear bearing capacity of the specimens. The bearing capacity of the specimens with exposed aggregate, plastering strip, and chiseling surface roughing treatment were approximately 92.7% to 94.1%, 82.7% to 86.7%, and 66.7% to 71.1% of that of the monolithic specimens, respectively. The connecting rebars of joint surface could significantly improve the ductility, shear bearing capacity, and crack resistance of the specimens, and the increase in bearing capacity was about 47.3% to 65.0%. When the specimens reached the ultimate state, the strain distribution of the connecting rebars of joint surface was uneven, and the average strain of all the rebars was about 50% of the yield strain. The calculated values of the shear bearing capacity of various country codes were much lower than the test values, indicating a high safety margin. The fitted parameters could provide a reference for engineering applications.
2024, 54(4): 81-89.
doi: 10.3724/j.gyjzG21110904
Abstract:
The compressive design bearing capacity formula (CDBCF) for Y-type cast steel joints under axial and small eccentric compression was derived, in addition, the CDBCF was verified by the experimental data of the full-scale experiment. The derivation process could be summarized as the following three steps: 1) the ultimate bearing capacity formula (UBCF) of the simplified model of the joint was derived. The original joint was simplified to a mechanical model whose format of the bearing capacity formula could refer to that of the welded hollow spherical joint. Adopting the format of bearing capacity formula, a regression analysis was conducted based on the results of finite element analysis, to derive the UBCF of the simplified model that was under axial compression, bending moment and eccentric compression; 2) the CDBCF of the numerical model of the joint was derived. According to the results of the importance analysis of the geometric parameters and the results of finite element analysis, and based on the UBCF of the simplified model, the CDBCF of the numerical model was derived for the numerical model that was under axial and small eccentric compression. By modifying the CDBCF of the numerical model in accordance with the requirements in Technical Specification for Application of Connections of Structural Steel Casting(CECS 235:2008), the final CDBCF for the Y-type cast steel joint was obtained; 3) the CDBCF of the joint was verified. The full-scale experimental results of the joint were adopted to verify the CDBCF, and a comparison of the derived formula and the formula in CECS 235:2008 was conducted.
The compressive design bearing capacity formula (CDBCF) for Y-type cast steel joints under axial and small eccentric compression was derived, in addition, the CDBCF was verified by the experimental data of the full-scale experiment. The derivation process could be summarized as the following three steps: 1) the ultimate bearing capacity formula (UBCF) of the simplified model of the joint was derived. The original joint was simplified to a mechanical model whose format of the bearing capacity formula could refer to that of the welded hollow spherical joint. Adopting the format of bearing capacity formula, a regression analysis was conducted based on the results of finite element analysis, to derive the UBCF of the simplified model that was under axial compression, bending moment and eccentric compression; 2) the CDBCF of the numerical model of the joint was derived. According to the results of the importance analysis of the geometric parameters and the results of finite element analysis, and based on the UBCF of the simplified model, the CDBCF of the numerical model was derived for the numerical model that was under axial and small eccentric compression. By modifying the CDBCF of the numerical model in accordance with the requirements in Technical Specification for Application of Connections of Structural Steel Casting(CECS 235:2008), the final CDBCF for the Y-type cast steel joint was obtained; 3) the CDBCF of the joint was verified. The full-scale experimental results of the joint were adopted to verify the CDBCF, and a comparison of the derived formula and the formula in CECS 235:2008 was conducted.
2024, 54(4): 90-98.
doi: 10.3724/j.gyjzG23102005
Abstract:
Long-span spatial structures as public buildings have attracted much attention. Once an accident occurs, it will bring bad public opinions and adverse social impacts. A translational long-span retractable structure was taken as the research object. Firstly, the important members in the structure were found out based on sensitivity analysis. Then, the dynamic response of the structure under the failure condition of important members was analyzed by ANSYS/LS-DYNA. Finally, the stress-strain, vibration and displacement responses of important members and key points were monitored healthily. The results showed that whether the retractable roof structure was fully-closed, semi-open, or fully-open, the important members were generally distributed near the main truss and the secondary truss. By studying the collapse of the structure under various failure conditions, it was found that no matter whether a single member failed or multiple members failed at the same time, the failure of the structure would not lead to the failure of new members. Through the monitoring of the construction process of the structure, it was found that the overall structure was within the elastic range during the construction process, and the monitoring results were consistent with the numerical simulation results, which were well verified.
Long-span spatial structures as public buildings have attracted much attention. Once an accident occurs, it will bring bad public opinions and adverse social impacts. A translational long-span retractable structure was taken as the research object. Firstly, the important members in the structure were found out based on sensitivity analysis. Then, the dynamic response of the structure under the failure condition of important members was analyzed by ANSYS/LS-DYNA. Finally, the stress-strain, vibration and displacement responses of important members and key points were monitored healthily. The results showed that whether the retractable roof structure was fully-closed, semi-open, or fully-open, the important members were generally distributed near the main truss and the secondary truss. By studying the collapse of the structure under various failure conditions, it was found that no matter whether a single member failed or multiple members failed at the same time, the failure of the structure would not lead to the failure of new members. Through the monitoring of the construction process of the structure, it was found that the overall structure was within the elastic range during the construction process, and the monitoring results were consistent with the numerical simulation results, which were well verified.
2024, 54(4): 99-107.
doi: 10.3724/j.gyjzG23112115
Abstract:
Taking the 800 kV wall bushing of a typical ultra-high voltage valve hall as the research object, seven finite element models were established considering different coupling modes between the 800 kV bushing and the steel structure valve hall, valve tower, 400 kV wall bushing, and firewall. The seismic response laws of the wall bushing and its end plates were studied. The research results showed that the stress amplitude of end plates of the 800 kV wall bushing increaseed by 21.7% to 26.6%, while the lateral acceleration amplitude increased by 20.5% to 31.1%, after considering the coupling effect with the steel structure valve hall, firewall, and 400 kV wall bushing. The stress amplitude of the outer casing pipe was relatively larger, approximately 1.06-1.17 times that of the inner casing pipe. The coupling effect between the valve hall structure and the equipment had increased the stress amplitude of the inner casing pipe by 10.3-11.9%, while there was no significant impact on the stress of the outer casing pipe (with a maximum difference of only 0.62%). The coupling effect of structural equipment significantly increased the relative displacement between the conductive rod and the inner wall of the casing pipe, increasing the lateral relative displacement by 20.6-63.4% and the longitudinal relative displacement by 38.5-42.8%. Therefore, in the design, selection, and strength verification of wall bushings, the adverse effects of the coupling effect between the steel structure valve hall and the equipment should be comprehensively considered in order to obtain more scientific and accurate conclusions.
Taking the 800 kV wall bushing of a typical ultra-high voltage valve hall as the research object, seven finite element models were established considering different coupling modes between the 800 kV bushing and the steel structure valve hall, valve tower, 400 kV wall bushing, and firewall. The seismic response laws of the wall bushing and its end plates were studied. The research results showed that the stress amplitude of end plates of the 800 kV wall bushing increaseed by 21.7% to 26.6%, while the lateral acceleration amplitude increased by 20.5% to 31.1%, after considering the coupling effect with the steel structure valve hall, firewall, and 400 kV wall bushing. The stress amplitude of the outer casing pipe was relatively larger, approximately 1.06-1.17 times that of the inner casing pipe. The coupling effect between the valve hall structure and the equipment had increased the stress amplitude of the inner casing pipe by 10.3-11.9%, while there was no significant impact on the stress of the outer casing pipe (with a maximum difference of only 0.62%). The coupling effect of structural equipment significantly increased the relative displacement between the conductive rod and the inner wall of the casing pipe, increasing the lateral relative displacement by 20.6-63.4% and the longitudinal relative displacement by 38.5-42.8%. Therefore, in the design, selection, and strength verification of wall bushings, the adverse effects of the coupling effect between the steel structure valve hall and the equipment should be comprehensively considered in order to obtain more scientific and accurate conclusions.
2024, 54(4): 108-116.
doi: 10.13204/j.gyjzG22081307
Abstract:
In order to investigate and analyze the impact resistance of steel-concrete composite panels, ABAQUS software was used to establish the finite element (FE) models of single-layer steel-concrete composite (HSC) panels and double-skin steel-concrete composite (SCS) panels. The reliability of the finite element modeling was validated against the results of drop-hammer impact test. Firstly, the whole impact process of this type of members was analyzed. Secondly, the impact resistance of HSC panels was compared with that of SCS panels from three aspects of dynamic response, failure mode and energy absorption coefficient. Finally, the influence of the steel plate ratio and impact height on the dynamic responses of members were emphatically discussed and the impact force time-history curve was simplified. The results showed that the FE model could reasonably predict the impact force and deflection of steel-concrete composite panels. The whole impact process of this type of members could be divided as four stages. The impact resistance of SCS panels was superior to HSC panels. The simplified impact-force history suggested in this work could be effectively employed in the impact resistance design of this kind of members.
In order to investigate and analyze the impact resistance of steel-concrete composite panels, ABAQUS software was used to establish the finite element (FE) models of single-layer steel-concrete composite (HSC) panels and double-skin steel-concrete composite (SCS) panels. The reliability of the finite element modeling was validated against the results of drop-hammer impact test. Firstly, the whole impact process of this type of members was analyzed. Secondly, the impact resistance of HSC panels was compared with that of SCS panels from three aspects of dynamic response, failure mode and energy absorption coefficient. Finally, the influence of the steel plate ratio and impact height on the dynamic responses of members were emphatically discussed and the impact force time-history curve was simplified. The results showed that the FE model could reasonably predict the impact force and deflection of steel-concrete composite panels. The whole impact process of this type of members could be divided as four stages. The impact resistance of SCS panels was superior to HSC panels. The simplified impact-force history suggested in this work could be effectively employed in the impact resistance design of this kind of members.
2024, 54(4): 117-125.
doi: 10.3724/j.gyjzG22052005
Abstract:
The design and analysis of the suspension reticulated shell using green renewable wood plastic as the main material were carried out. Through tests and analysis, the related properties of various materials were compared, and the wood-plastic co-extrusion material was innovatively used as the main force rod of the reticulated shell. According to the requirements of building and wiring, the section form of wood-plastic rod was designed, and a new steel-wood-plastic combined joint was developed. The finite element analysis software was used to carry out mechanical analysis of the reticulated shell model, and the internal force, displacement and deflection of the structure with different joints were compared. Eigenvalue buckling analysis and geometric nonlinear buckling analysis considering initial defects were carried out for the reticulated shell, and the safety factor of the reticulated shell was obtained. The analysis results showed that the internal force, deformation and stability of the new reticulated shell in normal use could meet the requirements of the current relevant specifications, and it has the value of popularization and application.
The design and analysis of the suspension reticulated shell using green renewable wood plastic as the main material were carried out. Through tests and analysis, the related properties of various materials were compared, and the wood-plastic co-extrusion material was innovatively used as the main force rod of the reticulated shell. According to the requirements of building and wiring, the section form of wood-plastic rod was designed, and a new steel-wood-plastic combined joint was developed. The finite element analysis software was used to carry out mechanical analysis of the reticulated shell model, and the internal force, displacement and deflection of the structure with different joints were compared. Eigenvalue buckling analysis and geometric nonlinear buckling analysis considering initial defects were carried out for the reticulated shell, and the safety factor of the reticulated shell was obtained. The analysis results showed that the internal force, deformation and stability of the new reticulated shell in normal use could meet the requirements of the current relevant specifications, and it has the value of popularization and application.
2024, 54(4): 126-133.
doi: 10.13204/j.gyjzG22110102
Abstract:
The three-dimensional nonlinear finite element analysis of the bending properties of prestressed steel-bamboo composite I-beams was carried out by using the finite element software ABAQUS, the anisotropy and yield criterion of recombinant bamboo were considered in the model, the cohesion element was introduced to simulate the bonding slip of the steel-bamboo interface, and the simulation results were compared with the test results, and the influence of prestress on the bending properties of the composite beam was discussed. The results showed that the failure characteristics, the load-deflection curves, the allowable load and the maximum mid-span deflection of the prestressed steel-bamboo composite beams in the test and simulation were consistent. The configuration of prestressed ribs could improve the stiffness of the composite beam, but with the increase of the prestress value, the stiffness of the composite beam did not change significantly, the ultimate bearing capacity and deformability were improved, and the failure of the glue layer at the steel-bamboo interface was delayed. When the prestress was too large, it would lead to premature degumming of the steel-bamboo interface of the composite beam and the reduction in the ultimate bearing capacity. In order to meet the requirements of bearing capacity and deformation performance, it was recommended that the prestress application value should be the allowable bearing capacity value of ordinary steel-bamboo composite I-beams.
The three-dimensional nonlinear finite element analysis of the bending properties of prestressed steel-bamboo composite I-beams was carried out by using the finite element software ABAQUS, the anisotropy and yield criterion of recombinant bamboo were considered in the model, the cohesion element was introduced to simulate the bonding slip of the steel-bamboo interface, and the simulation results were compared with the test results, and the influence of prestress on the bending properties of the composite beam was discussed. The results showed that the failure characteristics, the load-deflection curves, the allowable load and the maximum mid-span deflection of the prestressed steel-bamboo composite beams in the test and simulation were consistent. The configuration of prestressed ribs could improve the stiffness of the composite beam, but with the increase of the prestress value, the stiffness of the composite beam did not change significantly, the ultimate bearing capacity and deformability were improved, and the failure of the glue layer at the steel-bamboo interface was delayed. When the prestress was too large, it would lead to premature degumming of the steel-bamboo interface of the composite beam and the reduction in the ultimate bearing capacity. In order to meet the requirements of bearing capacity and deformation performance, it was recommended that the prestress application value should be the allowable bearing capacity value of ordinary steel-bamboo composite I-beams.
2024, 54(4): 134-141.
doi: 10.3724/j.gyjzG23080713
Abstract:
The periodic excitation of wind turbines under operating conditions will generate harmonic disturbances with similar frequencies to the structural modes, which will affect the vibration level of the fundamental modes of the structure and the identification of the dynamic parameters. In order to effectively and continuously monitor the tower vibration status during operation, the covariance-driven stochastic subspace identification (Cov-SSI) method based on potential hierarchical agglomerative clustering (PHA) combined with the probability density function (PDF) was proposed for the automatic identification of modal parameters of wind turbine towers. Through the on-site vibration response test, the Cov-SSI method was firstly used to initially identify the tower structure modal parameters; secondly, the PHA method was introduced to improve the stability diagram, and the frequency and modal confidence criterion (MAC) distance matrix was defined for cleaning and clustering to automate the separation of different orders of modes; finally, the information of the clustered clusters was used to determine and eliminate the harmonic modes by the PDF method. The results showed that the proposed method could effectively separate and eliminate the harmonic components, realize the automatic identification of the modal parameters of wind turbine towers under operation, and provide a good engineering application value for the automated real-time monitoring of wind turbine safety operation.
The periodic excitation of wind turbines under operating conditions will generate harmonic disturbances with similar frequencies to the structural modes, which will affect the vibration level of the fundamental modes of the structure and the identification of the dynamic parameters. In order to effectively and continuously monitor the tower vibration status during operation, the covariance-driven stochastic subspace identification (Cov-SSI) method based on potential hierarchical agglomerative clustering (PHA) combined with the probability density function (PDF) was proposed for the automatic identification of modal parameters of wind turbine towers. Through the on-site vibration response test, the Cov-SSI method was firstly used to initially identify the tower structure modal parameters; secondly, the PHA method was introduced to improve the stability diagram, and the frequency and modal confidence criterion (MAC) distance matrix was defined for cleaning and clustering to automate the separation of different orders of modes; finally, the information of the clustered clusters was used to determine and eliminate the harmonic modes by the PDF method. The results showed that the proposed method could effectively separate and eliminate the harmonic components, realize the automatic identification of the modal parameters of wind turbine towers under operation, and provide a good engineering application value for the automated real-time monitoring of wind turbine safety operation.
2024, 54(4): 142-148.
doi: 10.3724/j.gyjzG22091601
Abstract:
Landslide and retaining wall collapse damage will cause rapid sliding between geogrids and soil, and the interaction of reinforced soil interfaces is complicated. It helps to deepen the understanding for mechanical characteristics of reinforced soil interfaces by studying the force and deformation characteristics of reinforced materials at interfaces at different pollout rates. Thus, the pullout tests with nine pullout rates and 3 normal loads were conducted, which were expected to explore the effect laws of pullout rates and normal loads on mechanical characteristics of reinforced soil interfaces. The results showed that the increase degrees of peak pullout force gradually slowed down with the increase in pullout rates. The interfacial cohesion was positively correlated with pullout rates, and it had grown by a maximum of 278%; the interfacial friction angle was negative correlated with pullout rates, and it had decreased by a maximun of 19.1%. The strain of the geogrids was more seriously influenced by pullout rates at low speeds and increased with the increase in pullout rates; when the pullout rate exceeded 5 mm/min, the strain variance of geogrids decreased and the pullout stiffness of geogrids increased. The interfacial shear dilation increased with the increase in pullout rates, and decreased with the increase in normal loads. The interfacial shear dilation at high speed was about 1.56 times of that at low speed and about 1.13 times of that at medium speed.
Landslide and retaining wall collapse damage will cause rapid sliding between geogrids and soil, and the interaction of reinforced soil interfaces is complicated. It helps to deepen the understanding for mechanical characteristics of reinforced soil interfaces by studying the force and deformation characteristics of reinforced materials at interfaces at different pollout rates. Thus, the pullout tests with nine pullout rates and 3 normal loads were conducted, which were expected to explore the effect laws of pullout rates and normal loads on mechanical characteristics of reinforced soil interfaces. The results showed that the increase degrees of peak pullout force gradually slowed down with the increase in pullout rates. The interfacial cohesion was positively correlated with pullout rates, and it had grown by a maximum of 278%; the interfacial friction angle was negative correlated with pullout rates, and it had decreased by a maximun of 19.1%. The strain of the geogrids was more seriously influenced by pullout rates at low speeds and increased with the increase in pullout rates; when the pullout rate exceeded 5 mm/min, the strain variance of geogrids decreased and the pullout stiffness of geogrids increased. The interfacial shear dilation increased with the increase in pullout rates, and decreased with the increase in normal loads. The interfacial shear dilation at high speed was about 1.56 times of that at low speed and about 1.13 times of that at medium speed.
2024, 54(4): 149-157.
doi: 10.3724/j.gyjzG23080702
Abstract:
To more accurately reflect the test results of the bearing capacity of piles by self-balanced tests in soft rock foundation, an analytical transformation algorithm for the tested bearing capacity of rock-socketed piles by selfbalanced tests was proposed. Firstly, the shear mechanism of interfaces between piles and soft rock was analyzed, and a transfer function of loads and model for the interfaces between piles and soft rock were established considering the three shear stages of cementation, shear dilation and slip. Secondly, the analytical solution for loading-settlement curves of piles by the self-balanced tests was deduced considering the influence of the pile weight of the upper section on the loading box and combining the load transfer function of the interface between piles and rock. Comparing the measured data of two test piles with the calculating results by the analytical solution, the accuracy calculating results by the analytical solutions was 87.3% and 85.6% respectively. Eventually, based on the existing simplified transformation method, an analytical transformation method was proposed. Comparing the results with the precise transformation solutions, the accuracy of the calculating results by the analytical transformation solution was respectively improved by 15.3% and 17.4% compared with the calculating results by the simplified transformation method. The analytical transformation method was simple, practical, and more accurate, which could provide reference to self-balancing tests in engineering with rock-socketed piles in soft rock.
To more accurately reflect the test results of the bearing capacity of piles by self-balanced tests in soft rock foundation, an analytical transformation algorithm for the tested bearing capacity of rock-socketed piles by selfbalanced tests was proposed. Firstly, the shear mechanism of interfaces between piles and soft rock was analyzed, and a transfer function of loads and model for the interfaces between piles and soft rock were established considering the three shear stages of cementation, shear dilation and slip. Secondly, the analytical solution for loading-settlement curves of piles by the self-balanced tests was deduced considering the influence of the pile weight of the upper section on the loading box and combining the load transfer function of the interface between piles and rock. Comparing the measured data of two test piles with the calculating results by the analytical solution, the accuracy calculating results by the analytical solutions was 87.3% and 85.6% respectively. Eventually, based on the existing simplified transformation method, an analytical transformation method was proposed. Comparing the results with the precise transformation solutions, the accuracy of the calculating results by the analytical transformation solution was respectively improved by 15.3% and 17.4% compared with the calculating results by the simplified transformation method. The analytical transformation method was simple, practical, and more accurate, which could provide reference to self-balancing tests in engineering with rock-socketed piles in soft rock.
2024, 54(4): 158-165.
doi: 10.3724/j.gyjzG23073101
Abstract:
Based on on-site measured long-term soil settlement data, the Peck empirical formula was used to study the shape, width coefficient and influence range of transversal settlement troughs of ground and deep strata. The results showed that: 1) The long-term settlement of strata caused by shield tunneling, whether it was transversal settlement of ground or deep stratum settlement, conformed to the Gaussian distribution. Affected by the consolidation of disturbed soil, the settlement trough gradually deepened and widened. 2) From the perspective of ground settlement, the transversal settlement caused by shield tunneling construction was in a range of 1.4 times tunnel diameters, which would increase to a range of 2.3 times tunnel diameters due to long-term consolidation of soil. For the deep stratum settlement (buried at a depth of 12.1 m), the affected range by shield tunneling was 0.8 times of tunnel diameters, and over time, the affected range would expand to a range of 1.2 times tunnel diameters. The affected range by shield tunneling in the deep stratum was smaller than that in the ground. 3) The settlement width coefficients of the ground and deep stratum conformed to an exponential distribution with the time of disengagement of the shield tail from the measured cross-section, and leveled off eventually. However, the growth rate and amount of the width coefficient of ground settlement troughs were greater than those of deep soil. 4) The transveral settlement curve the of deep stratum was steep, while the transversal settlement curve of the ground was relatively flat. The curvature of the transversal settlement curve of the deep stratum was larger and more concentrated than that of the ground.
Based on on-site measured long-term soil settlement data, the Peck empirical formula was used to study the shape, width coefficient and influence range of transversal settlement troughs of ground and deep strata. The results showed that: 1) The long-term settlement of strata caused by shield tunneling, whether it was transversal settlement of ground or deep stratum settlement, conformed to the Gaussian distribution. Affected by the consolidation of disturbed soil, the settlement trough gradually deepened and widened. 2) From the perspective of ground settlement, the transversal settlement caused by shield tunneling construction was in a range of 1.4 times tunnel diameters, which would increase to a range of 2.3 times tunnel diameters due to long-term consolidation of soil. For the deep stratum settlement (buried at a depth of 12.1 m), the affected range by shield tunneling was 0.8 times of tunnel diameters, and over time, the affected range would expand to a range of 1.2 times tunnel diameters. The affected range by shield tunneling in the deep stratum was smaller than that in the ground. 3) The settlement width coefficients of the ground and deep stratum conformed to an exponential distribution with the time of disengagement of the shield tail from the measured cross-section, and leveled off eventually. However, the growth rate and amount of the width coefficient of ground settlement troughs were greater than those of deep soil. 4) The transveral settlement curve the of deep stratum was steep, while the transversal settlement curve of the ground was relatively flat. The curvature of the transversal settlement curve of the deep stratum was larger and more concentrated than that of the ground.
2024, 54(4): 166-172.
doi: 10.3724/j.gyjzG22090705
Abstract:
The residual settlement in goafs has a great influence on the stability of expressways. To analyze the influence of residual settlement in goafs under expressways on the stability of high and steep slopes, several test schemes were designed and stabillty analysis of high and steep slopes was performed. By the optimization study for the stability of deeply excavated slopes, it was concluded that the slope angle was the main factor affecting the stability of slopes, followed by the slope height, the internal friction angle and cohesion of rock masses, and the gravity densities of rock masses. The relational formulas between cohesion and slope safety factors, internal friction angle and slope safety factors were obtained, and the safety factor formula of slopes in simultaneous reduction of cohesion and internal friction angle was also obtained. The result showed that the residual settlement in goafs seriously affected the stability of deeply excavated slopes. The equivalent simulations of residual settlement could provide reference to influence evaluation of residual settlement on stability of deeply excavated slopes in goafs.
The residual settlement in goafs has a great influence on the stability of expressways. To analyze the influence of residual settlement in goafs under expressways on the stability of high and steep slopes, several test schemes were designed and stabillty analysis of high and steep slopes was performed. By the optimization study for the stability of deeply excavated slopes, it was concluded that the slope angle was the main factor affecting the stability of slopes, followed by the slope height, the internal friction angle and cohesion of rock masses, and the gravity densities of rock masses. The relational formulas between cohesion and slope safety factors, internal friction angle and slope safety factors were obtained, and the safety factor formula of slopes in simultaneous reduction of cohesion and internal friction angle was also obtained. The result showed that the residual settlement in goafs seriously affected the stability of deeply excavated slopes. The equivalent simulations of residual settlement could provide reference to influence evaluation of residual settlement on stability of deeply excavated slopes in goafs.
2024, 54(4): 173-179.
doi: 10.3724/j.gyjzG23081502
Abstract:
In engineering construction, layered rock slopes are very common. Affected by their structural planes, the instability and deformation characteristics of those slopes are more complicated, therefore, it has caused certain difficulties in the design of support engineering. Thus, numerical models with different dip angles of strata were constructed based on a high and steep rock bedding slope as the prototype by the software PFC2D. A method of searching for potential sliding surfaces of slopes by the inversion method of critical loads was proposed and mesoscopic analysis on the process of deformation, instabibity and failure was performed. By comparing critical load coefficients, the relative stability of slopes with different dip angles of strata was obtained. The support effect of wall-anchor systems with different dip angles of strata was obviously different. The support effect of horizontal rock slopes and cut bedding slopes with large dig angles were better, while the supporting effect of reverse slopes were worse. In the optimization of support design for slopes, to increase the embedment ratio and embement angle within a certain range could improve the support effect. From the perspective of construction and economy, the support design with an embedment ratio of 0.33 and an embedment angle of 90° was recommended.
In engineering construction, layered rock slopes are very common. Affected by their structural planes, the instability and deformation characteristics of those slopes are more complicated, therefore, it has caused certain difficulties in the design of support engineering. Thus, numerical models with different dip angles of strata were constructed based on a high and steep rock bedding slope as the prototype by the software PFC2D. A method of searching for potential sliding surfaces of slopes by the inversion method of critical loads was proposed and mesoscopic analysis on the process of deformation, instabibity and failure was performed. By comparing critical load coefficients, the relative stability of slopes with different dip angles of strata was obtained. The support effect of wall-anchor systems with different dip angles of strata was obviously different. The support effect of horizontal rock slopes and cut bedding slopes with large dig angles were better, while the supporting effect of reverse slopes were worse. In the optimization of support design for slopes, to increase the embedment ratio and embement angle within a certain range could improve the support effect. From the perspective of construction and economy, the support design with an embedment ratio of 0.33 and an embedment angle of 90° was recommended.
2024, 54(4): 180-187.
doi: 10.3724/j.gyjzG23071204
Abstract:
Through experiments of the prestressed concrete with strength grades of C40, C50, C60 and C70 experiencing given ultralow temperatures, the changing regularities of precompression deformation performances of the prestressed concrete were investigated and the corresponding influence difference of two typical low temperature environments with –80 and ℃ –160 on them ℃ was examined. The results showed that the precompression strain differential rates at the cooling target points and the temperature uniformity target points increased evenly with the increase in the concrete strength grade under low temperature condition, but there were apparent differences for the influence of different low temperatures on them; for different low temperature conditions, the transient precompression strain changing rates and the precompression strain relative changing rates of prestressed concrete at the cooling stages generally increased with the increase in the concrete strength grades except for the strength grade of C40, but varied complexly at the constant temperature stages; while the precompression strains of the prestressed concrete with different strength grades still increased at the constant temperature stages under low temperatures, but likewise there were apparent differences for the influence of different low temperatures on them. The experimental results and corresponding fitting formulas can provide valuable references for the design and safety assessment of prestressed concrete structures as LNG storage tanks.
Through experiments of the prestressed concrete with strength grades of C40, C50, C60 and C70 experiencing given ultralow temperatures, the changing regularities of precompression deformation performances of the prestressed concrete were investigated and the corresponding influence difference of two typical low temperature environments with –80 and ℃ –160 on them ℃ was examined. The results showed that the precompression strain differential rates at the cooling target points and the temperature uniformity target points increased evenly with the increase in the concrete strength grade under low temperature condition, but there were apparent differences for the influence of different low temperatures on them; for different low temperature conditions, the transient precompression strain changing rates and the precompression strain relative changing rates of prestressed concrete at the cooling stages generally increased with the increase in the concrete strength grades except for the strength grade of C40, but varied complexly at the constant temperature stages; while the precompression strains of the prestressed concrete with different strength grades still increased at the constant temperature stages under low temperatures, but likewise there were apparent differences for the influence of different low temperatures on them. The experimental results and corresponding fitting formulas can provide valuable references for the design and safety assessment of prestressed concrete structures as LNG storage tanks.
2024, 54(4): 188-194.
doi: 10.3724/j.gyjzG23040610
Abstract:
In order to study the mechanical properties of high-ductility ECC materials instead of conventional expansion devices in continuous bridge deck structures, the depth of the post-cast groove and the presence or absence of bonding of rebars were used as variable parameters, designed and fabricated four sets of high-ductility ECC bridge deck joint plate scaled model members, conducted tests on the mechanical properties of joint plates under combined bending and tension conditions. The results showed that the top surface of the ECC joint plate showed the phenomenon of multi-point cracking with fine cracks, the crack width was within 0.2 mm, the ECC material itself exerted a better crack resistance; increasing the depth of the post-cast groove could improve the mechanical properties of the joint plate, but it weakened the ductility of the joint plate, the unbonded section of the rebars could significantly release the restraining effect of the rebars on the ECC matrix, and then better utilize the high ductility of the ECC joint plate.
In order to study the mechanical properties of high-ductility ECC materials instead of conventional expansion devices in continuous bridge deck structures, the depth of the post-cast groove and the presence or absence of bonding of rebars were used as variable parameters, designed and fabricated four sets of high-ductility ECC bridge deck joint plate scaled model members, conducted tests on the mechanical properties of joint plates under combined bending and tension conditions. The results showed that the top surface of the ECC joint plate showed the phenomenon of multi-point cracking with fine cracks, the crack width was within 0.2 mm, the ECC material itself exerted a better crack resistance; increasing the depth of the post-cast groove could improve the mechanical properties of the joint plate, but it weakened the ductility of the joint plate, the unbonded section of the rebars could significantly release the restraining effect of the rebars on the ECC matrix, and then better utilize the high ductility of the ECC joint plate.
2024, 54(4): 195-199.
doi: 10.3724/j.gyjzG23121118
Abstract:
With the wide application of low-heat Portland cement in hydraulic projects, higher requirements are put forward for the mechanical properties of low-heat Portland cement concrete. In this study, the underwater steel ball method was used to quantify the influence of silica fume content (0, 3% and 5%) on the basic mechanical properties and other mechanical properties of low-heat Portland cement concrete. The results showed that the addition of silica fume could effectively improve the abrasion resistance of low-heat Portland cement concrete, which increased by 12.2% when the content was 3%, and increased by 14.6% when the content was 5%. Compared to concrete without adding silicon powder, when 3% silica fume was added, the compressive strength and split tensile strength of low-heat Portland concrete were respectively reduced by about 3.5%-6.0%, 3.8%-11.1%; axial tensile properties (axial tensile strength and ultimate tensile value) increased by about 7.0%; when 5% silica fume was added, the compressive strength, splitting tensile strength and axial tensile properties could be respectively increased by about 3.6%-7.0%, 2.8%-3.5%, 6.9%-14.8%. Therefore, a relatively ideal overall performance could be obtained when the content of silica fume was 5%.
With the wide application of low-heat Portland cement in hydraulic projects, higher requirements are put forward for the mechanical properties of low-heat Portland cement concrete. In this study, the underwater steel ball method was used to quantify the influence of silica fume content (0, 3% and 5%) on the basic mechanical properties and other mechanical properties of low-heat Portland cement concrete. The results showed that the addition of silica fume could effectively improve the abrasion resistance of low-heat Portland cement concrete, which increased by 12.2% when the content was 3%, and increased by 14.6% when the content was 5%. Compared to concrete without adding silicon powder, when 3% silica fume was added, the compressive strength and split tensile strength of low-heat Portland concrete were respectively reduced by about 3.5%-6.0%, 3.8%-11.1%; axial tensile properties (axial tensile strength and ultimate tensile value) increased by about 7.0%; when 5% silica fume was added, the compressive strength, splitting tensile strength and axial tensile properties could be respectively increased by about 3.6%-7.0%, 2.8%-3.5%, 6.9%-14.8%. Therefore, a relatively ideal overall performance could be obtained when the content of silica fume was 5%.
2024, 54(4): 200-206.
doi: 10.3724/j.gyjzG23090504
Abstract:
In order to study the mechanical response characteristics of GFRP reinforced sea sand concrete pavement under vehicle loads, GFRP reinforced sea sand concrete pavement is applied to engineering practice. In this study, a 17 m×98 m GFRP reinforced sea sand concrete pavement was poured in the field vehicle test, and the field test showed that the change of rebar type and single-layer reinforcement ratio had little effect on the strain of the road panel under vehicle loads. At the same time, based on the field test data, the finite element model of the GFRP reinforced sea sand concrete pavement was established for parameter sensitivity analysis, and the results showed that the calculation results of the finite element model were close to the experimental data, and the model had high reliability, and the changes of the elastic modulus of GFRP panel rebars, the spacing of GFRP longitudinal rebars, the diameter of dowel bars and the elastic modulus of dowel bars had little effect on the maximum tensile stress of the GFRP reinforced sea sand concrete panel, and the load transfer performance of GFRP dowel bars was weaker than that of reforcing steel dowel bars. In actual engineering, the load transfer capacity of transverse joints can be improved by increasing the diameter of GFRP dowel bars.
In order to study the mechanical response characteristics of GFRP reinforced sea sand concrete pavement under vehicle loads, GFRP reinforced sea sand concrete pavement is applied to engineering practice. In this study, a 17 m×98 m GFRP reinforced sea sand concrete pavement was poured in the field vehicle test, and the field test showed that the change of rebar type and single-layer reinforcement ratio had little effect on the strain of the road panel under vehicle loads. At the same time, based on the field test data, the finite element model of the GFRP reinforced sea sand concrete pavement was established for parameter sensitivity analysis, and the results showed that the calculation results of the finite element model were close to the experimental data, and the model had high reliability, and the changes of the elastic modulus of GFRP panel rebars, the spacing of GFRP longitudinal rebars, the diameter of dowel bars and the elastic modulus of dowel bars had little effect on the maximum tensile stress of the GFRP reinforced sea sand concrete panel, and the load transfer performance of GFRP dowel bars was weaker than that of reforcing steel dowel bars. In actual engineering, the load transfer capacity of transverse joints can be improved by increasing the diameter of GFRP dowel bars.
2024, 54(4): 207-218.
doi: 10.13204/j.gyjzG23020707
Abstract:
Precast concrete cladding panel serves as a high performance non-structural envelope element. The connection system between the cladding panels and the main structure is a critical factor affecting the seismic performance of the structure. The connection methods between the cladding panels and the main structure can be classified into three categories: rigid connection, flexible connection, and energy-dissipative connection. Researchers have developed some new connections and studied their effects on the seismic performance of the main structure. The results demonstrated that when rigid connections were used between the panels and the main structure, significant interaction occurred, resulting in increased structural stiffness, strength, and seismic response. Proper flexible connections could facilitate relative independent deformation between the panels and the main structure, thereby reducing the impact of the panels on the main structure. Flexible connections were highly dependent on the construction manner, as well as the quality and precision of the construction. Energy-dissipative connections could utilize the relative deformation between the panels and the main structure to dissipate seismic energy, thereby proficiently controlling the damage to both the main structure and the panels. The paper provided a review and summary of the aforementioned research and offered prospects for further studies.
Precast concrete cladding panel serves as a high performance non-structural envelope element. The connection system between the cladding panels and the main structure is a critical factor affecting the seismic performance of the structure. The connection methods between the cladding panels and the main structure can be classified into three categories: rigid connection, flexible connection, and energy-dissipative connection. Researchers have developed some new connections and studied their effects on the seismic performance of the main structure. The results demonstrated that when rigid connections were used between the panels and the main structure, significant interaction occurred, resulting in increased structural stiffness, strength, and seismic response. Proper flexible connections could facilitate relative independent deformation between the panels and the main structure, thereby reducing the impact of the panels on the main structure. Flexible connections were highly dependent on the construction manner, as well as the quality and precision of the construction. Energy-dissipative connections could utilize the relative deformation between the panels and the main structure to dissipate seismic energy, thereby proficiently controlling the damage to both the main structure and the panels. The paper provided a review and summary of the aforementioned research and offered prospects for further studies.
2024, 54(4): 219-227.
doi: 10.13204/j.gyjzG23082306
Abstract:
Tensile tests were conducted on a new type of GFRP-steel composite bars, the failure process and mechanical performance indicators of the composite bars were analyzed. A theoretical model of stress-strain relations for the new type of GFRP-steel composite bars was constructed, and compared with the test results for analysis. The results showed that the stress-strain curves of the GFRP-steel composite bars exhibited obvious bilinear characteristics, and it still maintained a stable deformation resistance after the yielding of the inner core steel rebars. Furthermore, the theoretical model of stress-strain relations established in the paper matched well with the test results, demonstrating the effectiveness of the model in reflecting the tensile properties of the composite bars.
Tensile tests were conducted on a new type of GFRP-steel composite bars, the failure process and mechanical performance indicators of the composite bars were analyzed. A theoretical model of stress-strain relations for the new type of GFRP-steel composite bars was constructed, and compared with the test results for analysis. The results showed that the stress-strain curves of the GFRP-steel composite bars exhibited obvious bilinear characteristics, and it still maintained a stable deformation resistance after the yielding of the inner core steel rebars. Furthermore, the theoretical model of stress-strain relations established in the paper matched well with the test results, demonstrating the effectiveness of the model in reflecting the tensile properties of the composite bars.
2024, 54(4): 228-237.
doi: 10.3724/j.gyjzG23080905
Abstract:
The technique of grouted anchor rods with bushings is a new strengthening and repair technique that can be used for repairing mass brick masonry ancient buildings without damaging their appearance. In order to study the pull-out performance of grouted anchor rods inside historic masonry, pull-out tests on 21 anchor rods with the fullness of mortar joints, anchoring depth, drilling diameter and anchorage direction as research parameters were designed and completed, and the failure modes of anchor rods, pull-out force-slip curves, the distribution of anchor bar strains as well as interface bonding stresses and peak pull-out forces were analyzed. The test results showed that the pull-out force-slip curves of grouted anchor rods with bushings exhibited distinct four-stage characteristics; the anchor bars within the anchor rods showed resistance to yielding; the failure modes of anchor rods were directly affected by the fullness of mortar joints and the drilling diameter; the peak pull-out forces of anchor rods had a non-linear growth relation with the anchorage depth; the peak pull-out forces of anchor rods with high fullness of mortar joints and large drilling diameter were high; and compared with horizontal anchor rods, the peak pull-out forces of vertical anchor rods were significantly higher.
The technique of grouted anchor rods with bushings is a new strengthening and repair technique that can be used for repairing mass brick masonry ancient buildings without damaging their appearance. In order to study the pull-out performance of grouted anchor rods inside historic masonry, pull-out tests on 21 anchor rods with the fullness of mortar joints, anchoring depth, drilling diameter and anchorage direction as research parameters were designed and completed, and the failure modes of anchor rods, pull-out force-slip curves, the distribution of anchor bar strains as well as interface bonding stresses and peak pull-out forces were analyzed. The test results showed that the pull-out force-slip curves of grouted anchor rods with bushings exhibited distinct four-stage characteristics; the anchor bars within the anchor rods showed resistance to yielding; the failure modes of anchor rods were directly affected by the fullness of mortar joints and the drilling diameter; the peak pull-out forces of anchor rods had a non-linear growth relation with the anchorage depth; the peak pull-out forces of anchor rods with high fullness of mortar joints and large drilling diameter were high; and compared with horizontal anchor rods, the peak pull-out forces of vertical anchor rods were significantly higher.
2024, 54(4): 238-245.
doi: 10.3724/j.gyjzG23081811
Abstract:
The architectural heritage of railway stations is an important part of modern industrial heritage, and it is an important physical evidence to study the development history of modern architecture, industry and railway construction. There are some similarities in the history of modern industrial development between Japan and China, and the railway development of Japan has a certain influence on northeast China, which has important reference value for the study of the railway development history of China. This study took the architectural heritage of railway stations in Japan as the research object, sorted out the historical development context of the architectural heritage of railways and railway stations in Japan, collected and sorted out the basic information of all architectural heritage of railway stations in Japan, and investigated the style characteristics of each architectural heritage of railway stations. Based on the development of Japanese architectural thought and the cultural, technological, economic and other social factors when architectural heritage of railway stations were built, the paper analyzed and studied the design motivations of various types of architectural heritage of railway stations. The results are conducive to strengthening the research on the protection and regeneration of railway industrial heritage in China and Japan.
The architectural heritage of railway stations is an important part of modern industrial heritage, and it is an important physical evidence to study the development history of modern architecture, industry and railway construction. There are some similarities in the history of modern industrial development between Japan and China, and the railway development of Japan has a certain influence on northeast China, which has important reference value for the study of the railway development history of China. This study took the architectural heritage of railway stations in Japan as the research object, sorted out the historical development context of the architectural heritage of railways and railway stations in Japan, collected and sorted out the basic information of all architectural heritage of railway stations in Japan, and investigated the style characteristics of each architectural heritage of railway stations. Based on the development of Japanese architectural thought and the cultural, technological, economic and other social factors when architectural heritage of railway stations were built, the paper analyzed and studied the design motivations of various types of architectural heritage of railway stations. The results are conducive to strengthening the research on the protection and regeneration of railway industrial heritage in China and Japan.
