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2023 Vol. 53, No. 4
Display Method:
2023, 53(4): 1-7,74.
doi: 10.13204/j.gyjzG21100918
Abstract:
The construction of long-span power transmission lines in China is booming. These transmission lines run through large distances with high-rise towers, and are facing severe challenges from harsh environments. For construction of long-span and ultra high-rise transmission towers, the crane structure with double-flat-arm derrick has become the most important lifting equipment. During the construction process, the crane operates has to face the complex and extreme wind environment. The crane structure with a large slenderness ratio is quite wind-sensitive. Wind tunnel tests were carried out for the double-flat-arm derrick for erecting the 385 m high tower crossing the Yangtze River in Jiangyin. High-frequency force-balance wind tunnel tests were conducted for different working positions of flat arms under various incoming wind angles. The obtained shape coefficients of the standard tower body segment exihibited a linear relation with the incoming wind angles. It was also found that the overall shape coefficients of the crane structure obtained by the code might be risky, and should be paid more attention to the wind resistance calculation of the derrick structure. A refined wind loading calculation formula was proposed based on the member assembly method.
The construction of long-span power transmission lines in China is booming. These transmission lines run through large distances with high-rise towers, and are facing severe challenges from harsh environments. For construction of long-span and ultra high-rise transmission towers, the crane structure with double-flat-arm derrick has become the most important lifting equipment. During the construction process, the crane operates has to face the complex and extreme wind environment. The crane structure with a large slenderness ratio is quite wind-sensitive. Wind tunnel tests were carried out for the double-flat-arm derrick for erecting the 385 m high tower crossing the Yangtze River in Jiangyin. High-frequency force-balance wind tunnel tests were conducted for different working positions of flat arms under various incoming wind angles. The obtained shape coefficients of the standard tower body segment exihibited a linear relation with the incoming wind angles. It was also found that the overall shape coefficients of the crane structure obtained by the code might be risky, and should be paid more attention to the wind resistance calculation of the derrick structure. A refined wind loading calculation formula was proposed based on the member assembly method.
2023, 53(4): 8-14.
doi: 10.13204/j.gyjzG21070113
Abstract:
To investigate the vibration response characteristics of overhead transmission lines and the influence of icing and anti-vibration dampers, a typical long-span conductor was taken as the research object. The fluctuating wind model was established with the harmonic superposition method based on the theory of stochastic process, and then, the functional expression of natural wind load was obtained. The dynamic analysis of conductors was carried out by the general finite element software ANSYS. In the self-damping condition, the wind-induced vibration responses of bare conductor and ice-covered conductor were analyzed and compared. Finally, by simplifying the anti-vibration dampers as a spring vibrator, the dynamic response simulation was conducted on the system of ice-covered conductors and anti-vibration dampers, the effect of the multi-point centrally arranged dampers in controlling the vibration response of conductors was verified in both downwind and veritical wind directions.
To investigate the vibration response characteristics of overhead transmission lines and the influence of icing and anti-vibration dampers, a typical long-span conductor was taken as the research object. The fluctuating wind model was established with the harmonic superposition method based on the theory of stochastic process, and then, the functional expression of natural wind load was obtained. The dynamic analysis of conductors was carried out by the general finite element software ANSYS. In the self-damping condition, the wind-induced vibration responses of bare conductor and ice-covered conductor were analyzed and compared. Finally, by simplifying the anti-vibration dampers as a spring vibrator, the dynamic response simulation was conducted on the system of ice-covered conductors and anti-vibration dampers, the effect of the multi-point centrally arranged dampers in controlling the vibration response of conductors was verified in both downwind and veritical wind directions.
2023, 53(4): 15-21.
doi: 10.13204/j.gyjzG20121012
Abstract:
The capacity curves of lattice transmission towers under wind loading were first calculated based on current design codes. According to the stress characteristics of structural components, three performance indexes under the first-passage failure criterion were discussed by using the displacement angle of the tower top as an indicator. Then, these indexes were validated by implementing the statistical analysis based on the Latin Hypercube Sampling (LHS) of equivalent static calculation. Thirdly, the fragility curves under unfavorable wind directions were calculated with the uncertain characteristics of the vertex displacement angle. These results were validated with an overhead transmission line-tower system by using the first-passage failure theory. Wind speeds corresponding to the HCLPF (High Confidence, Low Probability of Failure) results showed that the results under different methods were very close to each other, but the LHS approach had higher calculation efficiency.
The capacity curves of lattice transmission towers under wind loading were first calculated based on current design codes. According to the stress characteristics of structural components, three performance indexes under the first-passage failure criterion were discussed by using the displacement angle of the tower top as an indicator. Then, these indexes were validated by implementing the statistical analysis based on the Latin Hypercube Sampling (LHS) of equivalent static calculation. Thirdly, the fragility curves under unfavorable wind directions were calculated with the uncertain characteristics of the vertex displacement angle. These results were validated with an overhead transmission line-tower system by using the first-passage failure theory. Wind speeds corresponding to the HCLPF (High Confidence, Low Probability of Failure) results showed that the results under different methods were very close to each other, but the LHS approach had higher calculation efficiency.
2023, 53(4): 22-28.
doi: 10.13204/j.gyjzG21042308
Abstract:
An outlet tunnel adjacent to multiple high-voltage towers will be constructed by borehole-blasting method. Based on this project a dynamic numerical calculation model with infinite element boundary under blasting dynamic load was established. The characteristics of the dynamic response for high-voltage transmission towers were studied, and the attenuation law of the surrounding rock vibration velocity was also discussed. Then the proposed construction schemes were evaluated and optimized in accordance with the corresponding specifications. The research results showed that the infinite element boundary could better reflect the actual situation of the blasting energy propagating to the semi-infinite medium and avoid oscillations in the computing domain. Under the action of the blasting load, the resultant vibration velocity of the surrounding rock decreased with the increase of the distance from the blasting center. Based on the corresponding specifications, a 2.0 cm/s peak vibration velocity was selected as the safety criterion, and the critical safety distances of the three proposed blasting construction schemes were determined. Furthermore, in consideration of the surrounding rock engineering characteristics of the outlet tunnel and the relative position of the high-voltage tower, the respective working area for the three blasting construction schemes was clarified and optimized.
An outlet tunnel adjacent to multiple high-voltage towers will be constructed by borehole-blasting method. Based on this project a dynamic numerical calculation model with infinite element boundary under blasting dynamic load was established. The characteristics of the dynamic response for high-voltage transmission towers were studied, and the attenuation law of the surrounding rock vibration velocity was also discussed. Then the proposed construction schemes were evaluated and optimized in accordance with the corresponding specifications. The research results showed that the infinite element boundary could better reflect the actual situation of the blasting energy propagating to the semi-infinite medium and avoid oscillations in the computing domain. Under the action of the blasting load, the resultant vibration velocity of the surrounding rock decreased with the increase of the distance from the blasting center. Based on the corresponding specifications, a 2.0 cm/s peak vibration velocity was selected as the safety criterion, and the critical safety distances of the three proposed blasting construction schemes were determined. Furthermore, in consideration of the surrounding rock engineering characteristics of the outlet tunnel and the relative position of the high-voltage tower, the respective working area for the three blasting construction schemes was clarified and optimized.
2023, 53(4): 29-34,93.
doi: 10.13204/j.gyjzG22070403
Abstract:
The stress state and collapse cause of transmission tower of 500 kV Zhangquan line II under the combined action of wind speed, wind direction, and micro terrain wind speed-up ratio were studied when Typhoon Meranti passed Xiamen. Based on the historical meteorological data and the destruction pattern of the tower, the input conditions of wind speed and direction which were most likely to cause the tower to collapse were determined. Based on CFD simulation analysis, the wind speed-up ratio of 24 wind angles at the inverted tower position was determined, and the stress of main members and inclined members under two wind angles conforming to the site failure pattern was analyzed, and the internal relation between the failure pattern of transmission tower and wind speed, wind direction and wind speed-up ratio were clarified. The influence of wind speed, wind direction and wind speed-up ratio which widely existing in mountainous region should be considered comprehensively in the design of Fujian coastal high-voltage transmission line to against typhoon.
The stress state and collapse cause of transmission tower of 500 kV Zhangquan line II under the combined action of wind speed, wind direction, and micro terrain wind speed-up ratio were studied when Typhoon Meranti passed Xiamen. Based on the historical meteorological data and the destruction pattern of the tower, the input conditions of wind speed and direction which were most likely to cause the tower to collapse were determined. Based on CFD simulation analysis, the wind speed-up ratio of 24 wind angles at the inverted tower position was determined, and the stress of main members and inclined members under two wind angles conforming to the site failure pattern was analyzed, and the internal relation between the failure pattern of transmission tower and wind speed, wind direction and wind speed-up ratio were clarified. The influence of wind speed, wind direction and wind speed-up ratio which widely existing in mountainous region should be considered comprehensively in the design of Fujian coastal high-voltage transmission line to against typhoon.
2023, 53(4): 35-40.
doi: 10.13204/j.gyjzG21113012
Abstract:
Based on the long-span transmission tower of 500 kV Fengcheng to Meili project, the selection of the joint of bottom-crossarm compression members was conducted. Three types of joints were put forward and compared, including tubular welding joint, welded hollow spherical joint and cast steel tubular joint. Monolithic casting technique was adopted in cast steel joints, it could solve the problem of space intersection of multiple members, and avoid complex welding process. Based on the comparison results, the cast steel joint was selected, and the steel material was G20Mn5QT. Then, the nonlinear finite element analysis was performed, the stress characteristics and ultimate bearing capacity of the cast steel joint were investigated, and the design bearing capacity of the joint under different load cases was calculated. The resules showed that the cast steel joint was safe and reliable, which could be wildly used in super high-rise transmission towers.
Based on the long-span transmission tower of 500 kV Fengcheng to Meili project, the selection of the joint of bottom-crossarm compression members was conducted. Three types of joints were put forward and compared, including tubular welding joint, welded hollow spherical joint and cast steel tubular joint. Monolithic casting technique was adopted in cast steel joints, it could solve the problem of space intersection of multiple members, and avoid complex welding process. Based on the comparison results, the cast steel joint was selected, and the steel material was G20Mn5QT. Then, the nonlinear finite element analysis was performed, the stress characteristics and ultimate bearing capacity of the cast steel joint were investigated, and the design bearing capacity of the joint under different load cases was calculated. The resules showed that the cast steel joint was safe and reliable, which could be wildly used in super high-rise transmission towers.
2023, 53(4): 41-45.
doi: 10.13204/j.gyjzG22011406
Abstract:
Wind disaster vulnerability study was carried out to evaluate the reliability of high-rise lightning rods in substations, due to the accidents induced by wind storms, in which a representative high-rise lightning rod was selected as an example. Latin hypercube sampling and fluctuating wind field simulation were adopted to generate structure samples and wind velocity history samples to incorporate their randomness simultaneously. Static pushover analysis and incremental dynamic time-history analysis, both considering the material nonlinearity, were conducted to obtain the static and dynamic responses respectively. The performance quantized values of four different damage levels were determined according to the top displacement. The valuerability curve was obtained through regression analysis of structural response requiements and load intensity, as well as the vulnarability function, so as to clarify the wind resistance of the structure. In addition, the regression analysis method was discussed in the fitting of the structural response requrements and load intensity, it was found that the double logarithmic form was more reasonable.
Wind disaster vulnerability study was carried out to evaluate the reliability of high-rise lightning rods in substations, due to the accidents induced by wind storms, in which a representative high-rise lightning rod was selected as an example. Latin hypercube sampling and fluctuating wind field simulation were adopted to generate structure samples and wind velocity history samples to incorporate their randomness simultaneously. Static pushover analysis and incremental dynamic time-history analysis, both considering the material nonlinearity, were conducted to obtain the static and dynamic responses respectively. The performance quantized values of four different damage levels were determined according to the top displacement. The valuerability curve was obtained through regression analysis of structural response requiements and load intensity, as well as the vulnarability function, so as to clarify the wind resistance of the structure. In addition, the regression analysis method was discussed in the fitting of the structural response requrements and load intensity, it was found that the double logarithmic form was more reasonable.
2023, 53(4): 46-53,45.
doi: 10.13204/j.gyjzG21090704
Abstract:
In order to solve the problem that pedestrians are easy to lose their bearings in underground rail stations, the relevant theories based on pedestrian needs and spatial syntax were studied, and three evaluation indexes were proposed: accessibility obtained by analyzing spatial topological relations, visibility obtained by spatially horizontal relations and walking distance obtained by measuring spatial distance, combined with the survey data, the pedestrian perception in underground rail stations was quantitatively analyzed. Taking Nanjing Xinjiekou Underground Rail Station as an example, the application of the evaluation method in the actual case was illustrated, and some optimization strategies were proposed, such as enhancing spatial continuity, optimizing exit perceptibility, reducing the excessive core space, and reasonably arranging the platform floors.
In order to solve the problem that pedestrians are easy to lose their bearings in underground rail stations, the relevant theories based on pedestrian needs and spatial syntax were studied, and three evaluation indexes were proposed: accessibility obtained by analyzing spatial topological relations, visibility obtained by spatially horizontal relations and walking distance obtained by measuring spatial distance, combined with the survey data, the pedestrian perception in underground rail stations was quantitatively analyzed. Taking Nanjing Xinjiekou Underground Rail Station as an example, the application of the evaluation method in the actual case was illustrated, and some optimization strategies were proposed, such as enhancing spatial continuity, optimizing exit perceptibility, reducing the excessive core space, and reasonably arranging the platform floors.
2023, 53(4): 54-61.
doi: 10.13204/j.gyjzG22010419
Abstract:
Low-impact development (LID) in the external environment of buildings is an important way to achieve efficient urban runoff control and rainwater resource utilization, however, there are some problems in the distribution of LID controls, such as excessive facility scale and low runoff utilization efficiency, which cause construction waste. Based on the runoff characteristics of the external environment of the building and the functional guidance characteristics of different LID controls, an economical design pattern of low-impact development in external environment of building was formed with SWMM model and NSGA-II algorithm, which took into account runoff control, rainwater resource utilization and cost of LID controls. Taking the campus of Nanyang No. 1 High School as the experimental object, the optimal distribution of LID controls was obtained by the design pattern, and its effect was quantified by simulation based on 2021 daily precipitation. The results showed that the annual runoff control ratio of the experimental object was 82.0%, and 51 900 yuan of water could be saved in 2021. The research results refined the application scenario of LID controls distribution, made up for the lack of traditional low-impact development that ignored quantification of rainwater utilization and LID controls cost, improved the optimization of the investment in LID controls construction, and promoted the high-performance and high-quality construction of "Sponge City".
Low-impact development (LID) in the external environment of buildings is an important way to achieve efficient urban runoff control and rainwater resource utilization, however, there are some problems in the distribution of LID controls, such as excessive facility scale and low runoff utilization efficiency, which cause construction waste. Based on the runoff characteristics of the external environment of the building and the functional guidance characteristics of different LID controls, an economical design pattern of low-impact development in external environment of building was formed with SWMM model and NSGA-II algorithm, which took into account runoff control, rainwater resource utilization and cost of LID controls. Taking the campus of Nanyang No. 1 High School as the experimental object, the optimal distribution of LID controls was obtained by the design pattern, and its effect was quantified by simulation based on 2021 daily precipitation. The results showed that the annual runoff control ratio of the experimental object was 82.0%, and 51 900 yuan of water could be saved in 2021. The research results refined the application scenario of LID controls distribution, made up for the lack of traditional low-impact development that ignored quantification of rainwater utilization and LID controls cost, improved the optimization of the investment in LID controls construction, and promoted the high-performance and high-quality construction of "Sponge City".
2023, 53(4): 62-66,21.
doi: 10.13204/j.gyjzG21020501
Abstract:
Recent scholarship of narrative geography has focused on the spatial narratives of memorial landscapes of earthquakes. The study aimed to reveal the issues of processes, strategies, and types of landscape narratives in open and closed spaces by focusing on the memorial landscapes at the Donghekou Site Park of the 2008 Earthquake in Qingchuan. The results identified three kinds of narrative strategies, ranging from point narrative and sequential narrative to hybrid narrative, which were further divided into 10 sub-types, such as spatial narratives of markers, plazas, and the Donghekou story village. The point narrative and sequential narrative had set the spatial configuration of the site to three narrative lines related with memorial landscapes, and these included "Commemorate Victims", "Explore Ruins", and "Visit Rebuilt Sites". Ultimately, the spatial narratives of memorial landscapes of the earthquake exalted the core value of the site park, which could be manifested as "to remember the earthquake disaster and to look into the future".
Recent scholarship of narrative geography has focused on the spatial narratives of memorial landscapes of earthquakes. The study aimed to reveal the issues of processes, strategies, and types of landscape narratives in open and closed spaces by focusing on the memorial landscapes at the Donghekou Site Park of the 2008 Earthquake in Qingchuan. The results identified three kinds of narrative strategies, ranging from point narrative and sequential narrative to hybrid narrative, which were further divided into 10 sub-types, such as spatial narratives of markers, plazas, and the Donghekou story village. The point narrative and sequential narrative had set the spatial configuration of the site to three narrative lines related with memorial landscapes, and these included "Commemorate Victims", "Explore Ruins", and "Visit Rebuilt Sites". Ultimately, the spatial narratives of memorial landscapes of the earthquake exalted the core value of the site park, which could be manifested as "to remember the earthquake disaster and to look into the future".
2023, 53(4): 67-74.
doi: 10.13204/j.gyjzG22061308
Abstract:
The protection and renewal of industrial heritage plays an important role in the inheritance of urban history and culture, and is also a valuable space resource in the process of urban development and transformation. Based on the methods of network text analysis, business type analysis and spatial syntax analysis, this paper evaluated the public perception of heritage value, the suitability of function transformation, and the visibility of heritage value after spatial reorganization for the industrial heritage protection and renewal project of Jinling Machinery Bureau. The effectiveness and improvement methods of value inheritance in the renewal and utilization of industrial heritage were explored, which could provide a reference for other cases of industrial heritage renewal and transformation.
The protection and renewal of industrial heritage plays an important role in the inheritance of urban history and culture, and is also a valuable space resource in the process of urban development and transformation. Based on the methods of network text analysis, business type analysis and spatial syntax analysis, this paper evaluated the public perception of heritage value, the suitability of function transformation, and the visibility of heritage value after spatial reorganization for the industrial heritage protection and renewal project of Jinling Machinery Bureau. The effectiveness and improvement methods of value inheritance in the renewal and utilization of industrial heritage were explored, which could provide a reference for other cases of industrial heritage renewal and transformation.
2023, 53(4): 75-82.
doi: 10.13204/j.gyjzG22060807
Abstract:
The heritage of the petroleum industry has witnessed the development of urban industrial culture, and is the epitome of the industrial civilization development of a city. As a link between the public and the heritage site, industrial heritage interpretation is the most widely-used way to interpret and protect heritage. By analyzing the characteristics of petroleum industrial heritage and the problems existing in the interpretation of cultural heritage, the theory of situational interpretation was introduced, and the way of interpreting heritage through the construction of heritage context was proposed. In addition, with the help of digital visualization, the historical context of the heritage was recreated, and the heritage was placed into a specific historical context for interpretation. Taking Daqing’s Sa-55 well as the research object,and the contextual interpretation method was used to resolve the situation of the oil production scene from the macro and micro dimensions of the heritage, hoping to provide a reference for the establishment of the situational interpretation model of the heritage.
The heritage of the petroleum industry has witnessed the development of urban industrial culture, and is the epitome of the industrial civilization development of a city. As a link between the public and the heritage site, industrial heritage interpretation is the most widely-used way to interpret and protect heritage. By analyzing the characteristics of petroleum industrial heritage and the problems existing in the interpretation of cultural heritage, the theory of situational interpretation was introduced, and the way of interpreting heritage through the construction of heritage context was proposed. In addition, with the help of digital visualization, the historical context of the heritage was recreated, and the heritage was placed into a specific historical context for interpretation. Taking Daqing’s Sa-55 well as the research object,and the contextual interpretation method was used to resolve the situation of the oil production scene from the macro and micro dimensions of the heritage, hoping to provide a reference for the establishment of the situational interpretation model of the heritage.
2023, 53(4): 94-101.
doi: 10.13204/j.gyjzG22052611
Abstract:
A pressure measurement test was conducted on a special-shaped curved roof in the atmospheric boundary layer wind tunnel, and the time series of fluctuating wind loads on the roof surface was obtained. The skewness, kurtosis, probability density, correlation coefficient and coherence of fluctuating wind pressure on the roof were analyzed. The peak factor method and Sadek-Simiu method were used to evaluate the peak factors of typical measurement points in the non-Gaussian regions. The results indicated that the skewness, kurtosis and probability density function of the fluctuating wind pressure at the leading edge of the roof and the place where the radian changed greatly was significantly different from the Gaussian distribution, and had obvious non-Gaussian characteristics. The correlation coefficients of measurement points decreased with the increase of distance between measurement points, and the correlation coefficients of measurement points at edges were higher than that of measurment points in the middle. The coherence of fluctuating wind pressure decreased with the increase of frequencies in the low frequency band, and the coherence maintained about 0.2 in the high frequency band. The coherence decreased with the increase of distance between measurement points. The peak factors obtained by Sadek-Simiu method could more safely estimate the extreme wind pressure of measurement points in the non-Gaussian region.
2023, 53(4): 102-107,147.
doi: 10.13204/j.gyjzG20122208
Abstract:
The influence of concrete reinforced with fibers in the post-cast region, including the connection region and beam service holes, was studied. An improved precast prestressed beam-column connection was designed by using fiber modified concrete in the connection area. For specimen SJ1 and SJ4, the influence of design parameters on the mechanical properties of connections was investigated systematically, which including the ductility and strength of concrete in the post-cast region, beam longitudinal rebar strength, and stirrup spacing in the post-cast region. The results showed that the reduction of compressive ductility of post-cast concrete had a more obvious promoting effect on the accelerated degradation of the connection strength and the reduction of displacement ductility of connections with a high reinforcement ratio. By increasing the strength grade of beam longitudinal rebars, the bearing capacity of connections would be improved significantly, while there was a drop in the displacement ductility. The displacement ductility of connections decreased with enlarging the stirrup spacing in the post-cast region. Moreover, the seismic performance of the connections with a high reinforcement ratio were more sensitive to the increase of the stirrup spacing of post-cast region.
The influence of concrete reinforced with fibers in the post-cast region, including the connection region and beam service holes, was studied. An improved precast prestressed beam-column connection was designed by using fiber modified concrete in the connection area. For specimen SJ1 and SJ4, the influence of design parameters on the mechanical properties of connections was investigated systematically, which including the ductility and strength of concrete in the post-cast region, beam longitudinal rebar strength, and stirrup spacing in the post-cast region. The results showed that the reduction of compressive ductility of post-cast concrete had a more obvious promoting effect on the accelerated degradation of the connection strength and the reduction of displacement ductility of connections with a high reinforcement ratio. By increasing the strength grade of beam longitudinal rebars, the bearing capacity of connections would be improved significantly, while there was a drop in the displacement ductility. The displacement ductility of connections decreased with enlarging the stirrup spacing in the post-cast region. Moreover, the seismic performance of the connections with a high reinforcement ratio were more sensitive to the increase of the stirrup spacing of post-cast region.
2023, 53(4): 108-114,40.
doi: 10.13204/j.gyjzG22042810
Abstract:
Taking a high-rise multi-tower interconnected structure in Zhuhai as an example, the surface wind pressure characteristics and shape coefficient distribution of complex high-connected multi-tower structures were studied, which could provide the calculation basis for the wind-resistant design of such structures to ensure the structural safety. CFD method was used to conduct numerical wind tunnel simulation of the high-rise multi-tower interconnected structure and surrounding disturbed buildings. The shape coefficients of main surfaces and local structures under different wind direction angles were analyzed, and compared with the physical wind tunnel test results and standard values of the load code. The shape coefficients of windward side of the structure was generally large in the middle and small on both sides, and there was interaction between multiple towers. On the podium, the larger absolute value of shape coefficients might be exist, and the oblique flow was easy to form larger wind pressure on the adjacent surfaces. Compared with the physical wind tunnel test results, the numerical simulation results were closer to the values of the load code, and the distribution was relatively more uniform. The concave surface of the high-altitude irregular connector produced larger shape coefficients, however, the influence on the whole structure was limited. In the wind-resistant design process, the interference between multiple towers and the influence of high-altitude irregular connectors should be considered.
Taking a high-rise multi-tower interconnected structure in Zhuhai as an example, the surface wind pressure characteristics and shape coefficient distribution of complex high-connected multi-tower structures were studied, which could provide the calculation basis for the wind-resistant design of such structures to ensure the structural safety. CFD method was used to conduct numerical wind tunnel simulation of the high-rise multi-tower interconnected structure and surrounding disturbed buildings. The shape coefficients of main surfaces and local structures under different wind direction angles were analyzed, and compared with the physical wind tunnel test results and standard values of the load code. The shape coefficients of windward side of the structure was generally large in the middle and small on both sides, and there was interaction between multiple towers. On the podium, the larger absolute value of shape coefficients might be exist, and the oblique flow was easy to form larger wind pressure on the adjacent surfaces. Compared with the physical wind tunnel test results, the numerical simulation results were closer to the values of the load code, and the distribution was relatively more uniform. The concave surface of the high-altitude irregular connector produced larger shape coefficients, however, the influence on the whole structure was limited. In the wind-resistant design process, the interference between multiple towers and the influence of high-altitude irregular connectors should be considered.
Experimental Research on Fatigue Life of Composite Beams with Laminated Slabs and Z2 Fatigue Details
2023, 53(4): 115-119,28.
doi: 10.13204/j.gyjzG22012509
Abstract:
In order to popularize the prefabrication construction technology and the application of steel-concrete composite beams in bridge structures and crane beams, it is necessary to carry out experimental research on fatigue life of composite beams with various structural details. 6 composite beams (including 5 composite beams with laminated slabs and 1 composite beam with cast-in-place slabs) were subjected to constant amplitude fatigue load. The double logarithm function was used to linearly fit the test data of 5 composite beams with Z2 structural details, and the S-N curve was obtained. The test results were very close to the provisions of European Convention for Constructional Steelwork (ECCS) and in good agreement with Code for Design of Steel Structures (GB 50017—2003), but there was a certain deviation from GB 50017—2017, mainly because their classifications of structural details were different. The adoption to GB 50017—2017 were unsafe. At this stage, it was recommended to review the design of composite beams in accordance with the relevant provisions of GB 50017—2003.
In order to popularize the prefabrication construction technology and the application of steel-concrete composite beams in bridge structures and crane beams, it is necessary to carry out experimental research on fatigue life of composite beams with various structural details. 6 composite beams (including 5 composite beams with laminated slabs and 1 composite beam with cast-in-place slabs) were subjected to constant amplitude fatigue load. The double logarithm function was used to linearly fit the test data of 5 composite beams with Z2 structural details, and the S-N curve was obtained. The test results were very close to the provisions of European Convention for Constructional Steelwork (ECCS) and in good agreement with Code for Design of Steel Structures (GB 50017—2003), but there was a certain deviation from GB 50017—2017, mainly because their classifications of structural details were different. The adoption to GB 50017—2017 were unsafe. At this stage, it was recommended to review the design of composite beams in accordance with the relevant provisions of GB 50017—2003.
2023, 53(4): 120-124,179.
doi: 10.13204/j.gyjzG21100816
Abstract:
To determine the bond length and configuration of high-strength Q420 steel pipe joint for prefabricated composite structural columns, including the pipe sections of ϕ114×25, ϕ152×16 and ϕ194×10, push-out tests were conducted. The different bond lengths (600 mm and 800 mm), different bond materials (C35 concrete and M50 grout) and the setting of spiral rebars ϕ6@50 were considered. By comparing and analyzing the load displacement/slippage curves as well as bond strengths, the interfacial bond performance of steel pipe joints was discussed. The test and analysis results showed that 600 mm bond length could ensure that the joint had bond strength that could meet the requirements of the specification. The increase of bond length could delay the slip, but the bond strength decreased. The high-strength grout obviously increased the peak load, and had no obvious effect on the trend of the curve. The influence of slenderness ratio and diameter thickness ratio were not obvious. Under the same conditions, ϕ114×25 steel pipe could obtain the highest bond strength. Spiral rebars could effectively improve the bond strength and delay the interface slip,which should be recommended in engineering, due to its good behavior and easy construction.
To determine the bond length and configuration of high-strength Q420 steel pipe joint for prefabricated composite structural columns, including the pipe sections of ϕ114×25, ϕ152×16 and ϕ194×10, push-out tests were conducted. The different bond lengths (600 mm and 800 mm), different bond materials (C35 concrete and M50 grout) and the setting of spiral rebars ϕ6@50 were considered. By comparing and analyzing the load displacement/slippage curves as well as bond strengths, the interfacial bond performance of steel pipe joints was discussed. The test and analysis results showed that 600 mm bond length could ensure that the joint had bond strength that could meet the requirements of the specification. The increase of bond length could delay the slip, but the bond strength decreased. The high-strength grout obviously increased the peak load, and had no obvious effect on the trend of the curve. The influence of slenderness ratio and diameter thickness ratio were not obvious. Under the same conditions, ϕ114×25 steel pipe could obtain the highest bond strength. Spiral rebars could effectively improve the bond strength and delay the interface slip,which should be recommended in engineering, due to its good behavior and easy construction.
2023, 53(4): 125-130,140.
doi: 10.13204/j.gyjzG23010601
Abstract:
In order to study the structure and bearing capacity of lightweight high-strength truss joints, static loading tests were carried out on X-joints with stiffened plates and basic X-joints of lightweight aggregate (LWA) concrete-filled Q345B steel square tubes. The effects of the stiffened plates between braces and chords and the LWA concrete poured into braces and chords on the failure mode and bearing capacity of X-joints were studied. Tests results showed that the failure modes of stiffened X-joints were weld cracking between stiffened plates and braces under shear and compression, tension failure of brace flange under shear and compression by stiffened plates, and shear and compression failure at sections of braces under shear and compression near stiffened plate outer edge. The failure mode of the basic X-joints was weld cracking between braces and chords. The yield and fracture process of X-joints were delayed and the bearing capacity of X-joints increased significantly due to the stiffened plates between braces and chords. Pouring LWA concrete into braces and chords could effectively prevent buckling of square steel tubes. The weld cracking load and the bearing capacity of stiffened X-joints were 63.3% and 18.3%, respectively, which were higher than those of the basic X-joints. According to the failure modes of stiffened X-joints, the calculation models were established and the bearing capacity calculation formulas were derived considering the effects of stress transfer and diffusion of stiffened plates for fracture of fillets between stiffened plates and braces under shear and compression, flange pulling of shear-pressure braces, shear-compression failure of shear-pressure braces of stiffened X-joints of lightweight aggregate concrete-filled high-strength square steel tubes. The calculation error of the suggested bearing capacity formula for stiffened X-joints was -27.8% to +3.7%.
In order to study the structure and bearing capacity of lightweight high-strength truss joints, static loading tests were carried out on X-joints with stiffened plates and basic X-joints of lightweight aggregate (LWA) concrete-filled Q345B steel square tubes. The effects of the stiffened plates between braces and chords and the LWA concrete poured into braces and chords on the failure mode and bearing capacity of X-joints were studied. Tests results showed that the failure modes of stiffened X-joints were weld cracking between stiffened plates and braces under shear and compression, tension failure of brace flange under shear and compression by stiffened plates, and shear and compression failure at sections of braces under shear and compression near stiffened plate outer edge. The failure mode of the basic X-joints was weld cracking between braces and chords. The yield and fracture process of X-joints were delayed and the bearing capacity of X-joints increased significantly due to the stiffened plates between braces and chords. Pouring LWA concrete into braces and chords could effectively prevent buckling of square steel tubes. The weld cracking load and the bearing capacity of stiffened X-joints were 63.3% and 18.3%, respectively, which were higher than those of the basic X-joints. According to the failure modes of stiffened X-joints, the calculation models were established and the bearing capacity calculation formulas were derived considering the effects of stress transfer and diffusion of stiffened plates for fracture of fillets between stiffened plates and braces under shear and compression, flange pulling of shear-pressure braces, shear-compression failure of shear-pressure braces of stiffened X-joints of lightweight aggregate concrete-filled high-strength square steel tubes. The calculation error of the suggested bearing capacity formula for stiffened X-joints was -27.8% to +3.7%.
2023, 53(4): 131-135.
doi: 10.13204/j.gyjzG22050705
Abstract:
The ultimate bearing capacity of rock foundation is a widely discussed and researched subject in the field of rock mechanics. A finite element model was constructed by MIDAS/GTS Software based on Hoek-Brown Criterion. According to different geo-mechanical indexes, rock mechanical parameters, disturbance factors, ratios of distance form edges of fundations near slopes to width of froundations, and slope angles, the ultimate bearing capacity of rock foundation under strip foundations was explored. The results indicated that: 1) based on Hoek-Brown Criterion, the numerical model of rock foundation close to slopes was constructed by the finite element software MIDAS/GTS according to plane strain. The method for calculating the ultimate bearing capacity of rock foundation under strip foundations close to slopes was reliable; 2) a dimensionless parameter Nσ was defined to measure the influence of slopes on the ultimate bearing capacity of rock foundation. Nσ increased with the increase of the geo-mechanical indexes, and decreased with the increase of the disturbance factor. 3) With the increase of the slope top distance, Nσ gradually increased, but the corresponding Nσ at different slope angles were increasingly similar. Finally, the ultimate bearing capacity of rock foundation close to slopes gradually approached the ultimate bearing capacity of horizontal rock foundation; 4) with the decrease of slope angles, Nσ gradually increased, but Nσ in different ratios of distance from edges of foundetions near slopes to width of foundations were increasingly similar. Finally, the ultimate bearing capacity of rock foundation close to slopes gradually approached the ultimate bearing capacity of horizontal rock foundation.
The ultimate bearing capacity of rock foundation is a widely discussed and researched subject in the field of rock mechanics. A finite element model was constructed by MIDAS/GTS Software based on Hoek-Brown Criterion. According to different geo-mechanical indexes, rock mechanical parameters, disturbance factors, ratios of distance form edges of fundations near slopes to width of froundations, and slope angles, the ultimate bearing capacity of rock foundation under strip foundations was explored. The results indicated that: 1) based on Hoek-Brown Criterion, the numerical model of rock foundation close to slopes was constructed by the finite element software MIDAS/GTS according to plane strain. The method for calculating the ultimate bearing capacity of rock foundation under strip foundations close to slopes was reliable; 2) a dimensionless parameter Nσ was defined to measure the influence of slopes on the ultimate bearing capacity of rock foundation. Nσ increased with the increase of the geo-mechanical indexes, and decreased with the increase of the disturbance factor. 3) With the increase of the slope top distance, Nσ gradually increased, but the corresponding Nσ at different slope angles were increasingly similar. Finally, the ultimate bearing capacity of rock foundation close to slopes gradually approached the ultimate bearing capacity of horizontal rock foundation; 4) with the decrease of slope angles, Nσ gradually increased, but Nσ in different ratios of distance from edges of foundetions near slopes to width of foundations were increasingly similar. Finally, the ultimate bearing capacity of rock foundation close to slopes gradually approached the ultimate bearing capacity of horizontal rock foundation.
2023, 53(4): 136-140.
doi: 10.13204/j.gyjzG22062002
Abstract:
In order to solve the problem of service safety of parallel support systems in deep foundation excavation, the failure mode of concrete supports in parallel support systems in deep excavation engineering was analyzed. Taking the deep excavation project of Xiaoying Station in Zhengzhou Metro Line 8 as the object, based on the structural reliability analysis theory and failure probability theory, the safety state model of parallel support systems in deep excavation was constructed, and the design of concrete supports was "optimized by decore". The problem that measured values of concrete supports were far beyond theoretical values was effectively solved. Combined with the in-situ experiments, it was indicated that the factors influencing the failure probability of parallel support systems were related to supports with higher probability weight in support systems. A number of materials used in larger and smaller concrete support sections after decore optimization was reduced by about 8.5% and 11.9% respectively, and the construction cost was greatly saved.
In order to solve the problem of service safety of parallel support systems in deep foundation excavation, the failure mode of concrete supports in parallel support systems in deep excavation engineering was analyzed. Taking the deep excavation project of Xiaoying Station in Zhengzhou Metro Line 8 as the object, based on the structural reliability analysis theory and failure probability theory, the safety state model of parallel support systems in deep excavation was constructed, and the design of concrete supports was "optimized by decore". The problem that measured values of concrete supports were far beyond theoretical values was effectively solved. Combined with the in-situ experiments, it was indicated that the factors influencing the failure probability of parallel support systems were related to supports with higher probability weight in support systems. A number of materials used in larger and smaller concrete support sections after decore optimization was reduced by about 8.5% and 11.9% respectively, and the construction cost was greatly saved.
2023, 53(4): 141-147.
doi: 10.13204/j.gyjzG22050701
Abstract:
The numerical model of earth-reinforced retaining walls was constructed by FLAC3D, and on the basis of verifying the effectiveness of the model, by adjusting inclination angles of walls, the influence of inclination angles of walls on the lateral deformation, earth pressure and tension of rebars of modular earth-reinforced retaining walls was analyzed. The results indicated that when the inclination angles of walls decreased from 90° to 65°, the lateral deformation, earth pressure and tension of rebars in modular earth-reinforced retaining walls decreasd; the lateral deformation mode changed from the type of outward tilt translation to the type of translation and the type of translation-bulge; the distribution law of horizontal earth pressure behind panels along wall height changed from linear to nonlinear, and there was a linear relation between the peak tension of rebars in walls and the inclination angles of walls; the tension of rebars at connections between rebars and modules exhibited an exponential relation between inclination angles of walls; the inclination angle of 75° was reasonable for modular earth-reinforced retaining walls, which could not only facilitate the greening of walls, but also reduce the deformation of the walls and improve the stability of walls.
The numerical model of earth-reinforced retaining walls was constructed by FLAC3D, and on the basis of verifying the effectiveness of the model, by adjusting inclination angles of walls, the influence of inclination angles of walls on the lateral deformation, earth pressure and tension of rebars of modular earth-reinforced retaining walls was analyzed. The results indicated that when the inclination angles of walls decreased from 90° to 65°, the lateral deformation, earth pressure and tension of rebars in modular earth-reinforced retaining walls decreasd; the lateral deformation mode changed from the type of outward tilt translation to the type of translation and the type of translation-bulge; the distribution law of horizontal earth pressure behind panels along wall height changed from linear to nonlinear, and there was a linear relation between the peak tension of rebars in walls and the inclination angles of walls; the tension of rebars at connections between rebars and modules exhibited an exponential relation between inclination angles of walls; the inclination angle of 75° was reasonable for modular earth-reinforced retaining walls, which could not only facilitate the greening of walls, but also reduce the deformation of the walls and improve the stability of walls.
2023, 53(4): 148-153,61.
doi: 10.13204/j.gyjzG22082207
Abstract:
In order to study the effect of exposed aggregate treatment on the compression-shear bearing capacity of concrete specimens, 120 specimens with exposed aggregate treatment on the joint surface and 30 whole cast specimens were designed. Based on the laser scanning technology to obtain the bond surface morphology information, the roughness characterization parameters were obtained through programming; the shear test fixture designed independently was used to carry out the compression-shear load capacity test, and the change law of compression-shear bearing capacity parameters such as cohesion and internal friction angle of concrete bond surface with different roughness under the treatment of exposed aggregates was obtained. The results showed that the shear strength of the specimen could be improved by proper treatment of exposed aggregate on the joint surface, but excessive treatment would reduce its shear strength; the two-dimensional roughness parameters obtained based on laser scanning technology could be used to characterize the shear strength of the exposed aggregate specimen; the parameters of shear bearing capacity of the specimen were not significantly improved by increasing the strength of the post-casting concrete layer; the parameters of shear bearing capacity of the exposed aggregate specimen were somewhat different from those of the one-piece casting specimen, and the treatment process of the exposed aggregate on the joint surface could not fully meet the requirements equivalent to the one-piece casting yet.
In order to study the effect of exposed aggregate treatment on the compression-shear bearing capacity of concrete specimens, 120 specimens with exposed aggregate treatment on the joint surface and 30 whole cast specimens were designed. Based on the laser scanning technology to obtain the bond surface morphology information, the roughness characterization parameters were obtained through programming; the shear test fixture designed independently was used to carry out the compression-shear load capacity test, and the change law of compression-shear bearing capacity parameters such as cohesion and internal friction angle of concrete bond surface with different roughness under the treatment of exposed aggregates was obtained. The results showed that the shear strength of the specimen could be improved by proper treatment of exposed aggregate on the joint surface, but excessive treatment would reduce its shear strength; the two-dimensional roughness parameters obtained based on laser scanning technology could be used to characterize the shear strength of the exposed aggregate specimen; the parameters of shear bearing capacity of the specimen were not significantly improved by increasing the strength of the post-casting concrete layer; the parameters of shear bearing capacity of the exposed aggregate specimen were somewhat different from those of the one-piece casting specimen, and the treatment process of the exposed aggregate on the joint surface could not fully meet the requirements equivalent to the one-piece casting yet.
2023, 53(4): 154-160,172.
doi: 10.13204/j.gyjzG22063018
Abstract:
The damage deterioration law and crack repair mechanism of concrete under different humidity environments were systematically studied by the changes of apparent morphological characteristics, gas permeability, moisture transport and compressive strength, and the incentive mechanism of environmental responsive polymeric repair agents on the self-healing of damaged concrete under different humidity environments was revealed; meanwhile, the microstructure and evolution mechanism of crack self-healing were studied by combining scanning electron microscopy, energy spectrum analysis and X-ray diffraction. The microstructure and evolution mechanism of crack self-healing were also investigated by combining scanning electron microscopy, energy spectrum analysis and X-ray diffraction. The results showed that the natural air and 30% relative humidity curing environment were not conducive to the self-healing behavior of concrete cracks; with the increase of curing humidity, the concrete crack repair rate increased continuously, and the humid environment was favorable for the environmentally responsive polymeric repair agent to give full play to the stimulating effect, promote the crack self-healing characteristics, and prolong the service life; the best repair effect of polymeric repair agent was achieved under the water immersion environment, and the crack healing rate could reach 70.38%, the durability and compressive strength of the repaired concrete were significantly better than those of plain concrete.The main reason for crack healing was that the repair agent absorbed water and swells, and a large amount of gel precipitates such as calcium carbonate and calcium alumina filled the cracks; the self-healing performance of concrete cracks was the result of both physical and chemical changes.
The damage deterioration law and crack repair mechanism of concrete under different humidity environments were systematically studied by the changes of apparent morphological characteristics, gas permeability, moisture transport and compressive strength, and the incentive mechanism of environmental responsive polymeric repair agents on the self-healing of damaged concrete under different humidity environments was revealed; meanwhile, the microstructure and evolution mechanism of crack self-healing were studied by combining scanning electron microscopy, energy spectrum analysis and X-ray diffraction. The microstructure and evolution mechanism of crack self-healing were also investigated by combining scanning electron microscopy, energy spectrum analysis and X-ray diffraction. The results showed that the natural air and 30% relative humidity curing environment were not conducive to the self-healing behavior of concrete cracks; with the increase of curing humidity, the concrete crack repair rate increased continuously, and the humid environment was favorable for the environmentally responsive polymeric repair agent to give full play to the stimulating effect, promote the crack self-healing characteristics, and prolong the service life; the best repair effect of polymeric repair agent was achieved under the water immersion environment, and the crack healing rate could reach 70.38%, the durability and compressive strength of the repaired concrete were significantly better than those of plain concrete.The main reason for crack healing was that the repair agent absorbed water and swells, and a large amount of gel precipitates such as calcium carbonate and calcium alumina filled the cracks; the self-healing performance of concrete cracks was the result of both physical and chemical changes.
2023, 53(4): 161-172.
doi: 10.13204/j.gyjzG21062705
Abstract:
To promote the durability of glass fiber reinforced ploymer (GFRP) bars, a thin layer of carbon fiber reinforced polymer was wrapped around the internal GFRP bars. The effects of distilled water, strong alkali solution, alkalescent solution, and saline-alkaline solution on the water diffusion and interlaminar shear strength of GFRP and HFRP bars were investigated. It compared with the cement mortar-covered FRP bars in distilled water and seawater. The results showed that in the case of the strong alkaline solution with pH 13.4 and saline-alkaline solution, the saturation water absorption of HFRP was less than that of GFRP. The retention interlaminar shear strength of HFRP bar was larger than GFRP bar, and the carbon fiber coat delayed the degradation of the internal GFRP. In the case of distilled water and alkalescent solution with pH 12.7, the saturation water absorption of HFRP was larger than that of GFRP. The degradation of interlaminar shear strength for HFRP bars was more severe than GFRP bar at 60 ℃. Trends of the variation of interlaminar shear stregnth and the failure modes of the cement mortar-covered FRP bars in distilled water and seawater were similar to the bare FRP bars in distilled water and alkaline solution with pH 12.7. The long-term interlaminar shear strength of GFRP and HFRP bars at 4 ℃, 17 ℃ and 21 ℃ were predicted according to the Arrhenius theory.
To promote the durability of glass fiber reinforced ploymer (GFRP) bars, a thin layer of carbon fiber reinforced polymer was wrapped around the internal GFRP bars. The effects of distilled water, strong alkali solution, alkalescent solution, and saline-alkaline solution on the water diffusion and interlaminar shear strength of GFRP and HFRP bars were investigated. It compared with the cement mortar-covered FRP bars in distilled water and seawater. The results showed that in the case of the strong alkaline solution with pH 13.4 and saline-alkaline solution, the saturation water absorption of HFRP was less than that of GFRP. The retention interlaminar shear strength of HFRP bar was larger than GFRP bar, and the carbon fiber coat delayed the degradation of the internal GFRP. In the case of distilled water and alkalescent solution with pH 12.7, the saturation water absorption of HFRP was larger than that of GFRP. The degradation of interlaminar shear strength for HFRP bars was more severe than GFRP bar at 60 ℃. Trends of the variation of interlaminar shear stregnth and the failure modes of the cement mortar-covered FRP bars in distilled water and seawater were similar to the bare FRP bars in distilled water and alkaline solution with pH 12.7. The long-term interlaminar shear strength of GFRP and HFRP bars at 4 ℃, 17 ℃ and 21 ℃ were predicted according to the Arrhenius theory.
2023, 53(4): 173-179.
doi: 10.13204/j.gyjzG22082212
Abstract:
In order to explore the effect of curing conditions on the mechanical properties of basalt fiber reinforced concrete under impact load, the dynamic uniaxial compression tests of basalt fiber reinforced concrete with different curing ages (1,3,7,14,28 d) and curing relative humidity (35%,55%,75%,95%) were carried out with split Hopkinson compression bar test device (SHPB). The effects of curing age and relative humidity on the average strain rate, peak stress, energy dissipation and fractal dimension of the specimens were analyzed. The results showed that under the same impact load, the average strain rate of specimens would decrease with the increase of curing age and relative humidity. The curing age had an exponential negative correlation with the average strain rate and an exponential positive correlation with the peak stress. The energy time history curve of the specimen under impact load could be divided into three stages. The transmission energy, dissipation energy and crushing energy density increased with the increase of curing age and relative humidity, and the reflection energy decreased with it. The increase of curing age and relative humidity would increase the hydration products of the specimen andenhance the integrity of the specimen. When the curing relative humidity was 95%, compared with the specimens with the curing age of 1 d, the decrease of the fractal dimension of the specimens with the curing age of 3 d, 7 d, 14 d and 28 d was 8.61%, 13.91%, 23.58% and 26.68% respectively. The reduction of curing age and relative humidity would increase the fracture degree of the specimen, and the fractal dimension would increase.
In order to explore the effect of curing conditions on the mechanical properties of basalt fiber reinforced concrete under impact load, the dynamic uniaxial compression tests of basalt fiber reinforced concrete with different curing ages (1,3,7,14,28 d) and curing relative humidity (35%,55%,75%,95%) were carried out with split Hopkinson compression bar test device (SHPB). The effects of curing age and relative humidity on the average strain rate, peak stress, energy dissipation and fractal dimension of the specimens were analyzed. The results showed that under the same impact load, the average strain rate of specimens would decrease with the increase of curing age and relative humidity. The curing age had an exponential negative correlation with the average strain rate and an exponential positive correlation with the peak stress. The energy time history curve of the specimen under impact load could be divided into three stages. The transmission energy, dissipation energy and crushing energy density increased with the increase of curing age and relative humidity, and the reflection energy decreased with it. The increase of curing age and relative humidity would increase the hydration products of the specimen andenhance the integrity of the specimen. When the curing relative humidity was 95%, compared with the specimens with the curing age of 1 d, the decrease of the fractal dimension of the specimens with the curing age of 3 d, 7 d, 14 d and 28 d was 8.61%, 13.91%, 23.58% and 26.68% respectively. The reduction of curing age and relative humidity would increase the fracture degree of the specimen, and the fractal dimension would increase.
2023, 53(4): 180-189.
doi: 10.13204/j.gyjzG23012403
Abstract:
Supported by primary theoretical developments that all things generate numbers and numbers generate all things, digital twin combines multi-level spatio-temporal development of cities, buildings, and individuals into an iterative coupled combination of urban renewal scenarios where virtual and real are superimposed. This paper focused on new development concept of integrated application between key technologies of digital twin and urban renewal industries. In addition, new development paradigms of digital twin cities, digital twin buildings, and human digital twin were explained particularly. Furthermore, this paper provided in-depth analysis of digital twin technology system in new development stage and typical application scenarios of urban physical examination, prefabricated buildings, and individual spatiotemporal indexes. Thus, this paper carried out research work on digital twin theoretical architecture, technical application, and scene construction around urban renewal, aiming to contribute to this growing area of research by taking digital twin technology for the overall driving core of digital transformation, and leading the orderly advancement of urban renewal through differentiated innovation at circled levels.
Supported by primary theoretical developments that all things generate numbers and numbers generate all things, digital twin combines multi-level spatio-temporal development of cities, buildings, and individuals into an iterative coupled combination of urban renewal scenarios where virtual and real are superimposed. This paper focused on new development concept of integrated application between key technologies of digital twin and urban renewal industries. In addition, new development paradigms of digital twin cities, digital twin buildings, and human digital twin were explained particularly. Furthermore, this paper provided in-depth analysis of digital twin technology system in new development stage and typical application scenarios of urban physical examination, prefabricated buildings, and individual spatiotemporal indexes. Thus, this paper carried out research work on digital twin theoretical architecture, technical application, and scene construction around urban renewal, aiming to contribute to this growing area of research by taking digital twin technology for the overall driving core of digital transformation, and leading the orderly advancement of urban renewal through differentiated innovation at circled levels.
2023, 53(4): 190-198.
doi: 10.13204/j.gyjzG22042612
Abstract:
The potential construction advantages of 3D printing technology are of great significance to promote the building industrialization, and its application to raw soil construction is one of the focuses of attention and research at home and abroad. Firstly, the preparation technology of 3D printing raw soil was reviewed from the aspects of the composition of 3D printing raw materials, the rheology of raw soil to meet the requirements of 3D printing, and the shrinkage and cracking caused by drying of raw soil. The extrudability and maximum height of raw soil from the printing nozzle were summarized. The influence of process parameters such as nozzle shape and size, printing speed and path on the molding of 3D printing raw soil was analyzed. This paper mainly summarized the research status of compressive strength and interlayer bond strength of 3D printed raw soil after hardening, and finally introduced the problems faced by 3D printing raw soil construction technology and the prospect of the future, which could provide a reference for the research and development of 3D printing raw soil construction technology.
The potential construction advantages of 3D printing technology are of great significance to promote the building industrialization, and its application to raw soil construction is one of the focuses of attention and research at home and abroad. Firstly, the preparation technology of 3D printing raw soil was reviewed from the aspects of the composition of 3D printing raw materials, the rheology of raw soil to meet the requirements of 3D printing, and the shrinkage and cracking caused by drying of raw soil. The extrudability and maximum height of raw soil from the printing nozzle were summarized. The influence of process parameters such as nozzle shape and size, printing speed and path on the molding of 3D printing raw soil was analyzed. This paper mainly summarized the research status of compressive strength and interlayer bond strength of 3D printed raw soil after hardening, and finally introduced the problems faced by 3D printing raw soil construction technology and the prospect of the future, which could provide a reference for the research and development of 3D printing raw soil construction technology.
2023, 53(4): 199-203.
doi: 10.13204/j.gyjzG21123004
Abstract:
With the depletion of mineral resources and industrial upgrading and transformation, mining derelict lands have emerged in large numbers and gradually come into public view. In order to make full use of the derelict lands, turn waste into treasure, and promote urban ecological restoration and spatial repair, the adaptive construction of Qiseshan Quarry Garden and its visitor center project were explored based on site conditions, which was expected to provide reference to research or design in related fields.
With the depletion of mineral resources and industrial upgrading and transformation, mining derelict lands have emerged in large numbers and gradually come into public view. In order to make full use of the derelict lands, turn waste into treasure, and promote urban ecological restoration and spatial repair, the adaptive construction of Qiseshan Quarry Garden and its visitor center project were explored based on site conditions, which was expected to provide reference to research or design in related fields.
