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2025 Vol. 55, No. 2
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2025, 55(2): 1-9.
doi: 10.3724/j.gyjzG24083101
Abstract:
To enrich the fundamental data on the physical and mechanical properties of bamboo scrimber and to promote its application in building structures, five densities (0.8, 0.9, 1.0, 1.1, 1.2 g/cm3) and two kinds of assembly methods (longitudinal, vertical and horizontal) of Bambusa emeiensis bamboo scrimber were prepared.According to the standards Structural Bamboo Scrimber (LY/T 3194—2020) and Bamboo Scrimber (GB/T 40247—2021), the study evaluated 13 properties, including density, water resistance, bending resistance, compressive strength, tensile strength, and shear resistance. The results revealed that the measured density varied from the set density in different areas of the bamboo scrimber board. The density deviation of the longitudinal plates was from -3.95% to 5.89%, and the density deviation of the vertical and horizontal plates was from -5.80% to 6.22%. As the density increased, the overall physical and mechanical properties of longitudinal plates improved, although the strength of vertical and horizontal plates did not vary significantly with density. For the longitudinal plates, the water absorption width expansion rate ranged from 0.69% to 2.73%, and the water absorption thickness expansion ratio ranged from 3.27% to 6.56%. The bending strength was between 194.5 MPa and 228.2 MPa, the bending modulus of elasticity ranged from 19.03 GPa to 28.90 GPa, and the horizontal shear strength ranged from 10.8 MPa to 18.5 MPa. The mechanical strength of the vertical and horizontal plates was generally lower than that of the longitudinal plates, while transverse compressive strength, shearing strength parallel to grain and widths welling were higher than those of the longitudinal plates. Based on the measured physical and mechanical strength data, it was recommended to use bamboo scrimber with a density greater than 0.95 g/cm3 to achieve better strength stability in practical applications.
To enrich the fundamental data on the physical and mechanical properties of bamboo scrimber and to promote its application in building structures, five densities (0.8, 0.9, 1.0, 1.1, 1.2 g/cm3) and two kinds of assembly methods (longitudinal, vertical and horizontal) of Bambusa emeiensis bamboo scrimber were prepared.According to the standards Structural Bamboo Scrimber (LY/T 3194—2020) and Bamboo Scrimber (GB/T 40247—2021), the study evaluated 13 properties, including density, water resistance, bending resistance, compressive strength, tensile strength, and shear resistance. The results revealed that the measured density varied from the set density in different areas of the bamboo scrimber board. The density deviation of the longitudinal plates was from -3.95% to 5.89%, and the density deviation of the vertical and horizontal plates was from -5.80% to 6.22%. As the density increased, the overall physical and mechanical properties of longitudinal plates improved, although the strength of vertical and horizontal plates did not vary significantly with density. For the longitudinal plates, the water absorption width expansion rate ranged from 0.69% to 2.73%, and the water absorption thickness expansion ratio ranged from 3.27% to 6.56%. The bending strength was between 194.5 MPa and 228.2 MPa, the bending modulus of elasticity ranged from 19.03 GPa to 28.90 GPa, and the horizontal shear strength ranged from 10.8 MPa to 18.5 MPa. The mechanical strength of the vertical and horizontal plates was generally lower than that of the longitudinal plates, while transverse compressive strength, shearing strength parallel to grain and widths welling were higher than those of the longitudinal plates. Based on the measured physical and mechanical strength data, it was recommended to use bamboo scrimber with a density greater than 0.95 g/cm3 to achieve better strength stability in practical applications.
2025, 55(2): 10-19.
doi: 10.3724/j.gyjzG24083104
Abstract:
Moso bamboo was used as the raw material to produce bamboo scrimber with five different densities and two assembly methods. The physical and mechanical properties of the bamboo scrimber were measured and analyzed to provide data support for the application of bamboo scrimber in building structures. The results showed that bamboo scrimber exhibited excellent water resistance. Overall, the physical and mechanical properties of bamboo scrimber were enhanced with the increase of density. The bending strength, bending modulus, compressive strength parallel to the grain, tensile strength parallel to the grain, and horizontal shear strength were all higher in the longitudinal board compared to the vertical and horizontal board. However, the vertical and horizontal board showed superior shear strength parallel to the grain, total transverse compressive strength, and local transverse compressive strength compared to the longitudinal board. The optimal assembly method and densities should be selected based on specific production requirements.
Moso bamboo was used as the raw material to produce bamboo scrimber with five different densities and two assembly methods. The physical and mechanical properties of the bamboo scrimber were measured and analyzed to provide data support for the application of bamboo scrimber in building structures. The results showed that bamboo scrimber exhibited excellent water resistance. Overall, the physical and mechanical properties of bamboo scrimber were enhanced with the increase of density. The bending strength, bending modulus, compressive strength parallel to the grain, tensile strength parallel to the grain, and horizontal shear strength were all higher in the longitudinal board compared to the vertical and horizontal board. However, the vertical and horizontal board showed superior shear strength parallel to the grain, total transverse compressive strength, and local transverse compressive strength compared to the longitudinal board. The optimal assembly method and densities should be selected based on specific production requirements.
2025, 55(2): 20-30.
doi: 10.3724/j.gyjzG24102102
Abstract:
Investigating the population distribution of the mechanical parameters of bamboo scrimber, establishing regression models between the compressive strength parallel to grain and other mechanical parameters, and then providing a basis for the engineering application of bamboo scrimber. Data from 2 925 bamboo scrimber material tests was collected. Then the consistency of the sample data for each mechanical parameter of bamboo scrimber with normal, lognormal, Gumbel, Weibull, and Cauchy distribution was inferred using the Kolmogorov-Smirnov test. Finally, based on the optimal population distribution of each mechanical parameter, the regression models of the compressive strength of bamboo scrimber compressive strength parallel to grain with other mechanical parameters were established. The results showed that the mechanical parameters of bamboo scrimber obeyed the skewed distribution; the linear function and power function could fit the relations between the compressive strength parallel to grain and other mechanical parameters of bamboo scrimber well.
Investigating the population distribution of the mechanical parameters of bamboo scrimber, establishing regression models between the compressive strength parallel to grain and other mechanical parameters, and then providing a basis for the engineering application of bamboo scrimber. Data from 2 925 bamboo scrimber material tests was collected. Then the consistency of the sample data for each mechanical parameter of bamboo scrimber with normal, lognormal, Gumbel, Weibull, and Cauchy distribution was inferred using the Kolmogorov-Smirnov test. Finally, based on the optimal population distribution of each mechanical parameter, the regression models of the compressive strength of bamboo scrimber compressive strength parallel to grain with other mechanical parameters were established. The results showed that the mechanical parameters of bamboo scrimber obeyed the skewed distribution; the linear function and power function could fit the relations between the compressive strength parallel to grain and other mechanical parameters of bamboo scrimber well.
2025, 55(2): 31-43.
doi: 10.3724/j.gyjzG24102104
Abstract:
Based on existing experimental investigations of the dowel-bearing properties of two typical bamboo species bambusa eiemeiensis and phyllostachys edulis, supplemented with additional tests to verify influencing factors including bamboo species, load-to-fiber direction angle (LFD), density, and dowel diameter. A comparative analysis was conducted on the mechanical properties and applicability of calculation methods for both bamboo scrimber types. The results indicated: at LFD approaching 0°, bamboo scrimber primarily failed through direct shear failure of fiber-adhesive layers, transitioning to fiber bending-induced shear failure of adhesive layers when LFD approached 90°. Crack propagation intensified with increasing LFD, with phyllostachys edulis-based specimens exhibiting more pronounced failure. At LFD 45°, cracks demonstrated stronger penetration. Increased dowel diameter exacerbated bamboo scrimber failure, particularly in phyllostachys edulis-based materials. Low-density specimens were prone to premature failure. Bambusa emeiensis-based bamboo scrimber exhibited higher stiffness and strength than phyllostachys edulis-based counterparts. Both bamboo scrimbers showed decreasing dowel-bearing stiffness with increasing LFD, though bambusa emeiensis-based specimens exhibited stiffness recovery at LFD >75°. The strength reached its minimum at LFD 45° before rebounding. Increased dowel diameter enhanced stiffness but reduced strength in bambusa emeiensis-based materials, while phyllostachys edulis-based materials increased at first and then decreased in both stiffness and strength. Based on the above results, a calculation model for the dowel-bearing performance of both bamboo scrimber types with different LFDs and dowel diameters were established ultimately.
Based on existing experimental investigations of the dowel-bearing properties of two typical bamboo species bambusa eiemeiensis and phyllostachys edulis, supplemented with additional tests to verify influencing factors including bamboo species, load-to-fiber direction angle (LFD), density, and dowel diameter. A comparative analysis was conducted on the mechanical properties and applicability of calculation methods for both bamboo scrimber types. The results indicated: at LFD approaching 0°, bamboo scrimber primarily failed through direct shear failure of fiber-adhesive layers, transitioning to fiber bending-induced shear failure of adhesive layers when LFD approached 90°. Crack propagation intensified with increasing LFD, with phyllostachys edulis-based specimens exhibiting more pronounced failure. At LFD 45°, cracks demonstrated stronger penetration. Increased dowel diameter exacerbated bamboo scrimber failure, particularly in phyllostachys edulis-based materials. Low-density specimens were prone to premature failure. Bambusa emeiensis-based bamboo scrimber exhibited higher stiffness and strength than phyllostachys edulis-based counterparts. Both bamboo scrimbers showed decreasing dowel-bearing stiffness with increasing LFD, though bambusa emeiensis-based specimens exhibited stiffness recovery at LFD >75°. The strength reached its minimum at LFD 45° before rebounding. Increased dowel diameter enhanced stiffness but reduced strength in bambusa emeiensis-based materials, while phyllostachys edulis-based materials increased at first and then decreased in both stiffness and strength. Based on the above results, a calculation model for the dowel-bearing performance of both bamboo scrimber types with different LFDs and dowel diameters were established ultimately.
2025, 55(2): 44-51.
doi: 10.3724/j.gyjzG24102205
Abstract:
In order to investigate the seismic performance of two typical types of bamboo scrimber beam-column joints, namely the mortise-tenon joint and the bolted bamboo scrimber (BS)-steel-bamboo scrimber (BS) joint, two joint specimens were designed, fabricated and conducted on the quasi-static loading. The failure mode, moment-rotation curves, bearing capacity, strength and stiffness degradation, and energy dissipation capacity of the two types of joints were compared and analyzed. The results indicated that the failure of the mortise-tenon joint was mainly caused by the extraction of tenon, while the failure of the bolted BS-steel-BS joint was mainly caused by the extraction of beam end, the formation of through transverse cracks in the panel zone on the column, and the formation of bending plastic hinge by bolts. The hysteretic curves of both types of joints showed an inverse "Z" shape, but the slip of the mortise-tenon joint was shorter and the "pinching" effect was milder. The bolted BS-steel-BS joint had superior bearing capacity and less strength degradation. At the beginning of loading, the mortise-tenon joint showed higher stiffness but lower energy dissipation capacity. However, in the middle later stages of loading, the bolted BS-steel-BS joint had higher stiffness but lower energy dissipation capacity. The two types of joints have their own advantages, and a new type of bamboo scrimber beam-column joint with better overall performance can be proposed by comprehensively considering the advantages of both types of joints.
In order to investigate the seismic performance of two typical types of bamboo scrimber beam-column joints, namely the mortise-tenon joint and the bolted bamboo scrimber (BS)-steel-bamboo scrimber (BS) joint, two joint specimens were designed, fabricated and conducted on the quasi-static loading. The failure mode, moment-rotation curves, bearing capacity, strength and stiffness degradation, and energy dissipation capacity of the two types of joints were compared and analyzed. The results indicated that the failure of the mortise-tenon joint was mainly caused by the extraction of tenon, while the failure of the bolted BS-steel-BS joint was mainly caused by the extraction of beam end, the formation of through transverse cracks in the panel zone on the column, and the formation of bending plastic hinge by bolts. The hysteretic curves of both types of joints showed an inverse "Z" shape, but the slip of the mortise-tenon joint was shorter and the "pinching" effect was milder. The bolted BS-steel-BS joint had superior bearing capacity and less strength degradation. At the beginning of loading, the mortise-tenon joint showed higher stiffness but lower energy dissipation capacity. However, in the middle later stages of loading, the bolted BS-steel-BS joint had higher stiffness but lower energy dissipation capacity. The two types of joints have their own advantages, and a new type of bamboo scrimber beam-column joint with better overall performance can be proposed by comprehensively considering the advantages of both types of joints.
2025, 55(2): 52-59.
doi: 10.3724/j.gyjzG24111103
Abstract:
Bamboo scrimber has excellent mechanical properties and is a green building material that meets the requirements of sustainable development. In order to further improve the basic theoretical research on bamboo scrimber members, four-point loading static bending tests were carried out on bamboo scrimber solid web beams and trusses to investigate the effects of horizontal and vertical gluing in the direction of the grain on bamboo scrimber solid web beams, and the effects of tongue-and-groove and plywood connections on the mechanical properties of bamboo scrimber trusses. The results showed that the damage of bamboo scrimber solid web beams was caused by cracking of finger joints, and the finger joints were not easy to crack when glued horizontally in the vertical direction of the grain, the tenon joint trusses showed the strength damage mode of lower chord joint cracking, and the plywood joint trusses were out-of-plane instability; the stiffnesses of the two types of solid web beams were basically the same, but the solid web beams glued vertically in the direction of the grain were of higher bearing capacity, and the strength of the materials were more fully utilised; the two types of trusses had basically equal bearing capacity, but the stiffness of tongue-and-groove jointed trusses was higher. Based on the results of the study, it was recommended that the solid web beams showed be glued horizontally in the vertical direction of smooth grain and the truss rods should be connected by tongue-and-groove type in engineering practice.
Bamboo scrimber has excellent mechanical properties and is a green building material that meets the requirements of sustainable development. In order to further improve the basic theoretical research on bamboo scrimber members, four-point loading static bending tests were carried out on bamboo scrimber solid web beams and trusses to investigate the effects of horizontal and vertical gluing in the direction of the grain on bamboo scrimber solid web beams, and the effects of tongue-and-groove and plywood connections on the mechanical properties of bamboo scrimber trusses. The results showed that the damage of bamboo scrimber solid web beams was caused by cracking of finger joints, and the finger joints were not easy to crack when glued horizontally in the vertical direction of the grain, the tenon joint trusses showed the strength damage mode of lower chord joint cracking, and the plywood joint trusses were out-of-plane instability; the stiffnesses of the two types of solid web beams were basically the same, but the solid web beams glued vertically in the direction of the grain were of higher bearing capacity, and the strength of the materials were more fully utilised; the two types of trusses had basically equal bearing capacity, but the stiffness of tongue-and-groove jointed trusses was higher. Based on the results of the study, it was recommended that the solid web beams showed be glued horizontally in the vertical direction of smooth grain and the truss rods should be connected by tongue-and-groove type in engineering practice.
2025, 55(2): 60-72.
doi: 10.3724/j.gyjzG24030514
Abstract:
With the deepening of globalisation, global cities are facing increasingly fierce competitions such as culture, talents and capital, and the level of urban governance has become the key to attracting resources. Urban regeneration is an important opportunity to improve urban development and governance level in China, among which the historical industrial district is a representative of the importance, complexity and urgency, and the multiple-stakeholder collaboration is a key approach to realise the public interest. This paper focusesd on the regeneration mechanisms, influencing factors and improving strategies for realising public interests in urban regeneration of historical industrial districts with the participation of multi-stakeholders. Taking the two rounds of urban regeneration of Red Town site in Shanghai and EC1 in Łódź, Poland as examples, it established the framework of "Participating Actors-Policy System-Regeneration Effect" to sort out the mechanism of multi-actor collaboration and the policy system; evaluate the effectiveness of regeneration was evaluated from the perspective of public interest. The framework of "Participating Actors-Renewal System-Renewal Effect" was established to sort out the mechanism of multi-actor collaboration and policy system; the effectiveness of its comprehensive dimensions of regeneration was evaluated from the perspective of public interest, exploring the factors influencing the spatial governance mechanism of urban regeneration on the realisation of public interest in industrial historical districts and the strategies, and drawing on the experience from international cases, in order to contribute to the realisation of high-quality and sustainable development oriented to public interest in Chinese cities.
With the deepening of globalisation, global cities are facing increasingly fierce competitions such as culture, talents and capital, and the level of urban governance has become the key to attracting resources. Urban regeneration is an important opportunity to improve urban development and governance level in China, among which the historical industrial district is a representative of the importance, complexity and urgency, and the multiple-stakeholder collaboration is a key approach to realise the public interest. This paper focusesd on the regeneration mechanisms, influencing factors and improving strategies for realising public interests in urban regeneration of historical industrial districts with the participation of multi-stakeholders. Taking the two rounds of urban regeneration of Red Town site in Shanghai and EC1 in Łódź, Poland as examples, it established the framework of "Participating Actors-Policy System-Regeneration Effect" to sort out the mechanism of multi-actor collaboration and the policy system; evaluate the effectiveness of regeneration was evaluated from the perspective of public interest. The framework of "Participating Actors-Renewal System-Renewal Effect" was established to sort out the mechanism of multi-actor collaboration and policy system; the effectiveness of its comprehensive dimensions of regeneration was evaluated from the perspective of public interest, exploring the factors influencing the spatial governance mechanism of urban regeneration on the realisation of public interest in industrial historical districts and the strategies, and drawing on the experience from international cases, in order to contribute to the realisation of high-quality and sustainable development oriented to public interest in Chinese cities.
2025, 55(2): 73-81.
doi: 10.3724/j.gyjzG23032006
Abstract:
The airport hub energized cities which is becoming more and more prominent. Also, the "integration of airport, industry and city" has become a new engine to enhance the comprehensive capabilities of the airport area and a new mode of urban development. The airport portal area plays a dual role of continuing the airport functions and carrying the gathering of urban activities. However, the space in front of most large airports in China has failed to effectively play the role of association with urban functions. Based on this problem, the paper proposed corresponding spatial planning strategies with city catalytic and space syntax, emphasized the role of the transportation hub connecting the inside and outside of the airport area, and took Xi’an T5 portal business district as an example to provide an important reference for the construction of a modern airport portal area.
The airport hub energized cities which is becoming more and more prominent. Also, the "integration of airport, industry and city" has become a new engine to enhance the comprehensive capabilities of the airport area and a new mode of urban development. The airport portal area plays a dual role of continuing the airport functions and carrying the gathering of urban activities. However, the space in front of most large airports in China has failed to effectively play the role of association with urban functions. Based on this problem, the paper proposed corresponding spatial planning strategies with city catalytic and space syntax, emphasized the role of the transportation hub connecting the inside and outside of the airport area, and took Xi’an T5 portal business district as an example to provide an important reference for the construction of a modern airport portal area.
2025, 55(2): 82-91.
doi: 10.3724/j.gyjzG24101702
Abstract:
Exploring the color characteristics of spatial buildings in the streets and alleys of Huizhou, aiming to quantify subjective color experiences and transform them into objective data for the precise analysis of their unique color composition and distribution patterns.Taking the streets and alleys of Hongcun, Huizhou, as a case study, the research analyzed the color values and spatial distribution characteristics of building facades under static visual perception through color histograms and channel visualization. Under dynamic visual perception, the study examined the changes in color attributes of continuous facades and introduced the concepts of color chroma and color similarity to explore the color characteristics in dynamic perception. The results showed that: 1) In static perception, Huizhou street and alley buildings predominantly featured warm tones and low chroma, with brightness distribution enhancing the color hierarchy. 2) The hue was mainly distributed within the range of 0°-60°, the chroma within the range of 0-33, both presenting continuous distribution; the brightness showed continuity across all intervals, with the medium brightness range being the most prominent, followed by high brightness, and then low brightness. 3) Most facade color harmony values remained stable within the range of 0.6-0.9, indicating a high level of harmony, though the harmony between adjacent facades fluctuate more randomly. Color similarity primarily concentrated within the range of 0.7-0.9, exhibiting stable fluctuations. Based on these quantitative results, the study proposed a color control strategy for Huizhou architecture, providing scientific evidence for the protection of traditional architecture and modern design.
Exploring the color characteristics of spatial buildings in the streets and alleys of Huizhou, aiming to quantify subjective color experiences and transform them into objective data for the precise analysis of their unique color composition and distribution patterns.Taking the streets and alleys of Hongcun, Huizhou, as a case study, the research analyzed the color values and spatial distribution characteristics of building facades under static visual perception through color histograms and channel visualization. Under dynamic visual perception, the study examined the changes in color attributes of continuous facades and introduced the concepts of color chroma and color similarity to explore the color characteristics in dynamic perception. The results showed that: 1) In static perception, Huizhou street and alley buildings predominantly featured warm tones and low chroma, with brightness distribution enhancing the color hierarchy. 2) The hue was mainly distributed within the range of 0°-60°, the chroma within the range of 0-33, both presenting continuous distribution; the brightness showed continuity across all intervals, with the medium brightness range being the most prominent, followed by high brightness, and then low brightness. 3) Most facade color harmony values remained stable within the range of 0.6-0.9, indicating a high level of harmony, though the harmony between adjacent facades fluctuate more randomly. Color similarity primarily concentrated within the range of 0.7-0.9, exhibiting stable fluctuations. Based on these quantitative results, the study proposed a color control strategy for Huizhou architecture, providing scientific evidence for the protection of traditional architecture and modern design.
2025, 55(2): 92-100.
doi: 10.3724/j.gyjzG23102907
Abstract:
In response to the problems of low efficiency, low accuracy, and lack of scientific evaluation system in current evaluation methods, an evaluation method combining BP neural network and Analytic Hierarchy Process was designed. In the specific evaluation process, it was achieved by constructing an evaluation system, calculating indicator weights, creating a network structure, selecting training samples, and verifying the model. Firstly,the paper analyzed the landscape design under the concept of low impact development, identified existing problems, and constructed an evaluation system. Then, Analytic Hierarchy Process was used to construct a hierarchical model and determine the weights of each indicator. Then, construct a BP neural network model was constracted and trained with sample data. Finally, select 10 samples were selected from 100 samples for simulation testing, and applied them to actual cases. The results show that this method had higher evaluation accuracy compared to traditional single Analytic Hierarchy Process and BP neural network evaluation models. In case applications, the test results were consistent with expert evaluation results, making the evaluation effect of landscape design under the low impact development concept ideal. It can effectively adapt to the complexity and diversity of modern landscape design and provide scientific reference opinions for relevant practitioners.
In response to the problems of low efficiency, low accuracy, and lack of scientific evaluation system in current evaluation methods, an evaluation method combining BP neural network and Analytic Hierarchy Process was designed. In the specific evaluation process, it was achieved by constructing an evaluation system, calculating indicator weights, creating a network structure, selecting training samples, and verifying the model. Firstly,the paper analyzed the landscape design under the concept of low impact development, identified existing problems, and constructed an evaluation system. Then, Analytic Hierarchy Process was used to construct a hierarchical model and determine the weights of each indicator. Then, construct a BP neural network model was constracted and trained with sample data. Finally, select 10 samples were selected from 100 samples for simulation testing, and applied them to actual cases. The results show that this method had higher evaluation accuracy compared to traditional single Analytic Hierarchy Process and BP neural network evaluation models. In case applications, the test results were consistent with expert evaluation results, making the evaluation effect of landscape design under the low impact development concept ideal. It can effectively adapt to the complexity and diversity of modern landscape design and provide scientific reference opinions for relevant practitioners.
2025, 55(2): 101-110.
doi: 10.3724/j.gyjzG22092410
Abstract:
The numerical analysis model of mortise-tenon joint shear walls was established by using the finite element analysis software ABAQUS. The influence of different tenon structures on the mechanical properties of mortise-tenon joint shear walls was studied, and the comparative analysis was carried out from the aspects of shear wall mechanical properties, overall failure mode and local failure mode. The results showed that different contact models were established according to the force conditions of the new and old concrete interfaces, which could accurately simulate the interaction between the interfaces in the mortise-tenon joint shear wall. Setting mortise-tenon holes in the composite structure could improve the deformation capacity before the peak value of the mortise-tenon joint shear walls, and the bearing capacity and ductility decreased. The crack development at the bottom of the tensile side of the mortise-tenon shear wall with combined mortise-tenon structure increased, and the crack development at the root of the transverse bulge of the mortise-tenon plate and the central through hole was significantly reduced. In the limit state, the setting of composite mortise-tenon joint could significantly reduce the local compressive damage at the transverse bulge position of the mortise-tenon joint shear wall.
The numerical analysis model of mortise-tenon joint shear walls was established by using the finite element analysis software ABAQUS. The influence of different tenon structures on the mechanical properties of mortise-tenon joint shear walls was studied, and the comparative analysis was carried out from the aspects of shear wall mechanical properties, overall failure mode and local failure mode. The results showed that different contact models were established according to the force conditions of the new and old concrete interfaces, which could accurately simulate the interaction between the interfaces in the mortise-tenon joint shear wall. Setting mortise-tenon holes in the composite structure could improve the deformation capacity before the peak value of the mortise-tenon joint shear walls, and the bearing capacity and ductility decreased. The crack development at the bottom of the tensile side of the mortise-tenon shear wall with combined mortise-tenon structure increased, and the crack development at the root of the transverse bulge of the mortise-tenon plate and the central through hole was significantly reduced. In the limit state, the setting of composite mortise-tenon joint could significantly reduce the local compressive damage at the transverse bulge position of the mortise-tenon joint shear wall.
Research on the Wind-Induced Interference Effect on New and Existing Cooling Towers of the Same Size
2025, 55(2): 111-120.
doi: 10.3724/j.gyjzG24042815
Abstract:
The extension of the power plant will generate the wind-induced interference effect on the new and existing cooling towers, which is one of the important reasons of the failure and collapse of the cooling towers caused by wind. The current code and existing research completely ignore the extreme value of the wind load of the cooling tower in such cases. Taking the new and existing cooling towers of the same size in a power plant in Qinzhou, Guangxi Province as the object, on the basis of the existing tandem two-tower combination, a total of 240 working conditions of the three-tower and four-tower combination of the new cooling tower were considered. The wind tunnel test for rigid body was used to analyze the average wind pressures and pulsation distribution characteristics of these towers. Then based on the overall coefficient of resistance, the interference effects under different tower group combinations were quantitatively compared and analyzed, the static and extreme interference factors of new and existing cooling towers were proposed, the influence mechanism of new towers on the average and fluctuating wind pressure distribution on the surface of existing cooling towers was discussed, and the model of extreme wind pressures for new and existing cooling tower groups was established. It was found that the interference effect of the new cooling towers (groups) of the same size on the existing cooling tower groups was significant, especially when the towers were located along the wind direction. Also the "sandwich effect" formed by the disturbed towers and the disturbing building enhanced the interference effect most significantly, where the maximum extreme interference factor of the existing towers was increased by 7%, and the static interference factor was increased by 8.7% under the most unfavorable working condition of the three-tower combination.
The extension of the power plant will generate the wind-induced interference effect on the new and existing cooling towers, which is one of the important reasons of the failure and collapse of the cooling towers caused by wind. The current code and existing research completely ignore the extreme value of the wind load of the cooling tower in such cases. Taking the new and existing cooling towers of the same size in a power plant in Qinzhou, Guangxi Province as the object, on the basis of the existing tandem two-tower combination, a total of 240 working conditions of the three-tower and four-tower combination of the new cooling tower were considered. The wind tunnel test for rigid body was used to analyze the average wind pressures and pulsation distribution characteristics of these towers. Then based on the overall coefficient of resistance, the interference effects under different tower group combinations were quantitatively compared and analyzed, the static and extreme interference factors of new and existing cooling towers were proposed, the influence mechanism of new towers on the average and fluctuating wind pressure distribution on the surface of existing cooling towers was discussed, and the model of extreme wind pressures for new and existing cooling tower groups was established. It was found that the interference effect of the new cooling towers (groups) of the same size on the existing cooling tower groups was significant, especially when the towers were located along the wind direction. Also the "sandwich effect" formed by the disturbed towers and the disturbing building enhanced the interference effect most significantly, where the maximum extreme interference factor of the existing towers was increased by 7%, and the static interference factor was increased by 8.7% under the most unfavorable working condition of the three-tower combination.
2025, 55(2): 121-129.
doi: 10.3724/j.gyjzG22051602
Abstract:
In order to analyze the influence of the arrangement of diaphragms on the bridge, a solid model was established by using the finite element software. According to the parameters of the bridge itself, such as warping deformation, distortion stress and torsional stress, the torsion and distortion effects of the corrugated steel web bridges with different spacings and numbers of diaphragm plates were analyzed in detail by changing the form of loads. The results showed that the roof was subjected to the maximum stress under the eccentric concentrated load, and the maximum torsional stress was only 40% of the maximum distortion stress. The anti-distortion capacity of a section was mainly determined by the distance between the two nearest diaphragms. The location of the diaphragm was not proportional to the torsion resistance of the section. Compared with the distortion load, the stress mutation at the diaphragm was more obvious under torsional loads. Compared with the longitudinal warping displacement, the setting of diaphragms had more significant effect on the transverse warping displacement of the bridge. The installation of diaphragm in the middle span had great influence on the anti-distortion capability of the bridge.
In order to analyze the influence of the arrangement of diaphragms on the bridge, a solid model was established by using the finite element software. According to the parameters of the bridge itself, such as warping deformation, distortion stress and torsional stress, the torsion and distortion effects of the corrugated steel web bridges with different spacings and numbers of diaphragm plates were analyzed in detail by changing the form of loads. The results showed that the roof was subjected to the maximum stress under the eccentric concentrated load, and the maximum torsional stress was only 40% of the maximum distortion stress. The anti-distortion capacity of a section was mainly determined by the distance between the two nearest diaphragms. The location of the diaphragm was not proportional to the torsion resistance of the section. Compared with the distortion load, the stress mutation at the diaphragm was more obvious under torsional loads. Compared with the longitudinal warping displacement, the setting of diaphragms had more significant effect on the transverse warping displacement of the bridge. The installation of diaphragm in the middle span had great influence on the anti-distortion capability of the bridge.
2025, 55(2): 130-137.
doi: 10.3724/j.gyjzG22071402
Abstract:
In order to study the in-plane bending performance of doubler-plate reinforced (DPR) or vertical inner plate reinforced (IPR) square tubular T-joints, experimental tests and numerical simulations were carried out on unreinforced and DPR or IPR joints with the brace to chord width ratio of 0.8, as well as an equal width joint for comparison. The failure modes, moment-strain curves and moment-rotation curves of the specimens were analyzed. The finite element models of the joints with different β(0.4,0.6 and 0.8) were established and the bearing mechanism of the reinforced joints was discussed. The experimental results showed the flexural capacity of DPR joints and IPR joints was significantly improved comparing to the unreinforced ones, the flexural strength and the initial stiffness impoved by 71% and 123%, compared with the unreinforced joints. The vertical inner plate was effective to protect the weld between the chord and the brace, and transfered the failure from the cracks of the weld to the yielding of the brace. The doubler-plate could protect the chord flange and change the failure mode from chord flange yield to doubler-plate yield. The reinforced joints had better ductility than the equal width joint, yet demonstrated a lower flexural strength and stiffness. Further mechanism analysis from the finite element results indicated that the doubler-plate improved the flexural strength of the joint by increasing the local stiffness of the chord flange on the compressive side. The vertical inner plate improved the flexural stiffness at the intersection zone and protected the welds between the chord and the brace, thus enhancing the flexural strength of the joint.
In order to study the in-plane bending performance of doubler-plate reinforced (DPR) or vertical inner plate reinforced (IPR) square tubular T-joints, experimental tests and numerical simulations were carried out on unreinforced and DPR or IPR joints with the brace to chord width ratio of 0.8, as well as an equal width joint for comparison. The failure modes, moment-strain curves and moment-rotation curves of the specimens were analyzed. The finite element models of the joints with different β(0.4,0.6 and 0.8) were established and the bearing mechanism of the reinforced joints was discussed. The experimental results showed the flexural capacity of DPR joints and IPR joints was significantly improved comparing to the unreinforced ones, the flexural strength and the initial stiffness impoved by 71% and 123%, compared with the unreinforced joints. The vertical inner plate was effective to protect the weld between the chord and the brace, and transfered the failure from the cracks of the weld to the yielding of the brace. The doubler-plate could protect the chord flange and change the failure mode from chord flange yield to doubler-plate yield. The reinforced joints had better ductility than the equal width joint, yet demonstrated a lower flexural strength and stiffness. Further mechanism analysis from the finite element results indicated that the doubler-plate improved the flexural strength of the joint by increasing the local stiffness of the chord flange on the compressive side. The vertical inner plate improved the flexural stiffness at the intersection zone and protected the welds between the chord and the brace, thus enhancing the flexural strength of the joint.
2025, 55(2): 138-145.
doi: 10.3724/j.gyjzG23070607
Abstract:
In order to discuss the accuracy of the shape factor of the three-parameter power function moment-rotation curves of semi-rigid steel beam-column joints, the finite element software ANSYS was used to simulate and analyze. The finite element solid model and the three-parameter power function model based on the component method were established respectively for the typical semi-rigid joints of the extended end plate, which were verified with the test results. Based on the Weber distribution, the practical calculation formula of the shape factor of the semi-rigid connection of the extended end plate was fitted through the finite element solid model and the three-parameter power function model based on the component method. The results showed that the formula for calculating the shape factor of semi-rigid connections with extended end plates based on Weber distribution was more accurate than the existing formula; by giving COMBIN39 element a simplified finite element model of bending moment-rotation curves obtained from the three parameter power function based on the comporent method, the design could not only accurately simulate the mechanical properties of the joint, but also could be simpler than the finite element solid model, which is convenient for application in practical projects, and provided a reliable reference and basis for the design of nonlinear semi-rigid joints of steel structure beams and columns.
In order to discuss the accuracy of the shape factor of the three-parameter power function moment-rotation curves of semi-rigid steel beam-column joints, the finite element software ANSYS was used to simulate and analyze. The finite element solid model and the three-parameter power function model based on the component method were established respectively for the typical semi-rigid joints of the extended end plate, which were verified with the test results. Based on the Weber distribution, the practical calculation formula of the shape factor of the semi-rigid connection of the extended end plate was fitted through the finite element solid model and the three-parameter power function model based on the component method. The results showed that the formula for calculating the shape factor of semi-rigid connections with extended end plates based on Weber distribution was more accurate than the existing formula; by giving COMBIN39 element a simplified finite element model of bending moment-rotation curves obtained from the three parameter power function based on the comporent method, the design could not only accurately simulate the mechanical properties of the joint, but also could be simpler than the finite element solid model, which is convenient for application in practical projects, and provided a reliable reference and basis for the design of nonlinear semi-rigid joints of steel structure beams and columns.
2025, 55(2): 146-155.
doi: 10.3724/j.gyjzG22101602
Abstract:
In order to study the axial tensile properties of reinforced low-grade magnesium ores concrete-filled circular steel tubes, explore the feasibility of low-grade magnesite concrete as the core concrete of steel tube axial tensile specimens and the influence of longitudinal reinforcement on the axial tensile properties of concrete-filled steel tube specimens, the axial tensile tests and corresponding push-out tests of 8 specimens were carried out with whether reinforcement and concrete type as changing parameters. The results showed that the average strain at each measuring point of the outer wall of the steel tube increased linearly with the increase of axial loads, the maximum strain ratio at the upper, middle and lower measuring points was about 8∶4∶1, and the ultimate interface bond strength of low-grade magnesium ores concrete-filled steel tubes was 0.67-0.73 MPa, which was stronger than that of ordinary concrete(the conclusion only applies to C40 concrete); the specimen was broken at L/3 and L/4 sections, and the section was a horizontal crack; the ultimate bearing capacity of concrete filled with low-grade magnesium ores was about 5% higher than that of ordinary concrete; the inner longitudinal reinforcement could effectively improve the ultimate bearing capacity of the specimen, and the inner longitudinal reinforcement had yielded when the specimen reached the ultimate bearing capacity; finally, based on the calculation formula of axial tensile capacity of concrete-filled circular steel tubes fitted by the research group in the early stage, a new calculation formula of axial tensile capacity of reinforced concrete-filled circular steel tubes related to the ratio of the wall thickness tothe diameter of the steel tube was proposed. The error between calculation results and test data was 2.2%, and the accuracy was high.
In order to study the axial tensile properties of reinforced low-grade magnesium ores concrete-filled circular steel tubes, explore the feasibility of low-grade magnesite concrete as the core concrete of steel tube axial tensile specimens and the influence of longitudinal reinforcement on the axial tensile properties of concrete-filled steel tube specimens, the axial tensile tests and corresponding push-out tests of 8 specimens were carried out with whether reinforcement and concrete type as changing parameters. The results showed that the average strain at each measuring point of the outer wall of the steel tube increased linearly with the increase of axial loads, the maximum strain ratio at the upper, middle and lower measuring points was about 8∶4∶1, and the ultimate interface bond strength of low-grade magnesium ores concrete-filled steel tubes was 0.67-0.73 MPa, which was stronger than that of ordinary concrete(the conclusion only applies to C40 concrete); the specimen was broken at L/3 and L/4 sections, and the section was a horizontal crack; the ultimate bearing capacity of concrete filled with low-grade magnesium ores was about 5% higher than that of ordinary concrete; the inner longitudinal reinforcement could effectively improve the ultimate bearing capacity of the specimen, and the inner longitudinal reinforcement had yielded when the specimen reached the ultimate bearing capacity; finally, based on the calculation formula of axial tensile capacity of concrete-filled circular steel tubes fitted by the research group in the early stage, a new calculation formula of axial tensile capacity of reinforced concrete-filled circular steel tubes related to the ratio of the wall thickness tothe diameter of the steel tube was proposed. The error between calculation results and test data was 2.2%, and the accuracy was high.
2025, 55(2): 156-165.
doi: 10.3724/j.gyjzG22120407
Abstract:
In order to improve the mechanical properties of the negative bending moment zone of steel UHPC waffle bridge decks, a staggered joint was proposed against the background of Wenchang Bridge, and four groups of steel UHPC waffle bridge deck joint specimens were designed and manufactured for bending tests. The effects of different factors, such as steel fiber type and joint type, on the failure mode, bearing capacity, reinforcement strain, crack extension and other properties of the specimens were compared and analyzed. The mechanical properties of the steel UHPC wiffle bridge deck undered the normal service limit state and bearing capacity limit state were evaluated and analyzed. The results showed that the specimens showed typical ductile bending failure, and the cracks were concentrated below the loading point and in the joint area; both staggered joints and end hook fibers could effectively improve the bearing capacity and deformation capacity of specimens; there were two stages in the crack development curve of each specimen: crack holding and force holding. When the crack width was 3 mm, the load borne by butted joint specimen DD was 14.8% higher than that of DZ, while the staggered joint specimen CD was only 5.3% higher than that of CZ; in the serviceability limit state and bearing capacity limit state, UHPC waffle bridge deck had excellent bearing performance, and met the design requirements of "strong joints, weak members".
In order to improve the mechanical properties of the negative bending moment zone of steel UHPC waffle bridge decks, a staggered joint was proposed against the background of Wenchang Bridge, and four groups of steel UHPC waffle bridge deck joint specimens were designed and manufactured for bending tests. The effects of different factors, such as steel fiber type and joint type, on the failure mode, bearing capacity, reinforcement strain, crack extension and other properties of the specimens were compared and analyzed. The mechanical properties of the steel UHPC wiffle bridge deck undered the normal service limit state and bearing capacity limit state were evaluated and analyzed. The results showed that the specimens showed typical ductile bending failure, and the cracks were concentrated below the loading point and in the joint area; both staggered joints and end hook fibers could effectively improve the bearing capacity and deformation capacity of specimens; there were two stages in the crack development curve of each specimen: crack holding and force holding. When the crack width was 3 mm, the load borne by butted joint specimen DD was 14.8% higher than that of DZ, while the staggered joint specimen CD was only 5.3% higher than that of CZ; in the serviceability limit state and bearing capacity limit state, UHPC waffle bridge deck had excellent bearing performance, and met the design requirements of "strong joints, weak members".
2025, 55(2): 166-176.
doi: 10.3724/j.gyjzG22121304
Abstract:
Steel-concrete composite structures have been more and more widely used in engineering due to their good mechanical properties; shear connectors are very important to ensure the joint stress of steel structures and concrete structures. A double-folded steel plate shear connector with flanges was proposed to obtain better bearing capacity and deformation. The push-out test for double-fold steel plate shear connectors was designed and carried out, and the mechanical properties of double-fold steel plate shear connectors and ordinary studs were compared and analyzed. Based on the push-out test results, a finite element model was established. The influence of parameters of folded plate height, thickness and opening diameter on the mechanical properties of shear connector was further obtained. The main conclusions were as follows: the double-folded shear connector showed semi-rigidity: compared with studs, the slip load was increased by more than 60%, and the ultimate bearing capacity was increased by about 50%. At the same time, it had better deformation and had a larger restraint area; the strain distribution of concrete restrained by double-fold steel plate shear onnectors was relatively uniform. Under the same loading condition, the strain value was smaller, indicating that the shear connector was better combined with the concrete slab, and the force transmission was more uniform. As the thickness of the folded plate increased, the ultimate bearing capacity of the shear connector was increased obviously, but its deformation did not change obviously. When the height of folded plate decreased to less than 80 mm, the bearing capacity was improved, but the deformation was reduced. The larger the opening diameter was, the lower the bearing capacity of the shear connector was, and the deformation showed a trend of increasing first and then decreasing; finally, a more reasonable design size of the double-fold steel plate shear connector was obtained: 6 mm thick, 80-90 mm high and 25 mm opening diameter.
Steel-concrete composite structures have been more and more widely used in engineering due to their good mechanical properties; shear connectors are very important to ensure the joint stress of steel structures and concrete structures. A double-folded steel plate shear connector with flanges was proposed to obtain better bearing capacity and deformation. The push-out test for double-fold steel plate shear connectors was designed and carried out, and the mechanical properties of double-fold steel plate shear connectors and ordinary studs were compared and analyzed. Based on the push-out test results, a finite element model was established. The influence of parameters of folded plate height, thickness and opening diameter on the mechanical properties of shear connector was further obtained. The main conclusions were as follows: the double-folded shear connector showed semi-rigidity: compared with studs, the slip load was increased by more than 60%, and the ultimate bearing capacity was increased by about 50%. At the same time, it had better deformation and had a larger restraint area; the strain distribution of concrete restrained by double-fold steel plate shear onnectors was relatively uniform. Under the same loading condition, the strain value was smaller, indicating that the shear connector was better combined with the concrete slab, and the force transmission was more uniform. As the thickness of the folded plate increased, the ultimate bearing capacity of the shear connector was increased obviously, but its deformation did not change obviously. When the height of folded plate decreased to less than 80 mm, the bearing capacity was improved, but the deformation was reduced. The larger the opening diameter was, the lower the bearing capacity of the shear connector was, and the deformation showed a trend of increasing first and then decreasing; finally, a more reasonable design size of the double-fold steel plate shear connector was obtained: 6 mm thick, 80-90 mm high and 25 mm opening diameter.
2025, 55(2): 177-186.
doi: 10.3724/j.gyjzG24091401
Abstract:
In order to investigate the axially-loaded mechanical properties of the tuned-mass type composite columns (TMTCCs), 7 groups (each group had 2 specimens) of TMTCC specimens were designed and prepared, and experimental and numerical studies were conducted in the paper. The influences of length-to-diameter ratio and diameter-to-thickness ratio on its bearing capacity were studied as well. Moreover, according to the Technical Code for Concrete Filled Steel Tubular Structures (GB 50936—2014) and Technical Specification for Concrete-Filled Double Skin Steel Tubular structures (T/CCES 7—2020), the prediction formula of the ultimate axial load-bearing capacity of TMTCC under axial compression was developed and verified by experimental and numerical results. The results showed that the ultimate bearing capacity of TMTCC specimens under axial compression tended to decrease with the increase of length-to-diameter ratio and diameter-to-thickness ratio. By adopting the springs and dashpots, the internal and external columns of TMTCC could work together to bear the vertical loading and hence effectively prevented the sliding, tilting and global buckling of the internal column. The obtained numerical and predicted results were in good agreements with the experimental results, which can be used for the analysis and design of TMTCC.
In order to investigate the axially-loaded mechanical properties of the tuned-mass type composite columns (TMTCCs), 7 groups (each group had 2 specimens) of TMTCC specimens were designed and prepared, and experimental and numerical studies were conducted in the paper. The influences of length-to-diameter ratio and diameter-to-thickness ratio on its bearing capacity were studied as well. Moreover, according to the Technical Code for Concrete Filled Steel Tubular Structures (GB 50936—2014) and Technical Specification for Concrete-Filled Double Skin Steel Tubular structures (T/CCES 7—2020), the prediction formula of the ultimate axial load-bearing capacity of TMTCC under axial compression was developed and verified by experimental and numerical results. The results showed that the ultimate bearing capacity of TMTCC specimens under axial compression tended to decrease with the increase of length-to-diameter ratio and diameter-to-thickness ratio. By adopting the springs and dashpots, the internal and external columns of TMTCC could work together to bear the vertical loading and hence effectively prevented the sliding, tilting and global buckling of the internal column. The obtained numerical and predicted results were in good agreements with the experimental results, which can be used for the analysis and design of TMTCC.
2025, 55(2): 187-194.
doi: 10.3724/j.gyjzG22112816
Abstract:
Based on the particle flow theory, the numerical simulation of inter-embedded settlement of miscellaneous fills and soft soil was conducted by using the EDEM calculation software. In the case of 10 mm, 30 mm, and 50 mm particle sizes of miscellaneous fills, the influence of particle sizes of miscellaneous fills on mutual-embedding was studied by analyzing the velocity field, displacement field and stress field of soft soil particles during the mutual-embedding process. The research results indicated that when the particle size of the miscellaneous fill was large, the velocity distribution of the soft soil particles was not uniform, and the velocity of the soft soil particles in the pore channels of the miscellaneous fill was relatively large. As the particle size of the miscellaneous fill decreased, the velocity distribution of the soft soil gradually became uniform, and the upward pressing force on the soft soil in the pore channel also decreased, resulting in a decrease in the mutual-embedded settlement. The mutual-embedded settlement of miscellaneous fills and soft soil particles was mainly affected by the soil layer on the soft soil surface. From a mechanical perspective, the reason for the mutual-embedding was that the direction of the contact force in the mutual-embedding was constantly changing, and the arch force chain was gradually developed, and the particles above the arch force chain were weak due to the weak force chain and the influence of the surrounding particles upward movement.
Based on the particle flow theory, the numerical simulation of inter-embedded settlement of miscellaneous fills and soft soil was conducted by using the EDEM calculation software. In the case of 10 mm, 30 mm, and 50 mm particle sizes of miscellaneous fills, the influence of particle sizes of miscellaneous fills on mutual-embedding was studied by analyzing the velocity field, displacement field and stress field of soft soil particles during the mutual-embedding process. The research results indicated that when the particle size of the miscellaneous fill was large, the velocity distribution of the soft soil particles was not uniform, and the velocity of the soft soil particles in the pore channels of the miscellaneous fill was relatively large. As the particle size of the miscellaneous fill decreased, the velocity distribution of the soft soil gradually became uniform, and the upward pressing force on the soft soil in the pore channel also decreased, resulting in a decrease in the mutual-embedded settlement. The mutual-embedded settlement of miscellaneous fills and soft soil particles was mainly affected by the soil layer on the soft soil surface. From a mechanical perspective, the reason for the mutual-embedding was that the direction of the contact force in the mutual-embedding was constantly changing, and the arch force chain was gradually developed, and the particles above the arch force chain were weak due to the weak force chain and the influence of the surrounding particles upward movement.
2025, 55(2): 195-205.
doi: 10.3724/j.gyjzG23101705
Abstract:
The effect of the traditional vacuum preloading method is often not ideal when treating engineering waste slurry, and the vertical drainage plate is easy to bend and deform. To improve the effect of drainage consolidation, consider the respective treatment characteristics of horizontal drainage plates and vertical drainage plates in the vacuum preloading method. The method of vacuum preloading and layered treatment for engineering waste slurry combined horizontal drains with vertical drains was proposed. Through 6 groups of indoor model tests, the advantages and disadvantages of three vacuum preloading methods, namely horizontal drainage plates-vacuum preloading method (PHDs), vertical drainage plates-vacuum preloading method (PVDs). and horizontal combined vertical drainage plate-vacuum preloading method (the combination of PHDs and PVDs), were studied and analyzed, and a more efficient vacuum preloading method was selected to treat engineering waste slurry. The test results of vacuum degree, pore water pressure dissipation, soil surface settlement, cumulative water discharge, vacuum, soil moisture content and cross plate shear strength after vacuum consolidation were compared and studied in different test groups. The test results showed that when PVDs were used, the bottom treatment effect was not ideal, and the reinforcement effect of the general soil was weakening along the depth of the soil layer. When the combination of PHDs and PVDs was used, the reinforcement effect of deep soil could be effectively improved, and the heap stress provided by the high vacuum pressure and the self-weight of the upper soil could effectively promote the vacuum consolidation of the bottom soil. When PHDs were used, the overall reinforcement effect was better than that of PVDs, but the drainage path in the middle of each two layers of drainage boards and the surface of the soil layer was longer, resulting in poor treatment effect. When the combination of PHDs and PVDs was used, the strength of the upper and bottom soil could be improved at the same time, making the overall treatment effect was more uniform, the strength of the upper soil and the bottom soil could be improved at the same time, so that the overall treatment effect was more uniform. The average strength of soil could reach 18 kPa to 24 kPa, which was about 20% higher than the overall treatment effect of PHDs and 25% to 35% higher than that of PVDs.
The effect of the traditional vacuum preloading method is often not ideal when treating engineering waste slurry, and the vertical drainage plate is easy to bend and deform. To improve the effect of drainage consolidation, consider the respective treatment characteristics of horizontal drainage plates and vertical drainage plates in the vacuum preloading method. The method of vacuum preloading and layered treatment for engineering waste slurry combined horizontal drains with vertical drains was proposed. Through 6 groups of indoor model tests, the advantages and disadvantages of three vacuum preloading methods, namely horizontal drainage plates-vacuum preloading method (PHDs), vertical drainage plates-vacuum preloading method (PVDs). and horizontal combined vertical drainage plate-vacuum preloading method (the combination of PHDs and PVDs), were studied and analyzed, and a more efficient vacuum preloading method was selected to treat engineering waste slurry. The test results of vacuum degree, pore water pressure dissipation, soil surface settlement, cumulative water discharge, vacuum, soil moisture content and cross plate shear strength after vacuum consolidation were compared and studied in different test groups. The test results showed that when PVDs were used, the bottom treatment effect was not ideal, and the reinforcement effect of the general soil was weakening along the depth of the soil layer. When the combination of PHDs and PVDs was used, the reinforcement effect of deep soil could be effectively improved, and the heap stress provided by the high vacuum pressure and the self-weight of the upper soil could effectively promote the vacuum consolidation of the bottom soil. When PHDs were used, the overall reinforcement effect was better than that of PVDs, but the drainage path in the middle of each two layers of drainage boards and the surface of the soil layer was longer, resulting in poor treatment effect. When the combination of PHDs and PVDs was used, the strength of the upper and bottom soil could be improved at the same time, making the overall treatment effect was more uniform, the strength of the upper soil and the bottom soil could be improved at the same time, so that the overall treatment effect was more uniform. The average strength of soil could reach 18 kPa to 24 kPa, which was about 20% higher than the overall treatment effect of PHDs and 25% to 35% higher than that of PVDs.
2025, 55(2): 206-215.
doi: 10.3724/j.gyjzG22110711
Abstract:
The landfill leachate sludge produced by submerged combustion process has the characteristics of low organic matter content and heavy metal content but high liquid index and salt content. Ordinary Portland cement and sulphoaluminate cement with different cement types and cement contents were used to solidifiy leachate sludge. The unconfined compressive strength test and immersion test were carried out to evaluate the reinforcement effect of cement on the strength and water stability of high-salt-content leachate sludge. Meanwhile, microscopy tests were carried out on the solidified sludge samples to explore the micro-control mechanism of cement solidification effect. The test results showed that: 1) the curing effect of ordinary Portland cement on sludge with high-salt-content leachate was non-ideal;2) the unconfined compressive strength of solidified sludge with 10% sulfoaluminate cement content for 28 d curing age met the strength requirement of solidified sludge landfills; 3) when the content of sulphoaluminate cement was more than 50%, the unconfined compressive strength of solidified sludge with curing age of 28 days after being immersed for 28 days could meet the landfill requirement of 50 kPa;4) C-S-H gel with cementing effect produced by the addition of sulphoaluminate cement caused the microstructure of the sludge to be more compact, which was the micro-control mechanism for the strength enhancement of sludge in sulphoaluminate cement solidified leachate with high salt content; 5) the soluble salt sludge particles in the sample solidified by sulphoaluminate cement gradually dissolved with the increase of immersion time, which led to the fracture and dispersion of C-S-H gel and the destruction of micro-cementing morphology, it was the micro-control mechanism for the immersion deterioration of sulphoaluminate cement solidified high-salt leachate sludge.
The landfill leachate sludge produced by submerged combustion process has the characteristics of low organic matter content and heavy metal content but high liquid index and salt content. Ordinary Portland cement and sulphoaluminate cement with different cement types and cement contents were used to solidifiy leachate sludge. The unconfined compressive strength test and immersion test were carried out to evaluate the reinforcement effect of cement on the strength and water stability of high-salt-content leachate sludge. Meanwhile, microscopy tests were carried out on the solidified sludge samples to explore the micro-control mechanism of cement solidification effect. The test results showed that: 1) the curing effect of ordinary Portland cement on sludge with high-salt-content leachate was non-ideal;2) the unconfined compressive strength of solidified sludge with 10% sulfoaluminate cement content for 28 d curing age met the strength requirement of solidified sludge landfills; 3) when the content of sulphoaluminate cement was more than 50%, the unconfined compressive strength of solidified sludge with curing age of 28 days after being immersed for 28 days could meet the landfill requirement of 50 kPa;4) C-S-H gel with cementing effect produced by the addition of sulphoaluminate cement caused the microstructure of the sludge to be more compact, which was the micro-control mechanism for the strength enhancement of sludge in sulphoaluminate cement solidified leachate with high salt content; 5) the soluble salt sludge particles in the sample solidified by sulphoaluminate cement gradually dissolved with the increase of immersion time, which led to the fracture and dispersion of C-S-H gel and the destruction of micro-cementing morphology, it was the micro-control mechanism for the immersion deterioration of sulphoaluminate cement solidified high-salt leachate sludge.
2025, 55(2): 216-222.
doi: 10.3724/j.gyjzG23060407
Abstract:
In subgrade slope engineering, latticed skeleton slope protection is the most common, but the temperature difference between day and night is large in northern China, resulting in the weakening of slope supporting capacity. In order to study the impact compression test of the basalt after freezing and thawing of the slope rock, the number of freeze-thaw cycles, different curing states and different dynamic impact velocities were selected as typical working conditions to analyze and discuss the influence of the mechanical properties of Hopkinson basalt on the freeze-thaw cycle, and to ensure that the slope in the cold region has good compressive performance under impact loading, the influence of 50 mm diameter separated Hopkinson pressure rod on the dynamic strength of the freeze-thaw cycles was analyzed. The experimental results showed that with the increase of impact velocity, the dynamic compressive strength of each rock sample showed a linear growth trend. Under the same strain rate and the same number of freeze-thaw cycles, the freezing curing environment had an enhanced effect on the bearing capacity of rock samples, and the saturated conservation environment had a softening effect on the bearing capacity of rock samples, and the peak strength of dynamic compressive resistance in freezing environment was the largest, and the strength of saturated state was the smallest, and the two intensity factors gradually approached 1 with the increase of freeze-thaw cycles. The change of strain rate of the dynamic strength of rock samples was most significant in the early stage due to the weakening effect of freeze-thaw cycles. With the increase number of freeze-thaw cycles, the strain of saturated specimens gradually increased, and the peak stress gradually decreased. In the late stage of freezing and thawing, the strength change and strain rate effect of rock samples were gradually weakening.
In subgrade slope engineering, latticed skeleton slope protection is the most common, but the temperature difference between day and night is large in northern China, resulting in the weakening of slope supporting capacity. In order to study the impact compression test of the basalt after freezing and thawing of the slope rock, the number of freeze-thaw cycles, different curing states and different dynamic impact velocities were selected as typical working conditions to analyze and discuss the influence of the mechanical properties of Hopkinson basalt on the freeze-thaw cycle, and to ensure that the slope in the cold region has good compressive performance under impact loading, the influence of 50 mm diameter separated Hopkinson pressure rod on the dynamic strength of the freeze-thaw cycles was analyzed. The experimental results showed that with the increase of impact velocity, the dynamic compressive strength of each rock sample showed a linear growth trend. Under the same strain rate and the same number of freeze-thaw cycles, the freezing curing environment had an enhanced effect on the bearing capacity of rock samples, and the saturated conservation environment had a softening effect on the bearing capacity of rock samples, and the peak strength of dynamic compressive resistance in freezing environment was the largest, and the strength of saturated state was the smallest, and the two intensity factors gradually approached 1 with the increase of freeze-thaw cycles. The change of strain rate of the dynamic strength of rock samples was most significant in the early stage due to the weakening effect of freeze-thaw cycles. With the increase number of freeze-thaw cycles, the strain of saturated specimens gradually increased, and the peak stress gradually decreased. In the late stage of freezing and thawing, the strength change and strain rate effect of rock samples were gradually weakening.
2025, 55(2): 223-232.
doi: 10.3724/j.gyjzG24072602
Abstract:
In order to study the effect of cement and polypropylene fibers combined stabilization on the mechanical properties of marine silt soft soil, factors such as cement content (5%, 10%, 15%, 20%), fiber length (6, 9, 12, 15 mm), and fiber content (0.2%, 0.4%, 0.6%) were considered. Unconfined compressive tests were conducted on marine silt soft soil stabilized with fibers and cement. The optimal fiber length and fiber content were selected, and the soil at the crack site was collected for SEM and XRD analysis. The experimental results showed that the failure modes of the only cement-stabilized soil and the cement and fiber combined stalilization soil were brittle failure and plastic failure, respectively, and the latter also had a relatively large residual strength; with the increase of fiber content, the strength of the stablized soil first increased and then decreased, and there exists an optimal content; when the cement content did not exceed 15%, the optimal fiber content was 0.4%. When the cement content was 20%, the optimal fiber content was 0.2%; compared with other lengths of fibers (6, 9, 15 mm), fibers with a length of 12 mm had the best stabilization effect on cement soil; with the increase of cement content, the strength of the stabilized soil increased almost linearly. When the cement content increased from 5% to 20%, the strength of the non-fiber soil increased by 15% to 20%, while the strength of the soil added with polypropylene fibers increases by 15% to 20%. From microscopic analysis, it could be concluded that the strength of cement stabilized soil mainly comes from the bonding effect of hydrates produced by the hydration of cement and water in the sludge.
In order to study the effect of cement and polypropylene fibers combined stabilization on the mechanical properties of marine silt soft soil, factors such as cement content (5%, 10%, 15%, 20%), fiber length (6, 9, 12, 15 mm), and fiber content (0.2%, 0.4%, 0.6%) were considered. Unconfined compressive tests were conducted on marine silt soft soil stabilized with fibers and cement. The optimal fiber length and fiber content were selected, and the soil at the crack site was collected for SEM and XRD analysis. The experimental results showed that the failure modes of the only cement-stabilized soil and the cement and fiber combined stalilization soil were brittle failure and plastic failure, respectively, and the latter also had a relatively large residual strength; with the increase of fiber content, the strength of the stablized soil first increased and then decreased, and there exists an optimal content; when the cement content did not exceed 15%, the optimal fiber content was 0.4%. When the cement content was 20%, the optimal fiber content was 0.2%; compared with other lengths of fibers (6, 9, 15 mm), fibers with a length of 12 mm had the best stabilization effect on cement soil; with the increase of cement content, the strength of the stabilized soil increased almost linearly. When the cement content increased from 5% to 20%, the strength of the non-fiber soil increased by 15% to 20%, while the strength of the soil added with polypropylene fibers increases by 15% to 20%. From microscopic analysis, it could be concluded that the strength of cement stabilized soil mainly comes from the bonding effect of hydrates produced by the hydration of cement and water in the sludge.
2025, 55(2): 233-239.
doi: 10.3724/j.gyjzG22120807
Abstract:
In order to study the seismic performance of centrifugal concrete-filled steel tubular piles (SC tube piles) and consider the influence of core filling and prestress, the quasi-static tests were carried out on 3 SC tubular piles and 2 prestressed high-strength concrete tubular piles (PHC tube piles). The results showed that the seismic bearing capacity, yield displacement, ultimate displacement and ductility coefficient of SC tubular piles were 2.85 times, 1.97 times, 2.47 times and 1.47 times of PHC tubular piles, respectively, the energy consumption coefficient was about 4.5 times of PHC tubular piles, and the total energy consumption was 32 times of PHC tubular piles, the cut line stiffness of SC tubular piles in the same displacement conditions was about 2-3 times that of PHC tubular piles, and the displacement of SC tubular piles when the bearing capacity dropped steeply was about 2.4 times that of PHC tubular piles; the seismic bearing capacity of prestressed SC tubular piles was about 15% higher than that of SC tubular piles; the effect of concrete filling on the seismic performance of SC tubular piles was negligible.
In order to study the seismic performance of centrifugal concrete-filled steel tubular piles (SC tube piles) and consider the influence of core filling and prestress, the quasi-static tests were carried out on 3 SC tubular piles and 2 prestressed high-strength concrete tubular piles (PHC tube piles). The results showed that the seismic bearing capacity, yield displacement, ultimate displacement and ductility coefficient of SC tubular piles were 2.85 times, 1.97 times, 2.47 times and 1.47 times of PHC tubular piles, respectively, the energy consumption coefficient was about 4.5 times of PHC tubular piles, and the total energy consumption was 32 times of PHC tubular piles, the cut line stiffness of SC tubular piles in the same displacement conditions was about 2-3 times that of PHC tubular piles, and the displacement of SC tubular piles when the bearing capacity dropped steeply was about 2.4 times that of PHC tubular piles; the seismic bearing capacity of prestressed SC tubular piles was about 15% higher than that of SC tubular piles; the effect of concrete filling on the seismic performance of SC tubular piles was negligible.
2025, 55(2): 240-245.
doi: 10.3724/j.gyjzG22111905
Abstract:
In order to avoid accidents and geological disasters, it is very important to reasonably evaluate the stability of underground air-raid shelters in the construction of new cities and renovation of old cities. According to the engineering geological conditions of the masonry air-raid shelter in the city, the paper selected a typical section, used the Platts unloading arch theory to calculate the vertical stress of the vault and the horizontal stress of the side wall, and used the MIDAS GTS/NX software stratum structure method. The finite element modeling was carried out, and the relative errors of the results obtained by the two methods were 6.90% and 6.71%, respectively. According to the specification, the compressive bearing capacity of the masonry air-raid shelter was checked, and the results showed that both the vertical stress of the vault and the horizontal stress of the side walls met the compressive bearing capacity requirements. Considering the seepage of the soil around the masonry air-raid shelter and the requirements of shear and bending bearing capacity, the masonry air-raid shelter should be partially reinforced and grouted.
In order to avoid accidents and geological disasters, it is very important to reasonably evaluate the stability of underground air-raid shelters in the construction of new cities and renovation of old cities. According to the engineering geological conditions of the masonry air-raid shelter in the city, the paper selected a typical section, used the Platts unloading arch theory to calculate the vertical stress of the vault and the horizontal stress of the side wall, and used the MIDAS GTS/NX software stratum structure method. The finite element modeling was carried out, and the relative errors of the results obtained by the two methods were 6.90% and 6.71%, respectively. According to the specification, the compressive bearing capacity of the masonry air-raid shelter was checked, and the results showed that both the vertical stress of the vault and the horizontal stress of the side walls met the compressive bearing capacity requirements. Considering the seepage of the soil around the masonry air-raid shelter and the requirements of shear and bending bearing capacity, the masonry air-raid shelter should be partially reinforced and grouted.
2025, 55(2): 246-253.
doi: 10.3724/j.gyjzG24043004
Abstract:
In order to study the time-varying temperature effect of hydration heat of ultra-high strength mass concrete, a finite element model was established based on the anchor foundation of a high tower of Dubai River. Through simulations, the characteristics of temperature distribution of hydration heat of ultra-high strength concrete (C90/105) were obtained, and the pipe cooling system was optimized for temperature control. On this basis, the time-varying temperature effect of hydration heat of ultra-high strength concrete was studied by changing the concrete pouring temperature and the inlet temperature of pipe cooling. The results indicated that the peak surface temperature, the peak internal temperature, and temperature difference between the interior and the surface of the structure were approximately positively correlated with the concrete pouring temperature, and for each 5 ℃ decrease in the pouring temperature, the average maximum temperature difference between the interior and the surface of the concrete structure decreased by approximately 2 ℃. For each 5 ℃ decrease in the inlet temperature of pipe cooling, the average maximum temperature difference between the interior and the surface of the concrete structure diminished by approximately 5 ℃. However, if the inlet temperature was substantially lower than the concrete pouring temperature, the internal temperature of the structure might become lower than the surface temperature. In practical engineering, the reasonable design of ultra-high strength concrete structure and pipe cooling system should be taken into account the requirements of temperature control and resource utilization.
In order to study the time-varying temperature effect of hydration heat of ultra-high strength mass concrete, a finite element model was established based on the anchor foundation of a high tower of Dubai River. Through simulations, the characteristics of temperature distribution of hydration heat of ultra-high strength concrete (C90/105) were obtained, and the pipe cooling system was optimized for temperature control. On this basis, the time-varying temperature effect of hydration heat of ultra-high strength concrete was studied by changing the concrete pouring temperature and the inlet temperature of pipe cooling. The results indicated that the peak surface temperature, the peak internal temperature, and temperature difference between the interior and the surface of the structure were approximately positively correlated with the concrete pouring temperature, and for each 5 ℃ decrease in the pouring temperature, the average maximum temperature difference between the interior and the surface of the concrete structure decreased by approximately 2 ℃. For each 5 ℃ decrease in the inlet temperature of pipe cooling, the average maximum temperature difference between the interior and the surface of the concrete structure diminished by approximately 5 ℃. However, if the inlet temperature was substantially lower than the concrete pouring temperature, the internal temperature of the structure might become lower than the surface temperature. In practical engineering, the reasonable design of ultra-high strength concrete structure and pipe cooling system should be taken into account the requirements of temperature control and resource utilization.
Experimental Research on the Fatigue Damage Characteristics of CFRP Plate-Concrete Bonding Interface
2025, 55(2): 254-262.
doi: 10.3724/j.gyjzG24091902
Abstract:
When concrete structures reinforced with externally bonded carbon fiber reinforced polymer (CFRP) are subjected to fatigue loads, damage accumulates continuously on the bonding interface layer between the CFRP plate and concrete, and manifests macroscopically as performance degradation of the interface layer. This study conducted fatigue performance tests on the bonding interface between CFRP plates and concrete through in-plane shear tests. The relative slip changes between CFRP plates and concrete matrix were observed in detail, and the stiffness degradation behavior of the bonding interface and the energy dissipation process of the interface layer were analyzed. It was found that the attenuation of these interface performance indicators was mainly concentrated in the first 10% of the fatigue life of the specimens, and tended to stabilize during the subsequent loading process. The energy dissipation capacity of the bonding interface layer also rapidly weakened and tended to stabilize with the continuous fatigue loading. This study found that the stiffness attenuation rate Ds of the CFRP plate concrete bonding interface under fatigue loading exhibited a strong linear relation with the stress condition S of the bonding interface in a double logarithmic coordinate system, and a formula for calculating the stiffness attenuation rate of the interface was proposed.
When concrete structures reinforced with externally bonded carbon fiber reinforced polymer (CFRP) are subjected to fatigue loads, damage accumulates continuously on the bonding interface layer between the CFRP plate and concrete, and manifests macroscopically as performance degradation of the interface layer. This study conducted fatigue performance tests on the bonding interface between CFRP plates and concrete through in-plane shear tests. The relative slip changes between CFRP plates and concrete matrix were observed in detail, and the stiffness degradation behavior of the bonding interface and the energy dissipation process of the interface layer were analyzed. It was found that the attenuation of these interface performance indicators was mainly concentrated in the first 10% of the fatigue life of the specimens, and tended to stabilize during the subsequent loading process. The energy dissipation capacity of the bonding interface layer also rapidly weakened and tended to stabilize with the continuous fatigue loading. This study found that the stiffness attenuation rate Ds of the CFRP plate concrete bonding interface under fatigue loading exhibited a strong linear relation with the stress condition S of the bonding interface in a double logarithmic coordinate system, and a formula for calculating the stiffness attenuation rate of the interface was proposed.
2025, 55(2): 263-270.
doi: 10.3724/j.gyjzG22031614
Abstract:
To study the mechanical properties of steel truss support platform during the construction of the roof of large-scale silos, taking a silo project in Guangdong province as an example, the force condition of steel support platform was monitored during the whole concrete pouring process on the silo roof. The results showed that, because the lifting points were not at the same horizontal height, the maximum stable stress ratio of the main components of the platform was 0.25 during the lifting process. In the concrete pouring process of the inclined shell roof, the stable stress ratio of the main components was not more than 0.58, and the maximum vertical deflection of the support platform was 22 mm. In the process of concrete pouring of the top flat roof, the maximum stress of the support platform was less than 18 MPa because the concrete of inclined shell roof had hardened and could bear the most vertical load. The above indicated that the support platform had enough safety reserve and could be optimized. Finally, the silo roof construction process was simulated by using the ABAQUS software. On the whole, the simulated results agreed well with the measured results which indicated that the numerical method could be used to study the mechanical properties of steel truss support platform during the construction of the roof of large-scale silos.
To study the mechanical properties of steel truss support platform during the construction of the roof of large-scale silos, taking a silo project in Guangdong province as an example, the force condition of steel support platform was monitored during the whole concrete pouring process on the silo roof. The results showed that, because the lifting points were not at the same horizontal height, the maximum stable stress ratio of the main components of the platform was 0.25 during the lifting process. In the concrete pouring process of the inclined shell roof, the stable stress ratio of the main components was not more than 0.58, and the maximum vertical deflection of the support platform was 22 mm. In the process of concrete pouring of the top flat roof, the maximum stress of the support platform was less than 18 MPa because the concrete of inclined shell roof had hardened and could bear the most vertical load. The above indicated that the support platform had enough safety reserve and could be optimized. Finally, the silo roof construction process was simulated by using the ABAQUS software. On the whole, the simulated results agreed well with the measured results which indicated that the numerical method could be used to study the mechanical properties of steel truss support platform during the construction of the roof of large-scale silos.
