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2023 Vol. 53, No. 3
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2023, 53(3): 1-11,20.
doi: 10.13204/j.gyjzG22083114
Abstract:
Studies related to the corrosion performance of prestressing tendons under the influence of stress are reviewed in terms of both corrosion phenomena and corrosion effects. The study of corrosion phenomena focuses on the entire development process, including corrosion initiation and pitting formation, pitting evolution and crack nucleation, crack expansion and metal fracture. The presence of stress affects pitting susceptibility by influencing the formation and destruction of the passivation film. By the evolution of pitting, the formation of microcracks at the etch pits is a typical feature of stress corrosion cracking, and by analysing the fracture morphology can determine this fracture mode. The study of corrosion effect concentrates on the degradation of mechanical properties of prestressing tendons with stress history corrosion. The result shows the strength and ductility are reduced to different degrees, and further research is needed on the effect law of stress level/stress amplitude on property degradation.
Studies related to the corrosion performance of prestressing tendons under the influence of stress are reviewed in terms of both corrosion phenomena and corrosion effects. The study of corrosion phenomena focuses on the entire development process, including corrosion initiation and pitting formation, pitting evolution and crack nucleation, crack expansion and metal fracture. The presence of stress affects pitting susceptibility by influencing the formation and destruction of the passivation film. By the evolution of pitting, the formation of microcracks at the etch pits is a typical feature of stress corrosion cracking, and by analysing the fracture morphology can determine this fracture mode. The study of corrosion effect concentrates on the degradation of mechanical properties of prestressing tendons with stress history corrosion. The result shows the strength and ductility are reduced to different degrees, and further research is needed on the effect law of stress level/stress amplitude on property degradation.
2023, 53(3): 12-20.
doi: 10.13204/j.gyjzG22082911
Abstract:
Prestressed concrete double tees set precast structural characteristics and good mechanical properties, widely used in large-span industrial and public buildings at home and abroad. Based on the current research and application status of prestressed concrete double tees in China and abroad, this paper summaries the structural performance research and engineering applications progress of prestressed concrete double tees, and introduces the research progress in key areas such as mechanical behavior, connection and disaster resistance. The key points of design and calculation of double tees and some representative engineering applications are shown. This paper also discusses the key development directions in the future such as high performance materials, new cross-sectional forms and matching technology in order to provide certain guidance for the future application and research direction of prestressed concrete double tees.
Prestressed concrete double tees set precast structural characteristics and good mechanical properties, widely used in large-span industrial and public buildings at home and abroad. Based on the current research and application status of prestressed concrete double tees in China and abroad, this paper summaries the structural performance research and engineering applications progress of prestressed concrete double tees, and introduces the research progress in key areas such as mechanical behavior, connection and disaster resistance. The key points of design and calculation of double tees and some representative engineering applications are shown. This paper also discusses the key development directions in the future such as high performance materials, new cross-sectional forms and matching technology in order to provide certain guidance for the future application and research direction of prestressed concrete double tees.
2023, 53(3): 21-28.
doi: 10.13204/j.gyjzG22083007
Abstract:
A series of experimental tests on prestress CFRP plate strengthened RC beams were conducted. The strengthening effect on undamaged beam and damaged beam of two types of strengthening methods, i.e., externally bonded prestressed CFRP and novel mid-span supporting prestressing technique, were investigated. The test results show that the novel strengthening method can enhance both cracking load and ultimate load effectively. The cracking load was enhanced by up to 100%, and the ultimate strength was increased by up to 48%, which had higher efficiency than the conventional method. In addition, the RC beam strengthened by the novel prestressing method had good ductility with a long yield plateau when subjected to bending. Hence, this is a valuable reference for further application of high-performance material in structural engineering.
A series of experimental tests on prestress CFRP plate strengthened RC beams were conducted. The strengthening effect on undamaged beam and damaged beam of two types of strengthening methods, i.e., externally bonded prestressed CFRP and novel mid-span supporting prestressing technique, were investigated. The test results show that the novel strengthening method can enhance both cracking load and ultimate load effectively. The cracking load was enhanced by up to 100%, and the ultimate strength was increased by up to 48%, which had higher efficiency than the conventional method. In addition, the RC beam strengthened by the novel prestressing method had good ductility with a long yield plateau when subjected to bending. Hence, this is a valuable reference for further application of high-performance material in structural engineering.
2023, 53(3): 29-34,28.
doi: 10.13204/j.gyjzG22081301
Abstract:
In order to study the seismic performance of the new dry-wet combined precast concrete beam-column joints with local post-tensioned tendons,a solid finite element model was established by ABAQUS software to simulate the joints with high strength steel reinforcement and steel ties for prestressing tendons,and to verify with the experimental results. Finally, parametric analysis was carried out on the relevant factors such as concrete strength grade, prestressing tendon tension and axial compression ratio. The results of the study show that the simulation results of the finite element model considering the slip of the reinforcement are in general agreement with the tests. The cumulative energy consumption of the joints with steel ties is about 41% of that of the joints with high-strength steel. When the concrete strength is increased from C30 to C50, the load carrying capacity of both joints increases by less than 5%. Compared with joints with high-strength steel, the increase of the prestressing tendons tension can significantly reduce the yield displacement of the joints with steel ties and improve its pre-strength, stiffness and ductility.Within the axial pressure ratio of 0.6, the increase of the axial pressure ratio only improve the ultimate load capacity of the joints with high-strength steel.
In order to study the seismic performance of the new dry-wet combined precast concrete beam-column joints with local post-tensioned tendons,a solid finite element model was established by ABAQUS software to simulate the joints with high strength steel reinforcement and steel ties for prestressing tendons,and to verify with the experimental results. Finally, parametric analysis was carried out on the relevant factors such as concrete strength grade, prestressing tendon tension and axial compression ratio. The results of the study show that the simulation results of the finite element model considering the slip of the reinforcement are in general agreement with the tests. The cumulative energy consumption of the joints with steel ties is about 41% of that of the joints with high-strength steel. When the concrete strength is increased from C30 to C50, the load carrying capacity of both joints increases by less than 5%. Compared with joints with high-strength steel, the increase of the prestressing tendons tension can significantly reduce the yield displacement of the joints with steel ties and improve its pre-strength, stiffness and ductility.Within the axial pressure ratio of 0.6, the increase of the axial pressure ratio only improve the ultimate load capacity of the joints with high-strength steel.
2023, 53(3): 35-40.
doi: 10.13204/j.gyjzG22083020
Abstract:
To investigate the influence of ground motion duration on the seismic response of self-centering prestressed concrete (SCPC) frames characterized by semi-rigidity, a friction based SCPC frame located in the area with a seismic fortification intensity of eight degree is selected as the analytical case, and its numerical model has been built. Two sets of artificial ground motions with 20 s and 60 s duration, generated based on code response spectrum, were used as the excitation for structures. The nonlinear dynamic analyses were performed on the SCPC frame under moderate and major earthquakes through finite element model of OpenSees. Results show that the ground motion duration has minor influence on the seismic response of structures under moderate earthquakes and the structures can be used immediately. Under major earthquakes, the structure can achieve the performance objective of repairable under the earthquake with short duration, while long ground motion duration may lead to larger displacement and residual deformation of lower floors, and aggravate the damage of beam and column, the objective of repairable under major earthquake is not achieved easily.
To investigate the influence of ground motion duration on the seismic response of self-centering prestressed concrete (SCPC) frames characterized by semi-rigidity, a friction based SCPC frame located in the area with a seismic fortification intensity of eight degree is selected as the analytical case, and its numerical model has been built. Two sets of artificial ground motions with 20 s and 60 s duration, generated based on code response spectrum, were used as the excitation for structures. The nonlinear dynamic analyses were performed on the SCPC frame under moderate and major earthquakes through finite element model of OpenSees. Results show that the ground motion duration has minor influence on the seismic response of structures under moderate earthquakes and the structures can be used immediately. Under major earthquakes, the structure can achieve the performance objective of repairable under the earthquake with short duration, while long ground motion duration may lead to larger displacement and residual deformation of lower floors, and aggravate the damage of beam and column, the objective of repairable under major earthquake is not achieved easily.
2023, 53(3): 41-47.
doi: 10.13204/j.gyjzG22062205
Abstract:
In the structural integrity test of the containment, the deformation of the containment is mainly caused by the test pressure and is also influenced by the ambient temperature, solar radiation and other comprehensive factors. In order to improve the deformation measurement accuracy of the test and make reasonable corrections, this paper investigates the influence law of ambient temperature, solar radiation, radiation heat exchange and different thermal boundary condition application methods on the deformation of the containment through finite element simulation analysis.The results show that the displacement of containment varies approximately sinusoidal with the ambient temperature, and lags behind the ambient temperature by about 2 h, and when the effect of solar radiation is ignored, the vertical average displacement amplitude of the dome is reduced by about 49% and the horizontal radial average displacement amplitude of the barrel is reduced by about 21%, indicating that the ambient temperature and solar radiation are the main environmental factors affecting the deformation of the containment, and reasonable corrections should be made to the deformation measurement results during the structural integrity test of the containment. Radiative heat exchange is a secondary environmental factor affecting the deformation of the containment structure, and it is recommended to consider the influence of this factor in order to guarantee the simulation accuracy. The containment deformation is almost the same when different thermal boundary condition application methods are used.
In the structural integrity test of the containment, the deformation of the containment is mainly caused by the test pressure and is also influenced by the ambient temperature, solar radiation and other comprehensive factors. In order to improve the deformation measurement accuracy of the test and make reasonable corrections, this paper investigates the influence law of ambient temperature, solar radiation, radiation heat exchange and different thermal boundary condition application methods on the deformation of the containment through finite element simulation analysis.The results show that the displacement of containment varies approximately sinusoidal with the ambient temperature, and lags behind the ambient temperature by about 2 h, and when the effect of solar radiation is ignored, the vertical average displacement amplitude of the dome is reduced by about 49% and the horizontal radial average displacement amplitude of the barrel is reduced by about 21%, indicating that the ambient temperature and solar radiation are the main environmental factors affecting the deformation of the containment, and reasonable corrections should be made to the deformation measurement results during the structural integrity test of the containment. Radiative heat exchange is a secondary environmental factor affecting the deformation of the containment structure, and it is recommended to consider the influence of this factor in order to guarantee the simulation accuracy. The containment deformation is almost the same when different thermal boundary condition application methods are used.
2023, 53(3): 48-52.
doi: 10.13204/j.gyjzG22082909
Abstract:
The hollow foundation is applied to the super-height prefabricated concrete tower of onshore wind power, whose stress characteristics are different from post-tensioned prestressed concrete beam structure. In this paper, a tensioning method of two symmetrical cable by stressed synchronously is proposed. At the same time, the finite element analysis software is used to simulate the different tension schemes by comparing the change of cable force and the stress response of the structure in each tension stage, and compare the maximum tensile stress value of the tower structure and the uniformity of the stress distribution. Comprehensive evaluation has carried out on each scheme to determine the a more reasonable tensioning method to guide the site construction, so as to promote the widespread application of this new type of foundation on wind power and other similar structures in future.
The hollow foundation is applied to the super-height prefabricated concrete tower of onshore wind power, whose stress characteristics are different from post-tensioned prestressed concrete beam structure. In this paper, a tensioning method of two symmetrical cable by stressed synchronously is proposed. At the same time, the finite element analysis software is used to simulate the different tension schemes by comparing the change of cable force and the stress response of the structure in each tension stage, and compare the maximum tensile stress value of the tower structure and the uniformity of the stress distribution. Comprehensive evaluation has carried out on each scheme to determine the a more reasonable tensioning method to guide the site construction, so as to promote the widespread application of this new type of foundation on wind power and other similar structures in future.
2023, 53(3): 53-61.
doi: 10.13204/j.gyjz22011409
Abstract:
Against the background of continuous expansion of the complexity theory and aesthetic intention, the space, the form and the epidermis design of many buildings were combined with digital technology, breaking through the constraints of the original paradigm and design methods, showing a trend of complexity and diversity. In particular, the formation logic and expression form of architectural forms and skins showed the complexity characteristics of nonlinear and dynamic changes. Taking the complexity of architecture as the starting point,the form and epidermis design method of complex architecture was studied and analyzed. Combined with the design practice of large-scale public buildings such as sport activity centers, the digital design process and optimization content of complex architectural forms and skins were explored taking "geometric fractal" and "emergence generation" in the complexity theory as the main design concept. In the technical method, the shaping effect of the digital design program based on the design concept on the overall forms and epidermis of buildings was emphasized, and its expression in line with the contemporary technical aesthetics was studied, and reference to the design strategy of complex architectural forms and epidermis combined with the idea of digital design was provided.
Against the background of continuous expansion of the complexity theory and aesthetic intention, the space, the form and the epidermis design of many buildings were combined with digital technology, breaking through the constraints of the original paradigm and design methods, showing a trend of complexity and diversity. In particular, the formation logic and expression form of architectural forms and skins showed the complexity characteristics of nonlinear and dynamic changes. Taking the complexity of architecture as the starting point,the form and epidermis design method of complex architecture was studied and analyzed. Combined with the design practice of large-scale public buildings such as sport activity centers, the digital design process and optimization content of complex architectural forms and skins were explored taking "geometric fractal" and "emergence generation" in the complexity theory as the main design concept. In the technical method, the shaping effect of the digital design program based on the design concept on the overall forms and epidermis of buildings was emphasized, and its expression in line with the contemporary technical aesthetics was studied, and reference to the design strategy of complex architectural forms and epidermis combined with the idea of digital design was provided.
2023, 53(3): 62-71.
doi: 10.13204/j.gyjzG21050202
Abstract:
The spatial pattern evolution characteristics of the village and small-town settlements are the important basis for optimizing the allocation of regional elements. This paper took the village and small-town settlements in Chengde central district and its surroundings as the research object, and digitized multi-source remote sensing data based on ENVI, and analyzed the spatial pattern evolution characteristics under the influence of different urban-rural relations based on GIS, which took standard deviation ellipse, nearest neighbor index (ANN) and kernel density estimation (KDE) as the spatial analysis methods. The results showed that: the spatial pattern evolution of village and small-town settlements is that from centripetal concentration to peripheral diffusion, the central position shifted and the degree of aggregation weakened under the driving forces, where the internal driving forces are topography features and river water system, the external driving forces are road system and economic development, and the comprehensive driving force is urban-rural development contradictions. The overall spatial pattern gradually changes from single center layout mode to multi center layout mode, and finally to a complex and balanced network spatial pattern which is constituted by multiple "core-periphery" mode structures.
The spatial pattern evolution characteristics of the village and small-town settlements are the important basis for optimizing the allocation of regional elements. This paper took the village and small-town settlements in Chengde central district and its surroundings as the research object, and digitized multi-source remote sensing data based on ENVI, and analyzed the spatial pattern evolution characteristics under the influence of different urban-rural relations based on GIS, which took standard deviation ellipse, nearest neighbor index (ANN) and kernel density estimation (KDE) as the spatial analysis methods. The results showed that: the spatial pattern evolution of village and small-town settlements is that from centripetal concentration to peripheral diffusion, the central position shifted and the degree of aggregation weakened under the driving forces, where the internal driving forces are topography features and river water system, the external driving forces are road system and economic development, and the comprehensive driving force is urban-rural development contradictions. The overall spatial pattern gradually changes from single center layout mode to multi center layout mode, and finally to a complex and balanced network spatial pattern which is constituted by multiple "core-periphery" mode structures.
2023, 53(3): 72-78.
doi: 10.13204/j.gyjzG21083010
Abstract:
In view of the lack of scientific assessment systems and methods in the practice of existing residence renovation, an assessment system for livable renovation effect of existing residences was constructed comprehensively by Analytic Hierarchy Process (AHP), field surveys, expert consultations etc. The system consisted of 10 first-level indicators, 28 second-level indicators and 86 third-level indicators. The weights of the indicators and the calculation methods were also discussed. Finally, the assessment system was applied to 5 demonstration renovation projects with a total of more than 500 000 m2. The operability of the system was demonstrated.
In view of the lack of scientific assessment systems and methods in the practice of existing residence renovation, an assessment system for livable renovation effect of existing residences was constructed comprehensively by Analytic Hierarchy Process (AHP), field surveys, expert consultations etc. The system consisted of 10 first-level indicators, 28 second-level indicators and 86 third-level indicators. The weights of the indicators and the calculation methods were also discussed. Finally, the assessment system was applied to 5 demonstration renovation projects with a total of more than 500 000 m2. The operability of the system was demonstrated.
2023, 53(3): 79-87,196.
doi: 10.13204/j.gyjzG21061101
Abstract:
The former site of Zhengzhou No. 2 Grinding Wheel Factory is an important part of the old industrial base in the western part of Zhengzhou. It has witnessed the rise and fall of the old industrial base. In the process of urban renewal, through the study of the historical context of Ersha, the physical environment elements in the site are retained, and the public space quality of the old industrial zone is activated by combining the memory of industrial culture, the positive surrounding community relationship is established, and Ersha is built into a new and dynamic landmark of the old urban area of Zhengzhou. This paper takes the stock system control as the research method, and starts from the three aspects of materiality, timeliness and operability, and presents the open integration and multiple rebirth between new and old buildings through the planning strategy of space complementarity, vitality shaping and multiple integration. In the planning and design, it is recommended to respect the original spatial pattern of the old industrial zone, create a distinctive public space layout of the site, reproduce the modern Bauhaus architectural style, endow the Ersha industrial heritage with new functions and significance through renovation, and also provide some reference for the study of the refining and rebirth of the industrial heritage at the spatial level.
The former site of Zhengzhou No. 2 Grinding Wheel Factory is an important part of the old industrial base in the western part of Zhengzhou. It has witnessed the rise and fall of the old industrial base. In the process of urban renewal, through the study of the historical context of Ersha, the physical environment elements in the site are retained, and the public space quality of the old industrial zone is activated by combining the memory of industrial culture, the positive surrounding community relationship is established, and Ersha is built into a new and dynamic landmark of the old urban area of Zhengzhou. This paper takes the stock system control as the research method, and starts from the three aspects of materiality, timeliness and operability, and presents the open integration and multiple rebirth between new and old buildings through the planning strategy of space complementarity, vitality shaping and multiple integration. In the planning and design, it is recommended to respect the original spatial pattern of the old industrial zone, create a distinctive public space layout of the site, reproduce the modern Bauhaus architectural style, endow the Ersha industrial heritage with new functions and significance through renovation, and also provide some reference for the study of the refining and rebirth of the industrial heritage at the spatial level.
2023, 53(3): 88-95.
doi: 10.13204/j.gyjzG22080111
Abstract:
From the perspective of value cognition, policy driving, and natural architecture, a theoretical investigation was conducted on the geographical location and ecological environment of traditional settlement space. In combination with national policies of traditional culture protection, this paper put forward the digital contiguous protection scheme of settlement, i.e., "from point to line, from line to surface, and to connected surface". This paper carried out digital modeling and innovative application of traditional residential buildings by using BIM and GIS technology approach, which promoted the revitalization of rural culture and achieved the development of settlement space culture in inheritance and the activation of settlement space culture in protection.
From the perspective of value cognition, policy driving, and natural architecture, a theoretical investigation was conducted on the geographical location and ecological environment of traditional settlement space. In combination with national policies of traditional culture protection, this paper put forward the digital contiguous protection scheme of settlement, i.e., "from point to line, from line to surface, and to connected surface". This paper carried out digital modeling and innovative application of traditional residential buildings by using BIM and GIS technology approach, which promoted the revitalization of rural culture and achieved the development of settlement space culture in inheritance and the activation of settlement space culture in protection.
2023, 53(3): 96-104.
doi: 10.13204/j.gyjzG21100101
Abstract:
In 2014, the Grand Canal was listed in the world heritage list. At the same time, China has taken the protection, inheritance and utilization of the Grand Canal as a national strategy. Looking at the whole area of the canal, the space of ancient towns along the canal is an important material carrier for the cultural inheritance and development of the canal, while the residential architectural space is the core composition of the space of ancient towns. In the process of development and evolution, the residential architectural space of Lu Canal ancient town has formed a typical spatial paradigm with canal cultural characteristics and canal historical and cultural characteristic elements, but it has not been systematically identified and summarized. Taking the residential building space of Lu Canal ancient town as the research object, through investigation and literature analysis, this paper analyzes the spatial form characteristics of courtyard buildings and the characteristics of roofs, walls, doors and windows in the architectural space from different scale levels of residential buildings, locates the basic characteristics of residential building space under the canal culture, and guides the practice of residential building space protection and repair. The research also integrates the canal culture into the residential architectural space, and puts forward the design guidance strategy of residential architectural space. It is expected to promote the research on the historical value of the space of Lu canal ancient town and eliminate the separated development state of canal culture and ancient town space.
In 2014, the Grand Canal was listed in the world heritage list. At the same time, China has taken the protection, inheritance and utilization of the Grand Canal as a national strategy. Looking at the whole area of the canal, the space of ancient towns along the canal is an important material carrier for the cultural inheritance and development of the canal, while the residential architectural space is the core composition of the space of ancient towns. In the process of development and evolution, the residential architectural space of Lu Canal ancient town has formed a typical spatial paradigm with canal cultural characteristics and canal historical and cultural characteristic elements, but it has not been systematically identified and summarized. Taking the residential building space of Lu Canal ancient town as the research object, through investigation and literature analysis, this paper analyzes the spatial form characteristics of courtyard buildings and the characteristics of roofs, walls, doors and windows in the architectural space from different scale levels of residential buildings, locates the basic characteristics of residential building space under the canal culture, and guides the practice of residential building space protection and repair. The research also integrates the canal culture into the residential architectural space, and puts forward the design guidance strategy of residential architectural space. It is expected to promote the research on the historical value of the space of Lu canal ancient town and eliminate the separated development state of canal culture and ancient town space.
2023, 53(3): 105-114.
doi: 10.13204/j.gyjzG22082104
Abstract:
Dong dwellings are the most typical traditional residential type of the minority in southwest China, and their spatial form has distinctive regional and ethnic characteristics. Taking the Dong dwellings in Sanjiang Dong Autonomous County in Liuzhou, Guangxi Province and Longhui County in Shaoyang, Hunan Province as the research objects, 27 typical Dong dwellings were selected for surveying and research, their functional distribution and spatial connection characteristics were extracted, and the topological structure analysis and operation based on space syntax were carried out. This paper analyzes the spatial topological relationship of residential buildings from the perspectives of space and culture, and calculates the core functional space through the spatial syntax "convex space model", which can be summarized into four types: the main room center type, corridor center type, courtyard center type, compound distribution type. This paper also summarizes the residents' life style represented by different core function space and the planar space characteristics of regional architecture. The combination of different plane spaces is coupled and corresponding to cultures,such as "the hall culture with respect in the center", "clan culture with house gathering", "the thought of returning to the hall with four waters" and "Huotang culture with ancestor worship", so as to reveal the cultural connotation behind the spatial combination of Dong folk houses.
Dong dwellings are the most typical traditional residential type of the minority in southwest China, and their spatial form has distinctive regional and ethnic characteristics. Taking the Dong dwellings in Sanjiang Dong Autonomous County in Liuzhou, Guangxi Province and Longhui County in Shaoyang, Hunan Province as the research objects, 27 typical Dong dwellings were selected for surveying and research, their functional distribution and spatial connection characteristics were extracted, and the topological structure analysis and operation based on space syntax were carried out. This paper analyzes the spatial topological relationship of residential buildings from the perspectives of space and culture, and calculates the core functional space through the spatial syntax "convex space model", which can be summarized into four types: the main room center type, corridor center type, courtyard center type, compound distribution type. This paper also summarizes the residents' life style represented by different core function space and the planar space characteristics of regional architecture. The combination of different plane spaces is coupled and corresponding to cultures,such as "the hall culture with respect in the center", "clan culture with house gathering", "the thought of returning to the hall with four waters" and "Huotang culture with ancestor worship", so as to reveal the cultural connotation behind the spatial combination of Dong folk houses.
2023, 53(3): 115-121.
doi: 10.13204/j.gyjzG22031112
Abstract:
Since the properties of UHPC is different from ordinary concrete, it is inappropriate to simply adopt the design methods for concrete structures and it needs to be investigated in detail. In this paper, based on strip method, the analysis model of section bending moment and curvature was established and the related calculation program was compiled by MATLAB software. By comparing with the test data, the applicability of the calculation program was verified, and the parameters were extended, including the reinforcement rate, UHPC proportion and filling part. It was found that a portion of UHPC was recommended to be configured in both the compressive and tensile zones of the cross-section at moderate reinforcement rates. In the case of high reinforcement ratio, the full-section UHPC scheme should be used as far as possible to ensure the ductility of components. The conclusion provides a reference for section optimization configuration of flexural members.
Since the properties of UHPC is different from ordinary concrete, it is inappropriate to simply adopt the design methods for concrete structures and it needs to be investigated in detail. In this paper, based on strip method, the analysis model of section bending moment and curvature was established and the related calculation program was compiled by MATLAB software. By comparing with the test data, the applicability of the calculation program was verified, and the parameters were extended, including the reinforcement rate, UHPC proportion and filling part. It was found that a portion of UHPC was recommended to be configured in both the compressive and tensile zones of the cross-section at moderate reinforcement rates. In the case of high reinforcement ratio, the full-section UHPC scheme should be used as far as possible to ensure the ductility of components. The conclusion provides a reference for section optimization configuration of flexural members.
2023, 53(3): 122-129,52.
doi: 10.13204/j.gyjzG22013101
Abstract:
In order to study the seismic performances of assembled integrated double shear walls in Prefabricated Prefinished Volumetric Construcction (PPVC), four assembled integrated double shear walls and one cast-in-place shear wall were designed to be used for low-cycle reciprocating loading experiments. The effects of grouting material strength, diameters of connecting rebars and axial compression ratios on its failure pattern, bearing capacity, ductility, stiffness,energy consumption were studied. The test results showed that grouting materials, wireropes and connecting rebars could connect the prefabricated shear walls into a whole. The failure form of the assembled integrated double shear walls was similar to that of the cast-in-place wall. X-shaped cross cracks were formed and the lower part of the wall was crushed. In the same condition, the ultimate loads of the assembled integrated double shear walls were basically equal to that of the cast-in-place walls. Increasing axial compression ratios could significantly improve the stiffness of the assembled walls. Finally, the failure mechanism of the assembled walls and the strain of bottom rebars were analyzed.
In order to study the seismic performances of assembled integrated double shear walls in Prefabricated Prefinished Volumetric Construcction (PPVC), four assembled integrated double shear walls and one cast-in-place shear wall were designed to be used for low-cycle reciprocating loading experiments. The effects of grouting material strength, diameters of connecting rebars and axial compression ratios on its failure pattern, bearing capacity, ductility, stiffness,energy consumption were studied. The test results showed that grouting materials, wireropes and connecting rebars could connect the prefabricated shear walls into a whole. The failure form of the assembled integrated double shear walls was similar to that of the cast-in-place wall. X-shaped cross cracks were formed and the lower part of the wall was crushed. In the same condition, the ultimate loads of the assembled integrated double shear walls were basically equal to that of the cast-in-place walls. Increasing axial compression ratios could significantly improve the stiffness of the assembled walls. Finally, the failure mechanism of the assembled walls and the strain of bottom rebars were analyzed.
2023, 53(3): 130-138.
doi: 10.13204/j.gyjzG22040210
Abstract:
The self-centering structure has good energy dissipation and self-centering performance, which can control the seismic response of the structure, reduce the displacement angle between the residual layers of the structure, and reduce the damage of the structure. This paper studies the performance of the new prefabricated dry connection self-centering joints, and specifically introduces the modeling process using the finite element software ABAQUS. At the same time, the cast-in-place joints are set for comparative research. The failure mechanism, seismic performance and the parameters affecting the joint performance are analyzed by finite element analysis. The research shows that the initial stiffness of the dry connection self-centering joint is equivalent to that of the cast-in-place joint, and it has strong energy dissipation capacity and self-centering performance; in the meanwhile, the joint performance is mainly affected by the initial pretension of prestressed reinforcement and the yield strength of dissipated bolt.
The self-centering structure has good energy dissipation and self-centering performance, which can control the seismic response of the structure, reduce the displacement angle between the residual layers of the structure, and reduce the damage of the structure. This paper studies the performance of the new prefabricated dry connection self-centering joints, and specifically introduces the modeling process using the finite element software ABAQUS. At the same time, the cast-in-place joints are set for comparative research. The failure mechanism, seismic performance and the parameters affecting the joint performance are analyzed by finite element analysis. The research shows that the initial stiffness of the dry connection self-centering joint is equivalent to that of the cast-in-place joint, and it has strong energy dissipation capacity and self-centering performance; in the meanwhile, the joint performance is mainly affected by the initial pretension of prestressed reinforcement and the yield strength of dissipated bolt.
2023, 53(3): 139-145,71.
doi: 10.13204/j.gyjzG22032505
Abstract:
In order to study the influence of sleeve grouting defects on the seismic performance of assembled integral concrete shear wall, three full-size shear wall specimens with increasing defect degrees and a defect-free comparative specimen were designed and produced, and the simulated static test was carried out to analyze the failure process, bearing capacity, stiffness and energy consumption capacity of the specimen. The results show that compared with the defect-free specimen, the grouting defect has little effect on the cracking load, but it will lead to different degrees of pinching of the hysteresis curve of the specimen. With the increase of defects, the yield load, peak load and energy consumption capacity of the specimen will decrease. The yield load will decrease by 3%, 8%, 15%, the peak load will decrease by 5%, 12%, 14%, and the total energy consumption will decrease by 4%, 8%, and 12%, respectively.
In order to study the influence of sleeve grouting defects on the seismic performance of assembled integral concrete shear wall, three full-size shear wall specimens with increasing defect degrees and a defect-free comparative specimen were designed and produced, and the simulated static test was carried out to analyze the failure process, bearing capacity, stiffness and energy consumption capacity of the specimen. The results show that compared with the defect-free specimen, the grouting defect has little effect on the cracking load, but it will lead to different degrees of pinching of the hysteresis curve of the specimen. With the increase of defects, the yield load, peak load and energy consumption capacity of the specimen will decrease. The yield load will decrease by 3%, 8%, 15%, the peak load will decrease by 5%, 12%, 14%, and the total energy consumption will decrease by 4%, 8%, and 12%, respectively.
2023, 53(3): 146-151,78.
doi: 10.13204/j.gyjzG22060106
Abstract:
One gymnasium of a middle school is a long-span concrete structure with chord support. By changing the structural parameters, such as the concrete strength grade, number of struts, the vertical span ratio, the static performance of the concrete girder with chord support was studied. The natural vibration characteristic of the concrete structures with chord support was analyzed by using multiple Ritz vector method. Based on this study, the impact on dynamic response performance of the concrete structures with chord support under unidirectional and three-way seismic action was studied respectively. The results show that the changes of the number of struts and the vertical span ratio have great influence on the static performance of the structure. The fundamental frequency of long span concrete structure with chord support is small and the distribution of low order frequency is dense. Under seismic action, the maximum vertical elastic displacement response of the structure appears in the middle of the span, and the displacement value meets the requirements of the code. The difference between the strut axial force and the cable force is small between the unidirectional and three-way seismic wave input.
One gymnasium of a middle school is a long-span concrete structure with chord support. By changing the structural parameters, such as the concrete strength grade, number of struts, the vertical span ratio, the static performance of the concrete girder with chord support was studied. The natural vibration characteristic of the concrete structures with chord support was analyzed by using multiple Ritz vector method. Based on this study, the impact on dynamic response performance of the concrete structures with chord support under unidirectional and three-way seismic action was studied respectively. The results show that the changes of the number of struts and the vertical span ratio have great influence on the static performance of the structure. The fundamental frequency of long span concrete structure with chord support is small and the distribution of low order frequency is dense. Under seismic action, the maximum vertical elastic displacement response of the structure appears in the middle of the span, and the displacement value meets the requirements of the code. The difference between the strut axial force and the cable force is small between the unidirectional and three-way seismic wave input.
2023, 53(3): 152-157,166.
doi: 10.13204/j.gyjzG21013001
Abstract:
In this paper, the bearing capacity of joints under pre-loading of 3 groups of T-shaped joints reinforced with external stiffeners was investigated. According to the ratio of the diameter of the brace and the chord, it was divided into three groups (β=0.25、0.50 and 0.73) for comparison. The specimen dimension design, the loading process of the pre-loading, the loading system, the welding work during the loading process and the failure mode were introduced in detail. There were two typical failure modes: node failure and out-of-plane tilt. The experimental results showed that when β=0.25, the failure mode of the joint was the yield of the stiffener, and when β=0.5 or 0.73, the joint appeared out-of-plane inclination in different degrees. Therefore, the out-of-plane tilt was the most important failure mode for T-joints under axial load. The welding reinforcement sequence had an important influence on the temperature-induced deformation development of T-shaped circular steel tubes under load. The vertical displacement of the brace increased and the force of the jack decreased when the welding heat was applied, and the vertical displacement of the brace rebounded after the welding cooling, and the force of the jack load sensor increased. The influence of initial load on the bearing capacity of joint was different with different factors. When β=0.25, with the increase of the initial load, the ultimate bearing capacity came later and the total displacement of the structure increased, but the magnitude of the bearing capacity did not change obviously from 250.7 kN to 250.9 kN. When β=0.5, with the increase of initial load, the carrying capacity decreased by 73% from 350 kN to 324.6 kN and joint stiffness also decreased. When the value was 0.73, due to the large out-plane inclination of T3-60, the experiment was stopped ahead of time, but it could be seen that with the increase of the initial load, the ultimate bearing capacity increased by 13.3% from 499.7 kN to 566.2 kN, and the stiffness of the joint did not change obviously.
In this paper, the bearing capacity of joints under pre-loading of 3 groups of T-shaped joints reinforced with external stiffeners was investigated. According to the ratio of the diameter of the brace and the chord, it was divided into three groups (β=0.25、0.50 and 0.73) for comparison. The specimen dimension design, the loading process of the pre-loading, the loading system, the welding work during the loading process and the failure mode were introduced in detail. There were two typical failure modes: node failure and out-of-plane tilt. The experimental results showed that when β=0.25, the failure mode of the joint was the yield of the stiffener, and when β=0.5 or 0.73, the joint appeared out-of-plane inclination in different degrees. Therefore, the out-of-plane tilt was the most important failure mode for T-joints under axial load. The welding reinforcement sequence had an important influence on the temperature-induced deformation development of T-shaped circular steel tubes under load. The vertical displacement of the brace increased and the force of the jack decreased when the welding heat was applied, and the vertical displacement of the brace rebounded after the welding cooling, and the force of the jack load sensor increased. The influence of initial load on the bearing capacity of joint was different with different factors. When β=0.25, with the increase of the initial load, the ultimate bearing capacity came later and the total displacement of the structure increased, but the magnitude of the bearing capacity did not change obviously from 250.7 kN to 250.9 kN. When β=0.5, with the increase of initial load, the carrying capacity decreased by 73% from 350 kN to 324.6 kN and joint stiffness also decreased. When the value was 0.73, due to the large out-plane inclination of T3-60, the experiment was stopped ahead of time, but it could be seen that with the increase of the initial load, the ultimate bearing capacity increased by 13.3% from 499.7 kN to 566.2 kN, and the stiffness of the joint did not change obviously.
2023, 53(3): 158-166.
doi: 10.13204/j.gyjzG22011606
Abstract:
In order to study the bearing performance of stainless steel core plate (SSCP) floor considering brazing residual stress (BRS) distribution, the BRS in 25 single-unit specimens of SSCP were determined by hole-drilling method and X-ray diffraction method, and the simplified predictive model for the BRS distributions in SSCP was proposed. The proposed simplified model, as the initial defect, was introduced into the finite element model (FEM) of the three-point bending test of the SSCP floor, and the reliability of the simplified distribution model is verified by comparing the calculation results of the FEM considering the BRS distribution and without BRS distribution with the test results of the SSCP floor, and the FEM was parametrically analyzed. The test and research results show that the recommended peak value of tensile BRS for the simplified predictive model is 0.6σ0.2. The FEM considering the BRS distribution is able to accurately simulate the bearing performance of the SSCP floor. Calculated shear stiffness of the FEM considering BRS distribution is more accurate.
In order to study the bearing performance of stainless steel core plate (SSCP) floor considering brazing residual stress (BRS) distribution, the BRS in 25 single-unit specimens of SSCP were determined by hole-drilling method and X-ray diffraction method, and the simplified predictive model for the BRS distributions in SSCP was proposed. The proposed simplified model, as the initial defect, was introduced into the finite element model (FEM) of the three-point bending test of the SSCP floor, and the reliability of the simplified distribution model is verified by comparing the calculation results of the FEM considering the BRS distribution and without BRS distribution with the test results of the SSCP floor, and the FEM was parametrically analyzed. The test and research results show that the recommended peak value of tensile BRS for the simplified predictive model is 0.6σ0.2. The FEM considering the BRS distribution is able to accurately simulate the bearing performance of the SSCP floor. Calculated shear stiffness of the FEM considering BRS distribution is more accurate.
2023, 53(3): 167-172,179.
doi: 10.13204/j.gyjzG21012404
Abstract:
Based on the deflection of structural components occurring at the lateral deformation of moment frames, the author proposed a new lateral resistance RBF (R-Brace Frame) system, which is capable of effectively limiting the drift of tall buildings. To evaluate internal force distribution and deformation of the RBF system, FEM program SAP2000 was used. Pushover method and capacity spectrum method were used to assess yielding mechanism of seismic performance of the structure under rare earthquake. The findings revealed that the RBF system had a major impact on improving the structure's lateral stiffness. The stiffness deterioration of the RBF system is controllable, and the seismic ductility of the structure can be guaranteed by the RBF system. The RBF system would not alter the direction of propagation of the vertical force of the initial structure. It is ideal for existing buildings for seismic retrofitting.
Based on the deflection of structural components occurring at the lateral deformation of moment frames, the author proposed a new lateral resistance RBF (R-Brace Frame) system, which is capable of effectively limiting the drift of tall buildings. To evaluate internal force distribution and deformation of the RBF system, FEM program SAP2000 was used. Pushover method and capacity spectrum method were used to assess yielding mechanism of seismic performance of the structure under rare earthquake. The findings revealed that the RBF system had a major impact on improving the structure's lateral stiffness. The stiffness deterioration of the RBF system is controllable, and the seismic ductility of the structure can be guaranteed by the RBF system. The RBF system would not alter the direction of propagation of the vertical force of the initial structure. It is ideal for existing buildings for seismic retrofitting.
2023, 53(3): 173-179.
doi: 10.12304/j.gyjzG22061409
Abstract:
Taking the tunnel construction near the Gaojiawan fault fracture zone as the engineering background, the shear instability mechanism of the outburst-prevention rock mass at the working face in the deep and large water-rich fault fracture zone tunnel was studied by theoretical analysis and numerical simulations, and the safety thickness of the outburst-prevention was analyzed. The results showed that the essence of water and mud inrush in tunnels near the water rich fault fracture zone was that construction disturbance leaded to the change of the surrounding rock stress fields and seepage fields in the fault fracture zone. Under the water and force coupling effect, the insufficient outburst-prevention thickness of the rock mass at the at the working face in tunnels caused shear instability; the changes of instability evaluation indexes such as fault zone water pressure, water inrush volumes at working faces of tunnels, horizontal displacement and plastic zone areas all reflected obvious characteristics of "stability—development—instability" in the process of tunneling through the fault fracture zone, which were also basically consistent with the development process of water and mud inrush in actual construction. Integrating various instability evaluation indexes, it was determined that the critical safety thickness of the tunnel for outburst prevention was 0.95 times the effective diameter of the tunnel. Compared with the width of the fault fracture zone, the burial depth had a more significant impact on the outburst-prevention of tunnels in the deep and large water-rich fault fracture zone. Simultaneously, with the increase of the tunnel burial depth, the influence of the width of the fault fracture zone on the safety of outburst prevention gradually increased.
Taking the tunnel construction near the Gaojiawan fault fracture zone as the engineering background, the shear instability mechanism of the outburst-prevention rock mass at the working face in the deep and large water-rich fault fracture zone tunnel was studied by theoretical analysis and numerical simulations, and the safety thickness of the outburst-prevention was analyzed. The results showed that the essence of water and mud inrush in tunnels near the water rich fault fracture zone was that construction disturbance leaded to the change of the surrounding rock stress fields and seepage fields in the fault fracture zone. Under the water and force coupling effect, the insufficient outburst-prevention thickness of the rock mass at the at the working face in tunnels caused shear instability; the changes of instability evaluation indexes such as fault zone water pressure, water inrush volumes at working faces of tunnels, horizontal displacement and plastic zone areas all reflected obvious characteristics of "stability—development—instability" in the process of tunneling through the fault fracture zone, which were also basically consistent with the development process of water and mud inrush in actual construction. Integrating various instability evaluation indexes, it was determined that the critical safety thickness of the tunnel for outburst prevention was 0.95 times the effective diameter of the tunnel. Compared with the width of the fault fracture zone, the burial depth had a more significant impact on the outburst-prevention of tunnels in the deep and large water-rich fault fracture zone. Simultaneously, with the increase of the tunnel burial depth, the influence of the width of the fault fracture zone on the safety of outburst prevention gradually increased.
2023, 53(3): 180-187.
doi: 10.13204/j.gyjzG22011905
Abstract:
As one of the important foundation types of mooring systems in marine structures, rigid anchor piles often bear oblique upward pulling loads, and the mechanism of oblique uplift resistance is more complex than that of flexible piles. Through numerical simulations and theoretical analysis, the influence of loading modes and pile-soil interface friction coefficients on the oblique uplift capacity of anchor piles was studied. Based on the finite element numerical model, the failure envelope surfaces of anchor piles in different loading modes and friction coefficients were obtained, and it was found that the oblique uplift capacity of anchor piles was significantly influenced by loading modes. Due to the limitation of Mohr-Coulomb Constitutive Model, it was difficult for numerical models to accurately simulate the vertical uplift properties of anchor piles with rough appearances. With the increase of friction coefficients, the vertical uplift capacity of anchor piles increased because of the development of fracture toward soil around piles. The horizontal bearing capacity of anchor piles was relatively accurate calculated by the S-shaped distribution hypothesis of soil resistance. Finally, an envelope model of rigid anchor piles was constructed considering the friction coefficients of pile-soil interfaces.
As one of the important foundation types of mooring systems in marine structures, rigid anchor piles often bear oblique upward pulling loads, and the mechanism of oblique uplift resistance is more complex than that of flexible piles. Through numerical simulations and theoretical analysis, the influence of loading modes and pile-soil interface friction coefficients on the oblique uplift capacity of anchor piles was studied. Based on the finite element numerical model, the failure envelope surfaces of anchor piles in different loading modes and friction coefficients were obtained, and it was found that the oblique uplift capacity of anchor piles was significantly influenced by loading modes. Due to the limitation of Mohr-Coulomb Constitutive Model, it was difficult for numerical models to accurately simulate the vertical uplift properties of anchor piles with rough appearances. With the increase of friction coefficients, the vertical uplift capacity of anchor piles increased because of the development of fracture toward soil around piles. The horizontal bearing capacity of anchor piles was relatively accurate calculated by the S-shaped distribution hypothesis of soil resistance. Finally, an envelope model of rigid anchor piles was constructed considering the friction coefficients of pile-soil interfaces.
2023, 53(3): 188-196.
doi: 10.13204/j.gyjzG22011403
Abstract:
Some special geotechnical problems will be encountered during the process of deep foundation excavation in inclined interbedding strata close to rivers, but up to now the related study has still been insufficient. Taking the deep foundation excavation project of a sewage-treatment plant in Anning District of Lanzhou as an example, through in-situ monitoring and numerical calculations, the differences of groundwater seepage and surrounding subsidence of ground, during deep ercavation supported with piles and anchor bars combined with dewatering with dewatering wells, between inclined and horizontal interbedding were analyzed. The results showed that in the process of dewatering during foundation excavation, the total water level curve in interbedding strata increased in a stepped pattern, and the total water head was about 2 m lower than that in horizontal rock strata. During excavation, the vertical displacement of pile tops and ground subsidence adjacent to the trench in inclined interbedding were significantly greater than those in horizontal interbedding, and the subsidence difference between the two adjacent to buildings was greater. With the gradually exposure of inclined interbedding strata, the groundwater bypassed recharge, and severe water seepage was in the local areas at the bottom of the trench, which increased the difficulty of foundation excavation. Therefore, how to reasonably design and optimize the water-stop and deformation control scheme for foundation excavation in inclined interbedding remaind to be systematically studied.
Some special geotechnical problems will be encountered during the process of deep foundation excavation in inclined interbedding strata close to rivers, but up to now the related study has still been insufficient. Taking the deep foundation excavation project of a sewage-treatment plant in Anning District of Lanzhou as an example, through in-situ monitoring and numerical calculations, the differences of groundwater seepage and surrounding subsidence of ground, during deep ercavation supported with piles and anchor bars combined with dewatering with dewatering wells, between inclined and horizontal interbedding were analyzed. The results showed that in the process of dewatering during foundation excavation, the total water level curve in interbedding strata increased in a stepped pattern, and the total water head was about 2 m lower than that in horizontal rock strata. During excavation, the vertical displacement of pile tops and ground subsidence adjacent to the trench in inclined interbedding were significantly greater than those in horizontal interbedding, and the subsidence difference between the two adjacent to buildings was greater. With the gradually exposure of inclined interbedding strata, the groundwater bypassed recharge, and severe water seepage was in the local areas at the bottom of the trench, which increased the difficulty of foundation excavation. Therefore, how to reasonably design and optimize the water-stop and deformation control scheme for foundation excavation in inclined interbedding remaind to be systematically studied.
2023, 53(3): 197-200,95.
doi: 10.13204/j.gyjzG21122601
Abstract:
A series of undrained shear tests with different effective confining pressures were conducted to study the effect of the gas content on pore pressure variation and strain isolines of remolded fine aerated soil based on the microporous adsorption properties of zeolite. Before the axial strain reached 5%, the pore pressure of saturated soil developed faster than that of aerated fine-grained soil, while the axial strain exceeded 5%, the pore pressure of aerated soil developed faster than that of saturated soil. In the same strain, the pore pressure in aerated soil was larger and the corresponding shear strength was smaller. In different contents of gas, the slope of the critical state line was a constant, it was 1.25. The strain isolines along the effective stress paths of soil with different contents of gas under different confining pressures could be regarded as straight lines, and their slopes increased gradually with the increase of strains and finally coincided with the critical state lines.
A series of undrained shear tests with different effective confining pressures were conducted to study the effect of the gas content on pore pressure variation and strain isolines of remolded fine aerated soil based on the microporous adsorption properties of zeolite. Before the axial strain reached 5%, the pore pressure of saturated soil developed faster than that of aerated fine-grained soil, while the axial strain exceeded 5%, the pore pressure of aerated soil developed faster than that of saturated soil. In the same strain, the pore pressure in aerated soil was larger and the corresponding shear strength was smaller. In different contents of gas, the slope of the critical state line was a constant, it was 1.25. The strain isolines along the effective stress paths of soil with different contents of gas under different confining pressures could be regarded as straight lines, and their slopes increased gradually with the increase of strains and finally coincided with the critical state lines.
2023, 53(3): 201-207.
doi: 10.13204/j.gyjzG22070305
Abstract:
In order to explore the reinforcement non-uniform corrosion under the influence of the spatial distribution characteristics of surface chloride ion concentration, a coupling model of mass transport and reinforcement electrochemical corrosion was constructed in this paper. Based on the surface chloride concentration data of concrete in real marine environment, the free chloride concentration distribution, current density distribution and corrosion form of internal reinforcement were analyzed. The results show that the distribution characteristics of surface chloride ion concentration of reinforcement and concrete are basically the same in the longitudinal direction, but the migration of chloride ion in the circumferential direction makes the development law of surface chloride ion concentration of reinforcement and concrete different. In circumferential direction, micro cell corrosion of reinforcement starts from the side with high surface chloride ion concentration of the concrete and develops into uniform corrosion on the whole section.
In order to explore the reinforcement non-uniform corrosion under the influence of the spatial distribution characteristics of surface chloride ion concentration, a coupling model of mass transport and reinforcement electrochemical corrosion was constructed in this paper. Based on the surface chloride concentration data of concrete in real marine environment, the free chloride concentration distribution, current density distribution and corrosion form of internal reinforcement were analyzed. The results show that the distribution characteristics of surface chloride ion concentration of reinforcement and concrete are basically the same in the longitudinal direction, but the migration of chloride ion in the circumferential direction makes the development law of surface chloride ion concentration of reinforcement and concrete different. In circumferential direction, micro cell corrosion of reinforcement starts from the side with high surface chloride ion concentration of the concrete and develops into uniform corrosion on the whole section.
2023, 53(3): 208-215.
doi: 10.13204/j.gyjzG22052414
Abstract:
The corn husk fibers with different mass fraction and expanded polystyrene (EPS) particles were mixed and added to the cement matrix to study their effects on the density, water absorption, compressive strength, flexural strength, splitting tensile strength and frost resistance of the composites. The results showed that the higher the content of corn skin plant fiber, the lower the density and the higher the water absorption of EPS cement-based composites; the compressive strength decreases with the increase of fiber content and EPS content, and the maximum compressive strength is 2.2 MPa and the minimum is 0.8 MPa; the flexural strength increases first and then decreases with the increase of fiber content, and when the fiber content is 3%, EPS content is 1.3%, the maximum flexural strength is 1.2 MPa; the splitting tensile strength increases with the increase of fiber content and decreases with the increase of EPS content, and when the fiber content is 3%, EPS content is 1.1%, and the highest splitting tensile strength is 1.1 MPa. What’s more, the addition of corn bran fiber can effectively reduce the mass loss and strength loss of the composite and improve its frost resistance.
The corn husk fibers with different mass fraction and expanded polystyrene (EPS) particles were mixed and added to the cement matrix to study their effects on the density, water absorption, compressive strength, flexural strength, splitting tensile strength and frost resistance of the composites. The results showed that the higher the content of corn skin plant fiber, the lower the density and the higher the water absorption of EPS cement-based composites; the compressive strength decreases with the increase of fiber content and EPS content, and the maximum compressive strength is 2.2 MPa and the minimum is 0.8 MPa; the flexural strength increases first and then decreases with the increase of fiber content, and when the fiber content is 3%, EPS content is 1.3%, the maximum flexural strength is 1.2 MPa; the splitting tensile strength increases with the increase of fiber content and decreases with the increase of EPS content, and when the fiber content is 3%, EPS content is 1.1%, and the highest splitting tensile strength is 1.1 MPa. What’s more, the addition of corn bran fiber can effectively reduce the mass loss and strength loss of the composite and improve its frost resistance.
