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2025 Vol. 55, No. 8
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2025, 55(8): 1-6.
doi: 10.3724/j.gyjzG25060604
Abstract:
Welded sections dominate in the steel structures of civil buildings in China, while the proportion of rolled sections is relatively low, far below the application level of developed countries. In order to promote the large-scale application of rolled sections in the field of civil construction, this paper compared the process and performance differences between rolled sections and welded sections, analyzed the key constraining factors hindering the large-scale application of rolled sections in China’s civil construction field, and proposed a path for the large-scale application of rolled sections based on high-efficiency & high-performance standardized steel structure systems and key application technologies. Based on this implementation path, the large-scale application of rolled sections in China’s civil construction field can be effectively promoted, contributing to the national strategic goal of "carbon neutrality and carbon peak".
Welded sections dominate in the steel structures of civil buildings in China, while the proportion of rolled sections is relatively low, far below the application level of developed countries. In order to promote the large-scale application of rolled sections in the field of civil construction, this paper compared the process and performance differences between rolled sections and welded sections, analyzed the key constraining factors hindering the large-scale application of rolled sections in China’s civil construction field, and proposed a path for the large-scale application of rolled sections based on high-efficiency & high-performance standardized steel structure systems and key application technologies. Based on this implementation path, the large-scale application of rolled sections in China’s civil construction field can be effectively promoted, contributing to the national strategic goal of "carbon neutrality and carbon peak".
2025, 55(8): 7-13.
doi: 10.3724/j.gyjzG25060605
Abstract:
The promotion and application of high-efficiency & high-performance standardized steel structure is an important component of the green transformation and high-quality development of the construction industry, and is one of the key ways to promote the large-scale application of rolled sections. To promote the large-scale application of rolled sections and systematically evaluate high-efficiency & high-performance standardized steel structure, this paper constructed an evaluation index system for high-efficiency & high-performance standardized steel structure and conducted a preliminary evaluation on actual projects. The evaluation results show that the evaluation index system constructed in this paper can accurately reflect and guide the engineering practice of high-efficiency & high-performance standardized steel structure, thereby promoting the large-scale application of the rolled sections.
The promotion and application of high-efficiency & high-performance standardized steel structure is an important component of the green transformation and high-quality development of the construction industry, and is one of the key ways to promote the large-scale application of rolled sections. To promote the large-scale application of rolled sections and systematically evaluate high-efficiency & high-performance standardized steel structure, this paper constructed an evaluation index system for high-efficiency & high-performance standardized steel structure and conducted a preliminary evaluation on actual projects. The evaluation results show that the evaluation index system constructed in this paper can accurately reflect and guide the engineering practice of high-efficiency & high-performance standardized steel structure, thereby promoting the large-scale application of the rolled sections.
2025, 55(8): 14-22.
doi: 10.3724/j.gyjzG25060607
Abstract:
Hot-rolled H-shape steel has multiple advantages such as high dimensional accuracy, good mechanical properties, and no need for welding, making them suitable prefabricated profiles for use in various steel structural components. However, the proportion of hot-rolled H-shaped steel used in domestic civil building steel structures is not high. To understand the current application status and problems of hot-rolled H-shaped steel in civil building steel structures, a survey was conducted on 31 representative design units in China, collecting design information on more than 200 steel structure projects, including basic project information, component sections, design methods, and the application of hot-rolled H-shaped steel. Secondly, the opinions of designers on the application of hot-rolled Hshaped steel were investigated and summarized, and multiple solutions, including optimizing and adjusting the specifications of hot-rolled H-shaped steel, were proposed. Finally, the proportion of various section types of steel structural components and the commonly used dimensions of H shape steel sections were statistically analyzed, laying the foundation for the development of applicable hot-rolled H-shape steel specifications.
Hot-rolled H-shape steel has multiple advantages such as high dimensional accuracy, good mechanical properties, and no need for welding, making them suitable prefabricated profiles for use in various steel structural components. However, the proportion of hot-rolled H-shaped steel used in domestic civil building steel structures is not high. To understand the current application status and problems of hot-rolled H-shaped steel in civil building steel structures, a survey was conducted on 31 representative design units in China, collecting design information on more than 200 steel structure projects, including basic project information, component sections, design methods, and the application of hot-rolled H-shaped steel. Secondly, the opinions of designers on the application of hot-rolled Hshaped steel were investigated and summarized, and multiple solutions, including optimizing and adjusting the specifications of hot-rolled H-shaped steel, were proposed. Finally, the proportion of various section types of steel structural components and the commonly used dimensions of H shape steel sections were statistically analyzed, laying the foundation for the development of applicable hot-rolled H-shape steel specifications.
2025, 55(8): 23-31.
doi: 10.3724/j.gyjzG25060608
Abstract:
To promote the use of hot-rolled H-beam steel products in civil buildings, the design principles of hot-rolled H-beam are analyzed and summarized by the Four Cardinal Principles: safety, reasonability, economy, and convenience. A product system that suits China’s conditions should be established accordingly. According to the analysis of hot-rolled H-beam product specifications systems in Europe, America, and Japan, combined with the actual situation in China and the development of the construction industry, some suggestions are proposed for the development direction of hot-rolled H-beam products in China. It is suggested that the hot-rolled H-section steel for civil construction should be subdivided according to the type of components, and the existing product specifications and subdivisions should be optimized. At the same time, the supporting detailing and the standardized set of application systems should be researched and developed. For beams, improving economy and convenience should be the main research direction to guide the standardization of steel structure design. For compression members, safety and rationality should be highly concerned, which should be used in their appropriate scope. The apposite scope could be extended by inventing new products, derivative products, and new structural systems.
To promote the use of hot-rolled H-beam steel products in civil buildings, the design principles of hot-rolled H-beam are analyzed and summarized by the Four Cardinal Principles: safety, reasonability, economy, and convenience. A product system that suits China’s conditions should be established accordingly. According to the analysis of hot-rolled H-beam product specifications systems in Europe, America, and Japan, combined with the actual situation in China and the development of the construction industry, some suggestions are proposed for the development direction of hot-rolled H-beam products in China. It is suggested that the hot-rolled H-section steel for civil construction should be subdivided according to the type of components, and the existing product specifications and subdivisions should be optimized. At the same time, the supporting detailing and the standardized set of application systems should be researched and developed. For beams, improving economy and convenience should be the main research direction to guide the standardization of steel structure design. For compression members, safety and rationality should be highly concerned, which should be used in their appropriate scope. The apposite scope could be extended by inventing new products, derivative products, and new structural systems.
2025, 55(8): 32-38.
doi: 10.3724/j.gyjzG25061704
Abstract:
Hot-rolled heavy H-section steel is defined as hot-rolled H-section steel with a weight per meter not less than 3000 N or a flange thickness not less than 40 mm. This paper reviews the research findings on material properties and residual stress of hot-rolled heavy H-section steel, conducts a comparative analysis of experimental data in accordance with current Chinese codes, and provides some design and application recommendations. The material properties of hot-rolled heavy H-section steel exhibit variability at different cross-sectional locations, and fluctuations in material properties are observed along the thickness direction at the same cross-sectional position. The material property data obtained from sampling based on current Chinese codes can effectively reflect the average material properties of the cross-section of hot-rolled heavy H-section steel. The residual stress distribution in hot-rolled heavy H-section steel differs from that of ordinary hot-rolled H-section steel, showing parabolic or multi-curve patterns in the flange and web regions, with significant variations in residual stress values along the thickness direction at the same location. The residual stress distribution model for hot-rolled H-section steel used in current Chinese codes to determine column stability curves exhibits discrepancies compared to the actual residual stress distribution of hot-rolled heavy H-section steel obtained from the existing research, which may lead to conservative design results.
Hot-rolled heavy H-section steel is defined as hot-rolled H-section steel with a weight per meter not less than 3000 N or a flange thickness not less than 40 mm. This paper reviews the research findings on material properties and residual stress of hot-rolled heavy H-section steel, conducts a comparative analysis of experimental data in accordance with current Chinese codes, and provides some design and application recommendations. The material properties of hot-rolled heavy H-section steel exhibit variability at different cross-sectional locations, and fluctuations in material properties are observed along the thickness direction at the same cross-sectional position. The material property data obtained from sampling based on current Chinese codes can effectively reflect the average material properties of the cross-section of hot-rolled heavy H-section steel. The residual stress distribution in hot-rolled heavy H-section steel differs from that of ordinary hot-rolled H-section steel, showing parabolic or multi-curve patterns in the flange and web regions, with significant variations in residual stress values along the thickness direction at the same location. The residual stress distribution model for hot-rolled H-section steel used in current Chinese codes to determine column stability curves exhibits discrepancies compared to the actual residual stress distribution of hot-rolled heavy H-section steel obtained from the existing research, which may lead to conservative design results.
2025, 55(8): 39-45.
doi: 10.3724/j.gyjzG25060606
Abstract:
Profile steel components, characterized by their high degree of standardization and construction convenience, are considered green and high-efficiency & high-performance steel materials. However, the current processing methods have problems such as labor intensity and low efficiency. The key to realizing the digital manufacturing of profile steel components lies in the combination of advanced manufacturing processes, production control systems, and intelligent equipment. Based on three-dimensional model-driven and visual sensing technologies, this paper developed digital cutting, welding, surface cleaning, spraying processes, and advanced intelligent equipment for profile steel components. A cloud virtual system for manufacturing materials of steel structures was developed to connect the business, finance, and the Internet of Things, realizing the digital management of the entire process from placing orders for steel materials to blanking in the workshop. A manufacturing execution system for the production line of profile steel components was established to collect data of processing equipment in real time and conduct visual monitoring of the processing status of components. Finally, the digital manufacturing of profile steel components and the production line were verified through engineering applications, providing a reference for industry peers to carry out related research and application work.
Profile steel components, characterized by their high degree of standardization and construction convenience, are considered green and high-efficiency & high-performance steel materials. However, the current processing methods have problems such as labor intensity and low efficiency. The key to realizing the digital manufacturing of profile steel components lies in the combination of advanced manufacturing processes, production control systems, and intelligent equipment. Based on three-dimensional model-driven and visual sensing technologies, this paper developed digital cutting, welding, surface cleaning, spraying processes, and advanced intelligent equipment for profile steel components. A cloud virtual system for manufacturing materials of steel structures was developed to connect the business, finance, and the Internet of Things, realizing the digital management of the entire process from placing orders for steel materials to blanking in the workshop. A manufacturing execution system for the production line of profile steel components was established to collect data of processing equipment in real time and conduct visual monitoring of the processing status of components. Finally, the digital manufacturing of profile steel components and the production line were verified through engineering applications, providing a reference for industry peers to carry out related research and application work.
2025, 55(8): 46-52.
doi: 10.3724/j.gyjzG25060611
Abstract:
At present, the production processes of square and rectangular steel tubes mainly involve welding four steel plates together or cold forming. The welded square and rectangular tube components have problems such as large amounts of longitudinal and electroslag welding work and suboptimal mechanical performance at beam-column joints. The cold-formed square and rectangular tube components have issues like cold work hardening at the four corners of the cross-section and poor weldability at the cold-formed parts. Additionally, the above production processes of square and rectangular tube components are complex and not suitable for high-efficiency intelligent manufacturing. Focusing on intelligent manufacturing of steel structures, a production process for double-welded seam hot-rolled square and rectangular tube components is proposed. The square and rectangular tube components are fabricated by welding two equal-thickness hot-rolled channel steels together, with separate partition plates and other processes, and are manufactured efficiently using intelligent manufacturing methods. This paper mainly introduces the technical requirements of the square and rectangular tube profiles, the design of structural nodes, and the intelligent manufacturing process, providing guidance for the development of such components.
At present, the production processes of square and rectangular steel tubes mainly involve welding four steel plates together or cold forming. The welded square and rectangular tube components have problems such as large amounts of longitudinal and electroslag welding work and suboptimal mechanical performance at beam-column joints. The cold-formed square and rectangular tube components have issues like cold work hardening at the four corners of the cross-section and poor weldability at the cold-formed parts. Additionally, the above production processes of square and rectangular tube components are complex and not suitable for high-efficiency intelligent manufacturing. Focusing on intelligent manufacturing of steel structures, a production process for double-welded seam hot-rolled square and rectangular tube components is proposed. The square and rectangular tube components are fabricated by welding two equal-thickness hot-rolled channel steels together, with separate partition plates and other processes, and are manufactured efficiently using intelligent manufacturing methods. This paper mainly introduces the technical requirements of the square and rectangular tube profiles, the design of structural nodes, and the intelligent manufacturing process, providing guidance for the development of such components.
2025, 55(8): 53-59.
doi: 10.3724/j.gyjzG25060610
Abstract:
To investigate the influence of the V-Ti composition system on the material strength grade and quality grade, deformation thermal simulation tests were conducted to study the microstructural transformation law. Combined with actual production trials, in this paper, field trials and performance testing were carried out on hot-rolled H-section steel of typical column member specifications for building steel structures. The results indicated that when producing H400×400 hot-rolled H-section using a V-Ti alloy system, with a flange reduction of 60% in the universal stand, a rolling cooling rate of 0.5℃/s to 1℃/s, and rolling temperature control at 940～960℃, the product could achieve a strength grade of Q420 and a low-temperature ductile-to-brittle transition temperature as low as -50℃. Additionally, considering practical production cost control, synchronously producing small batches of hot-rolled H-section with the same steel grade (Q355 to Q420) but different quality levels (B to E grades) demonstrates economic feasibility, providing technical support for efficient production of hot-rolled H-section steel and material selection for standard components.
To investigate the influence of the V-Ti composition system on the material strength grade and quality grade, deformation thermal simulation tests were conducted to study the microstructural transformation law. Combined with actual production trials, in this paper, field trials and performance testing were carried out on hot-rolled H-section steel of typical column member specifications for building steel structures. The results indicated that when producing H400×400 hot-rolled H-section using a V-Ti alloy system, with a flange reduction of 60% in the universal stand, a rolling cooling rate of 0.5℃/s to 1℃/s, and rolling temperature control at 940～960℃, the product could achieve a strength grade of Q420 and a low-temperature ductile-to-brittle transition temperature as low as -50℃. Additionally, considering practical production cost control, synchronously producing small batches of hot-rolled H-section with the same steel grade (Q355 to Q420) but different quality levels (B to E grades) demonstrates economic feasibility, providing technical support for efficient production of hot-rolled H-section steel and material selection for standard components.
2025, 55(8): 60-68.
doi: 10.3724/j.gyjzG25080507
Abstract:
In view of the current problems existing in the steel structure building industry, such as low industrialization degree, low utilization rate of components and profiles, and low level of production automation, this paper took the steel frame structure system based on hollow tubular material columns as the object and conducted research from two aspects: the section specification sequence of hollow pipes and the standardized design of the structure. The requirements of civil buildings for steel component dimensions and structural cost-effectiveness were analyzed, and the bottlenecks and countermeasures for applying hollow tubular materials in civil buildings were clarified. Key technologies for the standardized design of steel frame systems, components, and connection nodes were developed to achieve effective integration of design and construction, thereby enhancing the overall project efficiency. The research outcomes were demonstrated in a parking building project. Comparative analysis with existing structural systems showed that the demonstration project achieved a 97.81% utilization rate of standardized components, a 78.5% node standardization level, a 208.3% increase in construction efficiency, and a 53.1% reduction in comprehensive energy consumption, demonstrating significant exemplary effectiveness.
In view of the current problems existing in the steel structure building industry, such as low industrialization degree, low utilization rate of components and profiles, and low level of production automation, this paper took the steel frame structure system based on hollow tubular material columns as the object and conducted research from two aspects: the section specification sequence of hollow pipes and the standardized design of the structure. The requirements of civil buildings for steel component dimensions and structural cost-effectiveness were analyzed, and the bottlenecks and countermeasures for applying hollow tubular materials in civil buildings were clarified. Key technologies for the standardized design of steel frame systems, components, and connection nodes were developed to achieve effective integration of design and construction, thereby enhancing the overall project efficiency. The research outcomes were demonstrated in a parking building project. Comparative analysis with existing structural systems showed that the demonstration project achieved a 97.81% utilization rate of standardized components, a 78.5% node standardization level, a 208.3% increase in construction efficiency, and a 53.1% reduction in comprehensive energy consumption, demonstrating significant exemplary effectiveness.
2025, 55(8): 69-75.
doi: 10.3724/j.gyjzG25072705
Abstract:
As an industrialized steel profile, hot-rolled H-shaped steel plays a key role in promoting construction industrialization and sustainable development through its widespread application. This paper takes the steel frame structure of a school building as its research object and conducts a comparative analysis with the traditional welded box-column frame system from five aspects: seismic performance, joint reliability, standardization level, construction efficiency, and overall energy consumption. The study explores the structural safety applicability and energy-saving effects of hot-rolled H-shaped steel in civil buildings, providing both theoretical support and practical references for its engineering applications.
As an industrialized steel profile, hot-rolled H-shaped steel plays a key role in promoting construction industrialization and sustainable development through its widespread application. This paper takes the steel frame structure of a school building as its research object and conducts a comparative analysis with the traditional welded box-column frame system from five aspects: seismic performance, joint reliability, standardization level, construction efficiency, and overall energy consumption. The study explores the structural safety applicability and energy-saving effects of hot-rolled H-shaped steel in civil buildings, providing both theoretical support and practical references for its engineering applications.
2025, 55(8): 76-83.
doi: 10.3724/j.gyjzG25082905
Abstract:
The installation of long-span fully bolted steel structures is carried out using a multi-stage connection process. If components are manufactured solely based on nominal dimensions, dimensional deviations will occur due to manufacturing, transportation, installation, and environmental temperature changes. These deviations can readily lead to excessive assembly stress or failure in bolt connection, thereby affecting structural safety and assembly efficiency. A dimensional chain tolerance control technique for components, installation units, and structural units is proposed. Through tolerance allocation and fit design, the dimensional deviations caused by manufacturing, transportation, installation, and environmental temperature changes are accommodated. This enables accurate, efficient, and stress-free structural assembly and ensures high assembly quality. This technique was successfully applied to a long-span H-shaped steel truss roof structure at an airport terminal, achieving high-precision tolerance control in fully bolted assembly.
The installation of long-span fully bolted steel structures is carried out using a multi-stage connection process. If components are manufactured solely based on nominal dimensions, dimensional deviations will occur due to manufacturing, transportation, installation, and environmental temperature changes. These deviations can readily lead to excessive assembly stress or failure in bolt connection, thereby affecting structural safety and assembly efficiency. A dimensional chain tolerance control technique for components, installation units, and structural units is proposed. Through tolerance allocation and fit design, the dimensional deviations caused by manufacturing, transportation, installation, and environmental temperature changes are accommodated. This enables accurate, efficient, and stress-free structural assembly and ensures high assembly quality. This technique was successfully applied to a long-span H-shaped steel truss roof structure at an airport terminal, achieving high-precision tolerance control in fully bolted assembly.
2025, 55(8): 84-89.
doi: 10.3724/j.gyjzG25061701
Abstract:
Whether the quality of high-efficiency standardized steel structure can meet the requirements needs to be judged by quality inspection, and sampling inspection is currently the most commonly used method. According to the mathematical basis of counting sampling inspection, the binomial distribution was used to analyze the sampling scheme of the current specification, and the application risks of the user and the producer were given when the AQL of the received quality limit is 5% and 10%, respectively, which is conducive to the establishment of a clear understanding of risk for the producer and the user of the steel structure. At the same time, for the two cases of the AQL of the received quality limit being 3% and 8%, the determination guidelines were formulated and the risks of the user and the producer were clarified, which It can be used for quality checking of projects with higher quality requirements. For the inspection process for isolated batches of structural steel: for the cases of priority protection of the user, the analysis should be carried out for different levels of inspection, for cases with limit quality LQ of 5%, 10%, 15%, and 20%, respectively; for the case of priority protection of the producer, the analysis should be carried out for different levels of inspection, with acceptance quality limit ALQ of 5% and 10%, respectively; thus, a sampling plan for each inspection level, can be provided with priority protection for the user or priority protection for the producer.
Whether the quality of high-efficiency standardized steel structure can meet the requirements needs to be judged by quality inspection, and sampling inspection is currently the most commonly used method. According to the mathematical basis of counting sampling inspection, the binomial distribution was used to analyze the sampling scheme of the current specification, and the application risks of the user and the producer were given when the AQL of the received quality limit is 5% and 10%, respectively, which is conducive to the establishment of a clear understanding of risk for the producer and the user of the steel structure. At the same time, for the two cases of the AQL of the received quality limit being 3% and 8%, the determination guidelines were formulated and the risks of the user and the producer were clarified, which It can be used for quality checking of projects with higher quality requirements. For the inspection process for isolated batches of structural steel: for the cases of priority protection of the user, the analysis should be carried out for different levels of inspection, for cases with limit quality LQ of 5%, 10%, 15%, and 20%, respectively; for the case of priority protection of the producer, the analysis should be carried out for different levels of inspection, with acceptance quality limit ALQ of 5% and 10%, respectively; thus, a sampling plan for each inspection level, can be provided with priority protection for the user or priority protection for the producer.
2025, 55(8): 90-95.
doi: 10.3724/j.gyjzG25060906
Abstract:
The significance of high-performance standardized steel structure quality certification lies in reshaping quality trust and meeting project requirements. The system comprises three parts: product certification for high-performance standardized steel structure sections, key components, and component installation services. The certification spection mainly focuses on technical aspects, including production equipment, processes, and the quality of raw materials. 11 difference indicators between high-performance standardized and traditional steel structures were detailed, offering technical criteria for certification and unifying the certification scale and basis. This paper briefly introduces foreign steel structure certification, draws useful lessons for China’s steel structure certification work, and proposes suggestions for promoting high-performance standardized steel structure quality certification in China.
The significance of high-performance standardized steel structure quality certification lies in reshaping quality trust and meeting project requirements. The system comprises three parts: product certification for high-performance standardized steel structure sections, key components, and component installation services. The certification spection mainly focuses on technical aspects, including production equipment, processes, and the quality of raw materials. 11 difference indicators between high-performance standardized and traditional steel structures were detailed, offering technical criteria for certification and unifying the certification scale and basis. This paper briefly introduces foreign steel structure certification, draws useful lessons for China’s steel structure certification work, and proposes suggestions for promoting high-performance standardized steel structure quality certification in China.
2025, 55(8): 96-105.
doi: 10.3724/j.gyjzG23062205
Abstract:
In the context of urban development shifting from incremental construction to stock renewal, the utilization of spaces under viaducts can not only revitalize inefficient urban spaces but also contribute to refined urban management, as well as high-quality and efficient construction. Taking the spaces under under viaducts in Chengdu as the research object, this paper explores the strategies for optimizing and regenerating urban viaduct spaces from the perspective of catalysts. The old and new elements reinforce and complement each other to improve the existing urban functions and fill structural gaps. Based on the characteristics and utilization of the spaces under viaducts in Chengdu, the tactile medium is shaped from four perspectives: spatial, functional, cultural, and landscape. Optimization strategies are proposed, including spatial form reconstruction, integration of various functions, expression of urban culture, and creation of distinctive places. Through diversified micro-interventions, this paper aims to transform these spaces into catalysts for urban development, thereby driving the growth of surrounding areas.
In the context of urban development shifting from incremental construction to stock renewal, the utilization of spaces under viaducts can not only revitalize inefficient urban spaces but also contribute to refined urban management, as well as high-quality and efficient construction. Taking the spaces under under viaducts in Chengdu as the research object, this paper explores the strategies for optimizing and regenerating urban viaduct spaces from the perspective of catalysts. The old and new elements reinforce and complement each other to improve the existing urban functions and fill structural gaps. Based on the characteristics and utilization of the spaces under viaducts in Chengdu, the tactile medium is shaped from four perspectives: spatial, functional, cultural, and landscape. Optimization strategies are proposed, including spatial form reconstruction, integration of various functions, expression of urban culture, and creation of distinctive places. Through diversified micro-interventions, this paper aims to transform these spaces into catalysts for urban development, thereby driving the growth of surrounding areas.
2025, 55(8): 106-113.
doi: 10.3724/j.gyjzG24040505
Abstract:
With the popularization of the concept of "green development" and the deepening of the construction of new rural areas, the construction industry is focusing on the prefabrication and greening of rural houses. However, some prefabricated rural houses (e. g., block rural houses) in cold regions will produce thermal bridges between the enclosure and structural parts during the heating process, resulting in a large amount of heat loss. In this paper, a typical prefabricated thermal insulation block-type residence in a rural area of China’s cold region was selected. The thermal bridge of its enclosure structure was analyzed through on-site measurement and simulation, and the comprehensive heat transfer coefficients of thermal bridges with different constructions were compared. It was found that the thermal bridges at block splices and structural joints had a significant influence on the thermal insulation performance of the house. Effective thermal bridge-breaking measures were proposed. The results showed that the optimized insulated block wall and main structure were easier to construct, and the integrated heat transfer coefficient of the wall was reduced by 54.82% compared with the original scheme, while the integrated heat transfer coefficient at beams and columns was reduced by 97%. This study provides suggestions for the design and construction of insulated block farmhouses and demonstrates the great potential of rural houses in energy conservation and emission reduction.
With the popularization of the concept of "green development" and the deepening of the construction of new rural areas, the construction industry is focusing on the prefabrication and greening of rural houses. However, some prefabricated rural houses (e. g., block rural houses) in cold regions will produce thermal bridges between the enclosure and structural parts during the heating process, resulting in a large amount of heat loss. In this paper, a typical prefabricated thermal insulation block-type residence in a rural area of China’s cold region was selected. The thermal bridge of its enclosure structure was analyzed through on-site measurement and simulation, and the comprehensive heat transfer coefficients of thermal bridges with different constructions were compared. It was found that the thermal bridges at block splices and structural joints had a significant influence on the thermal insulation performance of the house. Effective thermal bridge-breaking measures were proposed. The results showed that the optimized insulated block wall and main structure were easier to construct, and the integrated heat transfer coefficient of the wall was reduced by 54.82% compared with the original scheme, while the integrated heat transfer coefficient at beams and columns was reduced by 97%. This study provides suggestions for the design and construction of insulated block farmhouses and demonstrates the great potential of rural houses in energy conservation and emission reduction.
2025, 55(8): 114-121.
doi: 10.3724/j.gyjzG25010602
Abstract:
As existing industrial buildings in cities, these structures bear the imprints of the industrial era and preserve the memories of urban history. They represent an important resource for sustainable utilization in contemporary urban renewal. However, in the context of urban renewal, how to renovate old industrial buildings in city centers—redefining their design and functions—remains a key challenge. The goal is to ensure that these buildings not only align with the neighborhood’s functional positioning and integrate into the city’s overall planning and development but also revitalize the architectural space and produce expected benefits. This is a problem that needs to be faced urgently. The behavioral trajectory and preference of the crowd in the transformed space reflect the actual demands for the industry, which determines the vitality of the architectural space and its economic potential. Therefore, this study investigated functional layout strategies for old industrial buildings, using Luoyang Fengdong Tools Factory as an example. By analyzing the multi-dimensional influencing factors faced by the functional layout strategies for old industrial buildings, on the basis of preliminary design positioning and functional programming concepts, this study employd Pedsim for crowd dynamics simulations to fully explore the spatial value attributes of the factory’s different segments, and then optimize the layout of the functional business forms. Adjusting the layout of high-commercial-value businesses in crowded areas realizes efficient matching of space, crowds, and businesses, and finally proposes functional layout strategies for old industrial factory districts that align with current urban renewal development needs to promote efficient allocation and utilization of resources.
As existing industrial buildings in cities, these structures bear the imprints of the industrial era and preserve the memories of urban history. They represent an important resource for sustainable utilization in contemporary urban renewal. However, in the context of urban renewal, how to renovate old industrial buildings in city centers—redefining their design and functions—remains a key challenge. The goal is to ensure that these buildings not only align with the neighborhood’s functional positioning and integrate into the city’s overall planning and development but also revitalize the architectural space and produce expected benefits. This is a problem that needs to be faced urgently. The behavioral trajectory and preference of the crowd in the transformed space reflect the actual demands for the industry, which determines the vitality of the architectural space and its economic potential. Therefore, this study investigated functional layout strategies for old industrial buildings, using Luoyang Fengdong Tools Factory as an example. By analyzing the multi-dimensional influencing factors faced by the functional layout strategies for old industrial buildings, on the basis of preliminary design positioning and functional programming concepts, this study employd Pedsim for crowd dynamics simulations to fully explore the spatial value attributes of the factory’s different segments, and then optimize the layout of the functional business forms. Adjusting the layout of high-commercial-value businesses in crowded areas realizes efficient matching of space, crowds, and businesses, and finally proposes functional layout strategies for old industrial factory districts that align with current urban renewal development needs to promote efficient allocation and utilization of resources.
2025, 55(8): 122-130.
doi: 10.3724/j.gyjzG23102508
Abstract:
Taking the cultural heritage along the Grassland Silk Road in Inner Mongolia as the research object, this paper used ArcGIS tools to locate and quantitatively analyze the spatial distribution characteristics of cultural heritage, and used the minimum cumulative resistance MCR model to carry out the single factor overlay analytic hierarchy process, so as to carry out the multi-objective suitability analysis, provide optimization basis for the comprehensive evaluation of the spatial location, construction scope and pattern of the Grassland Silk Road heritage corridor in Inner Mongolia, and generate the heritage corridor construction model. According to the research findings: 1) the cultural heritage along the Grassland Silk Road is concentrated in Hohhot-Baotou-Erdos of midwest and Chifeng of east of Inner Mongolia, and the spatial distribution pattern and trend are distributed along the southwest to northeast axis; 2) central area is with the highest suitability in site selection of heritage corridors. The highly suitable areas showed a point-like distribution with heritage points as the core, the medium-high suitable areas showed a "linear group + multi-point" distribution pattern, and the suitable areas showed a "ribbon" distribution in the central Inner Mongolia, staggered distributed with the medium and high suitable area; 3) through optimizing and selecting, we formed: 1 level-1 corridor main line (Alxa Right Banner-Tongliao section), 2 level-2 heritage corridor branch lines (Bayan Nur-Tongliao section, Ejin Banner-Hohhot section), and 1 level-3 heritage corridor branch line. The compound cultural heritage development network is with the main line as the core and assisted by branch lines.
Taking the cultural heritage along the Grassland Silk Road in Inner Mongolia as the research object, this paper used ArcGIS tools to locate and quantitatively analyze the spatial distribution characteristics of cultural heritage, and used the minimum cumulative resistance MCR model to carry out the single factor overlay analytic hierarchy process, so as to carry out the multi-objective suitability analysis, provide optimization basis for the comprehensive evaluation of the spatial location, construction scope and pattern of the Grassland Silk Road heritage corridor in Inner Mongolia, and generate the heritage corridor construction model. According to the research findings: 1) the cultural heritage along the Grassland Silk Road is concentrated in Hohhot-Baotou-Erdos of midwest and Chifeng of east of Inner Mongolia, and the spatial distribution pattern and trend are distributed along the southwest to northeast axis; 2) central area is with the highest suitability in site selection of heritage corridors. The highly suitable areas showed a point-like distribution with heritage points as the core, the medium-high suitable areas showed a "linear group + multi-point" distribution pattern, and the suitable areas showed a "ribbon" distribution in the central Inner Mongolia, staggered distributed with the medium and high suitable area; 3) through optimizing and selecting, we formed: 1 level-1 corridor main line (Alxa Right Banner-Tongliao section), 2 level-2 heritage corridor branch lines (Bayan Nur-Tongliao section, Ejin Banner-Hohhot section), and 1 level-3 heritage corridor branch line. The compound cultural heritage development network is with the main line as the core and assisted by branch lines.
2025, 55(8): 131-140.
doi: 10.3724/j.gyjzG24092605
Abstract:
The construction of walking-friendly communities under the Transit-Oriented Development (TOD) model is of great significance to the realization of sustainable urban development. However, many cities focus on the high-intensity development of TOD, paying insufficient attention to pedestrians’ walking perception experience. In this paper, the Importance-Performance Analysis (IPA) method was used to construct a perception evaluation model of the walking environment in TOD communities, based on five dimensions: convenience, diversity, aesthetics, restorative quality, and safety. Six typical TOD communities in Chengdu were selected as samples to assess their walking experience from the perspective of residents’ perceptions. The results showed that 9 factors—including supporting service facilities, leisure activity space, pavement flatness, and pedestrian right-of-way—performed poorly in the walking environment of TOD communities in Chengdu. At the same time, based on the resource dominance of the study area, the TOD communities were divided into three categories: commercial agglomeration, park network, and educational agglomeration. Among these, residents of the educational agglomeration communities paid more attention to restoration and diversity but reported lower satisfaction. Residents of commercial agglomeration TOD communities were less satisfied with restoration and safety. Meanwhile, the walking environment convenience in park network TOD communities failed to meet expectations. Finally, for different types of TOD communities, targeted strategies and measures were proposed from the aspects of healing function, slow traffic system, and walking safety.
The construction of walking-friendly communities under the Transit-Oriented Development (TOD) model is of great significance to the realization of sustainable urban development. However, many cities focus on the high-intensity development of TOD, paying insufficient attention to pedestrians’ walking perception experience. In this paper, the Importance-Performance Analysis (IPA) method was used to construct a perception evaluation model of the walking environment in TOD communities, based on five dimensions: convenience, diversity, aesthetics, restorative quality, and safety. Six typical TOD communities in Chengdu were selected as samples to assess their walking experience from the perspective of residents’ perceptions. The results showed that 9 factors—including supporting service facilities, leisure activity space, pavement flatness, and pedestrian right-of-way—performed poorly in the walking environment of TOD communities in Chengdu. At the same time, based on the resource dominance of the study area, the TOD communities were divided into three categories: commercial agglomeration, park network, and educational agglomeration. Among these, residents of the educational agglomeration communities paid more attention to restoration and diversity but reported lower satisfaction. Residents of commercial agglomeration TOD communities were less satisfied with restoration and safety. Meanwhile, the walking environment convenience in park network TOD communities failed to meet expectations. Finally, for different types of TOD communities, targeted strategies and measures were proposed from the aspects of healing function, slow traffic system, and walking safety.
2025, 55(8): 141-146.
doi: 10.3724/j.gyjzG24110102
Abstract:
Given the critical requirements for both safety and comfort in kindergarten buildings, the seismic performance has been enhanced to ensure the structure remains undamaged under a moderate earthquake, while also incorporating design features for easier repair following a major seismic event. Based on a steel-structural ultra-low energy consumption kindergarten project in Beijing, a high-performance concrete steel bar truss floor system was adopted to enhance structural strength, thermal insulation, waterproofing, and durability. For seismic design, viscous dampers were incorporated. Through optimized layout of energy dissipation components, the stiffness and additional damping ratios were similar in both principal directions. The main structure achieved the performance objective of remaining undamaged under moderate earthquakes and being repairable following major earthquakes. As an ultra-low energy consumption building, the project required that the design method for its conventional envelope system be compatible with the required deformation capacity. To address this, basalt composite fiberintegrated exterior wall panels were employed. They offered a mere 30% of the weight of conventional systems with a compressive strength ranging from 200 to 400 MPa. They accommodated an inter-story drift ratio of 1/100, matching the seismic performance requirements of the building. Their thermal insulation performance also met the requirements of ultra-low energy consumption buildings, enabling the structure to remain functional and undamaged under moderate earthquakes. This paper investigates a dual-objective integrated design approach where the enhancement of seismic performance serves as the primary driver, aligned with the improvement of comfort performance.
Given the critical requirements for both safety and comfort in kindergarten buildings, the seismic performance has been enhanced to ensure the structure remains undamaged under a moderate earthquake, while also incorporating design features for easier repair following a major seismic event. Based on a steel-structural ultra-low energy consumption kindergarten project in Beijing, a high-performance concrete steel bar truss floor system was adopted to enhance structural strength, thermal insulation, waterproofing, and durability. For seismic design, viscous dampers were incorporated. Through optimized layout of energy dissipation components, the stiffness and additional damping ratios were similar in both principal directions. The main structure achieved the performance objective of remaining undamaged under moderate earthquakes and being repairable following major earthquakes. As an ultra-low energy consumption building, the project required that the design method for its conventional envelope system be compatible with the required deformation capacity. To address this, basalt composite fiberintegrated exterior wall panels were employed. They offered a mere 30% of the weight of conventional systems with a compressive strength ranging from 200 to 400 MPa. They accommodated an inter-story drift ratio of 1/100, matching the seismic performance requirements of the building. Their thermal insulation performance also met the requirements of ultra-low energy consumption buildings, enabling the structure to remain functional and undamaged under moderate earthquakes. This paper investigates a dual-objective integrated design approach where the enhancement of seismic performance serves as the primary driver, aligned with the improvement of comfort performance.
2025, 55(8): 147-156.
doi: 10.3724/j.gyjzG22062210
Abstract:
In order to explore the influence of self-drilling self-tapping screws (parameters such as head type, material, diameter, threads per inch, washers, etc.) and connected materials (edge distance) on the failure modes and shear bearing capacity of the connections in enclosure systems, an experimental study of mechanical properties was conducted on 93 groups of specimens of two types of joints connected by carbon steel and stainless steel composite screws fastened to 445J2 stainless steel plates based on steel substrates. The failure modes of these two types of joints were analyzed, and the parameters influencing the shear bearing capacity of the joints were revealed. The results showed that both types of joints exhibited a failure mode where the self-drilling self-tapping screws, 445J2 stainless steel plates, and steel substrates jointly bear the external load. This was followed by progressive damage and deformation at the engagement between the screws and the 445J2 stainless steel plates, ultimately leading to shear failure of the stainless steel plates. The screw holes showed an enlarged failure mode along the loading direction. The parameters of self-drilling self-tapping screws had a significant impact on the shear bearing capacity of the joints. The peak shear bearing capacity achieved the maximum improvement of 48.4% when different types of screw heads were adopted. In contrast, the edge distance (margin) showed no clear trend in its effect on the shear bearing capacity of the connection nodes, with the peak shear capacity varying only by 9.5% at the highest.
In order to explore the influence of self-drilling self-tapping screws (parameters such as head type, material, diameter, threads per inch, washers, etc.) and connected materials (edge distance) on the failure modes and shear bearing capacity of the connections in enclosure systems, an experimental study of mechanical properties was conducted on 93 groups of specimens of two types of joints connected by carbon steel and stainless steel composite screws fastened to 445J2 stainless steel plates based on steel substrates. The failure modes of these two types of joints were analyzed, and the parameters influencing the shear bearing capacity of the joints were revealed. The results showed that both types of joints exhibited a failure mode where the self-drilling self-tapping screws, 445J2 stainless steel plates, and steel substrates jointly bear the external load. This was followed by progressive damage and deformation at the engagement between the screws and the 445J2 stainless steel plates, ultimately leading to shear failure of the stainless steel plates. The screw holes showed an enlarged failure mode along the loading direction. The parameters of self-drilling self-tapping screws had a significant impact on the shear bearing capacity of the joints. The peak shear bearing capacity achieved the maximum improvement of 48.4% when different types of screw heads were adopted. In contrast, the edge distance (margin) showed no clear trend in its effect on the shear bearing capacity of the connection nodes, with the peak shear capacity varying only by 9.5% at the highest.
2025, 55(8): 157-167.
doi: 10.3724/j.gyjzG24071104
Abstract:
Reinforced hollow high-strength/ultra-high strength concrete-filled square steel tubular (RHHS-CFST) columns are a kind of prefabricated members with advantages such as mature production techniques, low cos, light weight, and high bearing capacity. As prefabricated components, they hold broad application potential in engineering structures, particularly for long-span foundation excavation support systems and multi-level parking facilities. However, there is no design method capable of accurately predicting the axial compressive bearing capacity of this member. The available design methods cannot account for the influence of high concrete strength (exceeding C80 grade) or the early buckling of the steel tube caused by the high hollow ratio and insufficient wall thickness. To address this issue, this paper conducted a systematic parametric investigation with a reliable finite element modeling method (FEM). Subsequently, a new expression was proposed to predict the axial compressive bearing capacity based on available test data and finite element analytical results. The results showed that the hollow ratio and width-to-thickness ratio of the steel tube significantly affected the axial compressive bearing capacity. For the members with a hollow ratio greater than 0.25 and a width-to-thickness ratio unsatisfying the requirements of current design codes for concrete-filled steel tubes, local buckling of the steel tube might occur before reaching the peak load, leading to a reduction in strength. The predicted results from the proposed expression matched well with the FEM results and test data. The average ratio of predicted to measured/FEM results was 0.935, with a coefficient of variation of 0.108. This indicates that the proposed design method can safely predict the axial compressive bearing capacity of RHHS-CFST members. The highest overestimation by the proposed design method was only 8.6%.
Reinforced hollow high-strength/ultra-high strength concrete-filled square steel tubular (RHHS-CFST) columns are a kind of prefabricated members with advantages such as mature production techniques, low cos, light weight, and high bearing capacity. As prefabricated components, they hold broad application potential in engineering structures, particularly for long-span foundation excavation support systems and multi-level parking facilities. However, there is no design method capable of accurately predicting the axial compressive bearing capacity of this member. The available design methods cannot account for the influence of high concrete strength (exceeding C80 grade) or the early buckling of the steel tube caused by the high hollow ratio and insufficient wall thickness. To address this issue, this paper conducted a systematic parametric investigation with a reliable finite element modeling method (FEM). Subsequently, a new expression was proposed to predict the axial compressive bearing capacity based on available test data and finite element analytical results. The results showed that the hollow ratio and width-to-thickness ratio of the steel tube significantly affected the axial compressive bearing capacity. For the members with a hollow ratio greater than 0.25 and a width-to-thickness ratio unsatisfying the requirements of current design codes for concrete-filled steel tubes, local buckling of the steel tube might occur before reaching the peak load, leading to a reduction in strength. The predicted results from the proposed expression matched well with the FEM results and test data. The average ratio of predicted to measured/FEM results was 0.935, with a coefficient of variation of 0.108. This indicates that the proposed design method can safely predict the axial compressive bearing capacity of RHHS-CFST members. The highest overestimation by the proposed design method was only 8.6%.
2025, 55(8): 168-175.
doi: 10.3724/j.gyjzG24062605
Abstract:
Based on the Unified Standard for Reliability Design of Building Structures (GB 50068—2018), the reliability of shear bearing capacity design formulas in the Technical Standard For Steel Reinforced Concrete Structures With Specially-Shaped Columns (T/CSCS 014—2021) was examined by taking the reliability of shear bearing capacity of solid-web steel-reinforced concrete special-shaped columns as the research object. Relying on the MATLAB calculation platform, calculation programs for the JC method and Monte Carlo simulation method were prepared respectively. On this basis, the effects of random variables—such as shear-span-ratio, concrete strength grade, hoop strength, section steel strength, axial compression ratio, load effect ratio, and live load type—on the reliability index of shear bearing capacity of solid-web steel-reinforced concrete special-shaped columns were analyzed. The performance of the target calculation formula was also evaluated. The results showed that under most working conditions, the reliability index of shear bearing capacity of solid-web steel-reinforced concrete special-shaped columns—calculated based on the load partial factors specified in GB 50068—2018—met the requirements but was conservative. It is suggested that the partial factor for constant loads should be adjusted to 1.2 to balance both reliability and economic benefits.
Based on the Unified Standard for Reliability Design of Building Structures (GB 50068—2018), the reliability of shear bearing capacity design formulas in the Technical Standard For Steel Reinforced Concrete Structures With Specially-Shaped Columns (T/CSCS 014—2021) was examined by taking the reliability of shear bearing capacity of solid-web steel-reinforced concrete special-shaped columns as the research object. Relying on the MATLAB calculation platform, calculation programs for the JC method and Monte Carlo simulation method were prepared respectively. On this basis, the effects of random variables—such as shear-span-ratio, concrete strength grade, hoop strength, section steel strength, axial compression ratio, load effect ratio, and live load type—on the reliability index of shear bearing capacity of solid-web steel-reinforced concrete special-shaped columns were analyzed. The performance of the target calculation formula was also evaluated. The results showed that under most working conditions, the reliability index of shear bearing capacity of solid-web steel-reinforced concrete special-shaped columns—calculated based on the load partial factors specified in GB 50068—2018—met the requirements but was conservative. It is suggested that the partial factor for constant loads should be adjusted to 1.2 to balance both reliability and economic benefits.
2025, 55(8): 176-184.
doi: 10.3724/j.gyjzG25060405
Abstract:
Pretensioned T-beams with folded lines exhibit high bearing capacity and long span, demonstrating broad application prospects in bridge engineering. For prestressed beams, the presence or absence of cracking is a key indicator to determine whether they remain in a normal working state. As the prestress is mainly transferred through the bonding force between steel strands and concrete, cracking can lead to direct exposure of the internal prestressed reinforcement to corrosive medium. This weakens the bonding performance and significantly compromises the structure’s durability and safety. Based on practical engineering, this study presents the design of a novel 30 m pretensioned polygonal prestressed T-beam. Through full-scale experiments and finite element model numerical analysis, the crack resistance of the inclined section at the beam end under a shear span ratio of λ = 2.5 was studied. The experiment adopted a graded loading method. Test results indicated that cracks initially appeared at the bottom of the upper flange and the lower flange edge near the loading section, then developed diagonally in the tension zone adjacent to the loading section and the upper part of the web plate of the beam end. These cracks were mainly concentrated along both sides of the line connecting the loading point and the fulcrum. The measured shear force for cracking of the test beam segment was 1766 kN, while the design shear force was 962.6 kN. The ratio of the measured to the design value was 1.835, indicating that the novel T-beam exhibits excellent crack resistance. Furthermore, a finite element numerical model of the beam was developed. The results showed that the predicted strain distribution in the web plate under the cracking load agreed well with the measured results, providing a reference for the crack resistance assessment of the diagonal section of novel prestressed T-beams.
Pretensioned T-beams with folded lines exhibit high bearing capacity and long span, demonstrating broad application prospects in bridge engineering. For prestressed beams, the presence or absence of cracking is a key indicator to determine whether they remain in a normal working state. As the prestress is mainly transferred through the bonding force between steel strands and concrete, cracking can lead to direct exposure of the internal prestressed reinforcement to corrosive medium. This weakens the bonding performance and significantly compromises the structure’s durability and safety. Based on practical engineering, this study presents the design of a novel 30 m pretensioned polygonal prestressed T-beam. Through full-scale experiments and finite element model numerical analysis, the crack resistance of the inclined section at the beam end under a shear span ratio of λ = 2.5 was studied. The experiment adopted a graded loading method. Test results indicated that cracks initially appeared at the bottom of the upper flange and the lower flange edge near the loading section, then developed diagonally in the tension zone adjacent to the loading section and the upper part of the web plate of the beam end. These cracks were mainly concentrated along both sides of the line connecting the loading point and the fulcrum. The measured shear force for cracking of the test beam segment was 1766 kN, while the design shear force was 962.6 kN. The ratio of the measured to the design value was 1.835, indicating that the novel T-beam exhibits excellent crack resistance. Furthermore, a finite element numerical model of the beam was developed. The results showed that the predicted strain distribution in the web plate under the cracking load agreed well with the measured results, providing a reference for the crack resistance assessment of the diagonal section of novel prestressed T-beams.
2025, 55(8): 185-192.
doi: 10.3724/j.gyjzG23041014
Abstract:
In order to analyze the applicability and reasonable construction details of PBL shear connectors in curved steel box girder steel-concrete composite bridge decks, a local finite element model of the segment considering the influence of global effects was established based on ABAQUS software. The reliability of the finite element model was verified through a comparison with actual bridge loading tests. A comparative analysis was conducted between the new steel-concrete composite bridge deck and the original design. Central Composite Design (CCD) experimental design method was used to conduct finite element analysis at 25 test points. Design Expert software was used to establish an optimized response surface model for the composite bridge deck structure. Three sets of optimized design schemes were obtained through multi-objective optimization. After a comprehensive analysis, the final optimized design results were obtained: the thickness of the steel box girder top plate was set at 18 mm, the thickness of the perforated steel plate for the shear connectors was set at 12 mm, the transverse spacing of the shear connectors was set at 250 mm, and the concrete thickness was set at 120 mm. This resulted in a 23.12% reduction in steel usage and a 17.50% reduction in the number of welds. The cost of the composite bridge deck increased by 10.41% compared to the initial design parameters, yet remained lower than that of the original structure. The mechanical indicators of the bridge deck showed significant improvement, with a particularly notable reduction in the maximum tensile stress of the concrete. These results demonstrated the effectiveness of the optimization.
In order to analyze the applicability and reasonable construction details of PBL shear connectors in curved steel box girder steel-concrete composite bridge decks, a local finite element model of the segment considering the influence of global effects was established based on ABAQUS software. The reliability of the finite element model was verified through a comparison with actual bridge loading tests. A comparative analysis was conducted between the new steel-concrete composite bridge deck and the original design. Central Composite Design (CCD) experimental design method was used to conduct finite element analysis at 25 test points. Design Expert software was used to establish an optimized response surface model for the composite bridge deck structure. Three sets of optimized design schemes were obtained through multi-objective optimization. After a comprehensive analysis, the final optimized design results were obtained: the thickness of the steel box girder top plate was set at 18 mm, the thickness of the perforated steel plate for the shear connectors was set at 12 mm, the transverse spacing of the shear connectors was set at 250 mm, and the concrete thickness was set at 120 mm. This resulted in a 23.12% reduction in steel usage and a 17.50% reduction in the number of welds. The cost of the composite bridge deck increased by 10.41% compared to the initial design parameters, yet remained lower than that of the original structure. The mechanical indicators of the bridge deck showed significant improvement, with a particularly notable reduction in the maximum tensile stress of the concrete. These results demonstrated the effectiveness of the optimization.
2025, 55(8): 193-199.
doi: 10.3724/j.gyjzG24062106
Abstract:
The integrity test of the containment is one of the most crucial tests during the operation of nuclear power plants. To optimize and improve the pressurization rate for this test, the heat transfer mechanism of gas movement inside the containment during the experimental process was analyzed, and reasonable thermal boundary conditions for the gas were proposed. The computational fluid dynamics (CFD) method adopted used to establish a refined simulation analysis model for the fluid domain inside the containment. Historical data from the integrity test of the containment were employed to verify the reliability of the model. Based on the validated model, an analysis was conducted on the gas movement inside the containment after increasing the pressurization rate to 60 kPa/h. The results showed that the gas inside the containment flowed slowly, with a maximum average velocity of 0.165 m/s. The gas temperature exhibited a nonlinear change, rising by an average of 5.75℃. During pressurization, the gas pressure was uniformly distributed, and except for a range of 2 meters near the pressurization port, the pressure gradient in all other areas did not exceed 5 Pa. In summary, increasing the pressurization rate to 60 kPa/h caused only minor changes to the gas state inside the vessel.
The integrity test of the containment is one of the most crucial tests during the operation of nuclear power plants. To optimize and improve the pressurization rate for this test, the heat transfer mechanism of gas movement inside the containment during the experimental process was analyzed, and reasonable thermal boundary conditions for the gas were proposed. The computational fluid dynamics (CFD) method adopted used to establish a refined simulation analysis model for the fluid domain inside the containment. Historical data from the integrity test of the containment were employed to verify the reliability of the model. Based on the validated model, an analysis was conducted on the gas movement inside the containment after increasing the pressurization rate to 60 kPa/h. The results showed that the gas inside the containment flowed slowly, with a maximum average velocity of 0.165 m/s. The gas temperature exhibited a nonlinear change, rising by an average of 5.75℃. During pressurization, the gas pressure was uniformly distributed, and except for a range of 2 meters near the pressurization port, the pressure gradient in all other areas did not exceed 5 Pa. In summary, increasing the pressurization rate to 60 kPa/h caused only minor changes to the gas state inside the vessel.
2025, 55(8): 200-209.
doi: 10.3724/j.gyjzG22061805
Abstract:
In recent years, steel-structure cooling towers have been widely used in thermal power generation systems due to their lightweight yet high-strength, excellent seismic performance, and short construction period. According to their structural characteristics, there are currently two main types of cooling towers: the hyperbolic tower and the cylinder-frustum tower. Different from the hyperbolic tower type, which features a continuous surface with negative Gaussian curvature, the cylinder-frustum tower type consists of surfaces with zero Gaussian curvature at both ends. Additionally, the tower body exhibits distinct geometric abruptions. The differences in force characteristics and static behavior caused by different tower types are not yet clear. Therefore, using the numerical simulation method, a static behavior analysis was conducted on cylinder-frustum and hyperbolic steel cooling towers with different heights and structural systems. The differences in the static behavior of the two tower types were compared in terms of force transmission characteristics, structural deformation, and bearing capacity.
In recent years, steel-structure cooling towers have been widely used in thermal power generation systems due to their lightweight yet high-strength, excellent seismic performance, and short construction period. According to their structural characteristics, there are currently two main types of cooling towers: the hyperbolic tower and the cylinder-frustum tower. Different from the hyperbolic tower type, which features a continuous surface with negative Gaussian curvature, the cylinder-frustum tower type consists of surfaces with zero Gaussian curvature at both ends. Additionally, the tower body exhibits distinct geometric abruptions. The differences in force characteristics and static behavior caused by different tower types are not yet clear. Therefore, using the numerical simulation method, a static behavior analysis was conducted on cylinder-frustum and hyperbolic steel cooling towers with different heights and structural systems. The differences in the static behavior of the two tower types were compared in terms of force transmission characteristics, structural deformation, and bearing capacity.
2025, 55(8): 210-216.
doi: 10.3724/j.gyjzG23012603
Abstract:
A finite element model of the insulator-string-conductor system was established to investigate the influence of uneven ice-coating on the dynamic responses of iced transmission lines subjected to ice-shedding. Three parameters of ice section location, ice section length, and basic ice thickness were defined to characterize the non-uniform ice-coating conditions. The ice-shedding dynamic responses of non-uniformly iced conductors under different icing characteristics and line parameters were analyzed. Furthermore, the influence law of each parameter on the maximum ice-jump amplitude and the maximum unbalanced tension was studied. The numerical results showed that for the same total ice load on the ice-shedding span, non-uniformly iced conductors generated more severe ice-shedding responses compared to uniformly iced conductors; the most unfavorable position of the non-uniformly iced segment was related to the span length. When the ice-shedding span was 700 m or less, the closer the position of the non-uniformly iced segment was to the mid-span, the greater the conductor’s jump height and unbalanced tension became. When the length of ice-shedding span exceeded 700 m, the condition became more unfavorable if the ratio of the horizontal distance (between the midpoint of the iced segment and the left suspension point) to the span length was 0.3.
A finite element model of the insulator-string-conductor system was established to investigate the influence of uneven ice-coating on the dynamic responses of iced transmission lines subjected to ice-shedding. Three parameters of ice section location, ice section length, and basic ice thickness were defined to characterize the non-uniform ice-coating conditions. The ice-shedding dynamic responses of non-uniformly iced conductors under different icing characteristics and line parameters were analyzed. Furthermore, the influence law of each parameter on the maximum ice-jump amplitude and the maximum unbalanced tension was studied. The numerical results showed that for the same total ice load on the ice-shedding span, non-uniformly iced conductors generated more severe ice-shedding responses compared to uniformly iced conductors; the most unfavorable position of the non-uniformly iced segment was related to the span length. When the ice-shedding span was 700 m or less, the closer the position of the non-uniformly iced segment was to the mid-span, the greater the conductor’s jump height and unbalanced tension became. When the length of ice-shedding span exceeded 700 m, the condition became more unfavorable if the ratio of the horizontal distance (between the midpoint of the iced segment and the left suspension point) to the span length was 0.3.
2025, 55(8): 217-225.
doi: 10.3724/j.gyjzG23091910
Abstract:
In order to calibrate the micromechanism-based fracture model parameters for five austenitic stainless steel S30408 materials—base metal, longitudinal welds, transverse welds, longitudinal heataffected zone (HAZ), and transverse HAZ—standard smooth round bar tensile tests and notched round bar tensile tests were conducted, along with scanning electron microscopy (SEM) examination of the fracture surfaces. These tests provided the constitutive parameters and characteristic lengths for each material. The entire loading process of the notched round bar specimen was simulated using the finite element method (FEM), and the micromechanical fracture toughness parameters for each material were calibrated based on the Void Growth Model (VGM) and the Stress-Modified Critical Strain (SMCS) model. The results showed that the values of the toughness parameters α and η for S30408 welds were smaller than those of the base metal and the HAZ material, indicating that the weld material was more prone to cracking. The calibrated fracture toughness parameters all exhibited coefficients of variation less than 12%, which validated the effectiveness of the micromechanism-based fracture model in predicting ductile fracture of austenitic stainless steel S30408 base metal, welds, and HAZ materials. Compared to conventional carbon steel, the base metal of austenitic stainless steel S30408 exhibited significantly superior fracture toughness, while its welds demonstrated the poorest performance.
In order to calibrate the micromechanism-based fracture model parameters for five austenitic stainless steel S30408 materials—base metal, longitudinal welds, transverse welds, longitudinal heataffected zone (HAZ), and transverse HAZ—standard smooth round bar tensile tests and notched round bar tensile tests were conducted, along with scanning electron microscopy (SEM) examination of the fracture surfaces. These tests provided the constitutive parameters and characteristic lengths for each material. The entire loading process of the notched round bar specimen was simulated using the finite element method (FEM), and the micromechanical fracture toughness parameters for each material were calibrated based on the Void Growth Model (VGM) and the Stress-Modified Critical Strain (SMCS) model. The results showed that the values of the toughness parameters α and η for S30408 welds were smaller than those of the base metal and the HAZ material, indicating that the weld material was more prone to cracking. The calibrated fracture toughness parameters all exhibited coefficients of variation less than 12%, which validated the effectiveness of the micromechanism-based fracture model in predicting ductile fracture of austenitic stainless steel S30408 base metal, welds, and HAZ materials. Compared to conventional carbon steel, the base metal of austenitic stainless steel S30408 exhibited significantly superior fracture toughness, while its welds demonstrated the poorest performance.
2025, 55(8): 226-235.
doi: 10.3724/j.gyjzG25051101
Abstract:
In order to realize the multi-objective optimal design of the mix proportion for fiber-reinforced concrete, this paper adopted the response surface method to investigate the effects of the contents of polypropylene fiber, silica fume, and microbeads, as well as their interactions, on the workability and mechanical properties of fiber-reinforced concrete. Furthermore, it carried out multi-objective optimization analysis to determine the optimal mix proportion. The results showed that the regression model established in this paper exhibited remarkable fitting accuracy and credibility. Among the interactions of various factors, the most significant effects on slump flow, 28-day compressive strength, and flexural strength of fiber-reinforced concrete were attributed to the interactions between silica fume and microbeads, polypropylene fiber and silica fume, and polypropylene fiber and microbeads, respectively. The multi-objective optimization analysis revealed that the optimal mix proportion parameters for fiber-reinforced concrete were as follows: polypropylene fiber content of 1.62%, silica fume content of 8.56%, and microbead content of 10%. Under these conditions, the slump flow, 28-day compressive strength, and flexural strength reached 655 mm, 64.1 MPa, and 13.4 MPa, respectively, meeting the target response requirements. This study verifies the feasibility of using the response surface methodology for multi-objective optimization of mining concrete materials.
In order to realize the multi-objective optimal design of the mix proportion for fiber-reinforced concrete, this paper adopted the response surface method to investigate the effects of the contents of polypropylene fiber, silica fume, and microbeads, as well as their interactions, on the workability and mechanical properties of fiber-reinforced concrete. Furthermore, it carried out multi-objective optimization analysis to determine the optimal mix proportion. The results showed that the regression model established in this paper exhibited remarkable fitting accuracy and credibility. Among the interactions of various factors, the most significant effects on slump flow, 28-day compressive strength, and flexural strength of fiber-reinforced concrete were attributed to the interactions between silica fume and microbeads, polypropylene fiber and silica fume, and polypropylene fiber and microbeads, respectively. The multi-objective optimization analysis revealed that the optimal mix proportion parameters for fiber-reinforced concrete were as follows: polypropylene fiber content of 1.62%, silica fume content of 8.56%, and microbead content of 10%. Under these conditions, the slump flow, 28-day compressive strength, and flexural strength reached 655 mm, 64.1 MPa, and 13.4 MPa, respectively, meeting the target response requirements. This study verifies the feasibility of using the response surface methodology for multi-objective optimization of mining concrete materials.
2025, 55(8): 236-241.
doi: 10.3724/j.gyjzG23071403
Abstract:
Based on static load tests and rock foundation load tests conducted on four large-diameter rock-socketed piles in a Chongqing project, the influence of construction quality on the vertical compressive bearing capacity of rock-socketed piles in soft rock was discussed. The results indicated that the vertical compressive bearing capacity of rock-socketed piles was greatly affected by both the construction quality of pile foundation and the sediment thickness at the pile base. Based on design standards, if the vertical compressive bearing capacity of the embedded rock section of rock-socketed piles in soft rock needs to be significantly increased through experimental verification, the construction quality and acceptance criteria for the pile foundation must be clearly specified.
Based on static load tests and rock foundation load tests conducted on four large-diameter rock-socketed piles in a Chongqing project, the influence of construction quality on the vertical compressive bearing capacity of rock-socketed piles in soft rock was discussed. The results indicated that the vertical compressive bearing capacity of rock-socketed piles was greatly affected by both the construction quality of pile foundation and the sediment thickness at the pile base. Based on design standards, if the vertical compressive bearing capacity of the embedded rock section of rock-socketed piles in soft rock needs to be significantly increased through experimental verification, the construction quality and acceptance criteria for the pile foundation must be clearly specified.
2025, 55(8): 242-249.
doi: 10.3724/j.gyjzG23061210
Abstract:
The vacuum preloading method, used by the Zhejiang Engineering Research Center for Disaster Prevention and Reduction of Coastal Soft Soil Foundation, faces issues such as a slow drainage consolidation rate and poor post-treatment effect when treating engineering waste mud. The vacuum preloading combined with heating method is an innovative improvement on the conventional vacuum preloading method, explored by domestic and international researchers in recent years, but related research remains at the exploratory stage. A self-made temperature-controlled model test device was used to design and conduct comparative experiments on the vacuum preloading combined with heating method under different prefabricated vertical drain (PVD) arrangements. The development trends of parameters such as temperature, drainage volume, soil surface settlement, and pore pressure in engineering waste mud under different PVD arrangements were analyzed in detail. The results showed that, compared with the hexagonal layout, the equilateral triangle layout improved the consolidation effect of soil, achieving consolidation degrees 5.5% and 8% higher than those of the square and hexagonal layouts, respectively; compared with the regular hexagonal layout, its cumulative soil displacement and pore pressure dissipation increased 15% and 22.04%, respectively. The findings of this experiment provide an important reference for applying the vacuum preloading combined with heating method in treating engineering waste mud, offering significant practical value for engineering applications.
The vacuum preloading method, used by the Zhejiang Engineering Research Center for Disaster Prevention and Reduction of Coastal Soft Soil Foundation, faces issues such as a slow drainage consolidation rate and poor post-treatment effect when treating engineering waste mud. The vacuum preloading combined with heating method is an innovative improvement on the conventional vacuum preloading method, explored by domestic and international researchers in recent years, but related research remains at the exploratory stage. A self-made temperature-controlled model test device was used to design and conduct comparative experiments on the vacuum preloading combined with heating method under different prefabricated vertical drain (PVD) arrangements. The development trends of parameters such as temperature, drainage volume, soil surface settlement, and pore pressure in engineering waste mud under different PVD arrangements were analyzed in detail. The results showed that, compared with the hexagonal layout, the equilateral triangle layout improved the consolidation effect of soil, achieving consolidation degrees 5.5% and 8% higher than those of the square and hexagonal layouts, respectively; compared with the regular hexagonal layout, its cumulative soil displacement and pore pressure dissipation increased 15% and 22.04%, respectively. The findings of this experiment provide an important reference for applying the vacuum preloading combined with heating method in treating engineering waste mud, offering significant practical value for engineering applications.
2025, 55(8): 250-257.
doi: 10.3724/j.gyjzG23091213
Abstract:
The vigorous promotion of construction waste resource utilization and disposal is a key requirement and trend under the sustainable development strategy. Recycled concrete aggregate, which is produced from crushed construction waste, has broad potential applications. This study investigated the shear characteristics of the interface between recycled concrete aggregate and typical red sandstone soil from the Gannan region under reinforced conditions through large-scale indoor direct shear tests. The results showed that as the aperture ratio decreased, both the peak shear stress and residual shear stresse increased, while the time lag to reach peak shear stress also increased gradually. Additionally, with decreasing aperture ratio, the apparent cohesion and internal friction angle increased gradually. For samples of red sandstone soil with a moisture content not exceeding 12.7% (the optimum moisture content), both the peak shear stress and residual shear stress gradually decreased as the moisture content increased. Similarly, the apparent cohesion and internal friction angle also decreased gradually with the increase of moisture content. Under different aperture ratios and moisture contents of red sandstone soil, both the peak shear stress and residual shear stress increased with higher vertical stress. The shear stiffness expression was derived through linear fitting and power function fitting, incorporating the Kalhaway constitutive equation.
The vigorous promotion of construction waste resource utilization and disposal is a key requirement and trend under the sustainable development strategy. Recycled concrete aggregate, which is produced from crushed construction waste, has broad potential applications. This study investigated the shear characteristics of the interface between recycled concrete aggregate and typical red sandstone soil from the Gannan region under reinforced conditions through large-scale indoor direct shear tests. The results showed that as the aperture ratio decreased, both the peak shear stress and residual shear stresse increased, while the time lag to reach peak shear stress also increased gradually. Additionally, with decreasing aperture ratio, the apparent cohesion and internal friction angle increased gradually. For samples of red sandstone soil with a moisture content not exceeding 12.7% (the optimum moisture content), both the peak shear stress and residual shear stress gradually decreased as the moisture content increased. Similarly, the apparent cohesion and internal friction angle also decreased gradually with the increase of moisture content. Under different aperture ratios and moisture contents of red sandstone soil, both the peak shear stress and residual shear stress increased with higher vertical stress. The shear stiffness expression was derived through linear fitting and power function fitting, incorporating the Kalhaway constitutive equation.
2025, 55(8): 258-267.
doi: 10.3724/j.gyjzG23103017
Abstract:
With the rapid development of urban rail transit, a large number of small-clearance tunnel shield projects have emerged, among which the theory of small-clearance tunnel construction design for three-lane tunnels has not yet been well established. Based on an actual project, this paper conducted an optimization analysis of the construction sequence, designed four excavation conditions, and examined the influence of the longitudinal spacing between tunnel excavation surfaces on surface settlement, segment displacement, and surrounding rock pressure. The results showed that: the sinkholes under the four conditions were all V-shaped, with a width of approximately 55 m (9D); the peak settlement in Case 4, where the middle tunnel was excavated first, was 10.16 mm, smaller than that in Case 2, where the tunnels on both sides were excavated first (11.10 mm); the range of ground surface settlement extended from 2.5D behind the excavation face to 1.5D ahead of the excavation face in the case of singlelane construction; when adjacent lines were constructed simultaneously and the axis spacing was less than 20 m, the working faces of the two tunnels maintained at least 16 m (2.5D) longitudinal spacing. When existing tunnels were present on the other side of the first tunnel, the longitudinal spacing of the excavation faces was kept at least 12 m (2D) to minimize the impact on ground surface settlement, segment displacement, and surrounding rock pressure.
With the rapid development of urban rail transit, a large number of small-clearance tunnel shield projects have emerged, among which the theory of small-clearance tunnel construction design for three-lane tunnels has not yet been well established. Based on an actual project, this paper conducted an optimization analysis of the construction sequence, designed four excavation conditions, and examined the influence of the longitudinal spacing between tunnel excavation surfaces on surface settlement, segment displacement, and surrounding rock pressure. The results showed that: the sinkholes under the four conditions were all V-shaped, with a width of approximately 55 m (9D); the peak settlement in Case 4, where the middle tunnel was excavated first, was 10.16 mm, smaller than that in Case 2, where the tunnels on both sides were excavated first (11.10 mm); the range of ground surface settlement extended from 2.5D behind the excavation face to 1.5D ahead of the excavation face in the case of singlelane construction; when adjacent lines were constructed simultaneously and the axis spacing was less than 20 m, the working faces of the two tunnels maintained at least 16 m (2.5D) longitudinal spacing. When existing tunnels were present on the other side of the first tunnel, the longitudinal spacing of the excavation faces was kept at least 12 m (2D) to minimize the impact on ground surface settlement, segment displacement, and surrounding rock pressure.
2025, 55(8): 268-276.
doi: 10.3724/j.gyjzG23112217
Abstract:
For small and medium-sized steel structure sports venues, a prestressed construction technology is proposed to reduce the impact of the construction process on the structural state and to fully utilize the characteristics of the steel structure itself, which has a certain elastic deformation range. The main feature of the process is to first construct the main truss, followed by the roof grid. After the main truss is completed, it is pulled down to a specific position (within its elastic range) using a pull-down cable, and the roof grid is connected to it. After all connections are completed, the tension in the pull-down cable is gradually released in stages. After the pull-down cable tension is released, the main truss experiences a certain degree of rebound. During this process, the roof grid forms a prestressed structure, and a stable whole is formed between the main truss and the roof. A numerical simulation was performed to analyze the construction process and determine the optimal prestressed construction scheme.
For small and medium-sized steel structure sports venues, a prestressed construction technology is proposed to reduce the impact of the construction process on the structural state and to fully utilize the characteristics of the steel structure itself, which has a certain elastic deformation range. The main feature of the process is to first construct the main truss, followed by the roof grid. After the main truss is completed, it is pulled down to a specific position (within its elastic range) using a pull-down cable, and the roof grid is connected to it. After all connections are completed, the tension in the pull-down cable is gradually released in stages. After the pull-down cable tension is released, the main truss experiences a certain degree of rebound. During this process, the roof grid forms a prestressed structure, and a stable whole is formed between the main truss and the roof. A numerical simulation was performed to analyze the construction process and determine the optimal prestressed construction scheme.
