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Steel Construction Published the List of Highly Influential Articles of 2020
2026 Vol. 41, No. 10
Display Method:
2026, 41(10): 1-11.
doi: 10.13206/j.gjgS26082945
Abstract
Abstract:
Steel structure fabrication and erection are characterized by large component dimensions， a high degree of non-standardization， small-batch and high-variety production， pronounced assembly deviations and welding-induced thermal deformation， a high proportion of multi-layer and multi-pass welds in thick plates， and substantial differences between factory fabrication and on-site erection conditions. Consequently， teach-and-playback welding robots， which have been widely adopted in repetitive manufacturing industries such as the automotive industry， cannot be directly transferred to steel structure applications. To clarify the current technological stage， applicable scenarios， and future development directions of welding robots for steel structures， this paper reviews representative application scenarios， including steel bridge panel units， factory fabrication of building steel structures， complex thick-plate joints， and on-site erection， following the logical sequence of technological evolution， engineering applications， key enabling technologies， constraints， and development trends. Recent advances in digital model-driven methods， three-dimensional vision， point cloud recognition， adaptive multi-layer and multi-pass welding， digital twins， and mobile and collaborative robots are also comprehensively analyzed. The review shows that relatively mature dedicated equipment and robotic automation systems have been developed for regular and highly repetitive factory fabrication scenarios， such as steel bridge U-rib panel units and diaphragms. Welding of H-shaped， box-shaped， and stiffened members in building steel structure fabrication is evolving from offline programming toward BIM- and CAD-model-driven operation， three-dimensional vision-based recognition， and teaching-free welding. However， complex non-standard joints， thick-plate multi-layer and multi-pass welding， and on-site operations at height or in confined spaces remain major challenges to the large-scale deployment of welding robots. The current technological focus has expanded from simply improving robotic repeatability to online perception of the actual component state， groove variations， thermal deformation， and weld-bead formation， as well as closed-loop decision-making for welding sequence， bead arrangement， process parameters， and weld quality. The technological pathways for robotic welding of steel structures are shifting from relying primarily on component standardization to reduce operational complexity toward enhancing adaptability to non-standard steel structures through improved perception， planning， and adaptive capabilities， while the two pathways are expected to coexist for an extended period. Future research and applications are likely to place greater emphasis on the integration of models， data， and welding knowledge； multimodal quality perception； autonomous mobility， human–robot collaboration， and multi-robot parallel operation； and task understanding， knowledge retrieval， and continual learning enabled by large-scale AI models and embodied intelligence. Nevertheless， welding process constraints， quality verification， data standards， and safety certification will remain fundamental boundaries for the engineering applications of autonomous welding systems.
Steel structure fabrication and erection are characterized by large component dimensions， a high degree of non-standardization， small-batch and high-variety production， pronounced assembly deviations and welding-induced thermal deformation， a high proportion of multi-layer and multi-pass welds in thick plates， and substantial differences between factory fabrication and on-site erection conditions. Consequently， teach-and-playback welding robots， which have been widely adopted in repetitive manufacturing industries such as the automotive industry， cannot be directly transferred to steel structure applications. To clarify the current technological stage， applicable scenarios， and future development directions of welding robots for steel structures， this paper reviews representative application scenarios， including steel bridge panel units， factory fabrication of building steel structures， complex thick-plate joints， and on-site erection， following the logical sequence of technological evolution， engineering applications， key enabling technologies， constraints， and development trends. Recent advances in digital model-driven methods， three-dimensional vision， point cloud recognition， adaptive multi-layer and multi-pass welding， digital twins， and mobile and collaborative robots are also comprehensively analyzed. The review shows that relatively mature dedicated equipment and robotic automation systems have been developed for regular and highly repetitive factory fabrication scenarios， such as steel bridge U-rib panel units and diaphragms. Welding of H-shaped， box-shaped， and stiffened members in building steel structure fabrication is evolving from offline programming toward BIM- and CAD-model-driven operation， three-dimensional vision-based recognition， and teaching-free welding. However， complex non-standard joints， thick-plate multi-layer and multi-pass welding， and on-site operations at height or in confined spaces remain major challenges to the large-scale deployment of welding robots. The current technological focus has expanded from simply improving robotic repeatability to online perception of the actual component state， groove variations， thermal deformation， and weld-bead formation， as well as closed-loop decision-making for welding sequence， bead arrangement， process parameters， and weld quality. The technological pathways for robotic welding of steel structures are shifting from relying primarily on component standardization to reduce operational complexity toward enhancing adaptability to non-standard steel structures through improved perception， planning， and adaptive capabilities， while the two pathways are expected to coexist for an extended period. Future research and applications are likely to place greater emphasis on the integration of models， data， and welding knowledge； multimodal quality perception； autonomous mobility， human–robot collaboration， and multi-robot parallel operation； and task understanding， knowledge retrieval， and continual learning enabled by large-scale AI models and embodied intelligence. Nevertheless， welding process constraints， quality verification， data standards， and safety certification will remain fundamental boundaries for the engineering applications of autonomous welding systems.
2026, 41(10): 12-20.
doi: 10.13206/j.gjgS26080701
Abstract:
The Jiangmen Underground Neutrino Observatory （JUNO） is a next-generation large-scale liquid scintillator detector led by China. It aims to precisely determine the neutrino mass ordering and conduct cutting-edge research across multiple fields using a 20000-ton liquid scintillator target. To meet the stringent requirements of the central detector regarding its massive scale， ultra-high precision， and extremely low radioactive background， this project innovatively proposed a novel two-layer nested detector configuration consisting of a single-layer stainless steel reticulated shell and an acrylic sphere. This configuration utilizes pure water instead of white oil as the shielding medium and replaces the traditional closed spherical shell with a reticulated shell， achieving a cost-effective leap from kiloton-scale to ten-thousand-ton-scale liquid scintillator detectors. This paper focuses on the key structural design technologies of the central detector. 1） To address the mechanical challenges of the acrylic sphere under immense buoyancy， a load effect adjustment method was proposed. By optimizing the elevation difference between the internal and external liquid levels and developing a spatial hinge whose axial stiffness can be adjusted to regulate the strut forces， the internal forces of the struts were strictly maintained within safe limits. 2） To resolve the issue of overall structural stability， a hinged-rigid conversion joint was designed to effectively enhance the anti-rotational stiffness of the acrylic sphere. Nonlinear analysis demonstrated that the structure exhibited a high stability coefficient. 3） The challenge of connecting heterogeneous materials with vastly different properties （acrylic and stainless steel） was overcome by developing a high-strength hinged joint with an embedded stainless steel ring. Full-scale model tests verified that its ultimate bearing capacity was more than six times the design load. 4） A refined model encompassing the surrounding rock， the structure， and the fluid was established. A two-stage analysis method was employed to conduct seismic response analysis considering fluid-structure interaction （FSI） in underground spaces， confirming the seismic safety of the system. Finally， a replacement filling method for the liquid scintillator was proposed. By synchronously controlling the liquid level difference and medium displacement， the structural safety throughout the entire filling process was ensured.
The Jiangmen Underground Neutrino Observatory （JUNO） is a next-generation large-scale liquid scintillator detector led by China. It aims to precisely determine the neutrino mass ordering and conduct cutting-edge research across multiple fields using a 20000-ton liquid scintillator target. To meet the stringent requirements of the central detector regarding its massive scale， ultra-high precision， and extremely low radioactive background， this project innovatively proposed a novel two-layer nested detector configuration consisting of a single-layer stainless steel reticulated shell and an acrylic sphere. This configuration utilizes pure water instead of white oil as the shielding medium and replaces the traditional closed spherical shell with a reticulated shell， achieving a cost-effective leap from kiloton-scale to ten-thousand-ton-scale liquid scintillator detectors. This paper focuses on the key structural design technologies of the central detector. 1） To address the mechanical challenges of the acrylic sphere under immense buoyancy， a load effect adjustment method was proposed. By optimizing the elevation difference between the internal and external liquid levels and developing a spatial hinge whose axial stiffness can be adjusted to regulate the strut forces， the internal forces of the struts were strictly maintained within safe limits. 2） To resolve the issue of overall structural stability， a hinged-rigid conversion joint was designed to effectively enhance the anti-rotational stiffness of the acrylic sphere. Nonlinear analysis demonstrated that the structure exhibited a high stability coefficient. 3） The challenge of connecting heterogeneous materials with vastly different properties （acrylic and stainless steel） was overcome by developing a high-strength hinged joint with an embedded stainless steel ring. Full-scale model tests verified that its ultimate bearing capacity was more than six times the design load. 4） A refined model encompassing the surrounding rock， the structure， and the fluid was established. A two-stage analysis method was employed to conduct seismic response analysis considering fluid-structure interaction （FSI） in underground spaces， confirming the seismic safety of the system. Finally， a replacement filling method for the liquid scintillator was proposed. By synchronously controlling the liquid level difference and medium displacement， the structural safety throughout the entire filling process was ensured.
2026, 41(10): 21-29.
Abstract:
To meet the demands of industrialized construction and the “dual carbon” strategy， and to promote high-strength structures and resource utilization of solid waste while expanding the application of concrete-filled steel tubes （CFSTs） to more fields such as marine engineering， recent studies have focused on high-strength CFSTs and prefabricated steel-tube solid waste concrete structural systems. Investigations on beams， columns， and shear walls under various loading conditions have led to a novel prefabricated system that integrates high performance with solid waste utilization. This review summarizes progress in the behavior of high-strength CFST components under static， seismic， fire， and post-fire conditions； corrosion mechanisms and protection measures； FRP strengthening and composite confinement techniques； and sustainable materials including tailings sand and recycled aggregates. It also covers structural systems such as double-steel-plate composite shear walls， buckling-restrained steel-plate shear walls， and trussed column frames， as well as collapse resistance. These findings confirm that bearing capacity theories， FRP confinement mechanisms， and constitutive models for solid waste-based concrete are well developed， and that these structural systems demonstrate excellent mechanical performance.
To meet the demands of industrialized construction and the “dual carbon” strategy， and to promote high-strength structures and resource utilization of solid waste while expanding the application of concrete-filled steel tubes （CFSTs） to more fields such as marine engineering， recent studies have focused on high-strength CFSTs and prefabricated steel-tube solid waste concrete structural systems. Investigations on beams， columns， and shear walls under various loading conditions have led to a novel prefabricated system that integrates high performance with solid waste utilization. This review summarizes progress in the behavior of high-strength CFST components under static， seismic， fire， and post-fire conditions； corrosion mechanisms and protection measures； FRP strengthening and composite confinement techniques； and sustainable materials including tailings sand and recycled aggregates. It also covers structural systems such as double-steel-plate composite shear walls， buckling-restrained steel-plate shear walls， and trussed column frames， as well as collapse resistance. These findings confirm that bearing capacity theories， FRP confinement mechanisms， and constitutive models for solid waste-based concrete are well developed， and that these structural systems demonstrate excellent mechanical performance.
2026, 41(10): 30-38.
doi: 10.13206/j.gjgS26030901
Abstract:
Seismic action and seismic safety evaluation are essential in the current design standards for building steel structures in both China and the U.S. Both Chinese and U.S. standards specify the seismic design requirements for building structures， the selection of ground motion parameters， methods for calculating seismic action， seismic systems for steel structures， and seismic safety evaluation methods for steel members and joints. This paper summarizes the relevant technical standards for seismic design of building steel structures in China and the U.S.， and analyzes and compares certain provisions. The aim is to improve the understanding of seismic design requirements in both countries and to provide a reference for revising relevant provisions in Chinese standards.
Seismic action and seismic safety evaluation are essential in the current design standards for building steel structures in both China and the U.S. Both Chinese and U.S. standards specify the seismic design requirements for building structures， the selection of ground motion parameters， methods for calculating seismic action， seismic systems for steel structures， and seismic safety evaluation methods for steel members and joints. This paper summarizes the relevant technical standards for seismic design of building steel structures in China and the U.S.， and analyzes and compares certain provisions. The aim is to improve the understanding of seismic design requirements in both countries and to provide a reference for revising relevant provisions in Chinese standards.
2026, 41(10): 39-44.
doi: 10.13206/j.gjgS26082746
Abstract:
The pressurization load of pressurized steel structure buildings exhibits particular characteristics， such as high standard values， long duration， and amplitude fluctuations. Its variability and combined effects are key factors affecting structural reliability. Under the premise of ensuring structural reliability， various combinations of primary and secondary loads were compared through long-period load measurements. A design method for pressurized building structures guided by the ultimate pressurization load （bounded action） was proposed. Based on the residual pressure control method， an evaluation index and method for the air-tightness of pressurized steel structure buildings were proposed. Through a series of static air-tightness tests on individual building modules （including connecting components）， an indicator termed the equivalent pressure relief area was obtained. The results indicate that the overall air-tightness of pressurized buildings is superior to that of aircraft.
The pressurization load of pressurized steel structure buildings exhibits particular characteristics， such as high standard values， long duration， and amplitude fluctuations. Its variability and combined effects are key factors affecting structural reliability. Under the premise of ensuring structural reliability， various combinations of primary and secondary loads were compared through long-period load measurements. A design method for pressurized building structures guided by the ultimate pressurization load （bounded action） was proposed. Based on the residual pressure control method， an evaluation index and method for the air-tightness of pressurized steel structure buildings were proposed. Through a series of static air-tightness tests on individual building modules （including connecting components）， an indicator termed the equivalent pressure relief area was obtained. The results indicate that the overall air-tightness of pressurized buildings is superior to that of aircraft.
2026, 41(10): 45-51.
doi: 10.13206/j.gjgS26081745
Abstract:
A direct analysis method is proposed for high-strength steel members and frames by explicitly incorporating residual-stress models. The method combines a quasi-Newton cross-sectional analysis procedure with residual-stress distributions for welded box and H-shaped sections. A curved arbitrarily located hinge （ALH） element is adopted to represent initial geometric imperfections， P-Δ and P-δ effects， and nonlinear responses developing along the member length. A plastic fiber hinge model driven by iterative cross-sectional strength surfaces is then used to update the hinge stiffness from initial yielding to ultimate failure. Verification examples involving box sections， welded H-section columns， and a two-story space frame show that， with residual stresses and initial geometric imperfections explicitly considered， the calculated yield surfaces， ultimate bearing capacities， and load-displacement curves agree well with existing experimental or finite-element results. The proposed procedure provides an effective numerical tool for stability design of high-strength steel structures.
A direct analysis method is proposed for high-strength steel members and frames by explicitly incorporating residual-stress models. The method combines a quasi-Newton cross-sectional analysis procedure with residual-stress distributions for welded box and H-shaped sections. A curved arbitrarily located hinge （ALH） element is adopted to represent initial geometric imperfections， P-Δ and P-δ effects， and nonlinear responses developing along the member length. A plastic fiber hinge model driven by iterative cross-sectional strength surfaces is then used to update the hinge stiffness from initial yielding to ultimate failure. Verification examples involving box sections， welded H-section columns， and a two-story space frame show that， with residual stresses and initial geometric imperfections explicitly considered， the calculated yield surfaces， ultimate bearing capacities， and load-displacement curves agree well with existing experimental or finite-element results. The proposed procedure provides an effective numerical tool for stability design of high-strength steel structures.
2026, 41(10): 52-64.
doi: 10.13206/j.gjgS26091245
Abstract:
At present， the global construction and infrastructure industry is rapidly transforming toward green， low-carbon， efficient， intensive， and intelligent operations. As a core component of modern infrastructure， steel structures serve as a pivotal driver for implementing the “carbon neutrality” strategy and advancing the modernization of the construction industry. Chinese high-strength steel grades such as Q690 and Q960 offer superior strength-to-weight ratios， high material efficiency， and low-carbon and energy-saving benefits， making them the preferred choices for large-scale， long-span， and lightweight infrastructure projects in the new era. However， for a long time， three major challenges have hindered the large-scale and international application of high-strength steel： the lack of unified international design standards， the technical complexity of welding high-strength steel， and conservative design methods. Consequently， its exceptional benefits and potential have not been fully realized. This paper systematically reviews major achievements， of the Chinese National Engineering Research Center for Steel Construction （Hong Kong Branch； CNERC）， including research and development， optimization of manufacturing processes， alignment with international standards， and the construction of landmark projects. This paper comprehensively shows the innovative breakthroughs and engineering applications of Chinese high-strength steel structures， and looks ahead to the future of the steel industry， so as to provide valuable experience for the upgrading of the Chinese steel structure industry and the export of Chinese steel structures worldwide.
At present， the global construction and infrastructure industry is rapidly transforming toward green， low-carbon， efficient， intensive， and intelligent operations. As a core component of modern infrastructure， steel structures serve as a pivotal driver for implementing the “carbon neutrality” strategy and advancing the modernization of the construction industry. Chinese high-strength steel grades such as Q690 and Q960 offer superior strength-to-weight ratios， high material efficiency， and low-carbon and energy-saving benefits， making them the preferred choices for large-scale， long-span， and lightweight infrastructure projects in the new era. However， for a long time， three major challenges have hindered the large-scale and international application of high-strength steel： the lack of unified international design standards， the technical complexity of welding high-strength steel， and conservative design methods. Consequently， its exceptional benefits and potential have not been fully realized. This paper systematically reviews major achievements， of the Chinese National Engineering Research Center for Steel Construction （Hong Kong Branch； CNERC）， including research and development， optimization of manufacturing processes， alignment with international standards， and the construction of landmark projects. This paper comprehensively shows the innovative breakthroughs and engineering applications of Chinese high-strength steel structures， and looks ahead to the future of the steel industry， so as to provide valuable experience for the upgrading of the Chinese steel structure industry and the export of Chinese steel structures worldwide.
2026, 41(10): 65-72.
doi: 10.13206/j.gjgS26070901
Abstract:
Centering on landmark steel structure projects in Beijing and incorporating technological advances in similar projects nationwide， this paper systematically examines the stage-specific characteristics and iteration patterns of construction technologies for long-span steel structures in China. The development process is divided into four stages： the initial foundation stage （1950-1980）， i.e.， the formation period of manual and simple construction systems； the standardization and shaping stage （1980-1999）， i.e.， the popularization period of space grid structures and mechanized construction； the irregular-form breakthrough stage （2000-2010）， i.e.， the innovation period of complex spatial steel structures and high-strength steel； and the intelligent and lightweight maturity stage （2010-）， i.e.， the leading period of flexible structures and digital intelligent construction. On this basis， the paper reveals the patterns of technological iteration in each stage from the perspectives of structural system， construction method， joining technology， and quality control， aiming to provide theoretical support and practical reference for the innovation of intelligent construction technologies for ultra-large and ultra-complex steel structures.
Centering on landmark steel structure projects in Beijing and incorporating technological advances in similar projects nationwide， this paper systematically examines the stage-specific characteristics and iteration patterns of construction technologies for long-span steel structures in China. The development process is divided into four stages： the initial foundation stage （1950-1980）， i.e.， the formation period of manual and simple construction systems； the standardization and shaping stage （1980-1999）， i.e.， the popularization period of space grid structures and mechanized construction； the irregular-form breakthrough stage （2000-2010）， i.e.， the innovation period of complex spatial steel structures and high-strength steel； and the intelligent and lightweight maturity stage （2010-）， i.e.， the leading period of flexible structures and digital intelligent construction. On this basis， the paper reveals the patterns of technological iteration in each stage from the perspectives of structural system， construction method， joining technology， and quality control， aiming to provide theoretical support and practical reference for the innovation of intelligent construction technologies for ultra-large and ultra-complex steel structures.
2026, 41(10): 73-83.
doi: 10.13206/j.gjgS26073101
Abstract:
With the continued advancement of construction industrialization， modular buildings have been widely adopted worldwide owing to their high degree of prefabrication， rapid construction， reduced on-site operation， and environmental sustainability. Among these systems， modular steel buildings are assembled from modular steel units through inter-module connections and offer the advantages of high strength-to-weight ratio and suitability for industrialized production. Extensive studies have been conducted on inter-module connections， modular steel units， and modular steel building systems. On this basis， this paper systematically reviews the research progress at these three levels. The structural configurations and mechanical properties of different types of inter-module connections are summarized； the mechanical behaviors and failure modes of various modular steel units are reviewed； and the static load-carrying performance and dynamic seismic performance of modular steel building systems are examined. Future research directions for modular steel buildings are also proposed.
With the continued advancement of construction industrialization， modular buildings have been widely adopted worldwide owing to their high degree of prefabrication， rapid construction， reduced on-site operation， and environmental sustainability. Among these systems， modular steel buildings are assembled from modular steel units through inter-module connections and offer the advantages of high strength-to-weight ratio and suitability for industrialized production. Extensive studies have been conducted on inter-module connections， modular steel units， and modular steel building systems. On this basis， this paper systematically reviews the research progress at these three levels. The structural configurations and mechanical properties of different types of inter-module connections are summarized； the mechanical behaviors and failure modes of various modular steel units are reviewed； and the static load-carrying performance and dynamic seismic performance of modular steel building systems are examined. Future research directions for modular steel buildings are also proposed.
2026, 41(10): 84-94.
doi: 10.13206/j.gjgS26070801
Abstract:
Classical structural stability theory generally categorizes structural （member） buckling into two types： bifurcation buckling and limit-point buckling. In bifurcation buckling， multiple equilibrium paths coexist at the critical point， whereas in limit-point buckling， the deformation mode remains unchanged before and after buckling. These two types correspond to ideal conditions and cases with initial geometric imperfections， respectively. However， studies on ideal cold-formed C-section steel members under strong-axis eccentric compression have shown that， after local buckling occurs， the member undergoes an abrupt deformation mode change and follows a unique deformation path. This behavior is distinctly different from both bifurcation buckling and limit-point buckling and represents a typical case of non-bifurcation buckling associated with abrupt deformation mode change. To accurately investigate this buckling behavior in cold-formed C-section steel members under strong-axis eccentric compression， this study adopted a combined approach using three-dimensional scanning technology and finite element simulation. The full-range mechanical responses of both ideal members and members with initial geometric imperfections were analyzed， and the influence of initial geometric imperfections on this buckling mode was thoroughly examined. The results indicated that， compared with ideal members， the neutral axis of imperfect members underwent a slight rotation during the early stages of loading. Regardless of whether imperfections were present， once the neutral axis began to rotate， its rotation angle continued to increase with increasing load. The triggering mechanism for the non-bifurcation buckling associated with abrupt deformation mode change in cold-formed C-section steel members under strong-axis eccentric compression was local buckling， which induced stress redistribution across the cross-section， leading to rotation of the neutral axis and overall torsional deformation of the member.
Classical structural stability theory generally categorizes structural （member） buckling into two types： bifurcation buckling and limit-point buckling. In bifurcation buckling， multiple equilibrium paths coexist at the critical point， whereas in limit-point buckling， the deformation mode remains unchanged before and after buckling. These two types correspond to ideal conditions and cases with initial geometric imperfections， respectively. However， studies on ideal cold-formed C-section steel members under strong-axis eccentric compression have shown that， after local buckling occurs， the member undergoes an abrupt deformation mode change and follows a unique deformation path. This behavior is distinctly different from both bifurcation buckling and limit-point buckling and represents a typical case of non-bifurcation buckling associated with abrupt deformation mode change. To accurately investigate this buckling behavior in cold-formed C-section steel members under strong-axis eccentric compression， this study adopted a combined approach using three-dimensional scanning technology and finite element simulation. The full-range mechanical responses of both ideal members and members with initial geometric imperfections were analyzed， and the influence of initial geometric imperfections on this buckling mode was thoroughly examined. The results indicated that， compared with ideal members， the neutral axis of imperfect members underwent a slight rotation during the early stages of loading. Regardless of whether imperfections were present， once the neutral axis began to rotate， its rotation angle continued to increase with increasing load. The triggering mechanism for the non-bifurcation buckling associated with abrupt deformation mode change in cold-formed C-section steel members under strong-axis eccentric compression was local buckling， which induced stress redistribution across the cross-section， leading to rotation of the neutral axis and overall torsional deformation of the member.
2026, 41(10): 95-106.
doi: 10.13206/j.gjgS26081145
Abstract:
To address the increased in-plane depth of excavation-side bracing， restricted working space along the pit perimeter， and limited interchangeability of structural members resulting from increased bracing spans in large-scale foundation pits， a long-span nested double beam-string steel bracing system is proposed. The bracing system consists of inner and outer beam-string units， with the crown beam or waler serving as their common upper-chord beam-column member. The beam-string units provide zoned support， with the bracing span adjusted by varying the horizontal tension-rod lengths while keeping the strut lengths and in-plane installation heights unchanged， thereby facilitating modular and standardized member design. Compared with the ZXL36 single beam-string bracing system with the same span of 36 m， the proposed system reduces the maximum in-plane depth from 9.113 m to 8.000 m， a reduction of 12.2%， while reducing the numbers of both struts and active displacement-control devices from five to four. A three-dimensional finite element model of a 40 m-span nested double beam-string steel bracing system was developed to investigate its structural response to prestressing and equivalent earth pressure. The effects of solar radiation and uniform temperature variation on the structural behavior of the bracing system were examined. For the 40 m-span system subjected to a resultant equivalent earth-pressure force of 25000 kN， prestressing established an initial tension-compression state， with the steel tension rods in tension and the struts in compression. Prestressing also produced an active in-plane pre-deformation of 63.6 mm toward the outside of the foundation pit at the midspan of the common upper-chord member. As the earth pressure was applied， the in-plane displacement increment toward the inside of the foundation pit at the midspan of this member reached 67.1 mm. The outward pre-deformation induced by prestressing offset most of the earth-pressure-induced displacement， resulting in a final inward in-plane displacement of only 3.5 mm. The axial forces in the inclined tension rods， horizontal tension rods， and compression struts of the outer beam-string unit were 14125 kN， 9987 kN， and -11066 kN， respectively， whereas the corresponding values in the inner unit were 7467 kN， 5618 kN， and -4947 kN. The axial-force levels in the outer unit were higher than those in the inner unit. The maximum cross-sectional von Mises stresses of the members ranged from 157 to 409 MPa. The outer inclined tension rod exhibited the highest stress of 409 MPa and was therefore the strength-governing member under this loading condition. Under solar radiation， the absolute axial forces in the main members of the inner and outer beam-string units decreased by 10.2%-10.3% and approximately 25.9%， respectively， relative to those under the equivalent earth-pressure condition at ambient temperature； the maximum cross-sectional Mises stresses of these members decreased by 2.5%-10.1% and 18.5%-27.1%， respectively.Nonuniform heating produced a pronounced stress gradient across the strut sections， while the thermal elongation of the steel tension rods caused a loss of effective prestress. Consequently， the inward in-plane displacement at the midspan of the common upper-chord member increased from 3.5 mm to 76.5 mm， exceeding the allowable limit of 30 mm. In engineering applications， the in-plane displacement of the bracing system and the prestress levels in its members should therefore be monitored， and the prestress should be adjusted promptly based on the monitoring results to satisfy the displacement-control requirements. Following a uniform temperature decrease of 15 ℃， the midspan displacement of the common upper-chord member changed from an inward displacement of 3.5 mm to an outward displacement of 1.8 mm. The absolute axial forces in the main members of the inner and outer beam-string units increased by 1.2%-1.3% and 1.5%-1.6%， respectively， while the maximum cross-sectional Mises stresses increased by 2.1%-3.7%. These results indicated that the uniform temperature decrease had only a limited effect on the internal forces and stresses of the structural members.
To address the increased in-plane depth of excavation-side bracing， restricted working space along the pit perimeter， and limited interchangeability of structural members resulting from increased bracing spans in large-scale foundation pits， a long-span nested double beam-string steel bracing system is proposed. The bracing system consists of inner and outer beam-string units， with the crown beam or waler serving as their common upper-chord beam-column member. The beam-string units provide zoned support， with the bracing span adjusted by varying the horizontal tension-rod lengths while keeping the strut lengths and in-plane installation heights unchanged， thereby facilitating modular and standardized member design. Compared with the ZXL36 single beam-string bracing system with the same span of 36 m， the proposed system reduces the maximum in-plane depth from 9.113 m to 8.000 m， a reduction of 12.2%， while reducing the numbers of both struts and active displacement-control devices from five to four. A three-dimensional finite element model of a 40 m-span nested double beam-string steel bracing system was developed to investigate its structural response to prestressing and equivalent earth pressure. The effects of solar radiation and uniform temperature variation on the structural behavior of the bracing system were examined. For the 40 m-span system subjected to a resultant equivalent earth-pressure force of 25000 kN， prestressing established an initial tension-compression state， with the steel tension rods in tension and the struts in compression. Prestressing also produced an active in-plane pre-deformation of 63.6 mm toward the outside of the foundation pit at the midspan of the common upper-chord member. As the earth pressure was applied， the in-plane displacement increment toward the inside of the foundation pit at the midspan of this member reached 67.1 mm. The outward pre-deformation induced by prestressing offset most of the earth-pressure-induced displacement， resulting in a final inward in-plane displacement of only 3.5 mm. The axial forces in the inclined tension rods， horizontal tension rods， and compression struts of the outer beam-string unit were 14125 kN， 9987 kN， and -11066 kN， respectively， whereas the corresponding values in the inner unit were 7467 kN， 5618 kN， and -4947 kN. The axial-force levels in the outer unit were higher than those in the inner unit. The maximum cross-sectional von Mises stresses of the members ranged from 157 to 409 MPa. The outer inclined tension rod exhibited the highest stress of 409 MPa and was therefore the strength-governing member under this loading condition. Under solar radiation， the absolute axial forces in the main members of the inner and outer beam-string units decreased by 10.2%-10.3% and approximately 25.9%， respectively， relative to those under the equivalent earth-pressure condition at ambient temperature； the maximum cross-sectional Mises stresses of these members decreased by 2.5%-10.1% and 18.5%-27.1%， respectively.Nonuniform heating produced a pronounced stress gradient across the strut sections， while the thermal elongation of the steel tension rods caused a loss of effective prestress. Consequently， the inward in-plane displacement at the midspan of the common upper-chord member increased from 3.5 mm to 76.5 mm， exceeding the allowable limit of 30 mm. In engineering applications， the in-plane displacement of the bracing system and the prestress levels in its members should therefore be monitored， and the prestress should be adjusted promptly based on the monitoring results to satisfy the displacement-control requirements. Following a uniform temperature decrease of 15 ℃， the midspan displacement of the common upper-chord member changed from an inward displacement of 3.5 mm to an outward displacement of 1.8 mm. The absolute axial forces in the main members of the inner and outer beam-string units increased by 1.2%-1.3% and 1.5%-1.6%， respectively， while the maximum cross-sectional Mises stresses increased by 2.1%-3.7%. These results indicated that the uniform temperature decrease had only a limited effect on the internal forces and stresses of the structural members.
2026, 41(10): 107-116.
doi: 10.13206/j.gjgS26080301
Abstract:
The sheave platform beam is a key load-bearing component in coal mine vertical shaft headframes. To reveal the influence mechanism of randomly initiated and locally penetrating pitting damage on its mechanical properties， a box-section sheave platform beam of a vertical shaft headframe in a Henan coal mine was investigated. Based on ANSYS software， a finite element analysis model of the structure was established， and the validity of the numerical model was verified against experimental data. On this basis， the influence of the depth， width， and aspect ratio of pitting pits on the stress concentration factor was discussed， and the influence mechanism of pit width and its distribution along the length and width directions of the beam on the ultimate bearing capacity of the structure was further studied. The results showed that the stress concentration factor of the structure was greatly affected by the geometric parameters of the pitting pits； the local stiffness of the pitted area increased with increasing pit width； when the structure was in the elastic stage， the distribution positions of the pitting pits along the length and width directions of the beam had a minor impact on the structural stiffness； after entering the plastic stage， the change in pitting pit position along the width direction had a relatively larger impact on the ultimate bearing capacity of the structure， with the maximum loss rate reaching 3.32%， corresponding to approximately 1042 kN.
The sheave platform beam is a key load-bearing component in coal mine vertical shaft headframes. To reveal the influence mechanism of randomly initiated and locally penetrating pitting damage on its mechanical properties， a box-section sheave platform beam of a vertical shaft headframe in a Henan coal mine was investigated. Based on ANSYS software， a finite element analysis model of the structure was established， and the validity of the numerical model was verified against experimental data. On this basis， the influence of the depth， width， and aspect ratio of pitting pits on the stress concentration factor was discussed， and the influence mechanism of pit width and its distribution along the length and width directions of the beam on the ultimate bearing capacity of the structure was further studied. The results showed that the stress concentration factor of the structure was greatly affected by the geometric parameters of the pitting pits； the local stiffness of the pitted area increased with increasing pit width； when the structure was in the elastic stage， the distribution positions of the pitting pits along the length and width directions of the beam had a minor impact on the structural stiffness； after entering the plastic stage， the change in pitting pit position along the width direction had a relatively larger impact on the ultimate bearing capacity of the structure， with the maximum loss rate reaching 3.32%， corresponding to approximately 1042 kN.
