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Steel Construction Published the List of Highly Influential Articles of 2020
Current Issue
2026 Vol. 41, No. 5
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2026, 41(5): 1-7.
doi: 10.13206/j.gjgS25102901
Abstract
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Abstract:
For coatings that serve as protective barriers for steel structures， their adhesion strength is a core indicator determining protective efficiency and service life. This paper reviews the research progress on the bonding performance of organic protective coatings for steel structures， analyzes the factors influencing the evolution of bonding performance and their respective mechanisms， summarizes the testing methods for coating bonding performance， and elaborates on the construction and application of interface cohesive models. The analysis shows that the variation mechanisms induced by single factors have currently been revealed， and the existing interface constitutive models focus on the interface damage and fracture behavior under the action of force fields.In the future， it is necessary to further study the coupled action mechanisms and influence patterns of multiple factors， and to construct an interface behavior prediction model that considers the coupling of multiple factors （environmental conditions， fire high temperatures， and stress）， so as to provide references for the design， damage detection， and performance repair of protective coatings for steel structures.
For coatings that serve as protective barriers for steel structures， their adhesion strength is a core indicator determining protective efficiency and service life. This paper reviews the research progress on the bonding performance of organic protective coatings for steel structures， analyzes the factors influencing the evolution of bonding performance and their respective mechanisms， summarizes the testing methods for coating bonding performance， and elaborates on the construction and application of interface cohesive models. The analysis shows that the variation mechanisms induced by single factors have currently been revealed， and the existing interface constitutive models focus on the interface damage and fracture behavior under the action of force fields.In the future， it is necessary to further study the coupled action mechanisms and influence patterns of multiple factors， and to construct an interface behavior prediction model that considers the coupling of multiple factors （environmental conditions， fire high temperatures， and stress）， so as to provide references for the design， damage detection， and performance repair of protective coatings for steel structures.
2026, 41(5): 8-23.
doi: 10.13206/j.gjgS25011101
Abstract:
Steel-concrete composite structures have been widely used in multi-story， long-span， and heavy-load buildings due to their advantages of high strength， high stiffness， excellent seismic performance， and construction efficiency. With the rising frequency of building fires， which pose significant threats to life and property， investigating the fire resistance of these structures is imperative. This necessitates developing fire-resistance design methods that consider overall structural performance and implementing corresponding protective measures. The ultimate goal is to ensure the integrity of critical structural components and prevent the collapse of the overall structure， which is of great significance in ensuring the overall fire safety of structures and reducing fire protection costs in construction.This paper summarized the fire resistance of steel-concrete composite structures， focusing on fire experimental studies on steel-concrete composite beams， reinforced concrete （RC） two-way slabs， concrete-filled steel tubular （CFST） columns， as well as the steel-concrete composite planar and spatial frames. Additionally， various fire resistance analysis models were discussed and compared. Based on the review， key issues and future directions were proposed．The main findings were as follows： 1） Experimental studies demonstrated that steel-concrete composite restrained beams exhibited significantly better fire resistance than simply-supported beams， owing to the catenary effect under high temperatures and large deformations. RC two-way slabs showed excellent fire resistance， with observed cracking on the top surface while the bottom remained relatively intact. The fire resistance of conventional CFST columns was found to be limited， requiring protective measures. Moreover， composite spatial frames demonstrated superior performance compared to planar frames， as they maintained structural integrity without collapse， whereas planar frames were prone to beam or column failure. 2） Numerical analysis indicated that the shell-solid element model effectively simulated the local and torsional buckling of steel beams observed in tests of steel-concrete composite continuous and restrained beams. The solid element model accurately reproduced the expansion deformation in reinforced concrete two-way slabs resulting from non-uniform temperature distributions across their thickness. When solid or shell-solid element models were applied to CFST columns， they successfully captured the interface void， slippage， and constraint effects between the steel tube and concrete. Furthermore， modeling concrete with solid elements incorporating its thermo-mechanical-time constitutive relations satisfactorily represented the phenomenon where the top of the RC two-way slabs cracked while the bottom remained largely intact. Similarly， modeling steel using solid or shell elements with its thermo-mechanical constitutive relations， which implicitly incorporated high-temperature creep into the stress-induced strain， the finite element calculated values of deformation for steel-concrete composite beams and CFST columns under fire showed good agreement with experimental values. 3） Due to the limitations of experimental conditions， structural fire tests seldom achieved the collapse stage， leaving the failure mechanisms of structural systems inadequately understood. It was essential to employ shell-solid finite element models combined with thermo-mechanical-（time） constitutive relationships of materials to conduct fire resistance analysis of composite spatial frames and establish the correlation between component failure and structural system failure. Furthermore， the current fire protection design methods based on component testing or calculation， as stipulated in existing codes， still need to be thoroughly investigated to determine whether they meet the requirements for structural fire protection design.
Steel-concrete composite structures have been widely used in multi-story， long-span， and heavy-load buildings due to their advantages of high strength， high stiffness， excellent seismic performance， and construction efficiency. With the rising frequency of building fires， which pose significant threats to life and property， investigating the fire resistance of these structures is imperative. This necessitates developing fire-resistance design methods that consider overall structural performance and implementing corresponding protective measures. The ultimate goal is to ensure the integrity of critical structural components and prevent the collapse of the overall structure， which is of great significance in ensuring the overall fire safety of structures and reducing fire protection costs in construction.This paper summarized the fire resistance of steel-concrete composite structures， focusing on fire experimental studies on steel-concrete composite beams， reinforced concrete （RC） two-way slabs， concrete-filled steel tubular （CFST） columns， as well as the steel-concrete composite planar and spatial frames. Additionally， various fire resistance analysis models were discussed and compared. Based on the review， key issues and future directions were proposed．The main findings were as follows： 1） Experimental studies demonstrated that steel-concrete composite restrained beams exhibited significantly better fire resistance than simply-supported beams， owing to the catenary effect under high temperatures and large deformations. RC two-way slabs showed excellent fire resistance， with observed cracking on the top surface while the bottom remained relatively intact. The fire resistance of conventional CFST columns was found to be limited， requiring protective measures. Moreover， composite spatial frames demonstrated superior performance compared to planar frames， as they maintained structural integrity without collapse， whereas planar frames were prone to beam or column failure. 2） Numerical analysis indicated that the shell-solid element model effectively simulated the local and torsional buckling of steel beams observed in tests of steel-concrete composite continuous and restrained beams. The solid element model accurately reproduced the expansion deformation in reinforced concrete two-way slabs resulting from non-uniform temperature distributions across their thickness. When solid or shell-solid element models were applied to CFST columns， they successfully captured the interface void， slippage， and constraint effects between the steel tube and concrete. Furthermore， modeling concrete with solid elements incorporating its thermo-mechanical-time constitutive relations satisfactorily represented the phenomenon where the top of the RC two-way slabs cracked while the bottom remained largely intact. Similarly， modeling steel using solid or shell elements with its thermo-mechanical constitutive relations， which implicitly incorporated high-temperature creep into the stress-induced strain， the finite element calculated values of deformation for steel-concrete composite beams and CFST columns under fire showed good agreement with experimental values. 3） Due to the limitations of experimental conditions， structural fire tests seldom achieved the collapse stage， leaving the failure mechanisms of structural systems inadequately understood. It was essential to employ shell-solid finite element models combined with thermo-mechanical-（time） constitutive relationships of materials to conduct fire resistance analysis of composite spatial frames and establish the correlation between component failure and structural system failure. Furthermore， the current fire protection design methods based on component testing or calculation， as stipulated in existing codes， still need to be thoroughly investigated to determine whether they meet the requirements for structural fire protection design.
2026, 41(5): 24-34.
doi: 10.13206/j.gjgS25071201
Abstract:
This paper employed the ABAQUS finite element （FE） software to conduct a three-dimensional shell-solid FE analysis on the fire resistance of steel-concrete composite continuous beams. Based on validation of the FE model， the effects of load ratio， load position ratio， shear connection ratio， and fire protection layer thickness of steel beams on the fire resistance of continuous beams were subsequently investigated. Additionally， the relations between the variation of internal forces and the deformation stages of composite continuous beams under fire were elucidated. It further revealed the mechanical response mechanisms， including the interface slip behavior， the formation of plastic hinges， and the failure modes. Based on these findings， a differentiated fire protection design strategy of “reinforcing the side spans while simplifying the mid-span” was proposed. The analysis results revealed that： 1） The mid-span of the three-span continuous beam underwent four deformation stages： elastic， elastoplastic， plastic， and catenary action. The catenary effect reduced the required thickness of the fire protection layer. As the restraint stiffness decreased， particularly in the edge span of the continuous beam， the failure mode of the beam shifted from overall lateral instability to failure due to insufficient bearing capacity. In such cases， the fire resistance was equivalent to that of a simply-supported beam due to the absence of the catenary effect. 2） Due to the thermal expansion of the composite beam being constrained by the intermediate supports， a large negative bending moment was generated. Consequently， the plastic hinge at the supports formed earlier than that at the mid-span. Additionally， the positive bending moment at the mid-span of the composite continuous beam decreased or even reversed to negative in the early stages of the fire. Throughout the fire exposure， the continuous beam underwent a significant redistribution of internal forces. 3） The fire resistance of the composite continuous beam was almost unaffected by the shear connection degree η. However， when the steel beam had no fire protection， the end slip decreased significantly with increases in η. As the thickness of the fire protection layer increased， the influence of η on the beam-end displacement weakened， and the end slip was markedly reduced. 4） For composite beams with a load ratio of 0.4， a differentiated fire protection strategy was adopted， which was characterized as “reinforcing the side spans while simplifying the mid-span”. Specifically， the fire protection thickness for the side spans was determined in accordance with the calculation method for simply-supported beams stipulated in the GB 51249—2017 Code for Fire Safety of Steel Structures in Buildings. For the mid-span， fire protection could be omitted entirely， or a minimal layer could be applied to mitigate early-stage deflection during a fire.
This paper employed the ABAQUS finite element （FE） software to conduct a three-dimensional shell-solid FE analysis on the fire resistance of steel-concrete composite continuous beams. Based on validation of the FE model， the effects of load ratio， load position ratio， shear connection ratio， and fire protection layer thickness of steel beams on the fire resistance of continuous beams were subsequently investigated. Additionally， the relations between the variation of internal forces and the deformation stages of composite continuous beams under fire were elucidated. It further revealed the mechanical response mechanisms， including the interface slip behavior， the formation of plastic hinges， and the failure modes. Based on these findings， a differentiated fire protection design strategy of “reinforcing the side spans while simplifying the mid-span” was proposed. The analysis results revealed that： 1） The mid-span of the three-span continuous beam underwent four deformation stages： elastic， elastoplastic， plastic， and catenary action. The catenary effect reduced the required thickness of the fire protection layer. As the restraint stiffness decreased， particularly in the edge span of the continuous beam， the failure mode of the beam shifted from overall lateral instability to failure due to insufficient bearing capacity. In such cases， the fire resistance was equivalent to that of a simply-supported beam due to the absence of the catenary effect. 2） Due to the thermal expansion of the composite beam being constrained by the intermediate supports， a large negative bending moment was generated. Consequently， the plastic hinge at the supports formed earlier than that at the mid-span. Additionally， the positive bending moment at the mid-span of the composite continuous beam decreased or even reversed to negative in the early stages of the fire. Throughout the fire exposure， the continuous beam underwent a significant redistribution of internal forces. 3） The fire resistance of the composite continuous beam was almost unaffected by the shear connection degree η. However， when the steel beam had no fire protection， the end slip decreased significantly with increases in η. As the thickness of the fire protection layer increased， the influence of η on the beam-end displacement weakened， and the end slip was markedly reduced. 4） For composite beams with a load ratio of 0.4， a differentiated fire protection strategy was adopted， which was characterized as “reinforcing the side spans while simplifying the mid-span”. Specifically， the fire protection thickness for the side spans was determined in accordance with the calculation method for simply-supported beams stipulated in the GB 51249—2017 Code for Fire Safety of Steel Structures in Buildings. For the mid-span， fire protection could be omitted entirely， or a minimal layer could be applied to mitigate early-stage deflection during a fire.
2026, 41(5): 35-46.
doi: 10.13206/j.gjgS25103001
Abstract:
In existing fire tests on space frames， significant deformations were observed in the components， yet the overall structure did not collapse. Therefore， studying the fire resistance of space frames while taking into account the overall performance of the structure is of paramount importance for ensuring the safety of the entire structure and reducing building fire protection costs. In existing finite element （FE） studies on space frames， beam elements were typically used to model steel columns and beams， which made it difficult to simulate the local buckling behavior of constrained beams and columns. For concrete slabs， shell elements were adopted， but they struggled to capture the expansive deformation induced by the non-uniform temperature field along the thickness direction. In contrast， the aforementioned issues were effectively addressed by employing shell elements for steel beams and solid elements for concrete slabs. Furthermore， in existing FE studies on individual components， when the thermal-mechanical-time constitutive relation was applied to concrete and the thermal-mechanical constitutive relation was used for steel， the FE calculation results for deformation and failure modes agreed more closely with the test results. Therefore， this study adopted an FE model combining shell-solid elements， along with the thermal-mechanical-time constitutive relation for concrete and the thermal-mechanical constitutive relation for steel， to simulate the fire test of the space frame with steel columns and composite floor systems. The FE calculation results for the temperature and deformation of beams， slabs， and columns were in good agreement with the test results. Moreover， the stress contour plot of the concrete slab accurately reflected the test phenomenon where the top surface of the reinforced concrete slab cracked while the bottom remained relatively intact when the slab underwent large deformation under fire. The well-established FE model can provide a solid foundation for subsequent fire resistance analysis of composite space frames and the development of fire resistance design methods.
In existing fire tests on space frames， significant deformations were observed in the components， yet the overall structure did not collapse. Therefore， studying the fire resistance of space frames while taking into account the overall performance of the structure is of paramount importance for ensuring the safety of the entire structure and reducing building fire protection costs. In existing finite element （FE） studies on space frames， beam elements were typically used to model steel columns and beams， which made it difficult to simulate the local buckling behavior of constrained beams and columns. For concrete slabs， shell elements were adopted， but they struggled to capture the expansive deformation induced by the non-uniform temperature field along the thickness direction. In contrast， the aforementioned issues were effectively addressed by employing shell elements for steel beams and solid elements for concrete slabs. Furthermore， in existing FE studies on individual components， when the thermal-mechanical-time constitutive relation was applied to concrete and the thermal-mechanical constitutive relation was used for steel， the FE calculation results for deformation and failure modes agreed more closely with the test results. Therefore， this study adopted an FE model combining shell-solid elements， along with the thermal-mechanical-time constitutive relation for concrete and the thermal-mechanical constitutive relation for steel， to simulate the fire test of the space frame with steel columns and composite floor systems. The FE calculation results for the temperature and deformation of beams， slabs， and columns were in good agreement with the test results. Moreover， the stress contour plot of the concrete slab accurately reflected the test phenomenon where the top surface of the reinforced concrete slab cracked while the bottom remained relatively intact when the slab underwent large deformation under fire. The well-established FE model can provide a solid foundation for subsequent fire resistance analysis of composite space frames and the development of fire resistance design methods.
2026, 41(5): 47-55.
doi: 10.13206/j.gjgS25112601
Abstract:
To achieve efficient connections between modules of modular steel frames，a novel inner sleeve connection joint facilitating onsite fully-bolted assembly is proposed. To investigate the mechanical properties，failure mechanism，and influencing parameters of this novel joint under tensile loading，monotonic tensile tests and finite element analyses were conducted by focusing on its local connection details. Four sets of scaled models were designed for a comparative study on the mechanical peroperty indicators（e. g. ，deformation characteristics，failure modes，and bearing capacity）and the evolution mechanisms of the novel connection structure under tensile conditions. Based on the test data，an ABAQUS finite element model was established to perform parametric analysis on the key parameters of the joint. The research results indicated that the thickness and length of the inner sleeve component had a negligible effect on the tensile performance of the novel joint；variations in the thickness of the angle steel component significantly influenced the yield load and peak load of the novel joint under monotonic tension；the thickness of the connecting plate had a certain impact on the tensile capacity of the novel joint，but the coordinated force and deformation between the connecting plate and the angle steel through high-strength bolts should be taken into account for rational design. Based on the analysis results，practical design suggestions and further optimization directions for this novel fully-bolted connection structure between modules were proposed，providing a theoretical and technical basis for advancing the industrialization of modular steel frame structures and realizing efficient connections between modules.
To achieve efficient connections between modules of modular steel frames，a novel inner sleeve connection joint facilitating onsite fully-bolted assembly is proposed. To investigate the mechanical properties，failure mechanism，and influencing parameters of this novel joint under tensile loading，monotonic tensile tests and finite element analyses were conducted by focusing on its local connection details. Four sets of scaled models were designed for a comparative study on the mechanical peroperty indicators（e. g. ，deformation characteristics，failure modes，and bearing capacity）and the evolution mechanisms of the novel connection structure under tensile conditions. Based on the test data，an ABAQUS finite element model was established to perform parametric analysis on the key parameters of the joint. The research results indicated that the thickness and length of the inner sleeve component had a negligible effect on the tensile performance of the novel joint；variations in the thickness of the angle steel component significantly influenced the yield load and peak load of the novel joint under monotonic tension；the thickness of the connecting plate had a certain impact on the tensile capacity of the novel joint，but the coordinated force and deformation between the connecting plate and the angle steel through high-strength bolts should be taken into account for rational design. Based on the analysis results，practical design suggestions and further optimization directions for this novel fully-bolted connection structure between modules were proposed，providing a theoretical and technical basis for advancing the industrialization of modular steel frame structures and realizing efficient connections between modules.
2026, 41(5): 56-68.
doi: 10.13206/j.gjgS25021501
Abstract:
To mitigate residual deformation of structures under seismic action， a novel self-centering energy-dissipation brace with embedded U-shaped dampers （U-SCEDB） is proposed. The self-centering mechanism employs combined disc springs to provide self-centering capability， while a U-shaped damper serves as the energy dissipation system. Numerical simulations were performed on the brace， and the effects of various design parameters on its hysteretic behavior were systematically evaluated through analysis of the hysteretic curves. The results indicated that the proposed U-SCEDB exhibited stable energy dissipation capacity and superior self-centering capability. Specifically， the energy dissipation capacity and ultimate bearing capacity of the brace increased with the thickness of the U-shaped damper， the length of its straight segment， and the thickness of the energy dissipation plate. Additionally， the self-centering capability was enhanced with a higher pre-tension force applied to the steel strands. Increasing the number of disc spring stacks in series significantly enhanced the ultimate deformability of the brace， but the stiffness of the disc springs decreased relatively.
To mitigate residual deformation of structures under seismic action， a novel self-centering energy-dissipation brace with embedded U-shaped dampers （U-SCEDB） is proposed. The self-centering mechanism employs combined disc springs to provide self-centering capability， while a U-shaped damper serves as the energy dissipation system. Numerical simulations were performed on the brace， and the effects of various design parameters on its hysteretic behavior were systematically evaluated through analysis of the hysteretic curves. The results indicated that the proposed U-SCEDB exhibited stable energy dissipation capacity and superior self-centering capability. Specifically， the energy dissipation capacity and ultimate bearing capacity of the brace increased with the thickness of the U-shaped damper， the length of its straight segment， and the thickness of the energy dissipation plate. Additionally， the self-centering capability was enhanced with a higher pre-tension force applied to the steel strands. Increasing the number of disc spring stacks in series significantly enhanced the ultimate deformability of the brace， but the stiffness of the disc springs decreased relatively.
2026, 41(5): 69-78.
doi: 10.13206/j.gjgS24071002
Abstract:
H-section tapered beams and columns are widely used in steel structure factory buildings because tapered members can maximize material performance by matching the approximately triangular bending moment diagram. The Technical Code for Steel Structure of Light-Weight Buildings with Gabled Frames （GB 51022-2015）， considering the characteristics of light-weight buildings， has made specific provisions for the design of tapered beams and columns， with economy as the primary goal while ensuring safety. Research indicates that major domestic steel structure analysis software adoptes two-dimensional analysis for factory buildings with tapered beams and columns， failing to fully exploit the huge potential of three-dimensional analysis. Based on GB 51022-2015 and PKPM software， this paper briefly presents the analysis methodology for steel structure factory buildings， key points of stability design for tapered members， and analysis examples using mainstream software， thereby proposing a three-dimensional analysis method for factory buildings with H-section tapered beams and columns. Compared with the two-dimensional analysis method， the three-dimensional analysis method demonstrateds broad applicability and high operational efficiency， while also emphasizing the necessity and urgency for users to master knowledge of steel structure stability theory.
H-section tapered beams and columns are widely used in steel structure factory buildings because tapered members can maximize material performance by matching the approximately triangular bending moment diagram. The Technical Code for Steel Structure of Light-Weight Buildings with Gabled Frames （GB 51022-2015）， considering the characteristics of light-weight buildings， has made specific provisions for the design of tapered beams and columns， with economy as the primary goal while ensuring safety. Research indicates that major domestic steel structure analysis software adoptes two-dimensional analysis for factory buildings with tapered beams and columns， failing to fully exploit the huge potential of three-dimensional analysis. Based on GB 51022-2015 and PKPM software， this paper briefly presents the analysis methodology for steel structure factory buildings， key points of stability design for tapered members， and analysis examples using mainstream software， thereby proposing a three-dimensional analysis method for factory buildings with H-section tapered beams and columns. Compared with the two-dimensional analysis method， the three-dimensional analysis method demonstrateds broad applicability and high operational efficiency， while also emphasizing the necessity and urgency for users to master knowledge of steel structure stability theory.
2026, 41(5): 79-83.
doi: 10.13206/j.gjgS25021130
Abstract:
This paper analyzed the flexural-torsional buckling of beam-columns under linearly varying bending moments and axial forces.The Ritz method was adopted， in which both the lateral deflection and the twisting angle were represented by three terms， leading to results close to the exact solutions.The equivalent bending moment coefficient was derived， and new formulas with high accuracy and slight conservativeness were proposed.The results obtained using the proposed formulas in the standard design equations for the out-of-plane stability check of beam-columns were compared with those from current specifications.The results showed that the proposed formulas yielded a slightly higher flexural capacity when stability governed the design.
This paper analyzed the flexural-torsional buckling of beam-columns under linearly varying bending moments and axial forces.The Ritz method was adopted， in which both the lateral deflection and the twisting angle were represented by three terms， leading to results close to the exact solutions.The equivalent bending moment coefficient was derived， and new formulas with high accuracy and slight conservativeness were proposed.The results obtained using the proposed formulas in the standard design equations for the out-of-plane stability check of beam-columns were compared with those from current specifications.The results showed that the proposed formulas yielded a slightly higher flexural capacity when stability governed the design.
2026, 41(5): 84-86.
doi: 10.13206/j.gjgS26050735
Abstract:
This paper introduces the stability problem of axially compressed members using Euler's formula， noting that it is applicable only within the elastic range and mentioning Engesser's tangent modulus theory for non-elastic cases. The derivation process of Euler's formula is also presented. It is pointed out that Euler's formula is based on the small-deflection theory， and a calculation method for the stability bearing capacity of axially compressed members is further developed based on the large-deflection theory. Analysis shows that the Euler critical force obtained using the small-deflection theory is appropriate as the stability capacity.
This paper introduces the stability problem of axially compressed members using Euler's formula， noting that it is applicable only within the elastic range and mentioning Engesser's tangent modulus theory for non-elastic cases. The derivation process of Euler's formula is also presented. It is pointed out that Euler's formula is based on the small-deflection theory， and a calculation method for the stability bearing capacity of axially compressed members is further developed based on the large-deflection theory. Analysis shows that the Euler critical force obtained using the small-deflection theory is appropriate as the stability capacity.
