Login
Register
Submit
Experts Review
Office Work
Author Center
Supervisor: China Iron and Steel Association
Sponsor: Central Research Institute of Building and Construction Co., Ltd., MCC Group, China;China Steel Construction Society，China
Editor-in-Chief: Qingrui Yue
Download:
Call for PapersMore >
Steel Construction Published the List of Highly Influential Articles of 2020
Articles in latest articles have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
Display Method:
Display Method:
2025, 40(2): 1-9.
doi: 10.13206/j.gjgS24092003
Abstract
PDF (6864KB)
Abstract:
Stainless steel, renowned for its excellent aesthetic properties and exceptional corrosion resistance, has found widespread application in structural components such as roofing systems, roof coverings, and curtain walls within architectural engineering. Stainless steel members with C-section have gained prominence due to their high material efficiency and favorable mechanical characteristics. The geometric configuration of these sections enhances the moment of inertia and torsional rigidity of the structural member, while simultaneously minimizing material usage, thereby fulfilling the dual objectives of structural safety and economic viability. However, the complex buckling behaviors and failure mechanisms associated with these sections present significant challenges in their design and analysis. Consequently, the buckling performance of stainless steel members with lipped C-section remains a focal point of ongoing research, with considerable emphasis on understanding and mitigating the associated risks.Up to the present, scholars have categorized the buckling performance of stainless steel members with lipped C-section based on failure modes into two primary types: single-mode buckling (global buckling, local buckling, and distortional buckling) and multi-mode coupled buckling (global-local buckling, global-distortional buckling, local-distortional buckling, and global-local-distortional buckling). The identification of these buckling modes is predominantly carried out by using methods such as the generalized beam theory, the constrained finite strip method, and the finite element method, each of which relied on distinct computational tools. Consequently, each method has its own advantages and applicability depending on the specific context of the analysis. In recent years, innovative experimental techniques have been employed to investigate the buckling performance of stainless steel members with lipped C-section. Furthermore, extensive numerical simulations have been conducted to identify key factors influencing the buckling modes and ultimate bearing capacity of these components, leading to an optimization analysis of the section geometry. With the increasing adoption of the direct strength method, rapid calculation approaches for determining the bearing capacity of stainless steel members with lipped C-section under different buckling modes have been developed, providing a more efficient means of structural evaluation and design.This paper presented an in-depth exploration of the manufacturing processes and engineering applications of stainless steel members with lipped C-section. A comprehensive review was provided on the research contributions of both domestic and international scholars concerning the buckling performance of these components. The review encompassed various aspects, including methodologies for identifying buckling modes, descriptions of experimental setups, and design approaches.
Stainless steel, renowned for its excellent aesthetic properties and exceptional corrosion resistance, has found widespread application in structural components such as roofing systems, roof coverings, and curtain walls within architectural engineering. Stainless steel members with C-section have gained prominence due to their high material efficiency and favorable mechanical characteristics. The geometric configuration of these sections enhances the moment of inertia and torsional rigidity of the structural member, while simultaneously minimizing material usage, thereby fulfilling the dual objectives of structural safety and economic viability. However, the complex buckling behaviors and failure mechanisms associated with these sections present significant challenges in their design and analysis. Consequently, the buckling performance of stainless steel members with lipped C-section remains a focal point of ongoing research, with considerable emphasis on understanding and mitigating the associated risks.Up to the present, scholars have categorized the buckling performance of stainless steel members with lipped C-section based on failure modes into two primary types: single-mode buckling (global buckling, local buckling, and distortional buckling) and multi-mode coupled buckling (global-local buckling, global-distortional buckling, local-distortional buckling, and global-local-distortional buckling). The identification of these buckling modes is predominantly carried out by using methods such as the generalized beam theory, the constrained finite strip method, and the finite element method, each of which relied on distinct computational tools. Consequently, each method has its own advantages and applicability depending on the specific context of the analysis. In recent years, innovative experimental techniques have been employed to investigate the buckling performance of stainless steel members with lipped C-section. Furthermore, extensive numerical simulations have been conducted to identify key factors influencing the buckling modes and ultimate bearing capacity of these components, leading to an optimization analysis of the section geometry. With the increasing adoption of the direct strength method, rapid calculation approaches for determining the bearing capacity of stainless steel members with lipped C-section under different buckling modes have been developed, providing a more efficient means of structural evaluation and design.This paper presented an in-depth exploration of the manufacturing processes and engineering applications of stainless steel members with lipped C-section. A comprehensive review was provided on the research contributions of both domestic and international scholars concerning the buckling performance of these components. The review encompassed various aspects, including methodologies for identifying buckling modes, descriptions of experimental setups, and design approaches.
2025, 40(2): 10-20.
doi: 10.13206/j.gjgS24092004
Abstract:
In order to study the influence of corrugated steel plate shear wall in the semi-rigid frame on the seismic performance of the structure, a numerical model was established by ABAQUS to explore and analyze. Three different corrugated steel shear walls were designed and combined with the semi-rigid frame. First, a single-layer single-span finite element model was established and verified with the relevant research models in the existing literature to ensure the accuracy of the model. Then, on this basis, three corrugated steel plate shear walls with different structures were established, which were combined with the semi-rigid frame to form a semi-rigid frame-corrugated steel plate shear wall structure system. The seismic performance of the system under the action of lateral forces was studied, and finally the shear distribution law of the structural system of different walls embedded in the semi-rigid frame was explored. Finite element results showed that the semi-rigid frame (KKJ) had good ductility, less antilateral stiffness and low bearing capacity, its energy dissipation was relatively stable but the energy consumption was not strong; the semi-rigid frame filling wall (KKJ-Q1) could greatly increase the system stiffness, bearing capacity and energy consumption capacity, so as to reduce its ductility; the wall-filled foam concrete (KKJ-Q2) could inhibit the buckling of corrugated steel plates and improve the overall performance of the wall, its stiffness, bearing capacity and energy consumption capacity were further increased; the strengthening ends at both ends of the wall could avoid premature damage of the wall and loss of bearing capacity, its stiffness and bearing capacity had been improved to a certain extent, as the strengthening end height increased, to the plastic deformation of the wall shifted from both ends to the center, the wall failure mode was changed from bending to curved shear, the stiffness, bearing capacity and energy consumption capacity of the wall were further improved; as the external load increased, the wall shear force showed the trend of rising first and then decreasing, the shear ratio of wall Q3> Q2> Q1, the wall stiffness and shear ratio were proportional.
In order to study the influence of corrugated steel plate shear wall in the semi-rigid frame on the seismic performance of the structure, a numerical model was established by ABAQUS to explore and analyze. Three different corrugated steel shear walls were designed and combined with the semi-rigid frame. First, a single-layer single-span finite element model was established and verified with the relevant research models in the existing literature to ensure the accuracy of the model. Then, on this basis, three corrugated steel plate shear walls with different structures were established, which were combined with the semi-rigid frame to form a semi-rigid frame-corrugated steel plate shear wall structure system. The seismic performance of the system under the action of lateral forces was studied, and finally the shear distribution law of the structural system of different walls embedded in the semi-rigid frame was explored. Finite element results showed that the semi-rigid frame (KKJ) had good ductility, less antilateral stiffness and low bearing capacity, its energy dissipation was relatively stable but the energy consumption was not strong; the semi-rigid frame filling wall (KKJ-Q1) could greatly increase the system stiffness, bearing capacity and energy consumption capacity, so as to reduce its ductility; the wall-filled foam concrete (KKJ-Q2) could inhibit the buckling of corrugated steel plates and improve the overall performance of the wall, its stiffness, bearing capacity and energy consumption capacity were further increased; the strengthening ends at both ends of the wall could avoid premature damage of the wall and loss of bearing capacity, its stiffness and bearing capacity had been improved to a certain extent, as the strengthening end height increased, to the plastic deformation of the wall shifted from both ends to the center, the wall failure mode was changed from bending to curved shear, the stiffness, bearing capacity and energy consumption capacity of the wall were further improved; as the external load increased, the wall shear force showed the trend of rising first and then decreasing, the shear ratio of wall Q3> Q2> Q1, the wall stiffness and shear ratio were proportional.
2025, 40(2): 21-28.
doi: 10.13206/j.gjgS24091301
Abstract:
L-shaped, T-shaped and cross-shaped concrete-filled steel tubular columns are composed of square steel pipes and concrete, and the mechanical properties of the two materials were synthesized. A total of 9 specimens, including L-shaped, T-shaped and cross-shaped concrete-filled steel tubular columns with different length to slenderness ratios, were tested by axial compression tests, and the effects of the cross-section form and the length of the specimens on the damage morphology of the specimens, load-deflection curves, load-strain curves and load-Poisson’s ratio curves were investigated by comparative studies. The results showed that the short columns suffered from section strength damage and the long columns suffered from bending damage. Within the length range studied in this paper, the specimen length had a greater effect on the bearing capacity of L-section specimens and T-section specimens, and the bearing capacity of cross-section specimens was less affected by this effect. The horizontal deflections of all specimens were almost linearly related to the loads, and developed rapidly after yielding. Shaped columns showed the maximum strain at 1/2 height, and thePoisson’s ratio increased as loading proceeded.
L-shaped, T-shaped and cross-shaped concrete-filled steel tubular columns are composed of square steel pipes and concrete, and the mechanical properties of the two materials were synthesized. A total of 9 specimens, including L-shaped, T-shaped and cross-shaped concrete-filled steel tubular columns with different length to slenderness ratios, were tested by axial compression tests, and the effects of the cross-section form and the length of the specimens on the damage morphology of the specimens, load-deflection curves, load-strain curves and load-Poisson’s ratio curves were investigated by comparative studies. The results showed that the short columns suffered from section strength damage and the long columns suffered from bending damage. Within the length range studied in this paper, the specimen length had a greater effect on the bearing capacity of L-section specimens and T-section specimens, and the bearing capacity of cross-section specimens was less affected by this effect. The horizontal deflections of all specimens were almost linearly related to the loads, and developed rapidly after yielding. Shaped columns showed the maximum strain at 1/2 height, and thePoisson’s ratio increased as loading proceeded.
2025, 40(2): 29-36.
doi: 10.13206/j.gjgS24091402
Abstract:
Incorporating high-strength steel in circular tubed steel-reinforced concrete (STRC) stub columns offers several advantages, including avoiding local buckling in thin-walled steel and enhancing the mechanical properties of the columns. This paper employed the ABAQUS software to develop a finite element analysis model for circular steel tube-reinforced concrete stub columns under axial compression. Systematic parameter analysis was conducted to examine the effects of factors such as the shape and strength of the steel section, the strength of the steel tube and concrete, and the steel ratio. The load contribution values and section stresses of each component in the STRC columns were analyzed to further reveal the mechanism of the columns under axial compression. The results revealed that the bearing capacity of STRC columns under axial compression increased with the strength of the steel tube, steel profile, and concrete. The steel tube provided axial-bearing capacity through friction with the concrete, although this capacity was independent of the strength of the steel tube or the concrete. Additionally, the axial bearing capacity was affected by the steel tube indirectly through the confining effect on the concrete. The shape change of the steel profile would alter the confining area of the concrete, which in turn influenced the mechanical properties of the component under axial compression.Enhancing the strength of the steel profile would improve its load contribution, thereby affecting the bearing capacity of the component. With the same steel content, an increase in the strength of the steel tube had a greater effect on augmenting the axial bearing capacity than the same increase in the strength of the steel profile.
Incorporating high-strength steel in circular tubed steel-reinforced concrete (STRC) stub columns offers several advantages, including avoiding local buckling in thin-walled steel and enhancing the mechanical properties of the columns. This paper employed the ABAQUS software to develop a finite element analysis model for circular steel tube-reinforced concrete stub columns under axial compression. Systematic parameter analysis was conducted to examine the effects of factors such as the shape and strength of the steel section, the strength of the steel tube and concrete, and the steel ratio. The load contribution values and section stresses of each component in the STRC columns were analyzed to further reveal the mechanism of the columns under axial compression. The results revealed that the bearing capacity of STRC columns under axial compression increased with the strength of the steel tube, steel profile, and concrete. The steel tube provided axial-bearing capacity through friction with the concrete, although this capacity was independent of the strength of the steel tube or the concrete. Additionally, the axial bearing capacity was affected by the steel tube indirectly through the confining effect on the concrete. The shape change of the steel profile would alter the confining area of the concrete, which in turn influenced the mechanical properties of the component under axial compression.Enhancing the strength of the steel profile would improve its load contribution, thereby affecting the bearing capacity of the component. With the same steel content, an increase in the strength of the steel tube had a greater effect on augmenting the axial bearing capacity than the same increase in the strength of the steel profile.
Experimental Research on Pre-Tension and Bearing Capacity of a New Type of Removable One-Sided Bolts
2025, 40(2): 37-45.
doi: 10.13206/j.gjgS24091501
Abstract:
In order to assemble and disassemble steel members with closed-sections conveniently, a new type of detachable one-sided bolts was designed. This type of bolts mainly consists of a screw, a sleeve, a split spacer and a nut, and can be tightened in various ways. First of all, the pre-tension measurement and time-variation effect tests were conducted to study the pre-tension force. At the same time, the loss of pre-tension of the new bolt over time under different application sequences was also studied. And the applicable application methods were analyzed in the light of the actual situation. Then the load-displacement curves of bolted connections under shear and tensile loads were obtained by shear and tensile tests of single bolted connections. The force conditions and damage modes of single bolts under the two loads were analyzed, and the effects of different application sequences on the shear and tensile load capacities of bolted connections were investigated. Furthermore, the calculation method of tensile and shear bearing capacity of the new bolted connection was proposed based on the relevant codes and based on the test results. Finally, the bearing capacity of the new type of bolts was compared with that of different bolts in the relevant studies to assess the level of bearing capacity of the new type of bolts. The results showed that the maximum pre-tension relaxation of the bolts within 72 hours was 3.6%. It was recommended to use the screwing method where the sleeve was screwed first and then the screw (PB type), and the proportion of the torque applied first to the sleeve was more than 50%, which ensured that more than 60% of the pre-tensioning force was achieved. The method of application only affects the shear and tensile bearing capacity of the bolts in the case of friction-type connections, not in the case of compression-type connections. Split spacers played a controlling role in the forces on the bolted connection, the number of breaks in the split spacer under ultimate loads determined the damage mode in the shear model of the unilateral bolted connection, and the tensile bearing capacity depended on the shear cross-sectional area of the bolted split spacer. The shear and tensile ultimate bearing capacity obtained from the test matched well with the theoretical values obtained through the proposed bearing capacity calculation method, and the maximum error was within 11%, which proved that the bearing capacity calculation method possessed high accuracy. Compared with the same grade of one-sided bolts, the ultimate shear bearing capacity of frictional connection was similar, the ultimate shear bearing capacity of compressive connection was obviously superior, and the ultimate tensile bearing capacity of compressive connection was slightly lower.
In order to assemble and disassemble steel members with closed-sections conveniently, a new type of detachable one-sided bolts was designed. This type of bolts mainly consists of a screw, a sleeve, a split spacer and a nut, and can be tightened in various ways. First of all, the pre-tension measurement and time-variation effect tests were conducted to study the pre-tension force. At the same time, the loss of pre-tension of the new bolt over time under different application sequences was also studied. And the applicable application methods were analyzed in the light of the actual situation. Then the load-displacement curves of bolted connections under shear and tensile loads were obtained by shear and tensile tests of single bolted connections. The force conditions and damage modes of single bolts under the two loads were analyzed, and the effects of different application sequences on the shear and tensile load capacities of bolted connections were investigated. Furthermore, the calculation method of tensile and shear bearing capacity of the new bolted connection was proposed based on the relevant codes and based on the test results. Finally, the bearing capacity of the new type of bolts was compared with that of different bolts in the relevant studies to assess the level of bearing capacity of the new type of bolts. The results showed that the maximum pre-tension relaxation of the bolts within 72 hours was 3.6%. It was recommended to use the screwing method where the sleeve was screwed first and then the screw (PB type), and the proportion of the torque applied first to the sleeve was more than 50%, which ensured that more than 60% of the pre-tensioning force was achieved. The method of application only affects the shear and tensile bearing capacity of the bolts in the case of friction-type connections, not in the case of compression-type connections. Split spacers played a controlling role in the forces on the bolted connection, the number of breaks in the split spacer under ultimate loads determined the damage mode in the shear model of the unilateral bolted connection, and the tensile bearing capacity depended on the shear cross-sectional area of the bolted split spacer. The shear and tensile ultimate bearing capacity obtained from the test matched well with the theoretical values obtained through the proposed bearing capacity calculation method, and the maximum error was within 11%, which proved that the bearing capacity calculation method possessed high accuracy. Compared with the same grade of one-sided bolts, the ultimate shear bearing capacity of frictional connection was similar, the ultimate shear bearing capacity of compressive connection was obviously superior, and the ultimate tensile bearing capacity of compressive connection was slightly lower.
Numerical Analysis on Mechanical Properties of Bolted Beam-SHS Column Joints Strengthened by H-Steel
2025, 40(2): 46-55.
doi: 10.13206/j.gjgS23111501
Abstract:
T-head Square-neck One-side Bolt (TSOB) is a novel fastener, which can be used for the connection of Square Hollow Steel (SHS) members, with its simple construction, easy installation, no additional aids, can adapt to the rough installation manners in construction site, and has a large application potential. However, the current research on the performance of TSOBs bolted connections is mostly for model tests, the parameters of the research is single, lack of sufficient data support. In this paper, a three-dimensional nonlinear Finite Element (FE) model of TSOBs bolted beam-column joint was established by the ABAQUS FE analysis software, and the structural performance was further evaluated. The results of FE analysis were used to reveal the key structural response mechanism of this type of connections, and the effects of parameters such as the installation gap between the strengthening component and the Steel Hollow Section (SHS) column, the cross-section of the strengthening component, and the splicing position of the connection on the joints structural performance were investigated. The results showed that the three-dimensional FE model of TSOBs bolted beam-column joints established in this paper could accurately predict the failure mode of the joint under monotonous loading, the stress state of the components and the yielding sequence, obtaining the rotation-moment curve with high agreement with the experimental results, which was highly accurate and reliable, and provided a reliable way to analyze the working mechanism, parametric research and structural performance assessment. The load transfer path of the H-steel component in the SHS column was clear and simple, the material properties were fully utilized, and the working efficiency of the H-steel component was high, which was an ideal section for strengthening components. It was recommended that the installation clearance between the strengthening component and the SHS column should not exceed 2.0 mm. The load transfer path of cross-section component in planar joints was the same as that of the H-steel component, which should be designed separately in space joints according to the H-steel component in two directions and could not transfer the load between adjacent walls of the SHS column. The novel component formed by external welding of the short SHS in the middle section of the H-steel component could reduce the visual dislocation of the SHS columns without affecting the mechanical properties of the joints, and improve the hoisting efficiency of on-site lifting equipment and the installation efficiency of joints. In the strengthened joints, the splice of the SHS columns should be preferentially designed at the beam flanges.
T-head Square-neck One-side Bolt (TSOB) is a novel fastener, which can be used for the connection of Square Hollow Steel (SHS) members, with its simple construction, easy installation, no additional aids, can adapt to the rough installation manners in construction site, and has a large application potential. However, the current research on the performance of TSOBs bolted connections is mostly for model tests, the parameters of the research is single, lack of sufficient data support. In this paper, a three-dimensional nonlinear Finite Element (FE) model of TSOBs bolted beam-column joint was established by the ABAQUS FE analysis software, and the structural performance was further evaluated. The results of FE analysis were used to reveal the key structural response mechanism of this type of connections, and the effects of parameters such as the installation gap between the strengthening component and the Steel Hollow Section (SHS) column, the cross-section of the strengthening component, and the splicing position of the connection on the joints structural performance were investigated. The results showed that the three-dimensional FE model of TSOBs bolted beam-column joints established in this paper could accurately predict the failure mode of the joint under monotonous loading, the stress state of the components and the yielding sequence, obtaining the rotation-moment curve with high agreement with the experimental results, which was highly accurate and reliable, and provided a reliable way to analyze the working mechanism, parametric research and structural performance assessment. The load transfer path of the H-steel component in the SHS column was clear and simple, the material properties were fully utilized, and the working efficiency of the H-steel component was high, which was an ideal section for strengthening components. It was recommended that the installation clearance between the strengthening component and the SHS column should not exceed 2.0 mm. The load transfer path of cross-section component in planar joints was the same as that of the H-steel component, which should be designed separately in space joints according to the H-steel component in two directions and could not transfer the load between adjacent walls of the SHS column. The novel component formed by external welding of the short SHS in the middle section of the H-steel component could reduce the visual dislocation of the SHS columns without affecting the mechanical properties of the joints, and improve the hoisting efficiency of on-site lifting equipment and the installation efficiency of joints. In the strengthened joints, the splice of the SHS columns should be preferentially designed at the beam flanges.
2025, 40(2): 56-62.
doi: 10.13206/j.gjgS24022901
Abstract:
The loosening and detachment of high-strength bolts in steel bridges have become a hot topic in the steel structure industry. The existing manual inspection methods are laborious, time-consuming, and inefficient. Machine vision is used for detecting loose high-strength bolts in steel bridges, which can greatly improve detection efficiency, reduce detection costs, and ensure detection accuracy. However, this method still needs improvement in terms of bolt recognition and detection reliability, and has not yet been applied in engineering practice. To meet the demand for detecting the loosening angle of high-strength bolts in steel bridges, a high-strength bolt loosening detection algorithm based on the Hourglass network and digital image processing has been proposed. The algorithm consists of two parts: feature point recognition and angle calculation. The recognition algorithm consists of two parts: the key point localization network and the key point coordinate generation module. The key point localization network is a ResNet-50 feature extraction network designed to generate heatmaps containing the key points of the bolts. The key point coordinate generation module, based on the heatmaps, uses the localization network to detect the coordinates of the key points. The loosening angle algorithm works as follows: after obtaining the key point heatmaps, the bolt key points are transformed into an envelope diagram using the K-Means clustering algorithm. Once the bolt envelope diagram is obtained, the six corner points are numbered sequentially in a counterclockwise manner. The angle between corner point 1 and the positive x-axis is taken as the current angle of the bolt. By comparing the current angles at different times, the loosening angle of the bolt can be determined. Multiple photos of high-strength bolt connections on highway steel bridges have been collected, with the outer six corner points and center point of the nuts labeled. The bolt dataset has been expanded by applying geometric transformations, color transformations, adding Coarse Dropout noise, color perturbations, and other operations. A model training was conducted using the TensorFlow deep learning framework, and the recognition performance of the model at different distances was tested. The recognition results of the network in this paper were compared with CPMs and Two-Stage networks. The tests showed that the network model in this paper had excellent recognition performance, high computational efficiency, and good robustness. The APCK and AACC were as high as 97.6% and 99.5%, respectively. The APCK, AACC, and detection speed were superior to CPMs and Two-Stage networks.
The loosening and detachment of high-strength bolts in steel bridges have become a hot topic in the steel structure industry. The existing manual inspection methods are laborious, time-consuming, and inefficient. Machine vision is used for detecting loose high-strength bolts in steel bridges, which can greatly improve detection efficiency, reduce detection costs, and ensure detection accuracy. However, this method still needs improvement in terms of bolt recognition and detection reliability, and has not yet been applied in engineering practice. To meet the demand for detecting the loosening angle of high-strength bolts in steel bridges, a high-strength bolt loosening detection algorithm based on the Hourglass network and digital image processing has been proposed. The algorithm consists of two parts: feature point recognition and angle calculation. The recognition algorithm consists of two parts: the key point localization network and the key point coordinate generation module. The key point localization network is a ResNet-50 feature extraction network designed to generate heatmaps containing the key points of the bolts. The key point coordinate generation module, based on the heatmaps, uses the localization network to detect the coordinates of the key points. The loosening angle algorithm works as follows: after obtaining the key point heatmaps, the bolt key points are transformed into an envelope diagram using the K-Means clustering algorithm. Once the bolt envelope diagram is obtained, the six corner points are numbered sequentially in a counterclockwise manner. The angle between corner point 1 and the positive x-axis is taken as the current angle of the bolt. By comparing the current angles at different times, the loosening angle of the bolt can be determined. Multiple photos of high-strength bolt connections on highway steel bridges have been collected, with the outer six corner points and center point of the nuts labeled. The bolt dataset has been expanded by applying geometric transformations, color transformations, adding Coarse Dropout noise, color perturbations, and other operations. A model training was conducted using the TensorFlow deep learning framework, and the recognition performance of the model at different distances was tested. The recognition results of the network in this paper were compared with CPMs and Two-Stage networks. The tests showed that the network model in this paper had excellent recognition performance, high computational efficiency, and good robustness. The APCK and AACC were as high as 97.6% and 99.5%, respectively. The APCK, AACC, and detection speed were superior to CPMs and Two-Stage networks.
2025, 40(2): 63-70.
doi: 10.13206/j.gjgS24032101
Abstract:
Orthotropic steel bridge decks have become the predominant structural form for long-span bridges. However, the prevalence of welds in steel bridge decks leads to frequent instances of fatigue cracking at the weld joints due to the high occurrence of welding defects such as initial cracks, inclusions, and porosity on the inner or outer surfaces of the welds. Current research often simplifies welding defects as planar semi-elliptical shapes, overlooking their physical properties, which results in unclear understanding of how these defects affect the mechanism of fatigue crack propagation. To investigate the influence of welding defects on fatigue crack propagation behaviors in steel bridge decks, a numerical simulation was conducted. This study integrated linear elastic fracture mechanics and the FRANC3D-ABAQUS interactive simulation technique. A refined finite element model of a semi-U rib with cracks and inclusions was established using ABAQUS. Inclusions were inserted at the weld toe, and subsequently, this finite element model incorporating inclusions was imported into FRANC3D. An initial fatigue crack was introduced near the inclusion, and variations in the elastic modulus of the inclusion were employed to simulate the effects of soft and hard inclusions. The interaction between fatigue cracks and inclusions at the weld joints of U ribs and deck plates was analyzed. This analysis revealed the impact of welding inclusions on crucial parameters such as stress intensity factors (SIF), crack morphology, and propagation rate. The simulation accurately depicted the dynamic trajectory of crack propagation through inclusions. The results indicated that welding inclusions alter the stress field of fatigue cracks, with stress concentration points located internally within hard inclusions and near the crack tip in the presence of soft inclusions, resulting in I-III type cracks at the weld toe influenced by inclusion defects. The elastic modulus of inclusions was found to significantly influence the characteristics of fatigue crack propagation. Soft inclusions briefly inhibited the stress intensity factor at the crack tip but ultimately accelerated crack propagation rates throughout the crack’s lifecycle, resulting in a 7.8% reduction in fatigue life compared to welds without inclusions. Conversely, hard inclusions extended weld fatigue life by 10.1%. Crack morphology tended to flatten during propagation, influenced by the presence of inclusions and their impact on symmetry. Soft inclusions attracted crack propagation near the inclusion, causing localized concentrated expansion, while hard inclusions induced a deviation in crack propagation direction due to repulsion effects. The effect of hard inclusions on crack shape was particularly pronounced, with a 22% increase in flatness observed at the crack tip near the hard inclusion. Strict control over the distribution and type of inclusions during the welding process of steel bridge decks was recommended. Inclusion effects should be carefully considered when predicting fatigue life in welds.
Orthotropic steel bridge decks have become the predominant structural form for long-span bridges. However, the prevalence of welds in steel bridge decks leads to frequent instances of fatigue cracking at the weld joints due to the high occurrence of welding defects such as initial cracks, inclusions, and porosity on the inner or outer surfaces of the welds. Current research often simplifies welding defects as planar semi-elliptical shapes, overlooking their physical properties, which results in unclear understanding of how these defects affect the mechanism of fatigue crack propagation. To investigate the influence of welding defects on fatigue crack propagation behaviors in steel bridge decks, a numerical simulation was conducted. This study integrated linear elastic fracture mechanics and the FRANC3D-ABAQUS interactive simulation technique. A refined finite element model of a semi-U rib with cracks and inclusions was established using ABAQUS. Inclusions were inserted at the weld toe, and subsequently, this finite element model incorporating inclusions was imported into FRANC3D. An initial fatigue crack was introduced near the inclusion, and variations in the elastic modulus of the inclusion were employed to simulate the effects of soft and hard inclusions. The interaction between fatigue cracks and inclusions at the weld joints of U ribs and deck plates was analyzed. This analysis revealed the impact of welding inclusions on crucial parameters such as stress intensity factors (SIF), crack morphology, and propagation rate. The simulation accurately depicted the dynamic trajectory of crack propagation through inclusions. The results indicated that welding inclusions alter the stress field of fatigue cracks, with stress concentration points located internally within hard inclusions and near the crack tip in the presence of soft inclusions, resulting in I-III type cracks at the weld toe influenced by inclusion defects. The elastic modulus of inclusions was found to significantly influence the characteristics of fatigue crack propagation. Soft inclusions briefly inhibited the stress intensity factor at the crack tip but ultimately accelerated crack propagation rates throughout the crack’s lifecycle, resulting in a 7.8% reduction in fatigue life compared to welds without inclusions. Conversely, hard inclusions extended weld fatigue life by 10.1%. Crack morphology tended to flatten during propagation, influenced by the presence of inclusions and their impact on symmetry. Soft inclusions attracted crack propagation near the inclusion, causing localized concentrated expansion, while hard inclusions induced a deviation in crack propagation direction due to repulsion effects. The effect of hard inclusions on crack shape was particularly pronounced, with a 22% increase in flatness observed at the crack tip near the hard inclusion. Strict control over the distribution and type of inclusions during the welding process of steel bridge decks was recommended. Inclusion effects should be carefully considered when predicting fatigue life in welds.
2025, 40(2): 71-75.
doi: 10.13206/j.gjgS24050620
Abstract:
The origin and application of structural performance factors were briefly introduced. Research results on the structural performance factors in single-degree-of-freedon (SDOF) systems was presented, related applications in seismic design codes of Europe, the United States, Australia, New Zealand, Mexico, Chile, and China’s Taiwan region were introduced, they all use smaller performance factor for short periods. Based on research results of past two decades, formulas consistent with the response spectra in current seismic codes of China were proposed to improve the practice of Chinese seismic design. Compared with various international seismic codes, the new proposal was suggested to extend the range of application of the equal displacement law to the equal displacement stage of the elastic response spectrum, therefore it would be the most conservative.
The origin and application of structural performance factors were briefly introduced. Research results on the structural performance factors in single-degree-of-freedon (SDOF) systems was presented, related applications in seismic design codes of Europe, the United States, Australia, New Zealand, Mexico, Chile, and China’s Taiwan region were introduced, they all use smaller performance factor for short periods. Based on research results of past two decades, formulas consistent with the response spectra in current seismic codes of China were proposed to improve the practice of Chinese seismic design. Compared with various international seismic codes, the new proposal was suggested to extend the range of application of the equal displacement law to the equal displacement stage of the elastic response spectrum, therefore it would be the most conservative.
