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Steel Construction Published the List of Highly Influential Articles of 2020
2023 Vol. 38, No. 1
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2023, 38(1): 1-12.
doi: 10.13206/j.gjgS22110101
Abstract
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Abstract:
To study seismic performance of embedded and reinforced connection with cantilever beam, and the effect of change of component parameters on the seismic performance of connection. quasi-static analysis on the embedded and reinforced connection with cantilever beam was carried out, the calculation results can provide an optimized scheme for designing of this type of connection. By changing the number of bolts, the thickness and width of the extended flange, the length of the cantilever beam respectively, a series of finite element numerical calculation models of connections were set up. Failure mode, hysteretic behaviour, energy dissipation capacity, bearing capacity, stiffness degradation, and stress path are calculated and analyzed. Numerical calculation results of each series of connection are compared to analyze the effect of the number of bolts, the thickness and width of the extended flange, the length of the cantilever beam on mechanical properties of the connection. The analysis results show that the number of flange bolts has little effect on mechanical properties of the connection. Increasing the number of flange bolts on the basis of the connection designed by the equal strength design method has no obvious effect on the mechanical properties of the connection, while decreasing the number of flange bolts will reduce the integrity of the connection, and the connection will buckle in advance, but the bearing capacity and stiffness of the connection will not decrease significantly. Increasing the thickness of the extended flange and the width of the cantilever flange can significantly improve the energy dissipation capacity, bearing capacity and stiffness of the connection. However, when the thickness and width of the extended flange reach a certain degree, the energy dissipation capacity is not significantly improved, and the bearing capacity degrades rapidly. The stiffness degradation of the connection in the elastoplasticity stage is accelerated, and the failure of connection failure mode also changes, but the stress concentration is relieved. When the width of the extended flange is too wide, on the contrary, the energy consumption capacity of nodes begins to decrease. The length of the cantilever beam segment has a certain effect on the mechanical properties of the connection. Increasing the length of the cantilever beam can improve the hysteretic performance, bearing capacity and stiffness of the connection. On the whole, the effect on improvement is less obvious than that of changing the width and thickness of the extended flange. Because the thickness and width of the flange of the cantilever beam have a great effect on mechanical properties of the connection, it is recommended that the selection of the thickness and width of the extended flange are controlled by the section when the connection is designed, and the ratio of the cross-sectional area of the extended beam to the cross-sectional area of the flange of the middle beam section is recommended to be within the range of 1.10~1.29. Properly increasing the section of the extended flange of the cantilever beam can significantly improve the energy dissipation capacity, bearing capacity and stiffness of the connection. However, when the section of the extended flange of the cantilever beam is too large, the failure mode will change, and the mechanical properties will be slightly improved, but the degradation rate of the bearing capacity and stiffness of the connection will be accelerated.
To study seismic performance of embedded and reinforced connection with cantilever beam, and the effect of change of component parameters on the seismic performance of connection. quasi-static analysis on the embedded and reinforced connection with cantilever beam was carried out, the calculation results can provide an optimized scheme for designing of this type of connection. By changing the number of bolts, the thickness and width of the extended flange, the length of the cantilever beam respectively, a series of finite element numerical calculation models of connections were set up. Failure mode, hysteretic behaviour, energy dissipation capacity, bearing capacity, stiffness degradation, and stress path are calculated and analyzed. Numerical calculation results of each series of connection are compared to analyze the effect of the number of bolts, the thickness and width of the extended flange, the length of the cantilever beam on mechanical properties of the connection. The analysis results show that the number of flange bolts has little effect on mechanical properties of the connection. Increasing the number of flange bolts on the basis of the connection designed by the equal strength design method has no obvious effect on the mechanical properties of the connection, while decreasing the number of flange bolts will reduce the integrity of the connection, and the connection will buckle in advance, but the bearing capacity and stiffness of the connection will not decrease significantly. Increasing the thickness of the extended flange and the width of the cantilever flange can significantly improve the energy dissipation capacity, bearing capacity and stiffness of the connection. However, when the thickness and width of the extended flange reach a certain degree, the energy dissipation capacity is not significantly improved, and the bearing capacity degrades rapidly. The stiffness degradation of the connection in the elastoplasticity stage is accelerated, and the failure of connection failure mode also changes, but the stress concentration is relieved. When the width of the extended flange is too wide, on the contrary, the energy consumption capacity of nodes begins to decrease. The length of the cantilever beam segment has a certain effect on the mechanical properties of the connection. Increasing the length of the cantilever beam can improve the hysteretic performance, bearing capacity and stiffness of the connection. On the whole, the effect on improvement is less obvious than that of changing the width and thickness of the extended flange. Because the thickness and width of the flange of the cantilever beam have a great effect on mechanical properties of the connection, it is recommended that the selection of the thickness and width of the extended flange are controlled by the section when the connection is designed, and the ratio of the cross-sectional area of the extended beam to the cross-sectional area of the flange of the middle beam section is recommended to be within the range of 1.10~1.29. Properly increasing the section of the extended flange of the cantilever beam can significantly improve the energy dissipation capacity, bearing capacity and stiffness of the connection. However, when the section of the extended flange of the cantilever beam is too large, the failure mode will change, and the mechanical properties will be slightly improved, but the degradation rate of the bearing capacity and stiffness of the connection will be accelerated.
2023, 38(1): 13-20.
doi: 10.13206/j.gjgS19102601
Abstract:
At present, most of the bridge projects in China are still simply supported beam bridges. Under the action of transverse load, the simply supported beam bridge is mainly flexural. As a kind of steel structure girder used earlier, honeycomb beam has the characteristics of strong bending resistance, but it is rarely used in simply supported beam bridge. This is mainly due to the large web height of honeycomb beam, which is prone to web buckling distortion under dynamic loads such as vehicle loads. In order to apply the honeycomb beam to the field of bridge engineering, based on the appearance of honeycomb beam, a new type of steel structure main beam-steel octagon-web beam was proposed. The web stress calculation method and pure shear buckling calculation coefficient of the structure were studied in order to provide reference for the practical application of the structure.Based on the assumption of the Vierendeel truss theory, the web of the structure is divided into five calculation areas, the web stress calculation method is proposed and the corresponding calculation formula is obtained, and the rationality of the web stress calculation method is verified by comparing with the test results. In order to study the pure shear buckling coefficient of the web, based on the pure shear rectangular thin plate buckling calculation theory, the general finite element software ABAQUS is used to calculate the buckling coefficient for 480 octagonal thin plate with different design parameters and different boundary conditions. By modifying the calculation formula of the pure shear rectangular thin plate buckling coefficient with different boundary conditions, the buckling coefficient of the regular octagonal perforated web under the pure shear stress is obtained. The results show that under the transverse load, the bottom slab and top slab of the structure are mainly subject to axial force, and the shear force effect can be ignored, while the web is mainly subject to shear force, and the axial force effect can be ignored. Through the static load bending test of the specimen, the bending failure mode of the structure is obtained, and the web buckling phenomenon occurs at the loading point of the test piece. The measured values of the strain at the edge of the web opening are converted into the actual values of the stress, and compared with the calculated values of the web stress. It can be found that the proposed web stress calculation method can better predict the distribution mode of circumferential stress of circular holes, and the circumferential stress distribution is approximately uniform. In the calculating section θ=π/2, there is a large difference between the theoretical calculation and the measured values due to the calculation error caused by the assumption that the center of the circular hole is the inflection point in the simplified calculation. Based on the finite element software ABAQUS and data fitting, the buckling coefficient of octagonal circular perforated plate is proposed, which can provide a reference for the relevant design of the structure.
At present, most of the bridge projects in China are still simply supported beam bridges. Under the action of transverse load, the simply supported beam bridge is mainly flexural. As a kind of steel structure girder used earlier, honeycomb beam has the characteristics of strong bending resistance, but it is rarely used in simply supported beam bridge. This is mainly due to the large web height of honeycomb beam, which is prone to web buckling distortion under dynamic loads such as vehicle loads. In order to apply the honeycomb beam to the field of bridge engineering, based on the appearance of honeycomb beam, a new type of steel structure main beam-steel octagon-web beam was proposed. The web stress calculation method and pure shear buckling calculation coefficient of the structure were studied in order to provide reference for the practical application of the structure.Based on the assumption of the Vierendeel truss theory, the web of the structure is divided into five calculation areas, the web stress calculation method is proposed and the corresponding calculation formula is obtained, and the rationality of the web stress calculation method is verified by comparing with the test results. In order to study the pure shear buckling coefficient of the web, based on the pure shear rectangular thin plate buckling calculation theory, the general finite element software ABAQUS is used to calculate the buckling coefficient for 480 octagonal thin plate with different design parameters and different boundary conditions. By modifying the calculation formula of the pure shear rectangular thin plate buckling coefficient with different boundary conditions, the buckling coefficient of the regular octagonal perforated web under the pure shear stress is obtained. The results show that under the transverse load, the bottom slab and top slab of the structure are mainly subject to axial force, and the shear force effect can be ignored, while the web is mainly subject to shear force, and the axial force effect can be ignored. Through the static load bending test of the specimen, the bending failure mode of the structure is obtained, and the web buckling phenomenon occurs at the loading point of the test piece. The measured values of the strain at the edge of the web opening are converted into the actual values of the stress, and compared with the calculated values of the web stress. It can be found that the proposed web stress calculation method can better predict the distribution mode of circumferential stress of circular holes, and the circumferential stress distribution is approximately uniform. In the calculating section θ=π/2, there is a large difference between the theoretical calculation and the measured values due to the calculation error caused by the assumption that the center of the circular hole is the inflection point in the simplified calculation. Based on the finite element software ABAQUS and data fitting, the buckling coefficient of octagonal circular perforated plate is proposed, which can provide a reference for the relevant design of the structure.
2023, 38(1): 21-28.
doi: 10.13206/j.gjgS22042702
Abstract:
A new type of cold-formed thin-walled steel wall stud called phosphogypsum-filled thin-walled square steel tube(PFST) stud was proposed in this paper. The stud consists of a square steel tube and phosphogypsum inside, which meets the characteristics of lightweight. In this kind of stud, the supporting effect of the core phosphogypsum can delay the local buckling of the thin-walled square steel tube, and the restraint effect of the thin-walled square steel tube can improve the strength of the core phosphogypsum. Hence, the mechanical properties of the two materials can be fully developed and the axial bearing capacity of the stud can be effectively improved. To study the axial compression performance of PFST studs, 3 hollow steel tubes(HST) and 24 PFST studs were designed and fabricated with consideration of the section with or without phosphogypsum, water-solid ratio, hollow ratio and wall thickness of steel tube. Through axial loading tests, the failure mode, load-deformation curve, load-strain curve, and bearing capacity were analyzed. The test results indicated that the hollow steel tube stud presented a failure mode of local buckling. For the studs filled with phosphogypsum, the “drum shape” failure mode was observed. It is evidenced that the phosphogypsum can delay the local buckling of the steel tube, and change the failure mode of the stud. Compared with the hollow studs, the axial bearing capacity of the studs filled with phosphogypsum increased by 65.52%. The hollowness ratio has a significant impact on the bearing capacity of the stud, due to the fact that the water content of phosphogypsum varies with the hollowness ratio, which finally affects the strength of the infill material. The axial bearing capacity of the stud improved with decrease of water-solid ratio of phosphogypsum. When the water-solid ratio decreased from 0.9 to 0.8 and 0.7, the bearing capacity increased by 6.36% and 12.42%, respectively. Increasing the thickness of the steel tube can significantly improve the axial compression performance of the stud. When the thickness increased from 0.85 mm to 1.48 mm and 1.93 mm, the axial bearing capacity of the stud increased by 115.36% and 176.55%, respectively. Based on the superposition theory, the axial bearing capacity calculations of the HST and PFST studs were deduced. The results showed that the calculated formula has good accuracy, which can accurately predict the axial bearing capacity of the stud. In conclusion, the PFST stud has good mechanical properties and broad, wide application prospects. This kind of stud can also provide a feasible path for applying phosphogypsum.
A new type of cold-formed thin-walled steel wall stud called phosphogypsum-filled thin-walled square steel tube(PFST) stud was proposed in this paper. The stud consists of a square steel tube and phosphogypsum inside, which meets the characteristics of lightweight. In this kind of stud, the supporting effect of the core phosphogypsum can delay the local buckling of the thin-walled square steel tube, and the restraint effect of the thin-walled square steel tube can improve the strength of the core phosphogypsum. Hence, the mechanical properties of the two materials can be fully developed and the axial bearing capacity of the stud can be effectively improved. To study the axial compression performance of PFST studs, 3 hollow steel tubes(HST) and 24 PFST studs were designed and fabricated with consideration of the section with or without phosphogypsum, water-solid ratio, hollow ratio and wall thickness of steel tube. Through axial loading tests, the failure mode, load-deformation curve, load-strain curve, and bearing capacity were analyzed. The test results indicated that the hollow steel tube stud presented a failure mode of local buckling. For the studs filled with phosphogypsum, the “drum shape” failure mode was observed. It is evidenced that the phosphogypsum can delay the local buckling of the steel tube, and change the failure mode of the stud. Compared with the hollow studs, the axial bearing capacity of the studs filled with phosphogypsum increased by 65.52%. The hollowness ratio has a significant impact on the bearing capacity of the stud, due to the fact that the water content of phosphogypsum varies with the hollowness ratio, which finally affects the strength of the infill material. The axial bearing capacity of the stud improved with decrease of water-solid ratio of phosphogypsum. When the water-solid ratio decreased from 0.9 to 0.8 and 0.7, the bearing capacity increased by 6.36% and 12.42%, respectively. Increasing the thickness of the steel tube can significantly improve the axial compression performance of the stud. When the thickness increased from 0.85 mm to 1.48 mm and 1.93 mm, the axial bearing capacity of the stud increased by 115.36% and 176.55%, respectively. Based on the superposition theory, the axial bearing capacity calculations of the HST and PFST studs were deduced. The results showed that the calculated formula has good accuracy, which can accurately predict the axial bearing capacity of the stud. In conclusion, the PFST stud has good mechanical properties and broad, wide application prospects. This kind of stud can also provide a feasible path for applying phosphogypsum.
2023, 38(1): 29-36.
doi: 10.13206/j.gjgS22072002
Abstract:
The transmission tower is a kind of wind-sensitive structure with the characteristics of high self-weight, structural flexibility and small damping, and is sensitive to wind load excitation. The wind load in the typhoon-prone areas in the southeast coast is an important cause of tower collapse and accidents. In order to improve the safety and reliability of transmission lines in the southeast coastal areas of China, it is particularly important to reasonably evaluate the wind resistance performance of transmission towers in this area. In this paper, the dynamic characteristics analysis, wind-induced vibration response analysis and wind-resistant performance evaluation of a typical transmission tower are carried out based on a new 220 kV double-circuit transmission line in the coastal area of Fuding, Fujian Province. Firstly, the dynamic characteristics of the transmission tower were tested on site to test the response of the transmission tower under natural excitation, and the dynamic characteristics parameters such as the frequency and damping ratio of the transmission tower are identified by the random subspace method; Secondly, the finite element calculation model of the transmission tower is established by using ANSYS software. Through theoretical analysis and field measurement of the dynamic characteristics of the transmission tower, the vibration characteristics of the tower are further understood and mastered, and the correctness of the finite element model is verified; Further, according to the existing specifications, the static wind load analysis of 0°, 45°, 60° and 90° and the wind vibration response analysis with wind speed return period of 30 years, 50 years and 100 years are carried out for the transmission tower, and the maximum compressive stress value of the main material of the transmission tower under the static and fluctuating wind load is obtained. On this basis, the wind resistance performance of the transmission tower is evaluated by the tower top offset ratio, the pole bending ratio and other evaluation parameters. The results show that this method can effectively evaluate the wind resistance of the transmission tower with the wind speed return period of 30 years, 50 years and 100 years, and the conclusion that the wind resistance design of the transmission tower is relatively safe is obtained. The research and related conclusions have important reference value for the wind resistance design and wind resistance performance evaluation of transmission towers in the future.
The transmission tower is a kind of wind-sensitive structure with the characteristics of high self-weight, structural flexibility and small damping, and is sensitive to wind load excitation. The wind load in the typhoon-prone areas in the southeast coast is an important cause of tower collapse and accidents. In order to improve the safety and reliability of transmission lines in the southeast coastal areas of China, it is particularly important to reasonably evaluate the wind resistance performance of transmission towers in this area. In this paper, the dynamic characteristics analysis, wind-induced vibration response analysis and wind-resistant performance evaluation of a typical transmission tower are carried out based on a new 220 kV double-circuit transmission line in the coastal area of Fuding, Fujian Province. Firstly, the dynamic characteristics of the transmission tower were tested on site to test the response of the transmission tower under natural excitation, and the dynamic characteristics parameters such as the frequency and damping ratio of the transmission tower are identified by the random subspace method; Secondly, the finite element calculation model of the transmission tower is established by using ANSYS software. Through theoretical analysis and field measurement of the dynamic characteristics of the transmission tower, the vibration characteristics of the tower are further understood and mastered, and the correctness of the finite element model is verified; Further, according to the existing specifications, the static wind load analysis of 0°, 45°, 60° and 90° and the wind vibration response analysis with wind speed return period of 30 years, 50 years and 100 years are carried out for the transmission tower, and the maximum compressive stress value of the main material of the transmission tower under the static and fluctuating wind load is obtained. On this basis, the wind resistance performance of the transmission tower is evaluated by the tower top offset ratio, the pole bending ratio and other evaluation parameters. The results show that this method can effectively evaluate the wind resistance of the transmission tower with the wind speed return period of 30 years, 50 years and 100 years, and the conclusion that the wind resistance design of the transmission tower is relatively safe is obtained. The research and related conclusions have important reference value for the wind resistance design and wind resistance performance evaluation of transmission towers in the future.
2023, 38(1): 37-65.
doi: 10.13206/j.gjgS22121903
Abstract:
The current seismic design method in China based on Code for Seismic Design of Buildings(GB 50011-2010), referred to as the prescriptive design method, inadequately considers the variations in ductility among different structural systems, impeding the recognition of the superior anti-seismic ductility of steel structures. Moreover, with the challenges in promptly updating codes to align with the development and application of new materials and technologies, it is essential to develop performance-based seismic design(PBSD) methods. This paper provides a comprehensive comparative analysis of the PBSD methods outlined in domestic codes, as well as the issues associated with their implementation. Drawing on international advanced PBSD concepts and existing engineering experience, an improved PBSD method for steel structures is proposed. The proposed method comprehensively addresses the design process, establishment of performance objectives, analysis methods, and performance evaluation, offering a robust framework for the seismic design of steel structures. It presents an alternative to the traditional prescriptive design method and provides increased flexibility, allowing for its application to various high ductility structures and new structural systems. This method can be also extended to other types of structural analysis such as those involving, wind, fire, corrosion and comfort. To further enhance the performance design process of steel structures throughout their full life cycle, numerical simulation calculations are recommended as a fundamental tool for various performance designs. While the proposed method shows promise in enabling positive outcomes for steel structures and promoting their application and development.
The current seismic design method in China based on Code for Seismic Design of Buildings(GB 50011-2010), referred to as the prescriptive design method, inadequately considers the variations in ductility among different structural systems, impeding the recognition of the superior anti-seismic ductility of steel structures. Moreover, with the challenges in promptly updating codes to align with the development and application of new materials and technologies, it is essential to develop performance-based seismic design(PBSD) methods. This paper provides a comprehensive comparative analysis of the PBSD methods outlined in domestic codes, as well as the issues associated with their implementation. Drawing on international advanced PBSD concepts and existing engineering experience, an improved PBSD method for steel structures is proposed. The proposed method comprehensively addresses the design process, establishment of performance objectives, analysis methods, and performance evaluation, offering a robust framework for the seismic design of steel structures. It presents an alternative to the traditional prescriptive design method and provides increased flexibility, allowing for its application to various high ductility structures and new structural systems. This method can be also extended to other types of structural analysis such as those involving, wind, fire, corrosion and comfort. To further enhance the performance design process of steel structures throughout their full life cycle, numerical simulation calculations are recommended as a fundamental tool for various performance designs. While the proposed method shows promise in enabling positive outcomes for steel structures and promoting their application and development.
2023, 38(1): 66-68.
doi: 10.13206/j.gjgG22111209
Abstract:
Function of sagrods in parallel purlin system is studied. Due to the small thickness of the cold-formed purlin, its web deforms locally at the sagrod point, slacking occurs in the sagrod, leading to noneffective sagrod. The zigzag arrangement of sagrods in the adjacent bays weakens dramatically the tensile stiffness of the sagrods further. On the other hand, the stiffness demand on the sagrod increases parabolically with the number of the purlins. Combining these factors, it can be concluded that the sagrods in purlin system have negligible effect of the strength and buckling capacity of the purlins. Proposals are presented on the layout of sagrod systems and cold-formed C sections shall be used as sagrods.
Function of sagrods in parallel purlin system is studied. Due to the small thickness of the cold-formed purlin, its web deforms locally at the sagrod point, slacking occurs in the sagrod, leading to noneffective sagrod. The zigzag arrangement of sagrods in the adjacent bays weakens dramatically the tensile stiffness of the sagrods further. On the other hand, the stiffness demand on the sagrod increases parabolically with the number of the purlins. Combining these factors, it can be concluded that the sagrods in purlin system have negligible effect of the strength and buckling capacity of the purlins. Proposals are presented on the layout of sagrod systems and cold-formed C sections shall be used as sagrods.
