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Steel Construction Published the List of Highly Influential Articles of 2020
2020 Vol. 35, No. 5
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2020, 35(5): 1-9.
doi: 10.13206/j.gjgS20030902
Abstract
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Abstract:
Cold-formed thin-walled steel columns can be made into many sections, of which the U-section (also called channel section) and C-section are the most commonly used and studied. However, although the cold-formed thin-walled steel column has the advantages of light weight and short construction period, it is also prone to buckle, which is not conducive to structures. Previous studies have shown that the cold-formed thin-walled steel channel columns with complex edge stiffeners (also called G-section columns) have higher load-bearing capacities and critical distortional buckling stress. In this paper, the axial behavior of pin-ended G-section columns was studied by means of experiments and finite element analysis.
In order to study the influence of cross-sectional dimensions and column lengths on the failure modes and load-bearing capacities of G-section columns, a total of 18 cold-formed thin-walled steel G-section columns with nominal thickness of 2.0 mm were tested, and their failure modes, load-displacement curves, load-strain curves and ultimate capacities were analyzed. There were three kinds of cross-sectional dimensions (nominal web depth was 150 mm, 200 mm and 300 mm, respectively), and the slenderness ratios of specimens varied from 15 to 70. Before the tests, the actual dimensions of cross-section, material properties and initial geometric imperfections of the specimens were measured. In the test, it was observed that the specimens with nominal web depth of 150 mm failed in distortional buckling; for the specimens with nominal web depths of 200 mm and 300 mm, when the length of the specimen was less than or equal to 1000 mm, local buckling failure occurred, and the rest specimens failed in local-global interactive buckling, and the half-wave length of local buckling was approximately equal to the web depth.
Then, the finite element models were established in ABAQUS to simulate the specimens, and the models were validated based on the test results. The calibrated finite element model was subsequently adopted to investigate the influence of the flange width-to-thickness ratio, the web depth-to-thickness ratio and the dimension of complex edge stiffener on the ultimate capacities of the cold-formed thin-walled steel G-section columns. The results showed that the ultimate capacity of the G-section column increased with the increase of flange width-to-thickness ratio and the dimension of complex edge stiffener, and decreased with the increase of web depth-to-thickness ratio.
Cold-formed thin-walled steel columns can be made into many sections, of which the U-section (also called channel section) and C-section are the most commonly used and studied. However, although the cold-formed thin-walled steel column has the advantages of light weight and short construction period, it is also prone to buckle, which is not conducive to structures. Previous studies have shown that the cold-formed thin-walled steel channel columns with complex edge stiffeners (also called G-section columns) have higher load-bearing capacities and critical distortional buckling stress. In this paper, the axial behavior of pin-ended G-section columns was studied by means of experiments and finite element analysis.
In order to study the influence of cross-sectional dimensions and column lengths on the failure modes and load-bearing capacities of G-section columns, a total of 18 cold-formed thin-walled steel G-section columns with nominal thickness of 2.0 mm were tested, and their failure modes, load-displacement curves, load-strain curves and ultimate capacities were analyzed. There were three kinds of cross-sectional dimensions (nominal web depth was 150 mm, 200 mm and 300 mm, respectively), and the slenderness ratios of specimens varied from 15 to 70. Before the tests, the actual dimensions of cross-section, material properties and initial geometric imperfections of the specimens were measured. In the test, it was observed that the specimens with nominal web depth of 150 mm failed in distortional buckling; for the specimens with nominal web depths of 200 mm and 300 mm, when the length of the specimen was less than or equal to 1000 mm, local buckling failure occurred, and the rest specimens failed in local-global interactive buckling, and the half-wave length of local buckling was approximately equal to the web depth.
Then, the finite element models were established in ABAQUS to simulate the specimens, and the models were validated based on the test results. The calibrated finite element model was subsequently adopted to investigate the influence of the flange width-to-thickness ratio, the web depth-to-thickness ratio and the dimension of complex edge stiffener on the ultimate capacities of the cold-formed thin-walled steel G-section columns. The results showed that the ultimate capacity of the G-section column increased with the increase of flange width-to-thickness ratio and the dimension of complex edge stiffener, and decreased with the increase of web depth-to-thickness ratio.
2020, 35(5): 10-18.
doi: 10.13206/j.gjgS20022301
Abstract:
After the introduction of the standing seam metal roof system in China, the research on the force transmission principle and the mechanical performance has not been mature, which is not conducive to the popularization and application of such roofing systems. The problems involved in the upright lock-edge metal roofing system are comprehensive and complex, and require a lot of scientific research to solve them. Based on the above problems, this article targeted the relevant research on the crimping joint of the upright edge-sealing metal roof.
First, the structure of the metal roof is introduced. The wind resistance principle of the roof slab is obtained through the preliminary analysis of the structure of the aluminum magnesium manganese upright metal roofing system:the top roof slab is first deformed upward, and the rising force is transmitted to the occlusion structure. The bearing, the bearing then transmits the load from the self-tapping screw to the purlin, and finally distributes it to the main structure. The order of force transmission is wind-absorbing load→roof panel→fixed support→self-tapping screw→purlin→main structure.
Using non-linear finite element software midas FEA to simulate the whole process of the roof system under the wind load, the wind resistance performance of the vertical locking metal roof system was studied. Combined with the domestic research on the metal roofing system's resistance to wind damage, a uniform load of 2 kN/m2 and 5 kN/m2 is applied to the roof slab and vertical ribs, and the stress and stress of the roof slab under different loads are analyzed In the deformation situation, the Mises stress cloud maps at different nodes are obtained. Under the uniform load of 2 kN/m2, the local connection between the support and the metal hemming due to mutual extrusion and slip, the local stress is large, reaching 220 MPa. But at this time, the middle of the slab still stays at a relatively low stress level; under the uniform load of 5 kN/m2, the stress in the middle of the roof slab and the area near the support has reached the yield strength. Under the uniform load of 2 kN/m2, the maximum vertical deflection value of the mid-span position of the roof slab is about 48.18 mm, the deflection value is relatively large, and the opening at the support makes the deflection value of the two sides of the panel surface greater than that of the middle panel Its impact on the overall roofing system usage status. When the value of the uniformly distributed wind load applied to the roof panel is 5 kN/m2, the mid-span deflection is 220 mm. This is because the roof panel has detached from the support, causing the deflection to rapidly increase. At this time, the excessive deflection to normal use of the panel has an unrecoverable impact. By analyzing the deformation of the roof slab under load, it can be seen that the adjacent roof slabs are moved to the two sides by the curling straight ribs under the wind exposure, and the vertical locking part of the roof slab continuously rubs against the aluminum alloy support extrusion, with the continuous development of deformation, eventually detached from the support. Therefore, under the action of the wind suction force, the bite connection between the curling edge of the roof slab and the support is the first part to be damaged, and special attention should be paid to the need to take corresponding strengthening measures.
Through the modal analysis of the structure, the first five orders of vibration mode and period are obtained. The time history analysis of the wind pressure on the roof slab was performed to obtain the relative displacement response of the lock joint corresponding to each measuring point. In order to improve the wind-resistance ability of the upright locking metal roofing system and prevent partial overturning, corresponding strengthening countermeasures are proposed according to different engineering conditions. After strengthening the treatment, the use safety of the upright lock-edge metal roofing system is improved, which can provide a reference for engineering design.
After the introduction of the standing seam metal roof system in China, the research on the force transmission principle and the mechanical performance has not been mature, which is not conducive to the popularization and application of such roofing systems. The problems involved in the upright lock-edge metal roofing system are comprehensive and complex, and require a lot of scientific research to solve them. Based on the above problems, this article targeted the relevant research on the crimping joint of the upright edge-sealing metal roof.
First, the structure of the metal roof is introduced. The wind resistance principle of the roof slab is obtained through the preliminary analysis of the structure of the aluminum magnesium manganese upright metal roofing system:the top roof slab is first deformed upward, and the rising force is transmitted to the occlusion structure. The bearing, the bearing then transmits the load from the self-tapping screw to the purlin, and finally distributes it to the main structure. The order of force transmission is wind-absorbing load→roof panel→fixed support→self-tapping screw→purlin→main structure.
Using non-linear finite element software midas FEA to simulate the whole process of the roof system under the wind load, the wind resistance performance of the vertical locking metal roof system was studied. Combined with the domestic research on the metal roofing system's resistance to wind damage, a uniform load of 2 kN/m2 and 5 kN/m2 is applied to the roof slab and vertical ribs, and the stress and stress of the roof slab under different loads are analyzed In the deformation situation, the Mises stress cloud maps at different nodes are obtained. Under the uniform load of 2 kN/m2, the local connection between the support and the metal hemming due to mutual extrusion and slip, the local stress is large, reaching 220 MPa. But at this time, the middle of the slab still stays at a relatively low stress level; under the uniform load of 5 kN/m2, the stress in the middle of the roof slab and the area near the support has reached the yield strength. Under the uniform load of 2 kN/m2, the maximum vertical deflection value of the mid-span position of the roof slab is about 48.18 mm, the deflection value is relatively large, and the opening at the support makes the deflection value of the two sides of the panel surface greater than that of the middle panel Its impact on the overall roofing system usage status. When the value of the uniformly distributed wind load applied to the roof panel is 5 kN/m2, the mid-span deflection is 220 mm. This is because the roof panel has detached from the support, causing the deflection to rapidly increase. At this time, the excessive deflection to normal use of the panel has an unrecoverable impact. By analyzing the deformation of the roof slab under load, it can be seen that the adjacent roof slabs are moved to the two sides by the curling straight ribs under the wind exposure, and the vertical locking part of the roof slab continuously rubs against the aluminum alloy support extrusion, with the continuous development of deformation, eventually detached from the support. Therefore, under the action of the wind suction force, the bite connection between the curling edge of the roof slab and the support is the first part to be damaged, and special attention should be paid to the need to take corresponding strengthening measures.
Through the modal analysis of the structure, the first five orders of vibration mode and period are obtained. The time history analysis of the wind pressure on the roof slab was performed to obtain the relative displacement response of the lock joint corresponding to each measuring point. In order to improve the wind-resistance ability of the upright locking metal roofing system and prevent partial overturning, corresponding strengthening countermeasures are proposed according to different engineering conditions. After strengthening the treatment, the use safety of the upright lock-edge metal roofing system is improved, which can provide a reference for engineering design.
2020, 35(5): 19-26.
doi: 10.13206/j.gjgS255920181109
Abstract:
The roof steel structure of Beijing New Airport Terminal Building has large volume, complicated shape, large span, small number of supporting members and special-shaped columns, which is the key and difficult point of seismic design of the project. The roof on the north of the central hall has larger area and a large overhang, so the center of mass of the overall structure is biased to the north. However, because the roof elevation is higher on the north and lower on the south side, the height of the columns of the curtain wall and the C-shaped columns which Support the north roof is larger, so lateral stiffness is smaller, and the center of stiffness of the overall structure is biased to the south, which will cause the steel structure to twist. By adjusting the layout of the supporting structures, increasing the rigidity of the roof supporting structure on the north, and reducing the rigidity of the roof supporting structure on the south, it can effectively reduce the deviation between the center of mass and stiffness of the structure, improve the torsional stiffness of the structure, and reduce the torsional effect of the structure. The steel structure of the roof of the central hall is composed of six main structural units which are connected by a central lighting dome and six central radiation lighting belts. The structure of the lighting dome and lighting belts is a lighter and thinner truss structure, which is the weaker part of the overall structure by comparing with the six main grid structures. Once the structure of the lighting dome and the lighting belts fail, the overall structure becomes six independent structural units, and each structural unit bears its own regional load independently, which force state is quite different from the overall structure. By checking the bearing capacity of steel members under non-seismic and precautionary intensity seismic combinations for block models of the structure, it shows that even if the central daylighting dome and six daylighting zones fail, the main steel structure still has sufficient bearing capacity and will not collapse.
The lateral stiffness of different kinds of the roof supporting members, such as the C-shaped columns, the steel supporting tubes, the supporting frames of the north curtain wall, independent steel pipe columns and the columns of other curtain walls, is quite different. In order to improve the safety of the whole structure under the action of earthquake, multi-line defense analysis is performed. Considering that the roof steel structure of the project is a large-span spatial structure, it is reasonable that the roof supporting members can bear the seismic force generated by their respective load mass. By analyzing of the proportion of the gravity load and seismic shear force of the roof supporting members, the seismic shear force of the roof supporting member bearing a less proportion of seismic shear force than its gravity load is adjusted according to its proportion of gravity load to improve the seismic resistance of multi-line defense of the whole structure.
By seting up the dynamic elastoplastic time-history analysis model of the central hall structure, the elastoplastic time-history analysis of the whole structure is performed under rare earthquakes to discuss the plastic deformation and development degree of the roof supporting steel structures and the concrete structures. It shows that some members enter the elastoplastic working state with their strength and rigidity deteriorated, but the degree of degradation is not large, and the whole structure has sufficient capacity for redistribution of internal forces to maintain its overall stability and bear earthquake action and gravity loads.
The roof steel structure of Beijing New Airport Terminal Building has large volume, complicated shape, large span, small number of supporting members and special-shaped columns, which is the key and difficult point of seismic design of the project. The roof on the north of the central hall has larger area and a large overhang, so the center of mass of the overall structure is biased to the north. However, because the roof elevation is higher on the north and lower on the south side, the height of the columns of the curtain wall and the C-shaped columns which Support the north roof is larger, so lateral stiffness is smaller, and the center of stiffness of the overall structure is biased to the south, which will cause the steel structure to twist. By adjusting the layout of the supporting structures, increasing the rigidity of the roof supporting structure on the north, and reducing the rigidity of the roof supporting structure on the south, it can effectively reduce the deviation between the center of mass and stiffness of the structure, improve the torsional stiffness of the structure, and reduce the torsional effect of the structure. The steel structure of the roof of the central hall is composed of six main structural units which are connected by a central lighting dome and six central radiation lighting belts. The structure of the lighting dome and lighting belts is a lighter and thinner truss structure, which is the weaker part of the overall structure by comparing with the six main grid structures. Once the structure of the lighting dome and the lighting belts fail, the overall structure becomes six independent structural units, and each structural unit bears its own regional load independently, which force state is quite different from the overall structure. By checking the bearing capacity of steel members under non-seismic and precautionary intensity seismic combinations for block models of the structure, it shows that even if the central daylighting dome and six daylighting zones fail, the main steel structure still has sufficient bearing capacity and will not collapse.
The lateral stiffness of different kinds of the roof supporting members, such as the C-shaped columns, the steel supporting tubes, the supporting frames of the north curtain wall, independent steel pipe columns and the columns of other curtain walls, is quite different. In order to improve the safety of the whole structure under the action of earthquake, multi-line defense analysis is performed. Considering that the roof steel structure of the project is a large-span spatial structure, it is reasonable that the roof supporting members can bear the seismic force generated by their respective load mass. By analyzing of the proportion of the gravity load and seismic shear force of the roof supporting members, the seismic shear force of the roof supporting member bearing a less proportion of seismic shear force than its gravity load is adjusted according to its proportion of gravity load to improve the seismic resistance of multi-line defense of the whole structure.
By seting up the dynamic elastoplastic time-history analysis model of the central hall structure, the elastoplastic time-history analysis of the whole structure is performed under rare earthquakes to discuss the plastic deformation and development degree of the roof supporting steel structures and the concrete structures. It shows that some members enter the elastoplastic working state with their strength and rigidity deteriorated, but the degree of degradation is not large, and the whole structure has sufficient capacity for redistribution of internal forces to maintain its overall stability and bear earthquake action and gravity loads.
2020, 35(5): 27-33.
doi: 10.13206/j.gjgS20021801
Abstract:
The concrete-filled stainless steel tubular (CFSST) structure combines the good mechanical properties of conventional concrete filled carbon steel columns and superior durability. Not only is the construction cost relatively reduced because of its infusion of concrete, but also when it is applied to offshore platforms, seaside buildings, bridges and super high-rise buildings, the later maintenance costs are also significantly reduced compared to conventional concrete——filled carbon steel tube structures. The CFSST structures have been used in actual engineering projects such as Stonecutters Bridge in Hong Kong and Hearst Tower in New York.
The existing specifications for the load bearing capacity of concrete filled steel tubular (CFST) columns, mainly due to the fact that the strain hardening characteristic of stainless steel is not beneficially considered, are all conservative. In order to make sure that the CFSST structures can be accurately evaluated in actual engineering projects, combined with the loading conditions of the circular CFSST beam-columns, the design method of calculating bearing capacity for circular CFSST beam columns is analysed. The existing Chinese national standard GB 50936-2014 Technical Specifications for Concrete Filled-Steel Tubular Structure, the local standard of Fujian Province DBJ/T 13-51-2010 Technical Specifications for Concrete-Filled Steel Tubular Structure, European Code Eurocode 4, and American Steel Structure Association Code ANSI/AISC 360 were used to calculate the bearing capacity of the collected 40 circular CFSST beam columns, and the calculated bearing capacity and the measured bearing capacity are compared:the average and variance of the calculated bearing capacity and the measured value of GB 50936 are respectively 0.871 and 0.105, the average and variance of the calculated and measured values' ratio of the bearing capacity in DBJ/T are respectively 0.868 and 0.073, the average and variance of the calculated and measured ratios of the EC4 specifications are 0.832 and 0.067, respectively. The average and variance of the calculated and measured values of the bearing capacity of the AISC specification are 0.612 and 0.122, respectively.
In view of the fact that the bearing capacity results of circular CFSST beam columns calculated by the above existing codes or specifications are all conservative, using finite element software, a finite element model of circular CFSST beam-column was established. On the basis of verifying the correctness of the model, the influence of grade of stainless steel, section steel ratio, core concrete strength and slenderness ratio on the axial force-bending moment correlation curve was conducted. The results show that the larger stainless steel yield strength and section steel ratio, the smaller abscissa and ordinate values of the equilibrium point in the axial force-bending moment correlation curve; the greater the strength of core concrete, the larger abscissa and ordinate values of the equilibrium point in the axial force-bending moment correlation curve. As the slenderness ratio increases, the the axial force-bending moment correlation curve tends to a straight line.
Finally, on the basis of the relative axial force-bending moment strength correlation equation of the circular CFST beam-columns recommended by the DBJ/T specification, the relationship between the equilibrium point coordinate value and the constraint coefficient is derived to apply for calculating bearing capacity of circular CFSST beam-columns.The simplified calculation formula of the circular concrete-filled stainless steel tubular bending capacity is more appropriate than the calculation formula of the existing codes or specifications, the calculated bearing capacity is closer to the actual measured value, and provide a reference for the engineering design of CFSST, and also provide a basis for the compilation of relevant codes or specifications.
The concrete-filled stainless steel tubular (CFSST) structure combines the good mechanical properties of conventional concrete filled carbon steel columns and superior durability. Not only is the construction cost relatively reduced because of its infusion of concrete, but also when it is applied to offshore platforms, seaside buildings, bridges and super high-rise buildings, the later maintenance costs are also significantly reduced compared to conventional concrete——filled carbon steel tube structures. The CFSST structures have been used in actual engineering projects such as Stonecutters Bridge in Hong Kong and Hearst Tower in New York.
The existing specifications for the load bearing capacity of concrete filled steel tubular (CFST) columns, mainly due to the fact that the strain hardening characteristic of stainless steel is not beneficially considered, are all conservative. In order to make sure that the CFSST structures can be accurately evaluated in actual engineering projects, combined with the loading conditions of the circular CFSST beam-columns, the design method of calculating bearing capacity for circular CFSST beam columns is analysed. The existing Chinese national standard GB 50936-2014 Technical Specifications for Concrete Filled-Steel Tubular Structure, the local standard of Fujian Province DBJ/T 13-51-2010 Technical Specifications for Concrete-Filled Steel Tubular Structure, European Code Eurocode 4, and American Steel Structure Association Code ANSI/AISC 360 were used to calculate the bearing capacity of the collected 40 circular CFSST beam columns, and the calculated bearing capacity and the measured bearing capacity are compared:the average and variance of the calculated bearing capacity and the measured value of GB 50936 are respectively 0.871 and 0.105, the average and variance of the calculated and measured values' ratio of the bearing capacity in DBJ/T are respectively 0.868 and 0.073, the average and variance of the calculated and measured ratios of the EC4 specifications are 0.832 and 0.067, respectively. The average and variance of the calculated and measured values of the bearing capacity of the AISC specification are 0.612 and 0.122, respectively.
In view of the fact that the bearing capacity results of circular CFSST beam columns calculated by the above existing codes or specifications are all conservative, using finite element software, a finite element model of circular CFSST beam-column was established. On the basis of verifying the correctness of the model, the influence of grade of stainless steel, section steel ratio, core concrete strength and slenderness ratio on the axial force-bending moment correlation curve was conducted. The results show that the larger stainless steel yield strength and section steel ratio, the smaller abscissa and ordinate values of the equilibrium point in the axial force-bending moment correlation curve; the greater the strength of core concrete, the larger abscissa and ordinate values of the equilibrium point in the axial force-bending moment correlation curve. As the slenderness ratio increases, the the axial force-bending moment correlation curve tends to a straight line.
Finally, on the basis of the relative axial force-bending moment strength correlation equation of the circular CFST beam-columns recommended by the DBJ/T specification, the relationship between the equilibrium point coordinate value and the constraint coefficient is derived to apply for calculating bearing capacity of circular CFSST beam-columns.The simplified calculation formula of the circular concrete-filled stainless steel tubular bending capacity is more appropriate than the calculation formula of the existing codes or specifications, the calculated bearing capacity is closer to the actual measured value, and provide a reference for the engineering design of CFSST, and also provide a basis for the compilation of relevant codes or specifications.
2020, 35(5): 34-49.
doi: 10.13206/j.gjgS20041301
Abstract:
The welding is the main connecting method for steel structures. Every country in the world has published corresponding technical standards to regulate the design and construction requirements on welded connection design. This paper summarizes and compares the basic requirements and design methods for welded connections of steel structure in the current Chinese Standard for Design of Steel Structures(GB 50017-2017), American Specification for Structural Steel Buildings(AISC 360-16) and affiliated technical specifications, analyzes and discusses welding types, detailing requirements, quality inspection, resistance calculations and other provisions specified in GB 50017-2017 and AISC 360-16 and relevant technical specifications. The paper is focuses on the differences and similarities between the technical standards of the two countries, and the main contents are:
1)Technical standards on welded connections. The design provisions on welded connections in the United States is regulated by various professional society. The American Welding Society has released the AWS standards for welding materials and welding processes. The American Society for Testing and Materials has provided the ASTM standards for structural steel and connection materials. The American Institute of Steel Construction has formulated the AISC standard for determining resistance and requirements of welded connections. However, the welded connection design in China should be in accordance with the national GB standard or JGJ standard published by the Chinese government.
2)Types of welded connection. The types of welded connections recommended by GB 50017 and AISC 360 are more or less the same, including fully penetrated butt weld, partially penetrated butt weld, fillet weld, plug weld and slot weld. The detailed requirements in the two standards for various types of welded connections are basically similar.
3)Design principle of welded connections. GB 50017 requires to follow Limit State Design to determine the resistance of various welded connections, while AISC 360 allows structural engineers to take Allowable Strength Design or Load and Resistance Factors Design, which is equivalent to Limit State Design, to determine the resistance of welded connections.
4)Analysis of butt welds. GB 50017 determines the resistance of fully penetrated butt weld according to the specified design strength of butt weld, while AISC 360 assumes the strength of welding equal to the parent metal as long as the details, welding process and quality inspection satisfying the requirements. For the resistance of partially penetrated butt weld, the calculation method equivalent to fillet weld is applied in both standards.
5)Analysis of fillet weld. The methods to determine the resistance of fillet weld, plug weld and slot weld specified in GB 50017 and AISC 360 are fundamentally identical, but the resistance of fillet weld given by AISC 360 is slightly higher than that of GB 50017. Both standards apply a reduction factor to consider the shear force distribution in long fillet weld.
Above all, this paper provides a guide for structural engineers to understand and apply GB 50017 and AISC 360 efficiently. Some suggestions and recommendations are also proposed for further improving GB 50017-2017.
The welding is the main connecting method for steel structures. Every country in the world has published corresponding technical standards to regulate the design and construction requirements on welded connection design. This paper summarizes and compares the basic requirements and design methods for welded connections of steel structure in the current Chinese Standard for Design of Steel Structures(GB 50017-2017), American Specification for Structural Steel Buildings(AISC 360-16) and affiliated technical specifications, analyzes and discusses welding types, detailing requirements, quality inspection, resistance calculations and other provisions specified in GB 50017-2017 and AISC 360-16 and relevant technical specifications. The paper is focuses on the differences and similarities between the technical standards of the two countries, and the main contents are:
1)Technical standards on welded connections. The design provisions on welded connections in the United States is regulated by various professional society. The American Welding Society has released the AWS standards for welding materials and welding processes. The American Society for Testing and Materials has provided the ASTM standards for structural steel and connection materials. The American Institute of Steel Construction has formulated the AISC standard for determining resistance and requirements of welded connections. However, the welded connection design in China should be in accordance with the national GB standard or JGJ standard published by the Chinese government.
2)Types of welded connection. The types of welded connections recommended by GB 50017 and AISC 360 are more or less the same, including fully penetrated butt weld, partially penetrated butt weld, fillet weld, plug weld and slot weld. The detailed requirements in the two standards for various types of welded connections are basically similar.
3)Design principle of welded connections. GB 50017 requires to follow Limit State Design to determine the resistance of various welded connections, while AISC 360 allows structural engineers to take Allowable Strength Design or Load and Resistance Factors Design, which is equivalent to Limit State Design, to determine the resistance of welded connections.
4)Analysis of butt welds. GB 50017 determines the resistance of fully penetrated butt weld according to the specified design strength of butt weld, while AISC 360 assumes the strength of welding equal to the parent metal as long as the details, welding process and quality inspection satisfying the requirements. For the resistance of partially penetrated butt weld, the calculation method equivalent to fillet weld is applied in both standards.
5)Analysis of fillet weld. The methods to determine the resistance of fillet weld, plug weld and slot weld specified in GB 50017 and AISC 360 are fundamentally identical, but the resistance of fillet weld given by AISC 360 is slightly higher than that of GB 50017. Both standards apply a reduction factor to consider the shear force distribution in long fillet weld.
Above all, this paper provides a guide for structural engineers to understand and apply GB 50017 and AISC 360 efficiently. Some suggestions and recommendations are also proposed for further improving GB 50017-2017.
