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Steel Construction Published the List of Highly Influential Articles of 2020
2023 Vol. 38, No. 10
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2023, 38(10): 1-9.
doi: 10.13206/j.gjgs23080402
Abstract
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Abstract:
Large-span space structures are widely used in large public buildings such as terminal buildings, high-speed railway stations and exhibition centers, which have intensive population and enormous investment. It is necessary not only to ensure their seismic safety under earthquakes, but also to consider their potential seismic damage and economic losses, that is, to carry out performance-based seismic design. The basic principles of seismic performance design in China′s Code for Seismic Design of Buildings(GB 50011-2010) are mainly based on concrete structures and not suitable for large-span space structures. Therefore, in this paper, taking single-layer spherical reticulated shells, single-layer cylindrical reticulated shells and trusses as examples, the finite element method is used to analyze their seismic response characteristics and failure modes, determine suitable seismic damage evaluation indexes, classify their seismic damage levels, and provide support for performance-based seismic design of large-span space structures. According to the Technical Specification of Space Frame Structures(JGJ 7-2010), 15 single-layer spherical reticulated shells, 9 single-layer cylindrical reticulated shells and 16 tubular trusses with different spans and rise-to-span ratios were designed by using the design software 3D3S. The finite element software ABAQUS was used to establish the finite element models of these structures. According to the Code for Seismic Design of Buildings, 34 ground motions conforming to the target response spectra of structures were selected from the ground motion database of Pacific Earthquake Engineering Research Center, and the ground motions were three-directionally scaled in a 1∶0.85∶0.65 ratio. The responses of the structures under different ground motions with different intensities are analyzed, and the seismic response characteristics and failure modes of the structures are summarized.
The results show that for single-layer spherical reticulated shells, the maximum displacement of nodes changes significantly with the seismic intensity, and the plastic strain energy can fully reflect the damage levels of the structure. Therefore, two parameters, the maximum displacement of nodes and the plastic strain energy reflecting the earthquake damage degree, are used as the seismic damage evaluation indexes of the structure, based on which the damage index is formed using different weights, and the seismic damage classification criteria are proposed for single-layer spherical reticulated shell structures according to the damage index. For single-layer cylindrical reticulated shells, the structural deformations of the structures in the secondary static analysis are similar to the seismic displacement responses, indicating that the damage of the structure under static loads is the further development on the basis of the seismic damage. Therefore, the static ultimate bearing capacities of the structure before and after earthquakes are used as the evaluation indexes of structural seismic damage. Based on the damage index considering the change of the static ultimate bearing capacity, the classification criteria of seismic damage for single-layer cylindrical reticulated shells are proposed. For the tubular trusses, large plastic deformations occur in the mid-span and near-support areas of the main truss, and the structural stiffness is significantly reduced. The plastic strain is used as the seismic damage evaluation index of the rods with large plastic deformation, and the damage levels of the rods are classified. According to the proportions of the rods with different damage levels, the seismic damage classification criteria for the tubular trusses is proposed. For both the single-layer spherical reticulated shell and single-layer cylindrical reticulated shell, the ratios of the maximum displacement to span are positively correlated with the damage indexes. Therefore, the seismic damage levels of these two types of structures can be classified according to the ratio of the maximum displacement to span, which is simpler and faster.
Large-span space structures are widely used in large public buildings such as terminal buildings, high-speed railway stations and exhibition centers, which have intensive population and enormous investment. It is necessary not only to ensure their seismic safety under earthquakes, but also to consider their potential seismic damage and economic losses, that is, to carry out performance-based seismic design. The basic principles of seismic performance design in China′s Code for Seismic Design of Buildings(GB 50011-2010) are mainly based on concrete structures and not suitable for large-span space structures. Therefore, in this paper, taking single-layer spherical reticulated shells, single-layer cylindrical reticulated shells and trusses as examples, the finite element method is used to analyze their seismic response characteristics and failure modes, determine suitable seismic damage evaluation indexes, classify their seismic damage levels, and provide support for performance-based seismic design of large-span space structures. According to the Technical Specification of Space Frame Structures(JGJ 7-2010), 15 single-layer spherical reticulated shells, 9 single-layer cylindrical reticulated shells and 16 tubular trusses with different spans and rise-to-span ratios were designed by using the design software 3D3S. The finite element software ABAQUS was used to establish the finite element models of these structures. According to the Code for Seismic Design of Buildings, 34 ground motions conforming to the target response spectra of structures were selected from the ground motion database of Pacific Earthquake Engineering Research Center, and the ground motions were three-directionally scaled in a 1∶0.85∶0.65 ratio. The responses of the structures under different ground motions with different intensities are analyzed, and the seismic response characteristics and failure modes of the structures are summarized.
The results show that for single-layer spherical reticulated shells, the maximum displacement of nodes changes significantly with the seismic intensity, and the plastic strain energy can fully reflect the damage levels of the structure. Therefore, two parameters, the maximum displacement of nodes and the plastic strain energy reflecting the earthquake damage degree, are used as the seismic damage evaluation indexes of the structure, based on which the damage index is formed using different weights, and the seismic damage classification criteria are proposed for single-layer spherical reticulated shell structures according to the damage index. For single-layer cylindrical reticulated shells, the structural deformations of the structures in the secondary static analysis are similar to the seismic displacement responses, indicating that the damage of the structure under static loads is the further development on the basis of the seismic damage. Therefore, the static ultimate bearing capacities of the structure before and after earthquakes are used as the evaluation indexes of structural seismic damage. Based on the damage index considering the change of the static ultimate bearing capacity, the classification criteria of seismic damage for single-layer cylindrical reticulated shells are proposed. For the tubular trusses, large plastic deformations occur in the mid-span and near-support areas of the main truss, and the structural stiffness is significantly reduced. The plastic strain is used as the seismic damage evaluation index of the rods with large plastic deformation, and the damage levels of the rods are classified. According to the proportions of the rods with different damage levels, the seismic damage classification criteria for the tubular trusses is proposed. For both the single-layer spherical reticulated shell and single-layer cylindrical reticulated shell, the ratios of the maximum displacement to span are positively correlated with the damage indexes. Therefore, the seismic damage levels of these two types of structures can be classified according to the ratio of the maximum displacement to span, which is simpler and faster.
2023, 38(10): 10-15.
doi: 10.13206/j.gjgs23081201
Abstract:
Large and complex steel structures have the characteristics of a large number of structural components, a large workload of welding and bolting, and multiple construction processes. Traditional preassembly methods not only have high costs and low efficiency, making it difficult to meet the requirements of large and complex spatial structures. To address this issue, a pre-assembly method for large and complex steel structures based on BIM and 3D laser scanning technology is proposed. Taking the Western(Chongqing) Science Hall project as the engineering background, the intelligent construction process of roof circular pipe truss and large-span floor truss was studied, and the technical route and method flow were proposed. A benchmark extraction method based on random sampling consistency algorithm and Laplacian rolling ball hybrid detection algorithm is proposed for common circular pipe trusses. A directed bounding box method is suggested to obtain the registration reference points for the regular shaped I-shaped steel truss and bracket point cloud. To obtain construction quality inspection data, k-nearest neighbor algorithm, principal component analysis algorithm, and edge detection algorithm based on region criteria to intelligently extract interface corners are suggested.
The results indicate that the combination of BIM and 3D laser scanning technology has achieved relatively accurate results in virtual pre assembly of circular tube trusses and I-shaped beam trusses; The cylindrical truss reference points obtained using the proposed method, combined with the full arrangement algorithm of the reference points and the iterative nearest neighbor algorithm, can achieve high registration quality.
Large and complex steel structures have the characteristics of a large number of structural components, a large workload of welding and bolting, and multiple construction processes. Traditional preassembly methods not only have high costs and low efficiency, making it difficult to meet the requirements of large and complex spatial structures. To address this issue, a pre-assembly method for large and complex steel structures based on BIM and 3D laser scanning technology is proposed. Taking the Western(Chongqing) Science Hall project as the engineering background, the intelligent construction process of roof circular pipe truss and large-span floor truss was studied, and the technical route and method flow were proposed. A benchmark extraction method based on random sampling consistency algorithm and Laplacian rolling ball hybrid detection algorithm is proposed for common circular pipe trusses. A directed bounding box method is suggested to obtain the registration reference points for the regular shaped I-shaped steel truss and bracket point cloud. To obtain construction quality inspection data, k-nearest neighbor algorithm, principal component analysis algorithm, and edge detection algorithm based on region criteria to intelligently extract interface corners are suggested.
The results indicate that the combination of BIM and 3D laser scanning technology has achieved relatively accurate results in virtual pre assembly of circular tube trusses and I-shaped beam trusses; The cylindrical truss reference points obtained using the proposed method, combined with the full arrangement algorithm of the reference points and the iterative nearest neighbor algorithm, can achieve high registration quality.
2023, 38(10): 16-24.
doi: 10.13206/j.gjgs23051701
Abstract:
For the typical bridge weathering steel in practical engineering as the object, the change laws of the surface morphology, phase composition, corrosion weight loss, dynamic curve and electrochemical properties of the rust layer of weathering steel were studied through periodic immersion accelerated corrosion test, and the macro morphology observation method, scanning electron microscope(SEM), X-ray diffraction analysis(XRD) and other methods, The corrosion behavior of Q345qDNH typical weathering steel under simulated industrial marine atmospheric environment NaHSO3 and different NaCl concentrations was investigated.
The results show that the corrosion products on the surface of weathering steel are mainly composed of α-FeOOH, γ-FeOOH, β-FeOOH, Fe2O3, Fe3O4, and the NaCl concentration in the corrosion environment is positively related to the corrosion weight loss rate of weathering steel. When the concentration of NaCl is 0.1%, the corrosion weight loss rate of weathering steel rapidly drops to the low position with the extension of corrosion time and then tends to be stable. After 1 440 h of corrosion, the surface of the rust layer is uniform and dense, and the average corrosion weight loss rate is about 0.76 g/(cm2·h); when the NaCl ion concentration in the corrosion environment is 3.5%, the corrosion weight loss rate of weathering steel is at a high level and increases first and then decreases with the extension of corrosion time. After 1 440 h of corrosion, there are many cracks and holes on the surface of the rust layer, and the average corrosion weight loss rate is about 0.89 g/(cm2·h). Therefore, the lower the NaCl concentration, the more positive the self corrosion potential of weathering steel, the smaller the self corrosion current density and the slower the corrosion weight loss rate. The self corrosion current density of weathering steel is 105.65 μA/mm2 after being corroded for 1 440 h in the environment with 0.1%NaCl concentration, in the rust layer α-FeOOH/(β-FeOOH+γ-FeOOH) ratio is close to 2, much higher than 0.104 in 3.5%NaCl concentration. At this time, the state of rust layer tends to be stable, and it has a good protection effect on weathering steel matrix.
For the typical bridge weathering steel in practical engineering as the object, the change laws of the surface morphology, phase composition, corrosion weight loss, dynamic curve and electrochemical properties of the rust layer of weathering steel were studied through periodic immersion accelerated corrosion test, and the macro morphology observation method, scanning electron microscope(SEM), X-ray diffraction analysis(XRD) and other methods, The corrosion behavior of Q345qDNH typical weathering steel under simulated industrial marine atmospheric environment NaHSO3 and different NaCl concentrations was investigated.
The results show that the corrosion products on the surface of weathering steel are mainly composed of α-FeOOH, γ-FeOOH, β-FeOOH, Fe2O3, Fe3O4, and the NaCl concentration in the corrosion environment is positively related to the corrosion weight loss rate of weathering steel. When the concentration of NaCl is 0.1%, the corrosion weight loss rate of weathering steel rapidly drops to the low position with the extension of corrosion time and then tends to be stable. After 1 440 h of corrosion, the surface of the rust layer is uniform and dense, and the average corrosion weight loss rate is about 0.76 g/(cm2·h); when the NaCl ion concentration in the corrosion environment is 3.5%, the corrosion weight loss rate of weathering steel is at a high level and increases first and then decreases with the extension of corrosion time. After 1 440 h of corrosion, there are many cracks and holes on the surface of the rust layer, and the average corrosion weight loss rate is about 0.89 g/(cm2·h). Therefore, the lower the NaCl concentration, the more positive the self corrosion potential of weathering steel, the smaller the self corrosion current density and the slower the corrosion weight loss rate. The self corrosion current density of weathering steel is 105.65 μA/mm2 after being corroded for 1 440 h in the environment with 0.1%NaCl concentration, in the rust layer α-FeOOH/(β-FeOOH+γ-FeOOH) ratio is close to 2, much higher than 0.104 in 3.5%NaCl concentration. At this time, the state of rust layer tends to be stable, and it has a good protection effect on weathering steel matrix.
2023, 38(10): 25-31.
doi: 10.13206/j.gjgS23102401
Abstract:
The engineering application scenarios are becoming more and more complex, and the structure is facing higher requirements in terms of bearing capacity, corrosion resistance and economy. It is difficult for a single metal material to meet all engineering requirements. Stainless steel is a kind of green high-performance material, which is conducive to the realization of the goal of ‘double carbon’ in China, and has good strength and corrosion resistance. Carbon steel is widely used because of its low price, but its corrosion resistance is poor. In order to improve the utilization of materials and save costs, stainless steel and carbon steel are often welded in engineering. At present, due to the different working environment and working medium of the equipment in the nuclear power plant, austenitic stainless steel and carbon steel are usually used for welding; in the building curtain wall, the general outdoor wall panels, connectors, glass curtain wall support system will use stainless steel, while the internal keel and the theme steel truss column will use carbon steel, so there will be a large number of stainless steel and carbon steel welding. However, the current domestic specifications do not support the welding of stainless steel and carbon steel. Due to the different chemical composition and physical properties of the two materials, the welding of stainless steel and carbon steel encounters problems. For example, the difference in melting point causes metal loss, the difference in linear expansion coefficient may lead to cracks in the weld, and the difference in chemical composition causes brittle compounds in the welding process. Since the existing research mainly focuses on the welding of Q235B steel and austenitic stainless steel, there is no systematic study on the common types of stainless steel and carbon steel. The S30408, QN1803, S22053 stainless steel and Q235B, Q355B carbon steel are connected by butt weld. The mechanical properties such as metallographic structure, hardness, strength and fracture morphology of 6 different combinations and 48 stainless steel and carbon steel welded joints were systematically studied through experiments. The results show that there are obvious carburized layer and decarburized layer in the welded joint of stainless steel and carbon steel near the fusion line. The grain size of the heat affected zone increases, and the brittle structure such as martensite appears, so that the hardness of the heat affected zone is greater than that of the metal base metal. The tensile specimens of stainless steel and carbon steel welded joints fractured on the side of carbon steel. The tensile strength was consistent with the tensile strength of the carbon steel base metal. The yield strength was lower than that of the carbon steel base metal, and the elongation was significantly reduced. Due to the formation of decarburized layer, the hardness and toughness near the fusion line of carbon steel decrease, the tensile fractures of stainless steel and carbon steel welded joints show dimples, which are ductile fractures.
The engineering application scenarios are becoming more and more complex, and the structure is facing higher requirements in terms of bearing capacity, corrosion resistance and economy. It is difficult for a single metal material to meet all engineering requirements. Stainless steel is a kind of green high-performance material, which is conducive to the realization of the goal of ‘double carbon’ in China, and has good strength and corrosion resistance. Carbon steel is widely used because of its low price, but its corrosion resistance is poor. In order to improve the utilization of materials and save costs, stainless steel and carbon steel are often welded in engineering. At present, due to the different working environment and working medium of the equipment in the nuclear power plant, austenitic stainless steel and carbon steel are usually used for welding; in the building curtain wall, the general outdoor wall panels, connectors, glass curtain wall support system will use stainless steel, while the internal keel and the theme steel truss column will use carbon steel, so there will be a large number of stainless steel and carbon steel welding. However, the current domestic specifications do not support the welding of stainless steel and carbon steel. Due to the different chemical composition and physical properties of the two materials, the welding of stainless steel and carbon steel encounters problems. For example, the difference in melting point causes metal loss, the difference in linear expansion coefficient may lead to cracks in the weld, and the difference in chemical composition causes brittle compounds in the welding process. Since the existing research mainly focuses on the welding of Q235B steel and austenitic stainless steel, there is no systematic study on the common types of stainless steel and carbon steel. The S30408, QN1803, S22053 stainless steel and Q235B, Q355B carbon steel are connected by butt weld. The mechanical properties such as metallographic structure, hardness, strength and fracture morphology of 6 different combinations and 48 stainless steel and carbon steel welded joints were systematically studied through experiments. The results show that there are obvious carburized layer and decarburized layer in the welded joint of stainless steel and carbon steel near the fusion line. The grain size of the heat affected zone increases, and the brittle structure such as martensite appears, so that the hardness of the heat affected zone is greater than that of the metal base metal. The tensile specimens of stainless steel and carbon steel welded joints fractured on the side of carbon steel. The tensile strength was consistent with the tensile strength of the carbon steel base metal. The yield strength was lower than that of the carbon steel base metal, and the elongation was significantly reduced. Due to the formation of decarburized layer, the hardness and toughness near the fusion line of carbon steel decrease, the tensile fractures of stainless steel and carbon steel welded joints show dimples, which are ductile fractures.
2023, 38(10): 32-41.
doi: 10.13206/j.gjgs23072802
Abstract:
Carbon peaking and carbon neutrality goals are important national policies which will guide the direction of economic development. Since the proportion of carbon emission caused by construction industry is considerable, the degree of carbon emission control in each link of the industry is directly related to the success or failure of the overall double carbon control objectives. Reduction of building material cost is one of the most efficient ways to meet double carbon goals, and it requires that more advanced design method and conception should be employed in structural design. However, the safety of the structure exposed to seismic action is another important issue in design process. Structural reinforcement for the structure itself is the most conventional way to reduce the earthquake hazards, but it would result in the increase of the cost of building materials. In order to resolve the contraction, it is necessary to make more efforts for optimizing the design conception.
In this paper, the relationship between seismic design and double carbon goals is discussed, and some conclusions about the novel seismic design conception based on double goals are given. On the one hand, it is suggested that different seismic design strategy should be employed in the design of the structures in different earthquake zones. For the structure in the low seismic intensity area(6 degrees and below) and some medium seismic intensity area(7 degrees) where the seismic combination condition does not play a controlling role, the requirements of structural ductility can be reduced, and the seismic safety can be achieved by improving the seismic bearing capacity. For the structure in the high seismic intensity area(8 degrees and above) and some moderate intensity area(7 degrees) where the seismic combination conditions play a controlling role, some structural systems meeting the double goal conception could be adopted, such as double seismic resistance structure, self-centering structure and rocking structure, etc., and the seismic cost of the structure itself should be reduced by means of increasing energy consumption and isolation. On the other hand, it is supposed to use IO state to represent the seismic design objective. It is not advisable to overdesign the elastic anti-seismic capacity for the buildings specified in the No. 744 regulation file. Some low-level plastic deformation should be allowed in medium intensity earthquake, and IO state could be used to describe the threshold of allowable plastic deformation.
Carbon peaking and carbon neutrality goals are important national policies which will guide the direction of economic development. Since the proportion of carbon emission caused by construction industry is considerable, the degree of carbon emission control in each link of the industry is directly related to the success or failure of the overall double carbon control objectives. Reduction of building material cost is one of the most efficient ways to meet double carbon goals, and it requires that more advanced design method and conception should be employed in structural design. However, the safety of the structure exposed to seismic action is another important issue in design process. Structural reinforcement for the structure itself is the most conventional way to reduce the earthquake hazards, but it would result in the increase of the cost of building materials. In order to resolve the contraction, it is necessary to make more efforts for optimizing the design conception.
In this paper, the relationship between seismic design and double carbon goals is discussed, and some conclusions about the novel seismic design conception based on double goals are given. On the one hand, it is suggested that different seismic design strategy should be employed in the design of the structures in different earthquake zones. For the structure in the low seismic intensity area(6 degrees and below) and some medium seismic intensity area(7 degrees) where the seismic combination condition does not play a controlling role, the requirements of structural ductility can be reduced, and the seismic safety can be achieved by improving the seismic bearing capacity. For the structure in the high seismic intensity area(8 degrees and above) and some moderate intensity area(7 degrees) where the seismic combination conditions play a controlling role, some structural systems meeting the double goal conception could be adopted, such as double seismic resistance structure, self-centering structure and rocking structure, etc., and the seismic cost of the structure itself should be reduced by means of increasing energy consumption and isolation. On the other hand, it is supposed to use IO state to represent the seismic design objective. It is not advisable to overdesign the elastic anti-seismic capacity for the buildings specified in the No. 744 regulation file. Some low-level plastic deformation should be allowed in medium intensity earthquake, and IO state could be used to describe the threshold of allowable plastic deformation.
2023, 38(10): 42-48.
doi: 10.13206/j.gjgS23080401
Abstract:
Xiatian Sports Park Stadium is located in Dehua County, Quanzhou City, Fujian Province. Its structure consists of a reinforced concrete frame stand in the lower part and a single-layer cable net in the upper part. The single-layer cable net is in a saddle-shaped hyperboloid form, the bearing cables which are concave downwards are arranged along the successive directions of the stand, the wind-resistant cables which are convex upwards are arranged along the left and right directions of the stand, the bearing cables and the wind-resistant cables are mutually connected through cable clamps, and the anti-slip capability of the cable clamps ensures that the bearing cables and the wind-resistant cables do not slip at the intersection positions. The upper single-layer cable net adopts a rigid and flexible mixed boundary constraint form. A rigid boundary is a floor-type steel arch support on a steel inclined column above that stand, and a flexible boundary is compose of a hoop cable supported on a steel mast in front of the stand and side cables supported on the steel mast and a foundation at two side of the stand. The bearing cable and the wind-resistant cable are arranged orthogonally on the projection plane, and the spacing in the projection direction is about 7 m. Because the single-layer cable net is a fully flexible structural system, the structural stiffness is zero and can not bear any load before the prestress is applied. Therefore, the form-finding analysis of the cable net must be carried out according to the expected shape of the building before the calculation and analysis of the cable net. The shape of the cable net and the initial stress state are determined by the form-finding of the cable net, and the cable net with the initial stress state has the ability to bear the external load. After the form-finding analysis of the cable net is completed, the static calculation, the small earthquake elastic calculation and the large earthquake elastic-plastic calculation of the cable net can be carried out according to different loads and action conditions. Through several rounds of optimization and calculation, the boundary conditions and three-dimensional shape of the flexible cable net are determined, and by using the basic principles of the force density method and the extended force density method, the basic program for the form-finding of the complex cable net is compiled and finally used in this project with good results; The bearing capacity and deformation of key joints are checked by three-dimensional finite element analysis and anti-slip test. The above analysis results show that the structural selection of the single-layer cable net of this project is basically reasonable, and the design results meet the requirements of the current national specifications.
Xiatian Sports Park Stadium is located in Dehua County, Quanzhou City, Fujian Province. Its structure consists of a reinforced concrete frame stand in the lower part and a single-layer cable net in the upper part. The single-layer cable net is in a saddle-shaped hyperboloid form, the bearing cables which are concave downwards are arranged along the successive directions of the stand, the wind-resistant cables which are convex upwards are arranged along the left and right directions of the stand, the bearing cables and the wind-resistant cables are mutually connected through cable clamps, and the anti-slip capability of the cable clamps ensures that the bearing cables and the wind-resistant cables do not slip at the intersection positions. The upper single-layer cable net adopts a rigid and flexible mixed boundary constraint form. A rigid boundary is a floor-type steel arch support on a steel inclined column above that stand, and a flexible boundary is compose of a hoop cable supported on a steel mast in front of the stand and side cables supported on the steel mast and a foundation at two side of the stand. The bearing cable and the wind-resistant cable are arranged orthogonally on the projection plane, and the spacing in the projection direction is about 7 m. Because the single-layer cable net is a fully flexible structural system, the structural stiffness is zero and can not bear any load before the prestress is applied. Therefore, the form-finding analysis of the cable net must be carried out according to the expected shape of the building before the calculation and analysis of the cable net. The shape of the cable net and the initial stress state are determined by the form-finding of the cable net, and the cable net with the initial stress state has the ability to bear the external load. After the form-finding analysis of the cable net is completed, the static calculation, the small earthquake elastic calculation and the large earthquake elastic-plastic calculation of the cable net can be carried out according to different loads and action conditions. Through several rounds of optimization and calculation, the boundary conditions and three-dimensional shape of the flexible cable net are determined, and by using the basic principles of the force density method and the extended force density method, the basic program for the form-finding of the complex cable net is compiled and finally used in this project with good results; The bearing capacity and deformation of key joints are checked by three-dimensional finite element analysis and anti-slip test. The above analysis results show that the structural selection of the single-layer cable net of this project is basically reasonable, and the design results meet the requirements of the current national specifications.
2023, 38(10): 49-58.
doi: 10.13206/j.gjgS23083102
Abstract:
Modular building, as a highly prefabricated building, has the characteristics of standardization, integration and industrialization, and has been rapidly popularized and applied in hotel, mobile cabin hospital and dormitory and so on. Compared with conventional buildings, modular buildings differ greatly in load transfer path, design method, construction mode and structural system. Based on the structural design of modular buildings, the design strategy of modular buildings and the key ideas of industrial application are expounded from the aspects of modular units, structural system, structural design, characteristics and application of modular buildings. Among them, the connection between internal components of module units, the connection between adjacent modules, and the connection between module units and lateral force resistant systems are the keys to the design of modular building structures. In order to promote the industrialization development of modular building, the vertical bearing system and the lateral force system are separated, so that the vertical bearing component is independent of the number of structural layers, making the stacked box structure easy to achieve the standardization of modular products.
Modular building, as a highly prefabricated building, has the characteristics of standardization, integration and industrialization, and has been rapidly popularized and applied in hotel, mobile cabin hospital and dormitory and so on. Compared with conventional buildings, modular buildings differ greatly in load transfer path, design method, construction mode and structural system. Based on the structural design of modular buildings, the design strategy of modular buildings and the key ideas of industrial application are expounded from the aspects of modular units, structural system, structural design, characteristics and application of modular buildings. Among them, the connection between internal components of module units, the connection between adjacent modules, and the connection between module units and lateral force resistant systems are the keys to the design of modular building structures. In order to promote the industrialization development of modular building, the vertical bearing system and the lateral force system are separated, so that the vertical bearing component is independent of the number of structural layers, making the stacked box structure easy to achieve the standardization of modular products.
2023, 38(10): 59-61.
doi: 10.13206/j.gjgS23022020
Abstract:
A brief review is given for the strength reduction factors of axially loaded members in Chinese standard for design of steel structures and the European counterpart. The reason for selecting a higher curve for columns with higher strength steel is given. To avoid abrupt change of column curve selection, a proposal is presented in which the imperfection factor includes the yielding strength corrector. The modified formulas for the column strength reduction factor can provide a continuous variation for steel with varied yielding strength. Comparison with the current code specifications is presented to show the rationality of the modification.
A brief review is given for the strength reduction factors of axially loaded members in Chinese standard for design of steel structures and the European counterpart. The reason for selecting a higher curve for columns with higher strength steel is given. To avoid abrupt change of column curve selection, a proposal is presented in which the imperfection factor includes the yielding strength corrector. The modified formulas for the column strength reduction factor can provide a continuous variation for steel with varied yielding strength. Comparison with the current code specifications is presented to show the rationality of the modification.
