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Steel Construction Published the List of Highly Influential Articles of 2020
2024 Vol. 39, No. 2
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2024, 39(2): 1-19.
doi: 10.3724/j.gjgS23080101
Abstract
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Abstract:
Due to the advantages such as lightweight, high strength, weather resistance and convenient processing and transportation, coated fabrics are widely applicated in various domains, including public buildings, emergency rescue, aerospace, industry, and the military. In recent years, to precisely analyze coated fabrics and drive their applications across multiple fields, the mechanical properties have become a central focus. An in-depth analysis of relevant literature spanning over two decades from both domestic and international sources was conducted utilizing CiteSpace. It employs visual knowledge mapping to elucidate the evolution of research hotspots in membrane structure and systematically examines research advancements in testing methods, mechanical properties and macro-micro constitutive models. A review reveals that the early stages were primarily centered around structural form-finding and static analysis. However, with the wide application of membrane structure in different fields in China, the research has been expanded to various fields such as material non-linear constitutive behavior, strength criteria and structural risk assessment. 1) The tensile performance of coated fabrics is influenced by various factors, including microstructure, base fabric weaving process, coating technique and fiber type, resulting in distinct anisotropic characteristics. The tensile strength exhibits two distinct variations, resembling a "U" shape and a "W" shape, with increasing off-axis angles. 2) Biaxial shear testing methods have been widely adopted to ensure a uniform distribution of shear stress in the core region of specimens and are currently prevalent in assessing shear performance of coated fabrics. 3) The tear strength of coated fabrics is significantly influenced by the testing method, with current research predominantly focused on tear performance of coated fabrics. The impact mechanism of initial defects on the static and dynamic performance of membrane structures requires further clarification. 4) Presently, research on membrane structure connections primarily emphasizes in-plane tensile performance of bonded connections between membrane panels, overlooking the potential of delamination failures under out-of-plane loads. 5) Constitutive models for coated fabrics are categorized into micromechanical models and macroscopic phenomenological models. Existing macroscopic models have largely succeeded in describing the nonlinear, non-elastic and viscoelastic mechanical characteristics of coated fabrics, while micro-mechanical models tend to focus more on predicting tensile stiffness, with relatively limited research pertaining to predicting tensile strength. After years of effort, the research on coated fabrics has made substantial progress. However, several issues still require further investigation. 1) The current classification of coated fabrics is monotonous and fails to consider differences in intended use and characteristics. 2) Membrane structure damage primarily involves tearing, yet design specifications have not been adequately addressed. 3) In-plane tensile testing is difficult to accurately reflect the real stress states, mechanical properties and failure modes in the heat-sealed regions of coated fabrics. The impact mechanisms of heat-sealing welding processes on the performance of joint of coated fabrics require further investigation. 4) Currently, there is a paucity of research on the fatigue performance of coated fabrics and the connection points, and the fatigue damage mechanisms have yet to be clearly elucidated.
Due to the advantages such as lightweight, high strength, weather resistance and convenient processing and transportation, coated fabrics are widely applicated in various domains, including public buildings, emergency rescue, aerospace, industry, and the military. In recent years, to precisely analyze coated fabrics and drive their applications across multiple fields, the mechanical properties have become a central focus. An in-depth analysis of relevant literature spanning over two decades from both domestic and international sources was conducted utilizing CiteSpace. It employs visual knowledge mapping to elucidate the evolution of research hotspots in membrane structure and systematically examines research advancements in testing methods, mechanical properties and macro-micro constitutive models. A review reveals that the early stages were primarily centered around structural form-finding and static analysis. However, with the wide application of membrane structure in different fields in China, the research has been expanded to various fields such as material non-linear constitutive behavior, strength criteria and structural risk assessment. 1) The tensile performance of coated fabrics is influenced by various factors, including microstructure, base fabric weaving process, coating technique and fiber type, resulting in distinct anisotropic characteristics. The tensile strength exhibits two distinct variations, resembling a "U" shape and a "W" shape, with increasing off-axis angles. 2) Biaxial shear testing methods have been widely adopted to ensure a uniform distribution of shear stress in the core region of specimens and are currently prevalent in assessing shear performance of coated fabrics. 3) The tear strength of coated fabrics is significantly influenced by the testing method, with current research predominantly focused on tear performance of coated fabrics. The impact mechanism of initial defects on the static and dynamic performance of membrane structures requires further clarification. 4) Presently, research on membrane structure connections primarily emphasizes in-plane tensile performance of bonded connections between membrane panels, overlooking the potential of delamination failures under out-of-plane loads. 5) Constitutive models for coated fabrics are categorized into micromechanical models and macroscopic phenomenological models. Existing macroscopic models have largely succeeded in describing the nonlinear, non-elastic and viscoelastic mechanical characteristics of coated fabrics, while micro-mechanical models tend to focus more on predicting tensile stiffness, with relatively limited research pertaining to predicting tensile strength. After years of effort, the research on coated fabrics has made substantial progress. However, several issues still require further investigation. 1) The current classification of coated fabrics is monotonous and fails to consider differences in intended use and characteristics. 2) Membrane structure damage primarily involves tearing, yet design specifications have not been adequately addressed. 3) In-plane tensile testing is difficult to accurately reflect the real stress states, mechanical properties and failure modes in the heat-sealed regions of coated fabrics. The impact mechanisms of heat-sealing welding processes on the performance of joint of coated fabrics require further investigation. 4) Currently, there is a paucity of research on the fatigue performance of coated fabrics and the connection points, and the fatigue damage mechanisms have yet to be clearly elucidated.
2024, 39(2): 20-29.
doi: 10.3724/j.gjgS23072902
Abstract:
Air-inflated rib membrane structure is a kind of structure or component using high-pressure air-inflated ribs as support system, which can create space by connecting multiple air-inflated ribs. It has the advantages of lightweight and portable, fast transportation, low energy consumption, safety and reliability. In order to create the structure with large span and strong load-bearing capacity, the scholars at home and abroad have conducted thorough researches on this issue, and the air-inflated rib membrane structures have been widely used and developed, which have become symbolic buildings in many cities at home and abroad. Firstly, the structural form of the air-inflated rib membrane structure, and the function and design requirements of internal pressure were summarized in this paper. The internal pressure in engineering applications was described briefly, the methods of monitoring the performance and the studies of failure performance were outlined. Then, a summary of examples of the air-inflated rib membrane structure used in engineering projects was concluded. This structural form has been widely used in exhibition halls, sports venues, laboratories, aircraft hangars, warehouses and other practical engineering projects. In large-span air-inflated structures, the trip-cage type air-inflated rib membrane structure provides an effective method for connecting multiple air-ribs. The strip connection type can greatly improve the bearing capacity of a single air-inflated rib and the cooperative working ability between air-inflated ribs. The structural characteristics and engineering applications of large aircraft hangars built by BUILDAIR Company using the strip-cage type air-inflated rib membrane structure were emphatically introduced. Finally, the relationship between the diameter of the air-inflated rib and the span of the structure in engineering applications was investigated. The result shows that the ratio between the diameter of the air-inflated rib and the span of the structure is about 1/10 in most of the strip-cage type air-inflated rib membrane structure engineering cases. However, the selection of the diameter needs to be determined by design analysis according to the actual engineering conditions.
Air-inflated rib membrane structure is a kind of structure or component using high-pressure air-inflated ribs as support system, which can create space by connecting multiple air-inflated ribs. It has the advantages of lightweight and portable, fast transportation, low energy consumption, safety and reliability. In order to create the structure with large span and strong load-bearing capacity, the scholars at home and abroad have conducted thorough researches on this issue, and the air-inflated rib membrane structures have been widely used and developed, which have become symbolic buildings in many cities at home and abroad. Firstly, the structural form of the air-inflated rib membrane structure, and the function and design requirements of internal pressure were summarized in this paper. The internal pressure in engineering applications was described briefly, the methods of monitoring the performance and the studies of failure performance were outlined. Then, a summary of examples of the air-inflated rib membrane structure used in engineering projects was concluded. This structural form has been widely used in exhibition halls, sports venues, laboratories, aircraft hangars, warehouses and other practical engineering projects. In large-span air-inflated structures, the trip-cage type air-inflated rib membrane structure provides an effective method for connecting multiple air-ribs. The strip connection type can greatly improve the bearing capacity of a single air-inflated rib and the cooperative working ability between air-inflated ribs. The structural characteristics and engineering applications of large aircraft hangars built by BUILDAIR Company using the strip-cage type air-inflated rib membrane structure were emphatically introduced. Finally, the relationship between the diameter of the air-inflated rib and the span of the structure in engineering applications was investigated. The result shows that the ratio between the diameter of the air-inflated rib and the span of the structure is about 1/10 in most of the strip-cage type air-inflated rib membrane structure engineering cases. However, the selection of the diameter needs to be determined by design analysis according to the actual engineering conditions.
2024, 39(2): 30-42.
doi: 10.3724/j.gjgS23051902
Abstract:
STFE membrane is a new type of high-transparency building membrane material. This material combines the high tensile strength and tear strength of coated fabric membrane materials with the high transparency of polymer membrane materials, making it suitable for use in tension membrane structures that require a transparent effect. As a new imported membrane material, in order to be used in domestic building structure design, its mechanical properties need to be tested according to domestic standards. According to the “Standard for Inspection of Membrane Structures” (DG/TJ 08-2019-2019), six mechanical properties of STFE membrane were tested: tensile strength and elongation at break, tear strength, elastic modulus and Poisson's ratio, shear modulus, creep elongation, and connection strength. The test results showed that the tensile strength of STFE membrane in the warp direction was 4 241 N/(5 cm), and in the weft direction was 4 335 N/(5 cm); the tear strength in the warp direction was 809 N, and in the weft direction was 873 N; the elastic modulus in the warp direction was 1 512 kN/m, and in the weft direction was 2 352 kN/m; the shear modulus was 30.5 kN/m; the creep elongation in the warp direction was 0.85%, and in the weft direction was 0.73%; and the connection strength between membrane pieces at room temperature can reach 100% of the main material. To clarify the application scenarios of STFE membrane materials, this article introduces the current applications of this material in some new building and building renovation projects both domestically and internationally, including metro pedestrian road cover at Istanbul International Airport, temporary venues for Paris 2024 Olympic Games at Grand Palais, canopy walkway at CrossBrent station in London, lounge rooftop renovation at Royal Orthopaedic Hospital in London(Horatio's garden), landscape pavilion at Melbourne Mpavillion, and shading pavilion at Foshan Boai Lake Park. In tensile membrane structures, welding connections are important components. Referring to the STFE membrane material technical guide, this article introduces various forms of high-frequency welding connections in such structures, including membrane-to-membrane connections, membrane-to-edge cable connections, membrane-to- coated fabric membrane connections, and multi-layer membrane clamping plate mechanical connections. Through the above measurements of the mechanical parameters of STFE membrane material and a brief introduction to its applications and connection methods in structures, certain references are provided for the promotion and application of this type of membrane material in China.
STFE membrane is a new type of high-transparency building membrane material. This material combines the high tensile strength and tear strength of coated fabric membrane materials with the high transparency of polymer membrane materials, making it suitable for use in tension membrane structures that require a transparent effect. As a new imported membrane material, in order to be used in domestic building structure design, its mechanical properties need to be tested according to domestic standards. According to the “Standard for Inspection of Membrane Structures” (DG/TJ 08-2019-2019), six mechanical properties of STFE membrane were tested: tensile strength and elongation at break, tear strength, elastic modulus and Poisson's ratio, shear modulus, creep elongation, and connection strength. The test results showed that the tensile strength of STFE membrane in the warp direction was 4 241 N/(5 cm), and in the weft direction was 4 335 N/(5 cm); the tear strength in the warp direction was 809 N, and in the weft direction was 873 N; the elastic modulus in the warp direction was 1 512 kN/m, and in the weft direction was 2 352 kN/m; the shear modulus was 30.5 kN/m; the creep elongation in the warp direction was 0.85%, and in the weft direction was 0.73%; and the connection strength between membrane pieces at room temperature can reach 100% of the main material. To clarify the application scenarios of STFE membrane materials, this article introduces the current applications of this material in some new building and building renovation projects both domestically and internationally, including metro pedestrian road cover at Istanbul International Airport, temporary venues for Paris 2024 Olympic Games at Grand Palais, canopy walkway at CrossBrent station in London, lounge rooftop renovation at Royal Orthopaedic Hospital in London(Horatio's garden), landscape pavilion at Melbourne Mpavillion, and shading pavilion at Foshan Boai Lake Park. In tensile membrane structures, welding connections are important components. Referring to the STFE membrane material technical guide, this article introduces various forms of high-frequency welding connections in such structures, including membrane-to-membrane connections, membrane-to-edge cable connections, membrane-to- coated fabric membrane connections, and multi-layer membrane clamping plate mechanical connections. Through the above measurements of the mechanical parameters of STFE membrane material and a brief introduction to its applications and connection methods in structures, certain references are provided for the promotion and application of this type of membrane material in China.
2024, 39(2): 43-49.
doi: 10.3724/j.gjgS23051801
Abstract:
To meet the requirements of architectural design, colored ETFE foils have been developed and applied to modern large public buildings. However, as a new material, research on the properties of colored ETFE foils is relatively limited, especially the typical photothermal properties of ETFE foils. Starting from practical engineering applications, nine kinds of colored ETFE foils and one kind of colorless transparent ETFE foil, which were used in the Chengdu Agricultural Expo Park as representative samples, were selected for experimental testing of their light transmittance and thermal properties. Firstly, a UV visible near-infrared spectrophotometer was used to measure the transmittance and reflectance of the test foil in the solar radiation band. By comparing the trend and fluctuation of the solar radiation curves between colored ETFE foils and colorless transparent ETFE foil, the changes in the light transmittance and thermal radiation property of colored ETFE foils and colorless transparent ETFE foil in the solar radiation band were analyze. The visible light transmittance and solar radiation coefficient of the test foil were calculated and obtained. The thermal conductivity property of the test foil was measured using laser scattering method, and the thermal conductivity coefficient and thermal resistance of the test foil at room temperature were calculated. The changes in photothermal property parameters of ETFE foils with different colors are summarized and compared them with colorless transparent ETFE foil. The results show that: 1) in the ultraviolet region, both the transmittance and reflectance of colored ETFE foils are at a low level (not exceeding 30% in total), and colored ETFE foils have strong absorption capacity for ultraviolet rays. In practical use, attention should be paid to the aging problem of colored ETFE foils. 2) The visible light transmittance and solar radiation transmission coefficient of colored ETFE foil are lower than those of colorless transparent ETFE foil, and the thermal conductivity is slightly lower than that of colorless transparent ETFE foil. The solar radiation absorption coefficient and thermal resistance of the colored ETFE foil at the same thickness are both higher than those of colorless transparent ETFE foil. 3) The main factor affecting the visible light transmittance and solar radiation coefficient of colored ETFE foils is the depth of the foil color. The lighter the foil color, the greater the visible light transmittance, the greater the solar radiation transmission coefficient, and the smaller the absorption coefficient. As the color of the foil deepens, the absorption ability of the foil to sunlight gradually increases, and the transmission and reflection coefficients are relatively low. 4) The main factor affecting the thermal resistance of colored ETFE foils is the foil thickness. Under the same thickness, the thermal resistance of colored ETFE foils is 7%-14% higher than that of colorless transparent ETFE foil. The research results indicate that using colored ETFE foil as a building enclosure structure can increase the reflection and absorption of solar radiation by the enclosure structure, and to some extent block heat conduction, reducing the problem of excessive indoor lighting and summer overheating.
To meet the requirements of architectural design, colored ETFE foils have been developed and applied to modern large public buildings. However, as a new material, research on the properties of colored ETFE foils is relatively limited, especially the typical photothermal properties of ETFE foils. Starting from practical engineering applications, nine kinds of colored ETFE foils and one kind of colorless transparent ETFE foil, which were used in the Chengdu Agricultural Expo Park as representative samples, were selected for experimental testing of their light transmittance and thermal properties. Firstly, a UV visible near-infrared spectrophotometer was used to measure the transmittance and reflectance of the test foil in the solar radiation band. By comparing the trend and fluctuation of the solar radiation curves between colored ETFE foils and colorless transparent ETFE foil, the changes in the light transmittance and thermal radiation property of colored ETFE foils and colorless transparent ETFE foil in the solar radiation band were analyze. The visible light transmittance and solar radiation coefficient of the test foil were calculated and obtained. The thermal conductivity property of the test foil was measured using laser scattering method, and the thermal conductivity coefficient and thermal resistance of the test foil at room temperature were calculated. The changes in photothermal property parameters of ETFE foils with different colors are summarized and compared them with colorless transparent ETFE foil. The results show that: 1) in the ultraviolet region, both the transmittance and reflectance of colored ETFE foils are at a low level (not exceeding 30% in total), and colored ETFE foils have strong absorption capacity for ultraviolet rays. In practical use, attention should be paid to the aging problem of colored ETFE foils. 2) The visible light transmittance and solar radiation transmission coefficient of colored ETFE foil are lower than those of colorless transparent ETFE foil, and the thermal conductivity is slightly lower than that of colorless transparent ETFE foil. The solar radiation absorption coefficient and thermal resistance of the colored ETFE foil at the same thickness are both higher than those of colorless transparent ETFE foil. 3) The main factor affecting the visible light transmittance and solar radiation coefficient of colored ETFE foils is the depth of the foil color. The lighter the foil color, the greater the visible light transmittance, the greater the solar radiation transmission coefficient, and the smaller the absorption coefficient. As the color of the foil deepens, the absorption ability of the foil to sunlight gradually increases, and the transmission and reflection coefficients are relatively low. 4) The main factor affecting the thermal resistance of colored ETFE foils is the foil thickness. Under the same thickness, the thermal resistance of colored ETFE foils is 7%-14% higher than that of colorless transparent ETFE foil. The research results indicate that using colored ETFE foil as a building enclosure structure can increase the reflection and absorption of solar radiation by the enclosure structure, and to some extent block heat conduction, reducing the problem of excessive indoor lighting and summer overheating.
2024, 39(2): 50-57.
doi: 10.3724/j.gjgS23051802
Abstract:
Inflatable membrane structures are typical wind sensitive structures, and the membrane surface will undergo significant deformation under wind load. Wind resistance is an important factor restricting the development of membrane structures. In order to study the wind load characteristics of inflatable membrane structures with rectangular plane, six different rigid models were designed and manufactured. Three types of landforms, A, B, and C, were simulated using wedges, rough elements, and serrated baffles. The pressure tests of the rigid models with rectangular plane were carried out in the atmospheric boundary layer wind tunnel, and the effects of wind direction, rise-span ratio, length-width ratio and ground roughness on the mean wind pressure distribution were analyzed, and the wind coefficient of the structure was calculated at different wind directions. Based on wind load data obtained from wind tunnel tests, wind vibration response analysis was conducted on a prototype sized inflatable membrane structure with rectangular plane by the finite element software ABAQUS. The membrane surface was modeled using M3D4R elements, and the cable was modeled using T3D2 elements. The mean wind response characteristics of the structure under different wind directions were studied, and the displacement and stress distribution patterns of the membrane surface under wind load were summarized. The locations where the displacement and stress extremes occurred were determined. Finally, a partition scheme for wind load shape coefficient applicable to inflatable membrane structures with rectangular plane was proposed, and suggested values for different partitions were given. The results show that the mean wind pressure coefficient distribution of inflatable membrane structures with rectangular plane is greatly affected by the wind direction and the length-width ratio of the structure, but less affected by the ground roughness. As the length-width ratio decreases, the wind pressure in the upper suction area decreases. As the rise-span ratio increases, the positive wind pressure coefficient in the windward region increases, and the negative wind pressure in the upper suction region decreases. The wind force coefficient of inflatable membrane structures with rectangular plane is the highest at 0° wind attack angle. The inflatable membrane structure with rectangular plane has significant deformation on the windward surface and top at 0° and 45° wind attack angle, while the deformation on the windward surface is significant at 90° wind attack angle and the deformation on the top is relatively small. At 0° and 90° wind attack angle, the stress in the protruding parts connecting the two sides and the middle of the structure is relatively high. At 45° wind attack angle, there are obvious folds and stress concentration at the corner of the windward surface. The maximum displacement and stress are observed at 0° wind attack angle, while the minimum displacement and stress are observed at 90° wind attack angle. It is recommended to use 5 zones for the wind load shape coefficient of inflatable membrane structures with rectangular plane at 0° and 90° wind attack angle, and 7 zones at 45° wind attack angle. The zoning wind load shape coefficient at 0° and 90° wind attack angle is significantly affected by the rise-span ratio, while at 45° wind attack angle it is significantly affected by the length-width ratio.
Inflatable membrane structures are typical wind sensitive structures, and the membrane surface will undergo significant deformation under wind load. Wind resistance is an important factor restricting the development of membrane structures. In order to study the wind load characteristics of inflatable membrane structures with rectangular plane, six different rigid models were designed and manufactured. Three types of landforms, A, B, and C, were simulated using wedges, rough elements, and serrated baffles. The pressure tests of the rigid models with rectangular plane were carried out in the atmospheric boundary layer wind tunnel, and the effects of wind direction, rise-span ratio, length-width ratio and ground roughness on the mean wind pressure distribution were analyzed, and the wind coefficient of the structure was calculated at different wind directions. Based on wind load data obtained from wind tunnel tests, wind vibration response analysis was conducted on a prototype sized inflatable membrane structure with rectangular plane by the finite element software ABAQUS. The membrane surface was modeled using M3D4R elements, and the cable was modeled using T3D2 elements. The mean wind response characteristics of the structure under different wind directions were studied, and the displacement and stress distribution patterns of the membrane surface under wind load were summarized. The locations where the displacement and stress extremes occurred were determined. Finally, a partition scheme for wind load shape coefficient applicable to inflatable membrane structures with rectangular plane was proposed, and suggested values for different partitions were given. The results show that the mean wind pressure coefficient distribution of inflatable membrane structures with rectangular plane is greatly affected by the wind direction and the length-width ratio of the structure, but less affected by the ground roughness. As the length-width ratio decreases, the wind pressure in the upper suction area decreases. As the rise-span ratio increases, the positive wind pressure coefficient in the windward region increases, and the negative wind pressure in the upper suction region decreases. The wind force coefficient of inflatable membrane structures with rectangular plane is the highest at 0° wind attack angle. The inflatable membrane structure with rectangular plane has significant deformation on the windward surface and top at 0° and 45° wind attack angle, while the deformation on the windward surface is significant at 90° wind attack angle and the deformation on the top is relatively small. At 0° and 90° wind attack angle, the stress in the protruding parts connecting the two sides and the middle of the structure is relatively high. At 45° wind attack angle, there are obvious folds and stress concentration at the corner of the windward surface. The maximum displacement and stress are observed at 0° wind attack angle, while the minimum displacement and stress are observed at 90° wind attack angle. It is recommended to use 5 zones for the wind load shape coefficient of inflatable membrane structures with rectangular plane at 0° and 90° wind attack angle, and 7 zones at 45° wind attack angle. The zoning wind load shape coefficient at 0° and 90° wind attack angle is significantly affected by the rise-span ratio, while at 45° wind attack angle it is significantly affected by the length-width ratio.
2024, 39(2): 58-60.
doi: 10.3724/j.gjgS23031020
Abstract:
Seismic design has the characteristic of self-fulfillment. Seismic behavior of members depends on three aspects: capacity, ductility and plumpness of hysteretic curves. Method for seismic design to standard GB 50017-2017 is introduced. For system performance factors the required modifications incorporating effects of short period, MDOF, second order effect and damping are introduced. The control of ductility development mechanism and its control method are introduced. A new explanation is provided for the enlargement of seismic effect in the bottom stories, finally the design technique of second-order analysis used for seismic design is discussed.
Seismic design has the characteristic of self-fulfillment. Seismic behavior of members depends on three aspects: capacity, ductility and plumpness of hysteretic curves. Method for seismic design to standard GB 50017-2017 is introduced. For system performance factors the required modifications incorporating effects of short period, MDOF, second order effect and damping are introduced. The control of ductility development mechanism and its control method are introduced. A new explanation is provided for the enlargement of seismic effect in the bottom stories, finally the design technique of second-order analysis used for seismic design is discussed.
