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Steel Construction Published the List of Highly Influential Articles of 2020
2023 Vol. 38, No. 7
Display Method:
2023, 38(7): 1-11.
doi: 10.13206/j.gjgS23011002
Abstract
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Abstract:
The Glued-laminated timber-concrete simply-supported composite beam combines the structural mechanical properties of both glued wood and concrete. The wood beam forms a whole with the concrete slab through shear connectors, thus achieving a common working effect, and is widely used in multi-story buildings as well as in wood-frame buildings. Secondly, wood structure is in line with the development concept of green building, and the development of wood structure building can reduce the impact of the construction industry on the environment, which is of great importance.To investigate the effects of load form and peg arrangement on the slip, deflection and internal forces of Glued-laminated timber-concrete simply-supported composite beam, the modeling analysis was mainly performed using Ansys software and compared with the pegs in a uniform case arrangement to verify the correctness of the model. The basic assumption is that glulam and concrete are ideal linear elastic materials and that cracking of concrete is not considered. Based on this, this paper discusses the effects of the form of loading and the way the pegs are arranged on slip, deflection and internal forces. The modeling methods are as follow: for concrete C30, solid 65 units were used for modeling, wood was modeled with solid 45 units, while pegs were modeled and analyzed with conbine 39, and the constitutive model of pegs was modeled with the SST+S type joint fitted in Lukaszewska E. And parametric analysis is performed, and the slip, deflection and internal force of the combined beam were output. And compare the analysis with the theoretical values of the glued laminated wood-concrete composite beam.The results show that although wood is an orthotropic anisotropic material, it is possible to derive the equation for the Glued-laminated timber-concrete simply-supported composite beam by taking the modulus of elasticity in the same direction as the force according to the knowledge of mechanics of materials, and by using the theoretical equation for steel-composite combination beams. And its slip distribution law is consistent with the distribution law of steel-concrete combination beam, showing the distribution law of large at the end of the beam and small in the middle. Its effective stiffness can be calculated by using the "γ" in Eurocode EN 1995-1-1, and the error is very small. In conclusion, it is possible to derive the equation of glulam-concrete composite beam slip theory by the idea of steel-concrete composite beam slip theory, and the error is about 7%. Under the condition that the area of shear diagram is equal in size, the slip and deflection of the composite beam under symmetrical concentrated load are the largest, which should be avoided as much as possible in the project. Under most conditions, the pins should be arranged in reasonable segments according to the slip diagram, which can effectively reduce the slip and deflection of the composite beam. The Ansys finite element software can correctly simulate the Glued-laminated timber-concrete simply-supported composite beam with high accuracy, which provides methods and ideas for considering materials with orthotropic anisotropy.
The Glued-laminated timber-concrete simply-supported composite beam combines the structural mechanical properties of both glued wood and concrete. The wood beam forms a whole with the concrete slab through shear connectors, thus achieving a common working effect, and is widely used in multi-story buildings as well as in wood-frame buildings. Secondly, wood structure is in line with the development concept of green building, and the development of wood structure building can reduce the impact of the construction industry on the environment, which is of great importance.To investigate the effects of load form and peg arrangement on the slip, deflection and internal forces of Glued-laminated timber-concrete simply-supported composite beam, the modeling analysis was mainly performed using Ansys software and compared with the pegs in a uniform case arrangement to verify the correctness of the model. The basic assumption is that glulam and concrete are ideal linear elastic materials and that cracking of concrete is not considered. Based on this, this paper discusses the effects of the form of loading and the way the pegs are arranged on slip, deflection and internal forces. The modeling methods are as follow: for concrete C30, solid 65 units were used for modeling, wood was modeled with solid 45 units, while pegs were modeled and analyzed with conbine 39, and the constitutive model of pegs was modeled with the SST+S type joint fitted in Lukaszewska E. And parametric analysis is performed, and the slip, deflection and internal force of the combined beam were output. And compare the analysis with the theoretical values of the glued laminated wood-concrete composite beam.The results show that although wood is an orthotropic anisotropic material, it is possible to derive the equation for the Glued-laminated timber-concrete simply-supported composite beam by taking the modulus of elasticity in the same direction as the force according to the knowledge of mechanics of materials, and by using the theoretical equation for steel-composite combination beams. And its slip distribution law is consistent with the distribution law of steel-concrete combination beam, showing the distribution law of large at the end of the beam and small in the middle. Its effective stiffness can be calculated by using the "γ" in Eurocode EN 1995-1-1, and the error is very small. In conclusion, it is possible to derive the equation of glulam-concrete composite beam slip theory by the idea of steel-concrete composite beam slip theory, and the error is about 7%. Under the condition that the area of shear diagram is equal in size, the slip and deflection of the composite beam under symmetrical concentrated load are the largest, which should be avoided as much as possible in the project. Under most conditions, the pins should be arranged in reasonable segments according to the slip diagram, which can effectively reduce the slip and deflection of the composite beam. The Ansys finite element software can correctly simulate the Glued-laminated timber-concrete simply-supported composite beam with high accuracy, which provides methods and ideas for considering materials with orthotropic anisotropy.
2023, 38(7): 12-21.
doi: 10.13206/j.gjgS23030801
Abstract:
Concrete-filled steel tubular(CFST) members and various new-typed composite members derived from them have excellent mechanical properties and construction properties and are widely used in bridges and buildings. Encasing the CFRP profile into CFST members improves the bearing capacity of CFST members and reduces the section size, which has a great application prospect in bridges and high-rise buildings. Collisions between vehicles and bridge structures or buildings are frequent, and the destruction of buildings and bridges will have catastrophic consequences for human life and infrastructure systems. So it is particularly inportant to study the impact resistance performance of such components.However, the current design code generally adopts the equivalent static analysis method for the impact design of such members, which ignores the real influence process. Therefore, the finite element analysis(FEA) software ABAQUS was used to reveal the dynamic response of the concrete-filled circular steel tubular columns stiffened with encased with I-section CFRP profile(CFCST-CFRP) under lateral impact. Firstly, a CFCST-CFRP model coupled with axial force and impact was established, and its accuracy was verified based on the existing test data. Then, based on the impact force, displacement, stress and strain obtained by the verified FEA model, the failure mechanism of the CFCST-CFRP column under lateral impact was revealed. On this basis, the effects of CFRP profile configuration rate, impact velocity, axial compression ratio, slenderness ratio, steel ratio and impact direction on the impact resistance of CFCST-CFRP columns were explored. Finally, the energy dissipation mechanism of the CFCST-CFRP column under the coupling of axial force and impact was also explored. The results show that compared with ordinary CFST columns, the lateral impact resistance of CFCST-CFRP columns is significantly improved, and to give full play to the configuration rate of I-shaped CFRP profiles, it is recommended that the I-shaped CFRP profiles configuration rate should be between 6.2% and 7.4%. By analyzing the influence of the axial compression ratio, it is found that when the axial compression ratio is lower than 0.5, the axial force strengthens the lateral impact resistance of CFCST-CFRP columns. While the axial pressure ratio exceeds 0.5, the axial force weakens the lateral impact resistance of CFCST-CFRP columns. Under the same impact velocity, the impact resistance of CFCST-CFRP columns in the strong axial direction is better than that of the weak shaft impact direction, and when the impact velocity is large, it has the greater the influence on the deformation of the CFCST-CFRP column under impact load. The plastic energy dissipation of the steel tube is the main energy consumption mode of the CFCST-CFRP column. Although the energy dissipated by the CFRP profile accounts for a small proportion of total impact energy, it improves the deformation resistance of the CFCST-CFRP column.
Concrete-filled steel tubular(CFST) members and various new-typed composite members derived from them have excellent mechanical properties and construction properties and are widely used in bridges and buildings. Encasing the CFRP profile into CFST members improves the bearing capacity of CFST members and reduces the section size, which has a great application prospect in bridges and high-rise buildings. Collisions between vehicles and bridge structures or buildings are frequent, and the destruction of buildings and bridges will have catastrophic consequences for human life and infrastructure systems. So it is particularly inportant to study the impact resistance performance of such components.However, the current design code generally adopts the equivalent static analysis method for the impact design of such members, which ignores the real influence process. Therefore, the finite element analysis(FEA) software ABAQUS was used to reveal the dynamic response of the concrete-filled circular steel tubular columns stiffened with encased with I-section CFRP profile(CFCST-CFRP) under lateral impact. Firstly, a CFCST-CFRP model coupled with axial force and impact was established, and its accuracy was verified based on the existing test data. Then, based on the impact force, displacement, stress and strain obtained by the verified FEA model, the failure mechanism of the CFCST-CFRP column under lateral impact was revealed. On this basis, the effects of CFRP profile configuration rate, impact velocity, axial compression ratio, slenderness ratio, steel ratio and impact direction on the impact resistance of CFCST-CFRP columns were explored. Finally, the energy dissipation mechanism of the CFCST-CFRP column under the coupling of axial force and impact was also explored. The results show that compared with ordinary CFST columns, the lateral impact resistance of CFCST-CFRP columns is significantly improved, and to give full play to the configuration rate of I-shaped CFRP profiles, it is recommended that the I-shaped CFRP profiles configuration rate should be between 6.2% and 7.4%. By analyzing the influence of the axial compression ratio, it is found that when the axial compression ratio is lower than 0.5, the axial force strengthens the lateral impact resistance of CFCST-CFRP columns. While the axial pressure ratio exceeds 0.5, the axial force weakens the lateral impact resistance of CFCST-CFRP columns. Under the same impact velocity, the impact resistance of CFCST-CFRP columns in the strong axial direction is better than that of the weak shaft impact direction, and when the impact velocity is large, it has the greater the influence on the deformation of the CFCST-CFRP column under impact load. The plastic energy dissipation of the steel tube is the main energy consumption mode of the CFCST-CFRP column. Although the energy dissipated by the CFRP profile accounts for a small proportion of total impact energy, it improves the deformation resistance of the CFCST-CFRP column.
2023, 38(7): 22-28.
doi: 10.13206/j.gjgS22082202
Abstract:
Transmission towers are a class of highly flexible wind-sensitive structures, especially for transmission lines established in mountainous areas, where the towers are located in locations with large topographic and geomorphic variability, often with large height differences between towers, resulting in complex structural response of the tower-line system under wind loads. A typical transmission line section with large height difference in the coastal mountains of Wenzhou is used as the research object. Ansys software is used to establish a finite element model of two towers and three lines, and the dynamic characteristics of bare towers and tower line system are studied. The wind vibration response of bare towers and tower line system under 0° and 90° wind angle is analyzed, and the wind resistance of towers with different wind angles under design wind speed is evaluated. By analyzing the wind vibration response characteristics of the transmission tower at the top of the mountain and the internal force of the main material of the tower, the stress response law of the main material of the transmission tower with large height difference in mountainous areas is obtained, and the influence characteristics of the terrain height difference on the stress of the main material of the tower are mastered. The study shows that, in the case of constant horizontal gear distance, the greater the height difference between the two towers, the main material stress in the high tower shows a rapid increase trend, and the risk of wind collapse and damage of the tower located in the top of the mountain tower than that of the valley tower.
Transmission towers are a class of highly flexible wind-sensitive structures, especially for transmission lines established in mountainous areas, where the towers are located in locations with large topographic and geomorphic variability, often with large height differences between towers, resulting in complex structural response of the tower-line system under wind loads. A typical transmission line section with large height difference in the coastal mountains of Wenzhou is used as the research object. Ansys software is used to establish a finite element model of two towers and three lines, and the dynamic characteristics of bare towers and tower line system are studied. The wind vibration response of bare towers and tower line system under 0° and 90° wind angle is analyzed, and the wind resistance of towers with different wind angles under design wind speed is evaluated. By analyzing the wind vibration response characteristics of the transmission tower at the top of the mountain and the internal force of the main material of the tower, the stress response law of the main material of the transmission tower with large height difference in mountainous areas is obtained, and the influence characteristics of the terrain height difference on the stress of the main material of the tower are mastered. The study shows that, in the case of constant horizontal gear distance, the greater the height difference between the two towers, the main material stress in the high tower shows a rapid increase trend, and the risk of wind collapse and damage of the tower located in the top of the mountain tower than that of the valley tower.
2023, 38(7): 29-35.
doi: 10.13206/j.gjgS23020801
Abstract:
This paper reported a study on a new-type of the rigid connection between concrete-filled walls and steel beam, in which an end-plate of the same width as the wall thickness is welded on the edge of the CFT-wall, plus 4 side-plates welded onto the faces of the CFT-walls and the end-plate. Steel beams are welded to the end-plate using groove welds for the flange and fillet weld and high-strength bolts for the web. Plate plastic mechanism analysis method is carried out to determine the required thickness of the end-plate under the plastic moment of steel beam. Two cases are considered for the end plate, one is when the end plate has enough extended height, the other is the extended height equal to the slab thickness. The effect of the plastic moment of the side-plates has been considered in the proposed formulas. An extra joint factor 1.2 is introduced to include the effect of non-uniform distribution of longitudinal stress along the width of the beam flange to meet the demand of the seismic design demand of weak-beam-strong-connection. Finally shear strength check of the panel zone in the CFT-wall is introduced for the CFT-wall-steel beam connection.
This paper reported a study on a new-type of the rigid connection between concrete-filled walls and steel beam, in which an end-plate of the same width as the wall thickness is welded on the edge of the CFT-wall, plus 4 side-plates welded onto the faces of the CFT-walls and the end-plate. Steel beams are welded to the end-plate using groove welds for the flange and fillet weld and high-strength bolts for the web. Plate plastic mechanism analysis method is carried out to determine the required thickness of the end-plate under the plastic moment of steel beam. Two cases are considered for the end plate, one is when the end plate has enough extended height, the other is the extended height equal to the slab thickness. The effect of the plastic moment of the side-plates has been considered in the proposed formulas. An extra joint factor 1.2 is introduced to include the effect of non-uniform distribution of longitudinal stress along the width of the beam flange to meet the demand of the seismic design demand of weak-beam-strong-connection. Finally shear strength check of the panel zone in the CFT-wall is introduced for the CFT-wall-steel beam connection.
2023, 38(7): 36-41.
doi: 10.13206/j.gjgS23030802
Abstract:
Buckling of T-Sections under compression is studied analytically considering the interaction between flange and web. Formulas for the critical stress of the cross-section are presented. Extending the classification philosophy of steel plates to steel cross-sections, the paper obtained the interaction curves between the limiting values of the width-to-thickness ratios of flanges and webs for 4 classes(S1, S2, S3, S4) of the T-section. Based on the interaction curves, it is revealed that the classifications are composed of two regions: one is the traditional, in which flange and web are classified independently; the other is the extended region for which the width-to-thickness ratio of the web is relaxed and correspondingly the flange's width-to-thickness ratio is more stringent to reflect the weakening effect to the flange itself due to providing restraint to the web. For 4 classes of T-section, the limiting values are presented for possible references of codification.
Buckling of T-Sections under compression is studied analytically considering the interaction between flange and web. Formulas for the critical stress of the cross-section are presented. Extending the classification philosophy of steel plates to steel cross-sections, the paper obtained the interaction curves between the limiting values of the width-to-thickness ratios of flanges and webs for 4 classes(S1, S2, S3, S4) of the T-section. Based on the interaction curves, it is revealed that the classifications are composed of two regions: one is the traditional, in which flange and web are classified independently; the other is the extended region for which the width-to-thickness ratio of the web is relaxed and correspondingly the flange's width-to-thickness ratio is more stringent to reflect the weakening effect to the flange itself due to providing restraint to the web. For 4 classes of T-section, the limiting values are presented for possible references of codification.
2023, 38(7): 42-44.
doi: 10.13206/j.gjgS23041022
Abstract:
A brief review is given for the notional load approach, and clauses in the codes GB 50017, Eurocode 3 and AISC 360 are introduced. A new understanding is proposed for the total story number in the current code formulae, which is reinterpreted as the story number above the story at which the notional load exerts. Such a new explanation avoids the logical defect of the traditional notional load approach. A new equation is proposed for the notional load computation.
A brief review is given for the notional load approach, and clauses in the codes GB 50017, Eurocode 3 and AISC 360 are introduced. A new understanding is proposed for the total story number in the current code formulae, which is reinterpreted as the story number above the story at which the notional load exerts. Such a new explanation avoids the logical defect of the traditional notional load approach. A new equation is proposed for the notional load computation.
