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Steel Construction Published the List of Highly Influential Articles of 2020
2020 Vol. 35, No. 10
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2020, 35(10): 1-8.
doi: 10.13206/j.gjgS20060303
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Abstract:
The gymnasium and natatorium of Hangzhou Olympic Sports Center are the main stadiums of Hangzhou Asian Games in 2022. The roofs of gymnasium and natatorium are connected as a whole through the central hall. The steel roofs of the gymnasium and natatorium adopt the structure of double-layer latticed shell and the roof of the central hall is a single-layer latticed shell with heteromorphic surface.There is a single-layer cantilever lattice shell structure on the east and west sides of the gymnasium and natatorium. The natatorium and gymnasium roof can be divided into double-layer reticulated shell, single-layer reticulated shell, boundary truss, gate arch truss, etc.Steel roof members have various forms and complex joints, which are composed of bending-torsion L-shaped beam, bending-torsion box members of variable section and "drum" joints. The steel roof has the characteristics of complex shape and large span. Also the construction period of the project is tight, there are many specialties and high quality requirements
The key and difficult points of steel roof construction in various stages, such as deepening design, manufacturing, field installation and digital information management, were introduced.During the construction process, the construction environment of the whole structure was complex, the deepening processing of components and joints was difficult, and the installation configuration was difficult to control, there were many aerial operations and high welding quality requirements. The key construction techniques and methods in the construction stage of hyperbolic reticulated shell roof were emphatically expounded. The construction organization of "information organization and management, process interpenetration, time limit and land limitation" was adopted to solve the construction difficulties of various disciplines in large stadiums and gymnasiums. The double construction scheme of "large traveling tower crane block hoisting combined with local hydraulic integral lifting" solved the difficulties of tight construction period and high quality requirements of the project, and realized the key technology of large tonnage tower crane working on the floor and floor arc walking; the working method of "floor multi-point assembly and high-altitude local butt joint" solved the stress concentration of all welded structure and ensures the high quality and safety of the structure with low risk. The measurement, positioning and installation technology of special-shaped curved surface structure realized the installation accuracy of single-layer special-shaped curved surface roof composed of bending and torsion members. The data obtained from the simulation analysis of the whole process of structural installation, closure and unloading by the finite element analysis software provided sufficient scientific basis for the construction process control. Through the comparative analysis of the simulation theoretical data and the measured data, the feasibility of the construction technology was verified, which provided important reference value for the follow-up similar projects. Through the combination of theory and practice, the key construction technology described in this paper solved the technical problems of steel roof construction of gymnasium and natatorium of Hangzhou Olympic Sports Center. The results showed that the construction was safe and reliable; the quality could meet the requirements of specifications and design, and realized the idea of "green, intelligent, thrifty and civilized".
The gymnasium and natatorium of Hangzhou Olympic Sports Center are the main stadiums of Hangzhou Asian Games in 2022. The roofs of gymnasium and natatorium are connected as a whole through the central hall. The steel roofs of the gymnasium and natatorium adopt the structure of double-layer latticed shell and the roof of the central hall is a single-layer latticed shell with heteromorphic surface.There is a single-layer cantilever lattice shell structure on the east and west sides of the gymnasium and natatorium. The natatorium and gymnasium roof can be divided into double-layer reticulated shell, single-layer reticulated shell, boundary truss, gate arch truss, etc.Steel roof members have various forms and complex joints, which are composed of bending-torsion L-shaped beam, bending-torsion box members of variable section and "drum" joints. The steel roof has the characteristics of complex shape and large span. Also the construction period of the project is tight, there are many specialties and high quality requirements
The key and difficult points of steel roof construction in various stages, such as deepening design, manufacturing, field installation and digital information management, were introduced.During the construction process, the construction environment of the whole structure was complex, the deepening processing of components and joints was difficult, and the installation configuration was difficult to control, there were many aerial operations and high welding quality requirements. The key construction techniques and methods in the construction stage of hyperbolic reticulated shell roof were emphatically expounded. The construction organization of "information organization and management, process interpenetration, time limit and land limitation" was adopted to solve the construction difficulties of various disciplines in large stadiums and gymnasiums. The double construction scheme of "large traveling tower crane block hoisting combined with local hydraulic integral lifting" solved the difficulties of tight construction period and high quality requirements of the project, and realized the key technology of large tonnage tower crane working on the floor and floor arc walking; the working method of "floor multi-point assembly and high-altitude local butt joint" solved the stress concentration of all welded structure and ensures the high quality and safety of the structure with low risk. The measurement, positioning and installation technology of special-shaped curved surface structure realized the installation accuracy of single-layer special-shaped curved surface roof composed of bending and torsion members. The data obtained from the simulation analysis of the whole process of structural installation, closure and unloading by the finite element analysis software provided sufficient scientific basis for the construction process control. Through the comparative analysis of the simulation theoretical data and the measured data, the feasibility of the construction technology was verified, which provided important reference value for the follow-up similar projects. Through the combination of theory and practice, the key construction technology described in this paper solved the technical problems of steel roof construction of gymnasium and natatorium of Hangzhou Olympic Sports Center. The results showed that the construction was safe and reliable; the quality could meet the requirements of specifications and design, and realized the idea of "green, intelligent, thrifty and civilized".
2020, 35(10): 9-14.
doi: 10.13206/j.gjgS20060302
Abstract:
The steel roof project of the three Asian games stadiums of Hangzhou Olympic Sports Center was divided into three parts:natatorium roof, central hall roof and gymnasium roof. It was composed of single layer and double layer reticulated shell. Among them natatorium and gymnasium roof was also divided into double-layer reticulated shell, single-layer reticulated shell, junction truss and gate arch structure and so on. And the roof of the central hall was divided into a single-layer reticular shell and two bucket structure. The roof has large span and complex shape that its members were mainly box-type bending and torsion members. The construction plan that was large walking tower crane block lifting and local hydraulic integral lifting was adopted.
This paper first introduced the general idea of steel structure installation that steel structure divided into three areas and five construction areas, lifting area and lifting area for cross construction and finally for sectional unloading.Secondly, the whole process of steel structure installation including installation and unloading was simulated with MIDAS software. The stress and deformation analysis of the control conditions in each construction zone was emphatically analyzed, and compared with the stress and deformation in the designed state. The control points of vertical deformation were selected by selecting the chord of the middle span of the natatorium, gymnasium and central hall as the stress control unit, and 1/2 span and 1/4 span as the control points of vertical deformation. The changing of stress and deformation during construction was analyzed, its result showed that unloading step was key working condition of control. Finally, the paper introduced the analysis of lifting construction of the lifting area, the result showed that a member with high stress was near the lifting point in the large area, and the stress ratio decreased after and unloading, so as to meet the safety requirements of construction. The simulation results of the whole construction process verified the feasibility of the construction method, due to the large structural boundary stiffness of the natatorium, the central hall and the gymnasium, the construction process had little influence on each other that also verified the feasibility of the construction method of partition installation and partition unloading.
The steel roof project of the three Asian games stadiums of Hangzhou Olympic Sports Center was divided into three parts:natatorium roof, central hall roof and gymnasium roof. It was composed of single layer and double layer reticulated shell. Among them natatorium and gymnasium roof was also divided into double-layer reticulated shell, single-layer reticulated shell, junction truss and gate arch structure and so on. And the roof of the central hall was divided into a single-layer reticular shell and two bucket structure. The roof has large span and complex shape that its members were mainly box-type bending and torsion members. The construction plan that was large walking tower crane block lifting and local hydraulic integral lifting was adopted.
This paper first introduced the general idea of steel structure installation that steel structure divided into three areas and five construction areas, lifting area and lifting area for cross construction and finally for sectional unloading.Secondly, the whole process of steel structure installation including installation and unloading was simulated with MIDAS software. The stress and deformation analysis of the control conditions in each construction zone was emphatically analyzed, and compared with the stress and deformation in the designed state. The control points of vertical deformation were selected by selecting the chord of the middle span of the natatorium, gymnasium and central hall as the stress control unit, and 1/2 span and 1/4 span as the control points of vertical deformation. The changing of stress and deformation during construction was analyzed, its result showed that unloading step was key working condition of control. Finally, the paper introduced the analysis of lifting construction of the lifting area, the result showed that a member with high stress was near the lifting point in the large area, and the stress ratio decreased after and unloading, so as to meet the safety requirements of construction. The simulation results of the whole construction process verified the feasibility of the construction method, due to the large structural boundary stiffness of the natatorium, the central hall and the gymnasium, the construction process had little influence on each other that also verified the feasibility of the construction method of partition installation and partition unloading.
2020, 35(10): 15-21.
doi: 10.13206/j.gjgS20060304
Abstract:
Hangzhou Olympic Sports Center Comprehensive Training Center is one of the venues for the 19th Asian Games in Hangzhou 2022. The underground steel structure has the characteristics of component weight, special section shape and complex construction conditions. The outer cylinder of the main building on the ground adopts oblique steel tube grid column which is cross-braided with the ground at 56.3°.Large diameter, large number of grid column and heavy components make it difficult to locate on site. Especially, the structure and stress of oblique grid joint are complex, and there are many hidden welds and intersecting welds with small angle, which bring great difficulties to the processing welding and installation on site.
By closely cooperating with civil construction, optimizing the arrangement of civil steel reinforcement and reducing the interference between steel structure and civil steel reinforcement, and reasonably organizing the construction sequence, the influence of multi-specialty cross construction was solved. In the complex construction environment, the circular construction road that meet the construction requirements was opened. Scientific hoisting methods and stable temporary measures were used to ensure the safety of the structure in the construction process. Adopting digital measurement technology of "computer-aided electronic total station" to control the installation precision of components; in the process of deepening the design, through a large number of analysis tests and studies, the welding requirements of skew grid joints were innovatively optimized, and the feasibility of the optimized scheme was verified by finite element analysis. The finite element analysis for steel structure construction process was carried out, according to the results of the simulation analysis, the key parts and links to be monitored in the construction process of steel structure were determined; according to the stress and displacement of the cantilever parts during construction,the principle of priority to dismantle the most disadvantageous support was determined, and the cantilever support was removed by stages. The above method had been successfully applied in this project, which provided certain reference for similar steel structure engineering.
Hangzhou Olympic Sports Center Comprehensive Training Center is one of the venues for the 19th Asian Games in Hangzhou 2022. The underground steel structure has the characteristics of component weight, special section shape and complex construction conditions. The outer cylinder of the main building on the ground adopts oblique steel tube grid column which is cross-braided with the ground at 56.3°.Large diameter, large number of grid column and heavy components make it difficult to locate on site. Especially, the structure and stress of oblique grid joint are complex, and there are many hidden welds and intersecting welds with small angle, which bring great difficulties to the processing welding and installation on site.
By closely cooperating with civil construction, optimizing the arrangement of civil steel reinforcement and reducing the interference between steel structure and civil steel reinforcement, and reasonably organizing the construction sequence, the influence of multi-specialty cross construction was solved. In the complex construction environment, the circular construction road that meet the construction requirements was opened. Scientific hoisting methods and stable temporary measures were used to ensure the safety of the structure in the construction process. Adopting digital measurement technology of "computer-aided electronic total station" to control the installation precision of components; in the process of deepening the design, through a large number of analysis tests and studies, the welding requirements of skew grid joints were innovatively optimized, and the feasibility of the optimized scheme was verified by finite element analysis. The finite element analysis for steel structure construction process was carried out, according to the results of the simulation analysis, the key parts and links to be monitored in the construction process of steel structure were determined; according to the stress and displacement of the cantilever parts during construction,the principle of priority to dismantle the most disadvantageous support was determined, and the cantilever support was removed by stages. The above method had been successfully applied in this project, which provided certain reference for similar steel structure engineering.
2020, 35(10): 22-28.
doi: 10.13206/j.gjgS20032702
Abstract:
The large-span saddle shaped single-layer orthogonal cable net structure of national speed skating oval is the largest span and scale cable net structure in similar projects in the world. The specification and internal force of the cable are large. The load cable and stable cable are designed with double cables, which makes it difficult to lift and tension the cable. In addition, in the process of cable lifting and tensioning, the ring truss support has only vertical restraint, horizontal sliding, and ring truss support It is difficult to design and control the passive tension of the outer ring of truss curtain wall cable. How to solve the lifting and tension construction of large-span saddle shaped single-layer orthogonal cable net structure under the variable boundary conditions is the key to the construction of national speed skating Pavilion, which is directly related to whether the project can be completed on time.
In view of this situation, this paper systematically studies the cable fixed length design, installation error elimination, cable mesh weaving method, construction process simulation analysis, lifting tension construction and other aspects. It puts forward the concepts of fixed length cable installation, appropriate relaxation of synchronization requirements in the initial stage of cable network lifting, and the application of equal displacement synchronous tension forming in cable network tension stage The complete set of construction design and installation technology of large span saddle shaped single-layer orthogonal cable net structure, including calculation method, adjustable sleeve installation error elimination method, bearing pre deflection value design, construction simulation analysis, ground netting, phased, step-by-step, equal displacement integral lifting and tension forming technology. This technology solves the technical problem that the cable net structure is particularly sensitive to the construction error, successfully guides the construction of the cable net project of the national speed skating Pavilion, and ensures the smooth progress of the national speed skating hall project.
The large-span saddle shaped single-layer orthogonal cable net structure of national speed skating oval is the largest span and scale cable net structure in similar projects in the world. The specification and internal force of the cable are large. The load cable and stable cable are designed with double cables, which makes it difficult to lift and tension the cable. In addition, in the process of cable lifting and tensioning, the ring truss support has only vertical restraint, horizontal sliding, and ring truss support It is difficult to design and control the passive tension of the outer ring of truss curtain wall cable. How to solve the lifting and tension construction of large-span saddle shaped single-layer orthogonal cable net structure under the variable boundary conditions is the key to the construction of national speed skating Pavilion, which is directly related to whether the project can be completed on time.
In view of this situation, this paper systematically studies the cable fixed length design, installation error elimination, cable mesh weaving method, construction process simulation analysis, lifting tension construction and other aspects. It puts forward the concepts of fixed length cable installation, appropriate relaxation of synchronization requirements in the initial stage of cable network lifting, and the application of equal displacement synchronous tension forming in cable network tension stage The complete set of construction design and installation technology of large span saddle shaped single-layer orthogonal cable net structure, including calculation method, adjustable sleeve installation error elimination method, bearing pre deflection value design, construction simulation analysis, ground netting, phased, step-by-step, equal displacement integral lifting and tension forming technology. This technology solves the technical problem that the cable net structure is particularly sensitive to the construction error, successfully guides the construction of the cable net project of the national speed skating Pavilion, and ensures the smooth progress of the national speed skating hall project.
2020, 35(10): 29-33.
doi: 10.13206/j.gjgS20032701
Abstract:
Sensor arrangement scheme design is the most basic and key link in structural health monitoring, a good sensor arrangement scheme not only meets the requirements of structural health monitoring, but also needs to reduce the cost as much as possible to get the true response of the structure by minimizing the influence of errors such as noise, etc. as well as the requirements of the field environment.
In order to solve this problem, this paper proposes a method of optimal sensor placement based on modal confidence matrix. According to the modal matrix of the structure, the modal confidence matrix of the structure is calculated. Based on the principle of modal observability, the maximum value of the non diagonal element in the modal confidence matrix is selected as the evaluation standard, and the sensor layout scheme is optimized by iterative method. The specific operation steps are as follows:1)Determine the number of modes needed to be identified and the number of sensors needed for structural health monitoring, and determine the positions of all available measuring points according to the site environment; 2)Select a group of initial sensor measuring point layout. The initial measurement point scheme can be determined according to experience, which is less than the number of modes to be identified. The modal confidence matrix corresponding to the group of measuring points is calculated and the corresponding value of the largest non diagonal element is recorded; 3)Select one of the remaining optional measurement points to add to the current measurement point layout scheme, calculate the modal confidence matrix corresponding to the new measurement point scheme, and record the largest non diagonal element in the modal confidence matrix; 4)Replace the selected measuring points, repeat the calculation steps of the modal confidence matrix and record the maximum non diagonal elements. Repeat this step until all the points to be selected have been calculated. Compared with the maximum value of the non large diagonal elements of the modal confidence matrix corresponding to all the alternative test points, the smallest maximum non diagonal elements of the modal confidence matrix corresponding to the test points are selected to add to the current test point layout scheme; 5)Repeat steps 3) and 4) until the sensor measurement points and the maximum non diagonal element of the modal confidence matrix meet the requirements. For some complex structures, the maximum non diagonal element of the modal confidence matrix is less than 0.25.
According to the above methods, this paper takes the beam string structure as an example to establish the numerical model, and simulates the actual engineering environment, and carries out the trial calculation of the optimal arrangement of sensors. After trial calculation, the convergence of this method is good and the feasibility of calculation is high; it can effectively reduce the economic cost of sensor arrangement, reduce the influence of error factors, and improve the effectiveness and accuracy of modal identification. And according to the trial calculation of the example, this paper proposes:the iterative process of the step-by-step accumulation method can be divided into three stages:fast descent stage, stable stage and iterative end stage. The actual sensor arrangement scheme should be selected in the stable stage process to avoid using the results of iterative end stage as much as possible.
Sensor arrangement scheme design is the most basic and key link in structural health monitoring, a good sensor arrangement scheme not only meets the requirements of structural health monitoring, but also needs to reduce the cost as much as possible to get the true response of the structure by minimizing the influence of errors such as noise, etc. as well as the requirements of the field environment.
In order to solve this problem, this paper proposes a method of optimal sensor placement based on modal confidence matrix. According to the modal matrix of the structure, the modal confidence matrix of the structure is calculated. Based on the principle of modal observability, the maximum value of the non diagonal element in the modal confidence matrix is selected as the evaluation standard, and the sensor layout scheme is optimized by iterative method. The specific operation steps are as follows:1)Determine the number of modes needed to be identified and the number of sensors needed for structural health monitoring, and determine the positions of all available measuring points according to the site environment; 2)Select a group of initial sensor measuring point layout. The initial measurement point scheme can be determined according to experience, which is less than the number of modes to be identified. The modal confidence matrix corresponding to the group of measuring points is calculated and the corresponding value of the largest non diagonal element is recorded; 3)Select one of the remaining optional measurement points to add to the current measurement point layout scheme, calculate the modal confidence matrix corresponding to the new measurement point scheme, and record the largest non diagonal element in the modal confidence matrix; 4)Replace the selected measuring points, repeat the calculation steps of the modal confidence matrix and record the maximum non diagonal elements. Repeat this step until all the points to be selected have been calculated. Compared with the maximum value of the non large diagonal elements of the modal confidence matrix corresponding to all the alternative test points, the smallest maximum non diagonal elements of the modal confidence matrix corresponding to the test points are selected to add to the current test point layout scheme; 5)Repeat steps 3) and 4) until the sensor measurement points and the maximum non diagonal element of the modal confidence matrix meet the requirements. For some complex structures, the maximum non diagonal element of the modal confidence matrix is less than 0.25.
According to the above methods, this paper takes the beam string structure as an example to establish the numerical model, and simulates the actual engineering environment, and carries out the trial calculation of the optimal arrangement of sensors. After trial calculation, the convergence of this method is good and the feasibility of calculation is high; it can effectively reduce the economic cost of sensor arrangement, reduce the influence of error factors, and improve the effectiveness and accuracy of modal identification. And according to the trial calculation of the example, this paper proposes:the iterative process of the step-by-step accumulation method can be divided into three stages:fast descent stage, stable stage and iterative end stage. The actual sensor arrangement scheme should be selected in the stable stage process to avoid using the results of iterative end stage as much as possible.
2020, 35(10): 34-42.
doi: 10.13206/j.gjgS20072301
Abstract:
With the rapid development of the world economy, the traffic volume and load levels continue to increase. The bearing capacity of some large-span steel truss girder bridges can not meet the current needs and have experienced excessive deflection and stress under the effect of the existing load levels due to the low load level of the original design. To improve the bearing capacity and extend the service life, the structure need to be strengthened. After knowing about it, steel truss girder bridges can be strengthened by adding stay cable method, adding suspension cable method and external prestressing reinforcement method. Above those three methods, the stay cable method is the most effective.
Focusing this phenomenon, in this paper, a 128m steel truss bridge on the OMO River in Ethiopia is proposed to be reinforced by adding stay cable method. After looking up relevant information and considering the span of the steel truss bridge, plan to choose a 16m short tower and a 26m and a 30m conventional tower height. And establish the long-span steel truss bridge model by using the finite element method often used in bridge analysis and analyzes the influence of different tower heights on the reinforcement effect of the bridge under three load conditions from three aspects of stiffness, bearing capacity and stability respectively. Under the action of the first working condition, i.e. under the action of live road, analyze the deflection changes of steel truss bridge before and after the reinforcement of different tower heights; Under the second working condition, that is, under the standard load combination 1.0 constant load+1.0 live load in normal use limit state, the overall stability of the bridge after the reinforcement of the three towers with high stayed cables is analyzed, that is, the buckling analysis is conducted. Under the third working conditions, that is, the stress distribution of the upper chord, the lower chord and the inclined chord before and after the reinforcement is analyzed under the basis combination of 1.25 constant load and 1.75 live load in the ultimate bearing capacity state. The nodal plate is a key part of the steel truss girder with complex structure and uneven distribution of stress. In view of this situation, a solid model is established for the complex joints of steel truss bridge also by the finite element method. Components according to the node force transfer mainly through welding and friction type high strength bolt connection with the characteristics of the friction of the choice before and after reinforcement, to simulate the internal forc-e of the largest node plate axial force of each bar and internal and external bending moment on the corresponding bar, inside and outside nodes before and after the reinforcement plate stress, inside and outside helical rod bolt stress and inside and outside connection plate bolt stress analysis, understand the stress distribution characteristics.
After comprehen-sive consideration of the above analysis, the conclusion is drawn:when considering the reinforcement effect alone, the reinforcement effect brought by the 26 m tower high stay cable is the best, the reinforcement effect of the 16m tower high stay cable is slightly inferior to that of the 26m tower high stay cable, and the reinforcement effect of the 30m tower high stay cable is the worst. Considering the economic benefit of the project, it is suggested that the 16m tower stay cable should be used as the reinforcement scheme of the Omo River Bridge.
With the rapid development of the world economy, the traffic volume and load levels continue to increase. The bearing capacity of some large-span steel truss girder bridges can not meet the current needs and have experienced excessive deflection and stress under the effect of the existing load levels due to the low load level of the original design. To improve the bearing capacity and extend the service life, the structure need to be strengthened. After knowing about it, steel truss girder bridges can be strengthened by adding stay cable method, adding suspension cable method and external prestressing reinforcement method. Above those three methods, the stay cable method is the most effective.
Focusing this phenomenon, in this paper, a 128m steel truss bridge on the OMO River in Ethiopia is proposed to be reinforced by adding stay cable method. After looking up relevant information and considering the span of the steel truss bridge, plan to choose a 16m short tower and a 26m and a 30m conventional tower height. And establish the long-span steel truss bridge model by using the finite element method often used in bridge analysis and analyzes the influence of different tower heights on the reinforcement effect of the bridge under three load conditions from three aspects of stiffness, bearing capacity and stability respectively. Under the action of the first working condition, i.e. under the action of live road, analyze the deflection changes of steel truss bridge before and after the reinforcement of different tower heights; Under the second working condition, that is, under the standard load combination 1.0 constant load+1.0 live load in normal use limit state, the overall stability of the bridge after the reinforcement of the three towers with high stayed cables is analyzed, that is, the buckling analysis is conducted. Under the third working conditions, that is, the stress distribution of the upper chord, the lower chord and the inclined chord before and after the reinforcement is analyzed under the basis combination of 1.25 constant load and 1.75 live load in the ultimate bearing capacity state. The nodal plate is a key part of the steel truss girder with complex structure and uneven distribution of stress. In view of this situation, a solid model is established for the complex joints of steel truss bridge also by the finite element method. Components according to the node force transfer mainly through welding and friction type high strength bolt connection with the characteristics of the friction of the choice before and after reinforcement, to simulate the internal forc-e of the largest node plate axial force of each bar and internal and external bending moment on the corresponding bar, inside and outside nodes before and after the reinforcement plate stress, inside and outside helical rod bolt stress and inside and outside connection plate bolt stress analysis, understand the stress distribution characteristics.
After comprehen-sive consideration of the above analysis, the conclusion is drawn:when considering the reinforcement effect alone, the reinforcement effect brought by the 26 m tower high stay cable is the best, the reinforcement effect of the 16m tower high stay cable is slightly inferior to that of the 26m tower high stay cable, and the reinforcement effect of the 30m tower high stay cable is the worst. Considering the economic benefit of the project, it is suggested that the 16m tower stay cable should be used as the reinforcement scheme of the Omo River Bridge.
2020, 35(10): 43-50.
doi: 10.13206/j.gjgS20042301
Abstract:
Steel structure bridges are constructed in large sections and are prefabricated in factories. The precise setting out of the line shape of the plates is the most important for the precise control of the line shape of the steel structure manufacturing. The flying geese shaped steel structure arch rib curve is complex, and the height of the arch rib section changes linearly with the arch axis, which brings great difficulties to the manufacture and processing of the steel structure. The theoretical solution of the design of the bridge arch ribs to the bridge line and the pre-curvature line can provide the theoretical support for the subsequent processing and manufacturing of the steel structure arch rib top and floor, and the precise layout of the plates, and provide the guarantee for the stability of the steel structure arch rib after the bridge completed. The theoretical manufacturing line shape of prefabricated steel box arch ribs is an important technical indicator to ensure the smooth installation of the parabolic parabolic deformed section steel box arch bridge and the reasonable stress on the bridge during the service period.
Through the software MIDAS, the bridge theoretical calculation model was established, and the influence of construction process transformation on the arch rib bridge line shape, such as tensioning the prestressed tie bar, removing the arch rib mounting bracket, tensioning the suspender, removing the main beam under the bridge support, secondary tensioning suspender and so on, was analyzed. And the theoretical camber value of steel arch rib system transformation during construction and erection was obtained. Combined with the calculation equation of the arch axis of the special-shaped steel box arch rib given in the design drawings, the coordinate system of any point O point on the arch axis and the coordinate system B of the adjacent point B on the arch axis that was infinitely close to O point through the coordinate conversion method 2, and the original coordinate system of the whole bridge established the connection between the three. The triangle similarity relationship between the three was determined through the relationship between the position coordinate of point O in the original coordinate system, the position coordinate of point B, and the cross-sectional height H at point O in combination with coordinate system 1 and coordinate system 2. In order to obtain the geometric relationship between the top, bottom, diaphragm and hanger manufactured by the special-shaped steel box arch rib under the bridge state and the arch axis calculation equation, the independent bridge line shape of the steel box arch rib top and bottom plate determined the calculation equation.
The curve of the arch rib formed by this calculation formula was in good agreement with the design line given by the design institute. When x2-x1=0.5 m, the maximum deviation is 2 mm, which proved the correctness of this method. Then, through the calculation equations under the bridge completion state, combined with the pre-camber value of each point of the arch rib curve calculated by the MIDAS model, the calculation equations of the roof, bottom plate, diaphragm, and hanger of the steel structure arch rib without stress were solved. The curve state determined by this calculation equation was the line shape of the rigid arch rib without stress. Using this calculation result, the curve of the unstressed state was 80 mm longer than the design line of the completed bridge. This calculation method effectively solved the problem of precise setting out in the unstressed linear manufacturing process of the prefabricated factory of special-shaped steel box arch ribs.
Steel structure bridges are constructed in large sections and are prefabricated in factories. The precise setting out of the line shape of the plates is the most important for the precise control of the line shape of the steel structure manufacturing. The flying geese shaped steel structure arch rib curve is complex, and the height of the arch rib section changes linearly with the arch axis, which brings great difficulties to the manufacture and processing of the steel structure. The theoretical solution of the design of the bridge arch ribs to the bridge line and the pre-curvature line can provide the theoretical support for the subsequent processing and manufacturing of the steel structure arch rib top and floor, and the precise layout of the plates, and provide the guarantee for the stability of the steel structure arch rib after the bridge completed. The theoretical manufacturing line shape of prefabricated steel box arch ribs is an important technical indicator to ensure the smooth installation of the parabolic parabolic deformed section steel box arch bridge and the reasonable stress on the bridge during the service period.
Through the software MIDAS, the bridge theoretical calculation model was established, and the influence of construction process transformation on the arch rib bridge line shape, such as tensioning the prestressed tie bar, removing the arch rib mounting bracket, tensioning the suspender, removing the main beam under the bridge support, secondary tensioning suspender and so on, was analyzed. And the theoretical camber value of steel arch rib system transformation during construction and erection was obtained. Combined with the calculation equation of the arch axis of the special-shaped steel box arch rib given in the design drawings, the coordinate system of any point O point on the arch axis and the coordinate system B of the adjacent point B on the arch axis that was infinitely close to O point through the coordinate conversion method 2, and the original coordinate system of the whole bridge established the connection between the three. The triangle similarity relationship between the three was determined through the relationship between the position coordinate of point O in the original coordinate system, the position coordinate of point B, and the cross-sectional height H at point O in combination with coordinate system 1 and coordinate system 2. In order to obtain the geometric relationship between the top, bottom, diaphragm and hanger manufactured by the special-shaped steel box arch rib under the bridge state and the arch axis calculation equation, the independent bridge line shape of the steel box arch rib top and bottom plate determined the calculation equation.
The curve of the arch rib formed by this calculation formula was in good agreement with the design line given by the design institute. When x2-x1=0.5 m, the maximum deviation is 2 mm, which proved the correctness of this method. Then, through the calculation equations under the bridge completion state, combined with the pre-camber value of each point of the arch rib curve calculated by the MIDAS model, the calculation equations of the roof, bottom plate, diaphragm, and hanger of the steel structure arch rib without stress were solved. The curve state determined by this calculation equation was the line shape of the rigid arch rib without stress. Using this calculation result, the curve of the unstressed state was 80 mm longer than the design line of the completed bridge. This calculation method effectively solved the problem of precise setting out in the unstressed linear manufacturing process of the prefabricated factory of special-shaped steel box arch ribs.
