A prestressed cable vibration reduction structure system and design method inside a large cantilever awning column

Abstract

The present invention discloses a prestressed cable vibration damping structure system and design method inside the column of a large cantilever awning, including an awning. A front support column is connected below the middle and rear section of the awning. A hollow vertical tail column is connected to the rear end of the awning. A prestressed cable is arranged inside the tail column. One end of the prestressed cable is connected to the rear end of the awning, and the other end is anchored and fixed. The tail column itself has a spring-damper support that can vibrate vertically, or a spring-damper support that can vibrate vertically is arranged between the top of the tail column and the rear end of the awning. The spring-damper support is provided with a through hole, so that the prestressed cable passes through the through hole of the spring-damper support and can slide relative to the spring-damper support. By reasonably using building materials to resist overturning, the present invention can not only ensure the safety requirements of the building structure in tension under normal conditions, but also ensure the safety requirements of the building structure in compression under abnormal conditions, and at the same time, it does not affect the view of the audience.

Description

Technical Field

[0001] The present invention specifically relates to a prestressed cable vibration damping structure system and design method in a large cantilever awning column. Background Technique

[0002] In the field of civil engineering, there are many large cantilever structures in large-span space steel structure terminals, convention centers, railway stations, sports stadiums, etc. Figure 1 、 2 As shown, it is a large cantilever overhanging structure. The middle and rear ends of this cantilever structure resist the cantilever overturning through two columns, namely the front column and the tail column, and the front column is the main compression column.

[0003] In conventional design, according to the "Standard for Design of Steel Structures" GB50017, there are generally two design methods for such tail columns: one is that the upper and lower ends of the column are hinged to release the bending moment, and the tail column is only subjected to axial tension or axial pressure, that is, it is designed as a sway column, but this column does not have the ability to resist lateral forces, and the overall lateral resistance of the structure needs to be borne by other components. At this time, reducing the axial force of the column becomes the key. The methods that can be taken include reducing the roof load or densifying the column layout to reduce the axial force borne by each column, etc.;

[0004] The other method is that the upper and lower ends of the column are rigidly connected. In addition to bearing the axial force, the tail column also needs to bear the bending moment generated by the horizontal force (wind and earthquake) or the bending moment caused by the balance of the rigid connection node, that is, it is designed as a compression-bending or tension-bending member. This column has a certain ability to resist lateral forces. However, when the column height is relatively high, the column appears long and thin, and the lateral resistance it provides is limited. At this time, reducing the bending moment borne by the column is an effective means to optimize the cross-sectional form (circular, rectangular, special-shaped, etc.) or size. The strategy adopted is to divide and conquer. By increasing the stiffness of the lateral force resistance system such as shear walls or braces, the stiffness of the column is reduced, so as to reduce the stiffness ratio of the column and achieve the purpose of reducing the horizontal shear force borne by the column.

[0005] The above two methods have their own advantages and limitations, but they will all face the following problems caused by abnormal conditions such as strong typhoon action.

[0006] One is in terms of the allowable slenderness ratio structure of the column: According to the "Standard for Design of Steel Structures" GB50017, the allowable slenderness ratio of a compression member is 150, the allowable slenderness ratio of a tension member when it is compressed under the combined action of permanent load and wind load is 250, and the allowable slenderness ratio of a pure tension member is 400. Therefore, only from the aspect of structure, after the column is compressed, at the same height, the column cross-section needs to be increased by 1.6 - 2.6 times;

[0007] Second, in terms of component strength and stability: According to the "Standard for Design of Steel Structures" GB50017, the calculation formula for the stability of axially compressed members is as follows: N / ΨAf ≤ 1.0, where the stability coefficient Ψ is a coefficient less than 1.0, which is related to the slenderness ratio of the member, the yield strength of the steel, the cross-section type, etc. According to the above formula, it can be seen that after the column is compressed, at the same height, the column cross-section needs to be increased to meet the stability requirements.

[0008] In the above two conventional design methods, in order to ensure the safety of the structure, generally, methods such as increasing the structural cross-section and using high-strength materials are used to improve the stiffness and strength of the structure. In order to achieve the goal of making the tail column more slender, it is often necessary to increase the number of columns, reduce the roof load, add other lateral force resisting members, etc. Generally, it will ultimately affect the building effect and increase the project cost, which is not economically reasonable.

[0009] Therefore, in view of some limitations in the conventional design methods for the tail column in a large cantilever structure, the present invention proposes a prestressed cable vibration reduction structure system and design method for the tail column in a large cantilever awning. Summary of the Invention

[0010] One of the purposes of the present invention is a prestressed cable vibration reduction structure system for the tail column of a large cantilever awning. By reasonably using building materials to resist overturning, reducing the axial force when the cantilever tail column is compressed, making the tail column more slender, it can not only ensure the safety requirements of the building structure in tension under normal conditions, but also ensure the safety requirements of the building structure in compression under abnormal conditions.

[0011] The technical solution of the structural system of the present invention is as follows:

[0012] A prestressed cable vibration reduction structure system for the tail column of a large cantilever awning, including an awning, a front support column is connected below the middle and rear section of the awning, a hollow vertical tail column is connected to the rear end of the awning, a prestressed cable is arranged inside the tail column, one end of the prestressed cable is connected to the rear end of the awning, and the other end is anchored and fixed. The tail column itself has a spring damper support that can vibrate vertically or a spring damper support that can vibrate vertically is arranged between the top of the tail column and the rear end of the awning. The spring damper support is provided with a through hole, so that the prestressed cable passes through the through hole of the spring damper support and can slide relative to the spring damper support.

[0013] Under normal conditions, the structural system of the present invention forms a moment arm through the prestressed cables inside the front struts and the tail column to resist the downward overturning of the front end of the awning. By adjusting the cable forces of the prestressed cables, the deflection of the front end of the awning is controlled to ensure that the deflection remains within the design range. Under abnormal conditions, when there is a tendency for the front end of the awning to overturn upward, the tail column supports the rear end of the awning, enabling the rear end of the awning to be compressed to resist overturning. There is no need to connect wind-resistant cables to the front end of the awning, ensuring the view within the awning structure. The upper middle part of the tail column can be segmented, and a spring-damper support is set between the two segments, endowing the tail column with the function of vertical vibration reduction; according to different forms of building structures, a spring-damper support can also be set between the top of the tail column and the rear end of the awning, which can also achieve the effect of vertical vibration reduction for the tail column support. Furthermore, under abnormal conditions, the pressure borne by the tail column is regulated by the support. Under the same conditions, a thinner tail column can meet the design requirements, rationally utilizing the performance of building materials and saving building space.

[0014] The structural system of the present invention also has the following preferred designs:

[0015] The spring-damper support of the structural system of the present invention includes an upper support plate and a lower support plate. The upper support plate is connected with an upper connecting plate, and the lower support plate is connected with a lower connecting plate. The upper support plate and the lower support plate are connected through a number of uniformly distributed vertical spring devices and vertical damping devices. The vertical damping device includes a vertical insertion plate connected below the upper support plate and a vertical slot connected above the lower support plate and matching the vertical insertion plate. The vertical insertion plate is inserted into the vertical slot, and a viscoelastic material or viscous liquid is filled in the vertical slot to form a damping device.

[0016] The lower end of the front strut of the present invention is connected to the grandstand.

[0017] The awning of the present invention is in an inverted triangular shape, with the longest side of the triangle being the upper chord of the awning and the second longest side of the triangle being the lower chord of the awning.

[0018] The front strut of the present invention is a V-shaped structure with two support points connecting below the awning.

[0019] The tail column of the present invention is a steel pipe column.

[0020] In order to implement the above-mentioned large cantilever awning column internal prestressed cable vibration reduction structural system, the second object of the present invention is to propose a matching design method for this system. The design method mainly includes the following steps:

[0021] Step (1): Establish an analysis model of the large cantilever awning structural system, conduct conventional calculations and analyses and designs for dead loads, live loads, wind loads, seismic actions, etc., obtain the initial state and response of the structural system, and analyze the stress states of the tail column connected to the rear end of the awning truss under various working conditions;

[0022] In step (2), based on the structural system, structural layout, and the analysis results of step (1), comprehensively considering the architectural effect and the requirements of the usage function, the target component, namely the tail column, is initially selected as the analysis object;

[0023] In step (3), according to the analysis results of the analysis model in step (1) and the target component selected in step (2), the vertical fundamental frequency of the structural system and the deformation at the connection between the cantilever truss of the canopy and the top of the tail column are judged, and the spring-damping parameters of the spring-damping support are initially determined;

[0024] In step (4), the time-history load is input as the external excitation load, and the time-history nonlinear calculation analysis of the structural system is carried out. Generally, the wind load time-history or the vertical seismic wave time-history can be selected as the time-history load;

[0025] In step (5), for the overall assembly and structural design analysis, after selecting the cable and spring-damping parameters, they are assembled in the overall model. Repeat steps (3) to (5), set different spring parameters, damping parameters, and different load time-histories, and conduct multi-parameter calculation analysis to select the optimal parameters.

[0026] One of the effect evaluation criteria in this design method: The vertical deformation of the cantilever end of the structure designed by this method is basically the same as that designed by the conventional method, and the prestressed cable tension is accurately controlled; Two: Under the strong wind condition, the optimization rate λ of the axial pressure of the steel column is greater than 10%,

[0027]

[0028] Among them, N0 is the axial force of the steel column under the conventional system and method, and N1 is the axial force of the steel column under the structural system and method of the present invention.

[0029] Compared with the prior art, the present invention has the following remarkable effects:

[0030] In the present invention, the tail column, prestressed cable, and spring-damping support of the cantilever structural system are integrally combined. The cable is hidden inside the tail column. The design concept is novel, the structure is compact, the building space is saved, the appearance is simple and clear, the cable is not exposed to the air, the durability of the cable can be improved, the maintenance cost can be reduced, and there is no need to set a stabilizing cable at the front end of the canopy, ensuring a wide view of the cantilever structure.

[0031] The present invention makes full use of the high-strength tensile performance of the prestressed cable inside the tail column to resist the tendency of the front end of the canopy to overturn downward; compared with the prior art, the tail column is not subject to axial force under normal conditions. The tail column is mainly used to resist the tendency of the front end of the canopy to overturn upward under abnormal conditions and is subjected to less pressure, so the lower section of the tail column can be reduced, and the same design requirements can be achieved with a slender tail column.

[0032] Under abnormal working conditions such as vertical earthquake or strong wind suction, the present invention can achieve energy dissipation and shock absorption by utilizing the reciprocating motion of the spring-damper bearing. By selecting spring-damper bearings with different spring stiffness and damping parameters, the pressure on the stern post can be adjusted, and the stern post can be designed to be more slender.

[0033] The present invention applies a prestressing cable to the awning to apply a prestressing force, which can more precisely control the deflection at the front end of the awning, and there is no need to increase the height of the awning truss or increase the cross-section of the members on the cantilever to improve the stiffness to control the front-end deflection. Brief Description of the Drawings

[0034] The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0035] Figure 1 It is an analysis model diagram of a vibration reduction structure system of prestressed cables in the columns of a large cantilever awning according to the present invention;

[0036] Figure 2 The schematic diagram of the principle of the large cantilever awning structure system of the present invention;

[0037] Figure 3 For Figure 2 The enlarged view at the middle support node A, where the support is a vertical sectional view;

[0038] Figure 4 The horizontal sectional view of the spring-damper bearing;

[0039] Figure 5 It is a schematic diagram of the force mechanism of the structure system of the present invention under normal working conditions;

[0040] Figure 6 It is a schematic diagram of the force mechanism of the structure system of the present invention under abnormal working conditions;

[0041] Figure 7 It is a schematic diagram of the principle of a conventional designed cantilever awning in the comparative example. Detailed Description of the Invention

[0042] As Figure 1 Shown is an analysis model of a vibration reduction structure system of prestressed cables in the columns of a large cantilever awning. In this embodiment, 9 stern posts 1a - 1i of this structure system are used as the target components for analysis.

[0043] Figures 2 to 5Shown is a prestressed cable vibration damping structure system inside a large cantilever awning column, including an awning a. A front support column 4 is connected below the middle and rear sections of the awning a. A hollow vertical tail column 1 is connected to the rear end of the awning a. A prestressed cable 2 is arranged inside the tail column 1. One end of the prestressed cable 2 is connected to the rear end of the awning a, and the other end is anchored and fixed. The upper and middle parts of the tail column 1 are in two sections, and a spring-damper support that can vibrate vertically is arranged between the two sections. The spring-damper support is provided with a through hole 37, so that the prestressed cable 2 passes through the through hole 37 of the spring-damper support and can slide relative to the spring-damper support.

[0044] In this embodiment, the tail column 1 itself has a spring-damper support, enabling the tail column itself to have the function of vertical vibration damping; according to different forms of building structures, a spring-damper support can also be arranged between the top of the tail column and the rear end of the awning, which can also enable the tail column support to achieve the effect of vertical vibration damping.

[0045] As a preferred embodiment:

[0046] The spring-damper support described in the present invention includes an upper support plate 32 and a lower support plate 35. The upper support plate 32 is connected with an upper connecting plate 31, and the lower support plate 35 is connected with a lower connecting plate 36. The upper support plate 32 and the lower support plate 35 are connected by a number of vertically distributed vertical spring devices and vertical damping devices. The vertical damping device includes a vertical insertion plate 33 connected below the upper support plate 32 and a vertical slot 34 connected above the lower support plate 35 and matching with the vertical insertion plate 33. The vertical insertion plate 34 is inserted into the vertical slot 34, and a viscoelastic material or viscous liquid is filled in the vertical slot 34 to form a damping device.

[0047] The lower end of the front support column 4 is connected to a grandstand c.

[0048] The awning a is in an inverted triangular shape. The longest side of the triangle is the upper chord a1 of the awning a, and the second longest side of the triangle is the lower chord a2 of the awning a.

[0049] The front support column 4 is a V-shaped structure and has two support points connecting below the awning a.

[0050] The tail column 1 is a steel pipe column.

[0051] As Figure 5 shown, in the normal working condition of the structure system,

[0052] When the cantilever is subjected to normal dead load + live load and under the vertical downward acting force, the force transmission path in the cable direction is: the upper chord of the awning is in tension → prestressed cable → lower structure (foundation). At this time, the tail column and the support are not stressed; the force transmission path in the direction of the front support column is: the lower chord of the awning is in compression → front support column → grandstand → lower structure (foundation); the whole structure system is in one tension and one compression, effectively resisting overturning.

[0053] As Figure 6As shown, in the abnormal working conditions of the structural system, such as the strong typhoon load exceeding the self-weight of the structure, in this embodiment, the model is simplified to a vertically upward acting force on the cantilever. In such a working condition, the prestressed cable becomes slack and is not stressed. The force transmission path in the direction of the tail column is: the upper chord of the awning is compressed → the support is compressed → the tail column → the lower structure (foundation); the force transmission path in the direction of the front strut is: the lower chord of the awning is tensioned → the front strut → the grandstand → the lower structure (foundation); the whole structural system is in a state of one tension and one compression, effectively resisting overturning.

[0054] The tail column, prestressed cable and spring damper support of the cantilever structural system of the present invention are integrally combined, and the cable is hidden inside the tail column. The structure is compact, saving building space, with a simple and clear appearance. The cable is not exposed to the air, which can improve the durability of the cable and reduce the maintenance cost. There is no need to set a stabilizing cable at the front end of the awning, ensuring a wide field of vision for the cantilever structure.

[0055] All the tensile forces of the cantilever structural system of the present invention are borne by the prestressed cable, and the tail column is used to be compressed under abnormal working conditions to resist the overturning of the cantilever.

[0056] The design method and specific implementation steps of the above-mentioned vibration reduction structural system of the prestressed cable in the large cantilever awning column are as follows:

[0057] Step (1) Establish an analysis model of the large cantilever awning structural system, conduct conventional calculations and analyses and designs of dead load, live load, wind load and seismic action, etc., obtain the initial state and response of the structural system, and analyze the stress state of the tail column connected to the rear end of the cantilever truss of the awning under various working conditions; in this embodiment, MIDAS / Gen is used as the finite element analysis software to establish an analysis model of a large cantilever stadium awning structure and conduct analysis and design. Figure 1 Shown in the figure is the three-dimensional model of a part of the awning structural system of the stadium.

[0058] Step (2) According to the structural system, structural layout and the analysis results of step (1), comprehensively considering the architectural effect and the requirements of the use function, initially select the target component, that is, the tail column, as the analysis object.

[0059] As Figure 1 shown, a total of 9 tail columns, namely tail columns 1a to 1i, are selected as the target components. The heights of these tail columns are between 20m and 27m, and they are initially designed according to the conventional design method. The cross-sectional diameter of the tail column needs to be 800mm to 1200mm. Since the tail column area belongs to the exposed area, the architectural design hopes to achieve a slender effect for the tail column, while the cross-sectional size of 800mm to 1200mm is relatively large, which does not meet the architectural requirements. Therefore, 9 tail columns are selected as the research and analysis objects of this embodiment to further illustrate the technical effects of the structural system of the present invention.

[0060] Step (3) determines the vertical fundamental frequency of the structural system and the deformation at the connection between the awning cantilever truss and the top of the tail column based on the analysis results of the analysis model in step (1) and the target component selected in step (2), and preliminarily determines the spring-damping parameters of the spring-damping support;

[0061] Preliminarily determine the spring stiffness according to the following formula:

[0062] K = M×(2πf)^2

[0063] Where M is the axial force borne by the tail column and f is the fundamental frequency of the structure.

[0064] According to the fundamental frequency of the structure and the vertical deformation of the top of the tail column, preliminarily determine

[0065] the damping parameter according to the following formula:

[0066] V = 2πAf

[0067] K = C×(V)^α

[0068] Where A represents the stroke (deformation) of the damper, f is the fundamental frequency of the structure, C is the damping coefficient, V is the running speed, and α is the damping index.

[0069] Step (4) Input the time-history load as the external excitation load and perform the time-history nonlinear calculation analysis on the structural system. Generally, the time-history load can be selected as the wind load time-history or the vertical seismic wave time-history;

[0070] The research object of this embodiment is located on the coast in a strong typhoon area, and the wind load time-history is selected as the external excitation load. There are generally three methods to determine the wind time-history load: one is to obtain the wind time-history of the target range through CFD numerical wind tunnel simulation; the second is obtained through wind tunnel tests. Generally, complex structures need to determine the wind load through wind tunnel tests. The wind pressure time-history is obtained through wind tunnel tests, and the load data is generally accurate, reliable and easy to obtain; the third is the actual typhoon monitoring data. This data is generally difficult to obtain, and the monitoring points are often not in the same location as the actual project, and the influence of the actual project's shape is not considered.

[0071] Therefore, in this embodiment, the wind load time-history is obtained according to the wind tunnel test results and implemented. The monitoring data points of the wind tunnel test are generally fewer than the number of nodes on the roof of the structural finite element model. Therefore, the principle of dividing into regions and slices is adopted, and the wind load time-history of each monitoring point is input into the model according to its influence area.

[0072] Step (5) Overall assembly and structural design analysis. After selecting the cable and spring-damping parameters, assemble them in the overall model, repeat steps (3) to (5), set different spring parameters, damping parameters, and different load time-histories, and perform multi-parameter calculation analysis to select the optimal parameters.

[0073] One of the effect evaluation criteria in this design method: The vertical deformation at the cantilever end of the structure designed according to this method is basically the same as that designed by the conventional method, and the prestressed cable tension is accurately controlled;

[0074] The second evaluation criterion: Under the action of strong wind conditions, the axial pressure optimization rate λ of the steel column is greater than 10%,

[0075]

[0076] wherein, N0 is the axial force of the steel column under the conventional system and method, and N1 is the axial force of the steel column under the structural system and method of the present invention.

[0077] Table 1 below shows the comparison of the advantages and disadvantages between the structural system and design method of the present invention and the conventional system and design method. The awning model of the conventional system and method as a comparative example is as Figure 7 shown. The tail column and the end of the cantilever truss are connected by full penetration welding, and the bending moment is not released, and the internal force of the truss can be directly transmitted to the tail column.

[0078] In Table 1, the deformation is under the condition of applying 1.0 times the dead load + 1.0 live load (the dead load mainly includes the self-weight of the structural members, the weight of decoration and the weight of the roof, and the live load mainly refers to the variable load generated when considering the maintenance of people on the roof or the accumulation of dust or water when it rains. The 1.0 coefficient is the partial coefficient considered in different load combinations according to the national standard "Load Code for Building Structures". Taking 1.0 means not considering amplification or reduction), the vertical deformation at the connection between the rear end of the cantilever truss and the top of each tail column. A negative value indicates downward compression deformation. The axial force of the steel column is the axial force received by each tail column under the condition of applying 1.0 times the dead load + 1.5 times the wind load. A negative value indicates that the tail column is compressed. By comparison, through a large cantilever awning column internal prestressed cable vibration reduction structural system and its design method of the present invention, on the premise that all the tensile force is borne by the cable, the axial pressure optimization rate of the tail column is between 10% and 47%. Finally, the tail column can be designed as a cylindrical column with a diameter of 600 mm, making it more slender and the optimization effect is obvious.

[0079] Table 1

[0080]

[0081] The above embodiments of the present invention do not limit the protection scope of the present invention, and the implementation manners of the present invention are not limited thereto. All these modifications, substitutions or changes made to the above structure of the present invention according to the above content of the present invention, in accordance with the common general knowledge and conventional means in the art, without departing from the above basic technical idea of the present invention, shall fall within the protection scope of the present invention.

Claims

1. A prestressed cable vibration damping structural system inside the column of a large cantilever awning, comprising an awning, wherein a front support column is connected below the middle and rear sections of the awning, and is characterized in that, The rear end of the canopy is connected to a hollow vertical tail column. A prestressed cable is arranged inside the tail column. One end of the prestressed cable is connected to the rear end of the canopy, and the other end is anchored and fixed. The tail column itself is provided with a spring-damper support capable of vertical vibration reduction, or a spring-damper support capable of vertical vibration reduction is arranged between the top of the tail column and the rear end of the canopy. The spring-damper support is provided with a through hole, so that the prestressed cable passes through the through hole of the spring-damper support and can slide relative to the spring-damper support; The spring-damper support includes an upper support plate and a lower support plate. The upper support plate is connected with an upper connecting plate, and the lower support plate is connected with a lower connecting plate. The upper support plate and the lower support plate are connected by a plurality of vertically distributed vertical spring devices and vertical damping devices. The vertical damping device includes a vertical insertion plate connected below the upper support plate and a vertical slot connected above the lower support plate and matching with the vertical insertion plate. The vertical insertion plate is inserted into the vertical slot, and a viscoelastic material or viscous liquid is filled in the vertical slot to form a damping device.

2. The prestressed cable vibration damping structural system inside the large cantilever awning column according to claim 1, characterized in that, The lower end of the front support column is connected to the grandstand.

3. The prestressed cable vibration damping structure system inside the large cantilever awning column according to claim 2, characterized in that, The canopy is in an inverted triangular shape. The longest side of the triangle is the upper chord of the canopy, and the second longest side of the triangle is the lower chord of the canopy.

4. The prestressed cable vibration damping structural system inside the large cantilever awning column according to claim 3, characterized in that, The front support column is a V-shaped structure and has two support points connecting below the canopy.

5. The prestressed cable vibration damping structural system inside the large cantilever awning column according to claim 1, characterized in that, The tail column is a steel pipe column.

6. A design method for the prestressed cable vibration damping structure system inside the large cantilever awning column according to any one of claims 1 to 5, characterized in that It includes the following steps: Step (1): Establish an analysis model of the large cantilever canopy structure system, conduct conventional calculations and analyses of dead load, live load, wind load and seismic action, obtain the initial state and response of the structure system, and analyze the stress state of the tail column connected to the rear end of the cantilever truss of the canopy under various working conditions; Step (2): According to the structure system, structural layout and the analysis results of step (1), and comprehensively considering the building effect and the use function requirements, initially select the target component, that is, the tail column, as the analysis object; Step (3): According to the analysis results of the analysis model in step (1) and the target component selected in step (2), judge the vertical fundamental frequency of the structure system and the deformation at the connection between the cantilever truss of the canopy and the top of the tail column, and initially determine the spring-damper parameters of the spring-damper support; Step (4): Input the time-history load as the external excitation load and conduct non-linear time-history calculation and analysis of the structure system; Step (5): Overall assembly and structural design analysis. After selecting the cable and spring-damper parameters, assemble them in the overall model; Repeat steps (3) to (5), set different spring parameters, damping parameters and different load time histories, conduct multi-parameter calculation and analysis, and select the optimal parameters.

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