Integral design method for skylight frame and roof truss of large-span building structure

Abstract

The invention relates to an integrated design method for a skylight frame and a roof truss of a large-span building structure, which is characterized in that the skylight frame and the roof truss are combined to form an integrally stressed combined large truss, a force transmission path of a traditional split design is changed, and a special hinged sliding node is adopted to realize the unification of reliable force transmission and temperature deformation release; according to the method, secondary internal force and stress concentration caused by deformation incoordination and the temperature effect are fundamentally eliminated, the upper chord axial force of the roof truss is reduced, the midspan rigidity is improved, the steel consumption is effectively reduced, and economic benefits are achieved.

Description

Technical Field

[0001] This application relates to the field of building engineering technology, and in particular to an integrated design method for skylight frames and roof trusses in large-span building structures. Background Technology

[0002] In large-span industrial plants, warehouses, stadiums and other buildings, installing steel structure roof ventilation skylights, also known as skylight frames, is a common technical means to improve indoor air circulation, natural lighting and reduce energy consumption. As a key structure that supports and encloses the skylight opening, the safety of the skylight frame itself, as well as its connection method with the main load-bearing structure, such as the roof truss, is crucial to the stability and economy of the entire roof system.

[0003] In existing practices for designing large-span building structures, roof trusses and skylight frames are typically designed as two independent structural units, with simple assembly connections made at the corresponding positions on the upper chord of the roof truss. While this long-standing design method has a standardized process, it has revealed numerous insurmountable drawbacks under specific engineering conditions, particularly in areas where the roof truss span exceeds 30 meters and the annual temperature difference at the building site exceeds 40°C. First, under the solid design model, the mechanical models of the skylight frame and the roof truss are independent of each other, resulting in uncoordinated deformation of the two under load. That is, the load of the skylight frame is simplified as a concentrated force or a uniformly distributed load applied to the upper chord of the roof truss. The force transmission path is discontinuous, and the collaborative work between the structures is not achieved, resulting in a large structural redundancy. According to statistics, the amount of steel used in typical projects increases by about 10% as a result.

[0004] Secondly, in regions with significant annual temperature differences, the thermal expansion and contraction effect of steel structures is extremely pronounced, meaning that large-span roof trusses will experience considerable lateral expansion and contraction deformation. However, traditional split-design connection nodes, such as the welded joints commonly used in actual construction, create a semi-rigid connection that does not conform to the design assumption, which is usually an ideal hinged connection. This connection cannot fully constrain deformation, nor can it freely release deformation, resulting in huge thermal stress between the skylight frame and the roof truss when the temperature changes. This seriously threatens the safety of the connection node and may lead to premature fatigue failure of the components. Summary of the Invention

[0005] To address the aforementioned issues, this application provides an integrated design method for skylight frames and roof trusses in large-span building structures, which effectively enhances the safety and economy of such structures.

[0006] To achieve the above objectives, the integrated design method for skylight frames and roof trusses in large-span building structures proposed in this application includes the following steps: A) Establish the finite element model of the roof truss and the finite element model of the skylight frame; B) Combine the finite element model of the skylight frame with the finite element model of the roof truss to form a unified finite element model that is structurally coordinated under stress; C) In the overall finite element model, a hinged sliding node is set at the connection between the skylight frame and the roof truss. The hinged sliding node is set to transmit only axial force and shear force, while releasing bending moment constraints and temperature deformation constraints along the transverse direction of the roof truss. D) Perform structural analysis on the overall finite element model after applying the load to obtain the internal force analysis results of the model; E) Based on the internal force analysis results, optimize the design of the components within the combined truss area formed by the roof truss and skylight frame.

[0007] Preferably, the internal force analysis results include, but are not limited to, component axial force, shear force, bending moment, stress, and displacement data.

[0008] Preferably, step A specifically includes: establishing the finite element model of the roof truss based on the national standard roof truss drawing set, and establishing the finite element model of the skylight frame based on the national standard skylight frame drawing set.

[0009] Preferably, the combined truss region is defined as the structural region jointly enclosed in the vertical plane by the skylight frame and the roof truss portion spanned below it; and the optimization design in step E includes at least the selection of cross-sections for the roof truss and skylight frame components within the combined truss region.

[0010] Preferably, based on the results of the optimization design, the performance parameters required to realize the articulated sliding node are determined.

[0011] Preferably, the performance parameters include the required sliding amount of the hinged sliding node, which is determined based on the thermal expansion deformation calculation formula of the roof truss ΔL1=α·L1·ΔT; where α is the linear expansion coefficient of the roof truss, L1 is the span of the roof truss, and ΔT is the maximum annual temperature difference in the region where the large-span building structure is located.

[0012] Preferably, the performance parameters further include the design value of the shear bearing capacity and the coefficient of sliding friction of the hinged sliding node.

[0013] Preferably, the hinged sliding node includes a sliding component and a shear-resistant component, and the bottom end of the skylight frame column is provided with a column end plate, wherein: The sliding component includes: At least one PTFE plate is disposed between the column end plate and the upper chord of the roof truss; An oblong hole is formed on the end plate of the column, and its length direction is consistent with the transverse direction of the upper chord of the roof truss; Bolts, passing through the elongated holes, are used to slidably connect the column end plate to the upper chord of the roof truss; The shear-resistant component includes: At least one trapezoidal shear key is fixed to the upper surface of the upper chord of the roof truss; A shear groove matching the trapezoidal shear key is formed on the side of the column end plate and is used to accommodate the trapezoidal shear key.

[0014] Preferably, the trapezoidal shear keys are arranged in pairs on two opposite sides of the column end plate, and each pair of two trapezoidal shear keys has a bearing slope that slopes inward toward each other, with the slope angle being 5° to 10°.

[0015] Preferably, the length L2 of the oblong hole satisfies the formula: L2≥2R+ΔL2; where R is the radius of the bolt and ΔL2 is the maximum thermal expansion deformation of the roof truss under the design conditions.

[0016] The integrated design method for skylight frames and roof trusses in large-span building structures proposed in this application combines the skylight frames and roof trusses into a single, load-bearing composite truss. This changes the force transmission path of traditional separate designs and utilizes dedicated hinged sliding nodes to achieve a balance between reliable force transmission and temperature deformation release. This method not only fundamentally eliminates secondary internal forces and stress concentrations caused by deformation incoordination and temperature effects, but also reduces the axial force of the roof truss's upper chord, increases mid-span stiffness, and effectively reduces steel consumption, resulting in economic benefits. Attached Figure Description

[0017] Figure 1 It is an overall finite element model formed by combining the roof truss and skylight frame finite element models provided in the embodiments of this application.

[0018] Figure 2 This is a comparison diagram of axial force between the overall finite element model provided in the embodiments of this application and the traditional split design model.

[0019] Figure 3 This is a comparison diagram of the vertical displacement between the overall finite element model provided in this application embodiment and the traditional split design model.

[0020] Figure 4 This is a schematic diagram of the planar structure of the hinged sliding node provided in the embodiment of this application.

[0021] Figure 5 This is a schematic diagram of the structural fit between the trapezoidal shear key and the shear groove provided in the embodiments of this application.

[0022] Figure 6 This is a schematic diagram of the planar structure of the hinged sliding node provided in the embodiment of this application from another perspective.

[0023] Figure 7 This is a three-dimensional structural schematic diagram of the hinged sliding node provided in the embodiment of this application.

[0024] Figure 8 This is a schematic diagram of the anti-shear groove provided in an embodiment of this application.

[0025] Among them: roof truss 10, skylight frame 20, hinged sliding node 30, combined truss area 40, skylight frame column 1, column end plate 2, PTFE plate 3, top chord 4, trapezoidal shear key 5, shear groove 6, oblong hole 7, bolt 8. Detailed Implementation

[0026] The preferred embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0027] This embodiment provides an integrated design method for the skylight frame 20 and roof truss 10 in a large-span building structure, and illustrates it using a typical engineering project as an example. For instance, a typical industrial plant has a steel roof truss structure with a span of 30 meters, a height of 1.5 meters at the ends, a mid-span height of 3.0 meters, a total steel roof truss span of 9 meters, and a height of approximately 3.5 meters. The longitudinal column spacing of the plant is 6.0 meters, and the roof dead load and live load are assumed to be 1.0 kN / m². 2 Basic wind pressure 0.5 kN / m 2 The earthquake fortification intensity is 7 degrees 0.1g, the earthquake group is Group 2, the site category is Class III, and the factory is located in an area where the annual temperature difference can reach 60℃.

[0028] See Figures 1 to 8 As shown, the design method described in this embodiment specifically includes the following steps: A) Establish the finite element model of the roof truss 10 and the skylight frame 20.

[0029] Preferably, a finite element model of the roof truss 10 is established based on the national standard roof truss 10 drawing set, and a finite element model of the skylight frame 20 is established based on the national standard skylight frame 20 drawing set. Specifically, based on the national standard drawing set "Steel Roof Trusses" (05G515), a steel roof truss of model GWJ30-5 can be selected as the foundation, and a finite element model of the roof truss 10 can be established in finite element analysis software, such as MIDAS Gen; simultaneously, based on the national standard drawing set "Steel Skylight Frames" (05G516), a steel skylight frame of model GCJ9-11 can be selected as the foundation, and a finite element model of the skylight frame 20 can be established. Of course, in actual design, appropriate components can be selected according to the stress.

[0030] B) Combine the finite element model of the skylight frame 20 with the finite element model of the roof truss 10 to form a unified finite element model that structurally shares the load. That is, combine the independently established finite element model of the skylight frame 20 with the finite element model of the roof truss 10, placing the skylight frame 20 at a predetermined position on the upper chord of the mid-span of the roof truss 10, thereby forming a unified finite element model that structurally shares the load. In this model, the skylight frame 20 is no longer a simple load; its components participate in the load-bearing process as part of the overall structure.

[0031] C) In the overall finite element model, a hinged sliding node 30 is set at the connection between the skylight frame 20 and the roof truss 10. The hinged sliding node 30 is set to transmit only axial force and shear force, while releasing bending moment constraints and temperature deformation constraints along the transverse direction of the roof truss 10.

[0032] Specifically, in the combined overall finite element model, special boundary conditions are set at each connection between the skylight frame 20 and the roof truss 10 to simulate the hinged sliding nodes 30. These boundary conditions are specifically set as follows: mechanically, only axial force (vertical force) and shear force (horizontal force) are transmitted at the connection nodes; simultaneously, the bending moment constraint at the nodes is completely released, and the displacement constraint along the transverse direction of the roof truss 10 is also released. This setting accurately reproduces the core function of the physical nodes in the virtual model—reliable force transmission while allowing temperature-induced deformation and sliding.

[0033] D) Perform structural analysis on the overall finite element model after applying loads to obtain the internal force analysis results of the model. Specifically, in this step, structural analysis calculations are performed on the overall finite element model under design conditions such as dead load, live load, wind load, and temperature load to obtain the internal force analysis results of the overall model. In this embodiment, the internal force analysis results are a series of quantitative data sets, mainly including the axial force, shear force, bending moment, stress of each component, and displacement data of each node, to provide accurate data basis for subsequent optimization.

[0034] E) Based on the internal force analysis results, the components within the combined truss region 40 formed by the roof truss 10 and the skylight frame 20 are optimized.

[0035] In specific implementation, such as Figure 1 As shown, firstly, a combined truss region 40 is defined, which is geometrically a structural region jointly enclosed in the vertical plane by the skylight frame 20 and the roof truss 10 section that it spans below; then, the cross-section selection optimization is performed on all components within the combined truss region 40, that is, the components including the original roof truss 10 and skylight frame 20.

[0036] Reference Figure 2As shown in the figure, the upper part of the figure is the axial force diagram of the embodiment model of this application, and the lower part is the axial force diagram of the comparative model of the traditional split design. It can be seen from the figure that in the comparative model of the traditional split design, the maximum axial pressure of the roof truss upper chord member within the skylight frame range is calculated to be 511kN. However, in the embodiment model using the integrated design method of this application, due to the formation of a combined large truss to cooperate in bearing the force, the original force transmission path is changed, and the maximum axial pressure at this position is reduced to 471kN, a reduction of about 8%.

[0037] At the same time, refer to Figure 3 As shown in the figure, the upper part of the figure is the vertical displacement diagram of the comparison model, and the lower part is the vertical displacement diagram of the model of the embodiment of the present invention. It can be seen intuitively from the displacement comparison diagram that the maximum vertical displacement at mid-span of the model of the embodiment of the present invention is smaller than that of the comparison model, and the vertical stiffness at mid-span of its overall structure is improved by about 2%.

[0038] In summary, by comparing and analyzing the results, after identifying components that are subjected to excessive stress or have excessive stress reserves, their cross-sectional dimensions are increased or decreased accordingly until the stress levels of all components are within a reasonable and economical range. This effectively reduces the internal forces of key components and improves the overall stiffness of the structure.

[0039] In some embodiments, based on the results of the above-described optimization design, the performance parameters required to realize the hinged sliding node 30 are determined, that is, the hinged sliding node 30 of the physical component that realizes the above-described function is specifically designed.

[0040] Specifically, the performance parameters include the required sliding amount of the hinged sliding node 30, which is determined based on the thermal expansion deformation calculation formula of the roof truss 10: ΔL1 = α·L1·ΔT; where α is the linear expansion coefficient of the roof truss 10, L1 is the span of the roof truss 10, and ΔT is the maximum annual temperature difference in the region where the large-span building structure is located. Substituting the parameters: the linear expansion coefficient of steel α = 1.2 × 10⁻ 5 With a temperature of / ℃, a span of L1=30000mm for roof truss 10, and a maximum annual temperature difference ΔT=60℃, the calculated maximum thermal expansion deformation ΔL1=21.6mm. Therefore, the designed hinged sliding node 30 must have a sliding capacity of not less than ±22mm.

[0041] On the other hand, the performance parameters also include the design value of the shear bearing capacity and the coefficient of sliding friction of the hinged sliding node 30. In specific implementation, the maximum shear force value can be extracted from the internal force analysis results to determine that the design value of the shear bearing capacity of the node must not be less than 200kN; at the same time, to ensure smooth sliding, the coefficient of sliding friction μ is required to be no greater than 0.1.

[0042] In some embodiments, such as Figures 4 to 8As shown, the hinged sliding node 30 includes a sliding component and a shear-resistant component, and a column end plate 2 is provided at the bottom end of the skylight frame 20 column 1. In this embodiment, the sliding component is disposed between the column end plate 2 and the roof truss upper chord 4, and is used to enable the column end plate 2 to slide horizontally relative to the roof truss upper chord 4 to release temperature stress; while the shear-resistant component is used to transmit the horizontal shear force between the column end plate 2 and the roof truss upper chord 4, such as the horizontal shear force caused by wind load, seismic action, etc., while allowing the horizontal sliding.

[0043] Specifically, the sliding component includes: At least one PTFE plate 3 is disposed between the column end plate 2 and the upper chord 4 of the roof truss. PTFE (polytetrafluoroethylene) material has an extremely low coefficient of friction; in this embodiment, a PTFE plate with a coefficient of friction not greater than 0.1 is preferably used. To further improve sliding performance and durability, such as... Figure 4 As shown, two layers of PTFE boards 3 can be installed.

[0044] Elongated hole 7: It is opened on the column end plate 2, and its length direction is consistent with the transverse direction of the upper chord 4 of the roof truss, that is, consistent with the expected direction of thermal expansion and contraction.

[0045] Bolt 8: Passes through the elongated hole 7 and is used to slidably connect the column end plate 2 to the roof truss upper chord 4. That is, the bolt 8 passes through the elongated hole 7 on the column end plate 2 and is fastened to the roof truss upper chord 4. The shank of the bolt 8 can move freely within the length of the elongated hole 7, thus constituting the sliding stroke. In this embodiment, the bolt 8 mainly bears the vertical load and acts as a limiter for the column end plate 2, preventing it from slipping excessively or detaching.

[0046] To ensure sufficient slippage to fully release temperature deformation, the length L2 of the oblong hole 7 should satisfy the formula: L2≥2R+ΔL2, where R is the radius of the bolt 8, and ΔL2 is the maximum thermal expansion deformation of the roof truss upper chord 4 under design conditions, which is the maximum design thermal expansion deformation of the roof truss upper chord 4 calculated based on the structural span, the material linear expansion coefficient, and the maximum annual temperature difference in the region. For example, if an M16 bolt (R=8mm) is used, and the maximum thermal expansion deformation ΔL2 calculated above is 22mm, then the length L2 of the oblong hole 7 should not be less than 2*8+22=38mm.

[0047] See Figure 5 , Figure 7 and Figure 8 As shown, the shear-resistant component includes: At least one trapezoidal shear key 5 is fixed to the upper surface of the upper chord 4 of the roof truss by means of welding or other methods.

[0048] Shear groove 6: It is formed on the side of the column end plate 2, and its shape, size and position match the trapezoidal shear key 5, and is used to accommodate the trapezoidal shear key 5 during installation.

[0049] In practical implementation, to achieve stable and symmetrical force transmission, such as Figure 7 As shown, two trapezoidal shear keys 5 are respectively provided on two opposite sides of the column end plate 2, that is, four are provided in total. Simultaneously, the two opposite trapezoidal shear keys 5 have bearing inclined surfaces that slope inwards towards each other, with an inclination angle of 5° to 10°. This inclined surface design allows the bearing inclined surfaces of the trapezoidal shear keys 5 to decompose the horizontal shear force into a normal clamping force and a tangential force along the inclined surface when transmitting horizontal shear force, thereby enhancing node stability and generating a self-resetting tendency.

[0050] To facilitate installation and ensure smooth engagement between the shear key and the shear groove, the width of the shear groove 6 has a preset assembly gap, such as 2mm, between it and the thickness of the trapezoidal shear key 5 after assembly.

[0051] In some embodiments, to avoid adverse stress coupling between the bolt 8 and the shear key 5 during the sliding process, the distance between the center of the trapezoidal shear key 5 and the center of the elongated hole 7 is greater than 20mm, ensuring that the functions of each component are clear and the force path is well-defined.

[0052] In some embodiments, the bearing inclined surface of the trapezoidal shear key 5 and the corresponding contact area of ​​the shear groove 6 are subjected to surface hardening treatment. Specifically, the surface hardening treatment is a quenching treatment, and the hardness after treatment is HRC45-50, so as to effectively improve its wear resistance and fatigue resistance.

[0053] The integrated design method for skylight frames and roof trusses in large-span building structures provided in this application combines the skylight frames and roof trusses into a single, load-bearing composite truss. This changes the force transmission path of traditional separate designs and utilizes dedicated hinged sliding nodes to achieve a unified approach to reliable force transmission and temperature deformation release. This method not only fundamentally eliminates secondary internal forces and stress concentrations caused by deformation incoordination and temperature effects, but also reduces the axial force of the roof truss's upper chord, increases mid-span stiffness, and effectively reduces steel consumption, resulting in economic benefits.

[0054] In the description of this application, it should be noted that the terms "vertical", "up", "down", "horizontal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0055] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0056] Finally, it should be noted that the above descriptions are merely preferred embodiments of this application and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for the integrated design of skylight frames and roof trusses in large-span building structures, characterized in that, Includes the following steps: A) Establish the finite element model of the roof truss and the finite element model of the skylight frame; B) Combine the finite element model of the skylight frame with the finite element model of the roof truss to form a unified finite element model that is structurally coordinated under stress; C) In the overall finite element model, a hinged sliding node is set at the connection between the skylight frame and the roof truss. The hinged sliding node is set to transmit only axial force and shear force, while releasing bending moment constraints and temperature deformation constraints along the transverse direction of the roof truss. D) Perform structural analysis on the overall finite element model after applying the load to obtain the internal force analysis results of the model; E) Based on the internal force analysis results, optimize the design of the components within the combined truss area formed by the roof truss and skylight frame.

2. The integrated design method for skylight frames and roof trusses in large-span building structures according to claim 1, characterized in that, The internal force analysis results include, but are not limited to, component axial force, shear force, bending moment, stress, and displacement data.

3. The integrated design method for skylight frames and roof trusses in large-span building structures according to claim 1, characterized in that, Step A specifically includes: establishing the finite element model of the roof truss based on the national standard roof truss drawing set, and establishing the finite element model of the skylight frame based on the national standard skylight frame drawing set.

4. The integrated design method for skylight frames and roof trusses in large-span building structures according to claim 1, characterized in that, The combined truss region is defined as the structural region enclosed in the vertical plane by the skylight frame and the roof truss portion spanning below it; and the optimization design in step E includes at least the selection of cross-sections for the roof truss and skylight frame components within the combined truss region.

5. The integrated design method for skylight frames and roof trusses in large-span building structures according to claim 1, characterized in that, Based on the results of the optimization design, the performance parameters required to realize the articulated sliding node are determined.

6. The integrated design method for skylight frames and roof trusses in large-span building structures according to claim 5, characterized in that, The performance parameters include the required sliding amount of the hinged sliding node, which is determined based on the thermal expansion deformation calculation formula of the roof truss ΔL1=α·L1·ΔT; where α is the linear expansion coefficient of the roof truss, L1 is the span of the roof truss, and ΔT is the maximum annual temperature difference in the region where the large-span building structure is located.

7. The integrated design method for skylight frames and roof trusses in large-span building structures according to claim 5, characterized in that, The performance parameters also include the design value of the shear bearing capacity and the coefficient of sliding friction of the hinged sliding node.

8. The integrated design method for skylight frames and roof trusses in large-span building structures according to any one of claims 1 to 7, wherein the hinged sliding node includes a sliding component and a shear-resistant component, and the bottom end of the skylight frame column is provided with a column end plate, wherein: The sliding component includes: At least one PTFE plate is disposed between the column end plate and the upper chord of the roof truss; An oblong hole is formed on the end plate of the column, and its length direction is consistent with the transverse direction of the upper chord of the roof truss; Bolts, passing through the elongated holes, are used to slidably connect the column end plate to the upper chord of the roof truss; The shear-resistant component includes: At least one trapezoidal shear key is fixed to the upper surface of the upper chord of the roof truss; A shear groove matching the trapezoidal shear key is formed on the side of the column end plate and is used to accommodate the trapezoidal shear key.

9. The integrated design method for skylight frames and roof trusses in large-span building structures according to claim 8, characterized in that, The trapezoidal shear keys are arranged in pairs on two opposite sides of the column end plate. Each pair of two trapezoidal shear keys has a bearing slope that inclines inward toward each other, and the inclination angle of the bearing slope is 5° to 10°.

10. The integrated design method for skylight frames and roof trusses in large-span building structures according to claim 8, characterized in that, The length L2 of the oblong hole satisfies the formula: L2≥2R+ΔL2; where R is the radius of the bolt and ΔL2 is the maximum thermal expansion deformation of the roof truss under the design conditions.

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