Lightweight high-strength anti-fatigue K-shaped cast steel joint

Abstract

The invention provides a lightweight high-strength anti-fatigue K-shaped cast steel joint, and belongs to the technical field of building structures. The steel pipe specifically comprises a group of circular main steel pipes and two groups of circular branch steel pipes, spaces in the main circular pipes and the branch circular pipes are communicated with each other, the pipe diameter-thickness ratio of the main circular pipes is 12.17 and 24.33, in the space of the main circular pipes, the central axes of the two branch circular pipes intersect and are located on the same plane, the first branch circular pipe is a tension branch pipe, the diameter-thickness ratio of the first branch circular pipe is 14.78 and 8.58, and the included angle between the first branch circular pipe and the main circular pipe is 125 degrees. The second branch round pipe is a pressed branch pipe, the diameter-thickness ratio is 8.58, the included angle between the second branch round pipe and the main round pipe is 55 degrees, the diameter-thickness ratio is 8.58, the second branch round pipe and the K-shaped cast steel joint are integrally formed through the overall pouring technology, and the pouring material is high-strength steel. According to a pipe truss structure, the high-strength cast steel joints are applied to the pipe truss, so that joint welding seams in a joint area are avoided, heat affected zones of the welding seams do not coincide, local residual stress and stress concentration are reduced, the static force and fatigue performance of the joints and even the whole structure is greatly improved, meanwhile, the thickness of steel pipes is optimized, and the dead weight of the joints is reduced; and high strength and good anti-fatigue performance are kept while the node is light in weight.

Description

Technical Field

[0001] This invention relates to the field of building structure technology, and in particular to a lightweight, high-strength, fatigue-resistant K-type cast steel joint. Background Technology

[0002] In current designs, the wall thickness of ordinary cast steel nodes is generally greater than that of the steel pipes they connect to, and their self-weight is also much greater than that of traditional welded nodes. This increase in structural construction costs is significant and greatly limits their widespread application. Furthermore, the current shape and internal cavity shape of cast steel nodes are designed by designers based on experience, merely reducing stress concentration through rounded corners. This fails to fully utilize the advantages of the casting and shaping freedom of cast steel nodes, resulting in problems such as significant differences in stress levels in different areas and unsmooth force flow. Because the experience-based design method is relatively conservative, there is considerable redundancy in the node strength and fatigue performance (especially in the cast steel material portion). Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a lightweight, high-strength, fatigue-resistant K-type cast steel joint.

[0004] To solve the above-mentioned technical problems, the present invention is implemented using the following technical solution:

[0005] A lightweight, high-strength, fatigue-resistant K-type cast steel node includes a set of circular main steel pipes and two sets of circular branch steel pipes. The internal spaces of the main pipes and branch pipes are interconnected. The K-type cast steel node is integrally cast using a casting technology and the casting material is high-strength steel.

[0006] As a preferred embodiment, the two sets of branch pipes are located on the same side of the main pipe, the central axes of the branch pipes are on the same plane and intersect in the inner cavity of the main pipe, the angle between the first branch pipe and the main pipe is 125°, the angle between the second branch pipe and the main pipe is 55°, and the closest distance between the outer surfaces of the first and second branch pipes is 40mm.

[0007] As a preferred technical solution, the outer diameter of the main circular pipe is 219mm, and the pipe wall thickness includes 9mm and 18mm. The wall thickness of the semi-circular pipe on the side of the main circular pipe without branch pipes is 9mm, the wall thickness of the main circular pipe outside the axis of the first branch pipe is 9mm, and the wall thickness of the semi-circular pipe at the intersection with the branch pipes is thickened to 18mm. The section with the increased thickness is perpendicular to the central axis of the main circular pipe, and the diameter-to-thickness ratio of the main circular pipe is 24.33 and 12.17.

[0008] As a preferred technical solution, the first branch pipe is a tension branch pipe with an outer diameter of 133mm and a wall thickness of 9mm and 15.5mm. The diameter-to-thickness ratio of the branch pipe is 14.78 and 8.58, and the thickness increase section is perpendicular to the central axis of the first branch pipe.

[0009] As a preferred technical solution, the second branch pipe is a pressure branch pipe with an outer diameter of 133mm and a wall thickness of 15.5mm, and the diameter-to-thickness ratio of the branch pipe is 8.58.

[0010] Compared with existing technologies, this invention reduces the self-weight of the node by finely optimizing the internal cavity of the node and actively finding the shape design. It develops a high-strength fatigue-resistant K-type cast steel node with reasonable stress distribution and light and beautiful shape, giving full play to the advantages of high-strength steel and cast steel nodes. Attached Figure Description

[0011] Figure 1 This is a three-dimensional view of the K-type cast steel node of the present invention;

[0012] Figure 2 for Figure 1 A cross-sectional view of the entire K-type cast steel node;

[0013] Figure 3 for Figure 1 Cross-sectional view of the main circular pipe of the K-type cast steel node;

[0014] Figure 4 for Figure 1 Cross-sectional view of the first circular pipe of the K-type cast steel node;

[0015] Figure 5 for Figure 1 Cross-sectional view of the second circular pipe of the K-type cast steel node;

[0016] Among them, 1. Main circular pipe; 2. First branch circular pipe; 3. Second branch circular pipe; 4. Thin-walled area of ​​main circular pipe; 5. Thickened area of ​​main circular pipe; 6. Thin-walled area of ​​first branch circular pipe; 7. Thickened area of ​​first branch circular pipe. Detailed Implementation

[0017] The present invention will now be described in more detail with reference to the schematic diagrams, which illustrate preferred embodiments of the invention. It should be understood that those skilled in the art can modify the invention described herein while still achieving the beneficial effects of the invention. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the invention.

[0018] In the description of this invention, it should be noted that the directional terms such as "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention 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. They should not be construed as limiting the specific protection scope of this invention.

[0019] Reference Figure 1 and Figure 2 This invention provides a lightweight, high-strength, fatigue-resistant K-type cast steel node, comprising a set of circular main steel pipes and two sets of circular branch steel pipes. The internal spaces of the main and branch pipes are interconnected. This K-type cast steel node is integrally formed using a cast-in-place technique, and the casting material is national standard Q460 high-strength steel. Specifically, the two sets of branch pipes are located on the same side of the main pipe, with their central axes on the same plane and intersecting within the internal space of the main pipe. The node as a whole forms a "K" shape. The distance between the intersection point of the branch pipe central axes and the central axis of the main pipe is 35mm, and the distance between the intersection point and the central axis must be less than or equal to 0.25 times the outer diameter of the main pipe. The angle between the first and second branch pipes and the main pipe is 55°, and the adjustment range of each branch pipe can be maintained between 30° and 60°. The bottoms of the first and second round pipes should intersect the main round pipe separately, ensuring that the first and second round pipes have no overlapping parts. In the figure, the closest distance between the outer surfaces of the first and second round pipes is 40mm. It is necessary to ensure that this shortest distance is greater than or equal to the sum of the thickest wall thicknesses of the first and second round pipes.

[0020] Reference Figure 2 and Figure 3 The main circular pipe has a total length of 2.5m and an outer diameter of 219mm. The sum of the diameters of the first and second branch circular pipes should be less than or equal to twice the outer diameter of the main circular pipe, but greater than or equal to 0.2 times twice the outer diameter of the main circular pipe. The wall thickness of the main circular pipe includes 9mm and 18mm. The wall thickness of the semicircular pipe on the side of the main circular pipe without branch circular pipes is 9mm. The wall thickness of the main circular pipe outside the axis of the first branch circular pipe is 9mm. The wall thickness of the semicircular pipe at the intersection with the branch circular pipes is 18mm. The section where the thickness increases is perpendicular to the central axis of the main circular pipe. The diameter-to-thickness ratio of the main circular pipe is 24.33 and 12.17. The diameter-to-thickness ratio of the compression zone should not exceed 25.2, and the diameter-to-thickness ratio of the tension zone should not exceed 50.

[0021] Reference Figure 2 and Figure 4The first branch pipe has a central axis length of 785mm, an outer diameter of 133mm, and a wall thickness of 9mm and 15.5mm. The diameter-to-thickness ratio of this branch pipe is 14.78 and 8.58, and the ratio should not exceed 50. The thicker wall area should begin at the interface between the branch pipe and the main pipe, along the tensile direction of the branch pipe's central axis. The height of this thickened section is equal to the inner diameter cavity radius, and the increased thickness section is perpendicular to the central axis of the first branch pipe.

[0022] Reference Figure 2 and Figure 5 The second circular pipe is a pressure-bearing branch pipe. Its central axis length is 785mm, its outer diameter is 133mm, and its wall thickness is 15.5mm. The diameter-to-thickness ratio of this branch pipe is 8.58, and the diameter-to-thickness ratio should not be greater than 25.2.

[0023] It should be noted that, according to the technical specifications for cast steel joint applications, the minimum casting wall thickness for cast steel joints is 9mm. Therefore, considering practical manufacturing feasibility, the minimum wall thickness of the K-type cast steel joint of this invention is set to 9mm.

[0024] Furthermore, the lightweight and high-strength characteristics of the K-type cast steel node of this invention have been demonstrated through topology optimization and simulation calculations using finite element software. This invention targets tubular truss structures, applying high-strength cast steel nodes to avoid converging welds in the node region, ensuring that the heat-affected zones of each weld do not overlap, thereby reducing local residual stress and stress concentration, and significantly improving the fatigue performance of the node and even the entire structure.

[0025] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A lightweight, high-strength, fatigue-resistant K-type cast steel joint, characterized in that... It includes a set of circular main steel pipes and two sets of circular branch steel pipes. The internal spaces of the main and branch pipes are interconnected. This K-type cast steel node is integrally formed using a casting technology, and the casting material is high-strength steel.

2. The lightweight, high-strength, fatigue-resistant K-type cast steel joint according to claim 1, characterized in that, The two sets of branch pipes are located on the same side of the main pipe, and the central axes of the branch pipes are on the same plane and intersect in the inner cavity of the main pipe. The distance between the intersection point of the central axes of the branch pipes and the central axis of the main pipe is 35mm. The angle between the first branch pipe and the main pipe is 125°, the angle between the second branch pipe and the main pipe is 55°, and the closest distance between the surfaces of the first and second branch pipes is 40mm.

3. The lightweight, high-strength, fatigue-resistant K-type cast steel joint according to claim 1, characterized in that, The outer diameter of the main circular pipe is 219mm, and the wall thickness includes 9mm and 18mm. The wall thickness of the semi-circular pipe on the side of the main circular pipe without branch pipes is 9mm. The wall thickness of the main circular pipe outside the axis of the first branch pipe is 9mm. The wall thickness of the semi-circular pipe at the intersection with the branch pipes is thickened to 18mm. The thickening section is perpendicular to the central axis of the main circular pipe. The diameter-to-thickness ratio of the main circular pipe is 24.33 and 12.

17.

4. The lightweight, high-strength, fatigue-resistant K-type cast steel joint according to claim 2, characterized in that, The first branch pipe is a tension branch pipe with an outer diameter of 133mm and a wall thickness of 9mm and 15.5mm. The diameter-to-thickness ratio of the branch pipe is 14.78 and 8.58, and the thickness increase section is perpendicular to the central axis of the first branch pipe.

5. The lightweight, high-strength, fatigue-resistant K-type cast steel joint according to claim 2, characterized in that, The second branch pipe is a pressure branch pipe with an outer diameter of 133mm and a wall thickness of 15.5mm. The diameter-to-thickness ratio of this branch pipe is 8.58.

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