An adjustable modular steel girder and method of designing the same

Abstract

This invention relates to the field of bridge steel guide beam technology, specifically to an adjustable modular steel guide beam and its design method. An adjustable modular steel guide beam includes two main beams, a left and a right, extending longitudinally along the bridge and arranged parallel to each other. Each main beam is composed of several segments spliced ​​end-to-end, including connecting segments, standard segments, nose segments, and front segments. An independent adjustment segment is also provided on either the left or right main beam, allowing the two main beams to have unequal lengths by setting the adjustment segment only on a single main beam. Several transverse trusses arranged at intervals along the longitudinal direction connect the two main beams, with each transverse truss detachably connected to both main beams at its ends. This invention achieves asymmetrical adjustment of the lengths of the left and right main beams by setting independent adjustment segments, ensuring that the guide beams on both sides are simultaneously mounted on the pier under skew conditions.

Description

Technical Field

[0001] This invention relates to the field of bridge steel guide beam technology, specifically to an adjustable modular steel guide beam and its design method. Background Technology

[0002] When long-span steel box girders cross existing railways, highways, or waterways, the incremental launching method is often used for erection. In this method, the steel box girder is assembled and welded in sections on an assembly platform on one side of the bridge site, and then pushed and slid along the longitudinal direction of the bridge section by section until it is finally placed on the permanent pier. To improve the stress state at the front end of the steel box girder during the incremental launching process and to avoid excessive cantilever length of the main girder leading to deflection or overturning at the front end, a temporary auxiliary structure, a steel guide beam, is usually added to the front end of the steel box girder in engineering practice.

[0003] A steel guide beam is generally composed of two parallel and symmetrically arranged main beams. The two main beams are fixed to the corresponding positions of the stiffening ribs on the web or bottom plate of the steel box girder. Their longitudinal length is usually 0.6 to 0.8 times the main span. Their bending stiffness is much smaller than that of the main beam, but sufficient to bear the self-weight and construction load in the cantilever state. By setting temporary supports at the front end of the guide beam, the cantilever span is decomposed into a multi-span continuous beam stress mode, thereby significantly reducing the maximum bending moment and shear force at the root of the main beam.

[0004] However, during construction, there are often situations where the bridge axis is oblique to the obstacle it spans. In this case, the arrangement axis of the temporary support at the front end of the steel guide beam is oblique to the bridge axis, resulting in unequal distances between the two main beams and the temporary support. Under the condition that the jacking stroke is the same, the guide beam that reaches the support first has been put on the support and is under force, while the guide beam on the other side has not yet reached the corresponding support, resulting in the guide beams on both sides not being able to be put on the support at the same time. Summary of the Invention

[0005] To address the shortcomings of existing steel guide beams that cannot be synchronously mounted on piers under skewed conditions, this invention proposes an adjustable modular steel guide beam and its design method.

[0006] In a first aspect, the present invention provides an adjustable modular steel guide beam, comprising a main beam and a transverse truss. The main beam includes two beams, one on the left and one on the right, extending longitudinally along the bridge and arranged parallel to each other. Each main beam includes a connecting section, a standard section, a nose section, and a front section connected sequentially. The connecting section connects the entire steel guide beam to the steel box girder. An adjusting section is located between the standard section and the nose section. The lengths of the connecting section, standard section, nose section, and front section of the two main beams are equal, but the lengths of the two main beams are made unequal by setting an adjusting section on a single main beam. The transverse truss connects the two main beams, and several transverse trusses are arranged at intervals along the longitudinal direction. Each transverse truss has two ends detachably connected to two of the main beams.

[0007] Preferably, multiple standard sections are provided, and the total length of the steel guide beam is adjusted by changing the number and module of the standard sections. This allows for flexible adjustment of the total length of the guide beam according to different bridge spans, improving versatility.

[0008] Preferably, each of the transverse trusses is composed of several transverse segments spliced ​​end to end. The spacing between the left and right main beams is adjusted by adjusting the number and module of the transverse segments, thereby adjusting the total width of the steel guide beam. This achieves modular adjustment in the width direction.

[0009] Preferably, a transverse brace is provided at the connection between the transverse truss and the longer main beam. This transverse brace can enhance the lateral stability of the longer single-sided main beam and avoid eccentric deformation caused by the difference in length between the two sides.

[0010] Preferably, adjacent main beam segments are connected by connecting plates and bolts. The bolted connection method facilitates quick on-site assembly and disassembly and allows for reuse.

[0011] Furthermore, the connecting plate includes an upper connecting plate, a web connecting plate, and a lower connecting plate. The upper connecting plate and the web connecting plate are provided with bolt holes, while the lower connecting plate is not provided with bolt holes. The lower connecting plate connects the bottom surfaces of two adjacent segments by welding.

[0012] Preferably, the connecting section, standard section, adjusting section, and nose bridge section are all welded from thin steel plates into an I-shaped cross-section. The cross-sectional heights of the connecting section, standard section, and adjusting section remain constant, while the cross-sectional height of the nose bridge section monotonically varies along its length. This cross-sectional shape has high bending stiffness and lightweight characteristics, making it suitable for withstanding bending moments and shear forces.

[0013] Preferably, the front section is a truss welded from steel sections, and the cross-sectional height of the front section remains constant and is equal to the minimum cross-sectional height of the bridge section.

[0014] Preferably, the transverse connecting segments are welded from rectangular square steel pipes, and adjacent transverse connecting segments are connected to each other and to the main beam and the transverse connecting segments by flange plates and bolts.

[0015] Secondly, the present invention provides a design method for a steel guide beam, used to design the aforementioned adjustable modular steel guide beam, comprising the following steps:

[0016] S1: Based on the design span of the bridge, determine the length of the main beam. Subtract the length of the connecting section, nose section, and front section from the length of the steel guide beam to obtain the required standard section length. Select an appropriate standard section module, divide the calculated standard section length by the standard section module, and round up to obtain the number of standard sections to be installed. S2: Based on the design width of the bridge, determine the optional width range of the cross truss, select an appropriate cross segment module, divide the width range of the cross truss by the cross segment module to obtain the range of the number of cross segments to be installed, and take the integer part as the number of cross segments to be installed. S3: The acute angle between the bridge's design axis and the temporary pier layout axis is the skew angle α. The width of the steel guide beam is obtained by adding the distance between the fixed ends of the cross truss and the axis of the main beam to the width of the cross truss determined in S2. The width of the steel guide beam is then divided by tanα to calculate the required length difference between the two main beams. The adjustment section module closest to and greater than or equal to this distance difference is then selected as the length of the adjustment section. The design is now complete.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention provides an adjustable modular steel guide beam, which splits two main beams into modular segments, each consisting of a connecting segment, a standard segment, a nose segment, and a front segment spliced ​​together end to end, and sets an adjustment segment on a single main beam, thereby achieving asymmetrical adjustment of the length of the two main beams, thus ensuring that the main beams on both sides can be simultaneously mounted on the pier under skew conditions.

[0018] 2. The present invention provides a design method for an adjustable modular steel guide beam. The total length of the steel guide beam is adjusted by calculating the number of standard sections to be installed based on the bridge span, and the total width of the steel guide beam is adjusted by calculating the number of cross truss segments to be installed based on the bridge width. This achieves rapid matching of the overall dimensions of the steel guide beam with the main parameters of the bridge. Furthermore, the length of the adjustable section is calculated using the spacing between the main beams and the skew angle, so that the length difference between the left and right main beams is precisely matched with the distance difference from the front end of the two main beams to the temporary support. Attached Figure Description

[0019] Figure 1 This is a structural diagram of an adjustable modular steel guide beam.

[0020] Figure 2 for Figure 1 A magnified view of a portion of the image.

[0021] Figure 3 This is an exploded view of an adjustable modular steel guide beam.

[0022] Figure 4 for Figure 3 A magnified view of a portion of the image.

[0023] Figure 5 A plan view showing the usage state of an adjustable modular steel guide beam.

[0024] Figure 6 for Figure 5 Section 1-1 in the diagram.

[0025] Figure 7 for Figure 6 A magnified view of a portion of the image.

[0026] The markings in the diagram are: 1-Main beam, 11-Connecting section, 12-Standard section, 13-Nose bridge section, 14-Front section, 15-Adjusting section, 2-Horizontal truss, 21-Horizontal connecting segment, 22-Horizontal brace, 23-Flange plate, 3-Connecting plate, 31-Upper connecting plate, 32-Web plate connecting plate, 33-Lower connecting plate, 4-Steel box girder, 5-Temporary support. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0028] Example 1 like Figures 1 to 7 As shown, the present invention provides an adjustable modular steel guide beam, which mainly includes a main beam 1 and a transverse truss 2.

[0029] The main beam 1 includes two sections, one on the left and one on the right, which extend longitudinally along the bridge and are arranged parallel to each other. The main beam 1 is composed of several segments spliced ​​together longitudinally. These segments sequentially include a connecting section 11, a standard section 12, a nose section 13, and a front section 14. The connecting section 11 connects to the steel box girder 4. The connecting section 11 and the standard section 12 have the same height, but the connecting section 11 is greater than the height of the front section 14. The height of the nose section 13 transitions from the standard section 12 to the front section 14. Specifically, in this embodiment, an adjusting section 15 is provided on the right main beam 1, positioned between the standard section 12 and the nose section 13, so that the length of the right main beam 1 is greater than the length of the left main beam 1.

[0030] The transverse truss 2 is connected between the two main beams 1. The transverse trusses 2 are arranged at intervals along the longitudinal direction of the bridge, and a total of 3 transverse trusses 2 are provided. The transverse truss 2 connected to the nose section 13 is less tall than the other two. The two ends of each transverse truss 2 are detachably connected to the two main beams 1 respectively.

[0031] Specifically, in this embodiment, one standard segment 12 is provided according to the length of the bridge, and the length module is selected as 3m.

[0032] Specifically, each of the transverse trusses 2 is composed of several transverse segments 21 spliced ​​together end to end. In this embodiment, there are two transverse segments 21 according to the width of the bridge, and the length module of a single transverse segment 21 is 4m.

[0033] Specifically, such as Figure 3As shown, a cross brace 22 is also provided at the connection between the farthest cross truss 2 and the right main beam 1. One end of the cross brace 22 is fixedly connected to the end of the cross truss 2, and the other end is fixedly connected to the nose section 13 of the right main beam 1.

[0034] Specifically, such as Figure 4 As shown, adjacent main beam segments 1 are connected by connecting plates 3 and bolts. Figure 5 As shown, the connecting plate 3 includes an upper connecting plate 31, a web connecting plate 32, and a lower connecting plate 33. The upper connecting plate 31 and the web connecting plate 32 are provided with bolt holes for high-strength bolts to achieve a fixed connection. The lower connecting plate 33 is not provided with bolt holes and is connected to the bottom of adjacent segments by welding.

[0035] Specifically, the connecting section 11, standard section 12, adjusting section 15, and nose bridge section 13 are all welded from thin steel plates into an I-shaped cross-section. The I-shaped cross-section consists of an upper flange plate, a lower flange plate, and a web plate, possessing high bending stiffness and shear resistance while being lightweight, making it suitable for withstanding bending moments and shear forces during jacking construction. The height of the I-shaped cross-section is determined based on stress calculations. The front section 14 is a truss welded from channel steel and I-beams; due to the absence of a web plate, it is even lighter and suitable for the cantilever end of a steel guide beam.

[0036] Specifically, such as Figure 6 and Figure 7 As shown, the transverse connecting segments 21 are welded from rectangular square steel tubes, and adjacent transverse connecting segments 21 are connected by flange plates 23 and bolts. Rectangular square steel tubes have good torsional resistance and load-bearing capacity, making them suitable as the main load-bearing components of the transverse truss. Flange plates 23 are welded to the ends of the transverse connecting segments 21, and bolt holes are provided on the flange plates 23. The flange plates 23 of adjacent transverse connecting segments 21 are fixedly connected by bolts.

[0037] In some implementations, the module and quantity of standard section 12, adjustment section 15 and cross section 21 can be determined according to the specific design dimensions of the bridge.

[0038] Example 2 The present invention also provides a design method for a steel guide beam, comprising the following steps: S1: Based on the bridge's design span, determine the length of the main beam 1. Subtract the lengths of the connecting section 11, nose section 13, and front section 14 from the length of the main beam 1 to obtain the required length of the standard section 12. Select a suitable module for the standard section 12, divide the calculated length of the standard section 12 by the module, and round up to obtain the number of standard sections 12 to be installed. Specifically, the total length of the steel guide beam is 0.6 to 0.8 times the maximum span of the bridge; in this embodiment, it is 0.6 times. The lengths of the connecting section 11, nose section 13, and front section 14 are prefabricated components and are all known fixed values. The standard section 12 adopts a uniform length module of 2m or 3m. Divide the calculated total length of the standard section 12 by the module and round up to determine the number of standard sections 12 to be installed. Rounding up ensures that the actual assembled guide beam length is not less than the design required length, guaranteeing construction safety.

[0039] S2: Based on the design width of the bridge, determine the optional width range of the transverse truss 2, select a suitable module for the transverse segment 21, divide the width range of the transverse truss 2 by the module of the transverse segment 21 to obtain the range of the number of transverse segments 21 to be installed, and take the integer part as the number of transverse segments 21 to be installed; specifically, the width of the transverse truss 2 is usually matched with the width of the steel box girder 4, generally taken as 0.8 to 1.0 times the width of the bottom plate of the steel box girder 4. The transverse segments 21 adopt a uniform length module, for example, the length of each transverse segment 21 is 3m or 4m. Select a suitable module for the transverse segment 21 so that the range of the number of transverse segments 21 to be installed contains an integer, then the integer obtained is the number of transverse segments 21 to be installed, and the product of the integer obtained and the module is the width of the steel guide beam.

[0040] S3: As Figure 5 As shown, the acute angle between the bridge's design axis and the arrangement axis of the temporary pier 5 is the skew angle α. The width of the steel guide beam (i.e., the axial distance between the two main beams 1) is obtained by adding the width of the transverse truss 2 determined in S2 to the distance between the fixed ends of the transverse truss 2 and the axis of the main beam 1. The width of the steel guide beam is divided by tanα to calculate the required length difference between the two main beams 1. Then, the module of the adjustment section 15 that is closest to and greater than or equal to this distance difference is selected as the length of the adjustment section 15. The design is now complete.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An adjustable modular steel guide beam, characterized in that, include: The main beam (1) includes two main beams (1), which extend along the longitudinal direction of the bridge and are arranged parallel to each other. The main beam (1) includes a connecting section (11), a standard section (12), a nose section (13) and a front section (14) connected in sequence. An adjustment section (15) is set between the standard section (12) and the nose section (13). The lengths of the connecting section (11), standard section (12), nose section (13) and front section (14) of the two main beams (1) are equal. The lengths of the two main beams (1) are made unequal by setting an adjustment section (15) on a single main beam (1). A transverse truss (2) is connected between two main beams (1). Several transverse trusses (2) are arranged at intervals along the longitudinal direction of the bridge. The two ends of each transverse truss (2) are detachably connected to the two main beams (1).

2. The adjustable modular steel guide beam according to claim 1, characterized in that, The total length of the steel guide beam is adjusted by adjusting the number and module of the standard section (12).

3. The adjustable modular steel guide beam according to claim 1, characterized in that, Each cross truss (2) includes several cross segments (21). The width of the steel guide beam is adjusted by adjusting the number and module of the cross segments (21) to adjust the spacing between the two main beams (1).

4. An adjustable modular steel guide beam according to claim 1, characterized in that, A cross brace (22) is provided at the connection between the cross truss (2) and the longer main beam (1).

5. An adjustable modular steel guide beam according to claim 1, characterized in that, The two adjacent segments of the main beam (1) are connected by connecting plates (3) and bolts.

6. An adjustable modular steel guide beam according to claim 5, characterized in that, The connecting plate (3) includes an upper connecting plate (31), a web connecting plate (32) and a lower connecting plate (33). The upper connecting plate (31) and the web connecting plate (32) are provided with bolt holes, while the lower connecting plate (33) is not provided with bolt holes. The lower connecting plate (33) connects the bottom surfaces of two adjacent segments by welding.

7. An adjustable modular steel guide beam according to claim 1, characterized in that, The connecting section (11), standard section (12), bridge section (13) and adjustment section (15) are all I-shaped sections. The height of the connecting section (11), standard section (12) and adjustment section (15) remains unchanged, while the height of the bridge section (13) changes monotonically along its length.

8. An adjustable modular steel guide beam according to claim 1, characterized in that, The front section (14) is a truss made of welded steel sections. The cross-sectional height of the front section (14) remains unchanged and is equal to the minimum cross-sectional height of the nose section (13).

9. An adjustable modular steel guide beam according to claim 1, characterized in that, Adjacent cross sections (21) are connected to each other and the main beam (1) is connected to the cross section (21) by flanges (23) and bolts.

10. A design method for a steel guide beam, characterized in that, The method for designing an adjustable modular steel guide beam as described in any one of claims 1 to 9 includes the following steps: S1: Based on the design span of the bridge, determine the length of the main beam (1), subtract the length of the connecting section (11), the nose section (13), and the front section (14) from the length of the main beam (1) to obtain the required length of the standard section (12), select the module of the standard section (12), divide the calculated length of the standard section (12) by the module of the standard section (12), and round up to obtain the number of standard sections (12) to be installed; S2: Based on the design width of the bridge, determine the width range of the cross truss (2), select the module of the cross segment (21), divide the width range of the cross truss (2) by the module of the cross segment (21) to obtain the range of the number of cross segments (21) to be installed, and take the integer part as the number of cross segments (21) to be installed. S3: The acute angle between the design axis of the bridge and the arrangement axis of the temporary pier (5) is the oblique angle α. The width of the steel guide beam is obtained by adding the width of the cross truss (2) determined in S2 to the distance between the fixed ends of the cross truss (2) and the axis of the main beam (1). The width of the steel guide beam is divided by tanα to calculate the required length difference between the two main beams (1). Then, the module of the adjustment section (15) that is closest to and greater than or equal to the distance difference is selected as the length of the adjustment section (15). The design is now complete.

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