Ultrahigh-strength steel small beam and mounting method thereof

Abstract

The invention discloses an ultrahigh-strength steel small beam which comprises a main beam and secondary beams, the main beam is connected with a plurality of secondary beams through bolts, the bolts are located on the two sides of the intersecting center line of the main beam and the secondary beams, and the minimum upper yield strength of the secondary beams is 355 Mpa. The super-strong small beam is better in bending resistance, lighter in weight and smaller in welding length and size, and the welding process is easy to implement. The scheme can realize the lightweight design of the blocks, and can reduce the overall investment of the ocean platform.

Description

Technical Field

[0001] The invention relates to the technical field of offshore petroleum engineering, and in particular to an ultra-high-strength steel beam and a mounting method thereof. Background Art

[0002] The offshore platform module structure is a space frame structure composed of I-beams and round tube structures. The module deck is composed of deck plates, main beams and secondary beams, which are used to support the operating weight of the upper facilities. The gravity load acting on the deck plate is transmitted to the secondary beams, which are then transferred to the main beams, and finally transferred to the interlayer round tube support columns or diagonal braces by the main beams. Among them, the secondary beams account for a large proportion of the module weight, about 30% of the weight of the main structure. During the construction process, the welding workload of the secondary beams is huge.

[0003] According to the current "General Material Specifications for Offshore Fixed Platforms in China", the secondary beams currently used in the modular structure adopt the GB / T 34103-2017 standard, which mainly covers the following three sizes: H350X175X7X11, H300X150X6.5X9, and H400X200X8X13. Currently, the secondary beams of the modular structure use low-strength profiles with a yield strength of 235Mpa.

[0004] Therefore, there is an urgent need for an ultra-high-strength steel beam. Summary of the invention

[0005] On one hand, the present invention provides an ultra-high-strength steel beam, which uses a high-strength beam instead of a low-strength beam as a secondary beam, and realizes a lightweight design of a block structure by optimizing material selection, uniform design, structural analysis, and layout optimization, shortening the platform construction period, thereby reducing the investment in the offshore platform. On the other hand, the present invention provides an installation method for an ultra-high-strength steel beam.

[0006] A first aspect of the present invention provides an ultra-high strength steel beam, comprising a main beam and a secondary beam, wherein the main beam is connected to a plurality of secondary beams by bolts, and the bolts are located on both sides of the center line of the intersection of the main beam and the secondary beams, wherein the minimum upper yield strength of the secondary beam is 355 MPa.

[0007] The ultra-high strength steel beams, preferably, have a spacing of 1.1-1.2 m between the secondary beams.

[0008] The ultra-high strength steel secondary beam preferably has a tensile strength between 490 and 630 MPa.

[0009] A second aspect of the present invention provides a method for installing the ultra-high-strength steel beam, comprising the following steps:

[0010] The plurality of secondary beams are fixed to the main beam by bolts.

[0011] In the installation method of the ultra-high-strength steel beams, preferably, the spacing between the secondary beams is 1.1-1.2m.

[0012] The beneficial effects are:

[0013] Compared with traditional low-strength beams, the high-strength beams of the present application have better bending resistance, and their yield strength is 1.511 times that of the low-strength beams. Under the same uniformly distributed force at the same span, the bending stress is 0.624 times that of the low-strength beams, and the bending deflection of the beam is 0.534 times that of the low-strength beams.

[0014] In the past, the spacing between secondary beams of the blocks was usually 0.9m-1.0m. Due to the increased strength of the high-strength small beams in this application, the spacing between secondary beams can reach 1.1-1.2m under the same uniformly distributed force. Compared with low-strength small beams, it can save about 20% of the steel used in the secondary beams, reduce the weight of the structure, and reduce the workload including welding.

[0015] Different from traditional welding connections, the present application involves a main beam and a secondary beam structure connected by bolts, and the bolts are located on both sides of the center line of the intersection of the main beam and the secondary beam to facilitate disassembly and replacement.

[0016] The ultra-strong beam of the present application has better bending resistance, lighter weight, smaller welding length and volume, and easier welding process. The solution can realize lightweight design of modules and reduce the overall investment of offshore platforms. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a three-dimensional diagram of the connection structure between the deck main beam and the secondary beam;

[0018] Figure 2 yes Figure 1 The front view of the connection structure between the deck main beam and the secondary beam;

[0019] Figure 3 yes Figure 1 A top view of the connection structure between the deck main beam and the secondary beam;

[0020] Figure 4 It is a schematic diagram of the structure of the I-beam in Example 4.

[0021] In the figure:

[0022] 1. Main beam; 2. Secondary beam; 3. Bolts. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] In the description of the present invention, it should be noted that the terms "upper" and "lower" etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the system or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0025] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] The present invention provides an ultra-high strength steel beam, comprising a main beam and a secondary beam, wherein the main beam is connected to a plurality of secondary beams by bolts, and the bolts are located on both sides of the center line of the intersection of the main beam and the secondary beam, wherein the minimum upper yield strength of the secondary beam is 355 MPa. The ultra-high strength beam of the present invention has better bending resistance, lighter weight, smaller welding length and volume, and easy implementation of welding process. The scheme can realize lightweight design of modules and reduce the overall investment of offshore platforms.

[0027] The entire technical process is explained in detail below using an ultra-high-strength steel beam as an example.

[0028] Example 1

[0029] like Figure 1 , Figure 2 and Figure 3 As shown, an ultra-high strength steel beam includes a main beam 1 and a secondary beam 2. The main beam 1 is connected to multiple secondary beams 2 by bolts 3, and the bolts 3 are located on both sides of the intersection center line of the main beam 1 and the secondary beam 2, wherein the minimum upper yield strength of the secondary beam 2 is 355Mpa.

[0030] The material of secondary beam 2 is mainly based on GB / T 34103-2017 standard, which is suitable for manufacturing hot-rolled H-shaped steel with flange thickness not exceeding 50mm for marine engineering structures. The chemical composition includes: C≤0.18, Si≤0.50, 0.9≤Mn≤1.60, P≤0.030, S≤0.030, and the rest are alloy elements (AH36). The heat treatment method of hot rolling is adopted, the carbon equivalent and Pcm CEV≤0.38, the minimum upper yield strength is 355MPa, the tensile strength is between 490 and 630Mpa, and the section elongation is ≥21%. The specification standard is GB / T11263.

[0031] Among them, the secondary beam 2 includes the following specifications: H300*150, H350*175, H400*200, which are common specifications and profiles, and can be supplied by many steel mills, and there is a certain amount of spot in the market. The foundation structure can be mass-produced, with standard dimensions, and can adapt to most standardized jacket designs in Bohai, shortening the design cycle and reducing the difficulty of construction.

[0032] The spacing between the secondary beams 2 is 1.1-1.2 m. As the strength of the high-strength beam is increased, compared with the low-strength beam, the steel consumption of the secondary beam can be saved by about 20%, the weight of the structure can be reduced, and the welding workload can be reduced.

[0033] Example 2

[0034] A second aspect of the present invention provides a method for installing the ultra-high-strength steel beam, comprising the following steps:

[0035] The plurality of secondary beams are fixed to the main beam by bolts.

[0036] In the installation method of the ultra-high-strength steel beams, preferably, the spacing between the secondary beams is 1.1-1.2m.

[0037] Example 3

[0038] In this example, the main beam size is H1800×650×45×50, and the secondary beam size is H300×150×6.5×9.

[0039] Taking a certain model of standardized platform in Bohai as an example, by using the high-strength small beam of Example 1 instead of the low-strength small beam, the block weight can be optimized by 20-100t, the weld length can be reduced by 128-507m, and the reduction of the steel consumption of the secondary beam structure alone can save investment of 58,000-284,000 yuan.

[0040] Example 4

[0041] like Figure 4 As shown in the figure, B is the width of the I-beam flange, H is the height of the I-beam web, t 1 is the wing thickness, t 2is the web thickness. I-beam is expressed as H×B×t 1 ×t 2 Taking a span of 5 meters, a high-strength small beam with a secondary beam of H300X150X6.5X9, and a low-strength small beam with a secondary beam of H350X175X7X11 as an example, the cross-sectional area, moment of inertia, and bending modulus are calculated by formula (1), formula (2), and formula (3) respectively:

[0042] S=2B×t 2 +(H-2t 2 )×t 1 +(4-π)×r 2 (1)

[0043] in,

[0044] B is the width of the I-beam flange;

[0045] H is the height of the I-beam web;

[0046] t 1 is the wing thickness;

[0047] t 2 is the web thickness;

[0048] r is the radius of the 1 / 4 arc at the intersection of the web and the flange.

[0049]

[0050] in,

[0051] I x is the moment of inertia;

[0052] B is the width of the I-beam flange;

[0053] H is the height of the I-beam web;

[0054] t 1 is the wing thickness;

[0055] t 2 is the web thickness;

[0056] r is the radius of the 1 / 4 arc at the intersection of the web and the flange.

[0057]

[0058] in,

[0059] W x is the flexural modulus;

[0060] I x is the moment of inertia;

[0061] H is the height of the I-beam web.

[0062] Table 1 Comparison of cross-sectional parameters between Q355 high-strength beam and Q235 low-strength beam

[0063]

[0064] Table 2 Optimized layout of high-strength beams and low-strength beams

[0065]

[0066] Table 3 Size and specifications of high-strength beams

[0067]

[0068] As shown in Table 1, the high-strength beam with a secondary beam of H300X150X6.5X9 is compared with the low-strength beam with a secondary beam of H350X175X7X11:

[0069] 1. Lighter weight: The high-strength small beam with the same length and the secondary beam being H300X150X6.5X9 is about 25.6% lighter than the low-strength steel beam with the secondary beam being H350X175X7X11;

[0070] 2. Smaller weld length and volume: The weld length is calculated based on the length of the upper and lower flanges and webs at both ends of each beam, and the weld volume is calculated based on the 45° groove penetration weld of the flange and the foot fill welds on both sides of the web. The weld length of the high-strength beam is reduced by 14.3% and the weld volume is reduced by 37.4%.

[0071] As shown in Table 3, the high-strength beam with a secondary beam of H300X150X6.5X9 is compared with the low-strength beam with a secondary beam of H350X175X7X11:

[0072] Better bending resistance: Under the same uniformly distributed force at the same span, the bending stress of the high-strength beam is 0.624 times that of the low-strength beam, and the bending deflection of the beam is 0.534 times that of the low-strength beam.

[0073] In summary, the welding and inspection processes of the high-strength small beam with a secondary beam of H300X150X6.5X9 and the low-strength small beam with a secondary beam of H350X175X7X11 are consistent and easy to implement.

[0074] Table 4 Weight reduction, weld length and volume optimization effects achieved by using high / low strength beams for standardized platforms of different sizes and types

[0075]

[0076] In summary, the high-strength small beam with a secondary beam of H300X150X6.5X9 has better bending resistance, lighter weight, smaller welding length and volume, and easier welding process. The solution can achieve lightweight design of modules and reduce the overall investment of offshore platforms.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An ultra-high strength steel beam, characterized in that: It includes a main beam and a secondary beam, wherein the main beam is connected to a plurality of secondary beams by bolts, and the bolts are located on both sides of the intersection center line of the main beam and the secondary beams, wherein the minimum upper yield strength of the secondary beams is 355Mpa.

2. The ultra-high strength steel beam according to claim 1, characterized in that: The distance between the secondary beams is 1.1-1.2 m.

3. The ultra-high strength steel beam according to claim 2, characterized in that: The tensile strength of the secondary beam is between 490 and 630 MPa.

4. A method for installing an ultra-high strength steel beam as claimed in any one of claims 1 to 3, characterized in that: The method comprises the following steps: fixing a plurality of secondary beams to the main beam by means of bolts.

5. The method for installing the ultra-high strength steel beam according to claim 4, characterized in that: The distance between the secondary beams is 1.1-1.2 m.

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