In-service steel pier anti-seismic toughness improving structure, construction method and application

Abstract

The invention relates to an in-service steel pier seismic toughness improving structure, a construction method and application, and belongs to the technical field of bridge seismic strengthening. The structure is mainly composed of an in-service steel pier, an existing bearing platform, a steel positioning ring plate, a contact longitudinal rib and a pier bottom bearing steel plate. Wherein the steel positioning ring plate is formed by welding two steel positioning semi-ring plates after positioning; the contact longitudinal rib is formed by welding a weakening rib plate and a contact end plate which are equal in thickness; the pier bottom bearing steel plate is formed by welding two pier bottom bearing steel splice plates after positioning, and is fixed in a reserved space in the existing bearing platform; the steel positioning ring plate is used for positioning and contacting the longitudinal rib and is welded and fixed on the in-service steel pier; a proper gap is reserved between the contact end plate of the contact longitudinal rib and the pier bottom bearing steel plate, so that a reasonable deformation space is guaranteed. The construction efficiency is high, on-site wet operation is not needed, the ductility is remarkably improved under the condition that the rigidity and strength of the bridge pier are not increased, the displacement tolerance after an earthquake is improved, and therefore the anti-seismic toughness of the bridge is enhanced.

Description

Technical Field

[0001] The present invention relates to a structure, construction method and application for enhancing the seismic resilience of in-service steel bridge piers, belonging to the technical field of bridge seismic strengthening. Background Art

[0002] Due to its excellent seismic performance and good plasticity, steel structures have been widely used in countries and regions with high seismic requirements. In addition, it also has the advantages of low carbon, light weight, environmental protection, strong plasticity and high industrialization, and is gradually becoming an important development direction in the field of civil engineering in China, promoting the transformation of the industry to an efficient and sustainable construction mode. As one of the important application forms of steel structures, steel bridge piers can be prefabricated in factories and quickly assembled at the construction site, significantly improving the construction efficiency and quality control level. Therefore, the application of steel bridge piers in urban highway bridge construction is increasing, and it is even gradually popularized in more complex engineering environments such as cross-sea bridges.

[0003] As a key lifeline project, bridges need to have the ability to resist natural disasters or man-made damage to ensure that they can still maintain basic functions in extreme situations and be quickly repaired after disasters, thus ensuring the smooth flow of traffic after earthquakes. However, with the increase in the service life of bridges, aging damage has become increasingly serious, which has become a major engineering and technical challenge faced by many countries. Taking the United States as an example, a large number of bridges were built from the 1920s to the 1940s. Since 1980, these bridges have gradually entered the aging stage and their structural performance has gradually deteriorated. A survey of more than 220,000 bridges in Europe shows that more than 35% of the bridges have a history of over a hundred years. In Japan, the proportion of old bridges over 50 years old was nearly 20% in 2016, and it is expected that this proportion will exceed 47% by 2026. For China, as of the end of 2023, the total number of highway bridges in the country has reached 1.0793 million, with a total length of approximately 95.2882 million linear meters. Among them, the number of old bridges in service for more than 30 years has exceeded 200,000. Moreover, a large number of in-service bridges were not designed for earthquake resistance or were built according to old earthquake-resistant design codes, making it difficult to meet the latest earthquake-resistant requirements. At the same time, long-term exposure to the atmospheric environment has also caused serious aging and damage to the main load-bearing components such as bridge piers. In view of the above situation, a large number of existing bridges in China need to be strengthened for earthquake resistance due to design defects and aging damage. As the main vertical load-bearing component of bridges, the failure of bridge piers under earthquake action may lead to the collapse of the overall bridge, seriously affecting the use function of the bridge and traffic safety. Therefore, the seismic strengthening of in-service bridges is particularly important.

[0004] It should be noted that although traditional strengthening methods can significantly improve the stiffness, ductility, and ultimate strength of in-service steel bridge piers, the additional strength and stiffness will ultimately be transferred to the pier foundation and anchorage parts, which may cause more serious problems such as irreparable foundation damage under earthquake action. Therefore, in current seismic analysis and research, another idea to improve seismic performance is to enhance the ductility of the structure rather than simply increasing the strength. Generally, the ultimate displacement of the structure is a key index to measure ductility. However, at present, no seismic strengthening structure and construction method have been proposed that can significantly improve the ductility of in-service steel bridge piers and hardly increase their strength. Therefore, it is crucial to develop a seismic strengthening method with the core goal of enhancing ductility and only slightly increasing strength. In addition, some of the currently proposed strengthening methods often involve on-site wet operations during construction, which pollute the environment and have low efficiency. For in-service steel bridge piers, there is an urgent need to propose a seismic toughness improvement structure and construction method with high construction efficiency, no on-site wet operations, and simplified construction process to significantly enhance the ductility and increase the post-earthquake displacement allowance without increasing the stiffness and strength of the bridge piers, thereby enhancing the seismic toughness of the bridge. Summary of the Invention

[0005] In view of the above-mentioned defects existing in the prior art, in order to solve the problems that the stiffness and strength of the strengthened bridge piers are too large by traditional in-service steel bridge pier strengthening methods and on-site wet operations are required, the present invention proposes a seismic toughness improvement structure, construction method, and application for in-service steel bridge piers, which can significantly improve the ductility of the bridge piers without increasing their stiffness and strength, and adopt a convenient construction method to increase the post-earthquake displacement allowance of the bridge piers, thereby enhancing the seismic toughness of the bridge.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A seismic toughness improvement structure for in-service steel bridge piers includes an in-service steel bridge pier and an existing pile cap at its lower part. The seismic toughness improvement structure for in-service steel bridge piers further includes a steel positioning ring plate, a contact longitudinal rib, and a pier bottom bearing steel plate;

[0008] The steel positioning ring plate is formed by welding two steel positioning semi-ring plates after positioning; the contact longitudinal rib is formed by welding a weakened rib plate with equal thickness and a contact end plate, and the contact end plate is horizontally arranged at the bottom end of the vertical weakened rib plate; the pier bottom bearing steel plate is formed by welding two pier bottom bearing steel splicing plates after positioning;

[0009] The existing pile cap is provided with an installation space for the pier bottom bearing steel plate; the pier bottom bearing steel plate is fixed in the reserved space in the existing pile cap; the steel positioning ring plate is welded to the outer wall of the in-service steel bridge pier; the contact longitudinal rib is welded between the in-service steel bridge pier and the steel positioning ring plate, and there is a certain gap between the contact end plate of the contact longitudinal rib and the pier bottom bearing steel plate.

[0010] Further, before welding the in-service steel pier with the steel positioning ring plate, the contact longitudinal rib and the pier bottom bearing steel plate, the welding area shall be degreased and polished first to ensure that the welding surface is clean and flat.

[0011] Further, the thickness of the contact longitudinal rib is greater than the wall thickness of the in-service steel pier. There are multiple contact longitudinal ribs, which are evenly distributed along the circumferential direction of the cross-section of the in-service steel pier.

[0012] Further, the steel materials used for the steel positioning ring plate, the contact longitudinal rib and the pier bottom bearing steel plate are the same as those of the in-service steel pier.

[0013] Further, the vertical distance between the steel positioning ring plate and the pier bottom bearing steel plate is equal to the sum of the buckling half-wavelength when the in-service steel pier fails under earthquake action and the height of the contact longitudinal rib.

[0014] Further, the outermost edge of the contact longitudinal rib needs to be inside the outermost edge of the pier bottom bearing steel plate.

[0015] Further, before the in-service steel pier fails due to buckling under earthquake action, the contact end plate in the contact longitudinal rib does not contact the pier bottom bearing steel plate.

[0016] Further, the weakened rib plate is in an inverted L shape, which includes a wide part at the upper part and a narrow part at the bottom. The top of the wide part is welded to the steel positioning ring plate, the inner side of the wide part is welded to the outer wall of the in-service steel pier, and the bottom end of the narrow part is welded to the contact end plate, thus forming an overhanging and drooping suspension structure.

[0017] The construction method of the above-mentioned seismic toughness improvement structure of the in-service steel pier includes the following steps:

[0018] S1. Evaluate the horizontal ultimate strength of the in-service steel pier when it fails under earthquake action, and design the sizes of the steel positioning ring plate, the contact longitudinal rib and the pier bottom bearing steel plate;

[0019] S2. Treat the concrete of the existing bearing platform and reserve a space for installing the pier bottom bearing steel plate;

[0020] S3. Position and place the pier bottom bearing steel splicing plates on both sides of the in-service steel pier, make them completely fit the existing bearing platform and the in-service steel pier, and weld and fix the two pier bottom bearing steel splicing plates and the in-service steel pier respectively;

[0021] S4. Design the vertical distance between the steel positioning ring plate and the pier bottom bearing steel plate according to the size of the contact longitudinal rib;

[0022] S5. Position and install the steel positioning semi-ring plates on both sides of the in-service steel pier, make them completely fit the in-service steel pier, and weld and fix the two steel positioning semi-ring plates and the in-service steel pier respectively;

[0023] S6. Fit the top ends of the contact longitudinal ribs against the steel positioning ring plate and distribute them at equal intervals along the circumferential direction of the cross-section of the in-service steel bridge pier. At the same time, weld and fix them to the in-service steel bridge pier and the steel positioning ring plate respectively.

[0024] An application of a seismic toughness improvement structure for in-service steel bridge piers, which adopts the above-mentioned seismic toughness improvement structure for in-service steel bridge piers. The seismic toughness improvement structure for in-service steel bridge piers is applied to steel bridge piers with socket-and-spigot circular cross-sections or rectangular cross-sections, and the steel bridge piers are single-column piers, double-column piers or other combined piers.

[0025] After adopting the above technical solution, the present invention has at least one of the following beneficial effects compared with the prior art:

[0026] By simply transforming the bottom of the in-service steel bridge pier and adopting a fully welded construction form, the present invention completely gets rid of the adverse effects brought by on-site wet operations, and cleverly utilizes the contact effect. Without increasing the stiffness and strength of the bridge pier, the ductility is significantly improved, the post-earthquake displacement allowance is increased, and thus the seismic toughness of the bridge is enhanced.

[0027] When the in-service steel bridge pier reaches the limit state under earthquake action, the additional contact longitudinal ribs come into contact with the pier bottom bearing steel plate, and the continuous increase of earthquake load is resisted through the deformation of the contact longitudinal ribs themselves. This deformation of the contact longitudinal ribs themselves is continuously supplemented along with the earthquake action. Therefore, the transformed steel bridge pier has more excellent energy dissipation capacity and ductility, and will not increase the strength and continuity of the steel bridge pier, thus will not bring additional load burden to the foundation or anchorage part, and significantly improves the seismic toughness of the in-service steel bridge pier.

[0028] The proposed seismic toughness improvement structure for in-service steel bridge piers adopts a fully welded construction method, which is convenient for construction, has a short construction period, avoids on-site wet operations, and can greatly reduce the interference to the existing traffic caused by construction; the present invention has a wide range of applicable scenarios and is applicable to different pier cross-section forms, single-column piers, double-column piers, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is the overall schematic diagram of the seismic toughness improvement structure for in-service steel bridge piers of the present invention;

[0030] Figure 2 is the disassembled view of the seismic toughness improvement structure for in-service steel bridge piers of the present invention;

[0031] Figure 3 is the detailed view of the contact longitudinal ribs in the seismic toughness improvement structure for in-service steel bridge piers of the present invention;

[0032] Figure 4 is the effective mechanism diagram of the seismic toughness improvement structure for in-service steel bridge piers of the present invention during an earthquake;;

[0033] Figure 5 It is the overall schematic diagram of the structure for enhancing the seismic toughness of in-service steel bridge piers in the present invention when strengthening rectangular-section bridge piers;

[0034] Figure 6 It is the construction flow chart of the structure for enhancing the seismic toughness of in-service steel bridge piers in the present invention.

[0035] Reference numerals:

[0036] 1—in-service steel bridge pier; 2—steel positioning ring plate; 3—contact longitudinal rib; 4—pier bottom bearing steel plate; 5—existing bearing platform; 6—steel positioning semi-ring plate; 7—pier bottom bearing steel splicing plate; 8—weakening rib plate; 9—contact end plate. Specific implementation mode

[0037] Next, in combination with the attached Figure 1-6 drawings and specific implementations, the present invention will be further described in detail to facilitate a clear understanding of the present invention, but they do not constitute a limitation to the present invention.

[0038] Example 1

[0039] As shown in the attached Figure 1-5 drawings, a structure for enhancing the seismic toughness of an in-service steel bridge pier in this embodiment includes an in-service steel bridge pier 1 and an existing bearing platform 5 below it. The structure for enhancing the seismic toughness of the in-service steel bridge pier further includes a steel positioning ring plate 2, a contact longitudinal rib 3, and a pier bottom bearing steel plate 4.

[0040] As Figure 2 shown in the drawings, the steel positioning ring plate 2 is formed by welding two steel positioning semi-ring plates 6 after positioning. The contact longitudinal rib 3 is formed by welding multiple weakening rib plates 8 of equal thickness and a contact end plate 9. The contact end plate 9 is horizontally arranged at the bottom end of the vertical weakening rib plate 8. The pier bottom bearing steel plate 4 is formed by welding two pier bottom bearing steel splicing plates 7 after positioning.

[0041] In this embodiment, the existing bearing platform 5 reserves an installation space for the pier bottom bearing steel plate 4. The pier bottom bearing steel plate 4 is fixed in the reserved space in the existing bearing platform 5. The steel positioning ring plate 2 is welded to the outer wall of the in-service steel bridge pier 1. The contact longitudinal rib 3 is welded between the in-service steel bridge pier 1 and the steel positioning ring plate 2, and there is a certain gap between the contact end plate 9 of the contact longitudinal rib 3 and the pier bottom bearing steel plate 4.

[0042] In this embodiment, before welding the in-service steel bridge pier 1 with the steel positioning ring plate 2, the contact longitudinal rib 3, and the pier bottom bearing steel plate 4, the welding area needs to be degreased and polished first to ensure that the welding surface is clean and flat.

[0043] In addition, in this embodiment, as Figure 2As shown, the thickness of the contact longitudinal rib 3 is greater than the wall thickness of the in-service steel pier 1. There are multiple contact longitudinal ribs 3, which are evenly distributed along the circumferential direction of the cross-section of the in-service steel pier 1. Moreover, the steel materials used for the steel positioning ring plate 2, the contact longitudinal rib 3, and the pier bottom bearing steel plate 4 are the same as those of the in-service steel pier 1.

[0044] As Figure 3 shown, the weakened rib plate 8 is in an inverted L shape, which includes a wide part at the upper part and a narrow part at the bottom. The top of the wide part is welded to the steel positioning ring plate 2, the inner side of the wide part is welded to the outer wall of the in-service steel pier 1, and the bottom end of the narrow part is welded to the contact end plate 9, thus forming a hanging structure that extends outward and droops. In this embodiment, the vertical distance between the steel positioning ring plate 2 and the pier bottom bearing steel plate 4 is equal to the sum of the buckling half-wavelength when the in-service steel pier 1 fails under earthquake action and the height of the contact longitudinal rib 3. The outermost edge of the contact longitudinal rib 3 needs to be within the outermost edge of the pier bottom bearing steel plate 4. Before the in-service steel pier 1 undergoes buckling failure under earthquake action, the contact end plate 9 in the contact longitudinal rib 3 does not come into contact with the pier bottom bearing steel plate 4.

[0045] The principle of this embodiment is: As Figure 1 、 3 and 4 shown, the contact longitudinal rib 3 welded by the weakened rib plate 8 and the contact end plate 9 with equal thickness is welded to the bottom of the in-service steel pier 1, and the contact end plate 9 and the pier bottom bearing steel plate 4 maintain a certain vertical distance. Under earthquake action, when the in-service steel pier 1 reaches the horizontal ultimate strength and undergoes local buckling, the contact end plate 9 of the contact longitudinal rib 3 comes into contact with the pier bottom bearing steel plate 4, and the continuous increasing earthquake load is resisted through the deformation of the contact longitudinal rib 3 itself.

[0046] In addition, as Figure 1 shown, this seismic toughness improvement structure for in-service steel piers is applicable to socketed circular-section steel piers, and the steel pier is a single-column pier.

[0047] Embodiment 2

[0048] As Figure 5 shown, in this embodiment, this seismic toughness improvement structure for in-service steel piers is applicable to socketed rectangular-section steel piers, and the steel pier is a double-column pier. The seismic toughness improvement structure for in-service steel piers is the same as that in Embodiment 1 and will not be elaborated here.

[0049] Embodiment 3

[0050] As Figure 6 shown, the construction method of the seismic toughness improvement structure for in-service steel piers in the above Embodiments 1-2 includes the following steps:

[0051] S1. Evaluate the horizontal ultimate strength of the in-service steel pier 1 when it fails under earthquake action, and design the sizes of the steel positioning ring plate 2, the contact longitudinal rib 3, and the pier bottom bearing steel plate 4.

[0052] S2. Process the concrete of the existing bearing platform 5 and reserve a space for installing the bearing steel plate 4 at the bottom of the pier.

[0053] S3. Locate and place the bearing steel splicing plates 7 at the bottom of the pier on both sides of the in-service steel pier 1 so that they fully fit the existing bearing platform 5 and the in-service steel pier 1, and weld and fix the two bearing steel splicing plates 7 and the in-service steel pier 1 respectively.

[0054] S4. Design the vertical distance between the steel positioning ring plate 2 and the bearing steel plate 4 at the bottom of the pier according to the size of the contact longitudinal rib 3.

[0055] S5. Locate and install the steel positioning semi-ring plates 6 on both sides of the in-service steel pier 1 so that they fully fit the in-service steel pier 1, and weld and fix the two steel positioning semi-ring plates 6 and the in-service steel pier 1 respectively.

[0056] S6. Fit the top end of the contact longitudinal rib 3 to the steel positioning ring plate 2 and distribute them at equal intervals along the circumferential direction of the cross-section of the in-service steel pier 1. At the same time, weld and fix them to the in-service steel pier 1 and the steel positioning ring plate 2 respectively.

[0057] The above is only the preferred embodiment of the present invention, and it does not impose any form of limitation on the structure of the present invention. The layout type and the number of uses of the present invention are not limited to this example, and can be optimized according to the actual situation of the project. Any modification, equivalent change and decoration made to the above embodiments based on the technical principle of the present invention without departing from the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A structure for improving the seismic toughness of an in-service steel bridge pier, comprising an in-service steel bridge pier (1) and an existing bearing platform (5) at the bottom thereof, characterized in that: The in-service steel bridge pier seismic toughness improvement structure also includes a steel positioning ring plate (2), a contact longitudinal rib (3) and a pier bottom bearing steel plate (4); The steel positioning ring plate (2) is formed by welding two steel positioning half ring plates (6) after positioning; the contact longitudinal rib (3) is formed by welding a weakened rib plate (8) and a contact end plate (9) of equal thickness, and the contact end plate (9) is horizontally arranged at the bottom end of the vertical weakened rib plate (8); the pier bottom bearing steel plate (4) is formed by welding two pier bottom bearing steel splicing plates (7) after positioning; The existing cap (5) has reserved installation space for the pier bottom bearing steel plate (4); the pier bottom bearing steel plate (4) is fixed in the reserved space in the existing cap (5); the steel positioning ring plate (2) is welded to the outer wall of the in-service steel bridge pier (1); the contact longitudinal rib (3) is welded between the in-service steel bridge pier (1) and the steel positioning ring plate (2), and a certain gap is reserved between the contact end plate (9) of the contact longitudinal rib (3) and the pier bottom bearing steel plate (4).

2. The structure for improving the seismic toughness of an in-service steel bridge pier according to claim 1, characterized in that: Before the in-service steel bridge pier (1) is welded with the steel positioning ring plate (2), the contact longitudinal rib (3) and the pier bottom bearing steel plate (4), the welding area must be depainted and polished to ensure that the welding surface is clean and flat.

3. The structure for improving the seismic toughness of an in-service steel bridge pier according to claim 1, characterized in that: The thickness of the contact longitudinal rib (3) is greater than the wall thickness of the in-service steel bridge pier (1); the contact longitudinal rib (3) is multiple and is evenly spaced along the circumferential direction of the cross section of the in-service steel bridge pier (1).

4. The structure for improving the seismic toughness of an in-service steel bridge pier according to claim 1, characterized in that: The steel positioning ring plate (2), the contact longitudinal ribs (3) and the pier bottom bearing steel plate (4) are made of the same steel material as that of the in-service steel bridge pier (1).

5. The structure for improving the seismic toughness of an in-service steel bridge pier according to claim 1, characterized in that: The vertical distance between the steel positioning ring plate (2) and the pier bottom bearing steel plate (4) is equal to the sum of the buckling half wavelength of the in-service steel bridge pier (1) when it is damaged under earthquake action and the height of the contact longitudinal rib (3).

6. The structure for improving the seismic toughness of an in-service steel bridge pier according to claim 1, characterized in that: The outermost edge of the contact longitudinal rib (3) needs to be inside the outermost edge of the pier bottom bearing steel plate (4).

7. The structure for improving the seismic toughness of an in-service steel bridge pier according to claim 1, characterized in that: Before the in-service steel bridge pier (1) buckles and fails under earthquake action, the contact end plate (9) in the contact longitudinal rib (3) does not come into contact with the pier bottom bearing steel plate (4).

8. The structure for improving the seismic toughness of an in-service steel bridge pier according to claim 1, characterized in that: The weakened rib plate (8) is in an inverted L-shape, comprising a wide portion at the top and a narrow portion at the bottom, the top of the wide portion is welded to the steel positioning ring plate (2), the inner side of the wide portion is welded to the outer wall of the in-service steel bridge pier (1), and the bottom end of the narrow portion is welded to the contact end plate (9), thereby forming an outwardly extending and drooping suspension structure.

9. A construction method for improving the seismic toughness of an in-service steel bridge pier according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Evaluate the horizontal ultimate strength of the in-service steel bridge pier (1) under earthquake damage, and design the dimensions of the steel locating ring plate (2), the contact longitudinal rib (3) and the pier bottom bearing steel plate (4); S2. Processing the existing concrete cap (5), leaving space for installing the pier bottom bearing steel plate (4); S3. Position and place the pier bottom bearing steel splicing plates (7) from both sides of the in-service steel pier (1) so that they completely fit the existing cap (5) and the in-service steel pier (1), and respectively weld and fix the two pier bottom bearing steel splicing plates (7) and the in-service steel pier (1); S4. Design the vertical distance between the steel positioning ring plate (2) and the pier bottom bearing steel plate (4) according to the size of the contact longitudinal rib (3); S5. Positioning and installing the steel positioning semi-ring plates (6) from both sides of the in-service steel pier (1) so that they completely fit the in-service steel pier (1), and respectively welding and fixing the two steel positioning semi-ring plates (6) and the in-service steel pier (1); S6. The top end of the contact longitudinal rib (3) is fitted to the steel positioning ring plate (2) and is evenly spaced along the circumferential direction of the cross section of the in-service steel bridge pier (1). At the same time, it is welded and fixed to the in-service steel bridge pier (1) and the steel positioning ring plate (2) respectively.

10. An application of a structure for improving the seismic toughness of an in-service steel bridge pier, which adopts the structure for improving the seismic toughness of an in-service steel bridge pier as claimed in any one of claims 1 to 8, characterized in that: The structure for improving the seismic toughness of in-service steel bridge piers is applied to socket-type steel bridge piers with circular or rectangular cross-sections, and the steel bridge piers are single-column piers, double-column piers or other combined piers.

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