Opening structure of longitudinal rib passing part on cross diaphragm in orthotropic steel bridge deck

Abstract

The utility model relates to a kind of longitudinal rib through part hole structure in cross-deck of orthotropic steel bridge deck. Its hole type is made of bottom straight line section, upper straight line section of both sides and the straight line transition section of connecting middle arc section and bottom arc section, and the radian of middle arc section is 55 °;Straight line transition section is tangent with middle arc section and bottom arc section, and parallel with upper straight line section.The utility model has the beneficial effect that the stress amplitude of longitudinal rib and cross-deck cross-welding details and cross-deck arc-shaped opening position can be significantly reduced, the stress distribution state is improved, fatigue crack initiation is delayed, the fatigue resistance of the structure details is effectively improved, thereby prolonging its fatigue life;A new idea is provided for the design of longitudinal rib through part hole structure on cross-deck of orthotropic steel bridge deck.

Description

Technical Field

[0001] This utility model relates to an orthotropic steel bridge deck structure, and particularly to an orthotropic steel bridge deck structure with openings at the longitudinal ribs passing through the transverse diaphragm. Background Technology

[0002] Orthotropic steel bridge decks are a type of bridge deck structure with significant advantages in steel bridges. However, due to their low stiffness, complex construction, and direct bearing of cyclic wheel loads, the fatigue stress at the arc-shaped openings of the diaphragms is complex. Under long-term external random traffic loads, fatigue problems in this area are particularly prominent. Existing engineering practice and related research show that under ultra-high cycle cyclic loading, approximately 78% of steel bridge deck defects originate from two typical types of fatigue cracks: penetrating cracks (52%) initiating at the weld toe of the intersection weld between the longitudinal ribs and the diaphragms, and base material cracks at the arc-shaped openings of the diaphragms (26%). The fundamental cause lies in the fact that the stress distribution at the intersection weld between the longitudinal ribs and the diaphragms and at the arc-shaped openings of the diaphragms is mainly affected by the opening type and its geometric parameter matching, thus exhibiting a high stress concentration effect.

[0003] The four typical opening structures (elliptical holes, round-ended rectangular holes, hyperbolic holes, and combined curved holes) recommended in the current design specifications for the longitudinal ribs passing through the transverse diaphragms of orthotropic steel bridge decks can alleviate the problem of local stress concentration to a certain extent, but the following problems still exist: (1) The stress concentration factor (SCF) is still as high as 2.8~3.5, exceeding the allowable value of fatigue strength (1.8~2.2); (2) The direction of the maximum principal stress at the edge of the hole forms an angle of 15°~25° with the direction of the weld, forming a local composite stress field that is relatively unfavorable to the stress; (3) The quantitative correlation between the opening shape parameters (such as the radius of the transition arc, the inclination angle of the straight section, etc.) and the fatigue life is missing, which leads to the parameter selection mainly relying on engineering experience. Therefore, reasonable design and optimization of the opening type of the transverse diaphragms of orthotropic steel bridge decks to significantly reduce the local fatigue stress amplitude and improve its fatigue resistance, thereby alleviating or avoiding fatigue cracking in fatigue stress sensitive parts, is a key issue to be addressed in the fatigue-resistant design of orthotropic steel bridge decks. Utility Model Content

[0004] In view of the above understanding, this utility model proposes a new type of perforation structure for the longitudinal ribs passing through the transverse diaphragm in orthotropic steel bridge decks, based on the design concept and development trend of fatigue resistance of orthotropic steel bridge decks. This new structure addresses the problem that the local stress amplitude caused by the opening structure at the longitudinal rib passage part of the existing transverse diaphragm is too high, which easily leads to premature fatigue cracking in the details of the cross welding between the longitudinal ribs and the transverse diaphragm and the arc-shaped opening part of the transverse diaphragm.

[0005] The purpose of this invention is to provide an opening structure at the longitudinal rib passage of the transverse diaphragm in an orthotropic steel bridge deck, so as to minimize the stress amplitude at the cross welding details of the longitudinal rib and the transverse diaphragm and the arc-shaped opening of the transverse diaphragm, significantly reduce the local fatigue stress amplitude, delay or even avoid the initiation of fatigue cracks, and thus significantly improve its fatigue resistance.

[0006] The technical solution adopted by this utility model to solve its technical problem is: A perforation structure for the longitudinal ribs passing through the transverse diaphragm in an orthotropic steel bridge deck, the perforation structure of the transverse diaphragm includes a bottom straight section and upper straight sections on both sides, a middle arc section and a straight transition section, and a bottom arc section; the upper straight section forms a 79° angle with the top plate of the steel bridge deck, and the arc of the middle arc section is 55°.

[0007] Preferably, the straight transition segment is tangent to both the middle and bottom arc segments and parallel to the upper straight segment; the bottom arc segment is tangent to the bottom straight segment.

[0008] Preferably, the perforation on the diaphragm is a symmetrical structure.

[0009] Preferably, the upper straight section has a length of 240~270mm and is parallel to the web of the U-shaped longitudinal rib.

[0010] Preferably, the bottom of the U-shaped longitudinal rib is parallel to the bottom straight segment.

[0011] Preferably, the radius of the central arc segment is 35~55mm.

[0012] Preferably, the length of the straight transition section is 25~45mm.

[0013] Preferably, the radius of the bottom arc segment is 70~90mm.

[0014] Preferably, the length of the bottom straight segment is 50~70mm.

[0015] Preferably, the distance from the bottom straight section to the bottom of the U-shaped longitudinal rib is 90~110mm.

[0016] Compared with the existing structure of openings at the longitudinal rib passages on transverse diaphragms, the advantages of this utility model are: This invention relates to an opening structure at the longitudinal rib passage location on the transverse diaphragm of an orthotropic steel bridge deck. This structure can significantly reduce the stress amplitude at the intersection welding details of the longitudinal ribs and the transverse diaphragm, as well as at the arc-shaped opening location on the transverse diaphragm, thereby improving the stress distribution, delaying the initiation of fatigue cracks, effectively enhancing the fatigue resistance of this structural detail, and thus extending its fatigue life. It provides a new approach to the design of opening structures at the longitudinal rib passage location on the transverse diaphragm of orthotropic steel bridge decks. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0018] Figure 1 This is a schematic diagram of the opening structure at the longitudinal rib passage of the transverse diaphragm of the orthotropic steel bridge deck of this utility model; Figure 2 for Figure 1 Enlarged view of section B, detailing the construction of the opening where the longitudinal ribs pass through the central transverse diaphragm; Figure 3 A schematic diagram of the opening structure at the longitudinal rib passage of the transverse diaphragm of a highway bridge deck, as recommended by the Eurocode 3 specification; Figure 4 for Figure 3 Enlarged view of the partial structural details of the opening where the longitudinal ribs pass through the central transverse diaphragm, area A; Figure 5 This is a three-dimensional schematic diagram showing the details of the cross welding of the longitudinal ribs and transverse diaphragms in an embodiment of this utility model; Figure 6 For Eurocode 3 specifications, the opening structure at the longitudinal rib crossing part of the transverse diaphragm is recommended. The details of the cross welding of the longitudinal rib and transverse diaphragm under the most unfavorable wheel load conditions are shown in the principal stress cloud diagram at the weld toe end. Figure 7 Principal stress cloud diagram of the arc-shaped opening in the diaphragm under the most unfavorable wheel load conditions, for the opening structure of the longitudinal rib passing through the diaphragm recommended by the Eurocode3 specification. Figure 8 This is a principal stress cloud diagram of the weld toe end of the longitudinal rib and transverse diaphragm cross welding details under the most unfavorable wheel load conditions in an embodiment of this utility model. Figure 9 This is a principal stress cloud diagram of the arc-shaped opening of the transverse diaphragm under the most unfavorable wheel load conditions in an embodiment of this utility model; Figure 10 This is a schematic diagram showing the comparison of the maximum principal stress at the weld toe end of the longitudinal rib crossing section of the transverse diaphragm, in accordance with the embodiment of this utility model and the Eurocode 3 specification recommended for the hole structure at the longitudinal rib crossing section of the transverse diaphragm under different wheel load conditions in the transverse direction.

[0019] Figure 11 This diagram illustrates a comparison of the maximum principal stress at the arc-shaped opening of the diaphragm under different wheel load conditions in the transverse direction, representing an embodiment of this utility model and the opening structure at the longitudinal rib passage location on the transverse diaphragm recommended by the Eurocode 3 standard.

[0020] Figure 12 This is a schematic diagram showing the comparison of the maximum principal stress at the weld toe end of the cross-welding details of the longitudinal ribs and transverse diaphragms under different wheel load conditions in the longitudinal direction of the present utility model embodiment and the Eurocode 3 specification recommended opening structure at the longitudinal ribs passing through the transverse diaphragm.

[0021] The parts shown in the diagram and their corresponding markings are: U-shaped longitudinal rib 6, transverse diaphragm 7, upper straight segment L1, middle arc segment L2, straight transition segment L3, bottom arc segment L4, and bottom straight segment L5. Detailed Implementation

[0022] To better understand the above-mentioned objectives, features, and advantages of this utility model, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. Many specific details are set forth in the following description to provide a full understanding of the present utility model; however, the present utility model may also be implemented in other ways different from those described herein, and therefore, the present utility model is not limited to the specific embodiments disclosed below.

[0023] Figure 3 This is a perforation structure for the longitudinal ribs passing through the transverse diaphragms of highway bridge steel decks, recommended by Eurocode 3 specifications. Its features include a bottom straight section L5, upper straight sections L1 on both sides, a middle arc section L2, a straight transition section L3, and a bottom arc section L4. (Refer to...) Figure 4 The central arc segment L2 has an arc angle of 74°. This structure is prone to local out-of-plane deformation of the diaphragm under long-term external random traffic loads, thus forming a local composite stress field with relatively unfavorable stress. Example

[0024] Reference Figure 1 , Figure 2 and Figure 5 The present invention relates to an orthotropic steel bridge deck diaphragm with an opening structure at the longitudinal rib passage portion. The opening structure of the diaphragm 7 includes a bottom straight section L5, upper straight sections L1 on both sides, a middle arc section L2, a straight transition section L3, and a bottom arc section L4. Compared to... Figure 3Regarding the opening structure at the longitudinal rib passage of the central diaphragm, the upper straight section L1 has a length of 240~270mm and is parallel to the web of the U-shaped longitudinal rib 6, forming a 79° angle with respect to the top plate of the steel bridge deck; the middle arc section L2 has a radius of 35~55mm and an arc of 55° to reduce local out-of-plane deformation of the diaphragm and improve the local composite stress field where the stress is relatively unfavorable; the straight transition section L3 has a length of 25~45mm, is tangent to both the middle arc section L2 and the bottom arc section L4, and is also tangent to the upper straight section L1. The parallel line segment L1, through dual curvature control, achieves a smooth transition of the stress diffusion path, effectively eliminating the stress concentration phenomenon caused by the abrupt connection between straight lines and arcs in traditional structures; the bottom straight line segment L5 is parallel to the bottom of the U-shaped longitudinal rib 6, with a length of 50~70mm and a distance of 90~110mm from the bottom of the U-shaped longitudinal rib 6; the bottom arc segment L4 has a radius of 70~90mm and is tangent to the bottom straight line segment L5, which can effectively reduce the stress gradient at the edge of the arc-shaped opening of the transverse diaphragm.

[0025] To further illustrate the gain effect of this embodiment, the inventors compared the maximum principal stress at the fatigue-prone locations of the longitudinal ribs and transverse diaphragms in the opening structure of the longitudinal ribs passing through the transverse diaphragms of the present invention with that in the Eurocode 3 recommended highway bridge steel bridge deck transverse diaphragm. This comparison included details of the weld toe ends at the longitudinal ribs and the arc-shaped openings in the transverse diaphragms. Figure 6 , Figure 7 , Figure 8 and Figure 9 As shown. Finite element analysis verified that, under transverse bridge wheel load conditions, the stress amplitude at the weld toe of the longitudinal rib and transverse diaphragm intersection welding detail of this invention is reduced by approximately 23% compared to the Eurocode 3 recommended opening structure at the longitudinal rib passage location on the transverse diaphragm; the stress amplitude at the arc-shaped opening of the transverse diaphragm is reduced by approximately 3%; and under longitudinal bridge wheel load conditions, the stress amplitude at the weld toe of the longitudinal rib and transverse diaphragm intersection welding detail is reduced by approximately 24%. Figure 10 , Figure 11 and Figure 12 As shown. Therefore, compared with the opening structure at the longitudinal rib crossing part of the transverse diaphragm of highway bridge steel bridge deck recommended by Eurocode 3, the present invention can minimize the stress amplitude at the cross welding details of the longitudinal rib and the transverse diaphragm and the arc-shaped opening part of the transverse diaphragm, and effectively extend the stress diffusion path, significantly improve the stress distribution state at the edge of the arc-shaped opening of the transverse diaphragm, delay the initiation of fatigue cracks, and thus obtain better fatigue resistance.

[0026] The above description is merely an illustration of some principles of the opening structure at the longitudinal rib passage of the transverse diaphragm of the orthotropic steel bridge deck of this utility model. It is not intended to limit this utility model to the specific structure and applicable scope shown and described. Therefore, all possible modifications and equivalents that may be used fall within the patent scope of this utility model.

Claims

1. A perforation structure at the longitudinal rib passage portion of a transverse diaphragm in an orthotropic steel bridge deck, characterized in that, The diaphragm opening structure includes a bottom straight section and upper straight sections on both sides, a middle arc section and a straight transition section, and a bottom arc section; the upper straight section forms a 79° angle with the top plate of the steel bridge deck, and the arc of the middle arc section is 55°.

2. The perforation structure at the longitudinal rib passage portion of the transverse diaphragm in an orthotropic steel bridge deck according to claim 1, characterized in that, The straight transition segment is tangent to both the middle and bottom arc segments and parallel to the upper straight segment; the bottom arc segment is tangent to the bottom straight segment.

3. The perforation structure at the longitudinal rib passage portion of the transverse diaphragm in an orthotropic steel bridge deck according to claim 1, characterized in that, The perforated structure on the diaphragm is symmetrical.

4. The perforation structure at the longitudinal rib passage portion of the transverse diaphragm in an orthotropic steel bridge deck according to claim 1, characterized in that, The upper straight section is 240-270 mm long and parallel to the web of the U-shaped longitudinal rib.

5. The perforation structure at the longitudinal rib passage portion of the transverse diaphragm in an orthotropic steel bridge deck according to claim 4, characterized in that, The bottom of the U-shaped longitudinal rib is parallel to the bottom straight segment.

6. The perforation structure at the longitudinal rib passage portion of the transverse diaphragm in an orthotropic steel bridge deck according to claim 1, characterized in that, The radius of the central arc segment is 35~55mm.

7. The perforation structure at the longitudinal rib passage portion of the transverse diaphragm in an orthotropic steel bridge deck according to claim 1, characterized in that, The length of the straight transition section is 25~45mm.

8. The perforation structure at the longitudinal rib passage portion of the transverse diaphragm in an orthotropic steel bridge deck according to claim 1, characterized in that, The radius of the bottom arc segment is 70~90mm.

9. The perforation structure at the longitudinal rib passage portion of the transverse diaphragm in an orthotropic steel bridge deck according to claim 1, characterized in that, The length of the bottom straight segment is 50~70mm.

10. The perforation structure at the longitudinal rib passage portion of the transverse diaphragm in an orthotropic steel bridge deck according to claim 5, characterized in that, The distance from the bottom straight section to the bottom of the U-shaped longitudinal rib is 90~110mm.

Images