Novel swinging self-resetting bridge pier with prestressed tendons arranged in curve mode

Abstract

The invention discloses a novel swinging self-resetting bridge pier with curved prestressed tendons, and belongs to the technical field of impact resistance toughness improvement of swinging bridge piers. Two prestressed tendons which are arranged in a preset parabola shape are pre-buried in the bridge pier and are symmetrically arranged relative to the central axis of the section of the bridge pier; the prestressed steel bars penetrate through the pier body through a post-tensioning process to form a transverse and longitudinal bidirectional pre-compression field, and the prestressed steel bars are subjected to unbonded treatment at the joint interface in the pier body. The curved prestressed tendons are adopted to replace traditional linear prestressed tendons, the equivalent restoring force which is evenly distributed can be provided under the action of impact loads, spatial dislocation and complex deformation of a swing interface are effectively adapted, and the anti-collision performance and function restorability of the swing bridge in the service period are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of improving the anti-collision toughness of a rocking bridge pier, and specifically relates to a novel rocking self-resetting bridge pier with prestressed tendons arranged in a curve. Background Art

[0002] With the promotion of the seismic toughness design concept, the swing bridge, as a new type of seismic resistant structure, can not only achieve the design goal of "not collapsing in a major earthquake", but also quickly restore traffic functions after an earthquake, significantly improving the seismic performance and repairability of the bridge, and becoming an important advancement in my country's bridge seismic technology. By allowing controlled rotation between the pier and the foundation, the swing bridge effectively dissipates seismic energy and reduces structural damage, thereby achieving rapid recovery of post-earthquake functions. However, in addition to bearing seismic loads, the swing bridge may also face extreme effects such as vehicle collisions and rockfall impacts during actual use. These impact loads have the characteristics of large amplitude, short action time, and significant local effects, which will cause spatial dislocation of the swing interface or even overall instability, thereby losing the controllability of bridge damage and the recoverability of function, and failing to achieve the goals of anti-collapse and rapid functional recovery under impact.

[0003] At present, the design of swaying bridges is mainly aimed at earthquake loads, and their prestressed tendons are usually arranged in a straight line. This arrangement can effectively provide restoring force under earthquake loads, but it is obviously insufficient under impact loads. The impact effect is mainly manifested as shear load, so the straight line arrangement is difficult to adapt to the complex deformation caused by the impact, and cannot provide sufficient equivalent restoring force to achieve post-impact reset, resulting in reduced controllability of the swaying interface, affecting the overall safety and functional recovery ability of the bridge.

[0004] In view of this, the present invention proposes an innovative curved prestressed tendon arrangement method. By using curved prestressed tendons instead of traditional straight prestressed tendons, it is possible to provide uniformly distributed equivalent restoring force under impact loads, effectively adapt to the spatial dislocation and complex deformation of the rocking interface, and improve the anti-collision performance and functional recoverability of the rocking bridge during its service life. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a new type of rocking self-resetting pier with curved prestressed tendons, which is particularly suitable for rocking bridges and can provide greater elastic restoring force in the event of impact damage to the pier. It has excellent shear resistance and does not affect the bending resistance of the pier. Compared with the widely used straight-line vertical prestressed system, it has better crack resistance and bending resistance, and greatly improves the pier body reset function.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a novel swinging self-resetting pier with prestressed tendons arranged in a curve, wherein two prestressed steel bars arranged in a preset parabola shape are pre-embedded in the pier, and the two prestressed steel bars are symmetrically arranged about the central axis of the pier cross section, and the prestressed steel bars are arranged through the pier body by a post-tensioning process to form a transverse and longitudinal bidirectional prestressing force field, and the prestressed steel bars are treated without bonding at the joint interface in the pier body.

[0008] Furthermore, the equation of the preset parabola is:

[0009]

[0010] Among them, e(x) is the eccentricity; e is the maximum eccentricity; h is half of the height of the swing pier; and x is the position of the prestressed steel bar in the pier height direction.

[0011] Furthermore, the bridge pier includes a foundation cap, a pier body and a pier top cap beam which are fixedly connected in sequence from bottom to top, the prestressed steel bars are arranged through the pier body by a post-tensioning process, the two ends of the prestressed steel bars are respectively anchored to the anchor plates in the pier top cap beam and the foundation cap, and prestressing is applied to the prestressed steel bars by a super-tensioning process.

[0012] Furthermore, the construction method of the self-resetting bridge pier comprises the following steps:

[0013] S1: During the concrete pouring stage of the foundation cap and the pier body, a high-strength corrugated sleeve with a preset parabolic shape is pre-embedded along the axis of the pier. The corrugated sleeves are arranged continuously. The inner diameter of the corrugated sleeve is 20-30mm larger than the diameter of the prestressed steel bar. The spacing between adjacent corrugated sleeves is not less than 5 times the diameter of the prestressed steel bar.

[0014] S2: An anchor plate is fixedly installed in the foundation cap, and an adjustable anchor plate is installed in the pier cap beam, wherein the anchor plate is provided with a trumpet-shaped guide hole corresponding to the prestressed steel bar, and the inner wall of the guide hole is provided with a wear-resistant nylon bushing;

[0015] S3: After the prestressed steel bars are installed in the corrugated sleeve, the intelligent tensioning system is used to implement graded tensioning: first, 10% σ con Pre-tightening force, eliminating the gap between steel strands Formal tensioning: Loading in three levels to 105%σ con Each level holds the load for 5 minutes and then drops to 100%σ con Lock; where σ con To design tension control stress.

[0016] The beneficial effects of the present invention are:

[0017] The present invention adopts curved prestressed tendons instead of traditional straight prestressed tendons, which can provide uniformly distributed equivalent restoring force under impact loads, effectively adapt to the spatial dislocation and complex deformation of the rocking interface, and improve the anti-collision performance and functional recoverability of the rocking bridge during its service life; the arrangement of curved prestressed tendons can generate effective prestress within the span of the rocking pier column without affecting the seismic performance, has good shear impact resistance, low peak slip, and the ability of the pier to reset after impact is improved by about 25.6% compared with straight reinforcement.

[0018] Other advantages, objectives and features of the present invention will be described in the following description and will be apparent to those skilled in the art to some extent, or those skilled in the art may be taught from the practice of the present invention. The objectives and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration:

[0020] Figure 1 It is a schematic diagram of the prestressed tendon arrangement structure according to an embodiment of the present invention;

[0021] Figure 2 A schematic diagram of a prestressed tendon arrangement model according to an embodiment of the present invention;

[0022] Figure 3 It is a schematic diagram of the straight prestressed tendon swinging to the left;

[0023] Figure 4 It is a schematic diagram of the linear prestressed tendons swinging to the right;

[0024] Figure 5 A schematic diagram of a curved prestressed tendon swinging to the left according to an embodiment of the present invention;

[0025] Figure 6 This is a schematic diagram of a curved prestressed tendon swinging to the right according to an embodiment of the present invention;

[0026] Figure 7 The following is a graph showing the variation of the bottom displacement of a sway bridge pier under impact load with time for the arrangement of straight and curved prestressed tendons according to an embodiment of the present invention;

[0027] Figure 8 It is a prestress time history curve diagram of the pier bottom of the rocking bridge pier under impact load with the arrangement of straight and curved prestressed tendons in the embodiment of the present invention;

[0028] Fig. 9 A graph showing the displacement of the top of a swaying pier under impact load versus time for arrangements of straight and curved prestressed tendons according to an embodiment of the present invention;

[0029] Fig.10 It is a prestress time history curve diagram of the pier top of the rocking bridge pier under impact load according to the arrangement of straight and curved prestressed tendons in the embodiment of the present invention.

[0030] The markings in the attached drawings are as follows: foundation cap 1, pier body 2, pier top cap beam 3, prestressed steel bars 4. DETAILED DESCRIPTION

[0031] like Figures 1 to 10 As shown, the present invention provides a new type of rocking self-resetting pier with prestressed tendons arranged in a curved shape, wherein two prestressed steel bars 4 arranged in a preset parabolic shape are pre-embedded in the pier, and the two prestressed steel bars 4 are symmetrically arranged about the central axis of the pier cross section, wherein the pier comprises a foundation pedestal 1, a pier body 2 and a pier top cap beam 3 which are fixedly connected in sequence from top to top, the prestressed steel bars 4 are arranged through the pier body 2 by a post-tensioning process to form a transverse and longitudinal bidirectional prestressing stress field, and the two prestressed steel bars 4 are treated without bonding at the joint interface in the pier body 2 to adapt to the controllable rotation at the joint; the two ends of the prestressed steel bars 4 are respectively anchored on the anchor plates in the pier top cap beam 3 and the foundation pedestal 1, and prestressing is applied to the prestressed steel bars 4 by a super-tensioning process.

[0032] The equation of the preset parabola is:

[0033]

[0034] Among them, e(x) is the eccentricity; e is the maximum eccentricity; h is half of the height of the swing pier; and x represents the position of the prestressed steel bar in the pier height direction.

[0035] The bending moment equation is derived as:

[0036] M=N·e(x)

[0037] Where, M is the equivalent bending moment; N is the prestress; and e(x) is the eccentricity.

[0038] The equivalent uniformly distributed load within the span is:

[0039]

[0040] Among them, q is the equivalent uniformly distributed load; M is the equivalent bending moment; N is the prestressing force; e is the maximum eccentricity; h is half the height of the swing pier; x represents the position of the prestressed steel bar in the pier height direction; d is the differential symbol, which means differential operation or derivation.

[0041] The construction method includes the following steps:

[0042] S1: During the concrete pouring stage of the foundation cap 1 and the pier body 2, a high-strength corrugated sleeve with a preset parabolic shape is pre-embedded along the axis of the pier. The corrugated sleeves are arranged continuously. The inner diameter of the corrugated sleeve is 20-30 mm larger than the diameter of the prestressed steel bar 4. The spacing between adjacent corrugated sleeves is not less than 5 times the diameter of the prestressed steel bar 4.

[0043] S2: An anchor plate is fixedly installed in the foundation pedestal 1, and an adjustable anchor plate is installed in the pier top cap beam 3. The anchor plate adopts a 40mm thick Q345 steel plate. A trumpet-shaped guide hole corresponding to the prestressed steel bar 4 is arranged on the anchor plate, and a wear-resistant nylon bushing is arranged on the inner wall of the guide hole;

[0044] S3: After the prestressed steel bar 4 is installed in the corrugated casing, the intelligent tensioning system is used to implement graded tensioning: first, 10% σ con (σ con To design the tension control stress) pre-tightening force, eliminate the gap between the steel strands and formally tension: load to 105%σ in three levels con Each level holds the load for 5 minutes and then drops to 100%σ con locking.

[0045] According to the present invention, the displacement curves of the top and bottom of the pier and the prestressing time history curve of the swing pier under the impact load are simulated and compared respectively for the arrangement of the straight prestressed tendons and the curved prestressed tendons of the present invention. Figure 6-9 ,

[0046] Among them, the calculation of shear recovery moment of linear reinforcement is:

[0047] u=2b-2Rsin(α-θ)

[0048] v=2Rcos(α-θ)-2h

[0049]

[0050]

[0051] M z =F 1z [(v+2h)-(be)sinθ]+F 2z [(v+2h)-(b+e)sinθ]+(N 1z +N 2z )(2b-u)

[0052] Among them, u is the maximum horizontal sliding distance of the swing pier; v is the vertical lifting height of the main beam; h is half of the height of the swing pier; b is half of the cross-sectional width of the swing pier; θ is the rotation angle generated during the movement of the swing pier; R is half of the diagonal length of the swing pier, that is, R 2 =h2 +b 2 ; h1 is the length of the prestressed tendon in the cap section; L oz represents the initial length of the linear prestressed tendon; E is the elastic modulus of the prestressed tendon; A is the cross-sectional area of ​​the prestressed tendon; N0 is the initial prestress of the prestressed tendon; N 1z 、N 2z are the prestress of the two straight prestressed tendons during the movement; F 1z 、F 2z are the equivalent restoring forces generated by two straight prestressed tendons in the horizontal direction; M z is the equivalent restoring moment of the linear prestressed tendon.

[0053] Calculation of shear recovery moment of curved reinforcement:

[0054] u=2b-2Rsin(α-θ)

[0055] v=2Rcos(α-θ)-2h

[0056]

[0057] M x =F 1x [(v+2h)-(be)sinθ]+F 2x [(v+2h)-(b+e)sinθ]+(N 1x +N 2x )(2b-u)+(q 2x hq 1x h)h

[0058] Because, L 0x ≈L 0z , v+2h>>h1, so:

[0059] M x -M z =(q 2x hq 1x h)h>0

[0060] Among them, u is the maximum horizontal sliding distance of the swing pier; v is the vertical lifting height of the main beam; h is half of the height of the swing pier; b is half of the cross-sectional width of the swing pier; θ is the rotation angle generated during the movement of the swing pier; R is half of the diagonal length of the swing pier, that is, R 2 =h 2 +b 2 ; h1 is the length of the prestressed tendon in the pedestal section; N0 is the initial prestress of the prestressed tendon; L ox represents the initial length of the curved prestressed tendon; L ozrepresents the initial length of the linear prestressed tendon; E is the elastic modulus of the prestressed tendon; A is the cross-sectional area of ​​the prestressed tendon; N 1x 、N 2x are the prestress of the two curved prestressed tendons during the movement; F 1x 、F 2x are the equivalent restoring forces generated by the two curved prestressed tendons in the horizontal direction; q 1x ,q 2x are the equivalent uniformly distributed loads of the two curved prestressed tendons; M z is the equivalent restoring moment of the linear prestressed tendon; M x is the equivalent restoring moment of the curved prestressed tendons.

[0061] That is, curved reinforcement improves the recovery moment.

[0062] After stress analysis, the bending recovery capacity of prestressed tendons is:

[0063]

[0064] Where, u is the maximum horizontal sliding distance of the swing pier; h is half of the height of the swing pier; b is half of the cross-sectional width of the swing pier; N 1x 、N 2x are the prestress of the two curved prestressed tendons during the movement; q 1x ,q 2x are the equivalent uniformly distributed loads of the two curved prestressed tendons; N 1z 、N 2z They are the prestress of the two linear prestressed tendons during the movement.

[0065] Therefore, the shear resistance of the curved reinforcement is excellent and does not affect the bending resistance of the pier. Figure 6-Figure 9 Based on the LS-DYNA platform, simulation and comparison found that the curved arrangement can generate effective prestress in the span of the rocking column without affecting the seismic performance, with good shear impact resistance and low peak slip. The ability of the pier to reset after impact is about 25.6% higher than that of the straight reinforcement.

[0066] Finally, it should be noted that the above preferred 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 through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A new type of swing self-resetting bridge pier with prestressed tendons arranged in a curve, characterized in that: Two prestressed steel bars arranged in a preset parabolic shape are embedded in the pier. The two prestressed steel bars are symmetrically arranged about the central axis of the pier cross section. The prestressed steel bars are arranged through the pier body by a post-tensioning process to form a transverse and longitudinal bidirectional prestressing force field. The prestressed steel bars are treated without bonding at the joint interface in the pier body.

2. The new type of swing self-resetting bridge pier with curved prestressed tendons according to claim 1 is characterized by: The equation of the preset parabola is: Among them, e(x) is the eccentricity; e is the maximum eccentricity; h is half of the height of the swing pier; and x represents the position of the prestressed steel bar in the pier height direction.

3. The new type of swing self-resetting bridge pier with curved prestressed tendons according to claim 2 is characterized by: The bridge pier includes a foundation cap, a pier body and a pier top cap beam which are fixedly connected in sequence from bottom to top. The prestressed steel bars are arranged to penetrate the pier body by a post-tensioning process. Both ends of the prestressed steel bars are anchored to anchor plates in the pier top cap beam and the foundation cap respectively, and prestressing is applied to the prestressed steel bars by a super-tensioning process.

4. The new type of swing self-resetting bridge pier with prestressed tendons arranged in a curve according to claim 3 is characterized by: The construction method of the self-resetting bridge pier comprises the following steps: S1: During the concrete pouring stage of the foundation cap and the pier body, a high-strength corrugated sleeve with a preset parabolic shape is pre-embedded along the axis of the pier. The corrugated sleeves are arranged continuously. The inner diameter of the corrugated sleeve is 20-30mm larger than the diameter of the prestressed steel bar. The spacing between adjacent corrugated sleeves is not less than 5 times the diameter of the prestressed steel bar. S2: An anchor plate is fixedly installed in the foundation cap, and an adjustable anchor plate is installed in the pier cap beam, wherein the anchor plate is provided with a trumpet-shaped guide hole corresponding to the prestressed steel bar, and the inner wall of the guide hole is provided with a wear-resistant nylon bushing; S3: After the prestressed steel bars are installed in the corrugated sleeve, the intelligent tensioning system is used to implement graded tensioning: first, 10% σ con Pre-tightening force, eliminating the gap between steel strands Formal tensioning: Loading in three levels to 105%σ con Each level holds the load for 5 minutes and then drops to 100%σ con Lock; where σ con To design tension control stress.

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