Prestressed seamless multi-span curved bridge construction structure and construction method

Abstract

The present application relates to a kind of prestressed seamless multi-span curved bridge construction structure and construction method, belong to prestressed seamless curved bridge technical field, the construction structure of the present application includes the temporary support structure being arranged between main girder and lower structure, temporary support structure includes recess channel, roller, turntable and bottom steel plate;The roller is placed in recess channel transversely, can slide along recess channel, and the diameter of roller is greater than the groove height of recess channel, and the length of roller is less than the groove width of recess channel;The turntable is arranged below recess channel.The present application uses roller with turntable as temporary support structure at the abutment of seamless curved bridge, turntable can rotate with the change of angle, roller can roll with the change of displacement, to avoid the oblique displacement between main girder and lower structure with a certain angle when tensioning prestressed tendon.

Description

Technical Field

[0001] This invention belongs to the field of prestressed seamless curved bridge technology, specifically, it relates to a construction structure and construction method for a prestressed seamless multi-span curved bridge. Background Technology

[0002] A bridge with a continuous superstructure within the end range of the two approach slabs and no expansion joints is called a jointless bridge. In multi-span bridges, if the main beams of adjacent spans are continuous structures, the bridge deck is naturally continuous, and there are no expansion joints or expansion devices between adjacent spans, it is called a seamless bridge. Seamless bridges can be classified into several different types. Based on the horizontal and vertical alignment of the bridge, seamless bridges can be divided into orthogonal seamless bridges, skew seamless bridges, and seamless bridges with horizontal curves (seamless curved bridges). The most common classification of seamless bridges is based on the abutments used, dividing them into three main forms: integral bridges, semi-integral bridges, and extended deck bridges.

[0003] With the development of economic construction, planar curved bridges are widely used in modern bridges. However, the structure of a planar curved bridge is subject to complex stresses, including bending moment, shear force, large torque, and warping moment, making it prone to defects such as cracks and support slippage. The deformation characteristics of curved bridges are unfavorable to jointed bridges but become an advantage of seamless bridges. Under the influence of temperature, the deformation of the structure along the axial direction can be converted into deformation in the sag direction, making it possible to construct seamless curved bridges with lengths far exceeding those of straight seamless bridges.

[0004] During prestressing of the seamless curved bridge, both the radial and longitudinal displacements of the main girder change. The main girder initially deforms along angle 'a', and after a period of time, it begins to deform along angle 'b' (as shown in the attached figure). Figure 6 As shown in the figure, the displacement of the main beam at different times along different oblique angles is called oblique displacement. The longitudinal bridge displacement, radial displacement, and oblique displacement between the main beam and the substructure all affect the stability of the main beam structure. For integral seamless bridges, utility model patent CN202122041675.9 mentions a construction structure for integral bridge abutments, which uses temporary supports including I-beams and steel plates welded to the upper and lower ends of the I-beams, so that the anchor bars in the end beams are slidably connected to the temporary supports, avoiding the displacement of the abutments and pile foundations when the main beam is prestressed. However, this structure can only slide in the longitudinal direction of the main beam and cannot solve the impact of radial displacement on the stability of the main beam structure. Summary of the Invention

[0005] The effect of longitudinal prestressing tendons in prestressed seamless curved bridges is mainly reflected in the influence of axial normal stress. Applying prestress increases the compressive stress on the top plate of the main beam, thereby enhancing the effective prestress of the seamless curved bridge. During construction, different prestressing tensioning sequences will cause different structural responses. By comparing different prestressing tendon tensioning sequences, the prestressing tensioning sequence that can enhance the effective prestress can be determined. Addressing the problems of seamless curved bridges mentioned in the background art, this invention provides a construction structure and method for prestressed seamless multi-span curved bridges. Through the structural design of a temporary support structure, and by placing this temporary support structure between the substructure and the main beam of the prestressed seamless multi-span curved bridge, the turntable can rotate with the change of the oblique displacement angle of the main beam, and the rollers can roll with the change of the oblique displacement of the main beam. This avoids oblique displacement between the main beam and the substructure during prestressing tendon tensioning, ensuring the stability of the main beam structure.

[0006] Based on this, the first objective of the present invention is to provide a temporary support structure that can eliminate the oblique displacement between the main beam and the substructure, and the temporary support structure can also improve the effective prestress during the construction of a prestressed seamless curved bridge; the second objective of the present invention is to provide an application of the temporary support structure in improving the prestress of the construction structure of a seamless multi-span curved bridge; the third objective of the present invention is to provide a prestressed seamless multi-span curved bridge construction structure including the temporary support structure; and the fourth objective of the present invention is to provide a construction method for a prestressed seamless multi-span curved bridge.

[0007] The prestressed seamless multi-span curved bridge construction structure includes a main beam, a substructure, and a temporary support structure. The temporary support structure includes a groove, rollers, and a turntable. The rollers are placed laterally within the groove, allowing them to slide along it. The diameter of the rollers is greater than the groove height, and the length of the rollers is less than the groove width. The turntable is positioned below the groove and includes an inner ring, an upper outer ring, and a lower outer ring. The upper and lower outer rings are respectively fitted onto the upper and lower end faces of the inner ring, and the contact surfaces between the upper and lower outer rings and the inner ring are respectively provided with an upper row of rotating beads and a lower row of rotating beads. The bottom plate of the groove is welded parallel to the top surface of the upper outer ring; the bottom steel plate is welded parallel to the bottom surface of the lower outer ring. The temporary support structure is positioned between the main beam and the substructure.

[0008] Furthermore, the groove includes a base plate and guide slides vertically fixed to both sides of the upper surface of the base plate; the diameter of the roller is greater than the height of the guide slides; the roller is placed horizontally in the groove; gaps are reserved between the two ends of the roller and the two guide slides; the roller can roll in the groove and, under the limiting action of the guide slides at both ends, always rolls along the guide slides.

[0009] Furthermore, the substructure includes cast-in-place piles, a pile cap, and abutment body that are fixed together from bottom to top; the temporary support structure is set between the abutment body and the main beam.

[0010] The above-mentioned prestressed seamless multi-span curved bridge construction structure is applied to improve the effective prestress in the construction of seamless curved bridges.

[0011] The aforementioned temporary support structure is used to enhance the effective prestress in the construction of seamless curved bridges.

[0012] The construction method for the prestressed seamless multi-span curved bridge uses any of the aforementioned temporary support structures.

[0013] Furthermore, the construction method is characterized in that, during the prestressing of the seamless curved bridge, the inner and outer prestressing tendons are tensioned simultaneously.

[0014] The construction method for the prestressed seamless multi-span curved bridge structure includes the following steps:

[0015] S1, the construction of cast-in-place piles, pile caps and abutment bodies will be carried out first.

[0016] S2, weld the bottom steel plate to the top steel reinforcement of the abutment body.

[0017] S3. Based on the initial angle between the main beam shortening direction and the abutment after the main beam is constructed, obtained from the finite element simulation calculation of the seamless curved bridge, manually rotate the groove channel to drive the upper outer ring to rotate, so that the roller is perpendicular to the beam shortening direction.

[0018] S4, pour the beam end, and tension the prestressing tendons in the order of simultaneous tensioning of the inner and outer prestressing tendons. During the tensioning process, the main beam shortens along the oblique displacement, which drives the roller to roll along the oblique displacement of the main beam. The rolling of the roller drives the upper outer ring welded to the groove to rotate, so that the turntable rotates with the change of the oblique angle of the main beam.

[0019] S5, the formwork is erected and concrete is poured for the back section of the platform.

[0020] S6, the abutment and beam end are now fixed together.

[0021] The beneficial effects of this invention are:

[0022] This invention employs a roller with a turntable as a temporary support structure at the abutment of a seamless curved bridge. The turntable can rotate with the change of the oblique angle of the main beam, and the roller can roll with the change of oblique displacement, thereby avoiding the oblique displacement between the main beam and the substructure when tensioning the prestressing tendons. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the temporary support structure of the present invention;

[0024] Figure 2 yes Figure 1 Side view;

[0025] Figure 3 This is the present invention. Figure 2 Enlarged view of a portion at point A;

[0026] Figure 4 This is an exploded view of the turntable structure of the present invention;

[0027] Figure 5 This is a front view of the seamless curved bridge abutment of the present invention;

[0028] Figure 6 This is a schematic diagram of the oblique displacement of a seamless curved bridge;

[0029] Figure 7 This is a diagram illustrating the stress along the centerline of the bridge when temporary supports are installed at different locations.

[0030] Figure 8 The diagram shows the oblique deformation of a seamless curved bridge (magnification of 1000x).

[0031] Figure 9 It is a diagram showing the longitudinal and radial deformation curves of the top and bottom plates of a seamless curved bridge along the centerline of the bridge.

[0032] Figure 10 This is a graph showing the change in the angle of oblique sliding at the bottom of the beam ends on both sides of the main beam over time during the prestressing tensioning process;

[0033] Figure 11 It is the stress along the centerline of the top slab in the longitudinal direction of the bridge when the inner and outer steel bars are tensioned simultaneously;

[0034] Figure 12 It is a sectional view of the upper outer ring or the lower outer ring;

[0035] Figure 13 These are the on-site construction drawings of the support structure of this invention;

[0036] Remark:

[0037] Figure 7 In the figure, (a) shows the longitudinal stress on the top surface, and (b) shows the longitudinal stress on the bottom surface.

[0038] Figure 8 In the figures, (a) shows the prestressing tendons being tensioned together; (b) shows the prestressing tendons being tensioned in the order of middle-left-right; (c) shows the prestressing tendons being tensioned in the order of inner-middle-outer; and (d) shows the prestressing tendons being tensioned in the order of outer-middle-inner.

[0039] In the diagram, 1 is the turntable, 2 is the base plate, 3 is the roller, 4 is the guide slide plate, 5 is the bottom steel plate, 6 is the parallel weld, 101 is the upper outer ring, 102 is the lower outer ring, 103 is the inner ring, 104 is the upper row of rotating beads, 105 is the lower row of rotating beads, 106 is the groove, 201 is the temporary support structure, 202 is the beam end, 203 is the abutment body, 204 is the pier cap, 205 is the cast-in-place pile, and 206 is the rear cast-in-place section of the abutment. Detailed Implementation

[0040] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are all within the scope of protection of this invention.

[0041] To illustrate the present invention more clearly, the following embodiments will be described in detail. Example 1

[0042] A temporary support structure includes a groove channel, a roller 3, a turntable 1, and a bottom steel plate 5. The groove channel is a U-shaped channel structure, including a base plate 2 and guide slides 4 vertically fixed to both sides of the upper end surface of the base plate 2.

[0043] The roller 3 is perpendicular to and laterally positioned within the groove, aligned with the guide slide 4. Its diameter is greater than the height of the guide slide 4, and its length is slightly less than the vertical distance between the two guide slides 4. This design, where the roller 3's diameter is greater than the height of the guide slide 4, ensures that the bottom surface of the main beam contacts the roller 3 during use. The roller 3's length is slightly less than the two guide slides 4, meaning that gaps are pre-drilled between the roller 3 and each of the two guide slides 4. These gaps allow the roller 3 to roll within the groove and, under the limiting action of the guide slides 4 at both ends, to always roll along them. A baffle is also provided on the base plate 2, perpendicular to the guide slide 4 and positioned at both ends of the base plate 2. The baffle is not higher than the guide slide 4. The baffle prevents the roller 3 from rolling off the base plate 2 (Note: the baffle is omitted in the attached diagram to clearly show the connection between the base plate and the guide plate). The baffle's height is lower than the guide slide 4 to avoid affecting the rotation of the roller 3.

[0044] The turntable includes an inner ring 103, an upper outer ring 101, and a lower outer ring 102. The upper outer ring 101 and the lower outer ring 102 have the same structure, both being grooved rings with grooves 106. The grooves 106 of the upper outer ring 101 and the lower outer ring 102 are respectively fitted onto the upper and lower end faces of the inner ring 103, and the contact surfaces between the upper outer ring 101 and the lower outer ring 102 and the inner ring 103 are respectively provided with an upper row of rotating beads 104 and a lower row of rotating beads 105. The upper outer ring 101 and the lower outer ring 102 can rotate concentrically around the inner ring 103, and the arrangement of the upper row of rotating beads 104 and the lower row of rotating beads 105 can reduce rotational friction.

[0045] The bottom plate 2 of the recessed groove is welded parallel to the top surface of the upper outer ring 101; the bottom steel plate 5 is welded parallel to the bottom surface of the lower outer ring 102.

[0046] The structure of this invention can serve as a temporary support structure, positioned between the main beam and the substructure. When the seamless curved bridge experiences oblique displacement, the roller 3 rolls, causing a change in the force on the groove channel. This groove channel drives the upper outer ring 101 of the turntable to rotate. At this time, the lower outer ring 102 is welded and fixed to the bottom steel plate 5. The upper outer ring 101 and the lower outer ring 102 rotate relative to each other via the rotation of the upper row of rotating beads 104 and the lower row of rotating beads 105. During bridge construction, the structure supports the beam end of the main beam between it and the substructure, enabling it to withstand large radial loads, axial loads, and overturning loads, ensuring the stability of the construction structure while reducing the oblique displacement of the main beam and the substructure during construction.

[0047] The upper outer ring 101 and the lower outer ring 102 can be any structure capable of concentric rotation around the inner ring 103, for example, as shown in the attached figure. Figure 4 The grooved ring structure fits the upper and lower end faces of the inner ring 103, and the upper row of rotating beads 104 and the lower row of rotating beads 105 are constrained by the groove 106 and will not fall out of the groove 106. Example 2

[0048] A prestressed seamless multi-span curved bridge construction structure includes a main beam, a substructure, and the temporary support structure described in Example 1.

[0049] The substructure includes cast-in-place piles 205, a pile cap 204, and an abutment body 203, which are fixed from bottom to top. The temporary support structure is set between the abutment body 203 and the main beam. Specifically, the bottom steel plate 5 of the temporary support structure is welded to the top steel bar of the abutment body 203, and the roller 3 is in contact with the lower end face of the beam end 202 of the main beam. Example 3

[0050] A construction method for a prestressed seamless multi-span curved bridge, using the temporary support structure described in Example 1, includes the following steps:

[0051] S1, first carry out the construction of cast-in-place piles, pile caps and abutment bodies;

[0052] S2, weld the bottom steel plate 5 to the top steel bar of the abutment body;

[0053] S3. Based on the initial angle between the main beam's shortening direction and the abutment after the main beam construction is completed, obtained from the finite element simulation calculation of the seamless curved bridge, manually rotate the outer ring of the turntable connected to the groove channel to rotate the balls inside the turntable, making the rollers perpendicular to the beam's shortening direction.

[0054] S4, pour the beam end 202, and tension the prestressing tendons in the order of simultaneous tensioning of the inner and outer prestressing tendons. During the tensioning process, the main beam shortens along the oblique displacement, causing the rollers to roll along the oblique displacement of the main beam. The rollers drive the groove channel, which is welded to the outer ring of the turntable. The outer ring drives the rollers inside the turntable to rotate, thus causing the turntable to rotate with the change of the oblique angle of the main beam.

[0055] S5, the formwork for the back section 206 is erected and concrete is poured.

[0056] S6, the abutment and beam end are now fixed together.

[0057] Application Examples

[0058] Using the temporary support structure described in Example 1, a seamless curved bridge with a total span of 160m was constructed and installed according to the method in Example 3 (as shown in the attached site construction drawings). Figure 12 ).

[0059] Finite element analysis was conducted based on the actual engineering project. To determine the installation location of the temporary support structure, finite element analysis was performed on three working conditions: temporary supports only at the abutments, temporary supports at the abutments and secondary piers, and temporary supports at the abutments and all piers. The relationship between the top and bottom longitudinal stresses under the three working conditions was obtained through finite element analysis (see attached diagram). Figure 7 ).

[0060] Appendix Figure 7 In the context of bridge construction, "side-not-fixed" refers to the condition where temporary supports are only installed at the abutments; "side-plus-secondary-not-fixed" refers to the condition where temporary supports are installed at both the abutments and secondary piers; and "fully-not-fixed" refers to the condition where temporary supports are installed at both the abutments and all piers. (See attached...) Figure 7 It can be seen that there is no significant difference in the effective prestress of the bridge under the three working conditions. Considering the actual construction conditions, in order to facilitate construction, only temporary support structures need to be set at the abutments.

[0061] Numerical simulations were performed using finite element method (FEM) software to simulate four tensioning sequences: simultaneous tensioning of the prestressing tendons on both the inner and outer sides (full bridge tensioning and mid-span-left-right span tensioning), inner-middle-outer side, and outer-middle-inner side. Deformations are shown in the attached figure. Figure 8As shown in the attached figure, the longitudinal and radial deformations of the top and bottom plates of the seamless curved bridge along the bridge centerline are as follows. Figure 9 As shown in the attached figure, the angle of oblique movement changes with tensioning time. Figure 10 As shown.

[0062] Therefore, it can be concluded that the longitudinal displacement of the top and bottom slabs of the seamless curved bridge is almost the same under different prestressing tendon tensioning sequences. Regarding radial displacement and rotation angle, when the inner and outer prestressing tendons are tensioned simultaneously (i.e., all prestressing tendons are tensioned synchronously) and when tensioning is done in segments from the middle span to the left span to the right span, the radial displacement of the top and bottom slabs and the oblique angle of rotation of the bottom of the main beam at both ends are almost the same, with a maximum radial displacement of 0.76 mm and a maximum rotation angle of 3°. When the prestressing tendons are tensioned in the sequence of inner-middle-outer, the right end of the main beam always rotates counterclockwise, while the left end first rotates clockwise, and then rotates clockwise as the outer prestressing tendons are tensioned. Ultimately, the entire structure rotates counterclockwise, with the maximum radial displacement at the rightmost end of the bridge being 14.65 mm and the maximum rotation angle being 85.8° at the left end of the main beam when tensioning begins. When the prestressing tendons are tensioned in the order of outer side-middle-inner side, the right end of the main beam always rotates clockwise, while the left end first rotates counterclockwise. Then, with the tensioning of the inner prestressing tendons, the entire structure eventually rotates clockwise, with the maximum radial displacement at the rightmost end of the bridge being 15.37 mm and the maximum rotation angle being 92.2°.

[0063] Therefore, when tensioning prestressing in seamless curved bridges, it is recommended to tension the inner and outer prestressing tendons simultaneously (i.e., tension all prestressing tendons synchronously and tension them in sections of the middle span, left span, and right span), which can effectively reduce the radial displacement and oblique rotation angle of the main beam.

[0064] Based on the above conclusions, a numerical simulation was conducted on a prestressed seamless curved bridge using synchronous tensioning of inner and outer prestressing tendons. The difference in main beam stress was compared between bridges with this support device placed at the abutment and those with directly cast monolithic abutments. Figure 11 It can be seen that when all the prestressing tendons of the bridge are tensioned simultaneously, the compressive stress on the top plate of the main beam after using this sliding roller support device increases by up to 33.8% compared with the directly cast integral abutment, and by up to 22.1% compared with the single box girder sliding. When the prestressing tendons are tensioned in the order of middle span-left span-right span, the compressive stress on the top plate of the main beam after using this support device increases by up to 29.8% compared with the directly cast integral abutment, and by up to 24.2% compared with the unidirectional sliding shoe.

[0065] Finite element analysis showed that using this support device at the post-cast section of the seamless curved bridge abutment, and tensioning the prestressing tendons in a simultaneous inner and outer sequence, can increase the compressive stress on the main beam of the seamless curved bridge and improve the effective prestress of the seamless curved bridge. The overall structure of the turntable in Example 1 can also be replaced by a double-row spherical slewing bearing with varying diameters.

[0066] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended 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 to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A method for constructing a prestressed seamless multi-span curved bridge, characterized in that, Includes the following steps, S1, first carry out the construction of cast-in-place piles, pile caps and abutment bodies; S2, weld the bottom steel plate to the top steel reinforcement of the abutment body; S3. Based on the initial angle between the main beam shortening direction and the abutment after the main beam is constructed according to the finite element simulation calculation of the seamless curved bridge, manually rotate the outer ring of the turntable connected to the groove channel to make the ball inside the turntable rotate, which in turn drives the outer ring to rotate, so that the roller is perpendicular to the direction of beam shortening. S4, pour the beam end, and tension the prestressing tendons in the order of simultaneous tensioning of the inner and outer prestressing tendons. During the tensioning process, the main beam shortens along the oblique displacement, causing the roller to roll along the oblique displacement of the main beam. The rolling of the roller causes the upper outer ring welded to the groove to rotate, thereby causing the turntable to rotate with the change of the oblique angle of the main beam. During the tensioning of prestress, the inner and outer prestressing tendons are tensioned simultaneously. S5, erect formwork and pour concrete for the rear section of the abutment; S6, the abutment and beam end are now fixed together; The prestressed seamless multi-span curved bridge construction method described above corresponds to a prestressed seamless multi-span curved bridge construction structure including a main beam, a substructure, and a temporary support structure. The temporary support structure includes a groove, rollers, a turntable, and a bottom steel plate; the rollers are placed laterally within the grooves and can slide along them, with the roller diameter greater than the groove height and the roller length less than the groove width; the rollers are perpendicular to the direction of beam shortening. The turntable includes an inner ring, an upper outer ring, and a lower outer ring; the upper outer ring and the lower outer ring are respectively fitted onto the upper and lower end faces of the inner ring, and the contact surfaces of the upper outer ring and the lower outer ring with the inner ring are respectively provided with an upper row of rotating beads and a lower row of rotating beads; the upper outer ring and the lower outer ring can rotate concentrically around the inner ring respectively. The bottom plate of the groove is welded parallel to the top surface of the upper outer ring; the bottom steel plate is welded parallel to the bottom surface of the lower outer ring. The temporary support structure is set between the main beam and the substructure.

2. The construction method according to claim 1, characterized in that, The groove includes a base plate and guide slides fixed vertically to both sides of the upper surface of the base plate; the diameter of the roller is greater than the height of the guide slides; the roller is placed horizontally in the groove; gaps are reserved between the two ends of the roller and the two guide slides; the roller can roll in the groove and, under the limiting action of the guide slides at both ends, always rolls along the guide slides.

3. The construction method according to claim 1 or 2, characterized in that, The substructure includes, from bottom to top, cast-in-place piles, abutments, and abutment bodies; the temporary support structure is located between the abutment bodies and the main beams.

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