A lower-layer composite structure and design method of a novel double-deck plate-truss composite rigid-frame bridge

Abstract

The present invention relates to a combined structure for the lower layer of a new double - layer plate - truss composite rigid - frame bridge. The lower chord of the steel truss beam extends into the concrete of the 0# block, and an end bearing plate is provided at the end of the lower chord. A number of shear studs are provided on the lower chord extending into the concrete of the 0# block. Adjacent end bearing plates are connected by a combination of permanent and temporary components. The adjacent lower chords in the transverse direction of the bridge are connected by a lower - layer steel bottom plate and a lower cross - beam. The lower cross - beam is embedded in the concrete of the 0# block. The lower chord is filled with lower - chord filling concrete. A lower - layer concrete slab is cast on the lower - layer steel bottom plate, and the lower - layer concrete slab is connected to the concrete of the 0# block. The present invention effectively reduces the stress level of the lower chord, improves the stress transfer mechanism at the interface between the lower chord and the concrete of the 0# block. By reducing the compressive stress level of the steel structure, the risk of local buckling of the steel structure is eliminated, and the overall stability of the lower part of the steel truss beam is improved. By setting up the combination of permanent and temporary components, the accuracy, safety and convenience of the construction of the 0# block are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of bridges, in particular to a lower layer composite structure and design method of a novel double - layer plate - truss composite rigid - frame bridge. Background Art

[0002] Aiming at the problems of poor tensile performance of concrete and large self - weight of concrete beams, the steel - concrete composite structure gives full play to the tensile performance of steel and the compressive performance of concrete, and at the same time reduces the self - weight of the structure, which is beneficial to the seismic resistance of the structure in the near - fault strong earthquake area. When the existing steel - concrete composite structure is used in the novel double - layer plate - truss composite rigid - frame bridge, it has the following disadvantages:

[0003] 1. The force - transfer reliability at the joint between the lower chord of the steel truss beam and the concrete of the 0# block needs to be improved. Since the lower chord embedded in the concrete is longitudinally disconnected at the 0# block position, the pressure needs to be fully transferred to the concrete. There is a sudden change in the cross - section of the joint interface between the lower chord of the steel truss beam and the concrete of the 0# block, and the lower chord is under large compression. The uneven stress of the steel structure plate members leads to local buckling, affecting the structural safety.

[0004] 2. The lower chord near the 0# block bears a large pressure. Under the influence of manufacturing errors and residual stresses caused by component processing, it is easy to cause local or overall buckling of the lower chord, affecting the structural safety.

[0005] 3. Due to the discontinuous longitudinal force - transfer of the lower chord at the 0# block part, the 0# block of the steel truss needs precise positioning and fixation during construction erection, and there is a risk of affecting the operation safety of the completed bridge due to insufficient construction accuracy of the bridge structure.

[0006] Therefore, it is necessary to propose a lower layer composite structure of a novel double - layer plate - truss composite rigid - frame bridge to solve the above problems. Summary of the Invention

[0007] The purpose of the present invention is to provide a lower layer composite structure and design method of a novel double - layer plate - truss composite rigid - frame bridge in view of the problems existing in the prior art, such as unreasonable force - transfer mechanism, uneven stress distribution, potential local buckling, and high construction difficulty at the joint between the lower chord of the 0# block of the novel double - layer plate - truss composite rigid - frame bridge and the concrete.

[0008] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0009] In a first aspect, the present invention provides a novel lower-layer composite structure of a double-deck plate-truss composite rigid-frame bridge. The lower chord of the steel truss girder extends into the concrete of the 0# block, and an end bearing plate is provided at the end of the lower chord. A plurality of shear studs are provided on the lower chord extending into the concrete of the 0# block. The adjacent two end bearing plates are connected by a permanent-temporary combined component. The adjacent lower chords in the transverse direction of the bridge are connected by a lower-layer steel bottom plate and a lower cross beam. The lower cross beam is embedded in the concrete of the 0# block. The lower chord is filled with lower-chord filling concrete, and a lower-layer concrete slab is cast on the lower-layer steel bottom plate. The lower-layer concrete slab is connected to the concrete of the 0# block.

[0010] By adopting the novel lower-layer composite structure of the double-deck plate-truss composite rigid-frame bridge of the present invention, the transverse stability of the segment and the connection with the concrete of the 0# block are ensured by setting the lower-layer steel bottom plate and the lower cross beam. The axial force of the lower chord is ensured to be uniformly and continuously transmitted in the concrete by the shear studs. The geometric uniform transition of the interface between the lower chord and the 0# block is achieved by setting the lower-chord filling concrete. Most of the pressure of the lower chord is ensured to be transmitted from the concrete (the lower-layer concrete slab) to the 0# block, effectively reducing the stress level of the lower chord, greatly improving the stress transmission mechanism at the interface between the lower chord and the concrete of the 0# block, reducing the compressive stress level of the steel structure, eliminating the risk of local buckling of the steel structure, and improving the overall stability of the lower part of the steel truss girder. The accuracy, safety and convenience of the construction of the 0# block are improved by setting the permanent-temporary combined component.

[0011] As a preferred technical solution of the present invention, a gusset plate is provided on the end bearing plate, and the permanent-temporary combined component and the gusset plate are connected by bolts.

[0012] As a preferred technical solution of the present invention, the shear studs are arranged in an array.

[0013] As a preferred technical solution of the present invention, after the steel truss girder is closed, the lower-chord filling concrete is poured into the lower chord.

[0014] As a preferred technical solution of the present invention, after pouring the lower-chord filling concrete, the lower-layer concrete slab is cast on the lower-layer steel bottom plate.

[0015] As a preferred technical solution of the present invention, the lower-layer concrete slab and the concrete of the 0# block are connected by embedded steel bars.

[0016] In a second aspect, the present invention further provides a design method for the novel lower-layer composite structure of a double-deck plate-truss composite rigid-frame bridge, which is used to design the novel lower-layer composite structure of a double-deck plate-truss composite rigid-frame bridge as described in any one of the above. The design method includes the following steps:

[0017] S1. Based on the internal force analysis of the full bridge, determine the pressure of the lower chord for pouring the filling concrete of the lower chord, and conduct a check calculation for the overall instability of the component to preliminarily determine the thickness of the lower concrete slab.

[0018] S2. According to the results of the local detailed stress analysis, analyze the pressure transfer ratio of the lower chord and the lower concrete slab, and further determine the thickness of the lower concrete slab.

[0019] S3. Considering the force transfer uniformity between the lower chord and the concrete of the 0# block, determine the structure of the joint part of the lower concrete slab.

[0020] S4. Considering the force transfer law in the area of the lower chord extending into the concrete of the 0# block, determine the spacing of the shear studs of the lower chord at this part.

[0021] S5. According to the load conditions during the construction of the 0# block steel truss segment, determine the structure and dimensions of the permanent-temporary combined component during the construction process.

[0022] Adopting the design method of the lower layer composite structure of the novel double-deck plate-truss composite rigid frame bridge of the present invention, guided by reasonable force and uniform force transfer, the structure and dimensions of the lower concrete slab, the force transfer structure layout of the lower chord, and the structure and dimensions of the permanent-temporary combined component are determined successively, so that under the action of normal forces, the compressive stress levels of the lower chord and the lower steel bottom plate at the steel-concrete joint part below the 0# block are significantly reduced, the force transfer at the joint section between the lower chord and the 0# block is reasonable and uniform, the stress concentration range is reduced, during the construction process, the steel-concrete joint part below the 0# block can improve the installation accuracy during the assembly of the 0# block steel truss segment, and the 0# block concrete provides temporary support for the 0# block steel truss segment before reaching the setting period.

[0023] In the third aspect, the present invention also provides a bridge, including the lower layer composite structure of the novel double-deck plate-truss composite rigid frame bridge as described in any one of the above.

[0024] To sum up, due to the adoption of the above technical solutions, the beneficial effects of the present invention are:

[0025] 1. For the lower-layer composite structure of a novel double-deck plate-truss composite rigid frame bridge described in the present invention, the lateral stability of the segment and the connection with the 0# block concrete are ensured by setting the lower steel bottom plate and the lower cross beam. The axial force of the lower chord is ensured to be uniformly and continuously transmitted in the concrete by the shear studs. The geometric transition at the interface between the lower chord and the 0# block is made uniform by setting the concrete filled in the lower chord. Most of the pressure of the lower chord is ensured to be transmitted from the concrete (the lower concrete slab) to the 0# block by setting the lower concrete slab, effectively reducing the stress level of the lower chord, greatly improving the stress transfer mechanism at the interface between the lower chord and the 0# block concrete, reducing the compressive stress level of the steel structure, eliminating the risk of local buckling of the steel structure, improving the overall stability of the lower part of the steel truss beam, and improving the accuracy, safety and convenience of the construction of the 0# block by setting the permanent-temporary combined components;

[0026] 2. For the design method of the lower-layer composite structure of a novel double-deck plate-truss composite rigid frame bridge described in the present invention, guided by reasonable force and uniform force transmission, the structure and size of the lower concrete slab, the force transmission structure layout of the lower chord, and the structure and size of the permanent-temporary combined components are determined in sequence, so that the compressive stress levels of the lower chord and the lower steel bottom plate at the steel-concrete joint at the lower part of the 0# block are significantly reduced under the action of normal forces, the force transmission at the interface between the lower chord and the 0# block is reasonable and uniform, the stress concentration range is reduced, the installation accuracy during the assembly of the 0# block steel truss segment can be improved at the steel-concrete joint at the lower part of the 0# block during the construction process, and temporary support can be provided for the 0# block steel truss segment before the 0# block concrete reaches the hardening period. Description of the Drawings

[0027] Figure 1 It is a schematic longitudinal sectional view from outside to inside at the lower part of the 0# block of a novel double-deck plate-truss composite rigid frame bridge;

[0028] Figure 2 It is a schematic longitudinal sectional view from inside to outside at the lower part of the 0# block of a novel double-deck plate-truss composite rigid frame bridge;

[0029] Figure 3 It is a schematic plan projection view of the lower chord joint section at the lower part of the 0# block of a novel double-deck plate-truss composite rigid frame bridge.

[0030] Markings in the figure: 1-0# block concrete, 2-lower chord, 3-lower steel bottom plate, 4-lower concrete slab, 5-concrete filled in the lower chord, 6-permanent-temporary combined component, 7-bolt, 8-end bearing plate, 9-lower cross beam, 10-shear stud. Detailed Embodiments

[0031] The present invention will be described in detail below with reference to the accompanying drawings.

[0032] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] Embodiment 1

[0034] As Figures 1 to 3 shown, in a lower layer combined structure of a novel double - layer plate - truss composite rigid - frame bridge according to the present invention, the lower chord 2 of the steel truss beam extends into the 0# block concrete 1.

[0035] An end bearing plate 8 is provided at the end of the lower chord 2 extending into the 0# block concrete 1, and adjacent two end bearing plates 8 are connected by a permanent - temporary combined component 6; specifically, a gusset plate is provided on the end bearing plate 8, and the permanent - temporary combined component 6 and the gusset plate are connected by high - strength bolts 7. The illustrated permanent - temporary combined component 6 is a rod, a total of four, arranged along the four sides of a rectangular column and connected to the corresponding gusset plates on the end bearing plate 8. By connecting the discontinuous lower chords 2 through the permanent - temporary combined component 6, the accuracy and safety during the construction process are ensured.

[0036] A plurality of shear studs 10 are provided on the lower chord 2 extending into the 0# block concrete 1, and the shear studs 10 are arranged in an array. By means of the shear studs 10, the axial force of the lower chord 2 is ensured to be uniformly and continuously transmitted in the concrete.

[0037] Adjacent lower chords 2 in the transverse bridge direction are connected by a lower - layer steel bottom plate 3 and a lower cross - beam 9, and the lower cross - beam 9 is embedded in the 0# block concrete 1. By providing the lower - layer steel bottom plate 3 and the lower cross - beam 9, the transverse stability of the segment and the connection with the 0# block concrete 1 are ensured.

[0038] After the steel truss beam is closed, the lower - chord filling concrete 5 is poured into the lower chord 2, and then the lower - layer concrete slab 4 is cast on the lower - layer steel bottom plate 3. The lower - layer concrete slab 4 is connected to the 0# block concrete 1 through embedded steel bars. By providing the lower - chord filling concrete 5, a uniform transition at the interface of the 0# block is achieved; by providing the lower - layer concrete slab 4, it is ensured that most of the pressure of the lower chord 2 is transmitted to the 0# block by the concrete.

[0039] The lower - layer combined structure of a novel double - layer plate - truss composite rigid - frame bridge in this embodiment effectively reduces the stress level of the lower chord 2, improves the stress transfer mechanism at the interface between the lower chord 2 and the 0# block concrete 1. By reducing the compressive stress level of the steel structure, the risk of local buckling of the steel structure is eliminated, and the overall stability of the lower part of the steel truss beam is improved. By providing the permanent - temporary combined component 6, the accuracy, safety and convenience of the construction of the 0# block are improved.

[0040] Embodiment 2

[0041] As Figures 1 to 3 shown, a design method for the lower layer composite structure of a novel double - layer plate - truss composite rigid - frame bridge according to the present invention is used to design the lower layer composite structure of the novel double - layer plate - truss composite rigid - frame bridge as described in Embodiment 1. The design method includes the following steps:

[0042] S1. According to the internal force analysis of the whole bridge, determine the pressure of the lower chord 2 for pouring the filling concrete 5 of the lower chord, and carry out the overall buckling check of the component, and preliminarily determine the thickness of the lower layer concrete slab 4;

[0043] S2. Based on the local detailed stress analysis results, analyze the pressure transfer ratio of the lower chord 2 and the lower layer concrete slab 4, and further determine the thickness of the lower layer concrete slab 4;

[0044] S3. Considering the force - transfer uniformity between the lower chord 2 and the 0# block concrete 1, determine the structure of the joint part of the lower layer concrete slab 4;

[0045] S4. Considering the force - transfer law in the area of the lower chord 2 extending into the 0# block concrete 1, determine the spacing of the shear studs 10 of the lower chord 2 at this part;

[0046] S5. According to the load conditions during the construction of the 0# block steel truss section, determine the structure and dimensions of the permanent - temporary combined component 6 during the construction process.

[0047] The design method for the lower layer composite structure of a novel double - layer plate - truss composite rigid - frame bridge described in this embodiment is guided by reasonable force - bearing and uniform force - transfer. By determining the structure and dimensions of the lower layer concrete slab 4, the force - transfer structure layout of the lower chord 2, and the structure and dimensions of the permanent - temporary combined component 6 in sequence, the compressive stress levels of the lower chord 2 and the lower layer steel bottom plate 3 at the steel - concrete joint part below the 0# block under normal forces are significantly reduced. The force - transfer at the joint section between the lower chord 2 and the 0# block is reasonable and uniform, the stress concentration range is reduced, and during the construction process, the steel - concrete joint part below the 0# block can improve the installation accuracy during the assembly of the 0# block steel truss section, and provide temporary support for the 0# block steel truss section before the 0# block concrete reaches its setting period.

[0048] Embodiment 3

[0049] A bridge according to the present invention includes the lower layer composite structure of the novel double - layer plate - truss composite rigid - frame bridge as described in Embodiment 1.

[0050] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. Design method for lower layer composite structure of a new double - layer plate - truss composite rigid - frame bridge Characterized in that For designing the lower layer composite structure of a new double - layer plate - truss composite rigid - frame bridge, the lower chord rod (2) of the steel truss girder extends into the 0# block concrete (1), and an end bearing plate (8) is provided at the end of the lower chord rod (2). A number of shear studs (10) are provided on the lower chord rod (2) extending into the 0# block concrete (1). The adjacent two end bearing plates (8) are connected by a permanent - temporary combined component (6). The adjacent lower chord rods (2) in the transverse bridge direction are connected by a lower - layer steel bottom plate (3) and a lower cross - beam (9). The lower cross - beam (9) is embedded in the 0# block concrete (1). The lower chord rod (2) is filled with lower chord rod filling concrete (5). The lower - layer concrete slab (4) is cast on the lower - layer steel bottom plate (3), and the lower - layer concrete slab (4) is connected to the 0# block concrete (1); This design method includes the following steps: S1. According to the internal force analysis of the whole bridge, determine the pressure of the lower chord rod (2) filled with the lower chord rod filling concrete (5), and carry out the overall buckling check of the component to preliminarily determine the thickness of the lower - layer concrete slab (4); S2. Based on the local detailed stress analysis results, analyze the pressure transfer ratio between the lower chord rod (2) and the lower - layer concrete slab (4), and further determine the thickness of the lower - layer concrete slab (4); S3. Considering the force - transfer uniformity between the lower chord rod (2) and the 0# block concrete (1), determine the structure of the joint part of the lower - layer concrete slab (4); S4. Considering the force - transfer law in the area of the lower chord rod (2) extending into the 0# block concrete (1), determine the spacing of the shear studs (10) of the lower chord rod (2) at this part; S5. According to the load conditions during the construction of the 0# block steel truss segment, determine the structure and size of the permanent - temporary combined component (6) during the construction process.

2. The design method for the lower layer composite structure of the new double - layer plate - truss composite rigid - frame bridge according to claim 1 Characterized in that A gusset plate is provided on the end bearing plate (8), and the permanent - temporary combined component (6) and the gusset plate are connected by bolts (7).

3. The design method for the lower layer composite structure of the new double - layer plate - truss composite rigid - frame bridge according to claim 1 Characterized in that The shear studs (10) are arranged in an array.

4. The design method for the lower layer composite structure of the new double - layer plate - truss composite rigid - frame bridge according to claim 1 Characterized in that After the steel truss girder is closed, the lower chord rod filling concrete (5) is poured into the lower chord rod (2).

5. The design method for the lower layer composite structure of the new double - layer plate - truss composite rigid - frame bridge according to claim 1 Characterized in that After pouring the lower chord rod filling concrete (5), the lower - layer concrete slab (4) is cast on the lower - layer steel bottom plate (3).

6. The design method for the lower layer composite structure of the new double - layer plate - truss composite rigid - frame bridge according to any one of claims 1 - 4 Characterized in that The lower - layer concrete slab (4) and the 0# block concrete (1) are connected by embedded steel bars.

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