Template-free super large scale UHPC-CSW-NC combined bent cap and construction method

Abstract

The application discloses a kind of free template super large scale UHPC-CSW-NC combined bent cap structure and construction method, including the UHPC-CSW prefabricated combination shell with inner cavity, multiple middle cross partitions are distributed along its length direction in combination shell, and inner support frame is fixed between middle cross partition and combination shell, between adjacent two middle cross partitions, the periphery of combination shell, the top plate of combination shell, the two sides of middle cross partition are all provided with corrugated steel web, UHPC is poured between the two corrugated steel webs of middle cross partition, and middle cross partition is arranged above pier.The construction method thereof includes the following steps: installing CSW in factory without template, pouring UHPC, forming combination shell, then tensioning first group of prestressed beam;Then transport and hoist, pour inner cavity ordinary concrete.Compared with prior art, the bent cap of the application is free of template construction, has no influence on the site environment, has high bending and shear bearing capacity, the self-weight of the combination shell is relatively light, the steel frame is simple to manufacture, and the construction speed is fast.

Description

Technical Field

[0001] The present invention relates to the technical field of bridges, and in particular to a formwork-free ultra-large-scale UHPC-CSW-NC composite cap beam and a construction method. Background Art

[0002] The concept of prefabrication and assembly has penetrated into the field of bridge construction. Prefabricated assembly structures have obvious advantages such as beautiful appearance, good quality, good adaptability to traffic and environment, greatly shortened construction period, small concrete shrinkage and creep effects, easy control of lines, good driving conditions, safety, and environmental protection.

[0003] With the increasing demand for traffic under viaducts, large cantilever cap beam structures are increasingly being used. Large cantilever ordinary concrete cap beams are difficult to construct using prefabrication and hoisting due to their enormous size and heavy weight. Transportation and hoisting are inconvenient, and therefore, large cantilever ordinary concrete cap beams are often constructed using on-site casting or segmented prefabrication. On-site casting requires processes such as scaffolding installation, formwork erection, pouring, and maintenance. The construction steps are cumbersome and time-consuming, and the space under the cap beam is occupied for a long time, which has a significant negative impact on the surrounding environment. Segmented prefabrication has a small workload, a short construction period, and minimal traffic impact, but it still requires scaffolding to support the segmented cap beams, which has a certain negative impact on the site. Due to the segmented treatment, the long-term durability of the joints is affected, and the structural integrity is not strong.

[0004] Therefore, how to give full play to the advantages of prefabricated assembly structures during the construction of cap beams, reduce the energy consumption of on-site measures, reduce the amount of on-site construction work, and increase the construction speed has become a technical problem that needs to be solved urgently. Summary of the Invention

[0005] The present invention provides a formwork-free ultra-large-scale UHPC-CSW-NC composite cap beam and a construction method, which are used to solve the problems of high energy consumption, slow construction speed and low efficiency of existing cap beam construction site measures.

[0006] The present invention provides a formwork-free ultra-large-scale UHPC-CSW-NC composite cap beam, comprising a composite shell prefabricated from UHPC with an inner cavity, wherein a plurality of middle transverse diaphragms are distributed in the composite shell along its length direction, and an inner support frame is fixed between the middle transverse diaphragm and the composite shell and between two adjacent middle transverse diaphragms, and corrugated steel webs are provided on both sides of the composite shell, at both ends of the composite shell, at the top plate of the composite shell, and on both sides of the middle transverse diaphragm, UHPC is cast between the two corrugated steel webs of the middle transverse diaphragm, and casting holes and air vents are reserved on the top plate of the composite shell, the inner support frame comprises a transverse column and an oblique support column, two of the transverse columns are arranged up and down, the ends of the oblique support column are fixed to the ends of the upper transverse columns, and the two oblique support columns are distributed in a V-shape, the transverse columns and the oblique support columns are fixed to the composite shell, the inner cavity of the composite shell is cast with ordinary concrete, and the middle transverse diaphragm is arranged above the bridge pier.

[0007] Preferably, the thickness of the UHPC of the top plate is 6-10 cm, and the thickness of the UHPC of the bottom plate is 12-15 cm; the compressive strength of the UHPC of the combined shell is 120-150 MPa, and the tensile strength is 7-9 MPa.

[0008] Preferably, CSW is used as webs on both sides of the combined shell, and the CSW on both sides of the combined shell are made of steel plates with a thickness of 12-20 mm.

[0009] Preferably, the UHPC of the top plate, both ends of the combined shell, and the middle transverse partition all use CSW as a template, and the thickness of the CSW of the top plate, both ends of the combined shell, and the middle transverse partition is 2 to 4 mm.

[0010] Preferably, the outer walls at both ends of the combined housing are provided with flat steel plates.

[0011] Preferably, the transverse columns and diagonal bracing columns are angle steels or T-shaped steels.

[0012] Preferably, both ends of the lower transverse column are fixed to the combined shell through longitudinal angle steels, and the upper transverse column is fixed to the diagonal bracing column and the combined shell through longitudinal angle steels.

[0013] Preferably, a plurality of first shear nails are arranged on both the top plate and the bottom plate of the combined shell.

[0014] Preferably, two or three groups of prestressed bundles are provided inside the combined shell.

[0015] The present invention also provides a construction method for a formwork-free ultra-large-scale UHPC-CSW-NC composite cap beam, comprising the formwork-free ultra-large-scale UHPC-CSW-NC composite cap beam as described above, and further comprising the following steps:

[0016] Use angle steel or T-shaped steel to make the inner support frame;

[0017] The top plate, bottom plate, flat steel plate, corrugated steel web and inner support frame are fixed together to form a steel frame, UHPC is poured to form a composite shell, and then steel bars are tied inside the composite shell;

[0018] Tensioning the first set of prestressed tendons; transporting the combined shell to the bridge site, and then hoisting it to the top of the pier;

[0019] pouring ordinary concrete into the inner cavity of the combined shell;

[0020] The main beam is hoisted on the cap beam, and then the second set of prestressed tendons are tensioned.

[0021] Preferably, before pouring UHPC to form the composite shell, the first shear studs or the second shear studs are embedded in each CSW plate.

[0022] Preferably, the steel bars are distributed at the bottom of the inner cavity of the combined shell.

[0023] Preferably, the process of pouring ordinary concrete in the inner cavity of the combined shell is: first pouring ordinary concrete in the middle of the combined shell, and then pouring it symmetrically from the middle of the combined shell to both ends of the combined shell.

[0024] Compared with the existing technology, the cap beam of the present invention is constructed without formwork, has little impact on the site, has good durability, long service life, high strength, high toughness, high bending bearing capacity, high performance-price ratio, light weight of the combined shell, simple steel frame production, and fast construction speed. The specific effects are:

[0025] 1. The composite shell fully utilizes the high compressive strength of UHPC and the lightweight, high shear yield strength of the corrugated steel web. Furthermore, the high strength and self-supporting properties of the corrugated steel web are fully utilized, serving not only as an external formwork but also as an integral part of the structure. This eliminates or significantly reduces formwork usage, significantly minimizing on-site workload and greatly facilitating construction. Furthermore, the inner cavity's ordinary concrete is poured using the UHPC + CSW composite shell as a formwork, significantly reducing on-site processes and land occupation, significantly minimizing adverse impacts on the social environment.

[0026] 2. The combined shell is arranged with a middle transverse diaphragm and an inner support frame, which has a simple structure and is easy to construct. The corrugated steel web of the combined shell greatly improves the shear strength of the cap beam. The inner support frame, on the one hand, improves the torsional rigidity of the structure and plays a role in fixing the prestressed tendons, preventing the combined shell from becoming unstable during the tensioning of the first layer of prestressed tendons and the pouring of concrete; on the other hand, it reduces the tensile stress and lateral deformation of the outer edge of the combined shell. The equally spaced inner support frames can effectively avoid local instability and damage. Secondly, they are simple to make and can effectively increase the construction speed. The setting of the middle transverse diaphragm strengthens the structural strength of the stress point of the cap beam. The frame formed by the corrugated steel web of the combined shell, the corrugated steel web of the middle transverse diaphragm and the inner support frame can further improve the torsional rigidity of the cap beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 It is a structural schematic diagram of the present invention;

[0029] Figure 2 It is a partial structural schematic diagram of the present invention;

[0030] Figure 3 for Figure 2 Schematic cross-sectional view along line AA;

[0031] Figure 4 for Figure 2 Schematic cross-sectional view along line BB;

[0032] Figure 5 Schematic diagram of the structure of the prestressed bundle of the present invention;

[0033] Figure 6 It is a perspective view of the present invention.

[0034] Reference numerals:

[0035] 1. Composite shell, 11. Top plate, 12. Bottom plate, 13. Flat steel plate, 111. Casting hole, 112. Ventilation hole, 2. Middle transverse diaphragm, 3. Internal support frame, 31. Transverse column, 32. Diagonal bracing column, 33. Longitudinal angle steel, 41. First corrugated steel web, 42. Second corrugated steel web, 5. First shear stud, 6. Prestressed tendon, 7. Ordinary concrete, 8. Pier, 9. Second shear stud. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0037] Refer to the attached Figure 2-4 The present embodiment provides a formwork-free ultra-large-scale UHPC-CSW-NC composite cap beam, comprising a UHPC prefabricated composite shell 1 with an inner cavity, wherein a plurality of middle transverse diaphragms 2 are distributed along the length direction of the composite shell 1, and an inner support frame 3 is fixed between the middle transverse diaphragm 2 and the composite shell 1, and between two adjacent middle transverse diaphragms 2. Corrugated steel webs are provided on both sides of the composite shell 1, at both ends of the composite shell 1, inside the top plate 11 of the composite shell 1, and on both sides of the middle transverse diaphragm 2. UHPC is cast between the two corrugated steel webs of the middle transverse diaphragm 2, i.e., the composite shell The shell is composed of UHPC and CSW. This structure can fully utilize the characteristics of corrugated steel webs and UHPC. Casting holes 111 and ventilation holes 112 are reserved on the top plate 11 of the combined shell 1. The internal support frame 3 includes transverse columns 31 and diagonal bracing columns 32. The two transverse columns 31 are arranged one above the other. The ends of the diagonal bracing columns 32 are fixed to the ends of the upper transverse columns 31. The two diagonal bracing columns 32 are arranged in a V-shape. The transverse columns 31 and the diagonal bracing columns 32 are both fixed to the combined shell 1. The inner cavity of the combined shell 1 is cast with ordinary concrete 7, and the middle transverse diaphragm 2 is set above the pier 8. The combined shell 1 is a stress point at the pier 8. The installation of the middle transverse diaphragm 2 helps to improve the strength of the structure at this location. Among them, UHPC is the abbreviation of Ultra-High Performance Concrete, CSW is the abbreviation of Corrugated Steel Web, and NC is the abbreviation of Normal Concrete 7.

[0038] The thickness of the UHPC of the top plate 11 is 6-10 cm, and the thickness of the UHPC of the bottom plate 12 is 12-15 cm; the compressive strength of the UHPC of the combined shell 1 is 120-150 MPa, and the tensile strength is 7-9 MPa.

[0039] The composite shell 1 utilizes corrugated steel webs (CSWs) on both sides of the composite shell 1. These CSWs are constructed as first corrugated steel webs 41, made from 12-20 mm thick steel plates. The concave-convex shape strengthens the connection between the composite shell 1 and the subsequently poured conventional concrete 7, providing self-stiffening properties, high shear strength, and no longitudinal load. No formwork is required to erect the first corrugated steel webs 41.

[0040] The top plate 11, both ends of the combined shell 1, and the UHPC of the middle transverse diaphragm 2 all use CSW as the template. The CSW of the top plate 11, both ends of the combined shell 1, and the middle transverse diaphragm 2 are set as the second corrugated steel web 42. The thickness of the second corrugated steel web 42 is 2 to 4 mm. It not only plays a structural role, but also acts as a template due to its self-stiffening function, so there is no need to set up other templates.

[0041] Refer to the attached Figure 1 The inner support frames 3 are symmetrically arranged along the central axis of the combined outer shell 1, and the spacing between the inner support frames 3 is 1.5-2m.

[0042] Refer to the attached Figure 4 The first corrugated steel webs 41 on both sides of the combined shell 1 are fixed between the top plate 11 and the bottom plate 12 in an embedded manner, and the diameters of the casting holes 111 and the air holes 112 are 150-200 mm and 45-55 mm respectively.

[0043] The transverse column 31 and the diagonal bracing column 32 are both angle steels or T-shaped steels. The two ends of the lower transverse column 31 are fixed to the first corrugated steel web 41 of the combined shell 1 through the longitudinal angle steel 33, and the upper transverse column 31 is fixed to the diagonal bracing column 32 and the first corrugated steel web 41 of the combined shell 1 through the longitudinal angle steel 33.

[0044] A plurality of first shear nails 5 are fixed to both the top plate 11 and the bottom plate 12 of the combined shell 1, so that the combined shell 1 and the ordinary concrete can be better connected into one.

[0045] The outer walls of the combined shell 1 are provided with flat steel plates 13. The side panels at both ends of the combined shell 1 are formed by casting UHPC between the flat steel plates 13 and the second corrugated steel web 42 as a formwork. Specifically, the thickness of the side panels at both ends of the combined shell 1 is 20-30 cm, the thickness of the central diaphragm 2 is 15-25 cm, the thickness of the top panel 11 is 6-8 cm, and the thickness of the bottom panel 12 is 10-15 cm.

[0046] Refer to the attached Figure 6 , the pouring hole 111 is located between the two vent holes 112 .

[0047] Refer to the attached Figure 5 Two groups of prestressed bundles 6 are arranged from top to bottom in the combined shell 1. The two ends of each group of prestressed bundles 6 are inclined downward. The upper and lower prestressed bundles 6 are respectively arranged at the upper and lower ends of the end of the combined shell 1.

[0048] The present invention also provides a construction method for a formwork-free ultra-large-scale UHPC-CSW-NC composite cap beam, comprising the above-mentioned formwork-free ultra-large-scale UHPC-CSW-NC composite cap beam, and further comprising the following steps:

[0049] Step 1: Use angle steel or T-shaped steel to make the inner support frame 3;

[0050] Step 2: Fix the top plate 11, bottom plate 12, flat steel plate 13, corrugated steel web and the prepared inner support frame 3 together to form a steel frame, cast UHPC to form the composite shell 1, and then tie steel bars inside the composite shell 1. Specifically, the steel bars are tied to the lower end of the inner cavity of the composite shell 1;

[0051] Step 3: Tensioning the first layer of prestressed tendons 6; transporting the combined shell 1 from the factory to the bridge site, and then hoisting it to the top of the pier 8;

[0052] Step 4: pour ordinary concrete 7 into the inner cavity of the combined shell 1 along the pouring hole 111 of the top plate 11; specifically, first pour ordinary concrete 7 in the middle of the combined shell 1, and then pour symmetrically from the middle of the combined shell 1 to the two ends of the combined shell 1 to avoid eccentric pouring.

[0053] Step 5: Hoist the main beam on the cap beam and tension the prestressed tendon 6 for the second time.

[0054] Among them, in step 4, before pouring UHPC to form the combined shell 1, the first shear nails 5 are embedded in the top plate 11 and the bottom plate 12, the second shear nails 9 are embedded in the first corrugated steel webs 41 on both sides of the combined shell 1, and the steel bars are tied to the first shear nails 5 on the bottom plate 12.

[0055] The cap beam of the present invention is constructed without formwork, has little impact on the site, has good durability, long service life, high strength, high toughness, high bending bearing capacity, and high performance-price ratio. Secondly, the combined shell 1 has a light weight, the steel frame is simple to manufacture, and the construction speed is fast. The specific effects are:

[0056] (1) The composite shell 1 fully utilizes the high compressive strength of UHPC and the light weight and high shear yield strength of the corrugated steel web. Furthermore, the high strength and self-supporting properties of the corrugated steel web are fully utilized, serving not only as an external formwork but also as a part of the structure. This eliminates or significantly reduces the use of formwork, significantly reducing the workload on the construction site and greatly facilitating construction. At the same time, ordinary concrete 7 is poured using the UHPC-CSW composite shell 1 as a formwork, significantly reducing on-site processes and land occupation, and significantly reducing adverse impacts on the social environment.

[0057] (2) The combined shell 1 is arranged with a middle transverse diaphragm 2 and an inner support frame 3, which has a simple structure and is easy to construct. The corrugated steel web of the combined shell 1 greatly improves the shear strength of the cap beam. The inner support frame 3, on the one hand, improves the torsional rigidity of the structure and plays a role in fixing the prestressed tendons, preventing the combined shell 1 made of UHPC-CSW from becoming unstable during the tensioning of the first layer of prestressed tendons 6 and the pouring of concrete. On the other hand, it reduces the tensile stress and lateral deformation of the outer edge of the combined shell 1. The inner support frame 3 with equal spacing can effectively avoid local instability and damage. Secondly, the inner support frame 3 is mainly made of 4 angle steels, which is simple to manufacture and can effectively increase the construction speed. The setting of the middle transverse diaphragm 2 strengthens the structural strength of the cap beam's stress point. The frame formed by the corrugated steel web of the combined shell 1, the corrugated steel web of the middle transverse diaphragm 2 and the inner support frame 3 can further improve the torsional rigidity of the cap beam.

[0058] Finally, it should be noted that the above 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 with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A formwork-free ultra-large-scale UHPC-CSW-NC composite cap beam, characterized in that: It includes a combined shell prefabricated with UHPC and having an inner cavity, wherein a plurality of middle transverse diaphragms are distributed in the combined shell along its length direction, and an inner support frame is fixed between the middle transverse diaphragm and the combined shell and between two adjacent middle transverse diaphragms, and corrugated steel webs are provided on both sides of the combined shell, both ends of the combined shell, the top plate of the combined shell, and both sides of the middle transverse diaphragm, UHPC is cast between the two corrugated steel webs of the middle transverse diaphragm, and casting holes and air vents are reserved on the top plate of the combined shell, the inner support frame includes a transverse column and an oblique support column, two of the transverse columns are arranged up and down, the ends of the oblique support column are fixed to the ends of the upper transverse columns, and the two oblique support columns are distributed in a V shape, the transverse columns and the oblique support columns are fixed to the combined shell, the inner cavity of the combined shell is cast with ordinary concrete, and the middle transverse diaphragm is arranged above the pier; CSW is used as webs on both sides of the combined shell.

2. The formwork-free ultra-large-scale UHPC-CSW-NC composite cap beam according to claim 1 is characterized in that: The thickness of the UHPC of the top plate is 6-10 cm, and the thickness of the UHPC of the bottom plate of the combined shell is 12-15 cm; the compressive strength of the UHPC of the combined shell is 120-150 MPa, and the tensile strength is 7-9 MPa.

3. The formwork-free ultra-large-scale UHPC-CSW-NC composite cap beam according to claim 1 is characterized in that: The CSWs on both sides of the combined housing are made of steel plates with a thickness of 12-20 mm.

4. The formwork-free ultra-large-scale UHPC-CSW-NC composite cap beam according to claim 1, characterized in that: The UHPC of the top plate, both ends of the combined shell, and the middle transverse partition all use CSW as a template, and the thickness of the CSW of the top plate, both ends of the combined shell, and the middle transverse partition is 2 to 4 mm.

5. The formwork-free ultra-large-scale UHPC-CSW-NC composite cap beam according to claim 1, characterized in that: The outer walls of both ends of the combined shell are provided with flat steel plates.

6. The formwork-free ultra-large-scale UHPC-CSW-NC composite cap beam according to claim 1, characterized in that: The two ends of the lower transverse column are fixed to the combined shell through longitudinal angle steels, and the upper transverse column is fixed to the diagonal bracing column and the combined shell through longitudinal angle steels.

7. The formwork-free ultra-large-scale UHPC-CSW-NC composite cap beam according to claim 1, characterized in that: A plurality of first shear nails are evenly arranged on the top plate and the bottom plate of the combined shell.

8. The formwork-free ultra-large-scale UHPC-CSW-NC composite cap beam according to claim 1, characterized in that: Two or three groups of prestressed bundles are arranged inside the combined shell.

9. A construction method for a formwork-free ultra-large-scale UHPC-CSW-NC composite cap beam, characterized in that: The method comprises the formwork-free ultra-large-scale UHPC-CSW-NC composite cap beam according to any one of claims 1 to 8, further comprising the following steps: Use angle steel or T-shaped steel to make the inner support frame; The top plate, bottom plate, flat steel plate, corrugated steel web and inner support frame are fixed together to form a steel frame, UHPC is poured to form a composite shell, and then steel bars are tied inside the composite shell; Tensioning the first set of prestressed tendons; transporting the combined shell to the bridge site, and then hoisting it to the top of the pier; pouring ordinary concrete into the inner cavity of the combined shell; The main beam is hoisted on the cap beam, and then the second set of prestressed tendons are tensioned.

10. The construction method of the formwork-free ultra-large-scale UHPC-CSW-NC composite cap beam according to claim 9, characterized in that: The process of pouring ordinary concrete in the inner cavity of the combined shell is as follows: first pouring ordinary concrete in the middle of the combined shell, and then pouring it symmetrically from the middle of the combined shell to both ends of the combined shell.

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