Layered prefabricated mouth-shaped section UHPC thin-walled bent cap and construction method

Abstract

The application discloses a layered prefabricated Houzixing cross-section UHPC thin-wall bent cap and a construction method thereof, which comprises a base and a top cover connected by steel bars; the cross-section of the base is a U-shaped structure with flanges, comprising a web, an upper flange, a bottom plate and an end plate; each web is perpendicular to the horizontal plane, and the length direction is parallel to the horizontal plane; the length direction of the corresponding bent cap is a variable-thickness structure and a variable-height structure; the base is provided with multiple webs, more than two axial skeleton steel bars and base prestressed steel bars; the top cover is provided with multiple transverse steel bars, multiple axial steel bars and top cover prestressed steel bars. During construction, the formwork is installed first, and the webs and the base prestressed steel bars are bound; after the base pouring is completed, steam curing is carried out; then, the top cover is poured; after the top cover pouring is completed, film covering and natural curing are carried out; finally, the base prestressed steel bars and the top cover prestressed steel bars are tensioned. The application can reduce the dosage of ultra-high performance concrete, reduce the influence on the road during transportation and reduce the outer diameter of the prestressed steel bars.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bent cap construction, in particular to a layered prefabricated H-shaped cross-section UHPC thin-walled bent cap and a construction method. BACKGROUND

[0002] The existing prefabricated thin-walled bent cap technology realizes the goal of reducing the self-weight of the bent cap by using ultra-high performance concrete, i.e., UHPC.

[0003] However, for some specific occasions, such as the prefabricated beam type of small box girder or T girder adopted by the main girder, and the conventional urban bridge form with a bridge width of 25-32 m, the following disadvantages still exist:

[0004] 1) The UHPC bent cap with a closed cross-section has a large amount of UHPC and steel strand, and the inner mold is prone to floating during construction, and the inner mold cannot be taken out for reuse.

[0005] 2) The UHPC bent cap with a π-shaped cross-section has a small amount of UHPC and steel strand, and the construction is relatively simple. However, the structure has relatively weak torsional resistance, and is only suitable for design cases where the torsion is not controlled.

[0006] Therefore, how to reduce the amount of ultra-high performance concrete, reduce the construction risk, and improve the working performance of the structure has become a technical problem urgently to be solved by the technical personnel in the field. SUMMARY

[0007] In view of the above-mentioned defects of the prior art, the present application provides a layered prefabricated H-shaped cross-section UHPC thin-walled bent cap and a construction method, which realizes the purpose of reducing the amount of ultra-high performance concrete, reducing the size of the thin-walled bent cap, ensuring the flowability of UHPC pouring, and improving the crack resistance and shear bearing capacity of the bent cap.

[0008] To achieve the above-mentioned purpose, the present application discloses a layered prefabricated H-shaped cross-section UHPC thin-walled bent cap, comprising a base and a top cover; the cross-section of the top cover is rectangular; the base and the top cover are connected by steel bars.

[0009] Among them, the cross-section of the base is a U-shaped structure with flanges, including webs on both sides, upper flanges extending outward on the upper end of each web, a bottom plate connecting the bottom ends of the two side webs, and end plates at both ends of the two side webs;

[0010] Each web is perpendicular to the horizontal plane, and the length direction is parallel to the horizontal plane. The corresponding bent cap length direction is a variable thickness structure and a variable height structure, i.e., the thickness and height near the middle part are greater than those near the two ends;

[0011] Each upper flange extends outward by a distance equal to the outer edge of the corresponding part of the top cover;

[0012] Each of the end plates and the corresponding web plates, and the position of the bottom plate are provided with a support;

[0013] The base is provided with multiple web reinforcement, two or more axial skeleton reinforcement and base prestressed reinforcement;

[0014] The top cover is provided with multiple transverse reinforcement, multiple axial reinforcement and top cover prestressed reinforcement;

[0015] Each of the web reinforcement includes a U-shaped main body part matched with the cross section of the base, and two end bending parts extending to the outside of the corresponding upper flange after extending to the outside of the web plate on both sides of the top cover;

[0016] Each of the axial skeleton reinforcement is arranged at the position close to the upper end of the corresponding web plate, and the corner part of the corresponding web plate and the bottom plate;

[0017] Each of the transverse reinforcement is arranged parallel to the bottom plate, and is overlapped or welded with each of the corresponding axial reinforcement;

[0018] Each of the axial reinforcement is parallel to the axial direction of the bent cap;

[0019] Each of the base prestressed reinforcement is arranged in the web plate on both sides, and is arranged in a curved form according to the stress requirement;

[0020] Each of the top cover prestressed reinforcement is arranged inside the top cover along the axial direction of the bent cap, and is in a straight form, and the vertical position is in the center of the top cover.

[0021] Preferably, the outer side surface of the bottom plate at both ends is flush with the corresponding web plate, and the variable cross section structure is used according to the bearing condition.

[0022] Preferably, the slope ratio of each of the supports is 1:3.

[0023] Preferably, the position corresponding to each of the support columns connected to the bottom plate in the inner cavity of the base is provided with two supporting partitions corresponding to the shape of the support column;

[0024] The multiple supporting partitions and the web plates on both sides form a tubular structure matched with the cross section of the support column above the support.

[0025] More preferably, the chamfer is arranged between each of the supporting partitions and the corresponding web plate, and between the bottom plate.

[0026] More preferably, the corresponding support column connecting part of each of the web plate and each of the supporting partition is provided with multiple embedded connecting parts.

[0027] Preferably, each of the bottom prestressed steel bars and each of the top prestressed steel bars is in unbonded form.

[0028] The application also provides a construction method of the layered prefabricated U-shaped cover beam, characterized in that the method comprises the following steps:

[0029] Step 1: installing a formwork and a support system, and binding all the web bars and all the bottom prestressed steel bars;

[0030] Step 2: pouring the bottom part with ultra-high performance concrete (UHPC) so that the two end bending parts of each web bar are exposed from the upper end surfaces of the two side webs;

[0031] Step 3: after the bottom part reaches the design requirements, removing the formwork, building a shed frame, and performing steam curing;

[0032] Step 4: installing all the transverse steel bars of the top cover and fixing them by spot welding or binding;

[0033] Step 5: installing all the axial steel bars and the top prestressed steel bars of the top cover;

[0034] Step 6: pouring the top cover with high-strength concrete, covering a film after pouring is completed, and naturally curing for 7 days;

[0035] Step 7: tensioning the bottom prestressed steel bars and the top prestressed steel bars.

[0036] Preferably, in the step 1, the positions of the support columns arranged for the bottom part are provided with corresponding pre-buried connecting pieces.

[0037] Preferably, in the step 3, the steam curing time is 5 days, and the temperature is not lower than 80℃.

[0038] The application has the following beneficial effects:

[0039] The application of the application reduces the amount of ultra-high performance concrete used by the cover beam, reduces the influence on the road during transportation, reduces the outer diameter of the prestressed steel bars, is beneficial to reducing the size of the thin-walled cover beam, ensures the flowability of UHPC pouring, improves the crack resistance and shear bearing capacity of the cover beam, improves the crack resistance and bending bearing capacity of the cover beam in a curved state, improves the structural deformation capacity, greatly reduces the number of internal structures of the component, reduces the interference with UHPC pouring, and ensures the pouring quality.

[0040] The concept, specific structure and technical effects of the application will be further described below with reference to the accompanying drawings, so as to fully understand the purposes, features and effects of the application. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 A sectional view showing an embodiment of the present application.

[0042] Figure 2 A sectional view showing an embodiment of the present application. Figure 1 A top plan view showing an embodiment of the present application.

[0043] Figure 3 A sectional view showing an embodiment of the present application. Figure 1 A sectional view showing an embodiment of the present application.

[0044] Figure 4 A sectional view showing an embodiment of the present application.

[0045] Figure 5 A sectional view showing an embodiment of the present application. Figure 4 A sectional view showing an embodiment of the present application.

[0046] Figure 6 A sectional view showing an embodiment of the present application.

[0047] Figure 7 A sectional view showing an embodiment of the present application.

[0048] Figure 8 A sectional view showing an embodiment of the present application.

[0049] Figure 9 A sectional view showing an embodiment of the present application.

[0050] Figure 10 A sectional view showing an embodiment of the present application.

[0051] Figure 11 A sectional view showing an embodiment of the present application. DETAILED DESCRIPTION

[0052] EMBODIMENT

[0053] As shown in the drawings, the layered prefabricated Houzixing cross-section UHPC thin-walled cap beam comprises a base 1 and a top cover 2; the cross-section of the top cover 2 is rectangular; the base 1 and the top cover 2 are connected by steel bars; Figures 1 to 6 The cross-section of the base 1 is a U-shaped structure with flanges, comprising a web plate 3 on both sides, an upper flange 4 extending outward on the upper end of each web plate 3, a bottom plate 5 connecting the bottom ends of the two side web plates 3, and an end plate 6 at the ends of the two side web plates 3;

[0054] Each web plate 3 is perpendicular to the horizontal plane, and the length direction is parallel to the horizontal plane. The corresponding cap beam length direction is a variable thickness structure and a variable height structure, that is, the thickness and height near the middle part are greater than those near the two ends;

[0055] ​

[0056] Each upper flange 4 extends outwardly to a distance flush with the outer edge of the corresponding portion of the top cover 2;

[0057] Each end plate 6 and the corresponding web 3 are provided with a support at the position connected with the bottom plate 5;

[0058] The base 1 is provided with a plurality of webs 7, two or more axial skeleton steel bars 8 and base prestressed steel bars 9;

[0059] The top cover 2 is provided with a plurality of transverse steel bars 10, a plurality of axial steel bars 11 and top cover prestressed steel bars 12;

[0060] Each web 7 comprises a U-shaped main body part matched with the cross section of the base 1, and end bending parts at both ends of the main body part, which extend into the top cover 2 and then extend to the outside of the corresponding upper flange 4 and then bend inwardly;

[0061] Each axial skeleton steel bar 8 is arranged at a position close to the upper end of the corresponding web 3 and at the corner part of the corresponding web 3 connected with the bottom plate 5;

[0062] Each transverse steel bar 10 is arranged parallel to the bottom plate 5 and is overlapped or welded with the corresponding axial steel bar 11;

[0063] Each axial steel bar 11 is parallel to the axial direction of the cap beam;

[0064] Each base prestressed steel bar 9 is arranged in the two side webs 3 and is arranged in a curved form according to the stress requirement;

[0065] Each top cover prestressed steel bar 12 is arranged inside the top cover 2 along the axial direction of the cap beam and is in a straight form and is vertically arranged at the center of the top cover 2.

[0066] The application of the present application makes the cap beam adopt a layered H-shaped section form, reduces the amount of ultra-high performance concrete, and the overall cap beam can be reduced by more than 40% compared with the solid cap beam. The influence on the road during transportation is reduced, the hoisting weight is reduced, and the construction measure cost is saved.

[0067] The application of the present application can improve the crack resistance and shear bearing capacity of the cap beam by arranging webs in the base of the cap beam.

[0068] The application of the present application can improve the crack resistance and bending bearing capacity of the cap beam in the bending state by arranging axial steel bars in the top cover of the cap beam, and improve the structural deformation capacity.

[0069] The application of the present application only arranges webs, transverse steel bars and a small amount of axial steel bars inside the cap beam, which greatly reduces the number of internal structures of the component, reduces the interference with the pouring of UHPC, and ensures the pouring quality.

[0070] In some embodiments, the bottom plate 5 is flush with the outer side of the corresponding two side webs 3 at both ends, and the variable cross-section structure is used according to the bearing condition.

[0071] In some embodiments, the slope ratio of each supporting column is 1:3.

[0072] In some embodiments, two supporting partitions 13 are arranged in the inner cavity of the base 1 corresponding to the position of each supporting column connected with the bottom plate 5, and the shape of the supporting partitions 13 corresponds to the shape of the supporting column.

[0073] The plurality of supporting partitions 13 and the two side webs 3 form a tubular structure above the supporting column, which matches the cross-section of the supporting column.

[0074] In some embodiments, a chamfer is arranged between each supporting partition 13 and the corresponding web 3, and between the supporting partition 13 and the bottom plate 5.

[0075] In some embodiments, a plurality of embedded connecting pieces 14 are arranged in the connecting part of each web 3 and each supporting partition 13 with the corresponding supporting column.

[0076] In some embodiments, each base prestressed reinforcement 9 and each top cover prestressed reinforcement 12 is in unbonded form.

[0077] The application of the prestressed reinforcement of the cap beam is in unbonded form, which can reduce the outer diameter of the prestressed reinforcement, facilitate the reduction of the size of the thin-walled cap beam, and ensure the flowability of the UHPC pouring.

[0078] As shown in Figures 7 to 11 The application also provides a construction method of the layered prefabricated UHPC thin-walled cap beam with a hollow square cross-section, which comprises the following steps:

[0079] Step 1, installing the formwork 15 and the support system 16, and binding all the web reinforcements 7 and all the base prestressed reinforcements 9;

[0080] Step 2, pouring the base 1 with the ultra-high performance concrete (UHPC), and making the two end bending parts of each web reinforcement 7 exposed from the upper end surface of the two side webs 3;

[0081] Step 3, after the base 1 meets the design requirements, removing the formwork 15, building a shed frame, and performing steam curing;

[0082] Step 4, installing all the transverse reinforcements 10 of the top cover 2, and fixing them by spot welding or binding;

[0083] Step 5, installing all the axial reinforcements 11 and the top cover prestressed reinforcement 12 of the top cover 2;

[0084] Step 6, pouring the top cover 2 with the ultra-high performance concrete (UHPC), covering a film after pouring, and naturally curing for 7 days;

[0085] Step 7, tensioning the bottom base prestressed steel bars 9 and the top cover prestressed steel bars 12.

[0086] In some embodiments, in step 1, the positions of the supporting columns set for the base 1 are each provided with a corresponding pre-buried connecting piece 14.

[0087] In some embodiments, in step 3, the steam curing time length is 5 days, and the temperature is not less than 80℃.

[0088] The preferred embodiments of the present application are described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations without departing from the concept of the present application. Therefore, any technical solutions obtained by logical analysis, reasoning or limited experiments based on the prior art according to the concept of the present application should be within the protection scope defined by the claims.

Claims

1. A layered prefabricated H-shaped section UHPC thin-walled cap beam, comprising a base (1) and a top cover (2) ; the section of the top cover (2) is rectangular; the base (1) and the top cover (2) are connected by steel bars; the section of the base (1) is a U-shaped structure with flanges, comprising webs (3) on both sides, upper flanges (4) extending outward on the upper end of each web (3), a bottom plate (5) connecting the bottom ends of the webs (3) on both sides, and end plates (6) at both ends of the webs (3) on both sides; characterized in that: a plurality of web bars (7), two or more axial skeleton steel bars (8) and base prestressed steel bars (9) are arranged in the base (1) ; a plurality of transverse steel bars (10), a plurality of axial steel bars (11) and top cover prestressed steel bars (12) are arranged in the top cover (2) ; each web bar (7) comprises a U-shaped main body part matched with the cross section of the base (1), and end bending parts at both ends extending upward into the top cover (2) and then extending outward to the corresponding upper flanges (4) and then bending inward; each axial skeleton steel bar (8) is arranged at the position close to the upper end of the corresponding web (3) and the corner part where the corresponding web (3) is connected with the bottom plate (5) ; each transverse steel bar (10) is arranged parallel to the bottom plate (5) and is overlapped or welded with each corresponding axial steel bar (11) ; each axial steel bar (11) is parallel to the axial direction of the cap beam; each base prestressed steel bar (9) is arranged in the web (3) on both sides and is arranged in a curved form according to the stress requirement; each top cover prestressed steel bar (12) is arranged inside the top cover (2) along the axial direction of the cap beam and is in a straight form, and the vertical position is at the center of the top cover (2) ; the outer sides of the bottom plate (5) at both ends are flush with the outer sides of the corresponding webs (3) on both sides, and the variable cross section structure is adopted according to the bearing capacity; two support partitions (13) are arranged in the inner cavity of the base (1) corresponding to the position of each support column connected with the bottom plate (5), and the shape of the support partitions (13) corresponds to the shape of the support column; the support partitions (13) and the webs (3) on both sides form a tubular structure matched with the cross section of the support column above the support column; a plurality of embedded connecting pieces (14) are arranged in the connecting part of each web (3) and each support partition (13) with the corresponding support column; each web (3) is perpendicular to the horizontal plane, and the length direction is parallel to the horizontal plane, and the length direction is a variable thickness structure and a variable height structure, that is, the thickness and height close to the middle part are greater than the thickness and height close to the both ends; the distance of each upper flange (4) extending outward is flush with the outer edge of the corresponding part of the top cover (2) ; each end plate (6) and the corresponding web (3) and the bottom plate (5) are provided with a support at the connecting position; the slope ratio of each support is 1:3; each base prestressed steel bar (9) and each top cover prestressed steel bar (12) is in a non-bonding form; comprising the following steps: ​ ​ ​ ​ ​ ​ ​ ​ 2. The layered precast hollow U-shaped UHPC beam according to claim 1, characterized in that, ​ 3. The layered precast hollow U-shaped UHPC beam according to claim 1, characterized in that, ​ ​ 4. The layered precast hollow U-shaped UHPC beam according to claim 3, characterized in that, ​ 5. The layered precast hollow U-shaped UHPC cover beam according to claim 1, characterized in that, ​ ​ ​ 6. The layered precast hollow U-shaped UHPC beam according to claim 5, characterized in that, ​ 7. The layered precast hollow U-shaped UHPC cover beam according to claim 1, characterized in that, ​ 8.The construction method of layered prefabricated hollow UHPC roof beam with herringbone section according to claim 1, wherein, ​ Step 1, install the formwork (15) and the support system (16), bind all the web bars (7) and all the base prestressed steel bars (9); Step 2, pour the base (1) with ultra-high performance concrete, i.e. UHPC, and make the two end bending parts of each web bar (7) exposed from the upper end surface of the web plate (3) on both sides; Step 3, after the base (1) reaches the design requirements, remove the formwork (15), build a shed frame, and perform steam curing; Step 4, install all the transverse steel bars (10) of the top cover (2) and fix them by spot welding or binding; Step 5, install all the axial steel bars (11) and the top cover prestressed steel bars (12) of the top cover (2); Step 6, pour the top cover (2) with ultra-high performance concrete, i.e. UHPC, and cover a film after pouring, and naturally cure for 7 days; Step 7, tension the base prestressed steel bars (9) and the top cover prestressed steel bars (12).

9. The construction method of layered precast hollow UHPC roof beam with herringbone section according to claim 8, characterized in that, In the step 1, the positions of the support columns arranged for the base (1) are all provided with corresponding pre-buried connecting pieces (14).

10. The construction method of layered precast hollow UHPC roof beam with herringbone section according to claim 8, characterized in that, In the step 3, the length of time of the steam curing is 5 days, and the temperature is not lower than 80℃.

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