CN-121976458-A - Box girder stretching steel plate-UHPC (ultra high performance concrete) bleed-resistant strong structure and construction and design method

Abstract

The invention discloses a box girder stretching steel plate-UHPC anti-bleed strong structure and a construction and design method, and belongs to the technical field of bridge engineering reinforcement. The invention aims at the problem that the existing concrete box girder is easy to be debonded and aged after being bonded with steel, and combines the prestress tension steel plate and UHPC to perform active reinforcement and secondary reinforcement. The structure comprises a concrete box girder web plate, an oblique steel plate, an L-shaped steel layering, a connecting plate, a tensioning anchor plate, a tensioning piece, structural adhesive and a UHPC layer. The construction method comprises the steps of heating a steel plate to expand the steel plate, anchoring the steel plate, applying prestress by utilizing cooling shrinkage, pouring structural adhesive and pouring a UHPC layer. The design method provides a calculation formula for controlling stress, effective prestress and shearing bearing capacity of the tension. The invention realizes the active prestress of the steel plate, overcomes the ageing defect of the steel adhesive, improves the durability and the crack resistance of the structure and reduces the cost of the whole life cycle.

Inventors

• ZHANG YANG
• LIU YINGFENG
• HUANG SONGLING
• TANG HAO
• CHEN YI
• JIANG YIZHENG

Assignees

• 湖南大学

Dates

Publication Date

20260505

Application Date

20260408

Claims (10)

1. 1. The utility model provides a case roof beam stretch-draw steel sheet-UHPC anti bleed strong structure which characterized in that includes: a concrete box girder web (1); the oblique pasting steel plate (5) is obliquely pasted on the surface of the concrete box girder web (1); the L-shaped steel batten (2) is covered on the upper end of the inclined pasting steel plate (5) and is fixedly connected with the top plate of the concrete box girder web plate (1); The connecting plate (8) is fixed at the lower end of the oblique pasting steel plate (5); the tensioning anchor plate (7) is fixed at the lower part of the concrete box girder web plate (1) and positioned below the connecting plate (8); the tensioning piece (704) is arranged in the connecting plate (8) and the tensioning anchor plate (7) in a penetrating manner and is used for tensioning the oblique steel plate (5) so as to apply prestress; Structural adhesive (9) filled between the oblique steel plate (5) and the concrete box girder web (1), and And the UHPC layer (11) is covered on the outer sides of the concrete box girder web (1) and the oblique steel plate (5).
2. 2. The box girder tensioning steel plate-UHPC bleed strong structure according to claim 1, wherein the outer side surface of the oblique pasting steel plate (5) is provided with a shearing-resistant short stud (6), the surface of the concrete box girder web (1) is provided with a chiseling surface (10), and the UHPC layer (11) forms an integral stress structure with the oblique pasting steel plate (5) and the concrete box girder web (1) through the shearing-resistant short stud (6) and the chiseling surface (10).
3. 3. The box girder stretching steel plate-UHPC bleed-resistant strong structure according to claim 1, wherein the stretching piece (704) is one of finish-rolled twisted steel, high-strength steel wire bundles or steel strands, and the L-shaped steel batten (2) is provided with stiffening ribs (4) and is fixedly connected with the concrete box girder web (1) and the top plate through bolts (3).
4. 4. The construction method of the box girder tensioning steel plate-UHPC anti-bleed strong structure is used for applying prestress to the oblique pasting steel plate of the existing concrete box girder, and the oblique pasting steel plate (5) is obliquely pasted on the concrete box girder web plate (1) of the existing concrete box girder, and is characterized by comprising the following steps: A connecting plate (8) is fixed at the lower end of the oblique pasting steel plate (5), and a tensioning anchor plate (7) is fixed at the lower part of the concrete box girder web plate (1); Heating the oblique steel plate (5) to expand and stretch the oblique steel plate; penetrating and anchoring a tensioning piece (704) in the connecting plate (8) and the tensioning anchor plate (7); Stopping heating, naturally cooling and shrinking the oblique steel plate (5), and applying prestress to the oblique steel plate (5) through the tension piece (704).
5. 5. The construction method according to claim 4, wherein the pre-stressing the bias steel plate (5) further comprises applying an initial pre-stressing force by tightening a nut of the tension member (704) with a predetermined torque by a torque wrench in a heated state, and the naturally cooling shrinkage process applies a secondary pre-stressing force to the bias steel plate (5).
6. 6. Construction method according to claim 4 or 5, characterized in that it further comprises, after the prestressing, the steps of pouring a structural glue (9) between the oblique steel plate (5) and the concrete girder web (1) and pouring a UHPC layer (11) outside the concrete girder web (1) and the oblique steel plate (5).
7. 7. A method for designing a box girder tension steel sheet-UHPC bleed-resistant strong structure according to any one of claims 1 to 3, characterized by comprising the steps of: S1, determining tension control stress of the obliquely attached steel plate (5) The calculation formula is as follows: ; Wherein, the The axial force applied to the oblique steel plate (5) when the nut is screwed for the tension piece (704) is expressed by the formula It is determined that the number of the cells, To apply torque to the tension member (704), As a result of the torque coefficient, Is the nominal diameter of the tension member (704); Is the temperature difference before and after heating; 、 、 、 the nominal cross-sectional area, the elastic modulus, the thermal expansion coefficient and the strength design value of the oblique-attached steel plate (5) are respectively; s2, calculating effective prestress of the oblique-attached steel plate (5) The calculation formula is as follows: ; Wherein, the In order to account for the loss of prestress caused by deformation of the anchoring system, Prestress loss caused by steel relaxation; S3, calculating the shearing bearing capacity provided by the oblique-attached steel plate (5) The calculation formula is as follows: ; Wherein, the Is an included angle between the oblique pasting steel plate (5) and the beam axis, To account for the effects of secondary stress and hysteresis.
8. 8. The method of claim 7, wherein the stress hysteresis Calculated by the following formula: ; Wherein, the And Respectively the shearing force standard values on the sections of the experimental calculation before and after the reinforcement, The yield strain is 0.0015-0.0025.
9. 9. The method of claim 7, further comprising the step of calculating the total shear load capacity of the structure by the formula: ; Wherein, the As a factor of importance of the structure, Is the design value of the shearing force effect; And The shearing bearing capacity provided for the original box girder concrete and the original box girder stirrup respectively, Shear load capacity provided for the UHPC layer (11).
10. 10. A method according to claim 9, characterized in that the UHPC layer (11) provides a shear-carrying capacity Calculated by the following formula: ; Wherein, the For the shear strength utilization coefficient of UHPC, For the frontal cross-sectional area of the UHPC layer (11) in the web, And The axial pull initiation strength and the ultimate strength of UHPC, respectively.

Description

Box girder stretching steel plate-UHPC (ultra high performance concrete) bleed-resistant strong structure and construction and design method Technical Field The invention relates to the technical field of bridge engineering structure reinforcement, in particular to a box girder tensioning steel plate-UHPC bleed strong-resistant structure and a construction and design method. Background The 10-50 m span concrete box girder bridge has a simple structure, definite stress, and can be prefabricated in a standardized factory, and the bridge occupies a considerable proportion in the in-service bridge. However, the load standard of early construction is low, a large number of early concrete box girders are in long-term service, the problems of structural aging, performance degradation and the like are faced, and the rapidly-growing traffic flow and heavy overload bring higher requirements to the safety and reliability of the bridge structure. The box girder web cracking is the most common disease, and a large number of concrete box girder bridges are reinforced by adhering steel plates after the web cracking occurs, so that the stress of the box girder web is improved, and the structural safety is ensured. The traditional bonding steel reinforcement scheme has the following defects that firstly, under the coupling actions of overload, fatigue, ultraviolet rays, dry, wet, cold and hot circulation and the like, organic structural adhesive is degraded, peeled off and separated, so that a reinforced steel plate cannot be stressed together with a main structure, a web crack which is cracked before reinforcement is not effectively closed and is difficult to prevent external water vapor and chlorine salt from corroding an internal steel bar, a third and an external steel plate are required to be regularly coated with an anti-corrosion coating, the maintenance cost is high, fourth and the reinforced steel plates are exposed, the strength is obviously degraded under the extremely high temperature condition such as fire disaster and the like, the fireproof performance is insufficient, fifth and the crack damage of a box girder before reinforcement is generated, the reinforced steel plate cannot share the constant load, the structural rigidity is not obviously improved, and the sixth and the bonding steel reinforcement outer facade is visually outstanding, so that social panic is possibly caused, and the urban aesthetic requirements are not met. Ultra-high performance concrete (UHPC) is an advanced cement-based composite material prepared by optimizing grain composition, doping steel fibers and active powder, and has ultra-strong mechanical properties, durability and corrosion resistance. The prestress reinforcement can seal cracks and adjust the stress state of the structure. The invention combines the prestress tension steel plate and UHPC to actively reinforce, based on the existing situation of reinforcing the concrete bridge by bonding steel, fully utilizes the steel plate used in the first bonding steel reinforcement as a shearing-resistant main rib, applies prestress by a torsion wrench through a newly added L-shaped steel layering, an anchoring screw rod and an anchoring connecting piece, combines steel plate studs and web concrete embedded ribs as a shearing connecting piece, and post-casts UHPC as a structural stress and protective layer, thereby remarkably improving the crack resistance and the ultimate bearing capacity of the box girder, realizing the maintenance-free operation of the structure and reducing the cost of the whole life cycle of the bridge. Disclosure of Invention The invention aims to solve the technical problems that the debonding of a steel plate of a bonded steel reinforced concrete box girder can not prevent web cracking, and provides a steel plate debonding treatment and reinforcing anchoring technology based on the existing steel plate bonding reinforced box girder web, a prestress application structure for bonding the steel plate and a UHPC reinforcement repairing method are designed, and a corresponding prestress and reinforced girder shear bearing design method is provided. In order to solve the technical problems, the technical scheme adopted by the invention is as follows: The invention provides a box girder tensioning steel plate-UHPC (ultra high strength concrete) anti-bleed strong structure which comprises a concrete box girder web plate, an obliquely attached steel plate obliquely attached to the surface of the concrete box girder web plate, an L-shaped steel layering, a connecting plate, a tensioning anchor plate, a tensioning piece, structural adhesive and a UHPC layer. Specifically, the L-shaped steel batten is pressed and covered at the upper end of the inclined pasting steel plate and is fixedly connected with the top plate of the concrete box girder web plate, the structure can effectively strengthen the anchoring of the inclined pasting steel plate at the top, prevent the warpi