CN216405074U

CN216405074U - ECC and reinforced concrete composite pier structure

Info

Publication number: CN216405074U
Application number: CN202122966646.3U
Authority: CN
Inventors: 杨光煜; 谢亮; 李春磊; 刘绍卿; 于沉香; 尤涵锐; 吴琪
Original assignee: Wuhan Surveying Geotechnical Research Institute Co Ltd of MCC
Current assignee: Wuhan Surveying Geotechnical Research Institute Co Ltd of MCC
Priority date: 2021-11-26
Filing date: 2021-11-26
Publication date: 2022-04-29
Anticipated expiration: 2031-11-26

Abstract

The utility model provides an ECC and reinforced concrete composite pier structure. The pier structure comprises a pier body and a bearing platform, wherein the pier body comprises a reinforced concrete section at the upper part and an ECC material reinforcing section connected with the bearing platform at the lower part, a reinforcement cage of the ECC material reinforcing section and a reinforcement cage of the reinforced concrete section are of an integral structure, and part or all longitudinal bars of the pier body are replaced by CFRP bars; a buckling constraint structure is arranged in the ECC material reinforcing section, a CFRP sheet is coated on the outer surface of the ECC material reinforcing section, and the buckling constraint structure comprises a steel sleeve and a steel plate welded at one port of the steel sleeve; CFRP sheet reinforcing belts are arranged on the outer surface of the reinforced concrete section at intervals. The utility model fully exerts the advantages of high ductility, high toughness, good durability and the like of ECC and CFRP materials, can inhibit the pier longitudinal bars from local buckling damage, improves the bearing capacity and ductility of the pier structure, and further greatly improves the seismic performance of the pier structure.

Description

ECC and reinforced concrete composite pier structure

Technical Field

The utility model relates to the field of bridge engineering, in particular to a pier structure compounded by ECC (Engineered Cementitious Composite) and Reinforced concrete, which is Reinforced by CFRP (carbon Fiber Reinforced plastics).

Background

The bridge serves as infrastructure in social development, bears normal operation of a traffic system and development of highway and railway transportation industry, and plays an important role in national economic development and regional communication. However, most bridges in China are in very severe environments, corrosion of external corrosive media is difficult to avoid, reinforcing steel bars are corroded by the corrosive media continuously to be corroded, the diameter of the reinforcing steel bars is reduced, the strength of the reinforcing steel bars is reduced, and accordingly the bearing capacity and the anti-seismic performance of the bridge structure are reduced. And China is located in earthquake frequent zones, earthquakes have the characteristics of high intensity, high frequency, shallow earthquake sources and wide distribution, and the bridge with degraded earthquake resistance in the service life is more seriously damaged under the action of the earthquakes. A large number of post-earthquake investigations show that the plastic hinge area of the pier is easy to be damaged by earthquake in the reinforced concrete bridge structure, so that the whole bridge is collapsed, the traffic and transportation line is interrupted, and the disaster relief work after the earthquake is delayed seriously. In the conventional anti-seismic design of the existing bridge, the ductile deformability of the bridge pier structure is increased by increasing the section size of the bridge pier and arranging steel bars in a plastic hinge area in an encrypted manner, but the efficiency-improving behavior of the traditional method on the bridge structure level is limited in the improvement degree of the anti-seismic performance, and the construction difficulty and the construction cost can be greatly increased. Therefore, it is necessary to replace the reinforced concrete material of the pier with a high-performance material, so as to improve the seismic performance of the pier.

ECC is a fiber reinforced cement-based composite material designed based on the principles of micromechanics and fracture mechanics. Under the condition that the volume mixing amount of the fiber is about 2 percent, the ultimate tensile strain energy of the fiber reaches more than 3 percent, the fiber has obvious strain-hardening and multi-crack cracking characteristics, and the width of a multi-crack cracking crack in a saturated state is more than 0.1 mm. Therefore, the ECC material can dissipate seismic energy through large deformation, multi-slit cracking and strain hardening, and has good seismic performance and powerful energy consumption capability. And ECC can inhibit the development of structural cracks and improve the durability of the structure, so the ECC is gradually popularized and applied in the field of civil engineering.

The CFRP is a composite material formed by winding, molding or pultrusion of a carbon fiber reinforced material and a matrix material, and has the advantages of light weight, high strength, strong corrosion resistance, good elastic performance, high tensile strength and the like. The existing research shows that the CFRP bar does not need to consider the durability problem caused by the corrosion of the steel bar, so compared with the common steel bar, the CFRP bar is more suitable for serving as a reinforcing bar of a service structure in a corrosive environment (such as an acid rain area, a coastal area, a sea island and the like). The corrosion-resistant structure can solve the problem of corrosion of corrosive media, greatly improve the bearing capacity and the deformability of the structure and obviously improve the working performance of the structure in a normal use stage.

Disclosure of Invention

In order to solve the problems of corrosion of corrosive media of the pier and insufficient anti-seismic performance, the utility model provides the pier structure compounded by the ECC and the reinforced concrete, the composite pier structure can fully exert the advantages of high ductility, high toughness, good durability and the like of ECC and CFRP materials, can prevent the pier longitudinal bars 3 from being locally bent and damaged, improves the bearing capacity and ductility of the pier structure, and further greatly improves the anti-seismic performance of the structure.

In order to achieve the technical purpose, the utility model provides an ECC and reinforced concrete composite pier structure, which comprises a pier body and a bearing platform, wherein the pier body comprises a reinforced concrete section at the upper part and an ECC material reinforcing section connected with the bearing platform at the lower part, a reinforcement cage of the ECC material reinforcing section and a reinforcement cage of the reinforced concrete section are of an integral structure, and part or all longitudinal bars of the pier body are replaced by CFRP bars; a buckling constraint structure is arranged in the ECC material reinforcing section, a CFRP sheet is coated on the outer surface of the ECC material reinforcing section, and the buckling constraint structure comprises a steel sleeve and a steel plate welded at one port of the steel sleeve; CFRP sheet reinforcing belts are arranged on the outer surface of the reinforced concrete section at intervals.

The utility model has the following excellent technical scheme: a sealing rubber cushion layer is arranged on the inner wall of the steel sleeve, and the upper end of the sealing rubber cushion layer is 5-25 mm higher than the steel sleeve; and a circle of steel sleeve positioning holes are formed in the end, far away from the steel plate, of the steel sleeve, steel plate positioning holes are formed in the steel plate, and the steel sleeve and the steel plate are respectively bound to reinforcement cage stirrups or longitudinal reinforcements of the pier body and the bearing platform through the positioning holes.

The utility model has the following excellent technical scheme: the replacement rate of the CFRP rib is 25% -100%, and the replacement rate of the CFRP rib can be selected by 50% in consideration of the problems of material utilization rate, economy, construction and the like.

The utility model has the following excellent technical scheme: the CFRP sheet is a material layer which is coated on the outer surface of the ECC material reinforcing section in a pasting mode after epoxy resin glue is coated on the outer surface of the ECC material reinforcing section.

The utility model has the following excellent technical scheme: the CFRP sheet reinforcing strips are arranged in 5-20 rows and are distributed on the outer surface of the reinforced concrete section at equal intervals, the height of each CFRP sheet reinforcing strip is 300-500 mm, and the net distance between every two adjacent CFRP sheet reinforcing strips is 1000-3000 mm.

The utility model has the following excellent technical scheme: the inner diameter of the steel sleeve is larger than the outer diameter of the longitudinal reinforcement steel bar cage of the pier body, and the steel sleeve is sleeved outside the steel bar cage; the side length of the steel plate is not less than 70d, and d is the diameter of the longitudinal steel bar.

The utility model has the following excellent technical scheme: the inner diameters of the steel sleeve positioning hole and the steel plate positioning hole are 5-20 mm.

The height of the steel sleeve is twice the plastic hinge height of the pier bottom of the pier, the inner diameter of the steel sleeve is larger than the outer diameter of the longitudinal bar reinforcement cage, the steel sleeve has the function of providing lateral restraint for the reinforcement to prevent the longitudinal bar from being locally pressed and bent, and the thickness and the inner diameter can be determined according to actual conditions. The steel sleeve and the steel plate bind the buckling constraint structure on the stirrup or the longitudinal bar of the reinforcement cage through the positioning holes so as to avoid the separation of the buckling constraint structure and the reinforcement cage in the use process. The rubber cushion layer is used for avoiding mortar to flow into the gap between the steel sleeve and the steel reinforcement cage when concrete is poured, and the gap is reserved so as to meet the axial deformation of the longitudinal bar. In addition, rubber can also prevent that steel sleeve and concrete from atress jointly in the structure use to ensure that the steel sleeve can more effectively play a role.

The two-time plastic hinge area is valued according to the equivalent plastic hinge length specified in the highway bridge earthquake resistance design Specification (JTG/T2231-01-2020) in China, and then the height of the two-time plastic hinge area, namely the replacement height of the ECC material, can be obtained by taking the value of two times of the equivalent plastic hinge length.

According to the method, part or all of longitudinal steel bars of the pier are replaced by CFRP (carbon fiber reinforced plastics) bars, the longitudinal bars in the range of twice the plastic hinge of the bottom of the pier are laterally constrained by a buckling constraint structure, the concrete in the area of twice the plastic hinge of the bottom of the pier is replaced by ECC (error correction code) materials, CFRP sheets are wrapped on the surfaces of the ECC materials, strip-shaped CFRP sheets are used for strip reinforcement of the pier bodies at intervals, and the construction of the composite pier is completed. The composite pier structure combines the high-performance material ECC and the CFRP, fully exerts the advantages of high ductility and high energy consumption of the ECC material and the advantages of high strength, good corrosion resistance and the like of the CFRP material, can inhibit the pier bottom longitudinal ribs from being pressed and bent, and greatly improves the bearing capacity, the energy consumption capacity and the durability of the pier.

The utility model has the beneficial effects that:

1. the composite pier structure can fully utilize the characteristics of high ductility, high strength, good corrosion resistance and the like of ECC and CFRP materials, and greatly improves the crack resistance, the energy consumption capability and the durability of the pier structure.

2. Due to the fact that ECC and CFRP materials are expensive, the cost of replacing reinforced concrete materials of the bridge pier with high-performance materials is high, engineering cost can be greatly increased, and enterprise profit rate is reduced. The composite pier structure provided by the utility model has the advantages that the problems of material utilization rate, economy, construction and the like are considered, the replacement height of the ECC material is twice the plastic hinge height of the pier bottom, and the energy consumption capacity and the bearing capacity of the pier can be greatly improved on the premise of saving the engineering cost.

3. A large number of previous earthquake damage experiences show that longitudinal rib buckling, concrete crushing and peeling and other phenomena can occur in a plastic hinge area at the bottom of a reinforced concrete pier under the action of high axial pressure ratio and earthquake. The composite pier structure can form a hoop effect through the buckling constraint structure, can play a good lateral constraint role on the longitudinal reinforcing steel bars of the pier, can effectively prevent the longitudinal reinforcing steel bars from being damaged by local buckling, improves the bearing capacity and ductility of the pier structure, and further enhances the seismic resistance of the pier.

4. The CFRP (carbon fiber reinforced plastics) wrapped sheet material disclosed by the utility model not only can play a role of a hoop for an ECC (error correction code) material in a plastic hinge area, but also can inhibit the rigidity degradation of the ECC material. And the medium such as water in the external environment can be prevented from invading the bridge pier through the crack, so that the common steel bars in the bridge pier are protected from being corroded, and the durability of the structure is improved.

The composite pier structure does not change the pier structure form, has reasonable structural stress, can more effectively utilize materials, fully exerts the performance of high-performance materials, has simple construction process, small and portable construction machinery and shorter construction period, and has stronger popularization and application values for severe corrosive environments and earthquake-prone zones.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1;

FIG. 3 is a cross-sectional view taken along line B-B of FIG. 1;

FIG. 4 is a schematic illustration of a steel sleeve in the present invention;

FIG. 5 is a schematic view of a buckling restrained structure in the present invention.

In the figure: 1-ECC material reinforcing section, 2-reinforced concrete section, 3-longitudinal steel bar, 4-CFRP sheet, 5-steel sleeve, 5-1-steel sleeve positioning hole, 6-bearing platform, 7-steel plate, 7-1-steel plate positioning hole, 8-sealing rubber and 9-CFRP sheet reinforcing belt.

Detailed Description

The utility model is further illustrated by the following figures and examples. Fig. 1 to 5 are drawings of embodiments, which are drawn in a simplified manner and are only used for the purpose of clearly and concisely illustrating embodiments of the present invention. The following claims presented in the drawings are specific to embodiments of the utility model and are not intended to limit the scope of the claimed invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "inner", "outer", "left", "right", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, or the orientations or positional relationships that the products of the present invention are conventionally placed in use, or the orientations or positional relationships that are conventionally understood by those skilled in the art, and are used for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the equipment or elements referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.

The pier structure combining the ECC and the reinforced concrete provided in the embodiment comprises a pier body and a bearing platform 6, wherein the pier body comprises a reinforced concrete section 2 at the upper part and an ECC material reinforcing section 1 connected with the bearing platform 6 at the lower part, a reinforcement cage of the ECC material reinforcing section 1 and a reinforcement cage of the reinforced concrete section 2 are of an integral structure, the ECC material is adopted to replace concrete in a plastic hinge area twice the pier bottom of the pier to form the ECC material reinforcing section 1, an interface agent is coated on the contact surface of the ECC material 1 and the concrete, so that the bonding strength of the ECC material 1 and the concrete is enhanced, and 25% -100% of longitudinal bars 3 of the pier body are replaced by CFRP bars; the ECC material reinforcing section 1 is internally provided with a buckling constraint structure, the outer surface of the ECC material reinforcing section is coated with a CFRP sheet 4, the CFRP sheet 4 is a material layer which is formed by cleaning the surface of the cured and formed ECC material 1, then coating an epoxy resin adhesive on the surface of the cured and formed ECC material 1, and then adhering the CFRP sheet 4 to completely wrap the outer surface of the ECC material 1; CFRP sheet reinforcing belts 9 are arranged on the outer surface of the reinforced concrete section 2 at intervals, 5-20 strips of CFRP sheets 9 are arranged, the strip height of each strip of CFRP sheet 9 is 300-500 mm, and the net distance between every two adjacent strips of CFRP sheets 9 is 1000-3000 mm.

According to the pier structure compounded by the ECC and the reinforced concrete, as shown in fig. 4 and 5, the buckling constraint structure comprises a steel sleeve 5 and a steel plate 7 welded at one port of the steel sleeve 5, a sealing rubber cushion layer 8 is arranged on the inner wall of the steel sleeve 5, the inner diameter of the steel sleeve 5 is larger than the outer diameter of a longitudinal bar reinforcement cage of a pier body and is sleeved outside the reinforcement cage, the height of the steel sleeve 5 is twice the height of a plastic hinge at the bottom of the pier, and the thickness and the inner diameter can be determined according to actual conditions. The side length of the steel plate 7 is not less than 70d, d is the diameter of a longitudinal steel bar, the upper end of the sealing rubber cushion layer 8 is 5-25 mm higher than the steel sleeve 5, and the thickness of the sealing rubber cushion layer 8 can be determined according to specific conditions; the end opening of the steel sleeve 5, which is far away from the steel plate 7, is provided with a circle of steel sleeve positioning holes 5-1, the steel plate 7 is provided with steel plate positioning holes 7-1, the inner diameters of the steel sleeve positioning holes 5-1 and the steel plate positioning holes 7-1 are 5-20 mm, and the steel sleeve 5 and the steel plate 7 are respectively bound on reinforcement cage stirrups or longitudinal reinforcements of the pier body and the cushion cap 6 through the positioning holes.

The ECC mix proportion in the embodiment is selected and prepared according to the study on the anti-seismic performance test of the high-ductility concrete reinforced concrete beam in the academic paper. Cement: fly ash: river sand: water: 1 of water reducing agent: 1: 0.72: 0.58: 0.01. the volume mixing amount of the PVA fiber is 2% of the volume of the test piece, and the mechanical property of the PVA fiber is as follows: the length is 12mm, the diameter is 0.39mm, the tensile strength is 1600MPa, the elastic modulus is 40GPa, and the elongation is 7 percent; the minimum anchoring length of the CFRP rib is 35d, and when the CFRP rib is connected in a lap joint mode, the lap joint length of a binding joint of the CFRP rib is not less than 1.6 times of the anchoring length; when the CFRP sheet material is pasted, the CFRP sheet material is wrapped and closely pasted along one direction, the head section and the tail section of the CFRP sheet material are fixed in an overlapping mode, and the overlapping length is larger than or equal to 100 mm.

The interface agent in the examples is cement expansive slurry interface agent, and the interface agent mixing ratio is prepared by referring to the utility model patent "a method for reinforcing broken frame joint combined with sheet" (patent number is CN 108798056A). The mixing ratio is cement: secondary fly ash: UEA swelling agent: water 1: 0.1: 0.1: 0.4. the preparation method comprises the steps of firstly carrying out dry mixing on the cement and the secondary fly ash to form dry powder, uniformly mixing the expanding agent and water to form a mixing agent, finally adding the mixing agent into the dry powder, and finally stirring to be in a viscous state.

The utility model is further explained by combining a specific construction process, wherein the construction process of the ECC and reinforced concrete composite pier structure specifically comprises the following steps:

the method comprises the following steps: leveling the place, measuring the unwrapping wire, setting up the scaffold frame, replace into the CFRP muscle with pier part or whole longitudinal reinforcement 3, then carry out the ligature of pier steel reinforcement cage, installation and ligature bucking restraint structure, processing and installation ECC template after that, the high region of pier bottom twice plasticity hinge pours the ECC material and vibrates closely knit, the watering maintenance, it can adjust according to actual conditions to keep in touch with long, nevertheless must not be less than 7 d.

Step two: and (3) carrying out manual roughening treatment on the combined surface of the cured and molded ECC material and the concrete, wherein the coarse aggregate on the surface of the combined surface is exposed to be not less than 6 mm. And then uniformly brushing an interface agent on the joint surface, then processing and installing the pier template, pouring pier body concrete and watering for maintenance.

Step three: cutting and molding the CFRP sheet, cleaning a region of the pier body needing to be adhered with the CFRP sheet, uniformly coating epoxy resin glue, and finally adhering the CFRP sheet 4 and the strip-shaped CFRP sheet to the surface of the pier body; during pasting, the CFRP sheet material is wrapped and closely pasted along one direction, the head and tail sections of the CFRP sheet material are lapped, the lapping length is not less than 100mm, and the construction of the composite pier structure is completed.

While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the utility model as defined in the appended claims.

Claims

1. The utility model provides a ECC and reinforced concrete composite pier structure, includes the pier body and cushion cap (6), its characterized in that: the pier body comprises a reinforced concrete section (2) at the upper part and an ECC material reinforcing section (1) at the lower part, wherein the lower part of the ECC material reinforcing section is connected with a bearing platform (6), a reinforcement cage of the ECC material reinforcing section (1) and a reinforcement cage of the reinforced concrete section (2) are of an integral structure, and part or all longitudinal bars (3) of the pier body are replaced by CFRP bars; a buckling restrained structure is arranged in the ECC material reinforced section (1), a CFRP sheet (4) is coated on the outer surface of the buckling restrained structure, and the buckling restrained structure comprises a steel sleeve (5) and a steel plate (7) welded at one port of the steel sleeve (5); CFRP sheet reinforcing belts (9) are arranged on the outer surface of the reinforced concrete section (2) at intervals.

2. The pier structure compounded by ECC and reinforced concrete according to claim 1, wherein: a sealing rubber cushion layer (8) is arranged on the inner wall of the steel sleeve (5), and the upper end of the sealing rubber cushion layer (8) is 5-25 mm higher than the steel sleeve (5); a circle of steel sleeve positioning holes (5-1) are formed in the end, far away from the steel plate (7), of the steel sleeve (5), steel plate positioning holes (7-1) are formed in the steel plate (7), and the steel sleeve (5) and the steel plate (7) are bound to reinforcement cage stirrups or longitudinal reinforcements of the pier body and the bearing platform (6) respectively through the positioning holes.

3. The pier structure compounded by ECC and reinforced concrete according to claim 1 or 2, wherein: the replacement rate of the CFRP ribs is 25% -100%.

4. The pier structure compounded by ECC and reinforced concrete according to claim 1 or 2, wherein: the CFRP sheet (4) is a material layer which is coated on the outer surface of the ECC material reinforcing section (1) in a pasting mode after epoxy resin glue is coated on the outer surface of the ECC material reinforcing section (1).

5. The pier structure compounded by ECC and reinforced concrete according to claim 1 or 2, wherein: the CFRP sheet reinforcing strips (9) are 5-20 and are equidistantly distributed on the outer surface of the reinforced concrete section (2), the height of each CFRP sheet reinforcing strip (9) is 300-500 mm, and the net distance between every two adjacent CFRP sheet reinforcing strips (9) is 1000-3000 mm.

6. The pier structure compounded by ECC and reinforced concrete according to claim 1 or 2, wherein: the inner diameter of the steel sleeve (5) is larger than the outer diameter of a longitudinal reinforcement cage of the pier body, the steel sleeve is sleeved outside the reinforcement cage, the side length of the steel plate (7) is not smaller than 70d, and d is the diameter of the longitudinal reinforcement.

7. The pier structure compounded by ECC and reinforced concrete according to claim 2, wherein: the inner diameters of the steel sleeve positioning hole (5-1) and the steel plate positioning hole (7-1) are 5-20 mm.