CN113152775A

CN113152775A - ECC-reinforced steel thin-wall structure and preparation method thereof

Info

Publication number: CN113152775A
Application number: CN202110367687.2A
Authority: CN
Inventors: 陈光明; 李宁景; 赵程; 柳钦; 赵新宇; 李召兵; 胡福南; 刘伟楠
Original assignee: Guangzhou Public Utilities Planning And Design Institute Co ltd; South China University of Technology SCUT
Current assignee: Guangzhou Public Utilities Planning And Design Institute Co ltd; South China University of Technology SCUT
Priority date: 2021-04-06
Filing date: 2021-04-06
Publication date: 2021-07-23

Abstract

The invention relates to an ECC (error correction code) enhanced steel thin-wall structure which comprises an ECC layer and a steel thin-wall layer which are arranged from outside to inside in sequence; arranging an enhancement grid inside the ECC layer; the steel thin-wall structure is a closed structure with a cavity or an open structure with an opening. And also relates to a preparation method of the ECC-reinforced steel thin-wall structure. The ECC layer can restrain the steel thin-wall layer to prevent the steel thin-wall layer from local buckling, and is used as a fire-resistant and durable protective layer of the steel thin-wall layer; the steel thin-wall layer on the inner side is used as a rigid framework and a template for pouring the ECC layer on the outer side, and plays a role in enhancing the rigidity of the ECC layer and sharing load; the two-layer structure works cooperatively, so that the steel thin-wall structure has better stress performance, fire resistance and durability, and belongs to the technical field of building structures.

Description

ECC-reinforced steel thin-wall structure and preparation method thereof

Technical Field

The invention relates to a building structure, in particular to an ECC (error correction code) reinforced steel thin-wall structure and a preparation method of the ECC reinforced steel thin-wall structure.

Background

In recent decades, steel structures have been widely used in high-rise buildings and bridge engineering due to their advantages of light weight, high strength, convenient construction, etc., and have achieved good economic benefits. The steel thin-wall structure just utilizes the characteristic, and steel is made into a thin-wall structure form, so that the steel structure is lighter and the material consumption is less. However, in practical engineering, the thin-walled steel structure still has the defects of easy local buckling, poor fire resistance, insufficient corrosion resistance and the like.

ECC (engineered Cementitious composite) is one of the high-performance fiber-toughened cement-based composite materials which have been rapidly developed in recent decades, and has super-strong crack control capability, bending toughness, fatigue resistance and durability. Currently, ECC has been successfully applied to many projects in various countries around the world and has achieved good results. As the ECC contains the chopped fibers, the ECC can play a good bridging role, not only has excellent tensile deformation capacity (the strain energy reaches more than 3 percent), but also has good crack dispersion and control capacity (the cracks are controlled within 100 mu m), so that the overall force transmission performance of the material is not weakened. In addition, research also shows that when the chopped fibers in the ECC are PVA fibers, the chopped fibers can be gradually melted at high temperature to form communicated gaps in the ECC, so that the release of the internal steam water pressure is facilitated, the ECC is not easy to burst, and the integrity of the ECC at high temperature is maintained. Therefore, the ECC is used as the structure surface layer, so that the fire resistance of the structure can be enhanced, the degradation effect of corrosion environment erosion on the structure material can be reduced due to the good crack control capability of the structure, and the later maintenance cost is reduced. In addition, industrial waste is largely used in raw materials required for preparing ECC, so that ECC is also a green and environment-friendly building material.

Disclosure of Invention

Aiming at the technical problems in the prior art, the invention aims to: the ECC-reinforced steel thin-wall structure and the preparation method thereof are provided, and the rigidity of the thin-wall structure can be enhanced and the load can be shared.

In order to achieve the purpose, the invention adopts the following technical scheme:

an ECC-enhanced steel thin-wall structure comprises an ECC layer and a steel thin-wall layer which are sequentially arranged from outside to inside; arranging an enhancement grid inside the ECC layer; the steel thin-wall structure is a closed structure with a cavity or an open structure with an opening. The thickness of the thin steel wall layer is 2mm-40 mm.

Preferably, when a closed structure is used, the number of chambers is one.

Preferably, when a closed structure is adopted, the number of the chambers is at least two, the chambers are separated by a partition plate, and the material of the partition plate is the same as that of the steel thin-wall layer.

Preferably, when an open structure is adopted, the number of the openings is at least one, and the openings are arranged on the side wall of the steel thin-wall structure.

Preferably, the reinforcing mesh is one or more of a fiber woven mesh, an frp (fiber reinforced polymer) mesh and a grid.

Preferably, welding nails are fixed on the outer side of the steel thin-wall layer and are arranged in a rectangular array, and the distance between the welding nails is an integral multiple of the grid spacing of the reinforcing grid; the reinforcing grid is bound on the welding nails through iron wires.

Preferably, the geometric centroids of the cross sections of the ECC layer and the steel thin-wall layer coincide.

Preferably, the cross-sectional shape of the steel thin wall layer is circular, elliptical, rectangular or regular polygonal.

Preferably, the ECC layer with the same thickness is wrapped on the outer side of the steel thin-wall layer, or the ECC layer with the variable thickness is wrapped on the outer side of the steel thin-wall layer; the steel thin-wall layer is arranged in equal thickness or variable thickness.

A preparation method of an ECC (error correction code) enhanced steel thin-wall structure comprises the following steps of firstly, fixing welding nails outside a steel thin-wall layer; secondly, fixing the reinforced grids on the welding nails; thirdly, arranging a template outside the steel thin-wall layer and temporarily fixing the template; fourthly, pouring the ECC layer between the steel thin-wall layer and the template; and fifthly, demolding.

In summary, the present invention has the following advantages:

1. the invention has good stress performance. The ECC has strong ultimate tensile deformation capability, and the ECC layer wrapped on the outer side of the steel thin-wall layer can be deformed and stressed together with the steel thin-wall layer under the embedding action of the welding nail; the larger rigidity and shear strength of the steel thin-wall layer make up the defects of the ECC layer in the aspects of rigidity and shear resistance when the ECC layer is stressed independently; on the other hand, the ECC layer can restrict the inner steel thin-wall layer to prevent the latter from being locally unstable outwards, which is beneficial for the steel thin-wall layer to fully exert the material strength thereof, so that the bearing capacity and the ductility of the double-layer combined structure of the invention are obviously higher than the superposition of two material layers. Thus, the combination of the steel wall layer with the ECC layer will result in a force effect of 1+1>2, i.e. the combined effect of the ECC layer and the steel wall layer is greater than the sum of the individual effects of the two.

2. The invention has good fire resistance. The PVA fiber contained in the ECC has a lower melting point, can be melted at high temperature to form a water vapor channel, is favorable for the discharge of the internal steam water pressure, enables the ECC to have good fire resistance, can not burst at high temperature, and can effectively improve the fire resistance of the steel thin-wall layer.

3. The invention has good durability. The outer ECC layer has excellent crack control capability, the crack width can be controlled within 100 mu m, an external corrosive medium is difficult to penetrate through the ECC layer to reach the surface of the steel thin-wall layer to cause corrosion, the durability of the steel thin-wall layer is well protected, the cost for later maintenance of the steel thin-wall layer is reduced, and the durability of the steel thin-wall layer in severe environments (such as outdoor exposure environment, coastal environment and marine environment) can be effectively improved.

4. The invention is convenient for construction. When the method is implemented, only welding nails are needed to be welded outside the steel thin-wall layer, the fiber woven mesh or FRP grid or grating is hung on the welding nails and fixed by thin iron wires, a wood template or GFRP pipe is used as an outer template, then ECC (error correction code) is poured and the template is removed, and the manufactured steel thin-wall structure can be directly used as a structural member or a structural component, and has light weight and convenient construction.

5. Compared with a single-cavity structure, the internal steel structures in the multiple cavity structures can not only share the stress of the outer steel thin-wall structure and disperse and reduce the stress of the outer steel thin-wall structure, but also form support for the outer steel thin-wall structure, so that the outer steel thin-wall structure is not easy to be unstable inwards, the integral bearing capacity of the double-layer structure is increased, and the deformation of the double-layer structure is reduced.

Drawings

FIG. 1 is a schematic cross-sectional view of an ECC-enhanced steel thin-walled structure with one chamber.

FIG. 2 is a schematic cross-sectional view of an ECC-enhanced steel thin-walled structure with three chambers;

FIG. 3 is a perspective view of an ECC-enhanced steel thin-walled structure.

FIGS. 4a-4e are schematic cross-sectional views of the steel wall in the steel wall layer.

Fig. 5a-5e are construction process diagrams of an ECC layer and a reinforcing mesh outside a steel thin-wall layer.

Fig. 6 is a perspective view of the connection of the reinforcing grid to the weld nail.

Fig. 7 is a schematic view of the connection of the reinforcing grid to the weld nail.

Fig. 8 is a schematic view of the overlapping portion of the reinforcing mesh.

Fig. 9a-9b are enlarged partial views of the reinforcement grid and the weld nail bound by thin iron wires.

Fig. 10 is a schematic structural view of the welding nail.

Wherein: 1 is an ECC layer, 2 is a reinforcing grid, 3 is a steel thin-wall layer, and 4 is a cavity; 5 are the welding nails, 6 are the connected node, 7 are thin iron wire, 8 are the baffle, and L is overlap joint length.

Detailed Description

The present invention will be described in further detail with reference to specific embodiments.

Example one

An ECC-enhanced steel thin-wall structure comprises an ECC layer and a steel thin-wall layer which are sequentially arranged from outside to inside; arranging an enhancement grid inside the ECC layer; the steel thin-wall structure is a closed structure with a cavity or an open structure with an opening. The thickness of the thin steel wall layer is 2mm-40 mm. In this example, the thickness of the steel thin-walled layer was 10 mm.

When a closed structure is employed, the number of chambers is one. In this embodiment, the number of chambers is one.

The reinforced grid is one or more of fiber woven mesh, FRP (fiber reinforced polymer) grid and grid. Welding nails are fixed on the outer side of the steel thin-wall layer and are arranged in a rectangular array, and the distance between the welding nails is an integral multiple of the grid spacing of the reinforced grid; the reinforcing grid is bound on the welding nails through iron wires. The reinforcing mesh of this embodiment is a woven fiber mesh. The distance between the welding nails is equal to the lattice spacing of the reinforced grids, the edges of the adjacent reinforced grids are mutually overlapped, and the overlapping length L is 2-3 times of the lattice spacing of the reinforced grids. The manufactured steel thin-wall structure can be directly used as a structural member or a structural component, and has light weight and convenient construction.

The geometric centroids of the cross sections of the ECC layer and the steel thin-wall layer are coincident.

In the steel thin wall layer, the cross section of the steel thin wall is in a circular shape, an oval shape, a rectangular shape or a regular polygon shape. The steel thin wall of the present example has a rectangular cross-sectional shape.

The ECC layer with the same thickness is wrapped on the outer side of the steel thin-wall layer, or the ECC layer with the variable thickness is wrapped on the outer side of the steel thin-wall layer; the steel thin-wall layer is arranged in equal thickness or variable thickness. In this embodiment, the ECC layer is wrapped on the outer side of the steel thin-wall layer in the same thickness, and the steel thin-wall layer is set in the same thickness.

In this embodiment, the ECC layer is wrapped around the outer side of the steel thin-wall layer to form a cube, and the cross-sectional shape of the cavity is rectangular.

The invention has good stress performance. The ECC has strong ultimate tensile deformation capability, and the ECC layer wrapped on the outer side of the steel thin-wall layer can be deformed and stressed together with the steel thin-wall layer under the embedding action of the welding nail; the larger rigidity and shear strength of the steel thin-wall layer make up the defects of the ECC layer in the aspects of rigidity and shear resistance when the ECC layer is stressed independently; on the other hand, the ECC layer can restrict the inner steel thin-wall layer to prevent the latter from being locally unstable outwards, which is beneficial for the steel thin-wall layer to fully exert the material strength thereof, so that the bearing capacity and the ductility of the double-layer combined structure of the invention are obviously higher than the superposition of two material layers. Thus, the combination of the steel wall layer with the ECC layer will result in a force effect of 1+1>2, i.e. the combined effect of the ECC layer and the steel wall layer is greater than the sum of the individual effects of the two.

Example two

When a closed structure is adopted, the number of the chambers is at least two, the chambers are separated by a partition plate, and the material of the partition plate is the same as that of the steel thin-wall layer. In this embodiment, the steel thin-walled structure adopts closed structure, and the quantity of cavity is three, separates through the baffle between the cavity, and the material of baffle is with steel thin-walled layer. The enhanced mesh of this embodiment is an frp (fiber reinforced polymer) mesh.

Fiber Reinforced composite (FRP), CFRP, GFRP, AFRP, BFRP and the like. Light weight, hardness, non-conductivity, high mechanical strength, less recovery and corrosion resistance.

In this embodiment, the cross-sections of the three chambers are all rectangular, and the sizes of the three chambers are consistent.

In the steel thin-wall structure of the embodiment, the ECC layer can restrain the inner steel thin-wall layer to prevent the steel thin-wall layer from local buckling, and at the same time, the ECC layer serves as a fire-resistant and durable protective layer of the steel thin-wall layer; the inner steel thin-wall layer is used as a rigid framework and a template for pouring the outer ECC layer, the three chambers are separated by the partition plate to share the stress of the outer steel thin-wall structure, the stress is dispersed and reduced, and the outer steel thin-wall structure can be supported to be not easy to be unstable inwards, so that the integral bearing capacity of the double-layer structure is increased, and the deformation of the double-layer structure is reduced. The two layers of structures work cooperatively, so that the steel thin-wall structure has better stress performance, fire resistance and durability, and has wide application prospect in bridge structures and ocean engineering structures in exposed corrosive environments.

The embodiment is not described in the first embodiment.

EXAMPLE III

In this embodiment, the ECC layer is wrapped on the outer side of the steel thin-wall layer in a variable thickness manner, and the steel thin-wall layer is set in a variable thickness manner. The ECC layer of the embodiment is wrapped on the outer side of the steel thin-wall layer in a variable thickness mode, and when the ECC layer on the outer side is thick enough, the local bending rigidity is high, so that the outward local buckling of the steel pipe can be effectively prevented. The steel thin-wall layer is set in a variable thickness mode, the thickness of the steel thin-wall layer is correspondingly changed according to the thickness change of the ECC layer, the ECC layer is matched with the constraint of the steel thin-wall layer on the steel thin-wall layer, and the change of internal stress is avoided, so that the problems that the strength of the steel thin-wall structure is not high enough and the rigidity of the steel thin-wall structure is not large enough when the steel thin-wall structure is independently pressed are solved.

The embodiment is not described in the first embodiment.

Example four

When an open structure is adopted, the number of the openings is at least one, and the openings are arranged on the side wall of the steel thin-wall structure. In this embodiment, the steel thin-walled structure adopts open structure, and the quantity of opening is one, sets up the lateral wall at steel thin-walled structure. The steel thin-wall structure of the embodiment only fills other materials in the steel thin-wall layer when needed, provides more design choices for practical engineering application, and has light weight and convenient transportation and construction.

The embodiment is not described in the first embodiment.

The invention has the advantages and effects that:

compared with a combined column component which is formed by an ECC material, a steel reinforcement framework poured in the ECC material, a steel pipe, a UHPC material poured on the inner wall of the steel pipe and a cavity from outside to inside, the combined column component has the structure that an ECC layer and a steel thin-wall layer are sequentially arranged from outside to inside;

the combined column component adopts a centrifugal forming process to manufacture the UHPC layer in the steel pipe, and only can adopt a round structural steel pipe with a single cavity, so that the two structures have great difference. The invention has good stress performance. The ECC has strong ultimate tensile deformation capability, and can be wrapped on the outer side of the steel thin-wall layer to cooperatively deform with a steel structure to share the load of the steel thin-wall layer, so that the ECC has higher bearing capability and ductility than the steel thin-wall layer; the ECC layer can also restrain the inner steel thin-wall layer to prevent the inner steel thin-wall layer from local buckling, and the steel thin-wall layer can fully exert the strength of the inner steel thin-wall layer.

The enhanced grids are arranged in the ECC layer, have corrosion resistance compared with the combined column component, and can have better durability in severe environments (outdoor exposure, coastal environments and marine environments).

From the aspect of construction process: the construction process is simpler, the composite column member can be prefabricated at one time in a factory and then conveyed to a construction site for use, the application is convenient, the UHPC layer is manufactured in the steel pipe and autoclaved and maintained by the centrifugal forming process needed by the composite column member, ECC is required to be sprayed after field installation, and the process is complex.

In addition to the above embodiments, the ECC layer may be replaced with one of a fiber reinforced resin based composite material layer (FRP layer), an Ultra High Performance Concrete (UHPC) layer, a geopolymer concrete (or mortar) layer, an alkali activated concrete (or mortar) layer, and a polypropylene fiber reinforced concrete (or mortar) layer, if necessary. These variations are all within the scope of the present invention.

In addition to the above embodiments, the thin steel wall in the thin steel wall layer may have the cross-sectional shapes shown in fig. 4a-4e, and these variations are within the scope of the present invention.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. An ECC-enhanced steel thin-walled structure, characterized in that: the device comprises an ECC layer and a steel thin-wall layer which are arranged from outside to inside in sequence; arranging an enhancement grid inside the ECC layer; the steel thin-wall structure is a closed structure with a cavity or an open structure with an opening.

2. An ECC-reinforced steel thin-walled structure according to claim 1, characterized in that: when a closed structure is employed, the number of chambers is one.

3. An ECC-reinforced steel thin-walled structure according to claim 1, characterized in that: when a closed structure is adopted, the number of the chambers is at least two, the chambers are separated by a partition plate, and the material of the partition plate is the same as that of the steel thin-wall layer.

4. An ECC-reinforced steel thin-walled structure according to claim 1, characterized in that: when an open structure is adopted, the number of the openings is at least one, and the openings are arranged on the side wall of the steel thin-wall structure.

5. An ECC-reinforced steel thin-walled structure according to claim 1, characterized in that: the reinforced grid is one or a combination of fiber woven mesh, FRP grid and grid.

6. An ECC-reinforced steel thin-walled structure according to claim 5, characterized in that: welding nails are fixed on the outer side of the steel thin-wall layer and are arranged in a rectangular array, and the distance between the welding nails is an integral multiple of the grid spacing of the reinforced grid; the reinforcing grid is bound on the welding nails through iron wires.

7. An ECC-reinforced steel thin-walled structure according to claim 1, characterized in that: the geometric centroids of the cross sections of the ECC layer and the steel thin-wall layer are coincident.

8. An ECC-reinforced steel thin-walled structure according to claim 1, characterized in that: in the steel thin wall layer, the cross section of the steel thin wall is in a circular shape, an oval shape, a rectangular shape or a regular polygon shape.

9. An ECC-reinforced steel thin-walled structure according to claim 1, characterized in that: the ECC layer with the same thickness is wrapped on the outer side of the steel thin-wall layer, or the ECC layer with the variable thickness is wrapped on the outer side of the steel thin-wall layer; the steel thin-wall layer is arranged in equal thickness or variable thickness.

10. Method for producing an ECC-reinforced steel thin-walled structure according to any of claims 1 to 9, characterized in that: comprises the following steps of (a) carrying out,

firstly, fixing welding nails outside a steel thin-wall layer;

secondly, fixing the reinforced grids on the welding nails;

thirdly, arranging a template outside the steel thin-wall layer and temporarily fixing the template;

fourthly, pouring the ECC layer between the steel thin-wall layer and the template;

and fifthly, demolding.