CN104120833A

CN104120833A - Concrete filled steel tube capable of preventing stripping damage

Info

Publication number: CN104120833A
Application number: CN201410395914.2A
Authority: CN
Inventors: 王若林; 朱道佩
Original assignee: Wuhan University WHU
Current assignee: Wuhan University WHU
Priority date: 2014-08-13
Filing date: 2014-08-13
Publication date: 2014-10-29
Anticipated expiration: 2034-08-13
Also published as: CN104120833B

Abstract

The invention discloses a concrete filled steel tube capable of preventing stripping damage. The concrete filled steel tube comprises a steel tube (1) and concrete (2), wherein a geotechnical cloth layer (3) is arranged between the steel tube (1) and the concrete (2); the geotechnical cloth layer (3) is arranged close to the inner wall of the steel tube (1) and connected with the inner wall of the steel tube (1) through structural adhesive (4). The concrete filled steel tube capable of preventing the stripping damage has the advantages that geotechnical cloth high in tensile strength is selected for restraining boundary concrete in the concrete filled steel tube, so that the shrinkage strain of the boundary concrete is reduced, and the fluidity of the dense concrete is not influenced; the geotechnical cloth is closely adhered to the inner wall of the steel tube; the elastic deformation is generated in the presence of the shrinkage strain of the boundary concrete, so that the stripping damage to the concrete filled steel tube is avoided, and the stability and the anti-seismic property of the concrete filled steel tube are improved.

Description

The anti-concrete filled steel tube of peeling off damage

Technical field

The present invention relates to concrete filled steel tube technical field, specifically a kind of anti-concrete filled steel tube of peeling off damage.

Background technology

At bean column node place, the reinforcing bar in beam need to insert in steel core concrete column, and this has brought difficulty to the concrete vibrating in steel core concrete column, in engineering, mostly adopts and builds the self-compacting concrete that need not vibrate.Self-compacting concrete is after sclerosis, and shrinkage strain is larger, the damage of peeling off that therefore can produce steel core concrete column.

At present, mainly in self-compacting concrete, mix expansion agent and reduce concrete shrinkage strain, but the expansion that expansion agent produces all occurs in early days, the later stage still there will be shrinkage phenomenon.The bad control of addition of expansion agent, if incorporation is excessive, the hydrated product of expansion agent, by assembling in concrete, causes local stress excessive, reduces the bearing capacity of concrete filled steel tube; Incorporation is too small, cannot play the effect of compensating concrete contraction strain effect.Another kind of similarly way is to use self-stressing cement, and in this cement, expansion component content is more, and it prevents peeling off damage effect and adding expansion agent similar.

Another kind of way is in self-compacting concrete, to mix contracting agent or polypropylene fibre reduces concrete shrinkage strain, but the part contraction strain that this method can only compensating concrete can not solve and peel off damage problem.Polypropylene fibre mix the mobility that can reduce self-compacting concrete, cause the concrete density of building poor, and then reduce bearing capacity and stability.

Summary of the invention

The object of the invention is to design a kind of anti-concrete filled steel tube of peeling off damage, can reduce concrete contraction strain, effectively reduce and fully fill the steel pipe and the concrete interfacial separation space that because of concrete shrinkage, cause, and significantly do not reduce bearing strength.The intensity of weaving cotton cloth due to geotechnique is high, good springiness, good toughness, thereby improves steel pipe and concrete binding ability, finally reaches and avoids peeling off damage and improving the object of concrete filled steel tube stability and shock resistance of concrete filled steel tube.

The anti-concrete filled steel tube of peeling off damage, comprises steel pipe 1 and concrete 2, is provided with geotechnological layer of cloth 3 between described steel pipe 1 and concrete 2, and described geotechnological layer of cloth 3 is close to steel pipe 1 inwall setting, between geotechnological layer of cloth 3 and steel pipe 1 inwall, by structure glue 4, is connected.

Described geotechnological layer of cloth 3 adopts PFY geotextiles.

The anti-advantage of peeling off the concrete filled steel tube of damage of the present invention is:

1, select the higher geotextiles of tensile strength to retrain border concrete in concrete filled steel tube, reduce the concrete contraction strain in border, and can not affect the mobility of self-compacting concrete.

2, geotextiles and steel pipe inner wall fit tightly, and under the effect of border concrete shrinkage stress, produce elastic deformation, thereby avoid the damage of peeling off of concrete filled steel tube, improve stability and the shock resistance of concrete filled steel tube.

Accompanying drawing explanation

Fig. 1 is steel tube section overall structure schematic diagram of the present invention while being circle.

Fig. 2 is steel tube section overall structure schematic diagram of the present invention while being square.

In figure, 1 is steel pipe, and 2 is concrete, and 3 is geotechnological layer of cloth, and 4 is structure glue.

The specific embodiment

Below in conjunction with accompanying drawing, the present invention is further described: as shown in Figure 1 and Figure 2, the anti-concrete filled steel tube of peeling off damage, comprise steel pipe 1 and concrete 2, between described steel pipe 1 and concrete 2, be provided with geotechnological layer of cloth 3, described geotechnological layer of cloth 3 is close to steel pipe 1 inwall setting, between geotechnological layer of cloth 3 and steel pipe 1 inwall, by structure glue 4, is connected.

Described geotechnological layer of cloth 3 adopts PFY geotextiles.

The present invention is achieved in that

1. the performance parameter of more various structure glue, selects the higher structure glue of tensile strength, thereby guarantees that geotextiles is connected with the firm of steel pipe walls.

2. the performance parameter of more various geotextiles, selects the geotextiles that horizontal resistance to tension is strong, elastic deformation is larger.

3. by structure glue, geotextiles is bonded on steel pipe inner wall, after structure glue is dry stable, concreting, after maintenance a period of time, under gelatification, concrete and geotextiles combine, and the concrete free shrink in border has been produced to constraint.

The performance indications of table 1 PFY geotextiles

Specification (g/m2)	Thickness (mm)	Tensile strength (Mpa)	Modulus of elasticity (Mpa)
				100	0.8	5.63	12.50
150	1.2	9.34	20.83
				200	1.6	12.50	27.78
250	1.9	15.63	34.72
				300	2.2	18.75	41.67
350	2.5	21.88	48.61
				400	2.8	25.63	56.94
450	3.1	28.13	62.50
				500	3.4	31.25	69.44
600	4.2	37.50	83.33
				800	5.5	50.00	111.11

In CECS 28-2012 < < encased structures design and construction standard > >, to the requirement of concrete material, be: the concrete in steel pipe can adopt ordinary concrete and self-compacting concrete, and its strength grade should be lower than C30.

The concrete performance indications of table 2

Strength grade of concrete	Axial tensile strength standard value (Mpa)	Modulus of elasticity ( Mpa)
			C30	2.01	3.00
C35	2.20	3.15
			C40	2.39	3.25
C45	2.51	3.35
			C50	2.64	3.45
C55	2.74	3.55
			C60	2.85	3.60
C65	2.93	3.65
			C70	2.99	3.70
C75	3.05	3.75
			C80	3.11	3.80

From table 1 and table 2, the tensile strength of PFY geotextiles is greater than concrete tensile strength, so geotextiles can be prior to concrete destruction in cooperative work engineering.The modulus of elasticity of PFY geotextiles is much smaller than concrete modulus of elasticity, illustrate that this geotextiles has good elastic deformability, when steel pipe nucleus concrete has enough anti-contractilities in solidification shrinkage process, thereby improve the inwall antistripping damage ability of concrete filled steel tube, and the mechanical property of structure is not made significant difference.In addition, the toughness of geotextiles is good, and plasticity, good toughness can improve the anti-seismic performance of structure.

General concrete filled steel tube concrete label used is C30, and the concrete axle center tensile strength of this intensity is 1.43Mpa, therefore the concrete shrinkage stress in border should be less than 1.43Mpa, otherwise can produce shrinkage crack.Geotextiles elastic strain under the effect of shrinkage stress of filling is larger, has filled on the one hand the space producing due to the concrete contraction strain in border, gives on the other hand border concrete radial bearing reaction, reduces its contraction strain.

Concrete shrinkage stress is less than the tensile strength of structure glue and geotextiles, so there will not be structure glue and geotextiles to be drawn bad situation; Meanwhile, the adhesion stress between geotextiles and steel pipe is greater than concrete shrinkage stress, also there will not be the geotextiles situation separated with steel pipe walls; Thereby avoided the damage of peeling off of concrete filled steel tube.

Claims

1. prevent peeling off the concrete filled steel tube of damage, comprise steel pipe (1) with concrete (2), it is characterized in that: described steel pipe (1) and concrete be provided with geotechnological layer of cloth (3) between (2), (3) described geotechnological layer of cloth is close to (1) inwall setting of steel pipe, (4) (1) (3) geotechnological layer of cloth be connected by structure glue between inwall with steel pipe.

2. the anti-concrete filled steel tube of peeling off damage as claimed in claim 1, is characterized in that: (3) described geotechnological layer of cloth adopts PFY geotextiles.