CN1083887A - Nonseam design construction method of super-long reinforced concrete structure - Google Patents

Abstract

Overlength reinforced concrete structure seamless design construction technology of the present invention, it is shrinkage stress curve according to structure, at the big position of contraction expansion reinforcing band is set, be made into the concrete (its limited expansion rate is 4～6%) of big expansion with the expansive cement of the expansion agent of higher volume or big cement consumption, with the shrinkage stress of compensating concrete by special job practices, replace shrinkage joint and last-cost joint with expansion reinforcing band, realize the continuous concrete placing construction.

Description

Nonseam design construction method of super-long reinforced concrete structure

The present invention relates to building construction technology, particularly cast-in-situ steel reinforced concrete seamless design construction technology.

For continous way cast-in-situ steel reinforced concrete super-long structural, in order to control the crack, regulation is provided with the shrinkage joint in the design, also often adopts last-cost joint during construction, in order to discharge the concrete internal stress.(GBJ10-89) maximum spacing at reinforced concrete structure shrinkage joint there is clearly regulation (seeing Table 1) as China's national standard " Code for design of concrete structures ".The shrinkage joint spacing of former Soviet Union's standard continous way structure is in person 40m in the indoor and soil.

Reinforced concrete structure shrinkage joint maximum spacing (m)

Table 1

Structured sort		In indoor or native	In the open
				Bent structure	Assembling	100	70
Frame construction	Assembling	75	50
				Cast-in-situs type	55	35
	Shear wall structure	Assembling	65				40
Cast-in-situs type				45	30
		Class formation such as retaining wall, basement wall	Assembling			40	30
Cast-in-situs type	30			20

Open-air person 25m.Preceding Germany reinforced concrete structure regulations DIN1045 there is no concrete regulation for the shrinkage joint spacing, but generally gets 30m in PRACTICE OF DESIGN.Some diaphragm wall formula structure designs of France adopt the shrinkage joint spacing of 30～40m.The designer of the U.S. and Japan determines rational shrinkage joint spacing according to the experience of oneself with calculating usually.Adopt shrinkage joint and last-cost joint, Crack Control is rather gathered effects, but the processing of seam trouble, construction complexity, structural integrity variation, claim for eot.

Task of the present invention is technology cancellation shrinkage joint and the last-cost joint by " expansion reinforcing band ", and the continuous construction of concrete once survives.This design and construction of having cancelled shrinkage joint and last-cost joint are referred to as " seamless design construction method ".

The present invention is the shrinkage stress curve according to structure, at the big position of contraction expansion reinforcing band is set, be made into the concrete (its limited expansion rate is 4～6%) of big expansion with the expansive cement of the expansion agent of higher volume or big cement consumption, with the shrinkage stress of compensation concrete.Replace former shrinkage joint and last-cost joint by continuous pouring with expansion reinforcing band.

The setting of expansion reinforcing band and structure are seen accompanying drawing 1 and accompanying drawing 2.Accompanying drawing 1 is the jointless construction schematic diagram when waterproof requirement is arranged, and wherein indicates swelling stress curve 1, wire gauze 2, little expansion rate concrete 3, shrinkage stress curve 4, expansion reinforcing band 5.Accompanying drawing 2 is the jointless construction schematic diagram during for no waterproof requirement, wherein indicates swelling stress curve 1, wire gauze 2, ordinary concrete 3, shrinkage stress curve 4, expansion reinforcing band 5.For the continous way monolithic reinforced concrete structure, do not require the structure position of waterproof, every 25～30m an expansion reinforcing band is set.Described bandwidth 2m, the both sides of this band hang up close hole wire gauze, and the aperture of net is 10mm, and purpose is to stop the stone in the concrete to pass through.Rebar ratio improves 20% in this band, and concrete adopts big expansion rate concrete (available expansive cement or expansion agent configuration form) in this band, and its limited expansion rate is controlled at 4～6 * 10 ^-4Scope in, concrete strength is not less than its both sides concrete strength in this band.

To the structure of no waterproof requirement, expansion reinforcing band both sides concrete is an ordinary concrete; To the structure of waterproof requirement is arranged, these band both sides are little expansion rate concrete (compensate for shrinkage concrete), and its limited expansion rate is controlled at 2～4 * 10 ^-4

During construction, determine the position of expansion reinforcing band earlier, and hang up wire gauze that concrete when watering reinforcing band is used big expansion concrete from advancing on one side, reinforcing band waters complete, uses former proportioning concrete again instead, and shrinkage joint or last-cost joint are not stayed in so continuous pouring, and once construction finishes.

Theoretical foundation of the present invention is described below:

According to concrete shrinkage joint distance computation formula:

$\left(L\right)=1.5\sqrt{\frac{H\·E}{C_x}}\·\mathrm{ar}\cosh \frac{\left|\mathrm{aT}\right|}{\left|\mathrm{aT}\right|-{\mathrm{\ϵ}}_p}---\left(1\right)$

In the formula: the calculated thickness of H-concrete plate or wall or height

ε _pThe ultimate elongation of-concrete, (* 10 ^-4)

The modulus of elasticity of E-concrete, (* 10 ⁴MPa)

The Cx-ground is to the constraint factor of concrete, (N/mm ³)

α-concrete linear expansion coeffcient, (10 * 10 ^-6)

T-concrete linear expansion coeffcient, (10 * 10 ^-6)

The T-integrated temperature (℃)

The inverse function of arcosh-hyperbolic cosine

This formula calculates the shrinkage joint spacing with ultimate deformation.By following formula as seen, when | α T| → ε p, arcosh → ∞ need not the shrinkage joint fully.This just needs to reduce temperature or contraction, or improves the ultimate elongation ε p of concrete.The raising of concrete ε p value is very difficult, shrinks and the heat of hydration temperature difference so be conceived to reduce, and according to T=ε y/ α, concrete expansion rate ε y is 1 * 10 ^-4The time, can reduce temperature T=(1 * 10 ^-4)/(10 * 10 ^-6)=10 ℃.

With U type concrete expansion agent (UEA) is example.UEA is a kind of expansion agent that China Building Materials Academy succeeds in developing, and mixes 10～15%UEA in cement, can obtain the expansion concrete of different compressive pre-stresses, different expansion rates.

If the long 100m of concrete works, wide 100m, thick 2m.Works waters on plain concrete face, and horizontal resistance coefficient Cx gets 1.0N/mm ³, bullet mould E=1.5 * 10 of concrete in the time of 14 days ⁴, ultimate elongation ε p=2.5 * 10 ^-4(consideration is crept).60 ℃ of concrete center maximum temperatures, 30 ℃ of environment average temperatures.Ordinary concrete was 14 days shrinkage value ε y=1.5 * 10 ^-4, and UEA compensate for shrinkage concrete is ε at 14 days swell value ₂=2.5 * 110 ^-4(mixing 10-12% in the UEA).Calculate shrinkage joint maximum spacing (seeing Table 2) according to formula (1).

Calculate as seen from contrast, ordinary concrete makes the comprehensive temperature difference reach 45 ℃, α T＞ε p owing to 15 ℃ of the flexible equivalent temperature difference that causes, when length surpasses 10.6m, building will ftracture, and the UEA concrete is because expansion can compensate 25 ℃ of concrete temperatures, make the comprehensive temperature difference be kept to 5 ℃, α T＜ε p, (L) → ∞ is not so random length can be stayed the shrinkage joint.

In brief, the expansion concrete is owing to the compensate for shrinkage effect has crack resistance, set up the 0.4-1.0MPa compressive pre-stress in the band by being arranged on of expansion reinforcing band, thereby offset concrete whole or most of tensile stresss in hardening process, improve the stress-strain state of ordinary concrete inside, make maximum strain in the works less than the ultimate extension value of concrete, reach the purpose of overlength reinforced concrete structure Crack Control.

Embodiment 1:

Certain builds long 90m, wide 90m, underground two layers, 12 layers on the ground." # " word last-cost joint is established in former design from top to bottom, and construction is trouble very.The seamless technology of back trial edition changes # word last-cost joint into # font expansion reinforcing band, and basement bottom board, abutment wall and each floor plate, shear wall, beam all are to water a jar concrete continuously, realizes jointless construction.Basement was observed through 3 years, did not split and did not ooze.The building wallboard was observed not have through 1 year and is split.This project zone of swelling is to realize that by mixing UEA volume is 14% in the UEA.

Embodiment 2:

The long 75m of certain highrise building, wide 10m, 12 layers on the ground, be the frame-shear wall structure, two road last-cost joints are adopted in former design, and the back seamless technology of UEA concrete on probation is implemented at floor, shear wall and beam, former two road last-cost joints, other parts ordinary concrete have been replaced with three roads UEA concrete expansion reinforcing band (wherein the UEA volume 15%).1 year on probation, the concrete globality was good on inspection, does not find shrinkage crack, greatly accelerating construction progress.

Table 2

Project	Ordinary concrete	UEA compensate for shrinkage concrete
			Concrete internal-external temperature difference T 1	60-30=30℃	60-30=30℃
Concrete expansion rate ε	εy=1.5×10 -4(negative value)	ε 2＝2.5×10 -4(on the occasion of)
			Concrete shrinks equivalent temperature difference T 2	εy/α=1.5×10 -4/10×10 -6=15 ℃ (on the occasion of)	(2.5×10 -4/10×10 -6)=25 ℃ (negative value)
Comprehensive temperature difference T	T 1+T 2=30+15=45℃	30-25=5℃
			Ultimate elongation ε P	2.5×10 -4	2.5×10 -4
arcosh(｜αT｜/｜αT｜-εP)	0.52	αT＜εp,∞
			〔L〕	10.6m	∞

The present invention is a significant innovation for design of overlength steel bar concrete cast-in-place structural and construction, can cancel shrinkage joint and last-cost joint, and concrete once waters, and accelerates the duration progress greatly, convenient construction, and concrete structural integrity and crack resistance are good.

The present invention in Beijing, ground such as Tianjin, Guangzhou, Shenzhen tries out, respond well, technical economic benefit is obvious, is subjected to design, construction and Construction unit and extensively welcomes.

Claims (2)

1, a kind of Nonseam design construction method of super-long reinforced concrete structure, it is characterized in that: according to the shrinkage stress curve of structure, at the big position of contraction expansion reinforcing band is set, flexible and the last-cost joint that replaces employing in the construction in the past by the mode of continuous pouring with expansion reinforcing band, wherein said continuous pouring is the position of determining zone of swelling earlier, hang up the aperture in the both sides of 2 meters wide zone of swelling and be wire gauze less than 10mm, concrete is from advancing on one side, when watering expansion reinforcing band, use big expansion concrete instead, after this band waters and finishes, use former proportioning concrete again instead, so continuous pouring, being defined as of described expansion reinforcing band position do not require that the structure position of waterproof is provided with an expansion reinforcing band every 25～30m, and the both sides concrete of this band is an ordinary concrete, and the structure position that waterproof requirement is arranged is provided with an expansion reinforcing band every 40～50m, the both sides concrete of this band is little expansion rate concrete, and its limited expansion rate is controlled at 2～4 * 10 ^-4, described expansion reinforcing band is the big expansion rate concrete that is mixed with expansion agent or expansive cement, its limited expansion rate is controlled at 4～6 * 10 ^-4Scope in, reinforcing bar is joined rate and will be improved 20% in this band, the intensity of its concrete is not less than the intensity of its both sides concrete.

2, seamless design job practices according to claim 1, it is characterized in that: described concrete expansion agent is a U type concrete expansion agent, its incorporation is 13～15% of a cement consumption for big expansion rate concrete, and its incorporation is 10～12% of a cement consumption for little expansion rate concrete.

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