CN101614053A - High flexibility pre-pressing method pre-stress steel bar and its implementation - Google Patents
High flexibility pre-pressing method pre-stress steel bar and its implementation Download PDFInfo
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- CN101614053A CN101614053A CN200910054610A CN200910054610A CN101614053A CN 101614053 A CN101614053 A CN 101614053A CN 200910054610 A CN200910054610 A CN 200910054610A CN 200910054610 A CN200910054610 A CN 200910054610A CN 101614053 A CN101614053 A CN 101614053A
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Abstract
A kind of high flexibility pre-pressing method pre-stress steel bar and its implementation, it penetrates reinforced bar stretching, surpassing under the axial compression effect of critical force the balance that the minor bending shape that leans on tension reinforcing steel bar with eccentric side slightly replaces the straight line of central compression, just can make the pressure of big flexibility depression bar greater than critical force, and obvious press-bending does not take place, become the strength problem of combined deformation.Described deformation of member form is the combination of axial compression (or stretching) and pure bending, and the member pulling anchor cable stage is in the small deformation elastic stage, and erection stage is in elastic stage.Set up the line of deflection and the stress equation of unit construction distortion simultaneously, can find the solution other condition, thereby member is carried out Cross section Design and bearing capacity is checked from known conditions.The present invention is without additional constraint, so special measure is not taked in construction, common method is taked in stretch-draw, anchoring and installation.The present invention does not have the unstability restriction, and length is big, and the cross section is little, and lateral stressed bending is out of shape slightly during pre-applied force freely, can connect lengthening piecemeal.
Description
Technical field
The present invention relates to a kind of prepressed method prestressed reinforcement, particularly a kind of pressure surpasses the prepressed method prestressed reinforcement of big flexibility Critical Force of Compressed Bar.
Background technology
The prepressed method prestressed reinforcement is a kind ofly to penetrate the stressed in advance empty stomach depression bar of reinforcing bar by stretch-draw and anchoring before the structure of packing into.Stressed empty stomach depression bar is cast in the structural concrete, treats that concrete reaches will penetrate the reinforcing bar unloading behind the prescribed strength, d/d power just acting in opposition in whole bearing structure.
The steel pipe that nineteen fifty Englishman K Pierre uncommon (KBillig) proposes to hold out against mutually with several joints is formed a precompressed element, and penetrates cable wire in steel pipe, carries out precompressed by the anchor head plate that is fixed on the steel pipe two ends.
Nineteen fifty-two German FW horse Dare (FWMader) proposes to serve as the precompressed element with a straight hollow profile steel and puts into bearing structure, carries out precompressed on the pressure-bearing pedestal.
The Yuan Guo of Tongji University does and proposes high-tensile steelo bars are penetrated in the high tensile steel tube of slightly larger in diameter, the stretch-draw bar reinforcement, and an anchor is rolled in utilization makes steel pipe produce compressive pre-stress.
Above prepressed method prestressed reinforcement adopts the straight line balance mode, and service condition is restricted.Pierre's invention uncommon and the horse Dare needs pedestal to carry out precompressed.The invention steel pipe that Yuan Guo does can not be oversize.Have only axial compression to be no more than critical force, the elongated center compressed straight bars just can unstability.
The flexibility of depression bar or title slenderness ratio, it is worth big more easy more unstability.When the flexibility of depression bar can be calculated critical force (unstability becomes the limit of proportionality that stress before curved is no more than material) greatly with Euler's formula to the central compression straight-bar, then be referred to as big flexibility depression bar, be sometimes referred to as elongated depression bar.When reaching critical force, the loss of equilibrium stability under the depression bar straight axis shape.
Summary of the invention
The object of the present invention is to provide a kind of high flexibility pre-pressing method pre-stress steel bar and its implementation, flexural deformation does not increase rapidly when making pressure surpass critical force, line of deflection near linear shape, and the supporting capacity of depression bar is greater than elongated center compressed straight bars critical force.
For reaching above purpose, solution of the present invention is:
Take to be different from the mode of prior art: pulling anchor cable stage is not an equilibrium conditions with without acceptance of persons straight axis, and lean on the eccentric slightly little curved state of tension reinforcing steel bar with linear state forfeiture back compressive pre-stress reinforcing bar inwall side is equilibrium conditions, the stress and the distortion of the stress of consideration member pure bending and distortion and axial compression (or stretching) are superimposed, and unit construction is out of shape the elastic range of limitting at small deformation.
A kind of prepressed method prestressed reinforcement, it is equilibrium conditions that pulling anchor cable stage compressive pre-stress reinforcing bar and tension reinforcing steel bar lean on the eccentric slightly little curved state of tension reinforcing steel bar with linear state forfeiture back compressive pre-stress reinforcing bar inwall side without acceptance of persons.
Pressure is greater than the critical force of big flexibility compressive pre-stress reinforcing bar, and deformation of member form is the combination of axial compression/stretching and pure bending.
For inserting very loose easily matched in clearance, leave certain interval between the two between compressive pre-stress reinforcing bar and the tension reinforcing steel bar.
Straight-bars such as described compressive pre-stress reinforcing bar and tension reinforcing steel bar employing.
Described compressive pre-stress reinforcing bar adopts steel pipe, and tension reinforcing steel bar adopts steel strand.
The joint of described compressive pre-stress reinforcing bar adopts the dry joint form of prestressed member.
The centering of two vertical round steel pipe of butt during described compressive pre-stress bar splice, the anchor clamps of steel plate, top suitable v block are fixed below adopting.
The member pulling anchor cable stage is in the small deformation elastic stage, and erection stage is in elastic stage while joint and must not ftractures.
The deformation formula of member axial compression of the present invention (or stretch) and pure bending is led from the differential equation of Hooke's law and beam line of deflection respectively, utilizes the relation of stress and distortion to try to achieve stress, utilizes principle of stacking to try to achieve combined deformation.Set up the line of deflection and the stress equation of unit construction distortion simultaneously, can find the solution other condition from known conditions, thereby to the compressive pre-stress reinforcing bar with tension reinforcing steel bar carries out Cross section Design and bearing capacity is checked.
A kind of implementation method of prepressed method prestressed reinforcement, it may further comprise the steps:
1) selected each parameter value that calculates tension reinforcing steel bar and compressive pre-stress reinforcing bar that reaches;
2) tension reinforcing steel bar penetrates compressive pre-stress reinforcing bar duct;
3) tension reinforcing steel bar that stretches out as the stretch-draw of the afterburning pedestal centering of jack of compressive pre-stress reinforcing bar;
4) with the work ground tackle tension reinforcing steel bar is anchored at two ends, with the compressive pre-stress reinforcing bar structure pressure zone of packing into;
5) the concreting sclerosis is linked to be integral body with structure, and the anchor of deactivating loosens and reclaims tension reinforcing steel bar, and structure is applied pretension.
Above-mentioned steps 1) may further comprise the steps in:
1) kind and the ground tackle of selection tension reinforcing steel bar are determined the pre-applied force size P of depression bar and lacing wire, the elastic modulus E of lacing wire material
l, lacing wire second moment of area I
l, lacing wire section area A
l, lacing wire longitudinal fiber and neutral line distance y
l
2) maximum eccentricity of selection compressive pre-stress reinforcing bar and tension reinforcing steel bar, get maximum eccentricity e by inserting very loose easily cooperation, the equilibrium state of compressive pre-stress reinforcing bar and tension reinforcing steel bar is jumped from straight line and is transformed to little bending when making a power greater than critical force, determines the inner diameter d of depression bar
a=D
l+ 2e, D
lDiameter for lacing wire;
3) select compressive pre-stress reinforcing bar kind, determine the elastic modulus E of depression bar material
a, depression bar second moment of area I
a, depression bar section area A
a, depression bar longitudinal fiber and neutral line distance y
a
4) determine the feature that compressive pre-stress reinforcing bar and tension reinforcing steel bar rod end connect, find the solution not bearing length a of depression bar, lacing wire, calculation combination distortion v by the arc line of deflection of selecting
a, σ
aAnd v
l, σ
l
5) to combined deformation v
a, σ
aAnd v
l, σ
lBe out of shape with stress by admissible value and check, if do not meet the above step of repetition, till conforming to.
Compressive pre-stress reinforcing bar operational phase is in elastic stage, and failure stage is in the surrender stage.
Described prestressing force has friction loss.
Described compressive pre-stress reinforcing bar and concrete bonding adopt that profile is with ribbing, anchor rib etc.
Central compression straight-bar of the present invention is not equilibrium conditions with the straight axis, so compressive pre-stress reinforcing bar length do not limit by the member flexibility, not only adopt big flexibility depression bar, and pressure is greater than critical pressure.
The present invention works in elastic range for guaranteeing member, takes to limit the mode of combined stress, and does not take additional constraint, and therefore special measure is not taked in construction, and stretch-draw, anchoring and installation can be adopted commonsense method.
The balance of depression bar-lacing wire system:
The precompression of prepressed method prestressed reinforcement of the present invention is greater than critical force, and depression bar straight line loss of equilibrium is stable.In case cell walls pushes against the tension reinforcing steel bar that penetrates, force tension reinforcing steel bar crooked together.Tension reinforcing steel bar two ends tension has the trend of replying straight line.Push against the district depression bar be subjected to the counteractive restoring force of tension reinforcing steel bar, the spaning middle section deflection is suppressed, as shown in Figure 1.The lateral displacement of putting the two at end connection equates, pushes against the two amount of deflection difference of district in the centre and equals maximum eccentricity, and in all the other contact zones not, the amount of deflection difference of the two is situated between between the zero-sum maximum eccentricity, and the line of deflection of the two becomes arc.With precompression less than critical force different be, depression bar and lacing wire not only are subjected to axial force, and are subjected to moment of flexure, depression bar-lacing wire system satisfies the differential equation of straight beam line of deflection.The feature that links when depression bar and lacing wire two ends not simultaneously, the line of deflection of arciform balance is asymmetric, can regard as by each half different symmetrical arc line of deflection that connect to connect and form pushing against class mark.Therefore only need half to find the solution to having different arciform equilibrium deflection lines of various symmetries that connect features.
For example, the rectangular coordinate system initial point is located at rod end (the x axle overlaps with rod axis), the line of deflection that depression bar and lacing wire rigidly connect is set up the differential equation, can solve the deflection curve equation that pushes against district's depression bar and lacing wire
The deflection curve equation of contact zone depression bar and lacing wire not
The pre-applied force size of P in the formula---depression bar and lacing wire;
E
a---the modulus of elasticity of depression bar material;
I
a---the second moment of area of depression bar;
E
l---the modulus of elasticity of lacing wire material;
I
l---the second moment of area of lacing wire;
The maximum eccentricity of e---depression bar and lacing wire;
L---from end points to the distance that pushes against class mark;
A---depression bar, lacing wire be bearing length not, is equation k
aTgk
aA+k
lThk
lThe least root of a=0, the scope of least root
The stress equation of depression bar and lacing wire is
M in the formula
a---the moment of flexure on the depression bar cross section;
A
a---the section area of depression bar;
y
a---depression bar longitudinal fiber and neutral line distance;
M
l---the moment of flexure on the lacing wire cross section;
A
l---the section area of lacing wire;
y
l---lacing wire longitudinal fiber and neutral line distance.
As seen the distortion of depression bar and lacing wire, stress are the function of many variables.Though material is a linear elasticity, the relation between arciform equilibrium displacement and the pre-applied force is non-linear, and the flexural deformation of arciform balance and stress are directly proportional with the maximum eccentricity of depression bar and lacing wire.Select argument can make the distortion of depression bar and lacing wire, stress sufficiently little, material is still obeyed Hooke's law.Equation is set up in the stress and the distortion of depression bar and lacing wire, can be found the solution other conditions from known conditions, thereby to the compressive pre-stress reinforcing bar with tension reinforcing steel bar carries out Cross section Design and bearing capacity is checked.
Arciform equilibrium deflection line pushes against section length more than or equal to zero, pushes against the district and is shaped as parabola.Whenever pre-applied force constantly increases, push against after section length reaches the length of half sine wave by zero, may increase an oppositely bow, as shown in Figure 2.Each arc line of deflection all is an arciform balance.Each half arc line of deflection shape of many bow equilibrium deflection lines two ends are relevant with the feature that rod end links, and the hinged arciform equilibrium deflection line of all the other line of deflection shapes and depression bar and lacing wire is identical.The shape of the arc line of deflection that depression bar and lacing wire are hinged: the contact zone depression bar is not that 1/4 sine wave, lacing wire are straightway, pushes against the district and is parabola.
Total potential energy minimum of depression bar and the arciform balance of lacing wire, according to minimum potential energy principal, arciform balance is the stability of depression bar and lacing wire, bend balance is the unstable equilibrium state of depression bar and lacing wire more.There is frictional force in ground during practice of construction, and compressive pre-stress reinforcing bar and tension reinforcing steel bar also have stable many bows balance.
The equilibrium state of two kinds of shapes:
The compressive pre-stress muscle and be through in the middle of tension reinforcing steel bar get in touch by active force, tension reinforcing steel bar in the end to compressive pre-stress muscle effect axial compression, the compressive pre-stress muscle also simultaneously in the end to tension reinforcing steel bar effect axial tension.The two constitutes depression bar-lacing wire system by contact.
Analyze stressing conditions, tension reinforcing steel bar is two ends central tension bars, and the strength of materials is the stressed limit.The compressive pre-stress muscle is two ends central compression bars, and the strength of materials and critical pressure are the stressed limit.And be governing factor to the compressive pre-stress muscle critical pressure of big flexibility depression bar.When pre-applied force during less than critical force, depression bar-lacing wire system keeps rectilinear form.When pre-applied force during greater than critical force, compressive pre-stress muscle unstable failure, depression bar-lacing wire system also destroys simultaneously.
The tension reinforcing steel bar in the middle of if compressive pre-stress muscle flexing inwall is run into, the two has increased the horizontal force contact, and the two contact status changes immediately.Because of the deflection in the same way of laterally conflicting of compressive pre-stress muscle, but the pulling force moment of flexure that the cross section produces after deflection in end reduces amount of deflection in the middle of the tension reinforcing steel bar, and tension reinforcing steel bar becomes stretch bending component, and the strength of materials is the stressed limit.The moment of flexure that compressive pre-stress muscle pressure cross section after deflection produces continues deflection, but keeps out the minimizing amount of deflection by what the conflict tension reinforcing steel bar was subjected to, and the compressive pre-stress muscle becomes bending component, and the strength of materials is the stressed limit.Depression bar after the flexing-lacing wire system is bowed shape, and the equilibrium state of post-buckling is stable, and promptly structure still can be carried after the flexing.As long as intensity satisfies, depression bar and lacing wire material do not destroy, and depression bar-lacing wire system does not destroy yet.
Be guaranteed performance, require depression bar-lacing wire system pulling anchor cable stage to be in the small deformation elastic stage.
Owing to adopted such scheme, the present invention to have following characteristics: the present invention does not have the unstability restriction, and length is big, and the cross section is little, and lateral stressed bending is out of shape slightly during pre-applied force freely, can connect lengthening piecemeal, and stretch-draw, anchoring and installation can be adopted commonsense method.
Description of drawings
Fig. 1 is the structural representation of the arciform balance of depression bar of the present invention and lacing wire.
Fig. 2 is arciform balance of the present invention and the schematic diagrames that bend balances more.
Fig. 3 is the correlation schematic diagram of the required member of prepressed method compressive pre-stress reinforcing bar pressurized before stressed.
The specific embodiment
The present invention is further illustrated below in conjunction with the accompanying drawing illustrated embodiment.
Straight-bars such as compressive pre-stress reinforcing bar and tension reinforcing steel bar employing, length (do not have the restriction of member flexibility) arbitrarily.The design reference step is: 1. select the kind and the ground tackle of tension reinforcing steel bar, determine P, E
l, I
l, A
l, y
l2. select the maximum eccentricity of depression bar and lacing wire, maximum eccentricity e should be as far as possible little, gets e by inserting very loose easily cooperation, and the equilibrium state of depression bar and lacing wire is jumped from straight line and transformed to little curved (see figure 1) when making a power greater than critical force, determines the inner diameter d of depression bar
a=D
l+ 2e, D
lDiameter for lacing wire.3. select compressive pre-stress reinforcing bar kind, determine E
a, I
a, A
a, y
a4. determine the feature that depression bar and lacing wire rod end connect, find the solution a, calculation combination distortion v by the arc line of deflection of selecting
a, σ
aAnd v
l, σ
l5. to combined deformation v
a, σ
aAnd v
l, σ
lBe out of shape with stress by admissible value and check, if do not meet the above step of repetition, till conforming to.
The 1. middle kind of tension reinforcing steel bar and the ground tackle selected of described step generally selects by the product that prestressed reinforcement and prestressing force facility factory can provide, and light face high strength cast iron might customize.Tension reinforcing steel bar in the longer compressive pre-stress reinforcing bar should be selected steel strand, bright steel wire for use; The optional face high strength cast iron of using up of tension reinforcing steel bar in the shorter compressive pre-stress reinforcing bar.Ground tackle is to choose on the prestressed reinforcement basis, generally has supporting pattern.The high flexibility pre-pressing method pre-stress muscle is longer, adopts the bigger single steel strand of disrumpent feelings load at present.Steel tendon can be by solving around circle steel strand outside core wire or steel strand as the ordinary steel twisted wire again with steel wire bundle.The prestressing force of high flexibility pre-pressing method pre-stress muscle has tension reinforcing steel bar and inwall frictional prestress loss, so require tension reinforcing steel bar and compressive pre-stress muscle inwall light face and smooth.
The 3. middle compressive pre-stress reinforcing bar kind of selecting of described step is to select suitable material, diameter and wall thickness by the catalogue of steel pipe's production factory, comprising tolerance value, does not also get rid of special development.The prestressing force of high flexibility pre-pressing method pre-stress muscle has tension reinforcing steel bar and inwall frictional prestress loss, so require tension reinforcing steel bar and compressive pre-stress muscle inwall light face and smooth.The requirement of choosing the compressive pre-stress reinforcing bar is: pulling anchor cable stage stress is in elastic stage, and minimum assurance of amount of deflection constructed; Erection stage stress is in elastic stage, and joint must not ftracture simultaneously; Operational phase stress is in elastic stage; Failure stage stress does not at first reach yield strength before the pressure zone concrete destruction.
The feature that 4. middle depression bar of described step and lacing wire rod end connect answers the situation of pressing lever and the actual contact of lacing wire rod end fixed.Such as steel strand intermediate plate anchor is to rigidly connect, and the bar reinforcement bulb-end anchorage is hinged, the jack etc. of whether connecting in addition.Arc line of deflection is to connect Feature Selection by known depression bar and lacing wire rod end.Depression bar and lacing wire have axial force and lateral force effect simultaneously, and the flexural deformation of rod member is caused jointly by lateral force and axial force.Such a problem is commonly referred to the bending with combined axial and lateral load problem.The suffered power of depression bar and lacing wire is active force each other.The thinking that different arc lines of deflection are derived all is: find out depression bar and the lacing wire moment of flexure expression formula on any cross section that is caused by vertical, horizontal power under the minor bending shape, by integral of a differential equation to the bar line of deflection, and utilize the connection feature of different depression bars and lacing wire rod end to determine constant undetermined in the deflection curve equation, can obtain the expression formula of different arc lines of deflection.
The stress limit value of pulling anchor cable stage unit construction distortion is an elastic properties of materials stage permissible stress.Pulling anchor cable stage distortion limit value is prerequisite with the normal running.For preventing to become large deformation problem, need to limit the maximum eccentricity e of depression bar and lacing wire by the Calculation of Deflection moment of flexure.In addition, pulling anchor cable stage member amount of deflection is interim, as long as construction allows and needn't strict control, presses the linear fixed component of design during installation.
The compressive pre-stress reinforcing bar is imbedded concrete structure, should guarantee that also installation, operational phase member are in elastic stage.The failure stage member is in the surrender stage.
The dry joint form (dry joint of prestressed member is caused to compressive stress by the interfacial of the prestressed reinforcement stretch-draw generation of series connection member) of prestressed member is adopted in the compressive pre-stress bar splice.
Tensile stress must not appear in the bar splice of erection stage compressive pre-stress.
The centering that connects two vertical round steel pipe of butt of joining in the compressive pre-stress reinforcing bar of lengthening piecemeal, the anchor clamps of steel plate, top suitable v block are fixed below adopting.
Compressive pre-stress reinforcing bar and tension reinforcing steel bar have the district that pushes against of little curved balance, the accrued friction loss of prestressing force.
Tension reinforcing steel bar is penetrated compressive pre-stress reinforcing bar duct,, make its compression, with the work ground tackle tension reinforcing steel bar is anchored at two ends then with itself afterburning pedestal stretch-draw is stretched out as jack tension reinforcing steel bar.With the compressive pre-stress reinforcing bar structure pressure zone of packing into, wait to build hardening of concrete and structure is linked to be integral body, the anchor of deactivating loosens and reclaims tension reinforcing steel bar, and structure is applied pretension.
Compressive pre-stress reinforcing bar and concrete bonding can adopt with ribbing or anchor rib of profile etc.
The present invention also can use in post-stressed slender rod piece.Penetrate prestressed reinforcement stretch-draw, the minor bending shape that leans on the power muscle with eccentric side slightly replaces the balance of the straight line of central compression, just can make the pressure of big flexibility depression bar greater than critical force, and obvious press-bending does not take place, thus increase flexibility, reduce rigidity, increase axial compression, become the strength problem of combined deformation.
Embodiment:
As shown in Figure 3, alloy structure pipe 5 is steel pipes that the compressive pre-stress reinforcing bar adopts, its role is to constitute prepressed method compressive pre-stress reinforcing bar with the quantity more than one, its center penetrates steel strand 6 (being tension reinforcing steel bar) and uses the jack tension anchoring, the structure of packing into pressure zone fuses, and withdraws from steel strand structure is applied pretension.
Tension reinforcing steel bar is fixed, selects the compressive pre-stress reinforcing bar.Tension reinforcing steel bar adopts the 7 strands of steel strand 6 and the corresponding ground tackle (intermediate plate 1, anchor ring 2) of 270K level, and steel strand 6 encase a bigger core wire by 6 peripheral steel wire spiralitys, least limit intensity 270ksi (1862N/mm
2), nominal diameter 0.6in (15.24mm), stretching control force P
k=1862 * 0.75 * 140=195510N temporarily ignores loss of prestress.
The steel pipe of φ 32 * 8mm specification is selected in the examination of compressive pre-stress reinforcing bar, so determined variable P, the E of distortion and stress formula
l, I
l, A
l, y
l, E
a, I
a, A
a, y
a, e, its Elastic Modulus is the elastic constants of material.Then amount of deflection, the stress to prestressed reinforcement calculates.
Tension reinforcing steel bar shown in Figure 3 is a rigid joint at the node that the steel tube end part anchoring connects.Ask equation k
aTgk
aA+k
lThk
lThe least root of a=0 gets a=395.7mm.If the long L=10000mm of reinforcing bar, from end points to push against class mark apart from l=5000mm, substitution pushes against the deflection curve equation of distinguishing depression bar and lacing wire, then arciform balance maximum defluxion: v
a(l)=and 90.2mm, v
l(l)=89.8mm.Although v
a(l) increase progressively with l, but the lateral deformation of every 10m sections is no more than v
a(l)-v
a(l-5m)=0.0903m.
The 0.09m amount of deflection is unremarkable in the 10m bar, does not also influence the jack operation.During many bow balances in the bar not bearing length equal 1/4 sinusoidal wavelength:
Because push against the sinusoidal wavelength 708.4mm=2 * 354.2mm in section length L-2a=9208.6mm＞1/2 during this routine arciform balance, many bow balances can appear in depression bar and lacing wire.The maximum immunity value of many bow balances reduces.And owing to reasons such as ground friction and resistances, actural deflection is littler than calculated value.
Pushing against district's line of deflection is parabola, and the moment of flexure of depression bar and lacing wire is a constant.In the bar not contact zone line of deflection (sine wave) summit depression bar maximal bending moment M appears
a=74293.8Nmm, this cross section of depression bar is a dangerouse cross-section.The maximum deflection normal stress that depression bar is corresponding with maximal bending moment in this cross section
The compression normal stress corresponding with axle power
Normal stress σ at the dangerous spot place
a=299.5～348.7MPa.
For satisfying the stress limit value 0≤σ of compressive pre-stress reinforcing bar at pulling anchor cable stage
a≤ [σ] will select permissible stress [the σ] 〉=348.7MPa of material.
As seen for the tension reinforcing steel bar of 7 strands of steel strand of 270 grades of 0.6in, select the steel pipe of specification φ 32 * 8mm permissible stress [σ] 〉=348.7MPa to satisfy the stretch-draw requirement.
If make the straight steel pipe that waits of long 10m specification φ 32 * 8mm, under 7 bursts of steel strand effects of 0.6in of the firm knot in two ends, keep straight line balance and stability, its critical force P
Cr=1224.371N " stretching control force P
k=195510N (during long 20m, P
Cr=306.0927N; During long 30m, P
Cr=136.0412N.)。Strut buckling when stretching force reaches critical force does not have restoring force if do not limit the amount of deflection depression bar, though perhaps restricted stress has reached ductility limit, pressure increases to some extent again, and this steel pipe surrender will occur and cause destroying.
The above-mentioned description to embodiment is can understand and apply the invention for ease of those skilled in the art.The person skilled in the art obviously can easily make various modifications to these embodiment, and needn't pass through performing creative labour being applied in the General Principle of this explanation among other embodiment.Therefore, the invention is not restricted to the embodiment here, those skilled in the art should be within protection scope of the present invention for improvement and modification that the present invention makes according to announcement of the present invention.
Claims (12)
1, a kind of prepressed method prestressed reinforcement is characterized in that: it is equilibrium conditions that pulling anchor cable stage compressive pre-stress reinforcing bar and tension reinforcing steel bar lean on the eccentric slightly little curved state of tension reinforcing steel bar with linear state forfeiture back compressive pre-stress reinforcing bar inwall side without acceptance of persons.
2, prepressed method prestressed reinforcement as claimed in claim 1 is characterized in that: pressure is greater than the critical force of big flexibility compressive pre-stress reinforcing bar, and deformation of member form is the combination of axial compression/stretching and pure bending.
3, prepressed method prestressed reinforcement as claimed in claim 1 is characterized in that: for inserting very loose easily matched in clearance, leave certain interval between the two between compressive pre-stress reinforcing bar and the tension reinforcing steel bar.
4, prepressed method prestressed reinforcement as claimed in claim 1 is characterized in that: straight-bars such as described compressive pre-stress reinforcing bar and tension reinforcing steel bar employing.
5, prepressed method prestressed reinforcement as claimed in claim 4 is characterized in that: described compressive pre-stress reinforcing bar adopts steel pipe, and tension reinforcing steel bar adopts steel strand.
6, as claim 1,4 or 5 described prepressed method prestressed reinforcements, it is characterized in that: the joint of described compressive pre-stress reinforcing bar adopts the dry joint form of prestressed member.
7, prepressed method prestressed reinforcement as claimed in claim 1, it is characterized in that: the member pulling anchor cable stage is in the small deformation elastic stage, and erection stage is in elastic stage while joint and must not ftractures.
8, prepressed method prestressed reinforcement as claimed in claim 6 is characterized in that: the centering of two vertical round steel pipe of butt during described compressive pre-stress bar splice, the anchor clamps of steel plate, top suitable v block are fixed below adopting.
9, a kind of implementation method of prepressed method prestressed reinforcement as claimed in claim 1, it is characterized in that: it may further comprise the steps:
1) selected each parameter value that calculates tension reinforcing steel bar and compressive pre-stress reinforcing bar that reaches;
2) tension reinforcing steel bar penetrates compressive pre-stress reinforcing bar duct;
3) tension reinforcing steel bar that stretches out as the stretch-draw of the afterburning pedestal centering of jack of compressive pre-stress reinforcing bar;
4) with the work ground tackle tension reinforcing steel bar is anchored at two ends, with the compressive pre-stress reinforcing bar structure pressure zone of packing into;
5) the concreting sclerosis is linked to be integral body with structure, and the anchor of deactivating loosens and reclaims tension reinforcing steel bar, and structure is applied pretension.
10, the implementation method of prepressed method prestressed reinforcement as claimed in claim 9 is characterized in that: may further comprise the steps above-mentioned steps 1):
1) kind and the ground tackle of selection tension reinforcing steel bar are determined the pre-applied force size P of depression bar and lacing wire, the elastic modulus E of lacing wire material
l, lacing wire second moment of area I
l, lacing wire section area A
l, lacing wire longitudinal fiber and neutral line distance y
l
2) maximum eccentricity of selection compressive pre-stress reinforcing bar and tension reinforcing steel bar, get maximum eccentricity e by inserting very loose easily cooperation, the equilibrium state of compressive pre-stress reinforcing bar and tension reinforcing steel bar is jumped from straight line and is transformed to little bending when making a power greater than critical force, determines the inner diameter d of depression bar
a=D
l+ 2e, D
lDiameter for lacing wire;
3) select compressive pre-stress reinforcing bar kind, determine the elastic modulus E of depression bar material
a, depression bar second moment of area I
a, depression bar section area A
a, depression bar longitudinal fiber and neutral line distance y
a
4) determine the feature that compressive pre-stress reinforcing bar and tension reinforcing steel bar rod end connect, find the solution not bearing length a of depression bar, lacing wire, calculation combination distortion v by the arc line of deflection of selecting
a, σ
aAnd v
l, σ
l
5) to combined deformation v
a, σ
aAnd v
l, σ
lCheck by admissible value, if do not meet the above step of repetition, till conforming to.
11, the implementation method of prepressed method prestressed reinforcement as claimed in claim 9 is characterized in that: compressive pre-stress reinforcing bar operational phase is in elastic stage, and failure stage is in the surrender stage.
12. the implementation method of prepressed method prestressed reinforcement as claimed in claim 9 is characterized in that: described compressive pre-stress reinforcing bar and concrete bonding adopt with ribbing, the anchor rib of profile.
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| CN200910054610A Pending CN101614053A (en) | 2009-07-10 | 2009-07-10 | High flexibility pre-pressing method pre-stress steel bar and its implementation |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103792139A (en) * | 2012-10-29 | 2014-05-14 | 同济大学 | Method for measuring flexural rigidity of immersed tube tunnel joint |
| CN106096233A (en) * | 2016-05-31 | 2016-11-09 | 中国航空工业集团公司西安飞机设计研究所 | A kind of cable wire Calculation Method of Deflection by uniform Lateral Force |
| CN107255539A (en) * | 2017-06-15 | 2017-10-17 | 深圳大学 | A kind of rust test specimen stress calibrating installation and answer force calibration method |
| CN108549766A (en) * | 2018-04-12 | 2018-09-18 | 佛山金皇宇机械实业有限公司 | Interference fit pressurization method for aluminum profile corner forming |
| CN110334481A (en) * | 2019-07-30 | 2019-10-15 | 中国航发沈阳发动机研究所 | A kind of cold test device damping screen twine calculation method for stress |
| CN113567242A (en) * | 2021-07-05 | 2021-10-29 | 交通运输部公路科学研究所 | Method for detecting resistance of reinforced concrete or prestressed concrete beam |
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2009
- 2009-07-10 CN CN200910054610A patent/CN101614053A/en active Pending
Non-Patent Citations (1)
| Title |
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| 刘猛: "先压法双预应力混凝土梁的静载性能研究", 《中国优秀硕士学位论文全文数据库工程科技Ⅱ辑》 * |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103792139A (en) * | 2012-10-29 | 2014-05-14 | 同济大学 | Method for measuring flexural rigidity of immersed tube tunnel joint |
| CN103792139B (en) * | 2012-10-29 | 2016-01-20 | 同济大学 | A kind of measuring method of Joints in Immersed Tunnel bendind rigidity |
| CN106096233A (en) * | 2016-05-31 | 2016-11-09 | 中国航空工业集团公司西安飞机设计研究所 | A kind of cable wire Calculation Method of Deflection by uniform Lateral Force |
| CN107255539A (en) * | 2017-06-15 | 2017-10-17 | 深圳大学 | A kind of rust test specimen stress calibrating installation and answer force calibration method |
| CN108549766A (en) * | 2018-04-12 | 2018-09-18 | 佛山金皇宇机械实业有限公司 | Interference fit pressurization method for aluminum profile corner forming |
| CN108549766B (en) * | 2018-04-12 | 2021-11-16 | 佛山金皇宇机械实业有限公司 | Interference fit pressurization method for aluminum profile corner forming |
| CN110334481A (en) * | 2019-07-30 | 2019-10-15 | 中国航发沈阳发动机研究所 | A kind of cold test device damping screen twine calculation method for stress |
| CN113567242A (en) * | 2021-07-05 | 2021-10-29 | 交通运输部公路科学研究所 | Method for detecting resistance of reinforced concrete or prestressed concrete beam |
| CN113567242B (en) * | 2021-07-05 | 2022-02-18 | 交通运输部公路科学研究所 | Method for detecting resistance of reinforced concrete or prestressed concrete beam |
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Application publication date: 20091230 |