CN101710011B - Method for testing and monitoring cable force of PC steel strand stay cable - Google Patents

Abstract

The invention discloses a method for testing the cable force of a PC steel strand stay cable, which is used for testing steel strands individually stretched by the equal tension method. The method comprises the following steps of: obtaining the actual effective tension force of each steel strand based on the actual extension amount and the actual anchorage tension force before anchoring the steel strands; obtaining the linear regression equation of the steel strands according to the actual tension sequence number and the actual effective tension force of the steel strands; obtaining the effective tension force representative value of each anchored steel strand; and multiplying the effective tension representative value of the last stretched steel strand by the number of the steel strands to obtain the cable force of the stay cable.

Description

The rope force test method of PC steel strand stay cable

Technical field

The present invention relates to the Suo Li stretch-draw method of testing of cable-stayed bridge suspension cable, be specifically related to the rope force test method of PC steel strand stay cable.

Background technology

Cable-stayed bridge is bigger than the span ability of beam bridge, is the main bridge type of Longspan Bridge.The superstructure of cable-stayed bridge mainly is made up of Sarasota, suspension cable and girder three parts; Its principal feature is to utilize Sarasota to draw suspension cable suspention girder to cross over; Wherein, Suspension cable is one of topmost force structure of cable-stayed bridge, generally adopts two kinds of forms of high strength parallel wire stay and PC guy of twisted steel cable.

The high strength parallel wire stay is generally plant-manufactured finished product rope, a whole at the construction field (site) installation, and adopt large-tonnage crowd anchor system to carry out stretch-draw anchor, and its Installation And Test is comparatively simple, and still along with the increase of drag-line diameter, its installation and transportation have difficulties.The PC steel strand stay cable is then comparatively flexible, is made up of the many antiseptic finished steel twisted wires of process, need at the construction field (site) through processing, by root install, by many operations such as root stretch-draw and anchoring, tight ropes.

Need test stay cable force in the Construction of Cable-Stayed Bridges, common inclined cable force test method mainly contains tensimeter measurement method, magnetic flux measures method, pressure transducer measurement method and vibration frequency and measures four kinds of methods.The be stressed restriction of oil meter precision of tensimeter measurement method can not reflect the actual Suo Li after the anchor-hold loss simultaneously, generally only is applicable to stretching construction; The magnetic flux method that measures is measured through the variation of magnetic flux in the mensuration rope and is drawn cable force and temperature, domestic less application; Pressure transducer measures method can effectively measure the effective value that draws cable force in the work progress, is applicable to high strength parallel wire stay and PC guy of twisted steel cable; Vibration frequency measurement method is confirmed Suo Li according to the relation of the natural frequency of vibration and Suo Li then through the natural frequency of vibration of test suspension cable, and high strength parallel wire stay and PC guy of twisted steel cable all are suitable for.

The PC guy of twisted steel cable generally adopts the isostension method to pursue the root stretching construction; Its principle is that the influence of the tension of steel strand stretch-draw accomplished according to the Sarasota that is caused by the steel strand wires of post-stretching and the relative displacement between the girder surpasses the stretch-draw corrected Calculation to the steel twisted-line tension-force of pretensioning; And with the stretching control force of revised stretching force as steel strand wires; Change by the reading that is installed in first pressure transducer on the steel strand wires in the stretching process and come the assist control stretching force, thereby reach the purpose that whole bundle inclined guy cable stretching is accomplished each root tension of steel strand unanimity of back.Because the isostension method can't be considered in the stretching process in the variation of steel strand wires sag, concrete shrinkage and creep, the stretching process factors such as system temperature variation; Also receive the actual rigidity of Sarasota, girder and suspension cable simultaneously and theoretical value is inconsistent influences, thereby can cause each the root steel strand wires Suo Li of suspension cable after stretch-draw is accomplished to have unevenness to a certain degree.Meanwhile; For the cable-stayed bridge that adopts the balanced cantilever construction method; The full-bridge Suo Li adjustment that possibly carry out of Cheng Qiaohou for ease generally can be put into into PC guy of twisted steel cable " tight rope " operation after the bridge, thereby can the Suo Li test of PC guy of twisted steel cable in the work progress be impacted.According to existing method of testing; If adopts pressure sensor measurement method is carried out the Suo Li test; Causing finding out representative steel strand wires owing to each root steel strand wires Suo Li is inhomogeneous tests; Then must test all steel strand wires; Its workload is huge, and cost is higher and consuming time more; If adopt frequency measurement method to test, because the not tight rope of PC guy of twisted steel cable, must there be error in the drag-line natural frequency of vibration of then testing gained.Therefore, only the stay cable force of PC guy of twisted steel cable Construction of Cable-Stayed Bridges is tested and had difficulties through existing method of testing.

Summary of the invention

Technical matters to be solved by this invention is to solve existing method of testing the stay cable force of PC guy of twisted steel cable Construction of Cable-Stayed Bridges is tested the problem that has difficulties.

In order to solve the problems of the technologies described above, the technical scheme that the present invention adopted provides a kind of rope force test method of PC steel strand stay cable, may further comprise the steps:

S10, employing isostension method are by every steel strand wires in the root stretch-draw suspension cable;

S20, according to the actual elongation Δ L before the steel strand wires anchoring _BaiWith actual anchoring stretching force N _AiObtain the actual effective pull N of every steel strand wires _Ei

S30, with the actual stretching sequence number i and the actual effective pull N of every steel strand wires _EiCarry out linear regression analysis, and obtain the equation of linear regression formula according to least square method;

S40, with the said equation of linear regression formula of actual stretching sequence number i substitution, obtain the effective stretching force typical value N after the every steel strand wires anchoring _Ri

The effective pull typical value N of S50, steel strand wires that last root stretch-draw is accomplished _RnMultiply by the Suo Li that steel strand wires quantity that this suspension cable comprises obtains this suspension cable;

I is the actual stretching sequence number of steel strand wires, i=1,2,3 ..., n, n is the quantity of steel strand wires in the suspension cable.

In the rope force test method of above-mentioned PC steel strand stay cable, the actual elongation Δ L of steel strand wires _BaiObtain through following steps:

S101, the elongation Δ L with steel strand tension during to 100% stretching control force _100iWith the elongation Δ L of stretch-draw to the D% stretching control force _DiSubtract each other, try to achieve the steel strand wires nominal elongation Δ L that comprises the sag influence under (100-D) % stretching control force _{(100-D) i}, D%=10%～15% wherein;

S102, calculate under the 100% stretching control force state and the stress-less length S of steel strand wires under the D% stretching control force state through the catenary formula _100iAnd S _Di, and obtain its difference DELTA S _{(100-D) i}

Nominal elongation Δ L under S103, usefulness (100-D) the % stretching control force state _{(100-D) i}Deduct the difference DELTA S of said stress-less length _{(100-D) i}Obtain revising elongation Δ L _{(100-D) i}';

S104, will revise elongation Δ L _{(100-D) i}' be scaled to 100%, be the actual elongation Δ L of steel strand wires under 100% stretching control force _i

S105, the elongation Δ L when steel strand tension is arrived the anchoring stretching force _AiElongation Δ L with stretch-draw during to 100% stretching control force _100iSubtract each other, again with 100% stretching control force under actual elongation Δ L _iAddition is the preceding actual elongation Δ L of steel strand wires anchoring _Bai

Among the step S101, D=10 or 15.

The actual effective pull N of steel strand wires _EiObtain through following steps:

S110, the lifting jack oil pressure meter reading when passing through steel strand tension to anchoring stretching force obtain the actual anchoring stretching force value N of every steel strand wires _Ai

S111, the elongation Δ L when steel strand tension is arrived the anchoring stretching force _AiWith the elongation Δ L after the anchoring _AaiSubtract each other the elongation loss δ that causes owing to factors such as intermediate plate retractions when obtaining the steel strand wires anchoring _i

S112, with the actual elongation Δ L before the steel strand wires anchoring _BaiDeduct elongation loss δ _iAfter, again divided by the actual elongation Δ L before the anchoring _Bai, then with actual anchoring stretching force N _AiMultiply each other, obtain the actual effectively stretching force value N after the every steel strand wires anchoring _Ei

The present invention has following advantage:

1, on the basis of the method for utilization linear regression analysis rationally, sets up method, efficiently solve the problem that only can't carry out system evaluation to the Suo Li state after the PC steel strand stay cable stretch-draw completion through existing method of testing to the evaluation of PC steel strand stay cable tensile state.

2, to the Suo Li test problem of suspension cable in the follow-up work progress of cable-stayed bridge that adopts the linear regression analysis method to carry out the Suo Li evaluation complete solution has been proposed.

3, especially a kind of effective solution has been proposed for the Suo Li test problem of suspension cable in Construction of Cable-Stayed Bridges of just accomplishing " tight rope " operation at Cheng Qiaohou.

4, construction is convenient in strong points, economical rationality.

Description of drawings

Fig. 1 is the structural arrangement form of the embodiment of the invention.

Fig. 2 is the suspension cable section form of the embodiment of the invention.

Fig. 3 is a PC steel strand stay cable Suo Li test flow chart.

Fig. 4 is the steel strand tension data drawing list.

Fig. 5 is a steel strand wires anchoring elongation loss calculation chart.

Fig. 6 is forward and backward effective stretching force and a typical value thereof of steel strand wires anchoring.

Fig. 7 is the corresponding effective stretching force of steel strand wires and the deviate and the deviation percent of typical value;

Label and corresponding title thereof are following among the figure: the 1-girder; The 2-Sarasota; The 3-PC steel strand stay cable; The 4-PC steel strand wires; The elongation Δ L of 5a-stretch-draw to 10% or 15% stretching control force ₁₅The elongation Δ L of 5b-steel strand tension during to 100% stretching control force ₁₀₀The steel strand wires nominal elongation Δ L that comprises the sag influence under 5c-90% or 85% stretching control force ₈₅The actual elongation Δ L of 5d-steel strand wires under 100% stretching control force; Elongation Δ L when the 5e-steel strand tension arrives the anchoring stretching force _aElongation Δ L after the anchoring of 5f-steel strand wires _AaThe elongation loss δ that causes by factors such as intermediate plate retractions during the 5g-anchoring; The actual anchoring stretching force value N of 6a-steel strand wires _AiActual effectively stretching force value N after the anchoring of 6b-steel strand wires _EiEffective stretching force typical value N after the anchoring of 6c-steel strand wires _RiThe effective stretching force that the 6d-steel strand wires are corresponding and the deviate of typical value; The effective stretching force that the 6e-steel strand wires are corresponding and the deviation percent of typical value.

Embodiment

Below in conjunction with specific embodiment and accompanying drawing the present invention is carried out detailed explanation, this embodiment is a multispan continuous box girder low-pylon cable-stayed bridge, and is as depicted in figs. 1 and 2; Girder 1 is reinforced concrete structure with Sarasota 2; Be furnished with 6 pairs of PC steel strand stay cables 3 on each Sarasota 2, every pair of suspension cable respectively is made up of the high strength low relaxed steel strand wires 4 of 91 φ 15.24, and the two ends of steel strand stay cable 3 are anchored at respectively on the girder of girder 1 and Sarasota 2; Cat head place at Sarasota 2 is provided with steering gear; " tight rope " operation of steel strand wires 4 is carried out after Cheng Qiao, adopts the stretch-draw of isostension method, and stretching construction carries out at two ends simultaneously.

The rope force test method of PC steel strand stay cable provided by the invention may further comprise the steps, and is as shown in Figure 3:

S10, employing isostension method are by the every steel strand wires 4 in the current suspension cable 3 of root stretch-draw;

S20, according to the actual elongation Δ L before the steel strand wires anchoring after the stretch-draw _BaWith actual anchoring stretching force N _aObtain the actual effective pull N of every steel strand wires _e

S30, with the actual stretching sequence number and the actual effective pull N of steel strand wires _eCarry out linear regression analysis, and obtain the equation of linear regression formula of steel strand wires according to least square method;

S40, with the said equation of linear regression formula of actual stretching sequence number substitution, obtain the effective stretching force typical value N after the every steel strand wires anchoring _r

The effective pull typical value N of S50, steel strand wires that last root stretch-draw is accomplished _rMultiply by the Suo Li that steel strand wires quantity that this suspension cable comprises obtains this suspension cable.

In the said method, the actual elongation Δ L of every steel strand wires _iObtain through following steps, i is the actual stretching sequence number of steel strand wires, i=1,2,3 ..., n, n is the quantity of steel strand wires in the suspension cable, is that example is explained with steel strand wires wherein below, all the other steel strand wires therewith roughly the same:

S101, the elongation Δ L with steel strand tension during to 100% stretching control force ₁₀₀Elongation Δ L with stretch-draw to 10% or 15% stretching control force ₁₀Or Δ L ₁₅Subtract each other, obtain comprising under 90% or 85% stretching control force steel strand wires nominal elongation Δ L of sag influence ₉₀With Δ L ₈₅,

That is:

ΔL ₉₀＝ΔL ₁₀₀-ΔL ₁₀；

ΔL ₈₅＝ΔL ₁₀₀-ΔL ₁₅。

S102, the length of unstressed cable computing formula through catenary, the 100% stretching control force state that calculates respectively down with 10% or 15% stretching control force state under the stress-less length S of steel strand wires ₁₀₀And S ₁₀Or S ₁₅, and obtain its difference DELTA S _100-10Or Δ S _100-15,

That is: the length of unstressed cable L=S-Δ S of catenary

In the formula: S is that the stress rope of catenary is long, and its formula is:

$S={\&Integral;}_0^{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="H2009102598540E00011.png"\; state="\{\{state\}\}">l</figure-callout>}}\sqrt{1+{\left(\frac{\mathrm{dy}}{\mathrm{dx}}\right)}^2}\mathrm{dx}=-\frac{H}{q}[\mathrm{sh}(-\frac{q}{H}l+\frac{q}{H}t)-\mathrm{sh}\left(\frac{q}{H}t\right)],$

Δ S is the long changing value of the rope of catenary, and its formula is:

$\mathrm{\&Delta;S}=\frac{H}{\mathrm{EA}}{\&Integral;}_0^l[1+{\left(\frac{\mathrm{dy}}{\mathrm{dx}}\right)}^2]\mathrm{dx}+\mathrm{\&alpha;\&Delta;t}{\&Integral;}_0^{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="H2009102598540E00011.png"\; state="\{\{state\}\}">l</figure-callout>}}\sqrt{1+{\left(\frac{\mathrm{dy}}{\mathrm{dx}}\right)}^2}\mathrm{dx},$

Parameter among S and the Δ S sees " the linear computing method of suspension cable are inquired into " (2006 steel bridges science and technology forum whole nation academic meeting paper collection, 2006) for details.

ΔS _100-10＝S ₁₀₀-S ₁₀；

ΔS _100-15＝S ₁₀₀-S ₁₅。

S103, utilize the difference DELTA S of stress-less length under the two states _100-10Or Δ S _100-15Nominal elongation Δ L to 90% or 85% stretching control force ₉₀Or Δ L ₈₅Revise and obtain revising elongation Δ L ₉₀' or Δ L ₈₅',

That is:

ΔL ₉₀’＝ΔL ₉₀-ΔS _100-15；

ΔL ₈₅’＝ΔL ₈₅-ΔS _100-15。

S104, will revise elongation Δ L ₉₀' or Δ L ₈₅' be scaled to 100%, be the actual elongation Δ L of steel strand wires under 100% stretching control force,

That is:

Δ L=Δ L ₉₀' * 100/90 or,

ΔL＝ΔL ₈₅’×100/85。

S105, the elongation Δ L when steel strand tension is arrived the anchoring stretching force _aElongation Δ L with stretch-draw during to 100% stretching control force ₁₀₀Subtract each other, again with 100% stretching control force under actual elongation Δ L addition, be the actual elongation Δ L before the steel strand wires anchoring _Ba,

That is:

ΔL _ba＝ΔL _a-ΔL ₁₀₀+ΔL。

Only with the property explanation as an example of 90% or 85% stretching control force, still, this method is not limited to above-mentioned two kinds of situation, can select any value between 90%～85% in the above-mentioned steps.

Stretching control force is the theoretical stretching force of steel strand tension, i.e. desired value, and the anchoring stretching force is the actual stretching force before the steel strand wires anchoring.

Fig. 4 is the steel strand tension data drawing list, this table record be the elongation Δ Ls of steel strand wires 4 stretch-draw to 15% stretching control force ₁₅Elongation Δ L with stretch-draw during to 100% stretching control force ₁₀₀, represent with 5a and 5b respectively.With Δ L ₁₀₀With Δ L ₁₅Subtract each other, can try to achieve the steel strand wires nominal elongation Δ L that comprises the sag influence under 85% stretching control force ₈₅, represent with 5c among the figure; The stress-less length S of these steel strand wires under 100% and 85% stretching control force that calculates respectively through the catenary formula again ₁₀₀And S ₁₅, and calculate its difference DELTA S _100-15The difference of utilizing stress-less length under the two states then is to Δ L ₈₅(being 5c) revises and obtains Δ L ₈₅'; At last with Δ L ₈₅' be scaled to 100%, be the actual elongation Δ L of steel strand wires under 100% stretching control force, represent with 5d among the figure.

The actual effective pull N of single steel strand _eObtain through following steps:

S110, the lifting jack oil pressure meter reading when passing through steel strand tension to anchoring stretching force obtain the actual anchoring stretching force value N of every steel strand wires _Ai(i is the actual stretching sequence number of steel strand wires, i=1,2,3 ..., n, n is the quantity of steel strand wires in the suspension cable).During through the jack tension steel strand wires; There is certain relation in the reading of oil pressure gauge with the stretching force that is applied on the steel strand wires; This relation can draw through test at an easy rate; Therefore can obtain the calibration formula between the stretching force on oil pressure gauge reading and the steel strand wires through experiment, can obtain the actual anchoring stretching force value N of every steel strand wires through this calibration formula _AiBe that example is explained with steel strand wires wherein below, all the other steel strand wires therewith roughly the same.

S111, the elongation Δ L when steel strand tension is arrived the anchoring stretching force _aWith the elongation Δ L after the anchoring _AaSubtract each other, the elongation loss δ that causes owing to factors such as intermediate plate retractions when obtaining the steel strand wires anchoring,

That is:

δ＝ΔL _a-ΔL _aa

S112, with the actual elongation Δ L before the steel strand wires anchoring _BaAfter deducting elongation loss δ, again divided by the actual elongation Δ L before the anchoring _Ba, then with actual anchoring stretching force N _aMultiply each other, obtain the actual effectively stretching force value N after the steel strand wires anchoring _e,

That is:

N _e＝N _a×(ΔL _ba-δ)/ΔL _ba

The detailed description of step S30 is following:

Actual stretching sequence number i with every steel strand wires is the X coordinate, with the actual effective pull N after the anchoring _eFor the Y coordinate carries out linear regression analysis, carry out linear fit by principle of least square method, obtaining with X is that independent variable, Y are once formula, i.e. the equation of linear regression formula of dependent variable.

Y＝a×X+b

Wherein, a, b are constant, and are drawn by linear fit.

The stretching sequence number i of each root steel strand wires as the X variable once formula derived of substitution respectively, is obtained the effective stretching force typical value N after the every steel strand wires anchoring _Ri

Fig. 5 is a steel strand wires anchoring elongation loss calculation chart, and among the figure, 5e representes Δ L _a, 5f representes Δ L _Aa, 5g representes δ.

Fig. 6 is forward and backward effective stretching force and a typical value thereof of steel strand wires anchoring, and 6a representes the actual anchoring stretching force value N of steel strand wires among the figure _Ai, 6b representes the actual effectively stretching force value N after the steel strand wires anchoring _Ei, 6c representes the effective stretching force typical value N after the steel strand wires anchoring _Ri

(1), stay cable force state estimation.

(1) with the actual effective pull value N of each root steel strand wires _EiWith the effective pull typical value N that derives through linear recurrence _RiCompare, can evaluate the tensile state of single steel strand.

Deviate: N _Ei-N _Ri≤[tolerance deviation value]

Deviation percent: (N _Ei-N _Ri)/N _Ri≤[tolerance deviation number percent]

If deviation meets the demands, explain that the tension of steel strand homogeneity is better; If deviation does not meet the demands, explain that the tension of steel strand homogeneity is relatively poor, should adjust the bigger tension of steel strand of deviation according to deviate.

The effective pull typical value N of the steel strand wires of (2) last root stretch-draw being accomplished _RnAs the pulling force typical value of any steel strand wires after the whole skew cables construction completion, the Suo Li typical value T of therefore whole skew cables _rShould equal the effective pull typical value N of last skew cables _RnMultiply by the steel strand wires quantity n that this suspension cable comprises.To put in order the Suo Li typical value T of skew cables at last _rWith theoretical value T _tCompare, can evaluate the Suo Li state of whole skew cables.

Deviate: T _r-T _t≤[tolerance deviation value]

Deviation percent: (T _r-T _t)/T _t≤[tolerance deviation number percent]

If deviation meets the demands, explain that stay cable force can satisfy design and code requirement; If deviation does not meet the demands, explain that the stay cable force deviation is too big, the reply stay cable force is adjusted.The Suo Li adjustment is still undertaken by single steel strand, and then before the Suo Li adjustment, the pulling force numerical value that each root steel strand wires need be adjusted can adopt following formula to calculate:

ΔN _i＝(T _t-T _r)/n+(N _ri-N _ei)

Consider by root stretch-draw steel strand wires and can impact, therefore can control according to the elongation Δ of the required adjustment of each root steel strand wires to other tension of steel strand.Under the less situation of catenary sag, sag can be ignored the influence of catenary arc length, and when therefore tension of steel strand being adjusted on a small quantity, steel strand wires elongation Δ also can be ignored by the influence of sag.

That is:

Δ＝(ΔN _i×S)/(E×A)

In the formula: Δ N _iBe the pulling force numerical value that steel strand wires need be adjusted, S is the length of steel strand wires, and E is the elastic modulus of steel strand wires, and A is the steel strand wires area of section.

(2), Suo Li test in the PC steel strand stay cable work progress.

1, adopts pressure sensor measurement method is carried out the method for Suo Li test

(1) press after the stretch-draw of isostension method accomplishes at whole skew cables, the reading that is installed in the pressure transducer on the steel strand wires carried out record, with it as pulling force initial value N ₀

(2) the arbitrary operating mode after inclined guy cable stretching is accomplished is tested the steel strand wires that pressure transducer is installed, with the value of thrust N of these steel strand wires under this operating mode of instrument test gained _jPulling force initial value N when accomplishing with stretch-draw ₀Compare, can try to achieve the tension variations value Δ N of single steel strand.The tension variations value Δ N of single steel strand multiply by the Suo Li changing value Δ T that steel strand wires quantity n that this suspension cable comprises can obtain this suspension cable.

Suo Li typical value T when Suo Li changing value Δ T and the inclined guy cable stretching that (3) will test gained accomplished _rAddition is the actual Suo Li T of suspension cable in this operating mode _Rj, again with theoretical value T _TjCompare.

2, adopt vibration frequency measurement method to carry out the method one of Suo Li test

(1) the whole skew cables after the stretch-draw completion is tested, write down its natural frequency of vibration F ₀As initial value.

(2) according to the approximation relation between the stay cable force and the natural frequency of vibration, T=KF ²(wherein, T is Suo Li, and K is a proportionality constant, and F is the single order natural frequency of vibration of drag-line or claims fundamental frequency) is with the Suo Li typical value T after the inclined guy cable stretching completion _rWith natural frequency of vibration initial value F ₀Can try to achieve proportionality constant K after the substitution ₀Value.

(3) the arbitrary operating mode after inclined guy cable stretching is accomplished is tested suspension cable, with the natural frequency of vibration F of instrument test gained _jWith proportionality constant K ₀Value substitution relation formula, T=KF ², can try to achieve the suspension cable nominal Suo Li T under this operating mode _RjThen with T _RjWith theoretical value T _TjCompare.

3, adopt vibration frequency measurement method to carry out the method two of Suo Li test

(1) the whole skew cables after the stretch-draw completion is tested, write down its natural frequency of vibration F ₀As initial value.

(2) this suspension cable of arbitrary operating mode after inclined guy cable stretching is accomplished is tested, with the natural frequency of vibration F of instrument test gained _jCarry out record.

(3) confirm the Suo Li changing value:

Freely-supported string tension formula according to consideration drag-line rigidity:

T＝4mL ²F _k ²/k ²-EI?k ²π ²/L ²

In the formula: T is Suo Li, and m is the line mass of suspension cable, and L is a computational length, F _kBe the k order frequency, k is the frequency exponent number, and EI is the drag-line bendind rigidity.

If adopt the frequency that is all the k rank, the Suo Li changing value of the drag-line stiffness effect that then can be eliminated is:

ΔT _j＝4mL ²F _jk ²/k ²-4mL ²F _0k ²/k ²＝4mL ²/k ²(F _jk ²-F _0k ²)

In the formula: F _JkBe the k order frequency of any working condition measurement gained, F _0kK order frequency for test gained after the whole skew cables stretch-draw completion.

(4) will calculate the Suo Li changing value Δ T of gained _jSuo Li typical value T when accomplishing with inclined guy cable stretching _rAddition is the actual Suo Li T of suspension cable in this operating mode _Rj, again with theoretical value T _TjCompare.

Fig. 7 is the corresponding effective stretching force of steel strand wires and the deviate and the deviation percent of typical value.Actual effective pull value N with each root steel strand wires _Ei6b and the effective pull typical value N that derives through linear recurrence _Ri6c subtracts each other can obtain deviate 6d; With deviate 6d and effective pull typical value N _Ri6c compares and can obtain deviation percent 6e.Tolerance deviation through with deviate 6d and deviation percent 6e and related specifications compares, and can evaluate the tensile state of single steel strand.

If the tensile state of single steel strand meets the demands, then with the effective pull typical value N of last skew cables _RnMultiply by the steel strand wires quantity n that this suspension cable comprises, can obtain the Suo Li typical value T of whole skew cables _r, at last to putting in order the Suo Li typical value T of skew cables _rWith theoretical value T _tCarry out deviate and deviation percent analysis, and compare, can evaluate the Suo Li state of whole skew cables with the tolerance deviation of related specifications.

If the situation that whole skew cables Suo Li deviation transfinites occurs, can be with (T _t-T _r)/n and deviate 6d converse the elongation of the required adjustment of each root steel strand wires as the foundation of each root tension of steel strand adjustment, instruct with this and transfer the rope construction.

Inclined guy cable stretching is accomplished also after design and code requirement are satisfied in test; Can carry out the subsequent handling construction; But supplementary meanss such as adopts pressure sensor measurement method, vibration frequency measurement method are carried out tracking and testing to the stay cable force in the work progress in the work progress, to reach the purpose of stay cable force being monitored in the CONSTRUCTION OF CABLE-STAYED BRIDGE overall process.

The present invention is through the employing of above measure, efficiently solves in the PC steel strand stay cable stretch-draw work problem of Suo Li being carried out system evaluation, and proposed complete solution for the Suo Li test problem in the follow-up work progress of cable-stayed bridge.

The present invention is not limited to above-mentioned preferred forms, and anyone should learn the structural change of under enlightenment of the present invention, making, and every have identical or close technical scheme with the present invention, all falls within protection scope of the present invention.

Claims (3)

1.PC the rope force test method of steel strand stay cable is characterized in that may further comprise the steps:

S10, employing isostension method are by every steel strand wires in the root stretch-draw suspension cable;

S20, according to the actual elongation Δ L before the steel strand wires anchoring _BaiWith actual anchoring stretching force N _AiObtain the actual effective pull N of every steel strand wires _Ei

S30, with the actual stretching sequence number i and the actual effective pull N of every steel strand wires _EiCarry out linear regression analysis, and obtain the equation of linear regression formula according to least square method;

S40, with the said equation of linear regression formula of actual stretching sequence number i substitution, obtain the effective stretching force typical value N after the every steel strand wires anchoring _Ri

The effective pull typical value N of S50, steel strand wires that last root stretch-draw is accomplished _RnMultiply by the Suo Li that steel strand wires quantity that this suspension cable comprises obtains this suspension cable;

I is the actual stretching sequence number of steel strand wires, i=1,2,3 ..., n, n is the quantity of steel strand wires in the suspension cable;

Wherein, the actual elongation Δ L of steel strand wires _BaiObtain through following steps:

S101, the elongation Δ L with steel strand tension during to 100% stretching control force _100iWith the elongation Δ L of stretch-draw to the D% stretching control force _DiSubtract each other, try to achieve the steel strand wires nominal elongation Δ L that comprises the sag influence under (100-D) % stretching control force _{(100-D) i}, D%=10%～15% wherein;

S102, calculate under the 100% stretching control force state and the stress-less length S of steel strand wires under the D% stretching control force state through the catenary formula _100iAnd S _Di, and obtain its difference DELTA S _{(100-D) i}

Nominal elongation Δ L under S103, usefulness (100-D) the % stretching control force state _{(100-D) i}Deduct the difference DELTA S of said stress-less length _{(100-D) i}Obtain revising elongation Δ L _{(100-D) i}';

S104, will revise elongation Δ L _{(100-D) i}' be scaled to 100%, be the actual elongation Δ L of steel strand wires under 100% stretching control force _i

S105, the elongation Δ L when steel strand tension is arrived the anchoring stretching force _AiElongation Δ L with stretch-draw during to 100% stretching control force _100iSubtract each other, again with 100% stretching control force under actual elongation Δ L _iAddition is the preceding actual elongation Δ L of steel strand wires anchoring _Bai

2. the rope force test method of PC steel strand stay cable as claimed in claim 1 is characterized in that, among the step S101, and D=10 or 15.

3. the rope force test method of PC steel strand stay cable as claimed in claim 2 is characterized in that, the actual effective pull N of steel strand wires _EiObtain through following steps:

S110, the lifting jack oil pressure meter reading when passing through steel strand tension to anchoring stretching force obtain the actual anchoring stretching force value N of every steel strand wires _Ai

S111, the elongation Δ L when steel strand tension is arrived the anchoring stretching force _AiWith the elongation Δ L after the anchoring _AaiSubtract each other, the elongation that causes loses δ because intermediate plate bounces back when obtaining the steel strand wires anchoring _i

S112, with the actual elongation Δ L before the steel strand wires anchoring _BaiDeduct elongation loss δ _iAfter, again divided by the actual elongation Δ L before the anchoring _Bai, then with actual anchoring stretching force N _AiMultiply each other, obtain the actual effectively stretching force value N after the every steel strand wires anchoring _Ei

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