CN105158300A - Detection method for bridge linear steel member - Google Patents

Abstract

The invention provides a detection method for a bridge linear steel member, which can be used for detecting the prestress of a detected linear steel member. The detection method for the bridge linear steel member comprises the following steps: calculating the resistance value scope of a detected linear steel member according to parameters of the detected linear steel member; determining a wire needing to be connected according to the calculated resistance value scope of the detected linear steel member; determining the positions of two ends of the detected linear steel member and respectively and correspondingly connecting two connecting pieces and two wires to the detected linear steel member and a precise resistance tester; selecting the test gear of the precise resistance tester to start measurement. According to the detection method, the resistance value of a detected member is evaluated first, and then the test result can be analyzed by utilizing the actual resistance value of the connecting pieces and a wire test member by using the precise resistance tester so as to obtain the state change of the tested member and provide basis for evaluation on the structure bearing capacity. Test equipment adopted by the method is easy to change and simple in test process and can realize periodic detection and continuous monitoring.

Description

A kind of bridge wire steel beam column detection method

Technical field

The present invention relates to Bridge Inspection, particularly relate to a kind of bridge wire steel beam column detection method, be applicable to the component that length-diameter ratio is larger, as regular reinforcement, prestress wire, steel strand stay cable, parallel steel wire suspension cable etc., belong to the field of non destructive testing of the fixing structures such as bridge.

Background technology

Wire steel are key members of bridge, as the regular reinforcement in reinforced beam mainly bears pulling force, match with concrete compression, and opposing external load moment of flexure, the weakening of regular reinforcement cross section causes structural bearing capacity to decline, and affects structural safety.Steel strand wires in prestressed concrete are for adjusting section stress, concrete is made to lay in compressive stress, the tension that opposing external load produces, loss of prestress causes concrete cracking, the downwarp of beam body, this type of disease is comparatively common in large-span continuous beam, Continuous Rigid-Frame Bridge, has a strong impact on structural safety.The suspension cable of cable-stayed bridge bears dead load and the mobile load of girder, is passed to foundation structure by king-tower, and the suspension cable cross section of causing due to burn into fracture of wire etc. weakens the inherently safe directly affecting suspension cable, thus threatens the safety of bed rearrangement stayed-cable bridge structure system.

Detection method at present for wire steel state all has certain limitation.

For reinforced concrete structure, in " highway bridge load-bearing capacity detecting appraisal code ", assessment thought detects based on extent of steel corrosion, all adopt Indirect Detecting Method, as steel bar corrosion potentiometric detection, chloride ion content detection, Resistivity testing, carbonization condition detection, the shortcoming of these detection methods detects data discrete greatly, and assessment result is easily by artificial interference.

For the component such as prestress wire, suspension cable, usually adopt Suo Li to detect the method (as Spectrum Method, rope meter, pressure rings, magnetic flux transducer) of (monitoring) at present, carry out structural appraisal by Suo Li change.The greatest drawback of these methods is that the cross section that only can not find the corrosion of cable body inner wire (or steel strand wires) according to Suo Li result, fracture of wire causes weakens, load-bearing capacity and the residual life of cable body can not be assessed, limited to the decision support of bridge management maintenance.Also there is equipment durability problem in rope meter, pressure rings, magnetic flux transducer etc., this equipment needs synchronously to install when cable body stretch-draw, and restricted lifetime, bridge generation disease then often occurs in and is open to traffic for many years, now device data confidence level greatly reduces, and is not easy to change; Such as not having at present for the steel strand prestress bundle not installing rope meter at the beginning can practical check and evaluation method.

Summary of the invention

In view of this, the invention provides a kind of bridge wire steel beam column detection method simple to operate.

A kind of bridge wire steel beam column detection method, it is for detecting the prestress of tested wire steel beam column, and described bridge wire steel beam column detection method comprises the following steps:

The resistance value scope of tested wire steel beam column is calculated according to the parameter of tested wire steel beam column;

The wire that need connect is determined according to the resistance value scope of calculated tested wire steel beam column;

Determine the end positions of tested wire steel beam column and will by corresponding respectively to two web members, two wires, tested wire steel beam column be connected with a precision resistance tester respectively;

The test gear of selected described precision resistance tester starts to measure.

Further, described tested wire steel beam column is regular reinforcement, prestress wire or suspension cable.

Compared with prior art, in bridge wire steel beam column detection method provided by the invention, tested wire steel beam column itself is sensor, by first calculating the resistance value of tested component, recycling precision resistance tester passes through the actual resistance of web member and wire test member, analytical test result draws the state change of tested component, and for structural bearing force estimation provides foundation, the testing apparatus that the method adopts is easy to change, test process is simple, realize periodic detection and monitor continuously.

Accompanying drawing explanation

Fig. 1 is the process flow diagram of bridge wire steel beam column detection method of the present invention.

Fig. 2 is the circuit diagram that the detection method of Fig. 1 connects when detecting.

Main element symbol description

Web member 110a, 110b

Wire 120a, 120b

Precision resistance tester 140

Tested wire steel beam column 10

Following embodiment will further illustrate the present invention in conjunction with above-mentioned accompanying drawing.

Embodiment

Refer to Fig. 1, it is a kind of bridge wire steel beam column detection method provided by the invention, it is for detecting the prestress of wire steel beam column 10 tested in Fig. 2, described tested wire steel beam column 10 is regular reinforcement, prestress wire or suspension cable, be understandable that, resistance is a kind of fundamental property of conductor, and resistance value size is generally relevant with temperature, material, length, cross-sectional area.Bridge wire steel beam column 10 material is generally alloy steel products, bridge is once build up, the material of each component, length, cross-sectional area are determined all, temperature variation is also learnt by test, then the resistance of bridge wire steel beam column 10 is metastable values, by the state of the measurement reactive means of resistance value.

The general characteristic of bridge steel structural unit is that sectional area and length are all larger, resistance value is less, and increased resistance value is less, for reaching the object of state-detection, then need precision resistance measuring technique, precision resistance measuring technique is that the state-detection of bridge steel structural unit provides technical support.Precision resistance tester is a kind of high-accuracy wide-range, the precision resistance tester adopting high-performance microprocessor control, the resistance of 0.1 μ Ω ~ 110M Ω can be measured, basic accuracy reaches 0.01%, can manually gather, also can automatically gather, sample frequency can reach 150Hz, is applicable to doing periodic detection and automatic monitoring.

Based on precision resistance measuring technique, comprise the following steps when the prestress of described detection method to tested wire steel beam column 10 detects:

S1: the resistance value scope calculating tested wire steel beam column according to the parameter of tested wire steel beam column;

S2: determine the wire that need connect according to the resistance value scope of calculated tested wire steel beam column;

S3: determine the end positions of tested wire steel beam column and will by corresponding respectively to two web members, two wires, tested wire steel beam column be connected with precision resistance tester respectively;

S4: the test gear of selected precision resistance tester starts to measure.

In step sl, testing staff determines the initial parameter such as material, length, theoretical sectional area, control stress for prestressing of tested wire steel beam column according to the design drawing of bridge structure, estimate stress loss scope, calculate the resistance value scope of tested component, such as, in fig. 2, the length of one section in bridge structure tested wire steel beam column 10 is l, sectional area is A, and resistivity is the component of ρ, and resistance calculations formula is as follows:

$R=\mathrm{\ρ}\frac{l}{A}---\left(1\right)$

Trying to achieve the formula that above-mentioned resistance changes relatively is:

$\frac{dR}{R}=\frac{dl}{l}-\frac{dA}{A}+\frac{d\mathrm{\ρ}}{\mathrm{\ρ}}---\left(2\right)$

Section 1 can the stress loss of reactive means in formula (2), and Section 2 can cross section loss (comprising fracture of wire) of reactive means, by the impact of temperature coefficient correction deduction temperature.

For the prestress wire that prestressed concrete beam bridge is conventional, to be that the steel wire of 7 diameter 5mm is stranded form model, gets steel strand wires electricalresistivityρ=0.2 × 10 ^-6resistance value about 1 Ω under standard temperature of the long steel strand wires core wire of Ω m, 100m.The control stress for prestressing of prestressing with bond steel strand wires is 1395MPa, thus resistance value increment about 0.023 Ω.Consider loss of prestress 1%, resistance value increment about 0.00023 Ω, i.e. 230 μ Ω, this resistance delta accurately can be recorded by the precision resistance tester 140 arranged in Fig. 2.

In step s 2, the resistance value scope of the tested wire steel beam column 10 calculated according to formula (1), to determine the parameter of wire, as parameters such as length, sectional area, resistivity, thus measures the precise resistances of wire according to corresponding parameter.

In step s3, as shown in Figure 2, one end of web member 110a is connected to one end of tested wire steel beam column 10, one end of web member 110b is connected to the other end of tested wire steel beam column 10, and the other end of two web members 110a, 110b is corresponding to be respectively connected to precision resistance tester 140 through two wires 120a, 120b and to measure.

In step s 4 which, the test gear that testing staff carrys out selected precision resistance tester 140 according to the resistance value scope of the tested wire steel beam column 10 calculated and the wire determined starts to measure, and also needs the temperature measuring tested wire steel beam column 10 simultaneously.By the actual resistance (make temperature and return process) of precision resistance tester 140 periodic measurement bridge wire steel beam column 10, draw the state change of steel beam column 10 according to the change of resistance value, the state that can reflect change comprises stress loss, cross section weakening, fracture of wire etc.

Tested wire steel beam column 10 is included in the link circuit shown in Fig. 2, if web member 110a, 110b in loop and wire 120a, 120b form by copper cable, copper cable resistivity is low, such as, get sectional area 20mm ², the copper cable of length 100m, its resistance value about 0.085 Ω, the resistance change of above-mentioned loss of prestress 1% accounts for 0.02% of loop total resistance value.It is comparatively obvious that cross section weakens the resistance change caused, and as cross section loss 1%, from formula (2), resistance change is 1%; The cross section loss that fracture of wire causes is larger, is easier to measure find.

In bridge wire steel beam column detection method provided by the invention, tested wire steel beam column 10 itself is sensor, first calculate the resistance value of tested wire steel beam column, recycling precision resistance tester 140 is by web member 110a, 110b and wire 120a, 120b tests the actual resistance of tested wire steel beam column 10 to reflect the state change of bridge steel structural unit 10, comprise stress loss, cross section weakens, fracture of wire etc., the state of accurate evaluation component, and then Efficient Evaluation is carried out to one-piece construction, for bridge maintenance management decision provides direct basis, the testing apparatus that this detection method adopts simultaneously is easy to change, cost is low, test process is simple, test result is directly perceived, the periodic detection of Life cycle can be realized and monitor continuously.

Be understandable that, for the person of ordinary skill of the art, other various corresponding change and distortion can be made by technical conceive according to the present invention, and all these change the protection domain that all should belong to the claims in the present invention with distortion.

Claims (2)

1. a bridge wire steel beam column detection method, it is for detecting the prestress of tested wire steel beam column, and described bridge wire steel beam column detection method comprises the following steps:

The resistance value scope of tested wire steel beam column is calculated according to the parameter of tested wire steel beam column;

The wire that need connect is determined according to the resistance value scope of calculated tested wire steel beam column;

Determine the end positions of described tested wire steel beam column and will by corresponding respectively to two web members, two wires, tested wire steel beam column be connected with a precision resistance tester respectively;

The test gear of selected described precision resistance tester starts to measure.

2. bridge wire steel beam column detection method as claimed in claim 1, it is characterized in that, described tested wire steel beam column is regular reinforcement, prestress wire or suspension cable.