CN110276089B - Method for estimating average axial force of cable clamp screw of suspension bridge - Google Patents
Method for estimating average axial force of cable clamp screw of suspension bridge Download PDFInfo
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- G06F30/13—Architectural design, e.g. computer-aided architectural design [CAAD] related to design of buildings, bridges, landscapes, production plants or roads
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Abstract
The invention discloses a method for estimating the average axial force of a cable clamp screw of a suspension bridge, which determines the elongation delta L of a main cable at the nth stage according to N stages of a suspension beam n Based on the total length L, delta L of the front main cable of the hanging beam n Calculating the actual diameter d 'of the single steel wire according to the theoretical diameter d' of the single steel wire, and calculating the cross-sectional area variation Delta s of the single steel wire according to the d and the d 1 And the change amount deltas of the cross-sectional gap area between the steel wires 2 According to the total number M of wires 1 Total number of gaps M 2 、Δs 1 And Δ s 2 Calculating the total variation Delta S of the cross-sectional area of the main cable n According to Δ S n Calculating the diameter variation delta D of the main cable, and calculating the loss value delta F of the average axial force of the screw rod of the cable clamp according to the average axial force F of the cable clamp of the main cable in front of the hanging beam, the average elongation delta l and delta D of the screw rod n And the cable clamp screw average axial force value F'. The estimation method provided by the invention can calculate the average axial force change condition of the cable clamp screw rod of the suspension bridge at each stage in the process of hanging the beam, and provides important technical support for the construction of the suspension bridge.
Description
Technical Field
The invention relates to the technical field of bridge engineering construction, in particular to a method for estimating the average axial force of a cable clamp screw of a suspension bridge.
Background
The suspension bridge cable clamp is one of main components of an upper structure of a suspension bridge, and the main defect in the using process is that the cable clamp slides on a main cable, and the main reason is mainly caused by insufficient fastening force of a cable clamp screw rod. China's highway bridge culvert maintenance code (2004) 3.3.9 requires to check whether the cable clamp of the upper end of the suspension bridge suspender and the main cable is loosened, displaced and damaged, and the cable clamp slippage greater than 10mm is also regarded as serious defect in the highway bridge technical condition evaluation standard (2011) 7.2.1.
During construction and construction of the suspension bridge, construction of the suspension beam is a process with great technical difficulty and potential safety hazards, particularly, in the process of the suspension beam, a main cable continuously bears, extends and becomes thin, axial force of a cable clamp screw rod continuously loses and is loosened, and potential construction potential hazards can be caused. The dynamic change is a technical problem, a proper method for evaluating the trend change condition of the axial force loss of the cable clamp screw rod is not available in the existing construction design technical scheme, during actual beam hanging, due to lack of corresponding technical guidance, the existing construction scheme is only tensioned as soon as possible and continuously detected, but for the dynamic change of the axial force of the screw rod continuously lost along with the load bearing of a main cable of the beam hanging, engineering construction and monitoring technicians still have no method for evaluating and confirming and can only make basic judgment according to previous experience, so that the repeated operation of the tensioning work and the axial force detection work of the screw rod is caused, and otherwise, the dangerous condition of cable clamp slippage exists in the construction of a certain bridge.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a method for estimating the average axial force of a cable clamp screw of a suspension bridge, which can calculate the change condition of the average axial force of the cable clamp screw of the suspension bridge at each stage in the process of hanging a beam, thereby making a certain evaluation, providing important technical support for the construction and construction of the suspension bridge and ensuring the safe construction and construction of the bridge.
In order to achieve the above purposes, the technical scheme adopted by the invention is as follows:
determining the elongation delta L of the main cable at the nth stage according to the N stages of the hanging beam n N is more than or equal to 1 and less than or equal to N, and the total length L and delta L are based on the main cable in front of the hanging beam n Calculating the actual diameter d' of the single steel wire in the nth stage according to the theoretical diameter d of the single steel wire;
calculating the variable quantity deltas of the cross-sectional area of a single steel wire in the nth stage according to d and d 1 And the cross-sectional gap area variation deltas between the steel wires 2 ；
According to the total number M of steel wires 1 And the total number M of gaps among the steel wires 2 、Δs 1 And Δ s 2 Calculating the total variation Δ S of the cross-sectional area of the main cable at the nth stage n According to Δ S n Calculating the diameter variation delta D of the main cable at the nth stage;
calculating the loss value delta F of the average axial force of the screw rod of the cable clamp in the nth stage according to the average axial force F of the main cable clamp in front of the hanging beam and the average elongation delta l and delta D of the screw rod n According to Δ F n Calculating the n-th stage of the cable clamp screwBar mean axial force value F'.
Based on the technical scheme, the method is based on a formula
Calculating the elongation Delta L of the main cable at the nth stage n And wherein Δ L is the theoretical main cable elongation after the suspension beam is finished.
Based on the technical scheme, the method is based on a formula
The actual diameter d' of the single wire at the nth stage is calculated, where μ is a constant and has a value of 0.25.
Based on the technical scheme, the method is based on a formula
Calculating the variable quantity deltas of the cross-sectional area of a single steel wire in the nth stage 1 。
Based on the technical scheme, the method is based on a formula
Calculating the area variation Delta s of the cross-section gap between the steel wires at the nth stage 2 。
Based on the technical scheme, the method is based on a formula
ΔS n ＝M1*Δs 1 +M2*Δs 2
Calculating the total variation Delta S of the cross-sectional area of the main cable in the nth stage n 。
Based on the technical scheme, the method is based on a formula
ΔD＝D-D′
And sequentially calculating the actual diameter D' of the main cable and the diameter variation delta D of the main cable in the nth stage, wherein D is the diameter value of the fixed cable clamp after the main cable is erected.
Based on the technical scheme, the method is based on a formula
F′＝F-ΔF n
Calculating the loss value delta F of the average axial force of the cable clamp screw rod in the nth stage in sequence n And the cable clamp screw average axial force value F'.
Based on the technical scheme, the method is based on a formula
Calculating the average elongation delta l of the front screw rod of the hanging beam, wherein l Screw thread Is the nominal length of the screw, d Screw thread The nominal diameter of the screw and E the modulus of elasticity, which is 209GPa.
Compared with the prior art, the invention has the advantages that:
according to the method for estimating the average axial force of the cable clamp screw of the suspension bridge, provided by the invention, on a construction site, the average axial force of the cable clamp screw at each stage can be sequentially calculated according to a plurality of formulas by only measuring parameters such as the total length L of a main cable in front of a suspension beam, the average axial force F of a main cable clamp and the theoretical main cable elongation delta L after the suspension beam is finished.
Detailed Description
The following examples of the present invention are described in further detail.
The embodiment of the invention provides an estimation method for the average axial force of a cable clamp screw of a suspension bridge. Specifically, the elongation Δ L of the main cable at the nth stage is determined according to the N stages of the suspension beam n N is more than or equal to 1 and less than or equal to N, based on the total length L of the main cable in front of the hanging beam and the elongation delta L of the main cable at the nth stage n And calculating the actual diameter d' of the single steel wire in the nth stage by using the theoretical diameter d of the single steel wire, wherein the total length L of the main cable in front of the hanging beam is the factory leaving length, the main cable is generally marked and is a known length, and the theoretical diameter d of the single steel wire of the main cable of the suspension bridge generally takes a value of 6.22mm.
Secondly, calculating the variation deltas of the cross-sectional area of the single steel wire in the nth stage according to the theoretical diameter d of the single steel wire and the actual diameter d' of the single steel wire in the nth stage calculated above 1 And the change amount deltas of the cross-sectional gap area between the steel wires 2 . Because the bearing capacity that the main push-towing rope receives is different at the different stages of hanging beam, consequently compare initial length, the main push-towing rope can lengthen, and corresponding single steel wire that constitutes the main push-towing rope all can change.
Then, according to the total number M of steel wires in the main cable 1 And the total number M of gaps among the steel wires 2 And the cross-sectional area variation Delta s of a single steel wire in the nth stage 1 And the change amount deltas of the cross-sectional gap area between the steel wires 2 Calculating the total variation Δ S of the cross-sectional area of the main cable at the nth stage n Then according to Δ S n And calculating the diameter variation quantity delta D of the main cable at the nth stage.
Finally, the average axial force F of the main cable clamp in front of the hanging beam, the average elongation delta l of the screw rod and the diameter variation delta D of the main cable in the nth stage are calculatedCalculating the loss value delta F of the average axial force of the cable clamp screw rod in the nth stage n According to Δ F n And calculating the average axial force value F' of the cable clamp screw at the nth stage. The average axial force F of the main cable clamp in front of the suspension beam is obtained by measuring the axial force of all screws on the cable clamp by a technician through an axial force ultrasonic detector and then averaging.
In particular, according to the formula
Calculating to obtain the elongation delta L of the main cable at the nth stage n And the delta L is the theoretical main cable elongation after the suspension beam is finished and is obtained through finite element calculation analysis.
In particular, according to the formula
And calculating the actual diameter d' of the single steel wire in the nth stage, wherein mu is a constant, the value of mu ranges from 0.2 to 0.3, and the value of mu is 0.25 according to the type and the material of the main cable.
In particular, according to the formula
Calculating the cross-sectional area variation deltas of a single steel wire in the nth stage 1 Where Δ s 1 Is the difference between the cross-sectional area of a single steel wire at the nth stage and the cross-sectional area of the single steel wire in front of the hanging beam.
In particular, according to the formula
Calculating the area variation Delta s of the cross-section gap between the steel wires at the nth stage 2 And the main cable is stretched and thinned under the action of bearing force, so that gaps between the steel wires can be reduced in the thinning process.
In particular, according to the formula
ΔS n ＝M1*Δs 1 +M2*Δs 2
Calculating the total variation Delta S of the cross-sectional area of the main cable in the nth stage n Total amount of change in cross-sectional area Δ S n Is the sum of the variation of the diameter of the total steel wire and the variation of the gap.
In particular, according to the formula
ΔD＝D-D′
And sequentially calculating the actual diameter D' of the main cable and the diameter variation delta D of the main cable in the nth stage, wherein D is the diameter value of the fixed cable clamp after the main cable is erected, and a technician can measure the diameter value by using a conventional measuring tool.
In particular, according to the formula
F′＝F-ΔF n
Calculating the loss value delta F of the average axial force of the cable clamp screw rod in the nth stage in sequence n And subtracting the loss value from the average axial force value of the cable clamp screw in front of the hanging beam to obtain the average axial force value F' of the cable clamp screw.
In particular, according to the formula
Calculating the average elongation delta l of the front screw rod of the hanging beam, wherein l Screw thread Is the nominal length of the screw, d Screw thread Is the nominal diameter of the screw, is a known value, E is the modulus of elasticity, which is the value209GPa。
Compared with the prior art that the average axial force F of the main cable clamp needs to be measured at each stage through manpower and tools, the estimation method provided by the invention can be used for sequentially calculating the average axial force value of the cable clamp screw rod at each stage according to the plurality of formulas only by measuring the parameters such as the total length L of the main cable in front of the hanging beam, the average axial force F of the main cable clamp, the theoretical main cable elongation delta L after the hanging beam is finished and the like at the construction site.
The present invention is not limited to the above-mentioned preferred embodiments, and any other products in various forms can be obtained by anyone with the teaching of the present invention, but any changes in the shape or structure thereof, which have the same or similar technical solutions as the present invention, are within the protection scope.
Claims (9)
1. A method for estimating the average axial force of a cable clamp screw of a suspension bridge is characterized by comprising the following steps:
determining the elongation delta L of the main cable at the nth stage according to the N stages of the hanging beam n N is more than or equal to 1 and less than or equal to N, and the total length L and delta L are based on the main cable in front of the hanging beam n Calculating the actual diameter d' of the single steel wire in the nth stage according to the theoretical diameter d of the single steel wire;
calculating the cross-sectional area variation deltas of a single steel wire in the nth stage according to d and d 1 And the cross-sectional gap area variation deltas between the steel wires 2 ；
According to the total number M of steel wires 1 And the total number M of gaps among the steel wires 2 、Δs 1 And Δ s 2 Calculating the total variation Delta S of the cross-sectional area of the main cable at the nth stage n According to Δ S n Calculating the diameter variation delta D of the main cable at the nth stage;
calculating the loss value delta F of the average axial force of the screw rod of the cable clamp in the nth stage according to the average axial force F of the main cable clamp in front of the hanging beam and the average elongation delta l and delta D of the screw rod n According to Δ F n And calculating the average axial force value F' of the cable clamp screw at the nth stage.
2. The method of claim 1, wherein the method is based on a formula
Calculating the elongation Delta L of the main cable at the nth stage n And the delta L is the theoretical main cable elongation after the suspension beam is finished.
3. The method of claim 2, wherein the method is based on a formula
The actual diameter d' of the single wire at the nth stage is calculated, where μ is a constant and has a value of 0.25.
4. The method of claim 3, wherein the method is based on a formula
Calculating the cross-sectional area variation deltas of a single steel wire in the nth stage 1 。
5. The method of claim 4, wherein the method is based on a formula
Calculating the area variation Delta s of the cross-section gap between the steel wires at the nth stage 2 。
6. The method of claim 5, wherein the method is based on a formula
ΔS n ＝M1*Δs 1 +M2*Δs 2
Calculating the total variation Delta S of the cross-sectional area of the main cable in the nth stage n 。
7. The method of claim 6, wherein the method is based on a formula
ΔD＝D-D′
And sequentially calculating the actual diameter D' of the main cable and the diameter variation delta D of the main cable in the nth stage, wherein D is the diameter value of the fixed cable clamp after the main cable is erected.
8. The method of claim 7, wherein the method is based on a formula
F′＝F-ΔF n
Calculating the loss value delta F of the average axial force of the cable clamp screw rod in the nth stage in sequence n And the cable clamp screw average axial force value F'.
9. The method of claim 8, wherein the method is based on a formula
Calculating the average extension of the front screw of the hanging beamA long amount of Δ l, wherein l Screw nut Is the nominal length of the screw, d Screw nut E is the modulus of elasticity for the nominal diameter of the screw, and its value is 209GPa.
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| CN111623910B (en) * | 2020-05-25 | 2021-08-06 | 中铁大桥科学研究院有限公司 | Suspension bridge cable clamp screw axial force identification method based on ultrasonic echo envelope modeling |
| CN112227208B (en) * | 2020-09-23 | 2022-03-29 | 中铁大桥局集团有限公司 | Monitoring and forecasting method for construction period and operation period of suspension bridge cable clamp screw |
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| CN103174087B (en) * | 2013-04-01 | 2016-02-03 | 苏传海 | A kind of suspension cable-oblique pull co-operative system comprising inclination hoist cable and variable cross-section main push-towing rope |
| CN107587429B (en) * | 2017-08-04 | 2018-10-23 | 东南大学 | Cord clip of suspension bridge installation site modification method |
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