CN102661784A - Frequency detection method for steel roof truss damage diagnosis - Google Patents
Frequency detection method for steel roof truss damage diagnosis Download PDFInfo
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- CN102661784A CN102661784A CN2012101292258A CN201210129225A CN102661784A CN 102661784 A CN102661784 A CN 102661784A CN 2012101292258 A CN2012101292258 A CN 2012101292258A CN 201210129225 A CN201210129225 A CN 201210129225A CN 102661784 A CN102661784 A CN 102661784A
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- roof truss
- steel roof
- additional mass
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Abstract
The invention discloses a frequency detection method for steel roof truss damage diagnosis. The method includes 1 randomly selecting one node in a steel roof truss and installing a detachable mass block on the node; 2 utilizing a dynamic data collection system to measure low order natural frequency of vibration of the steel roof truss with added mass block; 3 disassembling the additional mass block, selecting other nodes of the steel roof truss, installing the additional mass block on the nodes and measuring the low order natural frequency of vibration of the steel roof truss with the added mass block at the new position; and 4 repeating the above processes. The frequency detection method adopts an additional mass method of the additional mass block, is simple in structure, low in cost, capable of conveniently obtaining enough frequency information for damage diagnosis of the steel roof truss structure, simple and convenient to operate and implement and high in diagnosis accuracy.
Description
Technical field
The invention belongs to the structural failure diagnostic field of civil engineering work subject, relate to a kind of frequency detecting method of steel roof truss damage.
Background technology
The widespread use in many industry and covil construction of steel roof truss structure.Because the growth of Years Of Service, and the influence of environmental corrosion, disaster load etc., the accident that steel roof truss collapses has happened occasionally, presses for its damage status is made diagnosis timely, so that the consequence of averting a calamity property of maintenance and reinforcement takes place.
Mostly traditional damage diagnosis method is the experimental technique of visual part, like ultrasonic method, methods of magnetic field, temperature field method etc.The general requirement of these methods knows probably that in advance damage position and position to be detected equipment can arrive, so workload expends height greatly, and is not suitable for the damage of large scale civil engineering structure.
Utilize the variation of steel roof truss structural vibration parameter to judge that the method for its damage status is present a kind of new technology.This technology is through the vibration parameters before and after the collection structural damage, and the finite element model of integrated structure judges whether structure is damaged, the position of damage and degree.
Wherein, gather the key link that vibration parameters as much as possible is above-mentioned new diagnostic techniques.Usually, steel roof truss structural vibrations parameter comprises the frequency and the vibration shape, and the measurement of frequency only need arrange that a measuring point can carry out, and easy operating and precision are very high; And a large amount of measuring points need be structurally arranged in the measurement of the vibration shape and link to each other with data acquisition instrument through a large amount of leads, and it is lower to implement ten minutes difficulty and measuring accuracy.Therefore, frequency just becomes the most widely used parameter in the damage.But in the prior art of engineering practice at present, can only collect a few low order frequency parameter, can not satisfy the needs of steel roof truss diagnosing structural damage under a lot of situation.
In view of this, the inventor combines to be engaged in steel roof truss structure area research work experience for many years, and the defective of above-mentioned technical field is studied for a long period of time, and this case produces thus.
Summary of the invention
The object of the present invention is to provide a kind of frequency detecting method of steel roof truss damage; Adopt the additional mass method of additional mass; Simple in structure, with low cost; Can obtain the damage that abundant frequency information is used for the steel roof truss structure easily, operation is implemented simple and convenient, and the accuracy of diagnosis is higher.
To achieve these goals, technical scheme of the present invention is following:
A kind of frequency detecting method of steel roof truss damage may further comprise the steps: at first, choose certain node in the steel roof truss arbitrarily and the dismountable auxiliary mass is installed on this node; Secondly, utilize dynamic data collection system to measure the natural frequencies of steel roof truss vibration behind the additional mass; The 3rd, remove additional mass, choose other node of steel roof truss and additional mass is installed on it, continue to utilize the natural frequencies that steel roof truss vibrates behind the position additional mass that dynamic data collection system measurements make new advances; The 4th, repeat above process, up to obtain abundant can satisfy the frequency information that damage requires till.
Further; Said additional mass comprises two identical square iron plates; The size of iron plate is decided according to the steel roof truss size of node; Two iron plate symmetries are clipped in the middle the steel roof truss node and fix through 4 the identical installation screws in four jiaos of places, and two iron plates and 4 installation screws constitute additional mass jointly.Thereby easy to operate, additional mass can be reused, and the simple implementation cost of equipment is low, and does not influence the operate as normal of steel roof truss, is beneficial to conveniently, image data etc. accurately.
Further, said dynamic data collection system comprises a wireless senser and a wireless Dynamic Data Acquiring appearance, and sensor is fixedly installed in a square iron plate center in the additional mass.Thereby data acquisition is convenient, accurate, and cost is cheap, and does not influence the operate as normal of steel roof truss again; Its wireless senser is fixedly installed on the iron plate in the additional mass, has avoided need sensor being installed on the defective on the engineering structure in the prior art, implements easily, and can be repeatedly used in different steel roof truss structures.
Using additional mass, to gather the low order frequency process of steel roof truss vibration following: choose certain node in the steel roof truss at first arbitrarily and above-mentioned additional mass is installed on this node, measure the low order frequency of steel roof truss vibration this moment; Change the installation site (promptly choosing other node in addition is installed on it additional mass) of additional mass then, and measure the low order frequency of the pairing steel roof truss vibration in the installation site that makes new advances; Repeat said process, till the frequency information of measuring enough numbers.The present technique scheme can obtain more, and the principle of multi-frequency information is: the vibration characteristics of steel roof truss will take place obviously to change behind the installation additional mass, and different installation sites will cause that different vibration characteristics changes.The steel roof truss of additional mass is not installed, and its vibration frequency number is a determined value.And the steel roof truss of additional mass has been installed, the every replacing in the installation site of additional mass once can be measured and obtains and the same number of frequency parameter of additional mass steel roof truss is not installed.Therefore, along with the variation of additional mass installation site, the frequency number of measuring gained will be doubled and redoubled, till satisfying the needed frequency number of damage.
Useful achievement of the present invention is: the first, adopt the additional mass of easy installation and removal in the present technique scheme, can with the node fixing compact, and can not change the topological structure of structural model; The second, through the installation site of conversion additional mass, can obtain abundant frequency information easily to satisfy the needs of damage, overcome the defective of existing method frequency information quantity not sufficient; The 3rd, the present invention has simple to operation, and additional mass and dynamic data collection system can be reused; The 4th, adopt the present technique scheme, the simple implementation cost of equipment needed thereby is low, and does not influence the operate as normal of steel roof truss; The 5th, adopt the present invention can obtain the needs that abundant frequency information satisfies damage easily, thereby accuracy is higher.
In order further to explain technical scheme of the present invention, the present invention is done further detailed description below in conjunction with accompanying drawing and embodiment.
Description of drawings
Fig. 1 is additional mass of the present invention and dynamic data collection system synoptic diagram.1 is square iron plate in wherein scheming; The 2nd, screw is installed; 1 and the 2 common additional masses of forming; The 3rd, wireless senser; The 4th, the Dynamic Data Acquiring appearance; The 5th, the steel roof truss node; The 6th, the steel roof truss rod member.
Fig. 2 is a plane steel roof truss model to be detected, and wherein 1-12 is that steel roof truss node, (1)-(23) are the steel roof truss rod member among the figure.
Embodiment
Below in conjunction with accompanying drawing to enforcement further detailed description of the present invention.
As shown in Figure 1, Fig. 1 is the additional mass synoptic diagram among the present invention.Described additional mass comprises two installation screws 2 that identical square iron plate 1 is identical with 4, and two iron plate symmetries are clipped in the middle the steel roof truss node during installation, with 4 screw is installed and is fixed.Two iron plates and 4 installation screws constitute additional mass jointly.Dynamic data collection system comprises Dynamic Data Acquiring instrument of a wireless senser, and sensor is fixedly installed in a square iron plate center in the additional mass.Thereby data acquisition is convenient, accurate, and cost is cheap, and does not influence the operate as normal of steel roof truss again; Its wireless senser is fixedly installed on the iron plate in the additional mass, has avoided need sensor being installed on the defective on the engineering structure in the prior art, implements easily, and can be repeatedly used in different steel roof truss structures.
The length of side of the square iron plate 1 of additional mass is 500mm in the present embodiment, and thickness is 20mm, and four jiaos of places of described iron plate offer 4 mounting holes, and described mounting hole is a threaded hole, is the circular hole of diameter 16mm.Described installation screw 2 is cylindrical, and long 500mm, diameter are 16mm.Thereby easy to operate, additional mass can be reused, and the simple implementation cost of equipment is low, and does not influence the operate as normal of steel roof truss, is beneficial to conveniently, image data etc. accurately.Sensor 3 adopts Wireless Acceleration Sensor, pastes to be installed on the square iron plate 1.Dynamic Data Acquiring appearance 4 adopts wireless Dynamic Data Acquiring appearance, can export vibration frequency information.This equipment can be bought from market.
Fig. 2 is a plane steel roof truss model to be detected; This structure basic parameter is: elastic modulus
; Density
; Every rod member length
; The rod member xsect is a square, cross-sectional area
.For the Simulation Damage situation, suppose rod member 10 losss of rigidity 20% among Fig. 2 in advance.
Adopt the present technique scheme following: at first, dismountable auxiliary mass (1+2) to be installed on the node 2 of Fig. 2 steel roof truss to the mode that plane steel roof truss shown in Figure 2 carries out damage; Secondly, utilize dynamic data collection system (3+4) to measure the natural frequencies of steel roof truss vibration behind the additional mass; The 3rd, remove additional mass, with its node 3 places that are installed on steel roof truss, continue to utilize dynamic data collection system to measure additional mass after
Steel roof trussVibration frequency; The 4th, repeat above process, up to obtain abundant can satisfy the frequency information that damage requires till.
The frequency information of above-mentioned acquisition can be used as the input information of damage program, and then draws the damage result of steel roof truss.As for the damage program; Can adopt the program of existing other people braiding; Also can adopt programming that the inventor creates; A kind of damage program of uniqueness also is provided in the patent of invention that the inventor applies at the same time, in the damage program that the input of the frequency information of above-mentioned measurement gained is woven, just can have drawn the diagnostic result of steel roof truss damage position and degree.This steel roof truss damage program comprises following part: at first, set up the finite element model of steel roof truss structure with numerical analysis software; Then, calculate preceding frequency and the correspondent frequency sensitivity of steel roof truss damage, thereby set up the frequency sensitivity equation of steel roof truss according to finite element model; At last, with the impairment parameter that solves each unit of steel roof truss in the frequency information incoming frequency sensitivity equation of measuring gained, the impairment parameter output of calculating gained can be made diagnosis to the damage position and the degree of steel roof truss.
From last we can find out that want the accurate and effective damage position of making steel roof truss and the diagnostic result of degree, it is crucial adopting the present technique scheme to obtain a plurality of frequency informations accurately.
Adopt the additional mass of easy installation and removal in the present technique scheme, can with the node fixing compact, and can not change the topological structure of structural model; Secondly,, can obtain abundant frequency information easily, overcome the defective of existing method frequency information quantity not sufficient to satisfy the needs of damage through the installation site of conversion additional mass; The 3rd, the present invention has simple to operation, and additional mass and dynamic data collection system can be reused, and the simple implementation cost of equipment is low, and does not influence the advantages such as operate as normal of steel roof truss; The 4th, adopt the present technique scheme, the simple implementation cost of equipment needed thereby is low, and does not influence the operate as normal of steel roof truss; The 5th, can obtain the needs that abundant frequency information satisfies damage easily, and the damage result is accurately and reliably.
Adopt such scheme; Through additional mass on steel roof truss; And measure the natural frequencies of steel roof truss vibration behind the additional mass by the dynamic data measuring system; Finite element model by steel roof truss calculates its frequency sensitivity again, can calculate the impairment parameter of each unit of steel roof truss according to frequency shift amount and the frequency sensitivity equation of measuring gained at last, just can make diagnosis to the damage position and the degree of steel roof truss in view of the above.
The method that this case is carried; Only need a wireless senser; And sensor is installed on the additional mass, has avoided existing method sensor will be installed on structural defective, and easy operating is implemented; And can obtain to be used for damage than the more frequency information of raw steel roof truss structure, can increase substantially the accuracy of damage.
The above is merely specific embodiment of the present invention, is not the restriction to this case design, and all equivalent variations of doing according to the design key of this case all fall into the protection domain of this case.
Claims (3)
1. the frequency detecting method of a steel roof truss damage is characterized in that: may further comprise the steps: at first, choose certain node in the steel roof truss arbitrarily and the dismountable auxiliary mass is installed on this node; Secondly, utilize dynamic data collection system to measure the natural frequencies of steel roof truss vibration behind the additional mass; The 3rd, remove additional mass, choose other node of steel roof truss and additional mass is mounted thereon, continue to utilize the natural frequencies that steel roof truss vibrates behind the position additional mass that dynamic data collection system measurements make new advances; The 4th, repeat above process, up to obtain abundant can satisfy the frequency information that damage requires till.
2. the frequency detecting method of a kind of steel roof truss damage as claimed in claim 1; It is characterized in that: said additional mass comprises two identical square iron plates; The size of iron plate is decided according to the steel roof truss size of node; Two iron plate symmetries are clipped in the middle the steel roof truss node and fix through 4 the identical installation screws in four jiaos of places, and two iron plates and 4 installation screws constitute additional mass jointly.
3. the frequency detecting method of a kind of steel roof truss damage as claimed in claim 2; It is characterized in that: said dynamic data collection system comprises a wireless senser and a wireless Dynamic Data Acquiring appearance, and sensor is fixedly installed in a square iron plate center in the additional mass.
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| CN2012101292258A CN102661784A (en) | 2012-04-28 | 2012-04-28 | Frequency detection method for steel roof truss damage diagnosis |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102662031A (en) * | 2012-05-11 | 2012-09-12 | 绍兴文理学院 | Frequency detector for steel roof truss damage diagnosis |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07270227A (en) * | 1994-03-31 | 1995-10-20 | Hitachi Ltd | Fluid/structure compound vibration analysis method |
| US20080294354A1 (en) * | 2003-05-20 | 2008-11-27 | University Of Maryland, Baltimore County | System and method for detecting structural damage |
-
2012
- 2012-04-28 CN CN2012101292258A patent/CN102661784A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07270227A (en) * | 1994-03-31 | 1995-10-20 | Hitachi Ltd | Fluid/structure compound vibration analysis method |
| US20080294354A1 (en) * | 2003-05-20 | 2008-11-27 | University Of Maryland, Baltimore County | System and method for detecting structural damage |
Non-Patent Citations (3)
| Title |
|---|
| 《中国优秀硕士学位论文全文数据库 工程科技Ⅱ辑》 20091215 张佳文 基于振动特性的结构损伤识别方法研究 第31页至第37页，图3.7、3.8 1 , 第12（2009年）期 * |
| 张佳文: "基于振动特性的结构损伤识别方法研究", 《中国优秀硕士学位论文全文数据库 工程科技Ⅱ辑》, no. 122009, 15 December 2009 (2009-12-15) * |
| 杨秋伟等: "结构损伤识别的附加质量方法", 《工程力学》, vol. 26, no. 5, 31 May 2009 (2009-05-31) * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102662031A (en) * | 2012-05-11 | 2012-09-12 | 绍兴文理学院 | Frequency detector for steel roof truss damage diagnosis |
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Application publication date: 20120912 |