CN101294891B - Method for detecting glass curtain wall loosening and estimating falling risk - Google Patents

Abstract

The invention relates to a method for detecting loose glass curtain walls and predicting falling risks, which comprises the following steps (1) determining a glass reference frequency range according to the parameter of glass plate used in a glass curtain wall to be detected; (2) conducting a laboratory simulation test for the same glass plate; measuring inherent frequencies corresponding to different fixed states; obtaining a measurable frequency range Omega down and Omega up, and loose frequency Omega loose in the reference frequency range; conducting evaluation and classification by takingthe difference between the two extreme values, namely Omega down and Omega up, and the loose frequency, namely Omega loose as a security interval and a danger interval; (3) conducting vibration signal sampling and detection for the glass curtain wall in the field and obtaining the actually measured frequency of the glass curtain wall; and (4) comparing the actually measured frequency value with coherent frequency classification, and obtaining the safety and reliability grade of the glass curtain wall in the process of use.

Description

A kind of method that detects glass curtain wall loosening and prediction falling risk

Technical field

The present invention relates to the harmless online measuring technique of building curtain wall, be specifically related to a kind of method of testing the cladding glass safe reliability, its method of utilizing test cladding glass natural frequency and mechanics to combine can't harm online reliability testing to glass curtain wall, thus prediction glass curtain wall loosening and the risk of falling.

Background technology

Since the eighties in last century, China has built a large amount of glass-wall buildings in each big and medium-sized cities in succession.These buildings are mostly in the urban district of prosperity, any cladding glass together break or falling accident all may cause catastrophic consequence.In recent years, the potential safety hazard of cladding glass was more and more, had caused numerous experts and broad masses of the people's concern., constantly degenerate and decay as the various performances of the incorporate cladding glass of 26S Proteasome Structure and Function in year at a large amount of ten or twenties that use of cladding glass, glass curtain wall ubiquity just under arms security hidden trouble at present.Can be along with service time occurring catabiosis as the silicone structure sealant of fixed bonding agent, serious even chap and come off.Particularly for the concealed frame glass curtain wall that generally uses now, because such cladding glass does not have any housing, rely on fully and be adhesive on the aluminium type material surface, and need permanently effective opposing wind load, from heavy load, expand with heat and contract with cold, the influence of factor such as earthquake, it is greatly dangerous in case therefore structure sealant goes wrong.Frame supported and point support the loosening of curtain wall and equally also work the mischief, the loosening sealing and the heat preservation and soundproof performance that not only influences the room of curtain wall, more dangerous is possible cause falling of catastrophic high-altitude glass curtain wall, the cladding glass falling accident has repeatedly appearred in each big city of China, causes major disaster to society.

Performances such as the safe reliability of large glass, serviceable life and durability effectively assessment and the method determined of neither one also during one's term of military service so far, this is the big problem during cladding glass uses.

No matter be designing unit or applying unit, guarantee that the dependability of cladding glass all is very important and urgent building structure.For glass industry and building trade, the expense that is applied in building curtain wall glass every year is up to several hundred million units, if it obviously is a heavy losses that overdue cladding glass is all changed, if but do not do safety detection, disaster accident of every generation, its economic loss also can't the apparatus volume data be weighed.Therefore, research is to the new method of the harmless online reliability testing of glass component, detect and monitor the health status and the safety and reliability of in commission glass curtain wall, to the security of the lives and property that guarantees the people and to promote the development of industry such as glass deep processing all significant.

Summary of the invention

The purpose of this invention is to provide a kind of method that detects glass curtain wall loosening and prediction falling risk, at the problems referred to above, the invention provides a kind of method of utilizing vibration diagnosis principle and mechanics to combine glass curtain wall be can't harm online reliability testing technology.

The present invention detects the method for glass curtain wall loosening and prediction falling risk, adopts following steps:

1) according to the parameter of the glass plate that uses in the glass curtain wall to be measured, determines that glass is with reference to frequency range;

2) determining of safe reliability opinion rating:, survey out natural frequency corresponding under the different fixing situation, but obtain the measured frequency scope ω in the reference frequency range to the same glass plate chamber simulation test that experimentizes _Down, ω _OnWith loosening frequencies omega _PineBut respectively with two extreme value ω of measured frequency scope _On, ω _DownWith loosening frequencies omega _PineDifference as estimating classification between security interval and explosive area;

3) spot sampling test: with corresponding exciting bank and pick-up device, glass curtain wall glass is carried out vibration signal sampling and detection, obtain the practical frequency of glass curtain wall;

4) natural frequency classification practical frequency value and the step 2 that the step 3) scene is measured) compares, and according to the comparative result of data, draws the safe reliability rank of the cladding glass under this service state.

Wherein, described step 1) adopts theoretical analytical method, calculates lower limit with reference to frequency by formula (1):

${\mathrm{\ω}}^2=\frac{504\·D}{a^4\·b^4\·\stackrel{\‾}{m}}\·(a^4+b^4+\frac{4}{7}{a}^2{b}^2)---\left(1\right)$

Calculate higher limit by formula (2) with reference to frequency:

$\mathrm{\ω}={\mathrm{\π}}^2(\frac{1}{a^2}+\frac{1}{b^2})\sqrt{\frac{D}{\stackrel{\‾}{m}}}---\left(2\right)$

Wherein: the natural frequency of ω-glass, D-tested sample bending stiffness,

The glass quality of-per unit area, a-glass length, b-glass width; Wherein a and b are measured value,

Inquire about from handbook or obtain from curtain wall is installed raw data according to the tested sample material, the expression formula of bending stiffness D is:

D＝Eh ³/12(1-υ ²) (3)

Wherein: the Young modulus of E-glass material; The h-thickness of glass; The Bai Song ratio of υ-glass material.

Step 2) described evaluation is classified as inquartation: promptly loosening frequencies omega _PineAs the safe and reliable criteria line of glass curtain wall, but with the lower limit ω of measured frequency scope _DownWith ω _PineIt is two sections that the interval is divided equally, from lower limit ω _DownTo ω _PineValue corresponds to the loose or dislocation rank successively and has the hidden danger rank; With ω _PineBut higher limit ω with the measured frequency scope _OnIt is two sections that the interval is divided equally, from ω _PineBe worth higher limit ω _OnCorrespond to rank safe in utilization successively and use reliable rank.

Step 2) described evaluation is classified as another and simplifies inquartation: with reference to the lower limit ω of frequency _DownWith higher limit ω _OnDividing equally is four sections, by numerical value be divided into loose or dislocation from small to large, have hidden danger, safe in utilization and use reliable four ranks.

In the said method, but the fixed form that described theoretical value glass props up on four sides admittedly with reference to the corresponding glass of the upper limit case of frequency range and measured value measured frequency scope, the fixed form of the corresponding glass of lower limit situation four sides freely-supported.

In the said method, the evaluation criterion of described step 4) is: when the actual frequency resultant that records when the interval situation of standard security is similar, can think this cladding glass structural safety; When dropping between the explosive area, think that this structure is dangerous, recommended replacement or take measures to strengthen its structure.

Adopt technical scheme of the present invention, can a kind of convenience, simple non-destructive testing method are provided, guarantee glass product safe reliability in use for glass industry.Concerning glass enterprise and glass applications unit, can reduce the expense of production and testing cost, the quality testing of saving glass product; For building unit, a kind of method of simple and effective test cladding glass construction quality is provided, testing cost is lower, has avoided the generation of security incident; Concerning the glass user, the invention provides a kind of product that guarantees and use relieved method of testing.

Description of drawings

Fig. 1 is a principle of work synoptic diagram of the present invention;

Fig. 2 is a testing process process flow diagram of the present invention;

Fig. 3 detects the spectrogram (corresponding fundamental frequency is 370Hz) of the fastening lower glass plate in four limits in the example for the present invention;

Fig. 4 detects the spectrogram (corresponding fundamental frequency is 230Hz) of the loosening lower glass plate in four limits in the example for the present invention;

Fig. 5 detects different boundary tightness and glass fundamental frequency relation curve and safe class division in the example for the present invention.

Embodiment

The present invention at first needs to determine the fundamental frequency (minimum natural frequency) of glass curtain wall and the relation and the Damage Evolution rule of structural safety reliability.Its ultimate principle is the method by acoustic resonance or vibration measurement with laser, determines glass curtain wall Natural Frequency of Vibration under certain supporting condition.Utilize its structural reliability of relation assessment of natural frequency and stiffness of structural member.

For a large-scale military service member, the sheet glass that clamps of four sides for example, its natural frequency is subjected to its size, the influence of quality and rigidity etc.For the glass curtain wall of a known dimensions, natural frequency can think that the variation with its rigidity changes.When becoming flexible appearred in its four limits fixation case, perhaps breakage appearred in this glass curtain wall, and then its integral rigidity descends, and its natural frequency also can descend thereupon.Therefore, whether have breakage or loosening, thereby form a kind of new method of harmless on-line testing large glass member security newly if can estimate this glass curtain wall by the natural frequency that measures.The method of measuring the natural frequency of glass curtain wall has multiple, can adopt the reliability of relatively examining institute's measured frequency mutually, the present invention mainly adopts model analysis (test modal analysis and finite element analysis), phonoreception to answer vibration measuring and resonant method several method to determine natural frequency.

Below just a kind of method that detects glass curtain wall loosening and prediction falling risk of the present invention be described as follows:

The natural frequency of glass curtain wall changes along with quality, clamping degree and the damaged degree of member, so the present invention estimates this member by the natural frequency that measures whether breakage or loosening is arranged, thus the security of harmless on-line testing large glass member.Estimate the different comparisons of supporting the natural frequency of degree of tightness state lower-glass curtain walls and can adopt relative method, promptly determine the natural frequency under the four limit tightening states earlier, then the frequency that measures is compared with it, differ many more, risk probability is big more.Frequency under the different fixing state (also claiming with reference to frequency) can obtain with Theoretical Calculation or FEM (finite element) calculation; Also the frequency that the curtain wall with identical support and size and known safe can be tested is as the reference frequency.

The method that detects glass curtain wall loosening and prediction falling risk can adopt following steps (can with reference to figure 1 and Fig. 2):

1) determines with reference to frequency range: obtain the size of the glass curtain wall structure that will survey, can the raw data when installing obtain, or carry out sampled measurements, if what install is that the glass curtain wall of identical style can calculating with reference to frequency a glass.

Theoretical analytical method: the fixed form of glass curtain wall generally is divided into two kinds, and fixedly mode is propped up at four sides freely-supported fixed form and four sides admittedly.The glass that prop up under the fixing mode admittedly at the four sides is firm, and the glass under the freely-supported fixed form of four sides becomes flexible, and general service state its state of cladding glass down should be between prop up admittedly at four sides freely-supported and four sides.For simply supported on four sides and the solid rectangular thin plate fundamental vibration frequency that props up, corresponding accurate and analytical expression is arranged all in theory.

When glass curtain wall is the mode of four sides freely-supported fixedly the time, its natural frequency is calculated by formula (1), is the lower limit of reference frequency:

${\mathrm{\ω}}^2=\frac{504\·D}{a^4\·b^4\·\stackrel{\‾}{m}}\·(a^4+b^4+\frac{4}{7}{a}^2{b}^2)---\left(1\right)$

When glass is the mode at solid of four sides fixedly the time, its natural frequency is calculated by formula (2), is the higher limit of reference frequency:

$\mathrm{\ω}={\mathrm{\π}}^2(\frac{1}{a^2}+\frac{1}{b^2})\sqrt{\frac{D}{\stackrel{\‾}{m}}}---\left(2\right)$

In formula (1) and the formula (2): the natural frequency of ω-glass, D-tested sample bending stiffness,

The glass quality of-per unit area, a-glass length, b-glass width; Wherein a and b are measured value, Inquire about from handbook or obtain from curtain wall is installed raw data according to the tested sample material, the expression formula of bending stiffness D is:

D＝Eh ³/12(1-υ ²) (3)

Wherein: the Young modulus of E-glass material; The h-thickness of glass; The Bai Song ratio of υ-glass material.

Through type (1) and formula (2) are calculated, and can know numerical range that the natural frequency of glass to be detected should the place higher limit ω in the reference frequency _OnWith lower limit ω _DownBetween.

Limited element analysis technique: finite element model need obtain the correction and the checking of theoretical solution and test, finally obtains reflecting the finite element model of actual conditions.Can calculate the different supporting conditions of glass curtain wall plate and support natural frequency under the degree of tightness state by the model of revising.

2) determining of safe reliability opinion rating: can adopt test method(s) and finite element method comprehensively to determine.During test, at first the cladding glass to same size is tested in the laboratory, step 1) determine with reference to frequency range in, provide natural frequency corresponding under the different fixing situation respectively, fixation case can be divided into fastening (corresponding ω _On), loosening (corresponding ω _Pine), (corresponding ω comes off _Down) Three Estate.During finite element analysis, can calculate the different supporting conditions of glass curtain wall plate and support natural frequency under the degree of tightness state by the model of revising.According to test figure or FEM data, draw the relation of loosening situation of glass plate and natural frequency at last, set up between the natural frequency security interval and explosive area of this glass curtain wall.

Estimate stage division:

Inquartation: with simply supported on four sides and four limits prop up admittedly with reference to upper frequency limit value ω _OnWith lower limit ω _DownDifference be divided into four zones, wherein glass curtain wall can be begun loosening corresponding natural frequency ω _PineAs the safe and reliable criteria line of glass curtain wall, when practical frequency is lower than this frequency, think that there is potential safety hazard in glass curtain wall, when practical frequency is higher than this frequency, can think that this glass curtain wall is safe in utilization.Four timesharing are with ω _Down～ω _PineIt is two sections that interval frequency refinement is divided equally, and corresponding frequency separation is from ω _DownTo ω _PineDescribe the glass curtain wall user mode respectively and be loose or dislocation and exist hidden danger, loose or dislocation to think that this glass curtain wall must change or reinforce, exist potential safety hazard to think that this glass curtain wall needs reinforcement or keeps in repair.Equally, with ω _Pine～ω _OnAlso dividing equally is two intervals, from ω _PineTo ω _OnBe respectively safe in utilization and use reliably, safe in utilizationly think that this glass curtain wall user mode is good, need not keep in repair and reinforce, use and think that reliably this glass curtain wall user mode is splendid, can continue to use safely and reliably for a long time.The method of dividing frequency separation can be referring to instantiation shown in Figure 5.

Another kind of inquartation can be with reference to the higher limit ω of frequency _OnWith lower limit ω _DownDividing equally is four sections, by numerical value be divided into loose or dislocation from small to large, have hidden danger, safe in utilization and use reliable four ranks.According to experience or finite element analogy, recognize ω in this point-score _PineThe position normally at ω _OnWith lower limit ω _DownThe centre position, in order to simplify detection, can be directly with ω _On～ω _DownBe equally divided into four fens.

3) corresponding exciting bank and pick-up device are selected in spot sampling test, and glass is carried out the vibration signal sampling, and with amplifier signal are amplified back input signal treating apparatus, at last by computer software analysis, obtain the actual measurement natural frequency of glass curtain wall.

4) the practical frequency value and the step 2 that the scene are measured) the natural frequency classification compare, according to the comparative result of data, draw the safe reliability rank of the cladding glass under this service state.When the actual frequency resultant that records when the interval situation of standard security is similar, can think this cladding glass structural safety; When dropping between the explosive area, think that this structure is dangerous, recommended replacement or take measures to strengthen its structure.

The concrete implementation route of reliability evaluation technology of the present invention and glass reliability evaluation instrument and equipment workflow are as depicted in figs. 1 and 2.

Describe the present invention in detail below in conjunction with specific embodiment.

Embodiment 1: the security of laboratory simulation different boundary supported glass curtain wall structure detects

1) preliminary work of glass sample: adopt the common soda lime glass of 300 * 300 * 4mm in this test, before the test glass surface is cleaned;

2) field measurement glass size and material parameter are a=300mm, b=300mm, and h=4mm, E=70GPa (elastic modulus), v=0.24 (Poisson ratio), $\stackrel{\‾}{m}=10\mathrm{kg}/m^2.$ Calculate according to the analytical expression of formula (1) and formula (2), draw the analytic solution natural frequency value (see Table 1) of tested glass under solid and simply-supported state; Or obtain Finite-Element Solution natural frequency value (seeing Table 1) under solid and the simply-supported state according to finite element method.Can obtain tested glass frequency distribution scope by the natural frequency of calculating should be at 216～398Hz.

3) ready glass sample is placed on the square steel underframe of 280 * 280mm, the upper end covers the square frame of same size, adopts bolt in the middle of two frameworks, supports with India rubber between glass and the framework.This structure is to copy common curtain wall construction structure, and control the rigidity of total by regulating bolt elasticity between two frameworks, with the loosening situation of glass curtain wall structure in the simulated field monitoring, that simulation is classified as is fastening, hemicompact is solid, the loosening and level Four that comes off, referring to table 1.

4) regulate the elasticity of the bolt in the said structure by being tightened to pine, obtain the natural frequency of glass under different boundary degree of tightness situation, detect data and list in table 1 by dynamic test.

DLF-3 binary channels filtering integrating amplifier and INV38V intelligent signal collection Treatment Analysis instrument and supporting signal analysis software thereof that testing equipment adopts Dongfa Inst. of Vibration ﹠ Noise Technology to produce.The spectrogram of this glass under fastening situation that this test obtains seen Fig. 3, and the spectrogram under the loosening situation is seen Fig. 4; See that by spectrogram 3 natural frequency corresponding under the tightening state is 370Hz, the natural frequency that can directly read correspondence under the loosening state on Fig. 4 is 230Hz.

5) safety classification:, Fig. 5 is seen in this piece glass user mode safe class frequency partition interval according to the fixing frequency of degree of tightness correspondence in border.

Table 1 different edge part degree of tightness lower glass plate natural frequency and safe class are divided

By table 1 and Fig. 5 as can be seen, the fundamental frequency of glass plate (actual measurement natural frequency) is in and is lower than four limits and props up admittedly and be higher than between the fundamental frequency about 10% of simply supported on four sides correspondence (because the border of glass fixedly is impossible complete four limits to prop up admittedly or simply supported on four sides in the reality, so this approximately props up admittedly from four limits or the frequency separation of simply supported on four sides theoretic frequency about 10% is to record).And along with the fixation case of bolt is loose more, its fundamental frequency also decreases.It is benchmark (the corresponding fundamental frequency of this test is 300Hz) that this example experiment begins to occur loosening pairing frequency according to bolt, when the frequency that records is lower than this frequency, it is loosening to think that these glass plate four limits occur, the danger that there is potential safety hazard in this curtain wall construction or comes off.And when the frequency that records is higher than this frequency, can think that becoming flexible does not appear in these glass plate four limits, this curtain wall construction is safe and reliable.

Embodiment 2: on-the-spot glass curtain wall detects and the safe class evaluation

Engineering Notice: certain building curtain wall is bright mount structure, and glass plate is embedded in the aluminium frame, in August, 2000 completion.Understanding learns that this cladding glass is an ordinary plate glass, and the glass size size is: 1415mm * 1860mm * 6mm, glass modulus are 72GPa, and Poisson ratio is 0.24, and density is 2500kg/m ³

Evaluation criteria is divided: the analytical expression according to formula (1) and formula (2) calculates, and the frequency that obtains this curtain wall monolithic glass plate correspondence under solid and freely-supported condition is respectively 22Hz and 11.8Hz.With embodiment step 3) and 4) identical method, in testing laboratory same glass plate is tested, but obtained the measured frequency scope between 13～20Hz, loosening frequency is 15.5Hz, with loosening frequency is criteria for classifying line, this glass curtain wall user mode safe class is divided see Table 2.

Certain building cladding glass of table 2 grade frequency separation safe in utilization

Frequency separation (Hz)	13～14.5	14.5～15.5	15.5～18	18～20
					Safe class	Come off	There is hidden danger	Safe in utilization	Use reliable

Site test detects:

DLF-3 binary channels filtering integrating amplifier that employing Dongfa Inst. of Vibration ﹠ Noise Technology produces and INV38V intelligent signal collection Treatment Analysis instrument and supporting signal analysis software thereof vibrate sampling.The scene is chosen 10 blocks of representative glass and is carried out site test, and every block of glass is sampled three times, with the practical frequency of average frequency as this piece glass.Sampled result sees Table 3.

Table 3 building cladding glass sample frequency

Estimate:

Detect by on-site sampling, the natural frequency of the every glass plate of this glass curtain wall that obtains all drops on the interval of grade safe in utilization shown in the table 2, therefore thinks that this curtain wall is safe in utilization, need not reinforce and keep in repair, and can continue to use.

Claims (5)

1. one kind is detected glass curtain wall loosening and the method for predicting falling risk, adopts following steps:

1) according to the parameter of the glass plate that uses in the glass curtain wall to be measured, determines that glass is with reference to frequency range;

2) determining of safe reliability opinion rating:, survey out natural frequency corresponding under the different fixing situation, but obtain the measured frequency scope ω in the reference frequency range to the same glass plate chamber simulation test that experimentizes _Down, ω _OnWith loosening frequencies omega _PineBut respectively with two extreme value ω of measured frequency scope _On, ω _DownWith loosening frequencies omega _PineDifference as estimating classification between security interval and explosive area;

3) spot sampling test: with corresponding exciting bank and pick-up device, glass curtain wall glass is carried out vibration signal sampling and detection, obtain the practical frequency of glass curtain wall;

4) natural frequency classification practical frequency value and the step 2 that the step 3) scene is measured) compares, and according to the comparative result of data, draws the safe reliability rank of the cladding glass under this service state.

Wherein, step 1) adopts theoretical analytical method, and the fixed form of corresponding glass four sides freely-supported calculates lower limit with reference to frequency by formula (1):

The fixed form that corresponding glass is solid on four sides calculates higher limit with reference to frequency by formula (2):

Wherein: the natural frequency of ω-glass, D-tested sample bending stiffness,

The glass quality of-per unit area, a-glass length, b-glass width; Wherein a and b are measured value,

Inquire about from handbook or obtain from curtain wall is installed raw data according to the tested sample material, the expression formula of bending stiffness D is:

D＝Eh ³/12(1-υ ²) (3)

Wherein: the Young modulus of E-glass material; The h-thickness of glass; The Bai Song ratio of υ-glass material.

2. according to the described method of claim 1, it is characterized in that step 2) described evaluation is classified as inquartation: promptly loosening frequencies omega _PineAs the safe and reliable criteria line of glass curtain wall, but with the lower limit ω of measured frequency scope _DownWith ω _PineIt is two sections that the interval is divided equally, from lower limit ω _DownTo ω _PineValue corresponds to the loose or dislocation rank successively and has the hidden danger rank; With ω _PineBut higher limit ω with the measured frequency scope _OnIt is two sections that the interval is divided equally, from ω _PineBe worth higher limit ω _OnCorrespond to rank safe in utilization successively and use reliable rank.

3. according to the described method of claim 1, it is characterized in that step 2) described evaluation is classified as inquartation: with reference to the lower limit ω of frequency _DownWith higher limit ω _OnDividing equally is four sections, by numerical value be divided into loose or dislocation from small to large, have hidden danger, safe in utilization and use reliable four ranks.

4. according to the arbitrary described method of claim 1 to 3, it is characterized in that, but the solid on four sides fixed form of propping up of the corresponding glass of the upper limit case of described measured value measured frequency scope, the fixed form of the corresponding glass of lower limit situation four sides freely-supported.

5. according to the arbitrary described method of claim 1 to 3, it is characterized in that the evaluation criterion of described step 4) is: when the actual frequency resultant that records when the interval situation of standard security is similar, can think this cladding glass structural safety; When dropping between the explosive area, think that this structure is dangerous, recommended replacement or take measures to strengthen its structure.

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