1、Designation: E 998 05Standard Test Method forStructural Performance of Glass in Windows, Curtain Walls,and Doors Under the Influence of Uniform Static Loads byNondestructive Method1This standard is issued under the fixed designation E 998; the number immediately following the designation indicates t
2、he year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method is a nondestructive test proced
3、ure toestablish the nature of stresses induced in glass subjected touniform static loads. A procedure is provided for using thisstress information to estimate the probability of breakage of theglass.1.2 This test method is applicable to glass of variousdegrees of temper; for example, annealed, heat-
4、strengthened,fully tempered, laminated, insulating, and combinationsthereof.1.3 This test method describes a process of applying specifictest loads to glass. The test may be conducted using thestandard test frame specified herein or a test frame of the usersdesign.1.4 The values stated in SI units a
5、re to be regarded as thestandard. The values given in parentheses are for informationonly.1.5 This standard does not purport to address all of thesafety problems, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practic
6、es and determine the applica-bility of regulatory limitations prior to use. For specificprecautionary statements see Section 6.2. Terminology2.1 aspect ratioa ratio of long side to short side of theglass lite.2.2 average breaking stress (ABS)the average maximumprincipal tensile stress (MPTS) at fail
7、ure, representative of theglass under test. The ABS is dependent on a number of factorsincluding geometry, time history of load, surface condition,and so forth. Glasses with residual surface stresses, such asheat-strengthened or fully tempered, must have their residualstresses added to the state of
8、stress at the specified load. Asdefined for use in the standard, the ABS is for annealed glass.2.3 coeffcient of variationthe ratio (decimal fraction) ofthe standard deviation of the maximum principal tensile stress(MPTS) at failure to the ABS.2.4 equivalent design loada magnitude of a uniform loada
9、nd the load duration selected by the specifying authority torepresent design loads.2.5 glass specimenthe glass to be tested, for example, asingle lite, an insulating glass unit, laminated glass, and soforth (does not include test frame).2.6 maximum principal tensile stress (MPTS) a maximumcalculated
10、 tensile stress based on strain gage measurements.2.7 negative loada load that results in the indoor side of aglass specimen being the high-pressure side.2.8 permanent set of test framea load-induced permanentdisplacement from an original position of the test frame.2.9 positive loada load that resul
11、ts in the outdoor side ofa glass specimen being the high-pressure side.2.10 probability of breakagethe probability that a glassspecimen breaks when tested at a given equivalent design load.General industry practice to express probability as lites per1000 lites.2.11 residual stressan initial, state o
12、f stress on unloaded,unglazed glass resulting from the manufacturing process (heat-strengthening, tempering).2.12 specifying authoritythe professional or professionalsresponsible for determining and furnishing the informationrequired to perform this test method as described in Section 9.3. Summary o
13、f Test Method3.1 This test method consists of:3.1.1 Glazing the test specimen into a test frame that ismounted on or against a test chamber.3.1.2 Supplying or exhausting air from the chamber at a raterequired to maintain a test-pressure difference across the testspecimen.3.1.3 Measuring and observin
14、g deflections, deformations,specimen strains, and the nature of any failures.3.1.4 Recording the results in an orderly manner.1This test method is under the jurisdiction of ASTM Committee E06 onPerformance of Buildings and is the direct responsibility of Subcommittee E06.51on Component Performance o
15、f Windows, Curtain Walls, and Doors.Current edition approved Oct. 1, 2005. Published November 2005. Originallyapproved in 1984. Last previous edition approved in 1999 as E 998 84 (1999).1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States
16、.3.2 Methods of loading to nondestructive levels are pro-vided.3.3 Test data are used to predict glass structural perfor-mance characteristics.4. Significance and Use4.1 This test method is a standard procedure to determine astress pattern and estimate a probability of breakage of glasstested under
17、uniform static loads.4.2 Loads on glass in windows, curtain walls, and doorsmay vary greatly in magnitude, direction, and duration. Anunderstanding of wind loads on the building is required forselection of test loads and interpretation of results with respectto expected exposure at a particular site
18、.4.3 The strength of glass varies with many different factorsincluding surface condition, load duration, geometry, relativehumidity, and temperature (1, 2, 3, 4).24.4 A thorough understanding of the variations of thestrength of glass and the nature of loading is required tointerpret results of this
19、test method.4.5 The proper use of this test method requires a knowledgeof the principles of pressure, deflection and strain measure-ment, stress/strain relationships, and statistical estimating tech-niques.5. Apparatus5.1 The description of apparatus is general in nature. Anyequipment capable of per
20、forming the test procedure within theallowable tolerances shall be permitted.5.2 Major Components:5.2.1 Test Frame, in which glass specimens are mounted fortesting. The test frame shall provide either standardized sup-port conditions or specified support conditions. Specificationsof standardized sup
21、port conditions are presented in Annex A1.5.2.2 Test Chamber, sealed, with an opening in which oragainst which the test frame shall be installed. At least onestatic pressure tap shall be provided to measure the testchamber pressure and shall be so located that the reading isminimally affected by the
22、 velocity of the air supply to or fromthe test chamber or any other air movement. The air supplyopening into the test chamber shall be arranged so that the airdoes not impinge directly on the glass specimen with anysignificant velocity. A means of access into the test chambershall be permitted to fa
23、cilitate adjustments and observationsafter the specimen has been installed.5.2.3 Air System, a controllable blower, compressed airsupply, exhaust system, reversible blower or other devicedesigned to apply the equivalent design load to the glassspecimen with required control.5.2.4 Pressure Measuring
24、Apparatus, to record continu-ously the test chamber pressure within an accuracy of 62%.5.2.5 Deflection-Measuring System, for measuring deflec-tions within an accuracy of 60.25 mm (0.01 in.).5.2.5.1 The deflection indicator shall be mounted so thatdeflection of the test chamber or test frame is not
25、included inthe deflection gage reading. Provisions shall be made to ensurethat readings can be made from a safe location.5.2.6 Strain Gage MeasurementsAppendix X1 describesapparatus and techniques required for proper strain measure-ments on glass.5.2.7 Temperature Measuring Apparatus, to measure the
26、ambient temperature within an accuracy of 60.6C (1F).5.2.8 Relative Humidity Measuring Apparatus, to measurethe relative humidity within an accuracy of 62%.6. Safety Precautions6.1 Proper precautions to protect observers in the event ofglass specimen failure shall be observed. At the pressures usedi
27、n this test method, considerable energy and hazard areinvolved. In cases of breakage, the hazard to personnel is lesswith an exhaust system, as the specimen will tend to blow intorather than out of the test chamber. No personnel shall bepermitted in such chambers during tests. All reasonable pre-cau
28、tions shall be exercised during conduct of the test.7. Sampling and Glass Specimens7.1 Surface condition, cutting, fabrication and packaging ofthe glass specimens to be tested shall be representative of theglass whose strength is to be evaluated.7.2 All glass specimens shall be visually inspected fo
29、r edgeor surface irregularities prior to testing, and all questionableglass specimens shall not be tested. All questionable glassspecimens shall be reported to the specifying authority.7.3 Glass specimens shall be handled carefully at all timesbecause the strength of glass is influenced by its surfa
30、ce andedge conditions.8. Calibration8.1 Pressure-measuring systems, deflection-measuring de-vices, and strain gages shall be routinely checked. If calibrationis required, the manufacturers recommendations or goodengineering practice shall be followed.9. Required Information9.1 The specifying authori
31、ty shall provide the magnitude ofthe equivalent design load (positive or negative) and theallowable probability of breakage for the glass specimens.9.2 The specifying authority shall state whether the glassspecimens shall be glazed in a standard test frame or in a testframe designed to simulate a sp
32、ecific glazing system. If the testframe is to simulate a specific glazing system, completeglazing details and support conditions shall be provided by thespecifying authority.10. Procedure10.1 Measure and record ambient temperature and therelative humidity.10.2 Install strain gages to the low pressur
33、e side of the glassspecimen according to procedures in Annex A2.10.3 Install glass specimens in the test frame in accordancewith recommendations in Annex A1 for standard supportconditions or as specified for a specific glazing system by themanufacturer.10.4 Record reference strain reading at no-load
34、 conditions.2The boldface numbers in parentheses refer to the references listed at the end ofthis test method.E99805210.5 Load specimen to low level pressure, 20 % of designload for 1 min. Release load. Allow 3 to 5-min gage andrestoration time.10.6 Apply one-half of the specified design load to the
35、 glassspecimen. Take initial set of pressure, deflection, and strainreadings at one-half of design load. Reduce the test pressure to0, and vent the test chamber for a period of 3 to 5 min beforepressure-measuring apparatus is adjusted to zero.10.6.1 If air leakage around the test specimen is excessi
36、ve,tape shall be permitted to be used to cover any cracks and jointsthrough which the leakage is occurring. Tape shall not be usedwhen there is a probability that it may significantly restrictdifferential movement between the glass and test frame.10.7 Apply load to the glass specimen in increments o
37、f20 % of specified design load, recording strain gage readings ateach increment. Maintain the load at each increment of designload until all strain gage readings are taken. For each incre-ment, the load should not be applied for a period under 1 minor longer than 5 min in duration. Continuous load-t
38、ime recordsshall be kept for the duration of the loading.10.8 If the specimen breaks prior to reaching the specifieddesign load, check for permanent set of the test frame andchamber damage before testing another specimen.11. Report11.1 The report shall include the following information:11.1.1 Date o
39、f the test, the date of the report, the ambienttemperature, and the relative humidity.11.1.2 Identification of the glass specimens (manufacturer,source of supply, dimensions, both nominal and measured,manufacturers designation, materials, and other pertinentinformation).11.1.3 Detailed drawings of t
40、he glass specimen, test frame,test chamber, a complete description of pressure-measuringapparatus, all other instrumentation, and a statement that thetest was conducted using a standard test frame or a test frameof the users design.11.1.4 Records of pressure differences exerted across eachglass spec
41、imen during the test with each specimen beingproperly identified.11.1.5 Probability of breakage (Zo) as calculated in Section12 (Analysis).11.1.6 Identification or description of any applicable speci-fication.11.1.7 A statement that the tests were conducted in accor-dance with this test method, or a
42、 full description of anydeviations.12. Analysis12.1 An analysis of the structural performance of the glassspecimen(s) shall be made.12.2 Procedure A:12.2.1 Calculate maximum principal stress from strain gagedata (see Appendix X1).12.2.2 Average Breaking Strength of Glass (ABS)TheABS is a necessary v
43、alue for use in analyzing the structuralperformance of the glass. For new glass, the ABS shall beobtained from the appropriate glass manufacturer for the glassin question. For glass that has been in service, or treated byothers (weathered, altered, damaged, scratched, or mechani-cally altered) engin
44、eering judgement shall be used to determinetheABS. The area of the glass lite and the duration of imposedload affect the ABS. The magnitude of the load duration effectcan be roughly approximated by using Eq X1.1 in AppendixX1.12.3 Probability of BreakageOnce glass ABS is estab-lished (Procedure A),
45、the normal probability distribution func-tion is used to predict probability of breakage. The probabilityof breakage for glass is calculated as follows:Area 5 PrZ$zo! (1)Zo5X 2 ABSCV 3 ABSwhere:X = maximum glass tension stress resulting from speci-fied or test wind load, MPa (psi),ABS = glass ABS, M
46、Pa (psi),CV = coefficient of variation, 0.22 for annealed glass,andZo= standard normal variable (see Table X1.2).Using the standard normal distribution table, the area to theright of the Zoindicates the probability of breakage at that level(see Table X1.2).NOTE 1Glasses with residual surface stresse
47、s, such as heat-strengthened or fully tempered, shall have their residual stresses added tothe state of stress at the specified load. For example, the state of stress ofa heat-strengthened glass surface is 35 MPa (5000 psi) at design load, ifthe glass has a residual compressive stress on the surface
48、 of 24 MPa(3500 psi), the resulting tensile stress component is 10 MPa (1500 psi)at design load.NOTE 2Load/stress relationships for large deflections in glass may beadequately defined by finite-element computer techniques. The valuesobtained by this technique will be useful for defining probability
49、ofbreakage estimates at various load/glass stress combinations.13. Precision and Bias13.1 No statement is made about either the precision or thebias of this test method for measuring the structural perfor-mance of glass since the result merely states whether theprobability of breakage of the glass specimens is significantlygreater than the specified probability of breakage or not.14. Keywords14.1 annealed glass; curtain walls; doors; flat glass; fullytempered glass; glass performance; heat-strenghtened glass;nondestructive testing; performance testing; strain g
