ASTM E998-84(1999)
(Test Method)Standard Test Method for Structural Performance of Glass in Windows, Curtain Walls, and Doors Under the Influence of Uniform Static Loads by Nondestructive Method
Standard Test Method for Structural Performance of Glass in Windows, Curtain Walls, and Doors Under the Influence of Uniform Static Loads by Nondestructive Method
SCOPE
1.1 This test method is a nondestructive test procedure to establish the nature of stresses induced in glass in windows, curtain walls, and doors subjected to uniform static loads. A procedure is provided for using this stress information to estimate the probability of failure of the glass.
1.2 This test method is applicable to glass of various degrees of temper; for example, annealed, heat-strengthened, fully tempered, laminated, insulated, and combinations thereof.
1.3 This test method describes a process of applying specific test loads to glass. The test may be conducted using the standard test frame specified herein or a test frame of the user's design.
1.4 The values stated in inch-pound units are to be regarded as standard.
1.5 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements see Section 6.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
An American National Standard
Designation: E 998 – 84 (Reapproved 1999)
Standard Test Method for
Structural Performance of Glass in Windows, Curtain Walls,
and Doors Under the Influence of Uniform Static Loads by
Nondestructive Method
This standard is issued under the fixed designation E998; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2.4 equivalent design load—a magnitude of a 60-s duration
uniform load selected by specifying authority to represent
1.1 This test method is a nondestructive test procedure to
design loads.
establish the nature of stresses induced in glass in windows,
2.5 glass specimen—the glass to be tested, for example, a
curtain walls, and doors subjected to uniform static loads. A
singlepane,aninsulatingglassunit,laminatedglass,etc.(does
procedure is provided for using this stress information to
not include test frame).
estimate the probability of failure of the glass.
2.6 maximum principal tensile stress (MPTS)—amaximum
1.2 This test method is applicable to glass of various
calculated tensile stress based on strain gage measurements.
degrees of temper; for example, annealed, heat-strengthened,
2.7 negative load—aloadthatresultsintheindoorsideofa
fullytempered,laminated,insulated,andcombinationsthereof.
glass specimen being the high-pressure side.
1.3 Thistestmethoddescribesaprocessofapplyingspecific
2.8 permanent set of test frame—a load-induced permanent
test loads to glass. The test may be conducted using the
displacement from an original position of the test frame.
standardtestframespecifiedhereinoratestframeoftheuser’s
2.9 positive load—a load that results in the outdoor side of
design.
a glass specimen being the high-pressure side.
1.4 The values stated in inch-pound units are to be regarded
2.10 probability of failure—the probability that a glass
as standard.
specimen fails when tested at a given equivalent design load.
1.5 This standard does not purport to address all of the
General industry practice to express probability as lights per
safety problems, if any, associated with its use. It is the
1000 lights.
responsibility of the user of this standard to establish appro-
2.11 residual stress—an initial, state of stress on unloaded,
priate safety and health practices and determine the applica-
unglazed glass resulting from manufacturing process (heat-
bility of regulatory limitations prior to use. For specific
strenthening, tempering).
precautionary statements see Section 6.
2.12 specifying authority—the professional or professionals
2. Terminology responsible for determining and furnishing the information
required to perform this test method as described in Section 9.
2.1 aspect ratio—a ratio of long side to short side of glass
plate.
3. Summary of Test Method
2.2 average breaking stress (ABS)—the average maximum
3.1 This test method consists of:
principal tensile stress (MPTS) at failure, representative of the
3.1.1 Glazing the test specimen into a test frame that is
glass under test.TheABS is dependent on a number of factors
mounted on or against a test chamber.
includinggeometry,timehistoryofload,surfacecondition,etc.
3.1.2 Supplyingorexhaustingairfromthechamberatarate
Glasses with residual surface stresses, such as heat-
required to maintain test-pressure difference across the test
strengthened or fully tempered, must have their residual
specimen.
stresses added to the state of stress at the specified load. As
3.1.3 Measuring and observing deflections, deformations,
defined for use in the standard, theABS is for annealed glass.
specimen strains, and the nature of any failures.
2.3 coeffıcient of variation—the ratio (decimal fraction) of
3.1.4 Recording the results in an orderly manner.
the standard deviation of the maximum principal tensile stress
3.2 Methods of loading to nondestructive levels are pro-
(MPTS) at failure to the ABS.
vided.
3.3 Test data are used to predict glass structural perfor-
This test method is under the jurisdiction of ASTM Committee E-6 on mance characteristics.
Performance of Buildings and is the direct responsibility of Subcommittee E06.51
on Component Performance of Windows, Curtain Walls, and Doors.
Current edition approved June 28, 1984. Published September 1984.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E 998 – 84 (1999)
4. Significance and Use 5.2.7 Temperature Measuring Apparatus, to measure the
ambient temperature within an accuracy of 61°F (0.6°C).
4.1 This test method is a standard procedure to determine a
5.2.8 Relative Humidity Measuring Apparatus, to measure
stress pattern and estimate a probability of failure of glass
the relative humidity within an accuracy of 62%.
tested under uniform static loads.
4.2 Loads on glass in windows, curtain walls, and doors
6. Safety Precautions
may vary greatly in magnitude, direction, and duration. An
6.1 Proper precautions to protect observers in the event of
understanding of wind loads on the building is desirable for
glass specimen failure should be observed. At the pressures
selection of test loads and interpretation of results with respect
used in this test method, considerable energy and hazard are
to expected exposure at a particular site.
involved. In cases of failure, the hazard to personnel is less
4.3 The strength of glass varies with many different factors
with an exhaust system, as the specimen will tend to blow into
including surface condition, load duration, geometry, relative
2 rather than out of the test chamber. No personnel should be
humidity, and temperature (1, 2, 3, 4).
permitted in such chambers during tests. All reasonable pre-
4.4 A thorough understanding of the variations of the
cautions should be exercised during conduct of the test.
strength of glass and the nature of loading is required to
interpret results of this test method.
7. Sampling and Glass Specimens
4.5 Theproperuseofthistestmethodrequiresaknowledge
7.1 Surface condition, cutting, fabrication and packaging of
of the principles of pressure, deflection and strain measure-
the glass specimens to be tested shall be representative of the
ment,stress/strainrelationships,andstatisticalestimatingtech-
glass whose strength is to be evaluated.
niques.
7.2 All glass specimens shall be visually inspected for edge
or surface irregularities prior to testing, and all questionable
5. Apparatus
glass specimens shall not be tested. All questionable glass
5.1 The description of apparatus is general in nature. Any
specimens shall be reported to the specifying authority.
equipment capable of performing the test procedure within the
7.3 Glass specimens shall be handled carefully at all times
allowable tolerances is permitted.
because the strength of glass is influenced by its surface and
5.2 Major Components:
edge conditions.
5.2.1 Test Frame,inwhichglassspecimensaremountedfor
testing. The test frame shall provide either standardized sup-
8. Calibration
port conditions or specified support conditions. Specifications
8.1 Pressure-measuring systems, deflection-measuring de-
of standardized support conditions are presented inAnnexA1.
vices, and strain gages should be routinely checked. If calibra-
5.2.2 Test Chamber, sealed, with an opening in which or
tion is required, the manufacturer’s recommendations or good
against which the test frame is installed. At least one static
engineering practice shall be followed.
pressure tap shall be provided to measure the test chamber
pressure and shall be so located that the reading is minimally
9. Required Information
affected by the velocity of the air supply to or from the test
9.1 The specifying authority shall provide the magnitude of
chamber or any other air movement. The air supply opening
the equivalent design load (positive or negative) and the
into the test chamber shall be arranged so that the air does not
allowable probability of failure for the glass specimens.
impinge directly on the glass specimen with any significant
9.2 The specifying authority shall state whether the glass
velocity. A means of access into the test chamber may be
specimens shall be glazed in a standard test frame or in a test
provided to facilitate adjustments and observations after the
framedesignedtosimulateaspecificglazingsystem.Ifthetest
specimen has been installed.
frame is to simulate a specific glazing system, complete
5.2.3 Air System, a controllable blower, compressed air
glazing details and support conditions shall be provided by the
supply, exhaust system, reversible blower or other device
specifying authority.
designed to apply the equivalent design load to the glass
specimen with required control.
10. Procedure
5.2.4 Pressure Measuring Apparatus, to record continu-
10.1 Measure and record ambient temperature and the
ously the test chamber pressure within an accuracy of 62%.
relative humidity.
5.2.5 Deflection-Measuring System, for measuring deflec-
10.2 Installstraingagestothelowpressuresideoftheglass
tions within an accuracy of 60.01 in. (0.25 mm).
specimen according to procedures in Annex A2.
5.2.5.1 The deflection indicator shall be mounted so that
10.3 Install glass specimens in the test frame in accordance
deflection of the test chamber or test frame is not included in
with recommendations in Annex A1 for standard support
thedeflectiongagereading.Provisionsshallbemadetoensure
conditions or as specified for a specific glazing system.
that readings can be made from a safe location.
10.4 Record reference strain reading at no-load conditions.
5.2.6 Strain Gage Measurements—Appendix X1 describes
10.5 Load specimen to low level pressure, 20% of design
apparatus and techniques required for proper strain measure-
load for 1 min. Release load. Allow 3 to 5-min gage and
ments on glass.
restoration time.
10.6 Apply one half of the design load to the glass speci-
men. Take initial set of pressure, deflection, and strains at one
The boldface numbers in parentheses refer to the references listed at the end of
this test method. half of design load. Reduce the test pressure to 0, and vent the
E 998 – 84 (1999)
test chamber for a period of 3 to 5 min before pressure- performance of the glass. For new glass, the ABS should be
measuring apparatus is adjusted to zero. obtained from the appropriate glass manufacturer for the glass
10.6.1 If air leakage around the test specimen is excessive, in question. For glass that have been in service, or treated by
tapemaybeusedtocoveranycracksandjointsthroughwhich others (weathered, altered, damaged, scratched, or mechani-
the leakage is occurring. Tape shall not be used when there is cally altered) engineering judgement should be used or a glass
a probability that it may significantly restrict differential technologist consulted to determine the ABS. The area of the
movement between the glass and test frame. glass light and the duration of imposed load affect the ABS.
10.7 Apply load to the glass specimen in increments of The magnitude of the load duration effect can be roughly
20% of design load, recording strain gage readings at each approximated by using Eq X1.1 in Appendix X1.
increment. Maintain the load at each increment of design load 12.3 Probability of Failure—Once glass ABS is established
untilallstraingagereadingsaretaken.Foreachincrement,the
(Procedure A), the normal probability distribution function is
load should not be applied for a period under 1 min or longer used to predict probability of failure.The probability of failure
than 5 min in duration. Continuous load-time records shall be
for glass is calculated as follows:
kept for the duration of the loading.
Area 5 Pr~Z$ z ! (1)
o
10.8 If specimen fails prior to design load, check for
X 2 ABS
permanent set of test frame and chamber damage.Test another
Z 5
o
CV 3 ABS
gaged specimen if necessary.
where:
11. Report
X = maximumglasstensionstressresultingfromspeci-
11.1 The report shall include the following information:
fied or test wind load, psi (MPa),
11.1.1 Date of the test, the date of the report, the ambient
ABS = glass ABS, psi, (MPa),
temperature, and the relative humidity. CV = coefficient of variation, 0.22 for annealed glass,
11.1.2 Identification of the glass specimens (manufacturer, and
Z = standard normal variable (see Table X1.2).
source of supply, dimensions, both nominal and measured,
o
manufacturer’s designation, materials, and other pertinent
Using the standard normal distribution table, the area to the
information). right of the Z indicates the probability of failure at that level
o
11.1.3 Detailed drawings of the glass specimen, test frame,
(see Table X1.2).
test chamber, a complete description of pressure-measuring
NOTE 1—Glasses with residual surface stresses, such as heat-
apparatus, all other instrumentation, and a statement that the
strengthened or fully tempered, must have their residual stresses added to
test was conducted using a standard test frame or a test frame
the state of stress at the specified load. For example, the state of stress of
of the user’s design.
a heat-strengthened glass surface is 5000 psi (35 MPa) at design load, if
11.1.4 Records of pressure differences exerted across each theglasshasaresidualcompressivestressonthesurfaceof−3500psi(24
MPa), the resulting tensile stress component is 1500 psi (10 MPa) at
glass specimen during the test with each specimen being
design load.
properly identified.
NOTE 2—Load/stress relationships for large deflections in glass may be
11.1.5 Probability of failure (Z ) as calculated in Section 12
o
adequately defined by finite-element computer techniques. The values
(Analysis).
obtainedbythistechniquewillbeusefulfordefiningprobabilityoffailure
11.1.6 Identification or description of any applicable speci-
estimates at various load/glass stress combinations.
fication.
11.1.7 A statement that the tests were conducted in accor-
13. Precision and Bias
dance with this test method, or a full description of any
13.1 No statement is made about either the precision or the
deviations.
bias of this test method for measuring the structural perfor-
mance of glass since the result merely states whether the
12. Analysis
probability of failure of the glass specimens is significantly
12.1 An analysis of the structural performance of the glass
greater than the specified probability of failure or not.
specimen(s) shall be made.
12.2 Procedure A:
14. Keywords
12.2.1 Calculate maximum principal stress from strain gage
data (see Appendix X1). 14.1 curtainwalls;doors;glassperformance;nondestru
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.