ASTM E2431-06(2011)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:E2431–06 (Reapproved 2011)
Standard Practice for
Determining the Resistance of Single Glazed Annealed
Architectural Flat Glass to Thermal Loadings
This standard is issued under the fixed designation E2431; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This practice covers a procedure to determine the 2.1 ASTM Documents:
resistance of annealed architectural flat glass to thermally C162 Terminology of Glass and Glass Products
induced stresses caused by exposure to sun and shadows for a E631 Terminology of Building Constructions
specified probability of breakage (P ). Proper use of this IEEE/ASTMSI-10 UseoftheInternationalSystemofUnits
b
procedure is intended to reduce the possibility of thermal (SI) (the Modernized Metric System)
breakage of annealed glass in buildings. 2.2 Other Documents:
1.2 This practice applies to vertical or sloped glazing in 2005 ASHRAE Handbook Fundamentals
buildings.
3. Terminology
1.3 This practice applies to monolithic and laminated glass
3.1 Definitions:
of rectangular shape and assumes that all glass edges are
simply supported. 3.1.1 Refer to Terminologies C162 and E631 for additional
terms used in this practice
1.4 This practice applies only to annealed flat soda-lime
silica glass with clean cut, seamed, flat ground, or ground and 3.2 Definitions of Terms Specific to This Standard:
3.2.1 edge bite, n—the width of the glass edge (measured
polished edges that are free from damage. The glass may be
clear or tinted as well as coated (not including coatings that perpendicular to the cut edge, in the plane of the glass) that is
protected from direct exposure to solar irradiance by the
reduce emissivity of the glass).
1.5 This practice does not apply to any form of wired, window frame edge conditions expressed in mm (in.) [see
Table 1].
patterned, etched, sandblasted, drilled, notched, or grooved
3.2.2 edge thermal stress factor (TSF ), n—the ratio of
glass or glass with surface and edge treatments, other than
edge
those described in 1.4, that alter the glass strength. induced thermal stress to the solar load, SL, as the result of the
edge bite condition expressed in MPa/(W/m ).
1.6 This practice does not address uniform loads such as
wind and snow loads, safety requirements, fire, or impact 3.2.3 frame type, n—the manner in which the edges of the
glass are supported in the window frame [see Table 1].
resistance.
1.7 The values stated in SI units are to be regarded as 3.2.4 glass dimensions, n—the rectangular dimensions of
the glass (not the daylight opening), with the width being the
standard. The values given in parentheses are mathematical
conversions to inch-pound units that are provided for informa- smaller dimension and the length being the larger dimension
both expressed in mm.
tion only and are not considered standard. For conversion of
quantities in various systems of measurements to SI units refer 3.2.5 incident solar irradiance (Insolation), (I ), n—amount
s
of solar energy per unit time per unit area normal to glass, to
to IEEE/ASTM SI-10.
1.8 This standard does not purport to address all of the which the glass is exposed expressed in W/m .
3.2.6 probability of breakage (P ), n—the number of lites
safety concerns, if any, associated with its use. It is the
b
responsibility of the user of this standard to establish appro- per 1000 that would be predicted to break when exposed to the
specified thermal loading conditions.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This practice is under the jurisdiction of ASTM Committee E06 on Perfor- contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
mance of Buildings and is the direct responsibility of Subcommittee E06.51 on Standards volume information, refer to the standard’s Document Summary page on
Performance of Windows, Doors, Skylights and Curtain Walls. the ASTM website.
Available from American Society of Heating, Refrigerating, and Air-
Current edition approved Oct. 1, 2011. Published October 2011. Originally
approved in 2006. Last previous edition approved in 2006 as E2431 – 06. DOI: Conditioning Engineers, Inc. (ASHRAE), 1791 Tullie Circle, NE, Atlanta, GA
10.1520/E2431-06R11. 30329, http://www.ashrae.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E2431–06 (2011)
TABLE 1 Frame Types
Frame Type Sketch
Insulated edge -- This condition should only be used in the analysis if it can
reasonably be assumed that the heat loss from the glass to the glazing
pocket is negligible.
Conventional edge -- This condition should be used in the analysis only when
the glazing pocket is fabricated with thin walled members and the glass is
cushioned with gasket materials as shown.
High heat mass edge -- This condition should be used in the analysis when the
glazing is encapsulated in a material with a high heat mass such as concrete,
heavy metal, and so forth.
3.2.7 shadow thermal stress factor (TSF ), n—the ratio 3.2.9 solar load adjustment factor for interior shading
shadow
of induced thermal stress to the solar load, SL, as the result of
devices (SLA), n—nondimensional factor that is used to
2 2
shadow condition expressed in MPa/(W/m ) (psi/Btu/hr·ft ).
account for the increase in thermal stress caused by the
3.2.8 solar load (SL), n—the total amount of solar irradi-
reflection of solar irradiance from an interior shading device.
ance absorbed by the glass expressed in W/m .
E2431–06 (2011)
TABLE 2 Shadow Thermal Stress Factors to be Used with Fig. 2
5.3 Many other factors shall be considered in glass selec-
Shadow Condition Maximum TSF tion.These factors include, but are not limited to, mechanically
shadow
kPa/(W/sq m)
induced stresses, wind effects, windborne debris impacts,
Linear shadow 15.3
excessive deflections, seismic effects, heat flow, noise abate-
Angular shadow 31.9
ment, potential post-breakage consequences, and so forth. In
L-Shaped shadow 20.8
addition, considerations set forth in building codes along with
Corner shadow 23.0
criteria presented in safety glazing standards and site specific
concerns may control the ultimate glass type and thickness
selection.
3.2.10 solar reflectance of shading device (R ), n—decimal
s
5.4 The proper use of this practice is intended to reduce the
fraction of incident solar irradiation reflected from the device
risk of thermally induced breakage of annealed window glass
used as an interior shade.
in buildings.
3.2.11 solar transmittance (T ), n—the amount of solar
s
irradiance transmitted by the glass expressed as a fraction that 6. Procedure
ranges between 0.00 and 1.00.
6.1 Obtain the following information from the data supplied
3.2.12 thermal stress, n—edge tensile stress (MPa) induced
by the specifier:
in glass by solar irradiance.
6.1.1 The edge bite condition that most closely represents
3.2.13 total solar absorptance (A ), n—the amount of solar
s
the project conditions from Table 1;
irradiance absorbed by the glass expressed as a fraction that
6.1.2 The total solar transmittance (T ) of the specified
s
ranges between 0.00 and 1.00.
glass;
3.2.14 total thermal stress factor (TSF ), n—the ratio of
tot
6.1.3 The total solar absorptance (A ) of the specified glass:
s
total thermal stress induced in the glass by the combination of
A 51.002T 2 R (1)
s s s
edge conditions and shadow conditions to the solar load
expressed in MPa/(W/m ).
where:
R = total solar reflectance
s
4. Summary of Practice
6.1.4 The solar reflectance of the shading device (RSD), if
4.1 The specifying authority shall provide the glass width, used;
6.1.5 The incident solar irradiance (I ) for this analysis; and
length, and nominal thickness; solar absorption of the glass
s
construction (can be obtained from manufacturer’s data); 6.1.6 The specified acceptable probability of glass breakage
(P ) for this analysis.
incident solar irradiance (can be determined from 2005
b
ASHRAE Handbook Fundamentals or other documented 6.2 Multiply the incident solar irradiance (I ) by the solar
s
absorptance (A ) to determine the solar load (SL).
source); the frame type and edge bite; description of exterior
S
shading conditions; and interior shading devices. 6.3 Determine the edge thermal stress factor (TSF ) from
edge
Fig. 1, given the edge bite and edge bite condition.
4.2 The procedure described in this practice shall be used to
determine if the glass can resist the calculated thermal stresses 6.4 Determine the shadow thermal stress factor (TSF )
shadow
using the common shadow patterns shown in Fig. 2 and the
for a specified probability of breakage.
factors listed in Table 2.
5. Significance and Use 6.5 Determine the total thermal stress factor (TSF )by
total
summing the individual thermal stress factors given in 6.3 and
5.1 Use of this practice assumes:
6.4.
5.1.1 the glass edges shall be free from damage,
6.5.1 If the calculated total thermal stress factor exceeds
5.1.2 the glass shall be properly glazed,
39.4 kPa/(W/m ) when the angular shadow pattern is assumed,
5.1.3 the glass shall not have been subjected to abuse, and
that is, Fig. 2 b and d, then 39.4 kPa/(W/m ) shall be used for
5.1.4 the glass edge support allows in-plane movement of
the total thermal stress factor.
the glass due to thermal expansion and contraction.
6.5.2 If the calculated total thermal stress factor exceeds
5.2 This practice does not address all factors that cause
32.0 kPa/(W/m ) when other shadow patterns, that is, Fig. 2 a
thermally induced stresses in annealed glass. Factors that are
and c, are assumed, then 32.0 kPa/(W/m ) shall be used for the
not addressed include: transient thermal stresses, HVAC reg-
total thermal stress factor.
isters, thermally insulating window coverings, drop ceilings
6.6 To determine the solar load adjustment factor (SLA)
and other heat traps, increased solar irradiance caused by
using Fig. 3, enter the vertical axis with the solar reflectance of
exteriorreflections,variationsinheattransfercoefficientsother
the shading device (RSD) and the horizontal axis with total
than those assumed for the steady state analysis described
solar transmittance of the glass (T ) to determine the solar load
herein, and stresses induced by thermal sources other than the S
adjustment factor (SLA) for interior shading devices. If nec-
sun. Factors other than those listed above may also induce
essary use interpolation to estimate the solar load adjustment
thermal stress.
factor (SLA). If no shading device is used, the solar load
adjustment factor (SLA) shall be taken to be 1.0.
6.7 Determine the calculated thermal stress, s ,by
4 calculated
Beason, W.L., and Lingnell,A.W., “AThermal Stress Evaluation Procedure for
multiplyingthetotalthermalstressfactor(TSF )bythesolar
Monolithic Annealed Glass,” Use of Glass in Buildings, ASTM STP 1434, V. total
Block, ed., ASTM International: West Conshohocken, PA, 2003. load (SL) and by the solar load adjustment factor (SLA).
E2431–06 (2011)
FIG. 1 Edge Thermal Stress Factor Chart
6.8 Determinetheperimeteroftheglasslitebyaddingtwice 7.1.4 Glass type,
the width to twice the height.
7.1.5 Glass dimensions,
6.9 Determine the allowable thermal stress, s , from
7.1.6 Edge bite,
allowable
Fig.4usingtheglassperimeterandthespecifiedacceptable P .
7.1.7 Frame type,
b
6.10 If s > s , P for the glass exceeds the
calculated allowable b 7.1.8 Solar absorptance (A ),
s
specified probability of breakage for the thermal design con-
7.1.9 Solar transmittance (T ),
s
ditions. If P for the glass exceeds the specified probability of
b
7.1.10 Total Solar Reflectance of Shade Device (RSD),
breakage, the user shall consider using strengthened glass,
7.1.11 Incident solar irradiance (I ),
s
modifying the controllable design conditions, or having a more
7.1.12 Acceptable probability of breakage (P ),
b
comprehensive thermal stress analysis performed.
7.1.13 Allowable thermal stress (s ),
allowable
7.1.14 Calculated thermal stress (s ), and
7. Report calculated
7.1.15 Conclusion.
7.1 The report shall consist of the design example work-
sheet presented in Fig. 5 or, as a minimum, shall include:
8. Keywords
7.1.1 Project name,
7.1.2 Date, 8.1 annealed glass; flat glass; glass; thermal breakage;
7.1.3 Project location, thermal load; thermal stress; soda-lime silica glass
E2431–06 (2011)
FIG. 2 Shadow Conditions
E2431–06 (2011)
FIG. 3 Solar Load Adjustment Factor, SLA
FIG. 4 Probability of Breakage (POB) Chart
E2431–06 (2011)
DESIGN WORKSHEET FOR THERMAL STRESS EVALUATION
PROJECT: NAME: ______________________DATE:__________________
LOCATION: _______________________________________
Glass Type: _______________________
Glass Dimensions: width _________mm length ____________mm thickness____________mm
Perimeter _____________________m
Edge Bite: ______________________________mm
Frame Type: ___________________________
Solar Absorptance (A )__________________
s
Solar Transmittance (T )________________
s
Solar Reflectance of Shade Device (R )__________________
s
Incident solar irradiance (I )___________________W/m
s
Acceptable Probability of Breakage (P ) _____________
b
Compute Solar Load (SL)
SL = I 3 A = _______ W/m
s s
Determine Edge Thermal Stress Factor: Use Figure 1
TSF = ______________kPa/( W/m )
edge
Shadow Thermal Stress Factor (TSF )__________ kPa/(W/m ) (Use Figure 2 and Table 2)
shadow
Determine Total Thermal Stress Factor (TSF )
total
TSF = TSF + TSF , but no greater than 39.4 kPa/(W/m ) for angular shadows or 32.0
total edge shadow
kPa/(W/m ) for all other shadows.
TSF = ________________ kPa/(W/m )
total
Solar Load Adjustment Factor (SLA)_____________(Use Figure 3)
Determine the Calculated thermal stress,s
calculated
s =(TSF 3 SL 3 SLA)/1000 = ______________MPa
calculated total
Determine allowable thermal stress, s , from Figure 4
allowable
s =_______________MPa
allowable
Conclusion:
If s < s OK
calculated allowable
If s < s NG
calculated allowable
FIG. 5 Design Worksheet for Thermal Stress Evaluation
E2431–06 (2011)
APPENDIX
(Nonmandator
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