1、Designation: E 2431 06Standard Practice forDetermining the Resistance of Single Glazed AnnealedArchitectural Flat Glass to Thermal Loadings1This standard is issued under the fixed designation E 2431; the number immediately following the designation indicates the year oforiginal adoption or, in the c
2、ase 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 practice covers a procedure to determine theresistance of annealed architectural fl
3、at glass to thermallyinduced stresses caused by exposure to sun and shadows for aspecified probability of breakage (Pb). Proper use of thisprocedure is intended to reduce the possibility of thermalbreakage of annealed glass in buildings.1.2 This practice applies to vertical or sloped glazing inbuild
4、ings.1.3 This practice applies to monolithic and laminated glassof rectangular shape and assumes that all glass edges aresimply supported.1.4 This practice applies only to annealed flat soda-limesilica glass with clean cut, seamed, flat ground, or ground andpolished edges that are free from damage.
5、The glass may beclear or tinted as well as coated (not including coatings thatreduce emissivity of the glass).1.5 This practice does not apply to any form of wired,patterned, etched, sandblasted, drilled, notched, or groovedglass or glass with surface and edge treatments, other thanthose described i
6、n section 1.4, that alter the glass strength.1.6 This practice does not address uniform loads such aswind and snow loads, safety requirements, fire, or impactresistance.1.7 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly. For c
7、onversion of quantities in various systems ofmeasurements to SI units refer to IEEE/ASTM SI-10.1.8 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health pr
8、actices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Documents:2C 162 Terminology of Glass and Glass ProductsE 631 Terminology of Building ConstructionsIEEE/ASTM SI-10 Use of the International System of Units(SI) (the Modernized Metric Syste
9、m)2.2 Other Documents:32005 ASHRAE Handbook Fundamentals3. Terminology3.1 Definitions:3.1.1 Refer to Terminologies C 162 and E 631 for additionalterms used in this practice3.2 Definitions of Terms Specific to This Standard:3.2.1 edge bite, nthe width of the glass edge (measuredperpendicular to the c
10、ut edge, in the plane of the glass) that isprotected from direct exposure to solar irradiance by thewindow frame edge conditions expressed in mm (in.) SeeTable 1.3.2.2 edge thermal stress factor (TSFedge), nthe ratio ofinduced thermal stress to the solar load, SL, as the result of theedge bite condi
11、tion expressed in MPa/(W/m2).3.2.3 frame type, nthe manner in which the edges of theglass are supported in the window frame See Table 1.3.2.4 glass dimensions, nthe rectangular dimensions ofthe glass (not the daylight opening), with the width being thesmaller dimension and the length being the large
12、r dimensionboth expressed in mm.3.2.5 incident solar irradiance (Insolation), (Is), namountof solar energy per unit time per unit area normal to glass, towhich the glass is exposed expressed in W/m2.1This practice is under the jurisdiction of ASTM Committee E06 on Perfor-mance of Buildings and is th
13、e direct responsibility of Subcommittee E06.51 onPerformance of Windows, Doors, Skylights, and Curtain Walls.Current edition approved Feb. 1, 2006. Published February 2006.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For An
14、nual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc. (ASHRAE), 1791 Tullie Circle, NE, Atlanta, GA30329.1Copyright ASTM International, 100 Barr H
15、arbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.6 probability of breakage (Pb), nthe number of litesper 1000 that would be predicted to break when exposed to thespecified thermal loading conditions.3.2.7 shadow thermal stress factor (TSFshadow), nthe ratioof induced the
16、rmal stress to the solar load, SL, as the result ofshadow condition expressed in MPa/(W/m2) (psi/Btu/hrft2).3.2.8 solar load (SL), nthe total amount of solar irradi-ance absorbed by the glass expressed in W/m2.3.2.9 solar load adjustment factor for interior shadingdevices (SLA), nnondimensional fact
17、or that is used toaccount for the increase in thermal stress caused by thereflection of solar irradiance from an interior shading device.TABLE 1 Frame Types.Frame Type SketchInsulated edge - This condition should only be used in the analysis if it canreasonably be assumed that the heat loss from the
18、 glass to the glazingpocket is negligible.Conventional edge - This condition should be used in the analysis only whenthe glazing pocket is fabricated with thin walled members and the glass iscushioned with gasket materials as shown.High heat mass edge - This condition should be used in the analysis
19、when theglazing is encapsulated in a material with a high heat mass such as concrete,heavy metal, and so forth.E24310623.2.10 solar reflectance of shading device (Rs), ndecimalfraction of incident solar irradiation reflected from the deviceused as an interior shade.3.2.11 solar transmittance (Ts), n
20、the amount of solarirradiance transmitted by the glass expressed as a fraction thatranges between 0.00 and 1.00.3.2.12 thermal stress, nedge tensile stress (MPa) inducedin glass by solar irradiance.3.2.13 total solar absorptance (As), nthe amount of solarirradiance absorbed by the glass expressed as
21、 a fraction thatranges between 0.00 and 1.00.3.2.14 total thermal stress factor (TSFtot), nthe ratio oftotal thermal stress induced in the glass by the combination ofedge conditions and shadow conditions to the solar loadexpressed in MPa/(W/m2).4. Summary of Practice4.1 The specifying authority shal
22、l provide the glass width,length, and nominal thickness; solar absorption of the glassconstruction (can be obtained from manufacturers data);incident solar irradiance (can be determined from 2005ASHRAE Handbook Fundamentals or other documentedsource); the frame type and edge bite; description of ext
23、eriorshading conditions; and interior shading devices.44.2 The procedure described in this practice shall be used todetermine if the glass can resist the calculated thermal stressesfor a specified probability of breakage.5. Significance and Use5.1 Use of this practice assumes:5.1.1 the glass edges s
24、hall be free from damage,5.1.2 the glass shall be properly glazed,5.1.3 the glass shall not have been subjected to abuse, and5.1.4 the glass edge support allows in-plane movement ofthe glass due to thermal expansion and contraction.5.2 This practice does not address all factors that causethermally i
25、nduced stresses in annealed glass. Factors that arenot addressed include: transient thermal stresses, HVAC reg-isters, thermally insulating window coverings, drop ceilingsand other heat traps, increased solar irradiance caused byexterior reflections, variations in heat transfer coefficients othertha
26、n those assumed for the steady state analysis describedherein, and stresses induced by thermal sources other than thesun. Factors other than those listed above may also inducethermal stress.5.3 Many other factors shall be considered in glass selec-tion. These factors include, but are not limited to,
27、 mechanicallyinduced stresses, wind effects, windborne debris impacts,excessive deflections, seismic effects, heat flow, noise abate-ment, potential post-breakage consequences, and so forth. Inaddition, considerations set forth in building codes along withcriteria presented in safety glazing standar
28、ds and site specificconcerns may control the ultimate glass type and thicknessselection.5.4 The proper use of this practice is intended to reduce therisk of thermally induced breakage of annealed window glassin buildings.6. Procedure6.1 Obtain the following information from the data suppliedby the s
29、pecifier:6.1.1 the edge bite condition that most closely represents theproject conditions from Table 1,6.1.2 the total solar transmittance (Ts) of the specified glass,6.1.3 the total solar absorptance (As) of the specified glass.As51.002Ts2 Rs(1)where:Rs= total solar reflectance6.1.4 the solar refle
30、ctance of the shading device (RSD), ifused.6.1.5 the incident solar irradiance (Is) for this analysis.6.1.6 the specified acceptable probability of glass breakage(Pb) for this analysis.6.2 Multiply the incident solar irradiance (Is) by the solarabsorptance (AS) to determine the solar load (SL).6.3 D
31、etermine the edge thermal stress factor (TSFedge) fromFig. 1, given the edge bite and edge bite condition.6.4 Determine the shadow thermal stress factor (TSFshadow)using the common shadow patterns shown in Fig. 2 and thefactors listed in Table 2.6.5 Determine the total thermal stress factor (TSFtota
32、l)bysumming the individual thermal stress factors given in 6.3 and6.4.6.5.1 If the calculated total thermal stress factor exceeds39.4 kPa/(W/m2) when the angular shadow pattern is assumed,that is, Fig. 2 b and d, then 39.4 kPa/(W/m2) shall be used forthe total thermal stress factor.6.5.2 If the calc
33、ulated total thermal stress factor exceeds32.0 kPa/(W/m2) when other shadow patterns, that is, Fig. 2 aand c, are assumed, then 32.0 kPa/(W/m2) shall be used for thetotal thermal stress factor.6.6 To determine the solar load adjustment factor (SLA)using Fig. 3, enter the vertical axis with the solar
34、 reflectance ofthe shading device (RSD) and the horizontal axis with totalsolar transmittance of the glass (TS) to determine the solar loadadjustment factor (SLA) for interior shading devices. If nec-essary use interpolation to estimate the solar load adjustmentfactor (SLA). If no shading device is
35、used, the solar loadadjustment factor (SLA) shall be taken to be 1.0.6.7 Determine the calculated thermal stress, scalculated,bymultiplying the total thermal stress factor (TSFtotal) by the solarload (SL) and by the solar load adjustment factor (SLA).4Beason, W.L., and Lingnell, A.W., “A Thermal Str
36、ess Evaluation Procedurefor Monolithic Annealed Glass,” Use of Glass in Buildings, ASTM STP 1434,V.Block, Ed., American Society for Testing and Materials, West Conshohocken, PA,2003.TABLE 2 Shadow Thermal Stress Factors to be Used with Fig. 2.Shadow Condition Maximum TSFshadowkPa/(W/sq m)Linear shad
37、ow 15.3Angular shadow 31.9L-Shaped shadow 20.8Corner shadow 23.0E24310636.8 Determine the perimeter of the glass lite by adding twicethe width to twice the height.6.9 Determine the allowable thermal stress, sallowable, fromFig. 4 using the glass perimeter and the specified acceptable Pb.6.10 If scal
38、culated sallowable,Pbfor the glass exceeds thespecified probability of breakage for the thermal design con-ditions. If Pbfor the glass exceeds the specified probability ofbreakage, the user shall consider using strengthened glass,modifying the controllable design conditions, or having a morecomprehe
39、nsive thermal stress analysis performed.7. Report7.1 The report shall consist of the design example work-sheet presented in Fig. 5 or, as a minimum, shall include:7.1.1 Project name,7.1.2 Date,7.1.3 Project location,7.1.4 Glass type,7.1.5 Glass dimensions,7.1.6 Edge bite,7.1.7 Frame type,7.1.8 Solar
40、 absorptance (As),7.1.9 Solar transmittance (Ts),7.1.10 Total Solar Reflectance of Shade Device (RSD),7.1.11 Incident solar irradiance (Is),7.1.12 Acceptable probability of breakage (Pb),7.1.13 Allowable thermal stress (sallowable), and7.1.14 Calculated thermal stress (scalculated).7.1.15 Conclusion
41、8. Keywords8.1 annealed glass; thermal stress; thermal breakage; glass;flat glass; soda-lime silica glass; thermal loadFIG. 1 Edge Thermal Stress Factor Chart.E2431064FIG. 2 Shadow Conditions.E2431065FIG. 3 Solar Load Adjustment Factor, SLA.FIG. 4 Probability of Breakage (POB) Chart.E2431066DESIGN W
42、ORKSHEET FOR THERMAL STRESS EVALUATIONPROJECT: NAME: _DATE:_LOCATION: _Glass Type: _Glass Dimensions: width _mm length _mm thickness_mmPerimeter _mEdge Bite: _mmFrame Type: _Solar Absorptance (As)_Solar Transmittance (Ts)_Solar Reflectance of Shade Device (Rs)_Incident solar irradiance (Is)_W/m2Acce
43、ptable Probability of Breakage (Pb) _Compute Solar Load (SL)SL = Is3 As= _ W/m2Determine Edge Thermal Stress Factor: Use Figure 1TSFedge= _kPa/( W/m2)Shadow Thermal Stress Factor (TSFshadow)_ kPa/(W/m2) (Use Figure 2 and Table 2)Determine Total Thermal Stress Factor (TSFtotal)TSFtotal= TSFedge+ TSFs
44、hadow, but no greater than 39.4 kPa/(W/m2) for angular shadows or 32.0kPa/(W/m2) for all other shadows.TSFtotal= _ kPa/(W/m2)Solar Load Adjustment Factor (SLA)_(Use Figure 3)Determine the Calculated thermal stress,scalculatedscalculated=(TSFtotal3 SL 3 SLA)/1000 = _MPaDetermine allowable thermal str
45、ess, sallowable, from Figure 4sallowable=_MPaConclusion:If scalculatedsallowableNGFIG. X1.1 Example 1, Typical Commercial WindowE2431069ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this stan
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48、hich you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.o
