|
oSIST prEN ISO 1288-1:2007
01-november-2007
Steklo v gradbeništvu - Ugotavljanje upogibne trdnosti stekla - 1. del: Osnovno
preskušanje stekla (ISO/DIS 1288-1:2007)
Glazing in building - Determination of the bending strength of glass - Part 1:
Fundamentals of testing glass (ISO/DIS 1288-1:2007)
Glas im Bauwesen - Bestimmung der Biegefestigkeit von Glas - Teil 1: Grundlagen der
Glasprüfungen (ISO/DIS 1288-1:2007)
Verre dans la construction - Détermination de la résistance du verre a la flexion - Partie
1: Principes fondamentaux des essais sur le verre (ISO/DIS 1288-1:2007)
Ta slovenski standard je istoveten z: prEN ISO 1288-1
ICS:
81.040.20 Steklo v gradbeništvu Glass in building
oSIST prEN ISO 1288-1:2007 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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EUROPEAN STANDARD
DRAFT
prEN ISO 1288-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2007
ICS 81.040.20 Will supersede EN 1288-1:2000
English Version
Glazing in building - Determination of the bending strength of
glass - Part 1: Fundamentals of testing glass (ISO/DIS 1288-
1:2007)
Verre dans la construction - Détermination de la résistance
du verre à la flexion - Partie 1: Principes fondamentaux des
essais sur le verre (ISO/DIS 1288-1:2007)
This draft European Standard is submitted to CEN members for parallel enquiry. It has been drawn up by the Technical Committee
CEN/TC 129.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations which
stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other language
made by translation under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the
same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to
provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without notice and
shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2007 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN ISO 1288-1:2007: E
worldwide for CEN national Members.
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prEN ISO 1288-1:2007 (E)
Contents Page
Foreword.3
2
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prEN ISO 1288-1:2007 (E)
Foreword
This document (prEN ISO 1288-1:2007) has been prepared by Technical Committee ISO/TC 160 "Glass in
building" in collaboration with Technical Committee CEN/TC 129 “Glass in building” the secretariat of which is
held by NBN.
This document is currently submitted to the parallel Enquiry.
This document will supersede EN 1288-1:2000.
Endorsement notice
The text of ISO/DIS 1288-1:2007 has been approved by CEN as a prEN ISO 1288-1:2007 without any
modification.
3
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DRAFT INTERNATIONAL STANDARD ISO/DIS 1288-1.2
ISO/TC 160/SC 2 Secretariat: ANSI
Voting begins on Voting terminates on
2007-08-02 2008-01-02
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION • МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ • ORGANISATION INTERNATIONALE DE NORMALISATION
Glazing in building — Determination of the bending strength of
glass —
Part 1:
Fundamentals of testing glass
Verre dans la construction — Détermination de la résistance du verre à la flexion —
Partie 1: Principes fondamentaux des essais sur le verre
ICS 81.040.20
ISO/CEN PARALLEL ENQUIRY
The CEN Secretary-General has advised the ISO Secretary-General that this ISO/DIS covers a
subject of interest to European standardization. In accordance with the ISO-lead mode of
collaboration as defined in the Vienna Agreement, consultation on this ISO/DIS has the same
effect for CEN members as would a CEN enquiry on a draft European Standard. Should this draft
be accepted, a final draft, established on the basis of comments received, will be submitted to a
parallel two-month FDIS vote in ISO and formal vote in CEN.
In accordance with the provisions of Council Resolution 15/1993 this document is circulated
in the English language only.
Conformément aux dispositions de la Résolution du Conseil 15/1993, ce document est
distribué en version anglaise seulement.
To expedite distribution, this document is circulated as received from the committee
secretariat. ISO Central Secretariat work of editing and text composition will be undertaken at
publication stage.
Pour accélérer la distribution, le présent document est distribué tel qu'il est parvenu du
secrétariat du comité. Le travail de rédaction et de composition de texte sera effectué au
Secrétariat central de l'ISO au stade de publication.
THIS DOCUMENT IS A DRAFT CIRCULATED FOR COMMENT AND APPROVAL. IT IS THEREFORE SUBJECT TO CHANGE AND MAY NOT BE REFERRED TO
AS AN INTERNATIONAL STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS BEING ACCEPTABLE FOR INDUSTRIAL, TECHNOLOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL TO BECOME STANDARDS TO WHICH
REFERENCE MAY BE MADE IN NATIONAL REGULATIONS.
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT, WITH THEIR COMMENTS, NOTIFICATION OF ANY RELEVANT PATENT RIGHTS OF WHICH THEY
ARE AWARE AND TO PROVIDE SUPPORTING DOCUMENTATION.
© International Organization for Standardization, 2007
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ISO/DIS 1288-1.2
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Violators may be prosecuted.
ii © ISO 2007 – All rights reserved
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prEN/ISO 1288-1
Contents
Foreword
1 Scope.1
2 Normative references.1
3 Terms and definitions .2
4 Symbols (and abbreviated terms).3
5 Factors to be taken into account when testing glass.4
5.1 Glass as a material .4
5.2 Bending stress and bending strength.6
5.3 Types of glass.6
5.4 Orientation of the specimens .7
5.5 Number of specimens in a sample .7
6 Explanations of the test methods .8
6.1 Coaxial double ring test for large test surface areas.8
6.2 Test with specimen supported at two points (four point bending) .11
6.3 Coaxial double ring test for small test surface areas.13
7 Range of application of the test methods.15
7.1 General limitations .15
7.2 Limitations to EN ISO 1288-2.15
7.3 Limitations to EN ISO 1288-3.15
7.4 Limitations to EN ISO 1288-4.15
7.5 Limitations to EN ISO 1288-5.15
8 Calibration of the testing machines.15
9 Recommendations for safe use of test equipment .16
Bibliography.17
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prEN/ISO 1288-1
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this part of EN ISO 1288 may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard EN ISO 1288-1 was prepared by Technical Committee ISO/TC 160, Glass in building,
Subcommittee SC 2, Use considerations in conjunction with Technical Committee CEN/TC 129, Glass in building.
EN ISO 1288 consists of the following parts, under the general title Glass in building — Determination of the
bending strength of glass:
⎯ Part 1: Fundamentals of testing glass
⎯ Part 2: Coaxial double ring test on flat specimens with large test surface areas
⎯ Part 3: Test with specimen supported at two points (four point bending)
⎯ Part 4: Testing of channel shaped glass
⎯ Part 5: Coaxial double ring test on flat specimens with small test surface areas
This Standard has been based on EN 1288-1 Glass in building - Determination of the bending strength of glass" -
Part 1 : Fundamentals of testing glass prepared by Technical Committee CEN/TC 129 "Glass in building"/WG8
"Mechanical Strength".
According to the CEN/CENELEC Internal Regulations, the national standards organisations of the following
countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland,
France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden,
Switzerland and the United Kingdom.
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prEN/ISO 1288-1
Introduction
A paragraph.
The introduction is an optional preliminary element used, if required, to give specific information or commentary
about the technical content of the standard, and about the reasons prompting its preparation. It shall not contain
requirements.
The introduction shall not be numbered unless there is a need to create numbered subdivisions. In this case, it
shall be numbered 0 with subclauses being numbered 0.1, 0.2, etc. Any numbered figure, table, displayed formula
or footnote shall be numbered normally beginning with 1.
© ISO 1999 – All rights reserved v
DRAFT 2007
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WORKING DRAFT prEN/ISO 1288-1
Glazing in building — Determination of the bending strength of
glass —
Part 1:
Fundamentals of testing glass
1 Scope
This International Standard specifies the determination of the bending strength of monolithic glass for use in
buildings. The testing of insulating units or laminated glass is excluded from this standard.
This standard describes:
- considerations to be taken into account when testing glass,
- explanations of the reasons for designing different test methods,
- limitations of the test methods,
and gives pointers to safety requirements for the personnel operating the test equipment.
EN ISO 1288-2, EN ISO 1288-3, EN ISO 1288-4 and EN ISO 1288-5 specify test methods in detail.
The test methods specified in this standard are intended to provide large numbers of bending strength values that can
be used as the basis for statistical evaluation of glass strength.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this part of EN ISO 1288. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this part of EN ISO 1288 are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
EN ISO 1288-2, Glass in building — Determination of the bending strength of glass — Part 2 : Coaxial double ring
test on flat specimens with large test surface areas
EN ISO 1288-3, Glass in building — Determination of the bending strength of glass — Part 3 : Test with specimen
supported at two points (four point bending)
EN ISO 1288-4, Glass in building — Determination of the bending strength of glass — Part 4 : Testing of channel
shaped glass
EN ISO 1288-5, Glass in building — Determination of the bending strength of glass — Part 5 : Coaxial double ring
test on flat specimens with small test surface areas
EN 572-1, Glass in building — Basic soda lime silicate glass products — Part 1 : Definitions and general physical
and mechanical properties
EN 572-2, Glass in building — Basic soda lime silicate glass products — Part 2 : Float glass
EN 572-3, Glass in building — Basic soda lime silicate glass products — Part 3 : Polished wired glass
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prEN/ISO 1288-1
EN 572-4, Glass in building — Basic soda lime silicate glass products — Part 4 : Drawn sheet glass
EN 572-5, Glass in building — Basic soda lime silicate glass products — Part 5 : Patterned glass
EN 572-6, Glass in building — Basic soda lime silicate glass products — Part 6 : Wired patterned glass
EN 572-7, Glass in building — Basic soda lime silicate glass products — Part 7 : Wired or unwired channel shaped
glass
EN 1748-1, Glass in building — Special basic products — Part 1 : Borosilicate glasses
EN 1748-2, Glass in building — Special basic products — Part 2 : Glass ceramics
EN 1863-1, Glass in building — Heat strengthened soda lime silicate glass — Part 1: Definition and description
EN 12150-1, Glass in building — Thermally toughened soda lime silicate safety glass — Part 1: Definition and
description
EN 12337-1, Glass in building — Chemically strengthened soda lime silicate glass — Part 1: Definition and
description
EN ISO 12543-1, Glass in building — Laminated glass and laminated safety glass — Part 1 : Definitions and
description of component parts
EN 13024-1, Glass in building — Thermally toughened borosilicate safety glass — Part 1: Definition and
description
3 Terms and definitions
For the purposes of this part of EN ISO 1288, the following terms and definitions apply.
3.1
flat glass
any glass product conforming to EN 572-2, EN 572-3, EN 572-4, EN 572-5, EN 572-6, EN 1748-1, EN 1748-2, or
any transformed glass made from these products without deliberately inducing profile or curvature.
3.2
bending stress
the tensile bending stress induced in the surface of a specimen.
NOTE: For testing purposes, the bending stress should be uniform over a specified part of the surface.
3.3
effective bending stress
a weighted average of the tensile bending stresses, calculated by applying a factor to take into account
non-uniformity of the stress field.
3.4
bending strength
the bending stress or effective bending stress which leads to breakage of the specimen.
3.5
equivalent bending strength
the apparent bending strength of patterned glass, for which the irregularities in the thickness do not allow precise
calculation of the bending stress.
3.6
profile bending strength
the quotient of the maximum bending moment and the section modulus of a channel shaped glass. (EN 572-7)
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prEN/ISO 1288-1
3.7
stress intensity factor
a measure of the stress at a crack tip.
3.8
prestressed glass
any glass product conforming to EN 1863, EN 12150, EN 12337, EN 13024.
4 Symbols (and abbreviated terms)
Applied load N
F
h Specimen thickness m
L Length of side of square test sample m
k Constant for calculation of bending stress in EN ISO 1288-3 m
K ,K Constants for calculation of bending stress in EN ISO 1288-5
1 2
M Maximum bending moment Nm
bB
p Gas pressure applied within loading ring in EN ISO 1288-2 Pa
P Profile bending strength (of channel shaped glass) = M /Z Pa
bB bB
r Radius of loading ring m
1
r Radius of supporting ring m
2
r Radius of circular specimen m
3
r Average specimen radius (for evaluation) m
3m
y Central deflection of specimen m
0
3
Z Section modulus ( of channel shaped glass ) m
Poisson number of specimen
µ
NOTE : for soda lime silicate glass (see EN 572-1) a value of 0,23 is used.
Bending stress Pa
σ
b
Effective bending stress Pa
σ
beff
Bending strength Pa
σ
bB
Equivalent bending strength Pa
σ
beqB
Radial stress Pa
σ
rad
Tangential stress Pa
σ
T
Stress in a direction along the length of the specimen Pa
σ
L
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prEN/ISO 1288-1
5 Factors to be taken into account when testing glass
5.1 Glass as a material
5.1.1 General
Glass is a homogeneous isotropic material having almost perfect linear-elastic behaviour over its tensile strength
range.
Glass has a very high compressive strength and theoretically a very high tensile strength, but the surface of the
glass has many irregularities which act as weaknesses when glass is subjected to tensile stress. These
irregularities are caused by attack from moisture and by contact with hard materials (e.g. grit) and are continually
modified by moisture which is always present in the air.
Tensile strengths of around 10 000 MPa can be predicted from the molecular structure, but bulk glass normally fails
at stresses considerably below 100 MPa.
The presence of the irregularities and their modification by moisture contributes to the properties of glass which
need consideration when performing tests of strength.
Because of the very high compressive strength, glass always fails under tensile stress. Since glass in buildings is
very rarely used in direct tension, the most important property for load resistance is the tensile bending strength.
All the tests described in this standard are intended to evaluate the tensile bending strength of glass.
The bending strength is influenced by the following factors:
a) surface condition (see 5.1.2);
b) rate and duration of loading (see 5.1.3);
c) area of surface stressed in tension (see 5.1.4);
d) ambient medium, through stress corrosion cracking as well as healing of surface damage in the glass (see
5.1.5 and [1] in Bibliography));
e) age, i.e. time elapsing since the last mechanical surface treatment or modification to simulate damage (see
5.1.6);
f) temperature (see 5.1.7).
The influence exerted by factors b) to f) on bending strength has been taken into account in this standard.
5.1.2 Effect of surface condition
For the purpose of bending strength tests according to this standard, glass behaves as an almost ideally linear-
elastic material that fails in a brittle manner. This brittleness means that contact with any hard object can lead to
surface damage in the form of ultra-fine, partly submicroscopic cracks and chips. Surface damage of this kind,
which is practically unavoidable during normal handling of glass, exerts a notch action which is a major factor in
reducing mechanical strength, whereas the chemical composition of the glass has only a minor and in some cases
entirely negligible, significance.
Hence it follows that the bending strength determined by the methods referred to in this standard is related largely
to the surface condition of the specimen to be tested.
This surface condition is characterized by the following main features.
a) The surface condition imparted by a particular method of treatment, which produces a specific damage
spectrum and thus results in a strength which is specific to the finished surface condition;
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prEN/ISO 1288-1
b) Residual stress, e.g. in the form of thermal or chemical prestress intentionally imparted, as well as unintended
residual stresses.
5.1.3 Effect of rate of loading
For the interpretation of the bending strength values determined as described in this standard, the rate of loading is
of special importance.
Cracks propagate in glass over a wide range of values of tensile stress (see [2] in Bibliography)). There is a lower
limit to the stress intensity factor below which cracks do not propagate ( see [1] in Bibliography)). There is then
some subcritical crack propagation at higher levels of stress intensity factor, which is influenced by humidity,
temperature and chemical agents. Above a critical stress intensity factor crack propagation is very rapid and leads
to (almost) instantaneous failure. The consequence of the subcritical crack propagation is, for example, that the
rate of load increase and/or the duration of static loading influences the bending strength.
For prestressed glass, this time dependence does not manifest itself until the tensile stress induced in the surface
exceeds the compressive stress permanently present there (see [3] in Bibliography)).
5.1.4 Effect of test surface area
The decrease in bending strength of glass with increasing size of the test area exposed to high stress is also of
importance (see [4] in Bibliography)). This area effect is accounted for by the statistical distribution of surface
defects varying in effectiveness; the larger the test area, the greater is the probability of its containing a large
surface defect. Consequently, the influence of the area effect increases with decreasing incidence of defects in the
surface, so that this influence is more pronounced in the case of undamaged, e.g. fire-finished glass surfaces (see
[5] in Bibliography).
Differences are likely between the mean values of the bending strength as measured in accordance with EN ISO
2
1288-2 (maximally stressed area: 240 000 mm ), or by using devices R105, R60, R45 and R30 in accordance with
2 2 2 2
EN ISO 1288-5 (maximally stressed areas: 3850 mm , 1260 mm , 254 mm and 113 mm ), due to the size of the
stressed area. Depending on surface damage, the results obtained from testing smaller surface areas may be
significantly higher than those obtained from testing larger surface areas, as shown in table 1.
Table 1 — Approximate effects of test surface area on the mean measured bending strength
Test Method Device Relative bending strength
EN ISO 1288-2 -- 100 %
EN ISO 1288-5 R105 120 % to 180 %
EN ISO 1288-5 R65 125 % to 210 %
EN ISO 1288-5 R45 140 % to 270 %
EN ISO 1288-5 R30 145 % to 300 %
Since glass for use in buildings is often in large sizes, the test methods specified in EN ISO 1288-2 and EN ISO
1288-3 give values which are more appropriate as the basis for designing flat glass for use in buildings. The test
method specified in EN ISO 1288-5 can be useful as a method of evaluating the comparative bending strength of
flat glass.
5.1.5 Effect of ambient medium
The surrounding medium in which the glass is tested has an influence on the strength of the glass, particularly if
the moisture level is very low. When glass is used in buildings, the relative humidity typically ranges from 30 % to
100 %. Within this range, the effect on the bending strength, as tested according to this standard, is not great.
However, tests on glass for use in buildings shall be undertaken in test conditions with relative humidity levels in
the range of 40 % to 70 %, in order to eliminate this effect when comparing bending strength results.
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prEN/ISO 1288-1
5.1.6 Effect of aging
If the glass surface is modified (by abrasion, etching, edge working etc.) before the testing, it is necessary to allow
the fresh damage to heal before the test is undertaken. The continual surface modification by moisture affects the
damage in a way that can reduce any weakening effect (see [1] of Bibliography). In practice, glass is highly
unlikely to be stressed directly after it has been treated, so it shall be conditioned for at least 24 h before testing.
5.1.7 Effect of temperature
The bending strength of glass is affected by changes in temperature. Within the normal range of temperatures
experienced by glass in buildings, this effect is not very significant, but, to avoid possible complications in the
comparison of bending strength values, testing shall be undertaken in a restricted range of temperatures.
5.2 Bending stress and bending strength
5.2.1 General
The test methods described in EN ISO 1288-2, EN ISO 1288-3, EN ISO 1288-4 and EN ISO 1288-5 are designed
to induce a uniform bending stress over an area (the test area) of the specimen. However, the tests are statically
indeterminate, that is, the stresses induced by the applied loads depend on the nature of the material tested as well
as the load distribution.
5.2.2 Effective stress
Where the stress varie
...