oSIST ISO/DIS 28841:2010
Guidelines for simplified seismic assessment and rehabilitation of concrete buildings
Guidelines for simplified seismic assessment and rehabilitation of concrete buildings
The purpose of ISO 28841:2013 is to provide sufficient information to perform the seismic assessment and rehabilitation of the structural concrete building that complies with the limitations established in ISO 28841:2013, for both undamaged structures that are deemed not to comply with the required characteristics for an adequate response at a specified performance level, and for structures that have undergone damage under seismic loadings. The rules of design as set forth in ISO 28841:2013 are simplifications of more elaborate requirements.
ISO 28841:2013 can be used as an alternative to the development of a building code, or equivalent document in countries where no national design codes are available by themselves, or as an alternative to the building code in countries where specifically considered and accepted by the national standards body or other appropriate regulatory organization, and applies to the assessment of earthquake resistance capability and to the seismic rehabilitation design and construction for existing structural concrete buildings.
Norme pour l'évaluation sismique simplifiée et la réhabilitation des structures en béton
Smernice za poenostavljene ocene potresne varnosti in sanacijo betonskih zgradb
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INTERNATIONAL ISO
STANDARD 28841
First edition
2013-06-01
Guidelines for simplified seismic
assessment and rehabilitation of
concrete buildings
Lignes directrices pour l'évaluation sismique simplifiée et la
réhabilitation des structures en béton
Reference number
ISO 28841:2013(E)
©
ISO 2013
---------------------- Page: 1 ----------------------
ISO 28841:2013(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2013
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ii © ISO 2013 – All rights reserved
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ISO 28841:2013(E)
Contents Page
Foreword . v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols and abbreviated terms . 13
5 Limitations . 17
5.1 Occupancy . 17
5.2 Maximum number of stories . 18
5.3 Maximum aspect ratios . 18
5.4 Maximum story height . 18
5.5 Maximum difference in story height . 18
5.6 Maximum difference in floor area . 18
5.7 Maximum difference in story mass . 18
5.8 Maximum column offset . 18
5.9 Maximum span length . 18
5.10 Maximum difference in span length . 18
5.11 Maximum cantilever span . 18
5.12 Maximum slope for slabs, girders, beams and joists . 19
5.13 Maximum slope of the terrain . 19
5.14 Distance between center of mass and center of rigidity . 19
6 Assessment and rehabilitation procedure. 19
6.1 Procedure outline . 19
6.2 Data collection . 20
6.3 Lateral load resisting system classification . 21
6.4 Material assessment . 21
6.5 Condition assessment . 21
6.6 Structural assessment . 21
6.7 Rehabilitation design . 21
6.8 Rehabilitation construction . 21
6.9 Design documentation . 21
7 General Guides . 23
7.1 Limit states . 23
7.2 Ultimate limit state design format . 23
7.3 Serviceability limit state design format . 24
8 Classification of the structure system of the building . 24
8.1 Concrete frame systems . 24
8.2 Concrete wall systems . 24
8.3 Concrete dual systems . 25
9 Condition assessment of structures damaged by a seismic event . 25
9.1 Material assessment . 25
9.2 Condition Assessment . 28
9.3 Structural assessment . 41
9.4 Final assessment . 41
10 Condition assessment of existing structures . 41
10.1 Vulnerability level . 41
10.2 Actual condition of the structure . 42
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ISO 28841:2013(E)
10.3 Seismic hazard . 43
10.4 Architectural layout . 45
10.5 Foundation . 50
10.6 Soil type . 50
10.7 Quality aspects . 50
10.8 Structural assessment . 51
10.9 Final assessment . 52
11 Rehabilitation analysis and design . 54
11.1 Concrete Frame Systems . 54
11.2 Concrete wall systems . 54
11.3 Concrete frames with concrete infills . 55
11.4 Foundation rehabilitation . 55
11.5 Rehabilitation Measures for the structural system . 55
12 Rehabilitation construction . 57
12.1 Demolitions and debris retrieval . 57
12.2 Cover retrieval . 57
12.3 Surface preparations . 57
12.4 Adherence concerns . 58
12.5 Durability concerns . 58
Annex A (normative) Structural Assessment . 59
A.1 Resistance . 59
A.2 Story drift . 63
A.3 Energy dissipation level . 65
A.4 Equivalent equations for material factors . 69
A.5 Equivalent equations for material factors . 73
Bibliography . 76
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ISO 28841:2013(E)
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.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of
ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2. www.iso.org/directives
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent
rights identified during the development of the document will be in the Introduction and/or on the ISO list of
patent declarations received. www.iso.org/patents
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
The committee responsible for this document is ISO/TC 71, Concrete, reinforced concrete and pre-stressed
concrete, Subcommittee SC 5, Simplified design standard for concrete structures.
© ISO 2013 – All rights reserved v
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ISO 28841:2013(E)
Introduction
The aim of this International Standard is to provide rules for the earthquake resistant assessment and
rehabilitation design and execution for existing structural concrete buildings for which simplified procedures
may be applied instead of more sophisticated and thorough analyses, in light of the simplicity, symmetry, and
other characteristics of the structure under study. This International Standard is developed for countries that
do not have existing national standards on this subject and to offer, to local regulatory authorities anywhere,
an alternative for the study of relatively small and simple buildings that abound in both rural and urban
environments. The analysis and design rules are based in simplified worldwide-accepted strength models.
This International Standard is self-contained; therefore actions (loads), simplified analysis procedures and
design specifications are included, as well as minimum acceptable construction practice guidelines.
The minimum dimensional guidelines contained in this International Standard are intended to account for
undesirable side effects that will otherwise require more sophisticated analysis and design procedures.
Material and construction guidelines are aimed at site-mixed concrete as well as ready-mixed concrete, and
steel of the minimum available strength grades.
The earthquake resistance guidelines are included for rehabilitation of concrete buildings in the numerous
regions of the world which lie in earthquake prone areas. The earthquake resistance of rehabilitated buildings
is based upon the employment of structural concrete walls (shear walls) that limit the lateral deformations of
the structure and provide for its lateral strength.
This International Standard contains guidelines that can be modified by the national standards body due to
local design and construction requirements and practices. These guidelines that can be modified are included
using ["boxed values"]. The authorities in each member country are expected to review the "boxed values"
and may substitute alternative definitive values for these elements for use in the national application of this
International Standard. Changes to boxed values shall not be made without thorough analyses and sound
supporting studies.
A great effort was made to include self-explanatory tables, graphics, and design aids to simplify the use of this
International Standard and provide foolproof procedures. Notwithstanding, the economic implications of the
conservatism inherent in approximate procedures as a substitute for sound and experienced engineering
should be a matter of concern to the designer that employs the document, and to the owner that hires him.
vi © ISO 2013 – All rights reserved
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INTERNATIONAL STANDARD ISO 28841:2013(E)
Guidelines for simplified seismic assessment and rehabilitation
of concrete buildings
1 Scope
This International Standard can be used as an alternative to the development of a building code, or equivalent
document in countries where no national design codes are available by themselves, or as an alternative to the
building code in countries where specifically considered and accepted by the national standards body or other
appropriate regulatory organization, and applies to the assessment of earthquake resistance capability and to
the seismic rehabilitation design and construction for existing structural concrete buildings.
The purpose of these guidelines is to provide sufficient information to perform the seismic assessment and
rehabilitation of the structural concrete building that complies with the limitations established in Clause 5, for
both undamaged structures that are deemed not to comply with the required characteristics for an adequate
response at a specified performance level, and for structures that have undergone damage under seismic
loadings. The rules of design as set forth in this International Standard are simplifications of more elaborate
requirements.
Although the guidelines contained in this International Standard were drawn to produce, when properly
employed, a reasonable assessment of the seismic vulnerability of an undamaged structure, a reasonable
assessment of a structure damaged by a seismic event and a structural rehabilitation of the assessed
concrete structure with an appropriate margin of safety, these guidelines are not a replacement for sound and
experienced engineering. In order to attain the intended results on assessment and rehabilitation design, this
International Standard must be used as a whole, and alternative procedures should be employed only when
explicitly permitted by the guidelines. The minimum dimensioning guides as prescribed in this International
Standard replace, in most cases, more elaborate procedures such as those prescribed in the national code or,
if no national code exists, in internationally recognized full fledged codes, and the possible economic impact is
compensated for by the simplicity of the procedures prescribed here.
The professional applying the procedures set forth by these guidelines should meet the legal requirements for
structural designers in the country of adoption and have training and a minimum appropriate knowledge of
structural mechanics, statics, strength of materials, structural analysis, and reinforced concrete design and
construction.
While buildings rehabilitated in accordance with these guidelines are expected to perform within the selected
performance levels for the applicable design earthquakes, compliance with these guidelines is necessary but
may not guarantee the sought for performance, as current knowledge of structural behavior under seismic
loads, and of the loads themselves, is still incomplete.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 15673:2005, Guidelines for the simplified design of structural reinforced concrete for buildings
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ISO 28841:2013(E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
acceleration of gravity, g
acceleration produced by gravity at the surface of the earth
2
NOTE For the application of these guidelines its value can be approximated to 10 m/s .
3.2
adherence
force acting on the interface of two solid materials
3.3
admixture
material other than water, aggregate, or hydraulic cement, added to concrete before or during its mixing to
modify its properties
3.4
aggregate
granular material, such as sand, gravel, crushed stone, and iron blast-furnace slag, used in conjunction with
cementitious materials to form a hydraulic cement concrete or mortar
3.5
anchorage
devices used to anchor a non-structural element to the structural framing
3.6
bar diameter, nominal
approximate diameter of a steel reinforcing bar, often used as a class designation
NOTE For deformed bars, it is common practice to use the diameter of a plain bar having the same area.
3.7
beam
structural member for which ratio of axial load to axial gross capacity is equal to or less than 0,1.
3.8
bearing capacity of the soil
maximum permissible stress on the foundation soil that provides adequate safety against bearing failure of the
soil
NOTE Its value is defined at the working stress level.
3.9
bending moment
product of a force and the distance to a particular axis, producing bending effects in a structural element
3.10
boundary elements
structural elements embedded at the ends of structural walls strengthened by transverse reinforcement to
confine the longitudinal reinforcement
NOTE Boundary elements may require an increase in thickness of the wall.
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ISO 28841:2013(E)
3.11
caisson
foundation pile of large diameter, built partly or totally above ground and sunk below ground usually by digging
out the soil inside
3.12
carbonation
process of conversion of calcium hydroxide in hardened cementitious material into calcium carbonate due to
reaction with carbon dioxide diffused into the cement paste from the atmosphere
3.13
cement
material as specified in the corresponding referenced ISO standards, which, when mixed with water, has
hardening properties
3.14
center of mass
geometric plan location of the resultant force due to the action of gravity on the mass of the floor is located,
supposing the floor diaphragm as an infinite rigid body in its own plane
3.15
center of rigidity
geometric plan location of the resultant of the resistance forces due to structural vertical elements stiffness,
calculated, supposing that the floor diaphragm is an infinite rigid body in its own plane in such a way that when
applying a horizontal force in any direction, rotation of the diaphragm takes place with no distortion of the
original shape of the floor
3.16
corrosion
process of disintegration of the reinforcing steel bars due to chemical or electromechanical change caused in
presence of moisture
3.17
column
structural member in which the ratio of axial compressive loads to axial gross capacity is more than 0,1
3.18
collector elements
structural elements that carry the forces within a horizontal diaphragm to the lateral-force resisting system
3.19
combined footing
footing that transmits to the supporting soil the load carried by several columns or structural concrete walls
3.20
compression reinforcement
reinforcement provided to resist compression stresses in the member section
3.21
concrete
mixture of cementitious materials with fine aggregate, coarse aggregate, and water, with or without admixtures,
to form a hardened material with specific strength properties
3.22
concrete mix design
choice and proportioning of the ingredients of concrete
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ISO 28841:2013(E)
3.23
concrete specified compressive strength, f
c
compressive strength of cylindrical concrete specimens used in design and evaluated in accordance with the
appropriate ISO standard, expressed in megapascals (MPa)
' '
NOTE Whenever the quantity f is under a radical sign ( f ), the positive square root of numerical value only is
c c
intended, and the corresponding result has units of megapascals (MPa).
3.24
confinement hook
hook at the ends of a stirrup, hoop, or crosstie having a bend of not less than 135° with a six-diameter (but not
less than 75 mm) extension that engages the longitudinal reinforcement and projects into the interior of the
stirrup, hoop or crosstie
3.25
confinement stirrup or tie
closed stirrup, tie or continuously wound spiral
NOTE A closed stirrup or tie can be made up of several reinforcement elements each having confinement hooks at
both ends. A continuously wound spiral should have a confinement hook at both ends.
3.26
cover, concrete
thickness of concrete between the surface of any reinforcing bar and the nearest face of the concrete member
3.27
crack
break, with or without quite separating in two parts, of concrete, usually near or at the surface
3.28
creep
unrecoverable strain caused to a material subjected to constant stress for a long duration
3.29
crosstie
continuous reinforcing bar having a 135° hook at one end and a hook not less than 90° at least a six-diameter
extension at the other end
NOTE The hooks should engage peripheral longitudinal bars. The 90° hooks of two successive crossties engaging
the same longitudinal bars should be alternated end for end.
3.30
curing
process in which concrete is kept damp for a period of several days, starting from the moment it is cast, in
order to prevent evaporation of water within the cementitious paste to ensure that the hardening process
attains the intended strength
NOTE Appropriate curing will greatly reduce shrinkage, increase strength of concrete, and should reduce surface
cracking. Curing time will depend on temperature and relative humidity of surrounding air, the amount of wind, the direct
sunlight exposure, the type of concrete mix employed, and other factors.
3.31
dead load
permanent load
load in which variations over time are rare or of small magnitude
NOTE All other loads are variable loads (see also nominal loads).
4 © ISO 2013 – All rights reserved
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ISO 28841:2013(E)
3.32
deformed reinforcement
steel reinforcement that has deformations in its surface to increase its bond to the concrete
NOTE The following steel reinforcement should be considered deformed reinforcement under these guidelines:
deformed reinforcing bars, deformed wire, welded plain wire fabric, and welded deformed wire fabric conforming to the
appropriate ISO standards.
3.33
depth of member, h
vertical dimension of a cross section of a horizontal structural element or cross section dimension parallel to
the direction of transversally applied loads to vertical structural elements
3.34
design load combinations
combinations of factored loads and forces as specified in these guidelines
3.35
design strength
product of the nominal strength and a strength reduction factor
3.36
development length
length of embedded reinforcement required to develop the design strength of reinforcement at a critical
section
3.37
development length for a bar with a standard hook
minimum length to be provided between the critical section (where the strength of the bar is to be developed)
and a tangent to the outer edge of the 90° or 180° hook
3.38
differential settlement
non-uniform vertical displacement of the foundation
3.39
drift
difference between the horizontal displacements of two floor levels
3.40
durability
characteristics of a structure to resist gradual degradation of its serviceability in a given environment for the
design service life
3.41
effective depth of section, d
distance measured from extreme compression fiber to centroid of tension reinforcement
3.42
embedment length
length of embedded reinforcement provided beyond a critical section
3.43
fatigue
weakening of a material by load cycles, with or without load reversals
3.44
factored loads and forces
specified nominal loads and forces multiplied by the load factors prescribed in these guidelines
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ISO 28841:2013(E)
3.45
fire protection of reinforcement
amount of concrete cover necessary for protection of the reinforcement against the effects of the high
temperatures produced by fire
NOTE The concrete cover is a function of specified fire resistance, measured in hours.
3.46
flange
top or bottom part of an “I” or “T” shaped section
3.47
flexural
pertaining to the effect of flexure
3.48
flexural reinforcement
reinforcement provided to resist the tensile stresses induced by flexural moments acting on the member
section
3.49
footing
that portion of the foundation which transmits loads directly to the soil
NOTE May be the widening part of a column, a structural concrete wall or several columns, in a combined footing.
3.50
formwork
temporary construction to contain concrete in a plastic state while it is cast and setting, and which provides the
final shape of the element as the concrete hardens
3.51
foundation
part of the structure that transmits loads to the underlying
...
SLOVENSKI STANDARD
oSIST ISO/DIS 28841:2010
01-november-2010
Smernice za poenostavljene ocene potresne varnosti in sanacijo betonskih
zgradb
Guidelines for simplified seismic assessment and rehabilitation of concrete buildings
Norme pour l'évaluation sismique simplifiée et la réhabilitation des structures en béton
Ta slovenski standard je istoveten z: ISO/DIS 28841
ICS:
91.080.40 Betonske konstrukcije Concrete structures
91.120.25 =DãþLWDSUHGSRWUHVLLQ Seismic and vibration
YLEUDFLMDPL protection
oSIST ISO/DIS 28841:2010 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST ISO/DIS 28841:2010
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oSIST ISO/DIS 28841:2010
DRAFT INTERNATIONAL STANDARD ISO/DIS 28841
ISO/TC 71/SC 5 Secretariat: ICONTEC
Voting begins on: Voting terminates on:
2010-06-15 2010-11-15
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION • МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ • ORGANISATION INTERNATIONALE DE NORMALISATION
Guidelines for simplified seismic assessment and rehabilitation
of concrete buildings
Norme pour l'évaluation sismique simplifiée et la réhabilitation des structures en béton
ICS 91.080.40
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, 2010
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oSIST ISO/DIS 28841:2010
ISO/DIS 28841
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©
ii ISO 2010 – All rights reserved
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oSIST ISO/DIS 28841:2010
ISO/DIS 28841
Contents Page
Foreword .v
Introduction.vi
1 Scope.1
2 Normative references.1
3 Terms and definitions .2
4 Symbols (and abbreviated terms).13
5 Limitations .23
5.1 Occupancy .23
5.1.1 Permitted occupancy .23
5.1.2 Mixed occupancy.24
5.2 Maximum number of stories .24
5.3 Maximum aspect ratios.24
5.4 Maximum story height .24
5.5 Maximum span length.25
5.6 Maximum difference in span length .25
5.7 Maximum cantilever span.25
5.8 Maximum slope for slabs, girders, beams and joists.25
5.9 Maximum slope of the terrain .25
5.10 Distance between center of mass and center of rigidity.25
6 Assessment and rehabilitation procedure.26
6.1 Procedure outline.26
6.2 Data collection.27
6.3 Lateral load resisting system classification.27
6.4 Material assessment .27
6.5 Condition assessment .27
6.6 Structural assessment.27
6.7 Rehabilitation design .27
6.8 Rehabilitation construction.27
6.9 Design documentation.28
6.9.1 Assessment record .28
6.9.2 Rehabilitation calculation memoir.28
6.9.3 Geotechnical report.28
6.9.4 Structural drawings.28
6.9.5 Specifications .29
7 General Guides.29
7.1 Limit states.29
7.2 Ultimate limit state design format.29
7.2.1 General .29
7.2.2 Required factored strength .30
7.3 Serviceability limit state design format.30
8 Classification of the structure system of the building .31
8.1 Concrete frame systems.31
8.2 Concrete wall systems.31
8.3 Concrete dual systems .31
9 Condition assessment of structures damaged by a seismic event .32
9.1 Material assessment .32
9.1.1 Material properties .33
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oSIST ISO/DIS 28841:2010
ISO/DIS 28841
9.1.2 Component properties . 33
9.1.3 Test methods. 34
9.1.4 Minimum number of tests . 34
9.1.5 Soundness. 35
9.2 Condition Assessment. 35
9.2.1 Layout of structural damages . 35
9.2.2 Damage levels. 37
9.2.3 Layout of non structural damages. 50
9.3 Structural assessment . 51
9.4 Final assessment. 51
10 Condition assessment of existing structures.51
10.1 Vulnerability level . 52
10.2 Actual condition of the structure . 52
10.3 Seismic hazard. 53
10.3.1 No seismic hazard zones . 56
10.3.2 Low seismic hazard zones. 56
10.3.3 Intermediate seismic hazard zones . 56
10.3.4 High seismic hazard zones. 56
10.4 Architectural layout . 56
10.4.1 Plan irregularity. 56
10.4.2 Elevation irregularity . 58
10.5 Foundation . 61
10.6 Soil type . 61
10.7 Quality aspects . 61
10.7.1 Quality of design. 61
10.7.2 Quality of materials . 62
10.7.3 Quality of construction . 62
10.7.4 Non structural elements. 62
10.8 Structural assessment . 62
10.9 Final assessment. 63
11 Rehabilitation analysis and design. 65
11.1 Concrete Frame Systems. 65
11.2 Concrete wall systems . 65
11.3 Concrete frames with concrete infills. 65
11.4 Foundation rehabilitation. 65
11.5 Rehabilitation Measures for the structural system. 66
11.5.1 Reinforced concrete jacketing . 66
11.5.2 Shotcreting. 66
11.5.3 FRP reinforcements. 67
12 Rehabilitation construction . 68
12.1 Demolitions and debris retrieval. 68
12.2 Cover retrieval. 68
12.3 Surface preparations. 68
12.4 Adherence concerns . 68
12.5 Durability concerns . 69
Bibliography. 70
Annex A (Normative) Structural Assessment. 71
A.1 Resistance. 71
A.1.1 Design strength for flexure only . 71
A.1.2 Design strength for axial compression . 72
A.1.3 Balanced strength for axial compression with flexure. 72
A.1.4 Design strength for axial tension without flexure. 73
A.1.5 Minimum design combined axial load and moment strength. 73
A.2 Flexibility . 75
A.3 Energy dissipation level. 76
A.3.1 Required energy dissipation level . 76
iv
© ISO 2009 – All rights reserved
DRAFT 2010
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oSIST ISO/DIS 28841:2010
ISO/DIS 28841
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 2.
The main task of technical committees is to prepare International Standards. 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 document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 28841 was prepared by Technical Committee ISO/TC 71, Concrete, reinforced concrete and pre-stressed
concrete, Subcommittee SC 05, Simplified design standard for concrete structures.
© ISO 2009 – All rights reserved v
DRAFT 2010
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oSIST ISO/DIS 28841:2010
ISO/DIS 28841
Introduction
The aim of these International Guidelines is to provide rules for the earthquake resistant assessment and
rehabilitation design and execution for existing structural concrete buildings for which simplified procedures
may be applied instead of more sophisticated and thorough analyses, in light of the simplicity, symmetry, and
other characteristics of the structure under study. This document is developed for countries that do not have
existing national standards on this subject and to offer, to local regulatory authorities anywhere, an alternative
for the study of relatively small and simple buildings that abound in both rural and urban environments. The
analysis and design rules are based in simplified worldwide-accepted strength models. The document is self-
contained; therefore actions (loads), simplified analysis procedures and design specifications are included, as
well as minimum acceptable construction practice guidelines.
The minimum dimensional guidelines contained in this document are intended to account for undesirable side
effects that will otherwise require more sophisticated analysis and design procedures. Material and
construction guidelines are aimed at site mixed concrete as well as ready-mixed concrete, and steel of the
minimum available strength grades.
The earthquake resistance guidelines are included for rehabilitation of concrete buildings in the numerous
regions of the world which lay in earthquake prone areas. The earthquake resistance of rehabilitated buildings
is based upon the employment of structural concrete walls (shear walls) that limit the lateral deformations of
the structure and provide for its lateral strength.
The document contains guidelines that can be modified by the national standards body due to local design
and construction requirements and practices. These guidelines that can be modified are included using
["boxed values"]. The authorities in each member country are expected to review the "boxed values" and may
substitute alternative definitive values for these elements for use in the national application of the document.
A great effort was made to include self-explanatory tables, graphics, and design aids to simplify the use of the
document and provide foolproof procedures. Notwithstanding, the economic implications of the conservatism
inherent in approximate procedures as a substitution to sound and experienced engineering should be a
matter of concern to the designer that employs the document, and to the owner that hires him.
vi
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oSIST ISO/DIS 28841:2010
ISO/DIS 28841
Guidelines for simplified seismic assessment and rehabilitation
of concrete buildings
1 Scope
This document can be permitted to be used as an alternative to the development of a building code, or
equivalent document in countries where no national design codes are available by themselves, or as
an alternative to the building code in countries where specifically considered and accepted by the
national standards body or other appropriate regulatory organization, and applies to the assessment of
earthquake resistance capability and to the seismic rehabilitation design and construction for existing
structural concrete buildings.
The purpose of these guidelines is to provide a registered civil engineer with sufficient information to
perform the seismic assessment and rehabilitation of the structural concrete building that complies with
the limitations established in 5., for both undamaged structures that are deemed not to comply with the
required characteristics for an adequate response at a specified performance level, and for structures
that have undergone damages under seismic loadings. The rules of design as set forth in the present
document are simplifications of more elaborate requirements.
Although the guidelines contained in this document were drawn to produce, when properly employed,
a reasonable assessment of the seismic vulnerability of an undamaged structure, a reasonable
assessment of a structure damaged by a seismic event and a structural rehabilitation of the assessed
concrete structure with an appropriate margin of safety, these guidelines are not a replacement of
sound and experienced engineering. In order to attain the intended results on assessment and
rehabilitation design, the document must be used as a whole, and alternative procedures should be
employed only when explicitly permitted by the guidelines. The minimum dimensioning guides as
prescribed in the document replace, in most cases, more elaborate procedures as those prescribed in
the national code or, if no national code exists, in internationally recognized full fledged codes, and the
eventual economic impact is compensated by the simplicity of the procedures prescribed here.
The professional applying the procedures set forth by these guidelines should meet the legal
requirements for structural designers in the country of adoption and have training and a minimum
appropriate knowledge of structural mechanics, statics, strength of materials, structural analysis, and
reinforced concrete design and construction.
While buildings rehabilitated in accordance with these guidelines are expected to perform within the
selected performance levels for the applicable design earthquakes, compliance with this guidelines are
necessary but may not guarantee the sought for performance, as current knowledge of structural
behavior under seismic loads, and of the loads themselves, is yet incomplete.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 679, Methods of testing cements - Determination of strength
ISO 680, Cement - Test methods - Chemical analysis
ISO 863, Cement - Test methods - Pozzolanicity test for pozzolanic cements
© ISO 2009 – All rights reserved 1
DRAFT 2010
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oSIST ISO/DIS 28841:2010
ISO/DIS 28841
ISO 3010, Bases for design of structures - Seismic actions on structures
ISO 4354, Wind actions on structures
ISO 6274, Concrete - Sieve analysis of aggregates
ISO 6782, Aggregates for concrete - Determination of bulk density
ISO 6783, Coarse aggregates for concrete - Determination of particle density and water absorption -
Hydrostatic balance method
ISO 6934-1, Steel for the prestressing of concrete Part 1: General requirements
ISO 6934-3, Steel for the prestressing of concrete -- Part 3: Quenched and tempered wire
ISO 6934-4, Steel for the prestressing of concrete -- Part 4: Strand
ISO 6934-5, Steel for the prestressing of concrete -- Part 5: Hot-rolled steel bars with or without
subsequent processing
ISO 6935-1, Steel for the reinforcement of concrete - Part 1: Plain bars
ISO 6935-2, Steel for the reinforcement of concrete - Part 2: Ribbed bars
ISO 6935-3, Cor: 2000 Steel for the reinforcement of concrete - Part 3: Welded fabric
ISO 7033, Fine and coarse aggregates for concrete - Determination of the particle mass-per-volume
and water absorption - Pycnometer method
ISO 9194, Bases for design of structures - Actions due to the self-weight of structures, non-structural
elements and stored materials – Density
ISO 9597, Cements - Test methods - Determination of setting time and soundness
ISO 10144, Certification scheme for steel bars and wires for the reinforcement of concrete. Welded-
wire fabric
ISO 3766,2003 Construction drawings -- Simplified representation of concrete reinforcement.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
acceleration of gravity
g
the acceleration produced by gravity at the surface of earth
2
NOTE For the application of this guidelines its value can be app
...
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