SIST EN 13001-1:2005+A1:2009
(Main)Cranes - General design - Part 1: General principles and requirements
Cranes - General design - Part 1: General principles and requirements
This European Standard is to be used together with Part 2 and Part 3, and as such, they specify general conditions, requirements and methods to prevent mechanical hazards of cranes by design and theoretical verification. Part 3 is only at pre-drafting stage; the use of Parts 1 and 2 is not conditional to the publication of Part 3.
NOTE Specific requirements for particular types of crane are given in the appropriate European Standard for the particular crane type.
The following is a list of significant hazardous situations and hazardous events that could result in risks to persons during normal use and foreseeable misuse. Clause 4 of this standard is necessary to reduce or eliminate the risks associated with the following hazards:
a) rigid body instability of the crane or its parts (tilting, shifting);
b) exceeding the limits of strength (yield, ultimate, fatigue);
c) elastic instability of the crane or its parts (buckling, bulging);
d) exceeding temperature limits of material or components;
e) exceeding the deformation limits.
This European Standard is applicable to cranes which are manufactured after the date of approval by CEN of this standard and serves as reference base for the European Standards for particular crane types.
Krane - Konstruktion allgemein - Teil 1: Allgemeine Prinzipien und Anforderungen
Appareils de levage à charge suspendue - Conception générale - Partie 1: Principes généraux et prescriptions
La présente Norme européenne doit être utilisée avec les parties 2 et 3 qui spécifient les conditions, prescriptions et
méthodes générales afin d'éviter les risques mécaniques liés aux appareils de levage à charge suspendue, en
utilisant la conception et la vérification théorique. La partie 3 est à l’étape d’avant-projet ; l’utilisation des parties 1 et 2
n’est pas conditionnée par la publication de la partie 3.
NOTE Les prescriptions spécifiques relatives aux types particuliers d’appareil de levage à charge suspendue sont données
dans la norme européenne appropriée au type particulier de grue.
La liste suivante spécifie les situations et les événements dangereux significatifs, susceptibles d'entraîner des risques
pour les personnes lors d'une utilisation normale et d'une mauvaise utilisation prévisible. L'Article 4 de la présente
norme est nécessaire pour réduire ou éliminer les risques associés à ces phénomènes dangereux :
a) instabilité de parties rigides de l’appareil de levage à charge suspendue ou de ses éléments (inclinaison,
déplacement) ;
b) dépassement des limites de résistance (élasticité, rupture, fatigue) ;
c) instabilité élastique de l’appareil de levage à charge suspendue ou de ses éléments (flambage, voilement) ;
d) dépassement des limites de température du matériau ou des composants ;
e) dépassement des limites de déformation.
La présente Norme européenne s'applique aux appareils de levage à charge suspendue construites après sa date
d'approbation par le CEN et sert de référence pour les normes européennes sur les types de grues particuliers.
Dvigala (žerjavi) - Konstruiranje, splošno - 1. del: Splošna načela in zahteve
Ta evropski standard je namenjen uporabi skupaj z drugim in tretjim delom, in kot taki opredeljujejo splošne pogoje, zahteve in metode za preprečevanje mehanskih nevarnosti pri dvigalih (žerjavih) z načrtovanjem in teoretičnim preverjanjem. Tretji del je šele v fazi predpriprave osnutka; uporaba prvega in drugega dela ni pogojena z objavo tretjega dela.
General Information
Relations
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Krane - Konstruktion allgemein - Teil 1: Allgemeine Prinzipien und AnforderungenAppareils de levage à charge suspendue - Conception générale - Partie 1: Principes généraux et prescriptionsCranes - General design - Part 1: General principles and requirements53.020.20DvigalaCranesICS:Ta slovenski standard je istoveten z:EN 13001-1:2004+A1:2009SIST EN 13001-1:2005+A1:2009en,fr01-junij-2009SIST EN 13001-1:2005+A1:2009SLOVENSKI
STANDARD
SIST EN 13001-1:2005+A1:2009
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 13001-1:2004+A1
April 2009 ICS 53.020.20 Supersedes EN 13001-1:2004English Version
Cranes - General design - Part 1: General principles and requirements
Appareils de levage à charge suspendue - Conception générale - Partie 1: Principes généraux et prescriptions
Krane - Konstruktion allgemein - Teil 1: Allgemeine Prinzipien und Anforderungen This European Standard was approved by CEN on 2 March 2004 and includes Corrigendum 1 issued by CEN on 12 November 2008 and Amendment 1 approved by CEN on 7 March 2009.
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. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN Management Centre or to any CEN member.
This European Standard exists 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.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2009 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 13001-1:2004+A1:2009: ESIST EN 13001-1:2005+A1:2009
EN 13001-1:2004+A1:2009 (E) 2 Contents Page Foreword . 3Introduction . 41Scope. 42Normative references . 43Terms, definitions, symbols and abbreviations . 53.1Terms and definitions . 53.2Symbols and abbreviations . 54Safety requirements and/or measures. 84.1General . 84.2Proof calculation . 84.2.1General principles . 84.2.2Models of cranes and loads . 104.2.3Simulation of load actions . 104.2.4Load combinations and load effects . 114.2.5Limit states . 114.2.6Proof of competence . 114.2.7Methods for the proof of competence . 124.3Classification . 144.3.1General . 144.3.2Total numbers of working cycles . 154.3.3Average linear or angular displacements. 154.3.4Frequencies of loads . 174.3.5Positioning of loads . 184.4Stress histories . 194.4.1General . 194.4.2Frequencies of stress cycles . 204.4.3Transformation of the identified stress cycles into cycles with constant mean stress or constant stress ratio . 214.4.4Classification of stress histories . 24Annex A (informative)
Selection of a suitable set of crane standards for a given application . 27Annex ZA (informative)
Relationship between this European
Standard and the Essential Requirements of EU Directive 98/37/EC . 28Annex ZB (informative)
!!!!Relationship between this European Standard and the Essential Requirements of EU Directive 2006/42/EC"""" . 29Bibliography . 30 SIST EN 13001-1:2005+A1:2009
EN 13001-1:2004+A1:2009 (E) 3 Foreword This document (EN 13001-1:2004+A1:2009) has been prepared by Technical Committee CEN/TC 147 “Cranes - Safety”, the secretariat of which is held by BSI. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by October 2009, and conflicting national standards shall be withdrawn at the latest by December 2009. This European Standard was approved by CEN on 2 March 2004 and includes Corrigendum 1 issued by CEN on 12 November 2008 and Amendment 1 approved by CEN on 7 March 2009. This document supersedes EN 13001-1:2004. The start and finish of text introduced or altered by amendment is indicated in the text by tags !". The modifications of the related CEN Corrigendum have been implemented at the appropriate places in the text and are indicated by the tags ˜ ™. !This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association, and supports essential requirements of EU Directive(s). For relationship with EU Directive(s), see informative Annexes ZA and ZB, which are integral parts of this document." Annex A is informative. This European Standard is one Part of EN 13001. The other parts are as follows: Part 1: General Principles and requirements Part 2: Load actions Part 3.1: Limit states and proof of competence of steel structures Part 3.2: Limit states and proof of competence of rope reeving components Part 3.3: Limit states and proof of competence of wheel/rail contacts Part 3.4: Limit states and proof of competence of machinery According to the CEN/CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Standard: 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.
SIST EN 13001-1:2005+A1:2009
EN 13001-1:2004+A1:2009 (E) 4 Introduction This European Standard has been prepared to be a harmonized standard to provide one means for the mechanical design and theoretical verification of cranes to conform with the essential health and safety requirements of the Machinery Directive, as amended. This standard also establishes interfaces between the user (purchaser) and the designer, as well as between the designer and the component manufacturer, in order to form a basis for selecting cranes and components. This European Standard is a type C standard as stated in EN 1070. The machinery concerned and the extent to which hazards are covered are indicated in the scope of this standard. When provisions of this type C standard are different from those, which are stated in type A or B standards, the provisions of this type C standard take precedence over the provisions of the other standards, for machines that have been designed and built according to the provisions of this type C standard. 1 Scope This European Standard is to be used together with Part 2 and Part 3, and as such, they specify general conditions, requirements and methods to prevent mechanical hazards of cranes by design and theoretical verification. Part 3 is only at pre-drafting stage; the use of Parts 1 and 2 is not conditional to the publication of Part 3. NOTE Specific requirements for particular types of crane are given in the appropriate European Standard for the particular crane type. The following is a list of significant hazardous situations and hazardous events that could result in risks to persons during normal use and foreseeable misuse. Clause 4 of this standard is necessary to reduce or eliminate the risks associated with the following hazards: a) rigid body instability of the crane or its parts (tilting, shifting); b) exceeding the limits of strength (yield, ultimate, fatigue); c) elastic instability of the crane or its parts (buckling, bulging); d) exceeding temperature limits of material or components; e) exceeding the deformation limits. This European Standard is applicable to cranes which are manufactured after the date of approval by CEN of this standard and serves as reference base for the European Standards for particular crane types. 2 Normative references This European Standard incorporates, by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any SIST EN 13001-1:2005+A1:2009
EN 13001-1:2004+A1:2009 (E) 5 of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies (including amendments). EN ISO 12100-1:2003, Safety of machinery — Basic concepts, general principles for design — Part 1: Basic terminology, methodology (ISO 12100-1:2003). EN ISO 12100-2:2003, Safety of machinery — Basic concepts, general principles for design — Part 2: Technical principles and specifications(ISO 12100-2:2003). EN 1070:1998, Safety of machinery — Terminology. ˜EN 1990:2002, Eurocode - Basis of structural design™ EN 13001-2, Cranes — General design — Part 2: Load actions. ISO 4306-1:1990, Cranes — Vocabulary — Part 1: General. 3 Terms, definitions, symbols and abbreviations 3.1 Terms and definitions For the purposes of this European Standard, the terms and definitions given in EN 1070:1998, EN 1990-1:2002 and clause 6 of ISO 4306-1:1990 apply. 3.2 Symbols and abbreviations For the purposes of this European Standard, the symbols and abbreviations given in Table 1 apply. Table 1 — Symbols and abbreviations Symbols, abbreviations Description σadm Allowable (admissible) stress C Total number of working cycles iC Number of working cycles where a load i is handled rC Number of working cycles of task r D Classes of average displacements X 0linDto 9linD Classes of average linear displacement linX
0angD to 5angD Classes of average angular displacement angX if Characteristic loads jF Combined loads from load combination j (limit state method) jF Combined loads from load combination j (allowable stress method) k Stress spectrum factor
SIST EN 13001-1:2005+A1:2009
EN 13001-1:2004+A1:2009 (E) 6 Table 1 (continued) Symbols, abbreviations Description kQ Load spectrum factor rkQ Load spectrum factor for task r Dlim Limit in damage calculation σlim Limit design stress m Inverse slope of the log aσ/log Ncurve nˆ Total number of stress cycles
ijn Number of stress cycles of class ij ()rnij Number of stress cycles of class ij occurring each time task r is carried out rjri,nn Service frequency of position i or j
n(R or mσ) Number of stress cycles with stress amplitude aσ(R or mσ) in(R or mσ) Number of stress cycles with amplitude ia,σ(R or mσ) N Number of stress cycles to failure by fatigue DN Number of cycles at reference point p Average number of accelerations P,0P to 3P Classes of average numbers of accelerations p 0Q to 5Q Classes of load spectrum factors kQ Q Maximum value of rQfor all tasks r iQ Magnitude of load i rQ Maximum load for task r dR Characteristic resistance of material, connection or component R Stress ratio s Stress history parameter S,0S, to 9S Classes of stress history parameters s kS Load effect in section k of a member (limit state method) kS Load effect in section k of a member (allowable stress method) 0,UU to 9U Classes of total numbers of working cycles C rjrixx, Displacement of the drive under consideration to serve position i or j
SIST EN 13001-1:2005+A1:2009
EN 13001-1:2004+A1:2009 (E) 7 Table 1 (concluded) Symbols, abbreviations Description rx Average displacement during task r X Average displacement anglinXX, Average linear or angular displacement 21,αα Angles between horizontal line and lines of constant N in the maσσ−plane rα Relative number of working cycles for task r fγ Overall safety factor mγ Resistance coefficient nγ Risk coefficient pγ Partial safety factor pγ Reduced partial safety factor µ, µ1, µ2 Rises of lines of constant N in the σa-σm-plane ν Relative total number of stress cycles σa Stress amplitude σa(R or σm) Stress amplitude for constant stress ratio R or constant mean stress σm a1ˆ(R or σm) Maximum stress amplitude for constant stress ratio R or constant mean stress σm σa,i Stress amplitude of range i σa,i (R or σm) Stress amplitude of range i for constant stress ratio or constant mean stress σb Lower extreme value of stress cycle lσ Design stress in element l (limit state method) l1 Design stress in element l (allowable stress method) l1σ Stresses in element l resulting from Sk (limit state method) l11 Stresses in element l resulting from kS (allowable stress method) l2σ Stresses in element l arising from local effects (limit state method) l21 Stresses in element l arising from local effects (allowable stress method) σm Mean stress σm,j Mean stress of range j σu Upper extreme value of stress cycle φi Dynamic factors
SIST EN 13001-1:2005+A1:2009
EN 13001-1:2004+A1:2009 (E) 8 4 Safety requirements and/or measures 4.1 General Machinery shall conform to the safety requirements and/or measures of this clause. Hazards not covered in EN 13001 may be covered by other general requirements for all types of cranes and/or by specific requirements for particular types of cranes, as given in the EN standards listed in annex A. In addition, the machine shall be designed according to the principles of ˜EN ISO™ 12100-1 and ˜EN ISO™ 12100-2 for hazards relevant but not significant which are not dealt with by the above mentioned standards. 4.2 Proof calculation 4.2.1 General principles The objective of this calculation is to prove theoretically that a crane, taking into account the service conditions agreed between the user, designer and/or manufacturer, as well as the states during erection, dismantling and transport, has been designed in conformance to the safety requirements to prevent mechanical hazards. The proof of competence according to EN 13001 shall be carried out by using the general principles and methods appropriate for this purpose and corresponding with the recognised state of the art in crane design. Alternatively, advanced and recognised theoretical or experimental methods may be used in general, provided that they conform to the principles of this standard. Hazards can occur if extreme values of load effects or their histories exceed the corresponding limit states. To prevent these hazards with a margin of safety, it shall be shown that the calculated extreme values of load effects from all loads acting simultaneously on a crane and multiplied with an adequate partial safety coefficient, as well as the estimated histories of load effects, do not exceed their corresponding limit states at any critical point of the crane. For this purpose the limit state method, and where applicable the allowable stress method, is used in accordance with international and European design codes. The analysis of load actions from individual events or representative use of a crane (representative load histories) is required to reflect realistic unfavourable operational conditions and sequences of actions of the crane. Figure 1 illustrates the general layout of a proof calculation for cranes.
SIST EN 13001-1:2005+A1:2009
EN 13001-1:2004+A1:2009 (E) 9
Key a) Models of crane and loads b) Load actions c)
Limit states d) Proof
Figure 1 — Layout of the proof calculation SIST EN 13001-1:2005+A1:2009
EN 13001-1:2004+A1:2009 (E) 10 4.2.2 Models of cranes and loads For the calculation of the movements, inner forces (torques in gears, rope forces, etc.) and losses of the crane or its parts, rigid body kinetic models are used. The loads acting on this model are the motor torques and/or brake torques, which have to balance any of the loads acting on the moved parts as losses, mass forces caused by gravity, movement of the crane or parts thereof, and wind forces. From this rigid body kinetic model of the crane and the load models, any variation of displacement, speed, acceleration and/or inner forces as well as the corresponding instantaneous values of acceleration and/or inner forces can be derived. These variations, if calculated in conformity with the agreed service conditions, are the base for estimating the histories of load effects (e. g. heat equivalents) and the stress histories. Since the variations and instantaneous values of accelerations and inner forces calculated by using a rigid body kinetic model only represent mean values of the real process, loads caused by sudden alterations of these mean values shall be amplified by dynamic factors φi to estimate their real values (see EN 13001-2). For cranes or crane configurations where all the loads from different drives acting simultaneously do not affect each other because they are acting at right angles to each other (i.e. orthogonal), load actions from drives can be considered independently. In cases where the loads from simultaneous actions of different drives affect each other (dependent, non-orthogonal), this shall be taken into account. The calculation of nominal stresses in any mechanical and/or structural component of a crane or its parts can commonly be based on appropriate elasto-static models, built up by beam or more sophisticated elements, such as plane stress, plate or shell elements. A nominal stress is a stress calculated in accordance with simple elastic strength of materials theory, excluding local stress concentration effects. 4.2.3 Simulation of load actions For the simulation of the time varying process of load actions on a crane or its parts, static equivalent loads from independent events occuring during the intended use of a crane shall be applied to elasto-static models, which correspond with the configuration and supporting conditions of the crane or its parts under consideration. NOTE In this context the term “load” or "load action" means any action or circumstance, which causes load effects in the crane or its parts, for example: forces, intended and non-intended displacements and/or movements, temperature, wind pressure. Static equivalent loads are given in EN 13001-2. These static equivalent loads are considered as deterministic actions, which have been adjusted in such a way that they represent load actions during the use of the crane from the actions or circumstances under consideration. The limit state method (see 4.2.7.1) does take into account the probabilistic nature of the loads, whereas the allowable stress method (see 4.2.7.2) does not. If a different level of safety is required in some instance, a risk factor γn may be agreed upon and applied. SIST EN 13001-1:2005+A1:2009
EN 13001-1:2004+A1:2009 (E) 11 4.2.4 Load combinations and load effects The loads shall be superimposed in such a way that the resulting load effects attain their instantaneous extreme values for the considered situation of use. Such superimpositions are called load combinations. Basic load combinations are given in EN 13001-2. When establishing the load combinations, consideration shall be given to the use of the crane, taking into account its control systems, its normative instructions for use, and any other inherent conditions, where they relate to the specific aim of the proof of competence. Magnitude, position and direction of all loads which act simultaneously in the sense of a load combination, shall be chosen in such a way that extreme load effects occur in the component or design detail under consideration. Consequently, in order to establish the extreme stresses in all the design critical points, several loading events or crane configurations shall be studied within the same load combination, e. g. different positions of a crab in a bridge or gantry crane. The upper and lower extreme values of the load effects , in terms of inner forces or nominal stresses, shall be used for a static proof calculation to avoid the hazards described in the scope. In combination with the agreed service conditions and the kinematic properties of the crane or its parts, these values limit the histories of inner forces or nominal stresses for the proof of fatigue strength. For the proof of fatigue strength, the number and magnitude of significant stress cycles shall be specified. 4.2.5 Limit states For the purposes of this standard limit states are states of the crane, its components or materials which, if exceeded, can result in the loss of the operational characteristics of the crane. There is a distinction between ultimate limit states and serviceability limit states as follows: a) Ultimate limit states, given by: 1) plastic deformations from the effect of nominal stresses or sliding of frictional connections; 2) failure of components or connections (e. g. static failure, failure by fatigue or formation of critical cracks); 3) elastic instability of the crane or its parts (e. g. buckling, bulging); 4) rigid body instability of the crane or its parts (e. g. tilting, shifting). b) Serviceability limit states, examples of which are: 1) deformations which impair the intended utilization of the crane (e. g. function of moving components, clearances of parts); 2) vibrations that cause damage to the crane driver or cause damage to the crane structure or restrict the ability to operate; 3) exceeding temperature limits (e. g. overheating of motors and brakes). 4.2.6 Proof of competence The limit states applicable to the combination of material selection, manufacturing techniques and the specified service conditions shall be stated in the proof of competence. For the verification that the ultimate limit states are not exceeded, the following proofs shall be established: SIST EN 13001-1:2005+A1:2009
EN 13001-1:2004+A1:2009 (E) 12 a) proof of strength of members, connections and components: 1) under static and quasi-static loading; 2) under cyclic loading (fatigue); b) proof of elastic stability of the crane and its parts; c) proof of rigid body stability. For the verification that the serviceability limit states are not exceeded, the following aspects shall be considered, and a proof be established where appropriate: a) proof of deformation; b) vibration; c) thermal performance. 4.2.7 Methods for the proof of competence 4.2.7.1 Limit state method For a general description of the limit state method, see ISO 2394:1998, General principles on reliability for structures. For all crane systems, the limit state method is applicable without any restriction. Individual characteristic loads fi shall be calculated and amplified where necessary using the factors φi, multiplied by the appropriate partial safety factors γp or reduced partial safety factors p and combined into Fj according to the load combination under consideration. When agreed upon Fj shall also be multiplied by an appropriate risk coefficient γn.
The result γn ⋅Fj shall be used to determine the resulting load effects Sk, i.e. the inner forces in structural or mechanical components or the forces in articulations and supports. For proof that yielding and elastic instability will not occur, the nominal design stresses σ1l due to the action of the loads on a particular component are calculated and combined with any stresses σ2l resulting from local effects, calculated using the appropriate partial safety factors γp and where agreed upon the risk coefficient γn. The resulting design stress σl shall be compared with the limit design stress lim σ. It is derived from the specific strength or characteristic resistance Rd of material, connection or component with at least 95 % probability of survival, divided by the resistance coefficient γm = 1,10. For the proof of rigid body stability it shall be shown that under the combined action of the loads multiplied by their partial safety factors no rigid body movement occurs. All supports, where given limits are exceeded, i.e. wheel/rail under tension or rope under compression, shall be neglected. This means that in the sense of the elasto-static model, the corresponding restraints shall be set “inactive”. The remaining positive and/or frictional support forces shall be sufficient to ensure the rigid body stability. A flow chart illustrating the limit state method for the proof calculation based on stresses is shown in Figure 2. For the proof based on forces, moments, deflections the limit state method shall be applied by analogy. SIST EN 13001-1:2005+A1:2009
EN 13001-1:2004+A1:2009 (E) 13
Key fi characteristic load i on the element component; Fj combined load from load combination j including φ- factors; Sk load effects in section k of members or supporting parts, such as inner forces and moments, resulting from load combination Fj; σ1l stresses in the particular elementl as a result of load effects Sk; σ2l stresses in the particular elementl arising from local effects; σl resulting design stress in the particular element l; Rd specified strength or characteristic resistance of the material, particular element or connection, such as the stress corresponding to the yield point, limit of elastic stability or fatigue strength (limit states); lim σ limit design stress; γp partial safety factors applied to individual loads according to the load
combination under consideration; γn risk coefficient, where applicable; γm resistance coefficient. Figure 2 — Typical flow chart of the limit state method 4.2.7.2 Allowable stress method For cranes of mass distribution class MDC1 (see EN 13001-2) with a linear relationship between load actions and load effects, the allowable stress method is applicable for the proof of competence calculation. The allowable stress method can also be used for portions of MDC2 systems that act in the same manner as a linear MDC1 system. The allowable stress method is a special case of the limit state method, where the partial safety factors are given the same value, which combined with the resistance coefficient, forms an overall safety factor γ f. Because of its special character, the allowable stress method is only reliable in specific cases. Individual specified loads fi shall be c
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