PREAMBLE (NOT PART OF THE STANDARD)

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EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM

EN 1999-1-4:2007/A1

August 2011

ICS 91.010.30; 91.080.10

English Version

Eurocode 9: Design of aluminium structures - Part 1-4: Cold-formed structural sheeting

Eurocode 9 - Calcul des structures en aluminium - Partie 14: Tôles de structure formées à froid Eurocode 9: Bemessung und Konstruktion von Aluminiumtragwerken - Teil 1-4: Kaltgeformte Profiltafeln

This amendment A1 modifies the European Standard EN 1999-1-4:2007; it was approved by CEN on 8 April 2011.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for inclusion of this amendment into the relevant national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This amendment 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-CENELEC Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, 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.

Image

Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2011 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members.

Ref. No. EN 1999-1-4:2007/A1:2011: E

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Contents

Page
Foreword 4
National Annex for EN 1999-1-4 6
1 General 7
  1.1 Scope 7
    1.1.1 Scope of EN 1999 7
    1.1.2 Scope of EN 1999-1-4 7
  1.2 Normative references 8
    1.2.1 General references 8
    1.2.2 References on structural design 8
    1.2.3 Materials and materials testing 8
    1.2.4 References on fasteners 8
    1.2.5 Other references 8
  1.3 Terms and definitions 9
  1.4 Symbols 10
  1.5 Geometry and conventions for dimensions 10
    1.5.1 Form of sections 10
    1.5.2 Form of stiffeners 10
    1.5.3 Cross-section dimensions 11
    1.5.4 Convention for member axis 11
2 Basis of design 12
3 Materials 13
  3.1 General 13
  3.2 Structural aluminium alloys 13
    3.2.1 Material properties 13
    3.2.2 Thickness and geometrical tolerances 14
  3.3 Mechanical fasteners 15
4 Durability 15
5 Structural analysis 16
  5.1 Influence of rounded corners 16
  5.2 Geometrical proportions 17
  5.3 Structural modelling for analysis 17
  5.4 Flange curling 18
  5.5 Local and distortional buckling 19
    5.5.1 General 19
    5.5.2 Plane cross-section parts without stiffeners 19
    5.5.3 Plane cross-section parts with intermediate stiffeners 20
    5.5.4 Trapezoidal sheeting profiles with intermediate stiffeners 24
6 Ultimate limit states 31
  6.1 Resistance of cross-sections 31
    6.1.1 General 31
    6.1.2 Axial tension 31
    6.1.3 Axial compression 31
    6.1.4 Bending moment 32
    6.1.5 Shear force 34
    6.1.6 Torsion 35
    6.1.7 Local transverse forces 35
    6.1.8 Combined tension and bending 38
    6.1.9 Combined compression and bending 39
    6.1.10 Combined shear force, axial force and bending moment 39
    6.1.11 Combined bending moment and local load or support reaction 40 2
  6.2 Buckling resistance 40
    6.2.1 General 40
    6.2.2 Axial compression 41
    6.2.3 Bending and axial compression 41
  6.3 Stressed skin design 42
    6.3.1 General 42
    6.3.2 Diaphragm action 42
    6.3.3 Necessary conditions 43
    6.3.4 Profiled aluminium sheet diaphragms 44
  6.4 Perforated sheeting with the holes arranged in the shape of equilateral triangles 45
7 Serviceability limit states 46
  7.1 General 46
  7.2 Plastic deformation 46
  7.3 Deflections 46
8 Joints with mechanical fasteners 47
  8.1 General 47
  8.2 Blind rivets 48
    8.2.1 General 48
    8.2.2 Design resistances of riveted joints loaded in shear 48
    8.2.3 Design resistances for riveted joints loaded in tension 48
  8.3 Self-tapping / self-drilling screws 49
    8.3.1 General 49
    8.3.2 Design resistance of screwed joints loaded in shear 49
    8.3.3 Design resistance of screwed joints loaded in tension 50
9 Design assisted by testing 52
Annex A [normative] – Testing procedures 53
  A.1 General 53
  A.2 Tests on profiled sheets 53
    A.2.1 General 53
    A.2.2 Single span test 54
    A.2.3 Double span test 54
    A.2.4 Internal support test 54
    A.2.5 End support test 56
  A.3 Evaluation of test results 57
    A.3.1 General 57
    A.3.2 Adjustment of test results 57
    A.3.3 Characteristic values 58
    A.3.4 Design values 59
    A.3.5 Serviceability 59
Annex B [informative] – Durability of fasteners 60
Bibliography 62
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Foreword

This European Standard (EN 1999-1-4:2007) has been prepared by Technical Committee CEN/TC250 « Structural Eurocodes », the secretariat of which is held by BS1.

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 August 2007, and conflicting national standards shall be withdrawn at the latest by March 2010.

This European Standard supersedes ENV 1999-1-1:1998, ENV 1999-1-2:1998 and ENV 1999-2:1998.

CEN/TC 250 is responsible for all Structural Eurocodes.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard:

Austria, Bulgaria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italia, Latvia, Lithuania, Luxemburg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom

Background of the Eurocode programme

In 1975, the Commission of the European Community decided on an action programme in the field of construction, based on article 95 of the Treaty. The objective of the programme was the elimination of technical obstacles to trade and the harmonisation of technical specifications.

Within this action programme, the Commission took the initiative to establish a set of harmonised technical rules for the design of construction works, which, in a first stage, would serve as an alternative to the national rules in force in the Member States and, ultimately, would replace them.

For fifteen years, the Commission, with the help of a Steering Committee with Representatives of Member States, conducted the development of the Eurocodes programme, which led to the first generation of European codes in the 1980s.

In 1989, the Commission and the Member States of the EU and EFTA decided, on the basis of an agreement1 between the Commission and CEN, to transfer the preparation and the publication of the Eurocodes to the CEN through a series of Mandates, in order to provide them with a future status of European Standard (EN). This links de facto the Eurocodes with the provisions of all the Council’s Directives and/or Commission’s Decisions dealing with European standards (e.g. the Council Directive 89/106/EEC on construction products - CPD - and Council Directives 93/37/EEC, 92/50/EEC and 89/440/EEC on public works and services and equivalent EFTA Directives initiated in pursuit of setting up the internal market).

The Structural Eurocode programme comprises the following standards generally consisting of a number of Parts:

EN 1990 Eurocode 0: Basis of Structural Design
EN 1991 Eurocode 1: Actions on structures
EN 1992 Eurocode 2: Design of concrete structures
EN 1993 Eurocode 3: Design of steel structures
EN 1994 Eurocode 4: Design of composite steel and concrete structures
EN 1995 Eurocode 5: Design of timber structures
EN 1996 Eurocode 6: Design of masonry structures
EN 1997 Eurocode 7: Geotechnical design
EN 1998 Eurocode 8: Design of structures for earthquake resistance
EN 1999 Eurocode 9: Design of aluminium structures

1 Agreement between the Commission of the European Communities and the European Committee for Standardisation (CEN) concerning the work on EUROCODES for the design of building and civil engineering works (BC/CEN/03/89).

4

Eurocode standards recognise the responsibility of regulatory authorities in each Member State and have safeguarded their right to determine values related to regulatory safety matters at national level where these continue to vary from State to State.

Status and field of application of Eurocodes

The Member States of the EU and EFTA recognise that Eurocodes serve as reference documents for the following purposes:

The Eurocodes, as far as they concern the construction works themselves, have a direct relationship with the Interpretative Documents2 referred to in Article 12 of the CPD, although they are of a different nature from harmonised product standards3. Therefore, technical aspects arising from the Eurocodes work need to be adequately considered by CEN Technical Committees and/or EOTA Working Groups working on product standards with a view to achieving full compatibility of these technical specifications with the Eurocodes.

The Eurocode standards provide common structural design rules for everyday use for the design of whole structures and component products of both a traditional and an innovative nature. Unusual forms of construction or design conditions are not specifically covered and additional expert consideration will be required by the designer in such cases.

National standards implementing Eurocodes

The National Standards implementing Eurocodes will comprise the full text of the Eurocode (including any annexes), as published by CEN, which may be preceded by a National title page and National foreword, and may be followed by a National annex [informative].

The National Annex (informative) may only contain information on those parameters which are left open in the Eurocode for national choice, known as Nationally Determined Parameters, to be used for the design of buildings and civil engineering works to be constructed in the country concerned, i.e.:

Links between Eurocodes and harmonised technical specifications (EN’s and ETA’s) for products

There is a need for consistency between the harmonised technical specifications for construction products and the technical rules for works4. Furthermore, all the information accompanying the CE Marking of the

2 According to Art. 3.3 of the CPD, the essential requirements (ERs) shall be given concrete form in interpretative documents for the creation of the necessary links between the essential requirements and the mandates for harmonised ENs and ETAGs/ETAs.

3 According to Art. 12 of the CPD the interpretative documents shall:

  1. give concrete from to the essential requirements by harmonising the terminology and the technical bases and indicating classes or levels for each requirement where necessary;
  2. indicate methods of correlating these classes or levels of requirement with the technical specifications, e.g. methods of calculation and of proof, technical rule: for project design, etc.;
  3. serve as a reference for the establishment of harmonised standards and guidelines for European technical approvals.

The Eurocodes, de facto, play a similar role in the field of the ER 1 and a part of ER 2.

4 see Art.3.3 and Art. 12 of the CPD, as well clauses 4.2, 4.3.1, 4.3.2 and 5.2 of ID 1.

5

construction products which refer to Eurocodes shall clearly mention which Nationally Determined Parameters have been taken into account.

Foreword to amendment A1

This document (EN 1999-1 -4:2007/A1:2011) has been prepared by Technical Committee CEN/TC 250 “Structural Eurocodes”, the secretariat of which is held by BSI.

This Amendment to the European Standard EN 1999-1-4:2007 shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by August 2012, and conflicting national standards shall be withdrawn at the latest by August 2012.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, 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 the United Kingdom.

National Annex for EN 1999-1-4

This standard gives alternative procedures, values and recommendations for classes with notes indicating where national choices may have to be made. Therefore the National Standard implementing EN 1999-1 -4 should have a National Annex containing all Nationally Determined Parameters to be used for the design of aluminium structures to be constructed in the relevant country.

National choice is allowed in EN 1999-1-4 through clauses:

6

1 General

1.1 Scope

1.1.1 Scope of EN 1999

  1. P EN 1999 applies to the design of buildings and civil engineering and structural works in aluminium. It complies with the principles and requirements for the safety and serviceability of structures, the basis of their design and verification that are given in EN 1990 – Basis of structural design.
  2. EN 1999 is only concerned with requirements for resistance, serviceability, durability and fire resistance of aluminium structures. Other requirements, e.g. concerning thermal or sound insulation, are not considered.
  3. EN 1999 is intended to be used in conjunction with:
  4. EN 1999 is subdivided in five parts:
    EN 1999-1-1 Design of Aluminium Structures: General structural rules.
    EN 1999-1-2 Design of Aluminium Structures: Structural fire design.
    EN 1999-1-3 Design of Aluminium Structures: Structures susceptible to fatigue.
    EN 1999-1-4 Design of Aluminium Structures: Cold-formed structural sheeting.
    EN 1999-1-5 Design of Aluminium Structures: Shell structures.

1.1.2 Scope of EN 1999-1-4

  1. P EN 1999-1-4 gives design requirements for cold-formed trapezoidal aluminium sheeting. It applies to cold-formed aluminium products made from hot rolled or cold rolled sheet or strip that have been cold-formed by such processes as cold-rolled forming or press-breaking. The execution of aluminium structures made of cold-formed sheeting is covered in EN 1090-3.

    NOTE The rules in this part complement the rules in other parts of EN 1999-1.

  2. Methods are also given for stressed-skin design using aluminium sheeting as a structural diaphragm.
  3. This part does not apply to cold-formed aluminium profiles like C-, Z- etc profiles nor cold-formed and welded circular or rectangular hollow sections.
  4. EN 1999-1-4 gives methods for design by calculation and for design assisted by testing. The methods for the design by calculation apply only within stated ranges of material properties and geometrical properties for which sufficient experience and test evidence is available. These limitations do not apply to design by testing.
  5. EN 1999-1-4 does not cover load arrangement for loads during execution and maintenance.

5 To be published

7

1.2 Normative references

  1. 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.

1.2.1 General references

EN 1090-1: Execution of steel structures and aluminium structures – Part 1: Requirements for conformity assessment of structural components6
EN 1090-3: Execution of steel structures and aluminium structures – Part 3: Technical requirements for aluminium structures6

1.2.2 References on structural design

EN 1990 Eurocode 0 - Basis of structural design
EN 1991 Eurocode 1 – Action on structures – All parts
EN 1995-1-1 Eurocode 5: Design of timber structures - Part 1-1 General rules and rules for buildings
EN 1999-1-1 Eurocode 9: Design of aluminium structures - Part 1-1 General structural rules

1.2.3 Materials and materials testing

Image EN 485-2:2008 Image Aluminium and aluminium alloys - Sheet, strip and plate - Part 2: Mechanical properties
Image EN 508-2 Image Roofing products from metal sheet - Specification for self-supporting products of steel, aluminium or stainless steel sheet - Part 2: Aluminium
Image EN 1396:2007 Image Aluminium and aluminium alloys - Coil coated sheet and strip for general applications - Specifications
EN 10002-1 Metallic materials - Tensile testing - Part 1: Method of test at ambient temperature
Image Text deleted Image  

1.2.4 References on fasteners

EN ISO 1479 Hexagon head tapping screws
EN ISO 1481 Slotted pan head tapping screws
EN ISO 15480 Hexagon washer head drilling screws with tapping screw thread
EN ISO 15481 Cross recessed pan head drilling screws with tapping screw thread
EN ISO 15973 Closed end blind rivets with break pull mandrel and protruding head
EN ISO 15974 Closed end blind rivets with break pull mandrel and countersunk head
EN ISO 15977 Open end blind rivets with break pull mandrel and protruding head
EN ISO 15978 Open end blind rivets with break pull mandrel and countersunk head
EN ISO 15981 Open end blind rivets with break pull mandrel and protruding head
EN ISO 15982 Open end blind rivets with break pull mandrel and countersunk head
ISO 7049:1994 Cross recessed pan head tapping screws

1.2.5 Other references

EN ISO 12944-2 Paints and varnishes - Corrosion protection of steel structures by protective paint systems - Part 2: Classification of environments

6 To be published

8

1.3 Terms and definitions

Supplementary to EN 1999-1-1, for the purposes of EN 1999-1-4, the following definitions apply:

1.3.1
base material

the flat sheet aluminium material out of which profiled sheets are made by cold forming

1.3.2
proof strength of base material

the 0,2 % proof strength fo of the base material

1.3.3
diaphragm action

structural behaviour involving in-plane shear in the sheeting

1.3.4
partial restraint

restriction to some extent of the lateral or rotational displacement of a cross-section part, that increases its buckling resistance

1.3.5
restraint

full restriction of the lateral displacement or rotational movement of a plane cross-section part, that increases its buckling resistance

1.3.6
slenderness parameter

a normalised, material related slenderness ratio

1.3.7
stressed-skin design

a design method that allows for the contribution made by diaphragm action in the sheeting to the stiffness and strength of a structure

1.3.8
support

a location at which a member is able to transfer forces or moments to a foundation, or to another structural component.

1.3.9
effective thickness

a design value of the thickness to allow for local buckling of plane cross section part.

1.3.10
reduced effective thickness

a design value of the thickness to allow for distortional buckling of stiffeners in a second step of the calculation procedure for plane cross section parts, where local buckling is allowed for in the first step.

9

1.4 Symbols

  1. In addition to those given in EN 1999-1-1, the following main symbols are used:

    Section 1 to 6

    C rotational spring stiffness;
    k linear spring stiffness;
    θ rotation;
    bp notional flat width of plane cross-section part;
    hw web height, measured between system lines of flanges;
    sw slant height of web, measured between midpoints of comers;
    χd reduction factor for distortional buckling (flexural buckling of stiffeners);
    φ is the angle between two plane elements;
    ϕ is the slope of the web relative to the flanges.

    Section 8 Joints with mechanical fasteners

    dw diameter of the washer or the head of the fastener;
    fu,min minor ultimate tensile strength of both connected parts;
    fu,sup ultimate tensile strength of the supporting component into which a screw is fixed;
    fy yield strength of supporting component of steel;
    tmin thickness of the thinner connected part or sheet;
    tsup thickness of the supporting member in which the screw is fixed;
  2. Further symbols arc defined where they first occur.

1.5 Geometry and conventions for dimensions

1.5.1 Form of sections

  1. Cold-formed sheets have within the permitted tolerances a constant thickness nominal over their entire length and have a uniform cross-section along their length.
  2. The cross-sections of cold formed profiled sheets essentially comprise a number of plane cross-section parts joined by curved parts.
  3. Typical forms of cross-sections for cold formed profiled sheets are shown in Figure 1.1.
  4. Cross-sections of cold formed sheets can either be unstiffened or incorporate longitudinal stiffeners in their webs or flanges, or in both.

1.5.2 Form of stiffeners

  1. Typical forms of stiffeners for cold formed sheets are shown in Figure 1.2; 10

    Figure 1.1 - Examples of cold-formed sheeting

    Figure 1.1 - Examples of cold-formed sheeting

    Figure 1.2 - Typical intermediate longitudinal stiffeners

    Figure 1.2 - Typical intermediate longitudinal stiffeners

1.5.3 Cross-section dimensions

  1. Overall dimensions of cold-formed sheeting, including overall width b, overall height h, internal bend radius r and other external dimensions denoted by symbols without subscripts, are measured to the outer contour of the section, unless stated otherwise, see Figure 5.1.
  2. Unless stated otherwise, the other cross-sectional dimensions of cold-formed sheeting, denoted by symbols with subscripts, such as bp, hw or sw, are measured either to the midline of the material or the midpoint of the corner.
  3. In the case of sloping webs of cold-formed profiled sheets, the slant height s is measured parallel to the slope.
  4. The developed height of a web is measured along its midline, including any web stiffeners.
  5. The developed width of a flange is measured along its midline, including any intermediate stiffeners.
  6. The thickness t is an aluminium design thickness if not otherwise stated. Sec 3.2.2.

1.5.4 Convention for member axis

  1. For profiled sheets the following axis convention is used in EN 1999-1-4:
11

2 Basis of design

  1. P The design of cold-formed sheeting shall be in accordance with the general rules given in EN 1990 and EN 1999-1-1.
  2. P Appropriate partial factors shall be adopted for ultimate limit states and serviceability limit states.
  3. For verification by calculation at ultimate limit states the partial factor γM shall be taken as follows:
    - resistance of cross-sections and members to instability: γM1
    - resistance of cross-sections in tension to fracture: γM2
    - resistance of joints: γM3

    NOTE Numerical values for γMi may be defined in the National Annex. The following numerical values are recommended for buildings:

    γM1 = 1,10

    γM2 = 1,25

    γM3 = 1,25

  4. For verifications at serviceability limit states the partial factor γM,ser should be used.

    NOTE Numerical values for γM,ser may be defined in the National Annex. The following numerical value is recommended for buildings:

    γM,ser = 1,0.

  5. For the design of structures made of cold-formed sheeting a distinction should be made between “Structural Classes” dependent on its function in the structure defined as follows:
    Structural Class I: Construction where cold-formed sheeting is designed to contribute to the overall strength and stability of the structure, see 6.3.3;
    Structural Class II: Construction where cold-formed sheeting is designed to contribute to the strength and stability of individual structural components;
    Structural Class III: Construction where cold-formed sheeting is used as a component that only transfers loads to the structure.

    NOTE 1 National Annex may give rules for the use of Structural Classes and the connection to Consequence Classes in EN 1990.

    NOTE 2 For Structural Class I and II the requirement for execution should be given in the execution specification, see EN 1090-3

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3 Materials

3.1 General

  1. The methods for design by calculation given in EN 1999-1-4 may be used for the structural alloys in the tempers listed in table 3.1.
  2. For design by calculation given in EN 1999-1-4 the 0,2 proof strength fo should be at least fo = 165 N/mm2.
  3. Aluminium sheet and strip used for cold-formed profile sheeting should be suitable for the specific cross section depending on cold forming and cold forming process.

    NOTE For other aluminium materials and products see National Annex.

3.2 Structural aluminium alloys

3.2.1 Material properties

  1. The characteristic values of 0,2 proof strength fo and tensile strength fu have been obtained by adopting the values for minimum Rp0,2 and Rm direct from the relevant product standards.
  2. It may be assumed that the properties in compression are the same as those in tension.
  3. If partially plastic moment resistance is utilised, the ratio of the characteristic ultimate tensile strength fu to the characteristic 0,2 proof strength fo should be not less than 1,2.
  4. The material constants (modulus of elasticity etc) should be taken as given in EN 1999-1 -1. 13
    Table 3.1 - Characteristic values of 0,2% proof strength fo, ultimate tensile strength, fu, elongation A50, for sheet and strip for tempers with fo > 165 N/mm2 and thickness between 0,5 and 6 mm
    Designation numerical EN AW- Designation chemical EN AW- Durability rating 5) Temper 1), 2), 3) Thickness up to mm fu Rm N/mm2 fo Rp0,2 1) N/mm2 A50 % 4)
    3003 AlMn1Cu A H18 3,0 190 170 2
    H48 3,0 180 165 2
    3004 AlMn1Mg1 A H14 | H24/H34 6 | 3 220 180 | 170 2-3 | 4
    H16 | H26/H36 4 | 3 240 200| 190 1-2 | 3
    H18 | H28/H38 3 | 1,5 260 230|220 1-2 | 3
    H44 3 210 180 4
    H46 3 230 200 3
    H48 3 260 220 3
    3005 AlMn1Mg0,5 A H16 4 195 175 2
    H18 | H28 3 220 200 | 190 2 | 2-3
    H48 3 210 180 2
    3103 AlMn1 A H18 3 185 165 2
    3105 AlMn0,5Mg0,5 A H18 | H28 3 | 1,5 195 180 | 170 1 | 2
    H48 3 195 170 2
    5005 AlMg1(B) A H18 3 185 165 2
    5052 AlMg2,5 A H14 6 230 180 3-4
    H16 | H26/H36 6 250 210 | 180 3 | 4-6
    H18 | H28/H38 3 270 240 | 210 2 | 3-4
    H46 3 250 180 4-5
    H48 3 270 210 3-4
    5251 Image AlMg2Mn0,3 Image A H14 6 210 170 2-4
    H16 | H26/H36 4 230 200 | 170 2-3 | 4-7
    H18 | H28/H38 3 255 230 | 200 2 | 3
    H46 3 210 165 4-5
    H48 3 250 215 3
    Image 6025-7072 alclad6) AlMg2,5SiMnCuAlZnl alclad6) A H34 5 210 165 2-3
    H36 5 220 185 2-4 Image
    1) The values for temper H1x, H2x, H3x according to Image EN 485-2:2008 Image

    2) The values for temper H4x (coil coated sheet and strip) according Image EN 1396:2007 Image

    3) If two (three) tempers are specified in one line, tempers separated by “|” have different technological values, but separated by “/” have same values. (The tempers show differences only for fo and A50.)

    4) A50 may be depending on the thickness of material in the listed range, therefore sometimes also a A50- range is given.

    5) Durability rating, see EN 1999-1-1

    Image 6) EN AW-6025-7072 alclad (EN AW-AlMg2,5SiMnCu-AlZnl alclad) is a composite material with core material EN AW-6025 and a cladding on both sides with EN AW-7072. For reasons of durability the cladding should have a thickness of at least 4% of the overall thickness of the material on each side. If the thickness of the cladding exceeds 5% this fact should be considered in the structural calculations, i.e. only the core thickness of the composite sheet should be taken in account. For these reasons the minimum cladding thickness of 4% and the minimum core thickness should be specified in the execution specification in order that the constructor can procure the corresponding constituent products with inspection certificate 3.1. Image

14

3.2.2 Thickness and geometrical tolerances

  1. The provisions for design by calculation given in this EN 1999-1-4 may be used for alloy within the following ranges of nominal thickness tnom of the sheeting exclusive of organic coatings:

    tnom ≥ 0,5 mm

  2. The nominal thickness tnom should be used as design thickness t if a negative deviation is less than 5 %. Otherwise

    t = tnom (100 − dev) / 95     (3.1)

    where dev is the negative deviation in %.

  3. Tolerances for roofing products are given in EN 508-2.

3.3 Mechanical fasteners

  1. The following types of mechanical fasteners may be used:
  2. The characteristic shear resistance Fv,Rk and the characteristic tension resistance Ft,Rk of the mechanical fasteners should be calculated according to 8.2 and 8.3.
  3. For details concerning suitable self-tapping screws, and self-drilling screws and blind rivets, reference should be made to EN 1090-3.
  4. Characteristic shear resistance and characteristic tension resistance of mechanical fasteners not covered in this European Standard may be taken from ETA certifications.

4 Durability

  1. For basic requirements, see Section 4 of EN 1999-1-1
  2. Special attention should be given to cases in which different materials are intended to act compositely, if these materials are such that electrochemical phenomena might produce conditions leading to corrosion.

    NOTE For corrosion resistance of fasteners for the environmental corrosivity categories following EN ISO 12944-2, see Annex B.

  3. The environmental conditions prevailing from the time of manufacture, including those during transport and storage on site, should be taken into account.
15

5 Structural analysis

5.1 Influence of rounded corners

  1. In cross-sections with rounded corners, the notional flat widths bp of the plane cross-section parts should be measured from the midpoints of the adjacent corner cross-section parts, as indicated in Figure 5.1.
  2. In cross-sections with rounded corners, the calculation of section properties should be based upon the actual geometry of the cross-section.
  3. Unless more appropriate methods are used to determine the section properties the following approximate procedure may be used. The influence of rounded corners on section properties may be neglected if the internal radius r ≤ 10t and r ≤ 0,15bp and the cross-section may be assumed to consist of plane cross-section parts with sharp corners.
  4. The influence of rounded corners on section properties may be taken into account by reducing the properties calculated for an otherwise similar cross-section with sharp corners, using the following approximations:

    AgAg,sh (1 − δ)     (5.1a)

    IgIg,sh (1 − 2δ)     (5.1b)

    with:

    Image

    where:

    Ag is the area of the gross cross-section;
    Ag,sh is the value of Ag for a cross-section with sharp corners;
    bp,i is the notional flat width of plane cross-section part i for a cross-section with sharp corners;
    Ig is the second moment of area of the gross cross-section;
    Ig,sh is the value of Ig for a cross-section with sharp corners;
    φ is the angle between two plane elements;
    m is the number of plane cross-section parts;
    n is the number of curved cross-section parts without consideration of the curvature of stiffeners in webs and flanges;
    rj is the internal radius of curved cross-section part.
  5. The reductions given by expression (5.1) may also be applied in calculating the effective section properties Aeff and Iy,eff provided that the notional flat widths of the plane cross-section parts are measured to the points of intersection of their midlines.
  6. Where the internal radius r ≥ 0,04tE / fo, then the resistance of the cross-section should be determined by tests. 16

    Figure 5.1 - Notional widths of plane cross-section parts bp allowing for corner radii

    Figure 5.1 - Notional widths of plane cross-section parts bp allowing for corner radii

5.2 Geometrical proportions

  1. The provisions for design by calculation given in EN 1999-1-4 should not be applied to cross-sections outside the range of width-to-thickness ratios b / t and sw / t given in (2).
  2. The maximum width-to-thickness ratios are:
    for compressed flanges b / t ≤ 300
    for webs sw / t0,5 E / fo

    NOTE These limits b / t and sw / t given in (2) may be assumed to represent the field for which sufficient experience and verification by testing is available. Cross-sections with larger width-to-thickness ratios may also be used, provided that their resistance at ultimate limit states and their behaviour at serviceability limit states are verified by testing and/or by calculations, where the results are confirmed by an appropriate number of tests.

5.3 Structural modelling for analysis

  1. The parts of a cross-section may be modelled for analysis as indicated in Table 5.1
  2. The mutual influence of multiple stiffeners should be taken into account. 17
    Table 5.1 - Modelling of parts of a cross-section
    Type of cross-section part Model Type of cross-section part Model
    Image Image Image Image
    Image Image Image Image

5.4 Flange curling

  1. The effect on the load bearing resistance of curling (i.e. inward curvature towards the neutral plane) of a very wide flange in a profile subject to flexure, or of an initially curved profile subject to flexure in which the concave side is in compression, should be taken into account unless such curling is less than 5 % of the depth of the profile cross-section. If curling is larger, then the reduction in load bearing resistance, for instance due to decrease in length of the lever arm for part of the wide flange, and to the possible effect of bending should be taken into account.

    Figure 5.2 - Flange curling

    Figure 5.2 - Flange curling

  2. Calculation of the curling may be carried out as follows. The formulae apply to both compression and tensile flanges, both with and without stiffeners, but without closely spaced transverse stiffeners in flanges.

    where:

    u is bending of the flange towards the neutral axis (curling), see Figure 5.2;
    bs is half the distance between the webs;
    z is distance of flange under consideration from neutral axis;
    r is radius of curvature of initially curved profile;
    σa is mean stress in the flange calculated with the gross area. If the stress is calculated for the effective cross-section, the mean stress is obtained by multiplying the stress for the effective cross-section by the ratio of the effective flange area to the gross flange area.
18

5.5 Local and distortional buckling

5.5.1 General

  1. The effects of local and distortional buckling should be taken into account in determining the resistance and stiffness of cold-formed sheeting.
  2. Local buckling effects may be considered by using effective cross-sectional properties, calculated on the basis of the effective thickness, see EN 1999-1-1.
  3. In determining resistance to local buckling, the 0,2 proof strength fo should be used.
  4. For effective cross-section properties for serviceability verifications, see 7.1 (3)
  5. The distortional buckling of cross-section parts with intermediate stiffeners is considered in 5.5.3.

5.5.2 Plane cross-section parts without stiffeners

  1. The effective thickness teff of compression cross-section parts should be obtained as teff = ρ · t, where ρ is a reduction factor allowing for local buckling.
  2. The notional flat width bp of a plane cross-section part should be determined as specified in 5.1. In the case of plane cross-section parts in a sloping web, the appropriate slant height should be used.
  3. The reduction factor ρ to determine teff should be based on the largest compressive stress σcom,Ed relevant cross-section part (calculated on the basis of the effective cross-section), when the resistance of the cross-section is reached.
  4. If σcom,Ed = f0 / γM1 the reduction factor ρ should be obtained from the following:

    Image

    Image

    in which the plate slenderness Image is given by:

    Image

    kσ is the relevant buckling factor from Table 5.3. The parameters Image and α may be taken from Table 5.2.

    Table 5.2 - Parameters λlim and α
    Image α
    0,517 0,90
  5. If σcom,Ed < fo / γM1 the reduction factor ρ may be determined as follows:

    Use expressions (5.2a) and (5.2b) but replace the plate slenderness Image by the reduced plate slenderness Image given by:

    19

    Image

  6. For calculation of effective stiffness at serviceability limit states, see 7.1(3)
  7. In determining the effective thickness of a flange cross-section part subject to stress gradient, the stress ratio ψ used in Table 5.3 may be based on the properties of the gross cross-section.
  8. In determining the effective thickness of a web cross-section part the stress ratio ψ used in Table 5.3 may be obtained using the effective area of the compression flange but the gross area of the web.
  9. Optionally the effective section properties may be refined by repeating (6) and (7) iteratively, but using the effective cross-section already found in place of the gross cross-section. The minimum steps in the iteration dealing with stress gradient are two.
    Table 5.3 - Buckling coefficient kσ for cross-section parts in compression
    Cross-section part (+ = compression) ψ = σ2 / σ1 Buckling factor kσ
    Image ψ = + 1 kσ = 4,0
    Image + 1 > ψ ≥ 0 Image
    Image 0 > ψ ≥ −1 kσ = 7,81 − 6,26ψ + 9,78ψ2
    Image −1 > ψ ≥ −3 kσ = 5,98(1 − ψ)2

5.5.3 Plane cross-section parts with intermediate stiffeners

5.5.3.1 General
  1. The design of compression cross-section parts with intermediate stiffeners should be based on the assumption that the stiffener behaves as a compression member with continuous partial restraint, with a spring stiffness that depends on the boundary conditions and the flexural stiffness of the adjacent plane cross-section parts.
  2. The spring stiffness of a stiffener should be determined by applying a unit load per unit length u as illustrated in Figure 5.3. The spring stiffness k per unit length may be determined from:

    k = u / δ     (5.5)

    where δ is the deflection of a transverse plate strip due to the unit load u acting at the centroid (b1) of the effective part of the stiffener.

    20

    Figure 5.3 - Model for determination of spring stiffness

    Figure 5.3 - Model for determination of spring stiffness

  3. In determining the values of the rotational spring stiffness Cθ,1 and Cθ,2 from the geometry of the cross-section, account should be taken of the possible effects of other stiffeners that exist on the same cross-section part, or on any other parts of the cross-section that is subject to compression.
  4. For an intermediate stiffener, as a conservative alternative, the values of the rotational spring stiffnesses Cθ,1 and Cθ,2 may be taken as equal to zero, and the deflection δ may be obtained from:

    Image

  5. The reduction factor χd distortional buckling resistance of a stiffener (flexural buckling of an intermediate stiffener) should be obtained from Table 5.4 for the slenderness parameter given in (5.7)

    Image

    where: σcr,s is the elastic critical stress for the stiffener from 5.5.3.3 or 5.5.4.2.

    Table 5.4 - Reduction factory χd for distortional buckling of stiffeners
    Image χd
    Image ≤ 0,25 1,00
    0,25 < Image < 1,04 1,155 − 0,62 Image
    1,04 ≤ Image 0,53/Image
5.5.3.2 Condition for use of the design procedure
  1. The following procedure is applicable to one or two equal intermediate stiffeners formed by grooves or bends provided that all plane parts are calculated according to 5.5.2.
  2. The stiffeners should be equally shaped and not more than two in number. For more stiffeners not more than two should be taken into account.
  3. If the criteria in (1) and (2) are met the effectiveness of the stiffener may be determined from the design procedure given in 5.5.3.3.
21
5.5.3.3 Design procedure
  1. The cross-section of an intermediate stiffener should be taken as comprising the stiffener itself plus the adjacent effective portions of the adjacent plane cross-section parts bp,1 and bp,2 shown in Figure 5.4.

    Figure 5.4 – Initial effective cross-section area As for intermediate stiffeners in (a) flange and (b) web

    Figure 5.4 – Initial effective cross-section area As for intermediate stiffeners in (a) flange and (b) web

  2. The procedure, which is illustrated in Figure 5.5, should be earned out in steps as follows: 22

    Figure 5.5 – Model for calculation of compression resistance of a flange with intermediate stiffener

    Figure 5.5 – Model for calculation of compression resistance of a flange with intermediate stiffener

  3. Initial values of the effective thickness teff,1 and teff,2 shown in Figure 5.4 should be determined from 5.5.2 by assuming that the plane cross-section parts bp,1 and bp,2 are doubly supported, see Table 5.1.
  4. The effective cross-sectional area of an intermediate stiffener As should be obtained from:

    As = teff,1 bp,1 / 2 + t bs + teff,2 bp,2 / 2     (5.8)

    23

    in which the stiffener width bs is as shown in Figure 5.4.

  5. The critical buckling stress σcr,s for an intermediate stiffener should be obtained from:

    Image

    where:

    k is the spring stiffness per unit length, see 5.5.3.1(2);
    Is is the effective second moment of area of the stiffener, using the thickness t and notional effective width 12t of adjacent plane cross-section parts about the centroidal axis a - a of its effective cross-section, see Figure 5.6(a).
  6. The reduction factor χd for the distortional buckling resistance of an intermediate stiffener should be obtained from the value of σcr,s using the method given in 5.5.3.1(5).
  7. If χd < 1 it may optionally be refined iteratively, starting the iteration with modified values of ρ obtained using 5.5.2(4) with σcom,Ed equal to χd fo/γM1, so that:

    Image

  8. If iteration is carried out, it should be continued until the current value of χd is approximately equal to, but not more than, the previous value.
  9. The reduced effective area of the stiffener As,red allowing for distortional buckling should be taken as:

    Image

    where σcom,Ed is compression stress at the centreline of the stiffener calculated on the basis of the effective cross-section.

  10. In determining effective section properties, the reduced effective area As,red should be represented by using a reduced thickness tred = χd teff for all the cross-section parts included As

5.5.4 Trapezoidal sheeting profiles with intermediate stiffeners

5.5.4.1 General
  1. This sub-clause should be used in association with 5.5.3.3 for flanges with intermediate flange stiffeners and for webs with intermediate stiffeners.
  2. Interaction between distortional buckling of intermediate flange stiffeners and intermediate web stiffeners should also be taken into account using the method given in 5.5.4.4.
5.5.4.2 Flanges with intermediate stiffeners
  1. If it is subject to uniform compression, the effective cross-section of a flange with intermediate stiffeners should be assumed to consist of the reduced effective areas As,red of up to two intermediate stiffeners and two strips of width 0,5bp and thickness teff adjacent to the edges supported by webs, see Figure 5.5f). 24
  2. For one central flange stiffener, the elastic critical buckling stress σcr,s should be obtained from:

    Image

    where:

    bp is the notional flat width of plane cross-section part shown in Figure 5.6;
    bs is the stiffener width, measured around the perimeter of the stiffener, see Figure 5.6(c);
    kw is a coefficient that allows for partial rotational restraint of the stiffened flange by the webs, see (5) and (6);
    and As and Is are as defined in 5.5.3.3 and Figure 5.6.

    Figure 5.6 – Effective cross section for calculation of Is and As for compression flange with two or one stiffener

    Figure 5.6 – Effective cross section for calculation of Is and As for compression flange with two or one stiffener

  3. For two symmetrically placed flange stiffeners, the elastic critical buckling stress σcr,s should be obtained from:

    Image

    with:

    be = 2bp,1 + bp,2 + 2bs

    b1 = bp,1 + 0,5 br

    where:

    bp,1 is the notional flat width of an outer plane cross-section part, as shown in Figure 5.6;
    bp,2 is the notional flat width of the central plane cross-section part, as shown in Figure 5.6;
    bs is the stiffener width, measured around the perimeter of the stiffener, see Figure 5.6(c).
  4. If there are three stiffeners, the one in the middle should be assumed to be ineffective.
  5. The value of kw may be calculated from the compression flange buckling wavelength lb as follows:

    where:

    sw is the slant height of the web, see Figure 5.7(a). 25
    lb half wavelength for elastic buckling of stiffener, see (7).
  6. Alternatively, the rotational restraint coefficient κw may conservatively be taken as equal to 1,0 corresponding to a pin-jointed condition.
  7. The values of lb and κwo may be determined from the following:
  8. The reduced effective area of the stiffener As,red allowing for distortional buckling (flexural buckling of an intermediate stiffener) should be taken as:

    Image

  9. If the webs are unstiffened, the reduction factor χd should be obtained directly from σcr,s using the method given in 5.5.3.1(5).
  10. If the webs are also stiffened, the reduction factor χd should be obtained using the method given in 5.5.3.1(5), but with the modified elastic critical stress σcr,mod given in 5.5.4.4.
  11. In determining effective section properties, the reduced effective area As,red should be represented by using a reduced thickness tred = χd teff for all the cross-section parts included in As.
5.5.4.3 Webs with up to two intermediate stiffeners under stress gradient
  1. The effective cross-section of the compressed zone of a web should be assumed to consist of the reduced effective areas, As,red of up to two intermediate stiffeners, a strip adjacent to the compression flange and a strip adjacent to the centroidal axis of the profile cross-section, see Figure 5.7. Webs under uniform compression stress should be treated analogously to stiffened flanges.
  2. The effective cross-section of a web as shown in Figure 5.7 should be taken to include:
    1. a strip of width sa/2 and effective thickness teff,a adjacent to the compression flange;
    2. the reduced effective area As,red of each web stiffener up to a maximum of two;
    3. a strip of width 2sn/3 adjacent to the effective centroidal axis; 26
    4. the part of the web in tension.

      Figure 5.7 - Effective cross-sections of webs of cold-formed profiled sheets

      Figure 5.7 - Effective cross-sections of webs of cold-formed profiled sheets

  3. The initial effective areas should be obtained from the following:

    in which the dimensions sa, ssa, sb, ssb, and sn are as shown in Figure 5.7 and teff,a, teff,b and teff,n are given in (5).

  4. Initially the location of the effective centroidal axis should be based on the effective area of the flanges but with the gross area of the webs.
  5. If the slenderness Image of the part of the web which is in compression is larger than Image (see 5.5.2(4)), the effective thickness tteff,a, tteff,b and tteff,n should be determined as follows:

    teff = ρ t     (5.22)

    27

    where ρ is calculated using expression (5.2) with slenderness Image and stress relation factor ψ according to Table 5.5, where ec and et are the distances from the effective centroidal axis to the system line of the compression and tension flange, see Figure 5.7, and the dimensions ha, hb, hsa, hsb, sn and ϕ are as shown in Figure 5.7.

  6. To calculate the initial effective area Asa and Asb of web stiffeners, sa and sb are divided into two equal parts sa/2 and sb/2. The web part sn over the centroidal axis is divided into one part sn/3 adjacent to the stiffener, Figure 5.7 (dl) and (d3), and one part 2sn/3 adjacent to the centroidal axis.
    Image Table 5.5 - Slenderness Image and stress relation factor ψ for a web with stiffeners
    Web part location Web part Slenderness Image Stress relation factor ψ
    No stiffeners, Figure 5.7 (a)
    Between compression flange and centroidal axis sn Image Image
    One stiffeners, Figure 5.7 (b)
    Adjecent to compression flange sa Image Image
    Adjacent to centroidal axis sn Image Image
    Two stiffeners, Figure 5.7 (c)
    Adjacent to compression flange sa Image Image
    Between stiffeners sb Image Image
    Adjacent to centroidal axis sn Image Image

    Image

  7. For a single stiffener, or for the stiffener closer to the compression flange in webs with two stiffeners, the elastic buckling stress scr,sa should be determined using:

    Image

    in which s1 and s2 are given by the following:

    where:

    κf is a coefficient that allows for partial rotation restraint of the stiffened web by the flanges; 28
    Isa is the second moment of area of a stiffener cross-section comprising the fold, width ssa, and two adjacent strips, each of width 12t, about its own centroidal axis parallel to the plane web cross-section parts, see Figure 5.7(e). In calculating Isa the possible difference in slope between the plane cross-section parts on either side of the stiffener may be neglected.
  8. In the absence of a more detailed investigation, the rotational restraint coefficient κf may conservatively be taken as equal to 1,0 corresponding to a pin-jointed condition.
  9. For a single stiffener in compression, or for the stiffener closer to the compression flange in a web with two stiffeners, the reduced effective area Asa,red (Step 2 in Figure 5.5) should be determined from:

    Image

  10. If the flanges are also stiffened, the reduction factor χd should be obtained using the method given in 5.5.3.1(5), but with the modified elastic critical stress σcr,mod given in 5.5.4.4.
  11. For a single stiffener in tension, the reduced effective area Asa,red should be taken as equal to Asa.
  12. For webs with two stiffeners, the reduced effective area Asb,red the second stiffener, close to the neutral axis, should be taken as equal to Asb
  13. In determining effective section properties, the reduced effective area Asa,red should be represented by using a reduced thickness tred = χd teff for all the cross-section parts included in Asa.
  14. If χd < 1 it may optionally be refined iteratively, see 5.5.3(7).
  15. For the effective section properties at serviceability limit states, see 7.1.
5.5.4.4 Sheeting with flange stiffeners and web stiffeners
  1. (1) In the case of sheeting with intermediate stiffeners in the flanges and in the webs, see Figure 5.8, interaction between the distortional buckling of the flange stiffeners and the web stiffeners should be allowed for by using a modified elastic critical stress σCr,mod for both types of stiffeners, obtained from:

    Image

    where:

    σcr,s is the elastic critical stress for an intermediate flange stiffener, see 5.5.4.2(2) for a flange with a single stiffener or 5.5.4.2(3) for a flange with two stiffeners;
    σcr,sa is the elastic critical stress for a single web stiffener, or the stiffener closer to the compression flange in webs with two stiffeners, see 5.5.4.3(7).
    βs = 1 – (ha + 0,5hsa) / ec for a profile in bending
    βs = 1 for a profile in axial compression
29

Figure 5.8 – Effective cross section of cold-formed profiled sheeting with flange stiffeners and web stiffeners

Figure 5.8 – Effective cross section of cold-formed profiled sheeting with flange stiffeners and web stiffeners

30

6 Ultimate limit states

6.1 Resistance of cross-sections

6.1.1 General

  1. The rules in this section apply to the design by calculation.
  2. Design assisted by testing may be used instead of design by calculation for any resistance, see Section 9 and Annex A.

    NOTE Design assisted by testing is particularly likely to be beneficial for cross sections with relatively high bp/t ratios, e.g. in relation to inelastic behaviour, web crippling or shear lag.

  3. For design by calculation, the effects of local buckling and distortional buckling should be taken into account by using effective section properties determined as specified in 5.5.
  4. The buckling resistance of sheeting members in compression should be verified as specified in 6.2.

6.1.2 Axial tension

  1. The design resistance of a cross-section for uniform tension Nt,Rd should be determined from:

    Image

    where:

    Ag is the gross area of the cross-section;
    Fnet,Rd is the net-section resistance for the appropriate type of mechanical fastener.

6.1.3 Axial compression

  1. The design resistance of a cross-section for compression Nc,Rd should be determined from:
  2. The internal normal force in a member should be taken as acting at the centroid of its gross cross-section. This is a conservative assumption, but can be used without further analysis. Further analysis may give a more realistic situation of the internal forces for instance in case of uniformly building-up of normal force in the compression cross-section part.
  3. The design compression resistance of a cross-section for uniform compression should be assumed to act at the centroid of its effective cross-section. If this does not coincide with the centroid of its gross cross-section, the shift eN of the centroidal axes (see Figure 6.1) should be taken into account, using the method given in 31 6.1.9. If the shift of the neutral axis gives a favourable result, then that shift should be neglected only if the shift has been calculated at yield strength and not with the actual compressive stresses.

    Figure 6.1 – Illustration of shift of neutral axis in cross-section under compression

    Figure 6.1 – Illustration of shift of neutral axis in cross-section under compression

6.1.4 Bending moment

6.1.4.1 Elastic and elastic-plastic resistance with yielding at the compressed flange
  1. The design moment resistance of a cross-section for bending Mc,Rd should be determined as follows:

    where:

    λ is the slenderness of the cross-section part which correspond to the largest value of λ / λel ;

    For double supported plane cross-section parts Image and Image where Image is found in Table 5.2; For stiffened cross-section parts Image and λel = 0,25, see 5.5.3.1.

    NOTE The resulting bending moment resistance as a function of the slenderness of the most slender cross-section part is illustrated in Figure 6.2.

    Figure 6.2 - Bending moment resistance as a function of the slenderness

    Figure 6.2 - Bending moment resistance as a function of the slenderness

  2. Expression (6.5) is applicable provided that the slope ϕ of the web relative to the flanges (see Figure 6.5) is less than 60°.
  3. If (2) is not fulfilled the following expression should be used: 32

    Mc,Rd = Wel fo / γM1     (6.6)

  4. The effective section modulus Weff should be based on an effective cross-section that is subject only to bending moment, with a maximum stress σmax,Ed equal to fo / γM1, allowing for the effects of local and distortional buckling as specified in 5.5. Where shear lag is relevant (see EN 1999-1-1), allowance should also be made for its effects.
  5. The stress ratio ψ = σ2 / σ1 used to determine the effective portions of the web may be obtained by using the effective area of the compression flange but the gross area of the web, see Figure 6.3.
  6. If yielding occurs first at the compression edge of the cross-section, unless the conditions given in 6.1.4.2 are met the value of Weff should be based on a linear distribution of stress across the cross-section.

    Figure 6.3 - Effective cross-section for resistance to bending moments

    Figure 6.3 - Effective cross-section for resistance to bending moments

  7. If redistribution of bending moments is assumed in the global analysis the provisions given in 7.2 should be satisfied. If the residual moment at the intermediate support is not assumed to be zero, the acting residual moment should be determined by test.
6.1.4.2 Elastic and elastic-plastic resistance with yielding at the tension flange only
  1. Provided that yielding occurs first at the tension edge, plastic reserves in the tension zone may be utilised without any strain limitation until the maximum compressive stress σcom,Ed reaches fo/γM1. In this clause only the bending case is considered. For axial load and bending 6.1.8 or 6.1.9 should be applied.
  2. In this case, the effective partially plastic section modulus Wpp,eff should be based on a stress distribution that is bilinear in the tension zone but linear in the compression zone.
  3. In the absence of a more detailed analysis, the effective thickness teff of the webs may be obtained using 5.5.2 by basing ec on the bilinear stress distribution (see Figure 6.4), by assuming ψ = – 1.

    Figure 6.4 - Measure ec for determination of effective thickness

    Figure 6.4 - Measure ec for determination of effective thickness

  4. If redistribution of bending moments is assumed in the global analysis the provisions given in 7.2 should be satisfied. If the residual moment at the intermediate support is not assumed to be zero, the acting residual moment should be determined by test.
6.1.4.3 Effects of shear lag
  1. The effects of shear lag should be taken into account according to EN 1999-1-1. 33
  2. Shear lag effects may be ignored for flanges with b/t ≤ 300.

6.1.5 Shear force

  1. The shear resistance Vb,Rd should be determined from:

    Vb,Rd = (hw / sin ϕ) t fbv / γM1     (6.7)

    where:

    fbv is the shear strength considering buckling according to Table 6.1;
    hw is the web height between the midlines of the flanges, see Figure 6.5;
    ϕ is the slope of the web relative to the flanges.
    Table 6.1 - Shear buckling strength fbv in relation to web slenderness parameter Image
    Web slenderness parameter Web without stiffening at the support Web with stiffening at the support 1)
    Image 0,58 fo 0,58 fo
    Image Image Image
    Image Image Image
    1) Stiffening at the support, such as cleats, arranged to prevent distortion of the web and designed to resist the support reaction.
  2. The web slenderness parameter Image should be obtained from the following:

    with:

    Image

    where:

    Is is the second moment of area of the individual longitudinal stiffener, about the axis a - a as indicated in Figure 6.5;
    sd is the total developed slant height of the web, as indicated in Figure 6.5;
    sp is the slant height of the largest plane part in the web, see Figure 6.5;
    sw is the slant height of the web, as shown in Figure 6.5, between the midpoints of the comers, see Figure 6.5.
    34

    Figure 6.5 - Geometry of a longitudinally stiffened web and effective cross section of stiffener

    Figure 6.5 - Geometry of a longitudinally stiffened web and effective cross section of stiffener

6.1.6 Torsion

  1. Torsion stiffness and resistance is negligible in profiled sheeting.

6.1.7 Local transverse forces

6.1.7.1 General
  1. To avoid crushing, crippling or buckling in a web subject to a support reaction or other local transverse force applied through the flange, the transverse force FEd should satisfy:

    FEdRw,Rd     (6.10)

    where Rw,Rd is the local transverse resistance of the web.

  2. The local transverse resistance of a web Rw,Rd should be obtained as follows:
    1. for unstiffened webs: from 6.1.7.2
    2. for stiffened webs: from 6.1.7.3
  3. Where the local load or support reaction is applied through a cleat that is arranged to prevent distortion of the web and is designed to resist the local transverse force, the local resistance of the web to the transverse force need not be considered.
6.1.7.2 Cross-sections with unstiffened webs
  1. The local transverse resistance of an unstiffened web, see Figure 6.6, should be determined as specified in (2), provided that both of the following conditions are satisfied: 35

    where:

    hw is the web height between the midlines of the flanges;
    r is the internal radius of the corners;
    ϕ is the slope of the web relative to the flanges [degrees].

    Figure 6.6 - Examples of cross-section with two or more webs

    Figure 6.6 - Examples of cross-section with two or more webs

  2. Where both conditions specified in (1) are satisfied, the local transverse resistance Rw,Rd per web of the sheeting profile should be determined from:

    Image

    where:

    la is the effective bearing length for the relevant category, see (4);
    α is the coefficient for the relevant category, see (3);
    sw is the slant length of the web (= hw / sinϕ);
    r is the inner bending radius (r < 10 t).
  3. The value of the coefficient α should be obtained from Figure 6.7.
  4. The values of la should be obtained from (5). The maximum design value for la is 200 mm. When the support is a cold-formed section with one web or round tube, for sS should be taken a value of 10 mm. The relevant category (1 or 2) should be based on the clear distance e between the local load and the nearest support, or the clear distance c from the support reaction or local load to a free end, see Figure 6.7.
  5. The value of the effective bearing length la for sheeting profiles should be obtained from the following:
    1. for Category 1:

      la = ss but la ≤ 40 mm     (6.13a)

    2. for Category 2:

      if βv ≤ 0,2:     la = ss     (6.13b)

      if βv ≥ 0,3:     la = 10mm     (6.13c)

      if 0,2 < βv < 0,3: interpolate linearly between the values of la for 0,2 and 0,3 with:

      Image

      in which |VEd,l| and |VEd,2| are the absolute values of the transverse shear force on each side of the local load or support reaction, and |VEd,l| ≥ |VEd,2| and ss is the actual length of stiff bearing.

    36

    Figure 6.7 - Local loads and support-categories for cross-sections with two or more webs

    Figure 6.7 - Local loads and support-categories for cross-sections with two or more webs

37
6.1.7.3 Stiffened webs
  1. The local transverse resistance of a stiffened web may be determined as specified in (2) for cross-sections with longitudinal web stiffeners folded in such a way that the two folds in the web are on opposite sides of the system line of the web joining the points of intersection of the midline of the web with the midlines of the flanges, see Figure 6.8, that satisfy the condition:

    2 < emax/ t < 12     (6.15)

    where:

    emax is the larger eccentricity of the folds relative to the system line of the web.

  2. For cross-sections with stiffened webs satisfying the conditions specified in (1), the local transverse resistance of a stiffened web may be determined by multiplying the corresponding value for a similar unstiffened web, obtained from 6.1.7.2, by the factor κa,s given by:

    κa,s = 1,45 – 0,05 emax/ t    but    κa,s ≤ 0,95 + 35 000 t2 emin/(bd2 sp)     (6.16)

    where:

    bd is the developed width of the loaded flange, see Figure 6.8;
    emin is the smaller eccentricity of the folds relative to the system line of the web, see Figure 6.8;
    sp is the slant height of the plane web cross-section part nearest to the loaded flange, see Figure 6.8.

    Figure 6.8 - Support loads and geometry of stiffened webs

    Figure 6.8 - Support loads and geometry of stiffened webs

6.1.8 Combined tension and bending

  1. Cross-sections subject to combined axial tension NEd and bending moment My,Ed should satisfy the criterion:

    Image

    38

    where:

    Nt,Rd is the design resistance of a cross-section for uniform tension (6.1.2);
    Mcy,Rd,ten is the design moment resistance of a cross-section for maximum tensile stress if subject only to moment about the y - y axes (6.14).
  2. If Mcy,Rd,comMcy,Rd,ten, where Mcy,Rd,com is the moment resistance for the maximum compressive stress in a cross-section that is subject to moment only, the following criterion should also be satisfied:

    Image

6.1.9 Combined compression and bending

  1. Cross-sections subject to combined axial compression NEd and bending moment My,Ed should satisfy the criterion:

    Image

    in which Nc,Rd is as defined in 6.1.3 and Mcy,Rd,com is as defined in 6.1.8.

  2. The additional moment ΔMy,Ed due to shift of the centroidal axis should be taken as:

    ΔMy,Ed = NEd eN     (6.18b)

    in which eN is the shift of the y - y centroidal axes due to axial forces, see 6.1.3(3).

  3. If Mcy,Rd,tenMcy,Rd,com the following criterion should also be satisfied:

    Image

    in which Mcy,Rd,ten is as defined in 6.1.8.

6.1.10 Combined shear force, axial force and bending moment

  1. Provided that VEd/Vw,Rd (see below) does not exceed 0,5, the design resistance to bending moment and axial force need not be reduced to allow for the shear force. If VEd/Vw,Rd is more than 0,5 the combined effects of an axial force NEd, a bending moment MEd and a shear force VEd should satisfy:

    Image

    where:

    NRd is the design resistance of the cross-section for tension or compression given in 6.1.2 or 6.1.3;
    My,Rd is the design moment resistance of the cross-section given in 6.1.4; 39
    Vw,Rd is the design shear resistance of the web given in 6.1.5. For members with more than one web Vw,Rd is the sum of the resistances of the webs;
    Mf,Rd is the design plastic moment resistance of the cross-section consisting of the effective area of the flanges only;
    Mpl,Rd is the design plastic moment resistance of the cross-section consisting of the effective area of the flanges and the fully effective web irrespective of its section class.

6.1.11 Combined bending moment and local load or support reaction

  1. Cross-sections subject to the combined action of a bending moment MEd and a transverse force due to a local load or support reaction FEd should satisfy the following:

    Image

    Image

    Image

    where:

    Mc,Rd is the moment resistance of the cross-section given in 6.1.4.1;
    Rw,Rd is the appropriate value of the sum of the local transverse resistances of the individual webs from 6.1.7.
  2. In expression (6.22) the bending moment MEd may be calculated at the edge of the support.

6.2 Buckling resistance

6.2.1 General

  1. The effects of local and distortional buckling should be taken into account. Methods as specified in 5.5 may be used.
  2. The internal axial force in a sheeting should be taken as acting at the centroid of its gross cross-section.
  3. The resistance of sheeting to axial compression should be assumed to act at the centroid of its effective cross-section. If this does not coincide with the centroid of its gross cross-section, moments corresponding to the shift of the centroidal axes (see Figure 6.9) should be taken into account, using the method given in 6.2.3.

    Figure 6.9 – Illustration of shift of centroidal axis of effective cross-section

    Figure 6.9 – Illustration of shift of centroidal axis of effective cross-section

    40

6.2.2 Axial compression

6.2.2.1 Design flexural buckling resistance
  1. The design buckling resistance for axial compression Nb,Rd should be obtained from:

    Nb,Rd = χAefffo / γM1     (6.23)

    where:

    Aeff is the effective area of the cross-section, obtained from Section 5 by assuming a uniform compressive stress σcom,Ed equal to fo/γM1;
    χ is the appropriate value of the reduction factor for bucklilng resistance.
  2. The reduction factor χ for buckling resistance should be determined from:

    Image

    with:

    Image

    where:

    α is an imperfection factor;
    Image is the limit of the horizontal plateau;
    λ is the slenderness parameter for the relevant buckling mode.
  3. The imperfection factor for sheeting is α = 0,13 and the limit of the horizontal plateau is Image.
  4. The slenderness parameter for flexural buckling should be determined from the following:

    Image

    where:

    l is the buckling length for flexural buckling about the y – y axes (ly);
    i is the radius of gyration about the corresponding axes (iy), based on the properties of the gross cross-section.

6.2.3 Bending and axial compression

  1. All members subject to combined bending and axial compression should satisfy the criterion:

    Image

    where:

    Aeff is the effective area of an effective cross-section that is subject only to axial compression; see Figure 6.10(a);
    Weff,y,com is the effective section modulus for the maximum compressive stress in an effective cross-section that is subject only to moment about the y - y axis, see Figure 6.10 (b); 41
    ΔMy,Ed is the additional moment due to possible shift of the centroidal axis in the y direction, see 6.1.9(2);
    χy is the reduction factor from 6.2.2 for buckling about the y - y axis;
    ωx is an interaction expression, see (2).

    Figure 6.10 – Models for calculation of effective section properties

    Figure 6.10 – Models for calculation of effective section properties

  2. For sheeting subjected to combined axial force and unequal end moments and/or transverse loads, different sections along the span should be checked. The actual bending moment in the studied section is used in the interaction expression and

    Image

    where:

    xs is the distance from the studied section to a hinged support or a point of contra-flexure of the deflection curve for elastic buckling of an axial force only, see Figure 5.9 of EN1999-1-1.
    lc = KL is the buckling length, see Table 5.7 of EN1999-1-1.

    NOTE For simplification ωx = 1 may be used.

6.3 Stressed skin design

6.3.1 General

  1. The interaction between structural members and sheeting panels that are designed to act together as parts of a combined structural system, may be allowed for as described in this chapter 6.3
  2. Diaphragms may be formed from profiled sheeting of aluminium used as roof or wall cladding.

    NOTE Information on the verification of such diaphragms can be obtained from:

    ECCS Publication No. 88 (1995): European recommendations for the application of metal sheeting acting as a diaphragm.

6.3.2 Diaphragm action

  1. In stressed skin design, advantage may be taken of the contribution that diaphragms of sheeting used as roofing, flooring or wall cladding make to the overall stiffness and strength of the structural frame, by means of their stiffness and strength in shear.
  2. Roofs and floors may be treated as deep plate girders extending throughout the length of a building, resisting transverse in-plane loads and transmitting them to end gables, or to intermediate stiffened frames. The panel of sheeting may be treated as a web that resists in-plane transverse loads in shear, with the edge members acting as flanges that resist axial tension and compression forces, see Figures 6.11 and 6.12. 42
  3. Similarly, rectangular wall panels may be treated as bracing systems that act as shear diaphragms to resist in-plane forces.

    Figure 6.11 - Stressed skin action in a flat-roof building

    Figure 6.11 - Stressed skin action in a flat-roof building

6.3.3 Necessary conditions

  1. Methods of stressed skin design that utilize sheeting as an integral part of a structure, may be used only under the following conditions:
  2. Stressed skin design should be used predominantly in low-rise buildings, or in the floors and facades of high-rise buildings.
  3. Stressed skin diaphragms should be used predominantly to resist wind loads, snow loads and other loads that are applied through the sheeting itself. They may also be used to resist small transient loads, such as surge from light overhead cranes or hoists on runway beams, but may not be used to resist permanent external loads, such as those from plant. 43

    Figure 6.12 - Stressed skin action in a pitched roof building

    Figure 6.12 - Stressed skin action in a pitched roof building

6.3.4 Profiled aluminium sheet diaphragms

  1. In a profiled aluminium sheet diaphragm, see Figure 6.13, both ends of the sheets should be attached to the supporting members by means of self-tapping screws, self-drilling screws, welding, bolts or other fasteners of a type that will not work loose in service, pull out, or fail in shear before causing tearing of the sheeting. All such fasteners should be fixed directly through the sheeting into the supporting member, for example through the troughs of profiled sheets, unless special measures are taken to ensure that the joints effectively transmit the forces assumed in the design.
  2. The seams between adjacent sheets should be fastened by rivets, self-drilling screws, welds, or other fasteners of a type that will not work loose in service, pull out, or fail in shear before causing tearing of the sheeting. The spacing of such fasteners should not exceed 500 mm.
  3. The distances from all fasteners to the edges and ends of the sheets should be adequate to prevent premature tearing of the sheets.
  4. Small randomly arranged openings, up to 3% of the relevant area, may be introduced without special calculation, provided that the total number of fasteners is not reduced. Openings up to 15% of the relevant area may be introduced if justified by detailed calculations. Areas that contain larger openings should be split into smaller areas, each with full diaphragm action.
  5. All sheeting that also forms part of a stressed-skin diaphragm should first be designed for its primary purpose in bending. To ensure that any deterioration of the sheeting would be apparent in bending before the resistance to stressed skin action is affected, it should then be verified that the shear stress due to diaphragm action does not exceed 0,25fo/γM1
  6. The shear resistance of a stressed-skin diaphragm should be based on the least tearing strength of the seam fasteners or the sheet-to-member fasteners parallel to the corrugations or, for diaphragms fastened only to longitudinal edge members, the end sheet-to-member fasteners. The calculated shear resistance for any other type of failure should exceed this minimum value by at least the following:

    Figure 6.13 - Arrangement of an individual panel

    Figure 6.13 - Arrangement of an individual panel

6.4 Perforated sheeting with the holes arranged in the shape of equilateral triangles

  1. Perforated sheeting may be designed by calculation, provided that the rules for non-perforated sheeting are modified by introducing the effective thicknesses given below.

    NOTE These calculation rules tend to give conservative values. More economical solutions might be obtained from design assisted by testing.

  2. Provided that 0,2 ≤ d/a ≤ 0,9 gross section properties may be calculated using 6.1.2 to 6.1.5, but replacing t by ta,eff obtained from:

    ta,eff = 1,18t(1 – d/(0,9a))     (6.28)

    where:

    d is the diameter of the perforations;
    a is the spacing between the centres of the perforations.
  3. Provided that 0,2 ≤ d/a ≤ 0,9 effective section properties may be calculated using 5.5, but replacing t by tb,eff obtained from:

    Image

  4. Provided that 0,2 ≤ d/a ≤ 0,8 the resistance of a single unstiffened web to local transverse forces may be calculated using 6.1.7, but replacing t by tc,eff obtained from:

    Image

    where:

    sper is the slant height of the perforated portion of the web, centric in the web height;
    sw is the total slant height of the web.
45

7 Serviceability limit states

7.1 General

  1. The rules for serviceability limit states given in EN 1999-1-1 should also be applied to cold-formed sheeting.
  2. The properties of the effective cross-section for serviceability limit states obtained from (3) should be used in all serviceability limit state calculations for cold-formed sheeting.
  3. The second moment of area may be calculated by interpolation of gross cross-section and effective cross-section using the expression:

    Ieff,ser = Igr - σgr(Igr - Ieff) / fo     (7.1)

    where:

    Igr is the second moment of area of gross section;
    Ieff is the second moment of area of the effective cross-section in the ultimate limit state, with allowance for local buckling;
    σgr is the maximum compressive bending stress in the serviceability limit state, based on the gross cross-section (positive in the formula).
  4. The effective second moment of area Ieff,ser may be taken as variable along the span. Alternatively a uniform value may be used, based on the maximum span moment due to serviceability loading.

7.2 Plastic deformation

  1. In case of plastic global analysis, the combination of support moment and support reaction at an internal support should not exceed 0,9 times the combined design resistance determined using γM,ser and Ieff,ser according to 7.1(3).
  2. The combined design resistance may be determined from expression (6.22) in 6.1.11, but using the effective cross-section for serviceability limit states and γM,ser .

7.3 Deflections

  1. The deflections may be calculated assuming elastic behaviour.
  2. The influence of slip in the joints (for example in the case of continuous sheeting with overlaps) should be considered in the calculation of deflections, forces and moments.

    NOTE For commonly used fasteners according to 8.2 and 8.3 the slip may be ignored.

  3. With reference to EN 1990 – Annex A1.4 limits for deflections should be specified for each project and agreed with the client.

    NOTE The National Annex may specify the limits.

46

8 Joints with mechanical fasteners

8.1 General

  1. Joints with mechanical fasteners should be compact in shape. The positions of the fasteners should be arranged to provide sufficient room for satisfactory assembly and maintenance.
  2. The shear forces on individual mechanical fasteners in a joints may be assumed to be equal, provided that:
  3. For design by calculation, the resistance of mechanical fasteners subject to predominantly static loads should be determined from 8.2 for blind rivets and 8.3 for self-tapping screws and self-drilling screws.
  4. The meanings of the symbols, used in the above named clauses are found in EN 1999-1-1 with additions in 1.4 of EN 1999-1-4.
  5. The partial factor for calculating the design resistances of mechanical fasteners should be taken as γM3 according to 2(3).

    Figure 8.1 - End distance, edge distance and spacing for fasteners

    Figure 8.1 - End distance, edge distance and spacing for fasteners

  6. The pull-through resistances given in 8.2.3.1 for blind rivets or in 8.3.3.1 for self-tapping screws and self-drilling screws are depending on the location of the fasteners and should be reduced if the fasteners are not located centrally in the troughs of the sheeting. If attachment is at a quarter point, the design resistance should be reduced to 0,9Fp,Rd and if there are fasteners at both quarter points, the resistance should be taken as 0,7Fp,Rd per fastener, see Table 8.3.
  7. For a fastener loaded in combined shear and tension, provided that Fp,Rd, Fo,Rd, Fb,Rd and Fn,Rd are determined by calculation on the basis of 8.2 for blind rivets or 8.3 for self-tapping screws and self-drilling screws, the resistance of the fastener to combined shear and tension may be verified using:

    Image

  8. The gross section distortion may be neglected if the design resistance is obtained from 8.2.3 and 8.3.3 provided that the fastening is through a flange not more than 150 mm wide.
  9. The diameter of holes for screws should be in accordance with the manufacturer’s guidelines. These guidelines should be based on following criteria: 47
  10. The design rules for blind rivets are valid only if the diameter of the hole is not more than 0,1 mm larger than the diameter if the rivet.

8.2 Blind rivets

8.2.1 General

  1. The resistance of blind rivets loaded in shear is the minor value of the bearing resistance Fb,Rd, the net-section resistance Fnet,Rd of the sheeting and the shear resistance of the fastener Fv,Rd.
  2. The shank of the blind rivet should be of EN AW- 5019.
  3. Blind rivets according to EN ISO 15973, EN ISO 15974, EN ISO 15977, EN ISO 15978, EN ISO 15981 or EN ISO 15982 should be used

8.2.2 Design resistances of riveted joints loaded in shear

8.2.2.1 Bearing resistance

Image

Fb,Rd = 1,5 fu,min t d / γM3     for tsup / t ≥ 2,5     (8.2b)

For thicknesses 1,0 < tsup / t < 2,5 the bearing resistance Fb,Rd may be obtained by linear interpolation.

8.2.2.2 Net section resistance

Fnet,Rd = Anet fu / γM3     (8.3)

8.2.2.3 Shear resistance

Fv,Rd = 38 d2 / γM3 [N] with d in mm     (8.4)

Conditions for bearing and shear resistance:

8.2.3 Design resistances for riveted joints loaded in tension

8.2.3.1 Pull-through resistance

Fp,Rd = 2,35 αE t fo / γM3 [N] with t in mm and fo in N/mm2 ; αE according to Table 8.3     (8.5)

Conditions:

8.2.3.2 Pull-out resistance

Conditions:

8.2.3.3 Tension resistance

Ft,Rd = 47 d2 /γM3 [N], where d to be taken in mm.     (8.8)

8.3 Self-tapping / self-drilling screws

8.3.1 General

  1. The resistance of screws loaded in shear is the minor value of the bearing resistance Fb,Rd, the net-section resistance Fnet,Rd of the sheeting and the shear resistance of the fastener Fv,Rd.
  2. The limits for diameters of screws given in the following clauses should be valid, unless other limits can be obtained and verified by adequate tests.
  3. The limits for strength values of supporting materials should be valid, unless other limits can be obtained and verified by adequate tests.
  4. Self-tapping screws according to EN ISO 1479, EN ISO 1481 or ISO 7049 should be used.
  5. Self-drilling screws according to EN ISO 15480 or EN ISO 15481 should be used.

8.3.2 Design resistance of screwed joints loaded in shear

8.3.2.1 Bearing resistance
  1. Bearing resistance if supporting members are of steel or aluminium is given by:

    Image

    Fb,Rd = 1,5 fu,min t d / γM3     for tsup / t ≥ 2,5     (8.9b)

    For thicknesses 1,0 < tsup / t < 2,5 the bearing resistance Fb,Rd may be obtained by linear interpolation.

    Conditions:

  2. Bearing resistance of aluminium sheeting if supporting members are of timber is given by:

    Fb,Rd ≤ l,5 t d fu,min / γM3 [N]     (8.10)

  3. For resistance of supporting member of timber, see EN 1995-1-1, Section 8, steel-to-timber connection.

    Conditions:

49
8.3.2.2 Net section resistance

Fnet,Rd = Anet fu / γM3     (8.11)

8.3.2.3 Shear resistance

Design shear resistance of screws of steel or stainless steel is given by:

Fv,Rd = 380 As / γM3 [N], with As in mm2     (8.12)

8.3.3 Design resistance of screwed joints loaded in tension

8.3.3.1 Pull-through resistance
  1. The pull-through resistance of screwed joints loaded in tension is given by:

    Image

    with: t and dw in mm and fu in N/ mm2 and

    Conditions:

    Table 8.1 - Correction factor αL, to take account of tensile bending stresses at support fastenings
    Ultimate strength [N/mm2] αL
    Span L < 1,5 m Span l,5 ≤ L ≤ 4,5 m Span L > 4,5 m
    < 215 1 1 1
    ≥ 215 1 1,25- L/6 0,5

    NOTE At end supports without bending stresses and at connections at the upper flange always αL = 1

    Table 8.2 - Correction factor αM to take account of the material of the washer
    Material of the washer αM
    Carbon steel, stainless steel 1,0
    Aluminium 0,8
    50
    Table 8.3 - Correction factor αE to take account of the location of the fasteners
    For the flange in contact with the support without contact
    Joint Image Image Image Image Image Image Image
    αE 1,0 bu ≤ 150:0,9
    bu ≤ 150:0,7
    0,7 0,9 0,7  0,7 1,0 0,9

    NOTE The combination of correction factors is not necessary. The smallest value applies.

8.3.3.2 Pull-out resistance
  1. The pull-out resistance for self- tapping screws and self-drilling screws of steel or stainless steel, where supporting members are of steel or aluminium, is given by:

    Image

    Conditions:

  2. For supporting members of timber, see EN 1995-1-1, Section 8.
8.3.3.3 Tension resistance
  1. The design tension resistance of screws of steel or stainless steel is given by:

    Ft,Rd = 560 As / γM3 [N] with AS in mm2     (8.15)

51

9 Design assisted by testing

  1. This Section 9 may be used to apply the principles for design assisted by testing given in EN 1990 with the additional specific requirements of cold-formed sheeting.
  2. Testing of profile sheeting should apply the principles given in Annex A.
  3. Tensile testing of aluminium alloys should be carried out in accordance with EN 10002-1. Testing of other aluminium properties should be carried out in accordance with the relevant European Standards.
  4. Testing of fasteners and connections should be carried out in accordance with the relevant European Standard or International Standard.

    NOTE Pending availability of an appropriate European or International Standard, information on testing procedures for fasteners can be obtained from:

    ECCS Publication No. 21 (1983): European recommendations for steel construction: the design and testing of connections in steel sheeting and sections;

    ECCS Publication No. 42 (1983): European recommendations for steel construction: mechanical fasteners for use in steel sheeting and sections.

52

Annex A – Testing procedures

[normative]

A.1 General

  1. This Annex A gives appropriate standardized testing and evaluation procedures for a number of tests that are commonly required in practice, as a basis for harmonization of future testing.

    NOTE 1 In the field of cold-formed sheeting, many standard products are commonly used for which design by calculation might not lead to economical solutions, so it is frequently desirable to use design assisted by testing.

    NOTE 2 Image The National Annex may give further information on testing and on the evaluation of test results Image

    NOTE 3 The National Annex may give conversion factors for existing test results to be equivalent to the outcome of standardised tests according to this annex.

  2. This annex covers:

A.2 Tests on profiled sheets

A.2.1 General

  1. Loading may be applied through air bags or in a vacuum chamber or by metal or timber cross beams arranged to simulate uniformly distributed loading.
  2. To prevent spreading of corrugations, transverse ties or other appropriate test accessories such as timber blocks may be applied to the test specimen. Some examples are given in Figure A.1.
  3. Test specimens for sheet profiles should normally comprise at least two complete corrugations, but a test specimen may comprise just one complete corrugation, provided that the stiffness of the corrugations is sufficient. Free longitudinal edges should be in the tension zone during test procedure.

    Figure A.1 - Examples of appropriate test accessories

    Figure A.1 - Examples of appropriate test accessories

  4. For uplift tests, the test set-up should realistically simulate the behaviour of the sheeting under practical conditions. The type of joints between the sheet and the supports should be the same as in the joints to be used in practice.
  5. To give the results a wide range of applicability, hinged and roller supports should preferably be used, to avoid any influence of torsional or longitudinal restraint at the supports on the test results. 53
  6. It should be ensured that the direction of the loading remains perpendicular to the initial plane of the sheet throughout the test procedure.
  7. To eliminate the deformations of the supports, the deflections at both ends of the test specimen should also be measured.
  8. The test result should be taken as the maximum value of the loading applied to the specimen either coincident with failure or immediately prior to failure as appropriate.

A.2.2 Single span test

  1. A test set-up equivalent to that shown in Figure A.2 may be used to determine the midspan moment resistance (in the absence of shear force) and the effective flexural stiffness.
  2. The span should be chosen such that the test results represent the moment resistance of the sheet.
  3. The moment resistance should be determined from the test result.
  4. The flexural stiffness should be determined from a plot of the load-deflection behaviour.

A.2.3 Double span test

  1. The test set-up shown in Figure A.3 may be used to determine the resistance of a sheet that is continuous over two or more spans to combinations of moment and shear at internal supports, and its resistance to combined moment and support reaction for a given support width.
  2. The loading should preferably be uniformly distributed (applied using an air bag or a vacuum chamber, for example).
  3. Alternatively any number of line loads (transverse to the span) may be used, arranged to produce internal moments and forces that are appropriate to represent the effects of uniformly distributed loading. Some examples of suitable arrangements are shown in Figure A.4.

A.2.4 Internal support test

  1. As an alternative to A.2.3, the test set-up shown in Figure A.5 may be used to determine the resistance of a sheet that is continuous over two or more spans to combinations of moment and shear at internal supports, and its resistance to combined moment and support reaction for a given support width.
  2. The test span s used to represent the portion of the sheet between the points of contraflexure each side of the internal support, in a sheet continuous over two equal spans L may be obtained from:

    s = 0,4 L     (A.1)

  3. If plastic redistribution of the support moment is expected, the test span s should be reduced to represent the appropriate ratio of support moment to shear force.
  4. The width bB of the beam used to apply the test load should be selected to represent the actual support width to be used in practice.
  5. Each test result may be used to represent the resistance to combined bending moment and support reaction (or shear force) for a given span and a given support width. To obtain information about the interaction of bending moment and support reaction, tests should be carried out for several different spans.
54

Figure A.2 - Test set-up for single span tests

Figure A.2 - Test set-up for single span tests

Figure A.3 - Test setup for double span tests

Figure A.3 - Test setup for double span tests

Figure A.4 - Examples of suitable arrangements of alternative line loads

Figure A.4 - Examples of suitable arrangements of alternative line loads

55

Figure A.5 - Test set-up for internal support test

Figure A.5 - Test set-up for internal support test

Figure A.6 - Test set-up for end support tests

Figure A.6 - Test set-up for end support tests

A.2.5 End support test

  1. The test set-up shown in Figure A.6 may be used to determine the resistance of a sheet at an end support.
  2. Separate tests should be carried out to determine the shear resistance of the sheet for different lengths u from the contact point at the inner edge of the end support, to the actual end of the sheet, see Figure A.6.
56

A.3 Evaluation of test results

A.3.1 General

  1. A specimen under test should be regarded as having failed if the applied test loads reach their maximum values, or if the gross deformations exceed specified limits.
  2. In the testing of joints, or of components in which the examination of large deformations is necessary for accurate assessment (for example, in evaluating the moment-rotation characteristics of sleeves), no limit need be placed on the gross deformation during the test.
  3. An appropriate margin of safety should be available between a ductile failure mode and possible brittle failure modes. As brittle failure modes do not usually appear in large-scale tests, additional detail tests should be carried out where necessary.

    NOTE This is often the case for joints.

A.3.2 Adjustment of test results

  1. Test results should be appropriately adjusted to allow for variations between the actual measured properties of the test specimens and their nominal values.
  2. The actual measured 0,2 % proof strength f0,2,obs should not deviate by more than ± 25% from the nominal 0,2 % proof strength f0,2.
  3. The actual measured material thickness tobs should not exceed the design thickness t based on the nominal material thickness tnom by more than 12%.
  4. Adjustments should be made in respect of the actual measured values of the material thickness tobs and the 0,2 % proof strength f0,2,obs all tests, except where the design expression that uses the test results also uses the actual measured value of the thickness or 0,2 % proof strength of the material, as appropriate.
  5. The adjusted value Radj,i of the test result for test i should be determined from the actual measured test result Robs,i using:

    Radj,i = Robs,i / μR     (A.2)

    in which μR is the resistance adjustment coefficient given by:

    Image

  6. The exponent α for use in expression (A.2) should be obtained as follows:
  7. The exponent β for use in expression (A.2) should be obtained as follows:
57

A.3.3 Characteristic values

A.3.3.1 General
  1. Characteristic values may be determined statistically, provided that there are at least 4 test results.

    NOTE A larger number is generally preferable, particularly if the scatter is relatively wide.

  2. The characteristic minimum value should be determined using the following provisions. If the characteristic maximum value or the characteristic mean value is required, it should be determined by using appropriate adaptations of the provisions given for the characteristic minimum value.
  3. The characteristic value of a resistance Rk determined on the basis of at least 4 tests may be obtained from:

    Rk = Rmk s     (A.4)

    where:

    s is the standard deviation;
    k is the appropriate coefficient from Table A.1;
    Rm is the mean value of the adjusted test results Radj.
  4. The standard deviation s may be determined using:

    Image

    where:

    Radj,i adjusted test result for test i;
    n is the number of tests.
    Table A.1 - Values of the coefficient k
    n 4 5 6 8 10 20 30
    k 2,63 2,33 2,18 2,00 1,92 1,76 1,73 1,64
A.3.3.2 Characteristic values for families of tests
  1. A series of tests carried out on a number of otherwise similar sheets, in which one or more parameters is varied, may be treated as a single family of tests, provided that they all have the same failure mode. The parameters that are varied may include cross-sectional dimensions, spans, thicknesses and material strengths.
  2. The characteristic resistances of the members of a family may be determined on the basis of a suitable design expression that relates the test results to all the relevant parameters. This design expression may either be based on the appropriate equations of structural mechanics, or determined on an empirical basis.
  3. The design expression should be modified to predict the mean measured resistance as accurately as practicable, by adjusting the coefficients to optimise the correlation.

    NOTE Information on this process is given in Annex D of EN 1990.

  4. In order to calculate the standard deviation s, each test result should first be normalized by dividing it by the corresponding value predicted by the design expression. If the design expression has been modified as specified in (3), the mean value of the normalized test results will be unity. The number of tests n should be taken as equal to the total number of tests in the family. 58
  5. For a family of at least four tests, the characteristic resistance Rk should then be obtained from expression (A.3) by talking Rm as equal to the value predicted by the design expression, and using the value of k from Table A.1 corresponding to a value of n equal to the total number of tests in the family.

A.3.4 Design values

  1. The design value of a resistance Rd should be derived from the corresponding characteristic value Rk determined by testing, using:

    Rd = Rk / (γM γsys)     (A.6)

    where:

    γM is the partial factor for resistance;
    γsys is a partial factor for differences in behaviour under test conditions and service conditions.
  2. For a family of at least four tests, the value of γM may be determined using statistical methods.

    NOTE Information on an appropriate method is given in Annex D of EN 1990.

  3. Alternatively γM may be taken as equal to the appropriate value of γM for design by calculation given in Section 2.

    NOTE The National Annex may give values for γM and γsys. A recommended value for γsys is 1,0 in case of sheeting.

  4. For other types of tests in which possible instability phenomena, or modes of behaviour, of structures or structural components might not be covered sufficiently by the tests, the value of γsys should be assessed taking into account the actual testing conditions, in order to achieve the necessary reliability.

A.3.5 Serviceability

  1. The provisions given in Section 7 should be satisfied.
59

Annex B – Durability of fasteners

[informative]

  1. For mechanical joints in cold-formed sheeting Table B.1 may be applied
    Table B.1 - Fastener material with regard to corrosion environment (and sheeting material only for information). Only risk of corrosion is considered. Environmental corrosivity categories according to EN ISO 12944-2
    Corrosivity category Sheet material Material of fastener
    Aluminium Electro galvanized steel. Coat thickness ≥ 7μm Hot-dip zinc coated steel b. Coat thickness ≥ 45μm Stainless steel, case hardened. 1.4006 d,e Stainless steel, 1.4301 d 1.4436 d Monel a
    C1 A, B, C
    D, E, S
    X
    X
    X
    X
    X
    X
    X
    X
    X
    X
    X
    X
    C2 A
    C, D, E
    S
    X
    X
    X
    -
    -
    -
    X
    X
    X
    X
    X
    X
    X
    X
    X
    X
    X
    X
    C3 A
    C, E
    D
    S
    X
    X
    X
    -
    -
    -
    -
    -
    X
    X
    X
    X
    -
    (X)c
    -
    X
    X
    (X)c
    (X)c
    X
    X
    -
    X
    X
    C4 A
    D
    E
    S
    X
    -
    X
    -
    -
    -
    -
    -
    (X)c
    X
    X
    X
    -
    -
    -
    -
    (X)c
    (X)c
    (X)c
    X
    -
    -
    -
    X
    C5-I A
    Df
    S
    X
    -
    -
    -
    -
    -
    -
    X
    -
    -
    -
    -
    (X)c
    (X)c
    X
    -
    -
    -
    C5-M A
    Df
    S
    X
    -
    -
    -
    -
    -
    -
    X
    -
    -
    -
    -
    (X)c
    (X)c
    X
    -
    -
    -

    NOTE Fastener of steel without coating may be used in corrosivity category CI.

    A = aluminium irrespective of surface finish
    B = un-coated steel sheet
    C = hot-dip zinc coated (Z275) or aluzinc coated (AZ150) steel sheet
    D = hot-dip zinc coated + coating of paint or plastic
    E = aluzinc coated (AZ185) steel sheet
    S = stainless steel
    X = type of material recommended from corrosion standpoint
    (X) = type of material recommended from corrosion standpoint under the specified condition only
    - = type of material not recommended from corrosion standpoint
    a refers to rivets only
    b refers to screws and nuts only
    c insulation washer of material resistant to aging between sheeting and fastener
    d stainless steel EN 10 088
    e risk of discoloration
    f always check with sheet supplier
  2. The environmental corrosivity categories following EN ISO 12944-2 are presented in Table B.2. 60
    Table B.2 - Atmospheric-corroslvity categories according to EN ISO 12944-2 and example of typical environment
    Corrosivity category Corrosivity level Example of typical environments in temperature climate (informative)
    Exterior Interior
    CI very low - Heated buildings with clean atmospheres, e.g. offices, shops, schools, hotels.
    C2 low Atmospheres with low level of pollution. Mostly rural areas. Unheated buildings where condensation may occur, e.g. depots, sport halls.
    C3 medium Urban and industrial atmospheres, moderate sulphur dioxide pollution. Coastal areas with low salinity. Production rooms with high humidity and some air pollution, e.g. food-processing, plants, laundries, breweries and dairies.
    C4 high Industrial areas and coastal areas with moderate salinity. Chemical plants, swimming pools, coastal ship- and boatyards.
    C5-I very high (industrial) Industrial areas with high humidity and aggressive atmospheres. Buildings and areas with almost permanent condensation and with high pollution.
    C5-M very high (marine) Coastal and offshore areas with high salinity. Buildings and areas with almost permanent condensation and with high pollution
61

Bibliography

  1. Weber, H.: Dach und Wand - Panen und Bauen mit Aluminium-Profiltafeln; Aluminium-Verlag-Düsseldorf 1982 (in German)
  2. Richtlinie für die Verlegung von Aluminium-Profiltafeln; Aluminium-Merkblatt A7; Gesamtverband der Aluminiumindustrie, Düsseldorf 1995 (in German)
  3. Verbindungen Profiltafeln und dünnwandigen Bauteilen aus Aluminium; Aluminium-Merkblatt A9; Gesamtverband der Aluminiumindustrie, Düsseldorf 1995 (in German)
  4. SFHF-Richtlinien für hinterlüftete Fassaden - Grundsätze für Planung, Bemessung, Konstruktion und Ausführung; Schweizerischer Fachverband für hinterlüftete Fassaden; Zürich 1992 (in German and French)
  5. Directives APSFV pour façades ventilées; Principes et remarques pour l’étude, le dimensionnement, la construction et l’exécution; Association professionnelle suisse pour des façades ventilées (in French and German)
  6. Aluminium-Trapezprofile und ihre Verbindungen - Kommentar zur Anwendung und Konstruktion. Gesamtverband der Aluminiumindustrie e.V. Am Bonneshof 5, D-40 474 Düsseldorf.
  7. Baehre, R., Wolfram, R.: Zur Schubfeldberechnung von Trapezprofilen Stahlbau 6/1986, S. 175-179
  8. Baehre, R., Huck, G.: Zur Berechnung der aufnehmbaren Normalkraft von Stahl- Trapezprofilen nach DIN 18807 Teile 1 und 3, Stahlbau 69 (1990), Heft 8, S. 225 - 232
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