recommendations for the design, detailing and application ...en 14509-2 25 6. resistance determined...

European Recommendations for the Design, Detailing and Application of Fastenings for Sandwich Panels

Publication

418

ECCS TC7 TWG7.9Sandwich Panels and related Structures

CIB Working Commission W056Sandwich Panels

European Recommendations for theDesign, Detailing and Application of

Fastenings for Sandwich Panels1st Edition, 2019

Title European Recommendations for the Design, Detailing and Application of Fastenings for Sandwich Panels

Serial title 418

Year 1st edition, 2019

Authors Wim Bakens, Ivan Balazs, Andrej Belica, Klaus Berner, Nicholas Brown, Sebastien Charton, JM Davies, Mircea Georgescu, Paavo Hassinen, Simo Heikkilä, Antti Helenius, Lars Heselius, David Izabel, Karsten Kathage, Saskia Käpplein, Jörg Lange, Philip Leach, Jan-Christer Mäki, Thomas Misiek, Youcef Mokrani, Bernd Naujoks, Ute Pfaff, Lars Pfeiffer, Ralf Podleschny, Zbigniew Pozorski, Kari Rantakylä, Keith Roberts, Daniel Ruff, Helmut Saal, Johan Schedin, Robert Xiao, Danijel Zupancic Language English Pages 114 p. Key words Sandwich panels, Fastenings, Engineering Design, Screws ISBN 978-9063-63-09-73 Publisher CIB General Secretariat

Van der Burghweg 1 2628 CS, Delft

The Netherlands E-mail [email protected] www.cibworld.nl

All rights reserved. No parts of this publication may be reproduced, stored in a retrieval system, or

transmitted in any form or by any means, electronic, mechanical, photocopying, recording or other-

wise, without the prior permission of the copy-right owner

CIB assumes no liability regarding the use for any application of the material and information con-

tained in this publication.

Copyright © 2019 CIB – International Council for Research and Innovation in Building and Con-

struction

Photo cover credits Matthias Möldner (EJOT Baubefestigungen GmbH, Bad Laasphe, Germany)

mailto:[email protected]

http://www.cibworld.nl/

European Recommendations for the Design, Detailing and Application of Fastenings for Sandwich Panels | II

PREFACE

PREFACE

This document provides the guidance on design, detailing and application of fas-tenings for sandwich panels. As the current and existing “Preliminary EuropeanRecommendations for testing and design of fastenings for sandwich panels” hasbeen mainly written from the manufacturer’s point of view that focuses more on thedetermination of resistance values against the test results. This document will pro-vide guidance for designers and contractors and therefore is focusing more onloads and actions on fastenings of sandwich panels. For readers interested in thebackground information, references to other publications are given, for example toother ERs, standards or scientific papers.

This document has been prepared by the Joint Committee of ECCS TC7 TWG7.9and CIB Working Commission W056. The members of the Joint Committee whocontributed to the document are:

Wim Bakens NetherlandsIvan Balazs Czech RepublicAndrej Belica LuxemburgKlaus Berner GermanyNicholas Brown AustraliaSebastien Charton FranceJM Davies UKMircea Georgescu RomaniaPaavo Hassinen FinlandSimo Heikkilä FinlandAntti Helenius FinlandLars Heselius FinlandDavid Izabel FranceKarsten Kathage GermanySaskia Käpplein GermanyJörg Lange GermanyPhilip Leach UKJan-Christer Mäki SwedenThomas Misiek Germany

III | European Recommendations for the Design, Detailing and Application of Fastenings for Sandwich PanelsPREFACE

Youcef Mokrani FranceBernd Naujoks GermanyUte Pfaff GermanyLars Pfeiffer GermanyRalf Podleschny GermanyZbigniew Pozorski PolandKari Rantakylä FinlandKeith Roberts UKDaniel Ruff GermanyHelmut Saal GermanyJohan Schedin BelgiumRobert Xiao UKDanijel Zupancic Slovenia

European Recommendations for the Design, Detailing and Application of Fastenings for Sandwich Panels | IV

SYMBOLOGY

NOTATION

NEd design value of the tensile forceVEd design value of the shear forceNRk characteristic value of the tensile

resistanceVRk characteristic value of the shear

resistancemax u maximum allowable value of

head deflectionNRd design value of the tensile re-

sistanceVRd design value of the shear re-

sistance

D overall depth of the paneldC continuous depth of the panel

core material, dc = D - (tF1 + tF2)DF distance between top of support-

ing structure and top of externalface at point of fastening

b1 width of the ribs of the externalface (see EN 14509)

tF1 design sheet thickness of the ex-ternal face

tF2 design sheet thickness of the in-ternal face

tII design sheet thickness of thesupporting structure

tnom,F1 nominal sheet thickness of theexternal face

tnom,F2 nominal sheet thickness of theinternal face

tnom,II nominal sheet thickness of thesupporting structure

ECc compression modulus of the corefCc compression strength of the corefu,F1 tensile strength of the external

facefu,F2 tensile strength of the internal

facefu,II tensile strength of the supporting

structured external thread diameter of the

screw, usually the nominal diame-ter

d0 diameter of the holedW diameter of washerdpd self-drilling screw: max (d1, ddp) self-tapping screw: predrilling di-

ameterd1 core diameter of the threadddp diameter of drill-pointdef effective diameterP pitch of the thread

fu,SG tensile strength of the materialof the screw

as,SG ratio of shear to tensilestrength

FAs,SG Load-bearing capacity of thethread of the screw

FAs,MG Load-bearing capacity of theinside thread in the supportingstructure

R(AMG,SG) Reduction divisor forcombined failure in both threads

t1 is the smaller of the thickness ofthe timber side member or the

V | European Recommendations for the Design, Detailing and Application of Fastenings for Sandwich PanelsSYMBOLOGY

penetration depthnef effective number of fastenerslef effective length, penetration

length of the thread, lef = lg - lblg screw-in length - part of thread

into component II including lengthof drill point

lb length of unthreaded part of thedrill point

My,Rk characteristic yield moment offastener

Fax,Rk characteristic axial withdrawalcapacity of the fastener

Fv,Rk characteristic shear capacity of

the fastener

fax,k characteristic withdrawal strengthperpendicular to the direction ofgrain

fh,k characteristic embedmentstrength of timber member

a angle between the force and thedirection of grain

rk characteristic densityra associated density related to fax,k,

usually ra = 350 kg/m³ for timberof strength grade C24 as refer-ence density

European Recommendations for the Design, Detailing and Application of Fastenings for Sandwich Panels | VI

CONTENTS

CONTENTS

1. INTRODUCTION AND APPLICATION RANGE 12. DEFINITIONS 33. MATERIALS AND DURABILITY 5

3.1 Introduction to materials 53.1.1 Carbon steel 53.1.2 Stainless steel 5

3.2 Choice of materials 64. DESIGN OF FASTENINGS 9

4.1 Actions and loads 94.2 Resistance of fastenings 134.3 Design of fastenings 15

5. RESISTANCE DETERMINED BY TESTS 195.1 General 195.2 Design based on an approval for fasteners 19

5.2.1 Sandwich panels on steel or aluminium supportingstructures 19

5.2.2 Sandwich panels on timber supporting structures 225.3 Design based on an approval for sandwich panels or

EN 14509-2 256. RESISTANCE DETERMINED BY CALCULATION 29

6.1 Application range 296.2 Pull-through resistance 29

6.2.1 Background 29

6.2.2 Design procedures for sandwich panels with steelfaces 29

VII | European Recommendations for the Design, Detailing and Application of Fastenings for Sandwich PanelsCONTENTS

6.3 Pull-out resistance 316.3.1 Background 31

6.3.2 Design procedures for steel and aluminium support-ing structures 31

6.3.3 Design procedures for timber supporting structures 356.4 Shear resistance 38

6.4.1 Background 38

6.4.2 Design procedures for sandwich panels with steelfaces

396.4.3 Design procedures for sandwich panels with alumini-

um faces 40

6.4.4 Additional design procedures for timber supportingstructures supporting structures

406.5 Head deflection 45

6.5.1 Background 456.5.2 Design equations for steel, aluminium and timber

supporting structures 457. EXECUTION AND MAINTENANCE 47

7.1 General 477.2 Layout drawings 477.3 Product and procedure testing 477.4 Installation personell 477.5 Head deflection 48

7.5.1 Alignment of sandwich panels 487.5.2 Fasteners and tools 487.5.3 Position and inclination of fasteners 487.5.4 Tightening of fasteners 49

7.6 Maintenance 50REFERENCES 51ANNEX A: HEAD DEFLECTION 59

A.1 Mechanisms which cause head deflections 59A.2 Analytical calculation procedures for single span panels 61

A.2.1 General parameters 61A.2.2 Sandwich panels with flat or lightly profiled faces 62A.2.3 Sandwich panels with profiled faces 63

European Recommendations for the Design, Detailing and Application of Fastenings for Sandwich Panels | VIII

CONTENTS

A.3 Analytical calculation procedures for multi-span panels 64A.4 Approximate calculation for single or multi-span panels with

flat or profiled faces 65ANNEX B: TRANSVERSE COMPRESSION DEFORMATION 67

B.1 Calculation of deformation 67B.2 Detailing requirements 67

ANNEX C: DESIGN EXAMPLES 69C.1 Background information 69C.2 Wall panel 69

C.2.1 System 69C.2.2 Actions and loads 70C.2.3 Characteristic values of support reactions 71C.2.4 Design values of support reactions 72C.2.5 Head deflection 73C.2.6 Resistance and verifications 74

C.3 Roof panel 80C.3.1 System 80C.3.2 Actions and loads 81C.3.3 Characteristic values of support reactions 83C.3.4 Design values of support reactions 85C.3.5 Head deflection 86C.3.6 Resistance and verifications 88

C.4 Roof panel 95C.4.1 System 95C.4.2 Actions and loads 96C.4.3 Characteristic values of support reactions 96C.4.4 Design values of support reactions 96C.4.5 Head deflection 98C.4.6 Resistance and verifications 98

IX | European Recommendations for the Design, Detailing and Application of Fastenings for Sandwich PanelsCONTENTS

European Recommendations for the Design, Detailing and Application of Fastenings for Sandwich Panels | 1

1 INTRODUCTION AND APPLICATION RANGE


Sandwich panels for building applications are usually fastened to a supportingstructure made of steel, aluminium, timber (including wood-based materials), eachof different cross-sectional shapes and manufacturing processes1. For fastening toconcrete cast-in steel channels are often used. As a consequence, self-drillingscrews and self-tapping screws are the preferred fasteners for fastening of sand-wich panels to the supporting structure. Fasteners such as blind rivets or cartridge-fired pins are not covered by this document. Direct fastening to concrete is doneusing concrete screws or spikes driven into predrilled holes. In any case, sealingwashers are used to increase resistance and to obtain tight fastenings.For non-structural components fastened to the faces of sandwich panels see the"European Recommendations for the Design of Sandwich Panels with Point orLine Loads".The type and material of the fastener and the washer have to be chosen depend-ing on application, material of the supporting structure and corrosivity category ofthe surrounding environment. As fasteners and washers are usually exposed toweather and other environmental conditions, fasteners and washers are usuallymade of stainless steel: This document will start with some basic information ondurability of different materials for fasteners.Only then the basics of design of fasteners are introduced. Design values of re-sistance may be obtained from tests or calculated using design formulae. To allowfor general application of this introductory chapter, source of applied design valuesof resistance is left open here.These values and their sources are introduced in two following chapters, distin-guishing between values based on tests and values determined by calculation.Finally, information on performance of fasteners, on execution and maintenance isgiven, to allow for proper installation guaranteeing safety in accordance to eitherEuropean or national provisions for load-bearing capacity but also serviceability.

1 The presentation of the supporting structures both in the text or figures must inevitably be limitedto exemplary cross-sectional shapes and manufacturing processes. However, unless explicitlymentioned in individual cases, this does not result in any general limitation with regard to the scopeof application of these recommendations.

2 | European Recommendations for the Design, Detailing and Application of Fastenings for Sandwich Panels



2 DEFINITIONS

2 DEFINITIONS

fastener connecting element in a fasteningfastening interaction of fastener with surrounding materialconnection group (one or more) of fastenerscomponent I the component which is next to the head of the fas-

tening screw, usually the sandwich panel to be fastenedcomponent II the component which is opposite to the head of the fas-

tening screw, usually the supporting structuredirect fastening fastening of sandwich panels which penetrates both

faces of the panel (through fastening). The fastenershead is visible. Direct fastenings are sometimes referredto as visible fastenings.

hidden fastening fastening of sandwich panels along their longitudinaljoints, taking advantage of the geometry of the joint. Thefastening is not visible. If no adapter plates are used(through fastening), the fastener is penetrating the panelsometimes also using a steel plate under the head ofthe fastener for increase of pull-through resistance. Ifadapter plates are used, the fastener is referred to asindirect fastening. Hidden fastenings are often referredto as concealed fastenings.

indirect fastening fastening using special adapter plates, screw is notpenetrating the panel, usually a hidden fastening, i.e.fastening is hidden in the longitudinal joint between ad-jacent panels.

sealing washer annular washer with vulcanized sealing usually made ofEPDM

saddle washer prismatic washer for crest-fastening of panels with pro-filed faces. The width corresponds to the width of the ribof the external face. Saddle washers are usually provid-ed with a rubber foam sealing.

self-drilling screw screws with a drill-point so that the drilling of the hole,the tapping of the female and screwing-in is done in oneoperating sequence

self-tapping screw screw which taps the female thread in an existing holei.e. self-tapping screws require pre-drilling.

concrete screw hardened screw for fastening to concrete structures,often double-threaded, taps a thread into the concrete


2 DEFINITIONS

(no plug), i.e. requires pre-drilling.concrete nail crooked nail for fastening to concrete structures,

mounted by hammering, requires pre-drilling.


3 MATERIALS AND DURABILITY


3.1 Introduction to materials

3.1.1 Carbon steelCarbon steel screws are usually made of case-hardened steel or of heat-treatablesteel. Because of heat treatment, carbon steel fasteners provide a high strengthand hardness. The high hardness values are accompanied by the risk of hydrogenembrittlement.For carbon steel screws corrosion protection is required. Most common type ofcorrosion protection is done by galvanic zinc plating according to EN ISO 4042. Itshould be highlighted that fasteners listed in a European technical approval usuallyhave a zinc coating specified as A3K which means that the fasteners are zinc-plated with a coating thickness ≥ 8 µm. Care should be taken that a lower coatingthickness shall not be used, see EN 1993-1-3, Annex B.In addition, zinc flake coating systems are used. These coatings have an organicor inorganic matrix with dispersed zinc- and aluminium particles. Unfortunatelythese coatings may be damaged during transport or by abrasion during installation,if not even scraped off. Therefore an assessment of such coatings is difficult butnevertheless necessary for verification of suitability of a coating for a corrosivitycategory (see EN 1993-1-3, Annex B for corrosivity category of environment).

3.1.2 Stainless steel3.1.2.1 Preliminary remarksStainless steels for screws can be classified according to the system given in ENISO 3506-4. The mechanical properties which can be achieved depend on thesteel group (austenitic, martensitic or ferritic stainless steel). Stainless steels ob-tain their corrosion resistance by a passive layer of chromium oxide.3.1.2.2 Austenitic stainless steelDesignations such as the steel grades A2 (e.g. 1.4301 or 1.4567) and A4 (e.g.1.4401 or 1.4578) for austenitic stainless steels are quite familiar and refer pre-dominantly to the corrosion resistance. Austenitic stainless steels cannot be hard-ened by heat-treatment but by cold working. Increasing of surface hardness bynitriding is also possible. If self-drilling screws for drilling into steel are required adrill-point made of hardened carbon steel has to be welded to the screw’s tip. Afterinstallation just the stainless steel part of the screw will be a part of the load-bearing system and not the welded on drill-point.3.1.2.3 Martensitic stainless steelMartensitic stainless steels can be heat treated which allows producing self-drilling



screws in one part with a drill-point which has not to be welded on. Corrosion re-sistance is considerably lower than for austenitic stainless steel and high hardnessafter heat treatment makes them vulnerable to hydrogen embrittlement and stresscorrosion cracking.

3.2 Choice of materials with respect to corrosion

Choice of material has to be made depending on the material of the structuralparts to be connected, taking into account both corrosivity of the surrounding andthe intended service life. Most important factor is corrosion which is also influencedby the material of the parts to be connected. It has to be mentioned that the highstrength of the fasteners does not have a significant effect on the resistance of theconnection, because with thin-walled sheeting and sections, failure of the buildingcomponents to be connected is the governing parameter. Stressing by forcestherefore normally does not become decisive for the choice of material for the fas-teners.Corrosivity of the surrounding depends on moisture conditions, air pollution (dustwhich may dissolve in water, chloride in industrial and marine environment or fromroad de-icing salts, sulphur dioxide exhausted from power plants and traffic etc.)and time of exposure. Moisture may have access to the screws by weather, butalso by condensation at thermal bridges. Some thermal insulation materials suchas mineral wool are able to work like a sponge, absorbing water. If screws are in-stalled through a sandwich panel with soaked mineral wool, corrosion is directlyaffecting the load-bearing part of the screw. It is also important if conditions mayget worse by accumulation of corrosive agents. Typical example is the accumula-tion of both corrosive agents such as de-icing salt and moisture behind externalwalls ventilated at rear. On the other hand, occasional rain may even have a clean-ing effect on the screw. So detailing is also a very important consideration.

The following recommendations are backed by a long-time experience:- Screws completely or partly exposed to weather or comparable moisture

conditions shall be made of austenitic stainless steel. This does not refer towelded drill points, but it has to be checked that the screw-in length is bigenough so that carbon steel parts are not part of the load-bearing system.

- The period of construction shall be taken into account, also with respect oftime of construction.

- In applications, where concentrations of corrosive agents may accumulateor surroundings with higher corrosivity, austenitic stainless steels of highergrades (for example A4) are necessary. This may be the case with screws



in the cavity or clear space of external walls ventilated at rear or otherwiseshielded from direct rain and a regular cleaning is not foreseen or not possi-ble. A good assistance for choosing the right stainless steel grade regardingcorrosion resistance for fastening elements offers EN 1993-1-4/A1, AnnexA.

- Screws made of carbon steel or martensitic stainless steel are not suitablein case that minimum requirements on corrosion resistance exist, see EN1993-1-3, Annex B. Carbon steel screws, including electrolytically galva-nized or coated fasteners, and screws made of martensitic stainless steelshall only be used where moisture does not affect them. This covers:

· fastening of internal shells of multi-shell roof and wall structures(decking profiles or cassettes) of dry and predominantly closedrooms, provided the external shell prevents entry and accumulationof corrosive agents and rain (external shell made of sheeting).

· fastening of decking profiles of unventilated single shell roofs of dryand predominantly closed rooms with insulation on the external side(typical flat roof applications with insulation membranes)

· ceiling systems over dry and predominantly closed rooms- Fastening of aluminium sheeting shall only be done with screws made of

stainless steel except in heavy maritime environments. In this case addi-tional protection measures of the connections are required.

- Galvanic corrosion shall be taken into account when designing and detailingstructures, see EN 1090-4, Annex E or EN 1090-5, Annex E.

- While repeated bending of fasteners due to thermal elongation and move-ment usually becomes not decisive for design of austenitic stainless steelfasteners, care should be taken when using hardened martensitic or carbonsteel screws.


4 DESIGN OF FASTENINGS


4.1 Actions and loads

Shear forces in fasteners are mainly caused by self-weight loading2 of the panel orroof thrust caused by self-weight or snow (Fig. 4.1). Other possible sources areforces from lateral stabilisation of the supporting beams, purlins or rails (see ECCSpublication no. 135/CIB publication no. 379 (2014)), diaphragm action (includingseismic actions) or forces from restraint thermal movements. The design value ofthe shear force caused by action effects is denoted with VEd. Determination of ac-tion effects is based on the different parts of EN 1991. For a complete overview onactions acting on sandwich panels see ECCS publication no. 136/CIB publicationno. 401 (2015).Shear loads in connections are predominantly transferred by the internal face ofthe panel (tF2), therefore failure occurs by elongation of the hole in the internalface. Tilting of the fastener is prevented by sandwich panel itself. With the usualsheet thicknesses of sandwich panels, shear failure of the fastener itself rarely oc-curs.

Fig. 4.1: Shear forces in fasteners caused by self-weight and roof thrust

Tensile forces in fasteners are predominantly caused by wind suction (Fig. 4.2) or

2 Self-weight loading of wall panels may also be transferred via support angles at base points orabove large openings by reinforced girts.



restraint thermal deformation (Fig. 4.3). Other possible sources for tensile forcesare forces from torsional stabilisation of the supporting beams, purlins or rails, seeECCS publication no. 135/CIB publication no. 379 (2014) or inertia forces causedby seismic actions. The design value of the tensile force caused by action effectsis denoted with NEd. Determination of action effects is based on the different partsof EN 1991. For normal applications increased action effects from wind gusts neednot to be taken into account when calculating the action effects. These are usuallyconsidered when determining the resistance values and therefore covered by theresistance values, see ECCS publication no. 127/CIB publication no. 320 (2009).EN 14509 gives additional information on temperature loads. For a complete over-view on actions acting on sandwich panels see ECCS publication no. 136/CIB pub-lication no. 401 (2015).Possible failure modes are pull-out failure from the supporting structure (tII) or pull-over/pull-through failure through the external face of the panel (tF1). With the usualsheet thicknesses of sandwich panels, tensile failure of the fastener itself rarelyoccurs.

Fig. 4.2: Tensile forces in fasteners caused by wind



Fig. 4.3: Deflection of the fasteners and tensile forces in fasteners caused by restraint thermal de-formation (here: summer design situation)

Temperature differences DT of the surface temperatures of the internal and exter-nal face (Fig. 4.4) cause thermal movement of the panel. This includes shear de-formations and rotation at supports. As temperature of the external face changesfrom night to day, temperature differences do so as well. The repeated changeslead to repeated deformations and rotations at supports causing a repeatedmovement of the fasteners (head displacement u). The fastening is thereforeprone to fatigue failure. Although the head deflection corresponds to a cyclic load,the action effect is usually denoted with u and calculated using a partial safety fac-tor of gFf = 1.0. EN 14509 gives additional information on temperature loads. For acomplete overview on actions and loads acting on sandwich panels, see ECCSpublication no. 136/CIB publication no. 401 (2015).The load spectrum caused by the change of temperature difference and the num-ber of cycles are taken into account when determining the resistance values andare therefore covered by the resistance values, see ECCS publication no. 127/CIBpublication no. 320 (2009).Fatigue failure can be observed as unwinding from the supporting structure (tII),reduced pull-out resistance from the supporting structure (tII) or cracking of the fas-tener itself.



Fig. 4.4: Deflection u of the head of the fasteners caused by restraint thermal deformation

Exposure of roof panels to high snow loads might lead to a transverse compres-sion deformation (shortening) of the core material at supports. This might cause agap between the external face and the washer or an improperly compressed seal-ing, both causing leakage. Roof panels with indirect fastenings or wall panels ingeneral are not affected. Some national regulations and/or customers requirechecking the value of transverse compression deformation, for example for alti-tudes above 1000 m (see also EN 1991-1-3). The verifications may be done usingthe formulas and requirements given in Annex B. See RAGE (2014a) for furtherrequirements and additional verifications.

Fig. 4.5: Transverse compression deformation caused by high snow loads

The tensile and shear loads in fastenings shall be calculated for ultimate limit state(ULS) using the theory of elasticity. This approach is different to the one used in



the design of the panels itself, where plastic hinges at intermediate supports areusually assumed for ULS design (see EN 14509, chapter E.7.2.1). If this would bedone in design of fastenings, tensile forces caused by restraint thermal defor-mation would be supressed. See references for detailed information on structuralanalysis of sandwich panels. For ULS, the combination according to Eq. (4.1) ap-plies.

åå>³

××+×+×=1

,,0,1,1,1

,,i

ikiiQkQj

jkjGd QQGE yggg

Eq. (4.1)

The value of head deflection shall be calculated for fatigue limit state (FLS) usingthe formulas given in Annex A and a characteristic value of temperature differenceof DT = T2 - T1 = -70 K only. This value is based on an assumed installation tem-perature of 10° C and a temperature of the outer face of 80° C. The later assump-tion is conservative and has become firmly established as good practice.The value of transverse compression deformation of the core at supports shall becalculated for serviceability limit state (SLS) using the theory of elasticity for calcu-lation of support reactions and by means of the compressive modulus ECc accord-ing to EN 14509. For SLS, the characteristic (rare) combination according to Eq.(4.2) applies.

1,1

, kj

jkd QGE += å³

Eq. (4.2)

where Qk,1 is the characteristic value of actions caused by snow load. For the rarecombination, creep effects do not need to be considered.

4.2 Resistance of fastenings

The characteristic resistance values are denoted as followsNRk,I: characteristic value of pull-through resistanceNRk,II: characteristic value of pull-out resistanceVRk,I: characteristic value of shear resistance of the internal faceVRk,II: characteristic value of shear resistance of the supporting structureuRk: characteristic value of allowable head deflectionwS,Ck: characteristic value of allowable transverse compression deformation



The characteristic values of tensile and shear resistance are defined as

{ }IIRkIRkRk NNN ,, ;min=

Eq. (4.3)

and

{ }IIRkIRkRk VVV ,, ;min=

Eq. (4.4)

respectively. Failure of the fastener itself is usually covered by the resistance re-lated to component II, however it will not become decisive with usual applicationsin sandwich panels.The resistance values can be determined by tests (see chapter 5) or by calculation(see chapter 6 and table 4.1).

Table 4.1: Resistance determined by calculation – overview of chapter 6

Resistance ComponentMaterial of supporting structure

Steel Aluminium Timber

NR,k

I 6.2.2

II 6.3.2 6.3.2 6.3.3

VR,k

I 6.4.2 -a) 6.4.2

II -b) -a) 6.4.4

max. u 6.5.2

max. wS -c)

a) Determination of resistance of fastenings of sandwich panels on aluminium supporting struc-tures has to be based on tests.

b) Within the application range given in chapter 6.4.2, no further verification of the characteristicshear resistance of the supporting structure has to be done.

c) The value of transverse compression deformation is usually limited to wS,Ck = 1 mm.

The characteristic values of resistance depend on spacing, edge distance and ar-rangement of the fasteners and have to be checked against the test provisions orapplication range of calculation formulas.



4.3 Design of fastenings

Partial safety factors for resistance values apply in design. The design values ofresistance are calculated by dividing the characteristic values with the partial safe-ty factor gM:

M

IRkIRd

NN

g,

, =

Eq. (4.5)

M

IIRkIIRd

NN

g,

, =

Eq. (4.6)

M

IRkIRd

VV

g,

, =

Eq. (4.7)

M

IIRkIIRd

VV

g,

, =

Eq. (4.8)

fM

RkRd

uuu,

maxg

=º

Eq. (4.8)

serM

CkSCdSS

www

,

,,max

g=º

Eq. (4.8)

Usually, a partial safety factor of gM = 1.33 applies for ultimate limit state design offastenings of sandwich panels, but deviating values may be given in some approv-als or in some national specifications. EN 1995-1-1 gives gM = 1.3 for timber sup-porting structures, but since differences are negligible, gM = 1.33 is applied uni-formly for ultimate limit state design.For serviceability limit state and fatigue limit state, gM,ser = 1.00 and gM,f = 1.00 ap-ply. As partial factors are set to unity, the designation "max u" and "max wS" usual-ly apply.The following proofs have to be made:



0.1,

£IRd

Ed

NN

Eq. (4.9)

0.1,

£IIRd

Ed

NN

Eq. (4.10)

0.1,

£IRd

Ed

VV

Eq. (4.11)

0.1,

£IIRd

Ed

VV

Eq. (4.12)

0.1max

£u

u

Eq. (4.13)

0.1max

£S

S

ww

Eq. (4.14)

In case of repeated shear forces with load reversal (shear forces with changingdirection), interaction has to be checked if VEd ³ 0.25 VRd,I using

, ,

0.75 1.0Ed Ed

Rd I Rd I

N VN V

× + £

Eq. (4.15)

Deviating interaction approaches may be used if proven by tests. See also Kilian etal. (2015) for enhanced interaction approaches. Care should be taken in caseswere equivalent static forces are used to design for effects actually associated witha load reversal (e.g. wind loads or seismic loads in structures with sandwich pan-els serving as bracing). In these cases, interaction should be checked using Eq.(4.15).



In any case, for the supporting structure (component II) the interaction equation

0.1,,

£+IIRd

Ed

IIRd

Ed

VV

NN

Eq. (4.16)

applies. For timber supporting structures EN 1995-1-1 Eq. (8.28) leads

0.12

,

2

,

£÷÷ø

öççè

æ+÷

÷ø

öççè

æ

IIRd

Ed

IIRd

Ed

VV

NN

Eq. (4.17)

However, application of Eq. (4.16) is generally not covered by the ETAs of the fas-teners.


5 RESISTANCE DETERMINED BY TESTING


5.1 General

Performance and evaluation of tests is described in ECCS publication no. 127/CIBpublication no. 320 (2009), CUAP (2010) and prEN 14509-2 (2017). In case re-sistance values are based on tests, they are often published in approvals. Theseare either national approvals, European Technical Approvals or European Tech-nical Assessments. They are usually published on request of a fasteners manufac-turer, but sometimes also on request of a manufacturer of sandwich panels, takinginto account the effects of geometry and material properties of the panel on thepull-through resistance of the fastening, something which is particularly relevant forindirect fastenings. The latter also applies for resistance values based on tests ac-cording to prEN 14509-2 (2017). They are essential characteristics declared by themanufacturer of the sandwich panel with the resistance value specified in the CE-mark and Declaration of Performance (DoP).

5.2 Design based on an approval for fasteners

5.2.1 Sandwich panels on steel or aluminium supporting structuresDesign of fasteners for sandwich panels on steel or aluminium supporting struc-tures is based on tabulated values. Applicability of design tables depends on mate-rial properties (steel grade for example) of components I and II. Nominal sheetthicknesses are input values for determining the resistance values: Shear re-sistance is given depending on the nominal thickness tnom,II of the supporting struc-ture and nominal thickness tnom,F2 of the internal face. Tensile resistance is givendepending on the nominal thickness tnom,II of the supporting structure and nominalthickness tnom,F1 of the external face. Values for tensile resistance are not applica-ble for hidden fastenings, but pull-out resistance may be deduced from the tables(see chapter 5.3). In addition to division by a safety factor, no further calculationprocedures are necessary.Allowable head deflection is given depending on the nominal thickness tnom,II of thesupporting structure and distance DF between top of supporting structure and topof external face at point of fastening. Fig. 5.1 and 5.2 show examples of EuropeanTechnical Approvals for fasteners for fastening sandwich panels on steel support-ing structures.



Fig. 5.1: Example of a table from an ETA - steel supporting structure



Fig. 5.2: Example of a table from an ETA - steel supporting structure



5.2.2 Sandwich panels on timber supporting structuresDesign of fasteners for sandwich panels on timber supporting structures may bebased on tabulated values, but is often amended by design procedures given inEN 1995-1-1, see chapter 6 of this recommendation.In the latter case, input parameters such as withdrawal strength fax,k and character-istic yield moment of fastener My,Rk are given in the approval.Tables contain of evaluated design equations, providing resistance values for dif-ferent screw-in lengths for fixed materials and modification factors. Applicability ofdesign tables depends on material properties (steel grade for example) of compo-nent I and modification factors of at least the factor given. Tables issued for struc-tural timber according EN 14081 may also be used for glued laminated timber andglued solid timber according to EN 14080.Nominal sheet thicknesses and screw-in length are input values for determiningthe resistance values: Shear resistance is given depending on the screw-in lengthand nominal thickness tnom,F2 of the internal face. Tensile resistance is given de-pending on screw-in length and nominal thickness tnom,F1 of the external face. Careshould be taken as screw-in length is sometimes given as effective screw-in lengthleff or screw-in length including drill point lg = leff + lb. Applied modification factor kmod

is usually given. Beside division by a safety factor, no further calculation proce-dures are necessary.Allowable head deflection is given depending on distance DF between top of sup-porting structure and top of external face at point of fastening. Fig. 5.3 and 5.4show examples of European Technical Approvals for fasteners for fastening sand-wich panels on timber supporting structures.



Fig. 5.3: Example of a table from an ETA - timber supporting structure



Fig. 5.4: Example of a table from an ETA - timber supporting structure



5.3 Design based on an approval for sandwich panels or EN 14509-2

Fastenings of sandwich panels are not yet covered by current version of EN14509, therefore resistance values depending on geometry and material propertiesof the panels (for example pull-through resistance of hidden fastenings) cannot bespecified in the CE-mark or Declaration of Performance (DoP), but need to bespecified elsewhere. This is often done in a national approval. With publication ofEN 14509-2, situation will change and resistance values will be specified in theCE-mark and DoP. Nevertheless, in some cases, only a technical documentationpublished by the panel manufacturer exists. The manufacturer has to give infor-mation about the boundaries and parameters applied during the tests and to con-firm that the evaluation of the test corresponds to the state of the art. The designerhas to reconfirm themself that the technical documentation resembles the state ofthe art and that the parameters of the structure lay within the boundaries describedin the documentation. Especially it must be checked if the values provided arecharacteristic values or design values of resistance or even allowable values ac-cording to a deterministic safety concept.The designer may take the pull-through resistance provided by the approval for thesandwich panel (see Figs. 5.5. and 5.6 as examples). The pull-out resistance maybe taken from the approval of the fastener (see chapter 5.2) or be determined bycalculation (see chapter 6.2). In the first mentioned case, where tables give tensileresistance depending on both nominal thickness of the external face and nominalthickness of the supporting structure, the pull-out resistance may be estimated asthe tensile resistance assuming maximum thickness of the external face.The smaller value of both pull-through-resistance and pull-out resistance is thetensile resistance of the fastening.



Fig. 5.5: Example of an annex of a national approval for a sandwich panel



Fig. 5.6: Example of a CE-mark (preliminary draft)


6 RESISTANCE DETERMINED BY CALCULATION




6.1 Application range

Although the equations given in this chapter allow for calculation of characteristicvalues of resistance, they are also based on tests. These equations were derivedby evaluating large numbers of tests. As these tests cover only a limited applica-tion range, application of the equations is limited to this specific range, usually ex-pressed by material properties of the sandwich panel, the supporting structure orfastener and washer, but also spacing and edge distance. For applications outsidethe specified scope, design shall be based on tests unless otherwise specified inthe following.

6.2 Pull-through resistance

6.2.1 BackgroundFirst investigations on pull-through resistance of fastenings for sandwich panelswere done by Hassinen (2005), restricted to sandwich panels with flat or lightlyprofiled faces and a mineral wool core. The design approach given here for directfastening of sandwich panels with flat or lightly profiled faces was published byHassinen & Misiek (2009). This approach was amended for crest-fastening withoutsaddle washers of panels with profiled faces by Misiek & Ummenhofer (2012). Lat-est research by Ungermann & Lübke (2012) led to more sophisticated approachesfor panels with flat or lightly profiled faces, but generally confirmed the approachesgiven below.

6.2.2 Design procedures for sandwich panels with steel facesThe characteristic value of the pull-through resistance of fastenings of sandwichpanels with flat or lightly profiled faces can be calculated using

WFuFWCcCckFkCIRk dftdfEFFN ×××+×××=+= 1,12

,,, 65.021.2

Eq. (6.1)

withECc compression modulus of the corefCc compression strength of the coredW diameter of the washertF1 design core sheet thickness of the external facefu,F1 tensile strength of the external face



The application range of Eq. (6.1) is limited:- direct fastening;- external faces made of steel;- mineral wool, polystyrene, polyurethane or polyisocyanurate core material;- panel thickness dC ≥ 40 mm;- 2.0 N/mm² £ ECc £ 8.0 N/mm² compression modulus of the core. Values ECc

> 8.0 N/mm² should not be taken into account;- 0.1 N/mm² £ fCc £ 0.3 N/mm² compression strength of the core. Values fCc >

0.3 N/mm² should not be taken into account;- 0.40 mm £ tF1 £ 0.80 mm design core sheet thickness of the face (steel).

Values tF1 > 0.80 mm should not be taken into account;- 360 N/mm² £ fu,F1 £ 520 N/mm² tensile strength of the face (steel). Values

fu,F1 > 520 N/mm² should not be taken into account;- self-tapping screws and self-drilling screws made of steel or stainless steel;- diameter of the screws 5.5 mm £ d £ 8.0 mm;- diameter of the head ≥ 8.0 mm;- washers made of austenitic stainless steel- diameter of the washer dW ≥ 11 mm;- thickness of the metallic part the washer tw ≥ 1.0 mm, thickness of the

cured-on elastomer seal ≥ 2.0 mm- pull-through failure of the screw head through the washer itself as this could

be observed for dW ≥ 29 mm has to be excluded;

The simulated central support test according to EN 14509 uses the design re-sistance NR,k,I according to EN14509. Therefore the use of NR,k,I according to Eq.(6.1) might lead to a reduced wrinkling stress at the central support.

This approach does not cover reduction of resistance due to repeated loading as itcan be neglected for smaller diameters of washers. As a simplified approach, re-sistance should be reduced to 75% in cases where first summand gives more than20% of the total resistance calculated (i.e if FC,k > 0.25 FF,k).

For crest-fastening of panels with profiled faces, the equation

( )÷÷÷

ø

ö

ççç

è

æ×+××××+×××=

÷÷ø

öççè

æ×

×-

2

1

8

1,12

, 45.055.065.021.2 bd

WFuFWCcCcIRk

w

edftdfEN p

Eq. (6.2)



applies withb1 width of a rib, see Fig. 6.1and the application range as given with Eq. (6.1), but only polyurethane or polyiso-cyanurate core material with auto-adhesive bond.

Fig. 6.1: Definitions of geometry according to EN 14509

6.3 Pull-out resistance

6.3.1 BackgroundAs there is no difference in failure modes and resistance, design procedures forcalculation of pull-out resistance given in EN 1993-1-3 (2006) and EN 1999-1-4(2007) do also apply for fastenings of sandwich panels.Latest design procedure for supporting structures made of steel or aluminium wasdeveloped by Hettmann (2008). The procedure is related to the one used for met-ric screws and nuts, but taking into account the local deformation behaviour of thesupporting structure, usually also consisting of thin sheets. Compared to theaforementioned equations, this approach leads to both higher and more realisticresults, but requires much more effort.For supporting structures made of timber, EN 1995-1-1 applies. The design proce-dures given there require pull-out parameters determined by tests, but may be alsoestimated by design equations.

6.3.2 Design procedures for steel and aluminium supporting structuresThe characteristic value of pull-out resistance is given by

{ }( )SGMG

MGAsSGAsIIRk VR

FFN

,

,,,

,min80.0 ×=

Eq. (6.3)



withFAs,SG Load-bearing capacity of the thread of the screwFAs,MG Load-bearing capacity of the inside thread in the supporting structureR(VMG,SG) Reduction divisor for combined failure in both threads taking into ac-

count failure of both threads.The load-bearing capacity of the thread of the screw is calculated using Eq. (6.4).

( )P

tdddmmfF IIpdpdSGuSGsSGAs

paa ×××ú

û

ùêë

é÷øö

çèæ×-+×××=

2tan15.02.1 ,,,

Eq. (6.4)

withas,SG ratio of shear to tensile strength (0.70 for austenitic stainless steels and 0.61

for low-alloy carbon steels)fu,SG tensile strength of the material of the screw (930 N/mm² for austenitic stain-

less steels and 1190 N/mm² for low-alloy carbon steels)tII design core sheet thickness of the supporting structure.and dimensions d, dpd, P and angle a according to Fig. 6.2.

Fig. 6.2: Definitions and dimensions for calculation of pull-out resistance

For self-drilling screws

{ }1;max ddd dppd =

Eq. (6.5)

applies. The load-bearing capacity of the inside thread in the supporting structureis calculated using Eq. (6.6).



ïî

ïí

ì

××

×=

MGAs

bII

MGAs

MGAs

Fta

FF

,

,

,

*1.1

*1.1 for { }

{ }mmttmmttmm

mmt

II

II

II

90.4*;max90.4*;max60,0

60.0

>££

<

Eq. (6.6)

with

ïî

ïí

ì

×

×=

pd

pd

pd

dd

dt

1.1

9.0* for

mmdmmdmm

mmd

pd

pd

pd

554

4

>£<

£

Eq. (6.7)

( )

( )

ïïïïï

î

ïïïïï

í

ì

úúúúúúú

û

ù

êêêêêêê

ë

é

÷øö

çèæ ×--×+

÷øö

çèæ +-××-+

×-

×+×

×××=

EAEA

cII

c

EAIIII

IIuMGAs

PmmP

tP

mmP

P

ttP

dfF

jp

j

jppp

jp

jp

415.0

...2215.0

...4

2

260.0*

2

2

,,for { }mmtt

mmt

II

II

90.4*;max

60.0

³

£

Eq. (6.8)

( )( )b

IIMGAs

mmmmtF

a60.0

60.0*95.0 , =×=

Eq. (6.9)

the exponent

( )( )

÷øö

çèæ

÷÷ø

öççè

æ

=×=

=

mmt

mmtFttF

b IIMGAs

IIMGAs

60.0*ln

60.0*95.0**

ln,

,

Eq. (6.10)

( )P

dd pdEApaj ×÷

øö

çèæ×-=

2tan

Eq. (6.11)



Pmmc

pj 215.0 ×=

Eq. (6.12)

Combined failure in both threads is taken into account with

SGAs

MGAsSGMG F

FV

,

,, =

Eq. (6.13)

and

( )( )ïî

ïíì

×+×+=

-×

÷øö

çèæ -×

SGMG

SGMG

V

V

SGMG

eeVR

,

,

15.2

1195.1

,

3.013.01 for

11

,

,

>£

SGMG

SGMG

VV

Eq. (6.14)

EN 1993-1-3 gives an alternative equation for self-tapping screws in supportingstructures made of steel:

îíì

××××××

=IIuII

IIuIIIIRk ftd

ftdN

,

,, 65.0

45.0 if

PtPt

II

II

³<

Eq. (6.15)

The application range of Eq. (6.15) is limited:- self-tapping screws made of steel or stainless steel;- diameter of the screws 3.0 mm ≤ d ≤ 8.0 mm;- tII ≥ 0.9 mm- fu,II > 550 N/mm² should not be taken into account in design;

EN 1999-1-4 gives an alternative equation for self-tapping screws or self-drillingscrews in supporting structures made of steel or aluminium:

3,, 95.0 IIIIuIIRk tdfN ×××=

Eq. (6.16)



The application range of Eq. (6.16) is limited:- self-tapping screws and self-drilling screws made of steel or stainless steel;- diameter of the screws 6.25 mm ≤ d ≤ 6.5 mm;- tII > 6 mm and fu,II > 250 N/mm² for aluminium should not be taken into ac-

count in design;- tII > 5 mm and fu,II > 400 N/mm² for steel should not be taken into account in

design;- the diameter of the drilling hole should be in accordance with the recom-

mendations of table 6.1

Table 6.1: Pre-drilling diameter for self-tapping screws

tnom,II [mm] 0.75> 0.75≤ 1.5

> 1.5≤ 3.0

> 3.0≤ 5.0

> 5.0≤ 7.0 > 7.0

d0 [mm] 4.0 4.5 5.0 5.3 5.5 5.7

6.3.3 Design procedures for timber supporting structuresEN 1995-1-1 applies for fastenings of sandwich panels for timber supporting struc-tures. Corrigendum A1 published in 2010 shall be taken into account, because ma-jor issue of this corrigendum were axially loaded screw fasteners. The provisionspresented here are limited to fastening to timber (solid timber, sawn, planed or inpole form, glued laminated timber). For fastening to wood-based structural prod-ucts (e.g. LVL) or wood-based panels, see EN 1995-1-1.Load-bearing capacity is calculated according to EN 1995-1-1, Eq. (8.40a):

8,0

22,

, sincos2.1 ÷÷ø

öççè

æ×

+××××

=a

kefkaxefRkax

ldfnF

rr

aaEq. (6.17)

withnef effective number of fasteners according to EN 1995-1-1, 8.2.3, Eq. (8.17)fax,k characteristic withdrawal strength perpendicular to the direction of graind external thread diameter of the screw, usually the nominal diameterlef effective length, penetration length of the thread, lef = lg - lb; lef ≥ 5·dlg screw-in length - part of thread into component II including length of drill pointlb length of unthreaded part of the drill pointa angle between the force and the direction of grainrk characteristic densityra associated density related to fax,k, usually ra = 350 kg/m³ for timber of



strength grade C24 as reference density

EN 1995-1-1 requires lef ≥ 5·d which is often reduced to lef ≥ 4·d for fastenings ofsheeting profiles or sandwich panels. If this is done, this has to be supported bytest results: The characteristic withdrawal strength fax,k has to be determined withthis lower effective length. For spacings and edge distances see table 6.2

Table 6.2: Minimum spacings and edge distances [mm]spacings and edge distances

spacingsdistance toend grain

distance to edgeparallel to grain

direction of grain || ^ || ^

d [mm] a1 a2 a3 a4

4.8 34 24 48 19

5.5 39 28 55 22

6.0 42 30 60 24

6.3 44 32 63 25

6.5 46 33 65 26

8.0 56 40 80 32

Designations according to EN 1995-1-1, see also Figs. 6.4 to 6.7.

For fasteners with threads usually applied for fastening of sandwich panels to tim-ber supporting structures, the characteristic withdrawal strength perpendicular tothe direction of grain can be calculated with

26, 1070 kkaxf r××= -

Eq. (6.18)

withfax,k characteristic withdrawal strength perpendicular to the direction of grain in

N/mm²rk characteristic density in kg/m³

For most fastenings of sandwich panels, Eq. (6.17) can be simplified to



8,0

3

,,350 ÷

÷÷

ø

ö

ççç

è

æ×××=

mkgldfF k

efkaxRkaxr

Eq. (6.19)

for n = nef = 1.0. For the calculation of the characteristic load-bearing capacity, themodification factor for duration of load and moisture content (see EN 1995-1-1,table 3.1) has to be taken into account:

mod,, kFN RkaxIIRk ×=

Eq. (6.20)

withkmod modification factor for load duration class and moisture content described by

service class

Actions are assigned to one of the load-duration classes given in table 6.3. Exam-ples of load-duration assignment are given in table 6.3, too. Since climatic loads(snow, wind) vary between countries, the assignment of load-duration classes maybe specified in the National annex to EN 1995-1-1.

Table 6.3: Load duration class

Load duration classOrder of accumulated

duration of characteristicload

Examples of loading

permanent more than 10 years self-weightlong-term 6 months - 10 years storage, temperature

medium-term 1 week - 6 months imposed floor load, snowshort-term less than one week snow, wind

instantaneous wind, accidental load



Table 6.4: Service class

service classaverage moisture

contentEnvironmental

conditions Example

1 12%

temperature 20°Cand relative hu-

midity of 65% ex-ceeded for just afew weeks per

year

components andstructures in

heated buildings

2 20%

temperature 20°Cand relative hu-

midity of 85% ex-ceeded for just afew weeks per

year

covered opencomponents and

structures (excep-tion: areas withcondensation

water

3 > 20%

climate conditionsleading to highermoisture contents

than in serviceclass 2

components andstructuresexposed to

weather

For fastenings of sandwich panels supported by solid timber or glued laminatedtimber in service class 1 or 2 and dominating wind loads, kmod = 1.0 applies in mostcases. For fastenings of sandwich panels supported by solid timber or glued lami-nated timber in service class 1 or 2 and dominating temperature loads, kmod = 0.70applies in most cases. If a load combination consists of actions belonging to differ-ent load-duration classes a value of kmod should be chosen which corresponds tothe action with the shortest duration, see EN 1995-1-1. E.g. for a combination ofdead load and a short-term load, a value of kmod corresponding to the short-termload should be used.

6.4 Shear resistance

6.4.1 BackgroundAs the internal face of the sandwich panel is usually thinner than the supportingstructure, failure of the internal face dominates load-bearing capacity of the fas-tening. This is also expressed by the available design equations which base on theproperties of the internal face, only, but require minimum resistance of the support-ing structure. For steel supporting structures this minimum resistance is defined by



parameters of the application range. Up to now, no comparable application rangeis available for panels on aluminium supporting structures. For timber supportingstructures, an additional verification of the capacity of the supporting structure hasto be done.Equations for calculating the shear resistance of fastenings were developed withinthe framework of the EASIE project and published in the reports by Käpplein &Misiek (2011). A summary can be found in Käpplein & Ummenhofer (2011).

6.4.2 Design procedures for sandwich panels with steel facesThe characteristic shear resistance represented by the bearing strength of the in-ternal face can be estimated using

2,13

2, 2.4 FuFIRk fdtV ×××=

Eq. (6.21)

withtF2 design core sheet thickness of the internal face of the sandwich paneld1 internal thread diameter of the threaded part of the fastenerfu,F2 tensile strength of the internal face

The application range is limited:- direct or hidden fastening, no indirect fastening;- internal faces made of steel;- mineral wool, polystyrene, polyurethane or polyisocyanurate core material;- panel thickness dC ≥ 40 mm;- self-tapping screws and self-drilling screws made of steel or stainless steel;- diameter of the screws 5.5 mm ≥ d ≥ 8.0 mm;- 0.40 mm £ tF2 £ 1.00 mm design core sheet thickness of the internal face

(steel). Values tF2 > 1.0 mm should not be taken into account;- tII ≥ 1.46 mm core thickness of the supporting structure (steel or aluminium);- spacing and edge distances according to Fig. 6.3.



Fig. 6.3: Spacing and edge distances

Within the application range, no further verification of the characteristic shear re-sistance VRk,II of the supporting structure (component II) has to be done. For inter-action verification for the supporting structure, VRk,II might be conservatively esti-mated by evaluating Eq. (6.21) for tII = tF2 = 1.46 mm.

6.4.3 Design procedures for sandwich panels with aluminium facesUp to now, no design formulas are available for sandwich panels with aluminiumfaces. Determination of resistance of fastenings of sandwich with aluminium faceshas to be based on tests.

6.4.4 Additional design procedures for timber supporting structuresEN 1995-1-1 applies for fastenings of sandwich panels for timber supporting struc-tures. The provisions presented here are limited to fastening to timber (solid tim-ber, sawn, planed or in pole form, glued laminated timber). For fastening to wood-based structural products (e.g. LVL) or wood-based panels, see EN 1995-1-1.Load-bearing capacity is calculated according to EN 1995-1-1, Eq. (8.9):

ïî

ïíì

+××××

×××=

4215.1

4.0min ,

,,

1,

, RkaxefkhRky

efkh

RkV FdfM

dtfF

Eq. (6.22)

withfh,k characteristic embedment strength of timber membert1 is the smaller of the thickness of the timber side member or the penetration

depthdef effective diameter: 1.1-times the thread root diameter, for which the simplified



assumption of 0.7·d can be made. For screws with partially smooth shank di-ameter and a penetration depth > 4·d def is taken as the shank diameter

My,Rk characteristic yield moment of fastenerFax,k characteristic axial withdrawal capacity of the fastener acc. to Eq. (6.17) or

Eq. (6.19)

Eq. (6.22) applies for tF1 ≤ 0.5·d, neglecting the effect of clamping of the fastener inthe sandwich panel. Clamping of the fasteners and assuming a plastic hinge in thefastener as given by EN 1995-1-1, Eq. (8.10) should not be taken into account be-cause the thin faces do not prevent deformation by elongation of holes and do notallow evolution of a plastic hinge.Eq. (6.22) assumes fasteners perpendicular to the direction of grain. Nails in endgrain should not be considered capable of transmitting lateral forces. Spacing andedge distances according to Figs. 6.4 to 6.7 and table 6.5 apply.

Fig. 6.4: Spacing and edge distances

Fig. 6.5: Edge distances in the direction of force - loaded edge



Fig. 6.6: Edge distances in the direction of force - unloaded edge

Fig. 6.7: Edge distances perpendicular to the direction of force

a3,c

d

direction of force

direction of graina4,c

a4,c

d

direction of force

direction of grain



Table 6.5: Minimum spacings and edge distances [mm]spacings and edge distances

in direction of force perpendicular tothe direction of

forcespacings distance toloaded edge

distance tounloaded edge

direction of grain || ^ || ^ || ^ || ^

d [mm] a1 a2 a3,t a4,t a3,c a4,c a3,c a4,c

4.8 24 14 58 24 34 14 34 14

5.5 28 17 66 39 39 17 39 17

6.0 30 18 72 42 42 18 42 18

6.3 32 19 76 44 44 19 44 19

6.5 33 20 78 46 46 20 46 20

8.0 40 24 96 56 56 24 56 24

Based on the assumption of predrilled holes, including fastenings with self-drilling screws.Designations according to EN 1995-1-1, see also Figs. 6.4 to 6.7.See EN 1995-1-1 for detailed determination of spacings and edge distances or for applicationsnot covered here.

EN 1995-1-1 requires a minimum effective length of lef ≥ 5·d, but if confirmed bytests, a smaller value of lef ≥ 4·d may be used, see chapter 5 of this recommenda-tion.The characteristic embedment strength for fastenings with predrilled holes (includ-ing fastenings with self-drilling screws) is calculated with

( ) kefkh df r××-×= 01.01082.0,

Eq. (6.23)

withdef effective diameter: 1.1-times the thread root diameter, for which the simplified


rk characteristic density

For calculating the embedment strength, d can be used instead of def, causing nosignificant difference in value. If not available, the characteristic yield moment of afastener is calculated with



6.2,, 3.0 efSGuRky dfM ××=

Eq. (6.24)

withfu,SGk characteristic tensile strength, in N/mm². A value of fu,SG = 500 N/mm² should

be assumed using this equation.def effective diameter: 1.1-times the thread root diameter, for which the simplified


The summand Fax,k/4 describes the effects of catenary action and has to be limitedto

efkhRkyRkax dfM

F××××£ ,,

, 215.14

Eq. (6.25)

The increase in stressing of component I (pull-through resistance of the externalface of the sandwich panel) has to be taken into account. The characteristic valueof shear resistance of the timber supporting structure (component II) is

mod,, kFV RkVIIRk ×=

Eq. (6.26)


service class, see chapter 6.2.3.

For component I, an additional verification using Eq. (6.21) has to be done, takinginto account the resistance of the internal face. The smaller value applies.

When a force in a connection acts at an angle to the grain the possibility of splittingcaused by the tension force component VEd sina perpendicular to the grain shallbe taken into account. Splitting resistance shall be checked against the shear forc-es on either side of the connection using the splitting capacity



bb

bhmm

NFe

eRk

-××=

114

23,90

Eq. (6.27)

withh is the timber member heightbe is the loaded edge distance to the center of the most distant fastenerb is the timber member width (width of support)

The characteristic value of splitting resistance of the timber supporting structure(component II) is

mod,90,,90 kFV RkIIRk ×=

Eq. (6.28)


service class, see chapter 6.2.3.

6.5 Head deflection

6.5.1 BackgroundAllowable value of head deflection depends on material of the fastener, length ofcantilever (thickness of the panel) and rotational spring at point of clamping intothe supporting structure (thickness of the supporting structure). Calculation of headdeflection u(DT) is described in Annex A. As tests are comparatively time-consuming and expensive, but demanded head deflection is usually much lowerthan allowable value of head deflection determined in tests, simple and conserva-tive equations were developed in Misiek et al. (2011) and Misiek et al. (2013).

6.5.2 Design equations for steel, aluminium and timber supporting structuresThe design equations for austenitic stainless steel fasteners can be written as

ïî

ïíì

×

×=

F

II

F

DtDmmu

07.0

3.0maxmax

Eq. (6.29)



and for carbon steel fastener can be written as

220 51

0 023

F

II

F

D. mmtmax u

. D

ì ×ï= íï ×î

Eq. (6.30)

These equations were originally developed for steel supporting structures, but giveconservative but not uneconomical values for aluminium supporting structures. Fortimber supporting structures, the minimum value given with each equation is aconservative approximation.


7 EXECUTION AND MAINTENANCE


7.1 General

This chapter gives information about basic requirements on execution and mainte-nance. Additional information can be found in EN 1090-4 (2016), EN 1090-5(2016), IFBS (2014), RAGE (2014a) and RAGE (2014b).Fasteners according to European Standards, European Technical Assessments(ETA), European Technical Approvals (ETA) or national technical approvals shallbe used in fastening the sandwich panels to the supporting structure or in the con-nections between the adjacent sandwich panels.The type of fastener with designation of the relevant European Standard, ETA orapproval (which states the dimensions, materials and mechanical properties of thefasteners as well as characteristic values of the resistance of the connections)shall be specified.

7.2 Layout drawings

Layout drawings shall be prepared for the execution as a part of the executionspecification as defined in EN 1090-4 and EN 1090-5. With respect to fastening,the following details shall be included:

- fasteners with type designation and material- type and material of washer and/or saddle washer- arrangement and separation distances (spacings, end and edge distances)- predrill-diameter and pre-drilling depth for self-tapping screws, concrete

screws and spikes- minimum effective length for timber supporting structures- special assembly instructions depending on the type of fastening

7.3 Product and procedure testing

The performance of fasteners will depend on the site methodology that may bedetermined by procedure testing. Procedure tests may be used to demonstratethat the required connections can be performed under site conditions.

7.4 Installation personnel

Installation may only be undertaken by companies that possess the necessaryspecialist knowledge and experience and can demonstrate they employ sufficient



qualified personnel. The following aspects should be considered:a) ability to produce correct hole size for self-tapping screws and rivets;b) ability to correctly adjust power screwdrivers with the correct tightening

torque/depth location;c) ability to drive a self-drilling screw perpendicular to the connected surface

and set sealing washers to correct compression within the limits recom-mended by the washer manufacturer;

d) ability to form an adequate structural connection and to recognize an inade-quate one.

7.5 Installation

7.5.1 Alignment of sandwich panelsIt is important for the end result that the panels themselves are well aligned whenlifted on the final positions. This assures that installers easily find the correct fas-tening points. If the installers use the panel manufacturer’s recommended dimen-sions (e.g. distances between fasteners, edge distances) as defined in the layoutdrawings and the as-built spacings between the supporting elements, they are ableto define the center line of the supporting structure or the other target points. Thefixing problems may come from the fact that fasteners hit a wrong location in thesupporting structure, either too close to the welding or the edge. The correctalignment of the sandwich panel would help in many cases.

7.5.2 Fasteners and toolsThe type of fasteners, the diameters of sealing washers, the number of fastenersand the positions of fixing shall correspond to the requirements made in design.During installation, the provisions given in the approvals and the fabricator’s in-structions regarding suitable sheet thicknesses, materials, clamping thicknessesand tools to be used shall be fulfilled. Power tools for fixing screws shall possessan adjustable depth and/or torque control that shall be set in accordance with theequipment manufacturer's recommendations. If power screwdrivers are used, thedrilling and driving speeds (revolutions per minute) shall be in accordance with thefastener manufacturer's recommendations.

7.5.3 Position and inclination of fastenersSpecial care shall be taken to the positioning of the fasteners with respect to thesupporting structure. The position of the fastener in the upper flange of the sup-porting beam has tight tolerances for example. With I-shaped beams, the fastenersshall be arranged in a straight line or in an alternating fixing pattern positioned on



both sides of the beam’s flanges, depending on the requirements defined in thedesign. The pre-drill diameter of the self-tapping screws shall comply with the val-ue given in the technical approval.A minimum edge distance of ≥ 20 mm in direction of the span is required, if nolarger value is given by an approval or by the manufacturer.Fasteners shall be placed perpendicular to the surface of the panel to obtain asafe, water- and air-tight connection. This requirement might be a challenge incases in which the depth of the sandwich panels is large. Further information aboutthe mounting of regular sandwich panels can be found in the ECCS publication no.62 (1990), IFBS (2014), RAGE (2014a) and RAGE (2014b).The use of an additional guide in the screw gun to guarantee the perpendiculardirection of the screws in case of thick panels (> 100 mm) is recommended. Thelimiting factors for variances may be the tightness of the sealants of the washerunder static and dynamic loads, the performance of the drilling operation and thepositioning of the screw end in the correct place in the supporting structure.

7.5.4 Tightening of fastenersWhen attaching sandwich panels directly to supporting structure, the fastenershave to be positioned such that there is no gap at the point of contact betweencomponent I and component II.For a proper fixation of sandwich panels, the fasteners shall be tightened in a waythat the sealing washer has a slight deformation, required for a tight connection.This causes a light indentation of the external face of the sandwich panel which isunavoidable in practice. For flat and lightly profiled faces, the indentation should beless than 2 mm (Fig. 7.1). Larger deformations shall be avoided. The depth gauge,of a power screwdriver, shall be adjusted to compress the elastomeric washerwithin these limits.If screws are fastened in the crest of a sandwich panel with profiled face, care shallbe taken to avoid dents in the sheet at the penetration point.



Fig. 7.1: Tightening of the screws of sandwich panels to the supporting structure (figure: IFBS(2014))

7.6 MaintenanceThe building owner is advised to have roofs and façades serviced at regular inter-vals by qualified personnel with the necessary professional competence and expe-rience and sufficient knowledge in order to avoid damage.


REFERENCES

REFERENCES

Materials and Durability

Wieland H, (1988), Korrosionsprobleme in der Profilblech- und Flachdach-Befestigungstechnik(corrosion problems in roofing and siding), Befestigungstechnik Bau, SFS intec AG, Heerbrugg.

Misiek Th, Käpplein S, Ulbrich D, (2013), Selecting materials for fastening screws for metal mem-bers and sheeting, Steel Construction - design and research Vol. 6, pp. 39-46.

EN 1993-1-4, (2006). Eurocode 3: Design of steel structures - Part 1-4: General rules - Supplemen-tary rules for stainless steels. Published by CEN (Comité Européen de Normalisation), Brussels.

EN 1993-1-4/A1, (2015). Eurocode 3: Design of steel structures - Part 1-4: General rules - Supple-mentary rules for stainless steels. Published by CEN (Comité Européen de Normalisation), Brus-sels.

General design

EN 1990, (2002). Eurocode: Basis of structural design. Published by CEN (Comité Européen deNormalisation), Brussels.

EN 14509, (2013). Self-supporting double skin metal faced insulating panels - Factory made prod-ucts - Specifications. Published by CEN (Comité Européen de Normalisation), Brussels.

prEN 14509-2, (2017). Structural double skin metal faced insulating panels - Factory made prod-ucts - Specifications. Published by CEN (Comité Européen de Normalisation), Brussels.

EN 1993-1-3, (2006). Eurocode 3: Design of steel structures. Part 1-3: General rules, Supplemen-tary rules for cold-formed members and sheeting. Published by CEN (Comité Européen de Norma-lisation), Brussels.

EN 1999-1-4, (2007). Eurocode 9: Design of aluminium structures. Part 1-4: Cold-formed structuralsheeting. Published by CEN (Comité Européen de Normalisation), Brussels.

ECCS TC7, (2008), The Testing of Connections with Mechanical Fasteners in Steel Sheeting andSections, ECCS publication no. 124, Brussels.

ECCS TC7 TWG7.9 and CIB W056, (2009), Preliminary European Recommendations for testingand design of fastenings for sandwich panels, CIB publication 320 / ECCS publication no. 127,Rotterdam/Brussels.

ECCS TC7 TWG7.9 and CIB W056, (2015), European Recommendations for the Determination ofLoads and Actions on Sandwich Panels. ECCS publication no. 136/CIB publication no. 401, Brus-sels/Rotterdam.


REFERENCES

ECCS TC7 TWG7.9 and CIB W056, (under preparation), European Recommendations for the De-sign of Sandwich Panels with Point or Line Loads. ECCS publication/CIB publication, Brus-sels/Rotterdam.

EOTA, (2010), Fastening Screws for Sandwich Panels. CUAP 06.02/12, Common Understanding ofAssessment Procedure for European Technical Approval according to Article 9.2 of the Construc-tion Products Directive, Brussels.

Hassinen P, (2005), Resistance of fastenings of sandwich panels, Sandwich Structures 7: Advanc-ing with Sandwich Structures and Materials 2005 – Proceedings of the 7th International Conferenceon Sandwich Structures, pp. 471-476.

Hassinen P, Misiek Th, (2009), Fixings of sandwich panels in building applications, Nordic SteelConstruction Conference 2009 – Proceedings, pp. 263-271.

Misiek Th, Käpplein S, Hettmann R, Saal H, Ummenhofer Th, (2011), Rechnerische Ermittlung derTragfähigkeit der Befestigung von Sandwichelementen (computation of loadbearing capacity offixings of sandwich panels), Bauingenieur Vol. 86, pp. 418–424.

Misiek Th, (2010), Connections of Sandwich Panels / Spojevi sandwich panela, Presentation heldat the EASIE Workshop in Zagreb.

Kilian K, Lange J, Naujoks B, (2015), Verbindungen von Sandwichelementen unter kombinierterLängs- und Querkraftbeanspruchung, Stahlbau Vol. 84, pp. 866-874.

Structural analysis

Stamm, K, Witte, H, (1974), Sandwichkonstruktionen - Berechnung, Fertigung, Ausführung. Sprin-ger-Verlag, Wien, New York.

Berner K, (1998), Praxisgerechte Nachweise zur Tragfähigkeit und Gebrauchstauglichkeit vonSandwichelementen (Practical checks at ultimate limit state and serviceability limit state of sand-wich panels). Stahlbau Vol. 84, pp. 910-925.

Davies J M et al., (2001), Lightweight Sandwich Construction. Blackwell Science, Oxford.

SNPPA (2007), Formulaire de Résistance des Matériaux - Poutres avec prise en compte des dé-formations dues à la flexion et á l'effort tranchant, Tomes 1 à 5. SNPPA Syndicat national du Profi-lage des Produits Plats en Acier, Paris.

Naujoks B, Misiek Th, (2015), Praxisgerechte Nachweise zur Tragfähigkeit und Gebrauchstauglich-keit von Sandwichelementen mittels Fachwerkmodellen (Practical checks at ultimate limit state andserviceability limit state of sandwich panels using truss systems.). Stahlbau Vol. 84, pp. 890-907.

EN 14509, (2013). Self-supporting double skin metal faced insulating panels - Factory made prod-ucts - Specifications. Published by CEN (Comité Européen de Normalisation), Brussels.


REFERENCES

Pull-out resistance

Hettmann R, (2008), Statische Auszugstragfähigkeit gewindeformender Schrauben in Metall-konstruktionen, Berichte der Versuchsanstalt für Stahl, Holz und Steine der Universität Fridericianain Karlsruhe, 5. Folge Heft 16, Karlsruhe.

Pull-through resistance

Saal, H, Misiek, Th, (2008), Durchknöpftragfähigkeit der Befestigungsmittel von Sandwichelemen-ten bei direkter Befestigung (Pull-through resistance of fasteners of sandwich panels with directfixing). Bauforschung T 3160, Fraunhofer-Informationszentrum Raum und Bau IRB, Stuttgart.

Misiek Th, Saal H, Kathage K, (2008), Durchknöpftragfähigkeit der Befestigungsmittel bei Sandwi-chelementen mit direkter Befestigung, Stahlbau Vol. 77, pp. 352-359.

Misiek Th, Käpplein S, Kathage K, (2010), Pull-through resistance of tensile-loaded screw-fastenings of thin-walled sheeting and sandwich panels, In: Proceedings of SDSS’Rio 2010 Interna-tional Colloquium Stability and Ductility of Steel Structures, pp. 1009-1016.

Misiek Th, Ummenhofer Th, (2011), Crest-fixing of profiled sandwich panels without saddle wash-ers, In: Advances in Steel and Aluminum Structures, Research Publishing Services, pp. 515-521.

Misiek Th, Käpplein S, (2011), Pull-through resistance of tensile-loaded screw-fastenings of thin-walled sheeting and sandwich panels. In: Proceedings of the 6th international Conference on Thinwalled structures – Recent research advances and trends, ECCS, Brussels, pp. 521-528.

Ungermann D, Lübke S, (2012), Bemessungsmodell zur Durchknöpftragfähigkeit von Sandwiche-lementen bei direkter Verankerung (Design model for pull-through resistance of direct fastenings insandwich panels), Stahlbau Vol. 81, pp. 906-911.

Shear resistance

Käpplein S, Misiek Th, (2011), Tests on the in plane-shear resistance of sandwich panels - Connec-tions of sandwich panels. EASIE - Ensuring advancement in Sandwich Construction through Inno-vation and Exploitation; D3.2 - part 2,http://digbib.ubka.uni-karlsruhe.de/volltexte/documents/1770941.

Käpplein S, Misiek Th, (2011), Connections of sandwich panels - Stiffness and load bearing capaci-ty of shear loaded fastenings of sandwich panels. EASIE - Ensuring advancement in SandwichConstruction through Innovation and Exploitation; D3.3 - part 3,http://digbib.ubka.uni-karlsruhe.de/volltexte/documents/1770559.

Käpplein S, Ummenhofer Th, (2011), Querkraftbeanspruchte Verbindungen von Sandwichelemen-ten (Shear loaded fastenings of sandwich panels). Stahlbau Vol. 80, pp. 619-626.


REFERENCES

Execution and maintenance

ECCS TC7 TWG 7.4, (1990), Preliminary European Recommendations for Sandwich Panels – PartII Good Practice. ECCS publication no. 62, Brussels.

EN 1090-4, (2018). Execution of steel structures and aluminium structures – Part 4: Technical re-quirements for cold-formed structural steel elements and cold-formed structures for roof, ceiling,floor and wall applications. Published by CEN (Comité Européen de Normalisation), Brussels.

EN 1090-5, (2017). Execution of steel structures and aluminium structures – Part 5: Technical re-quirements for cold-formed structural steel elements and cold-formed structures for roof, ceiling,floor and wall applications. Published by CEN (Comité Européen de Normalisation), Brussels.

IFBS General Rules, (2014), General rules for the use of profiled metal sheeting - IFBS - TechnicalRules for Lightweight Metal Construction. IFBS International Association for Metal Building Enve-lopes, Krefeld.

IFBS Installation, (2014), Guideline for the planning and installation of roof, wall and deck construc-tions made from profiled metal sheeting - IFBS - Technical Rules for Lightweight Metal Construc-tion. IFBS International Association for Metal Building Envelopes, Krefeld.

RAGE, (2014a), Règles de l’art grenelle environnement 2012: Recommandations professionnelles– Bardages en panneaux sandwich a deux parements en acier et à âme Polyuréthane – Concep-tion et mis en œuvre. AQC Agence Qualité Construction, Paris.

RAGE, (2014b), Règles de l’art grenelle environnement 2012: Recommandations professionnelles– Couvertures en panneaux sandwich a deux parements en acier et à âme Polyuréthane – Con-ception et mis en œuvre. AQC Agence Qualité Construction, Paris.


REFERENCES


ANNEX

ANNEXES


ANNEX A: HEAD DEFLECTION


A.1 Mechanisms which cause head deflections

Both shear deformation (Fig. A.1) and bending rotation (Fig. A.2) at supports re-sults in a relative displacement of both faces, related to a deflection of the head ofthe fastener relative to the point of fixation at the supporting structure.

Fig. A.1: Shear deformation at support

Fig. A.2: Bending rotation at support

The shear strain g due to elastic shear deformation in the core is

gt

=GC

Eq. (A.1)

The bending rotation at the support is

g 1 =dwdx

Eq. (A.2)

The displacement u of the head of the fasteners can be calculated on the basis ofthe superposition of displacements u(g) and u(g1) as shown in Fig. A.3.



Fig. A.3: Displacements at the end of sandwich panel

( ) ( ) eDuuu F ×-×=-= gggg 11

Eq. (A.3)

with distance DF between top of supporting structure and top of external face atpoint of fastening.

The calculated deflection u shall be less than the maximum allowable value ofhead deflection max u as determined in chapter 6.5.

Analytical calculation methods to determine g and g1 for different mechanical sys-tems and loading conditions are given in the following chapters. For an approxi-mate calculation for single or multi-span panels with flat or profiled faces see chap-ter A.4. See Naujoks & Misiek (2015) for calculation of head deflection using trusssystems.

e

D FD



A.2 Analytical calculation procedures for single span panels

A.2.1 General parametersThe parameters and symbols which are used in calculating head deflection u com-ply with EN 14509, but are given here for easier use.

S shear stiffness of the coreB overall width of the panelL spane distance between centroids of facesdC depth of coreBF1, BF2 bending stiffness of the profiled external and internal faceBS bending stiffness of the sandwichaF1, aF2 coefficients of thermal expansion of faces 1 and 2

CC

CC GBdeGAS ××=×=

2

Eq. (A.4)

S

FF

S

D

BBB

BB 21 +

==a

Eq. (A.5)

2222 LGeBdB

LGAB

LSB

C

CS

CC

SS

××××

=××

=×

=b

Eq. (A.6)

baal

×+

=1

Eq. (A.7)



A.2.2 Sandwich panels with flat or lightly profiled faces

Table A|1: Simply supported panel with uniformly distributed load q0

20 LqV ×

= Eq. (A.8a)

SV

=g Eq. (A.8b)

SLq

BLq

S ××

+××

=2240

30

1g Eq. (A.8c)

Table A|2: Simply supported panel with a line load parallel to the supports

La

=e Eq. (A.9a)

( )e-×=-

×= 1FL

aLFVA Eq. (A.9b)

SVA

A =g Eq. (A.9c)

eeeg-

×=×

==1S

VS

FS

V ABB Eq. (A.9d)

[ ] ( )eeeeg -×++×-××××

= 1326

322

1, SF

BLF

SA Eq. (A.9e)

[ ] eeeg ×--×××

=SF

BLF

SB

32

1, 6Eq. (A.9f)



Table A|3: Simply supported panel with a temperature difference between the faces

g = 0 Eq. (A.10a)

[ ]e

LTT FF

×××-×

=2

11221

aag Eq. (A.10b)

A.2.3 Sandwich panels with profiled faces

Table A|4: Simply supported panel with uniformly distributed load q0

( ) úûù

êëé ×-×

+××

=2

tanh1213

0 ll

bgDS BB

LqEq. (A.11a)

( ) úûù

êëé ×

×-

××+×

+×

=2

tanh12

1241

32

30

1l

lalag

DS BBLq

Eq. (A.11b)



Table A|5: Simply supported panel with a line load parallel to the supports

La

=e Eq. (A.12a)

( )( )( )

úûù

êëé -×

--×+

××=

lelebg

sinh1sinh1

2

DSA BB

LFEq. (A.12b)

( )( )

úûù

êëé ×

+-×+

××=

lelebg

sinhsinh2

DSB BB

LFEq. (A.12c)

( ) [ ] ( )( )úû

ùêë

éúûù

êëé -×

--××

++×-×××+×

=l

elela

eeegsinh

1sinh113261

232

2

1,DS

A BBLF

Eq. (A.12d)

( ) [ ] ( )úû

ùêë

éúûù

êëé ×+-×

×+-××

+×=

lele

laeeg

sinhsinh1

61

23

2

1,DS

B BBLF

Eq. (A.12e)

Table A|6: Simply supported panel with a temperature difference between the faces

eTT FF 1122 ×-×

=aaq Eq. (A.13a)

2tanh l

lqg ×

×-=

LEq. (A.13b)

úûù

êëé ×-×

+×

=2

tanh121

11l

laqg L

Eq. (A.13c)

A.3 Analytical calculation procedures for multi-span panels

Head deflection for multi-span panels is determined by the superposition of thesimply supported system and the statically indeterminate forces as shown in Fig.



A.4 below (method of consistent deformation). An example can be found in AnnexC.

Fig. A.4: Method of consistent deformation for multi-span panels

A.4 Approximate calculation for single or multi-span panels with flat or pro-filed faces

For most applications, calculation of head deflection using approximate calculationprocedures is sufficient and leading to conservative results.

( ) ( )DS BBeLqqu

+×××

=24

30

0

Eq. (A.14)

( )2

eLTu ××=

qD

Eq. (A.15)

The limits of application of the above formulae are given by



L L L L1 2 3= = = =L

Eq. (A.16)

5.2>×SB

SL

Eq. (A.17)

see also Fig. A.5.

Fig. A.5: Application limits for approximate calculations


ANNEX B: TRANSVERSE COMPRESSION DEFORMATION


B.1 Calculation of deformation

The verifications shall be done using the formula

ïïî

ïïí

ì

×

÷÷ø

öççè

æ ××+×

××

=

SCc

Ed

S

kS

kCc

Ed

S

Le

EF

LeknL

knEF

wln1

if00.0

00.0

=

¹

k

k

Eq. (B. 1)

withFEd support reaction forceECc compression modulus of the coreLS width of the supportk distribution parameter according to EN 14509nk distribution factor, see figure B.1

Fig. B.1: Load distribution

The value of transverse compression deformation is usually limited to 1 mm. SeeRAGE (2014a) for further requirements and additional verifications.

B.2 Detailing requirements

To ensure tightness, screws with an additional thread under the head and washerswith dw ³ 19 mm and thickness of the cured-on elastomer seal ≥ 3.0 mm shall beused.


ANNEX C: DESIGN EXAMPLES


C.1 Background information

Both the following examples are based on the examples given in Berner (1998),Davies et al. (2001) and Naujoks & Misiek (2015). These examples are virtuallyidentical, with the exception of some small differences in loads. Compared to theaforementioned references, additional actions and loads are covered here.

C2 Wall panel

C.2.1 SystemWall panel spanning vertical, lying over two spans with L = 4000 mm. The panelhas lightly profiled faces and a nominal thickness of 60 mm.

Fig. C.1: Mechanical system

External face is made from structural steel S320GD+Z275 (fu,F1 = 390 N/mm²) ac-cording to EN 10346, nominal thickness is tnom,F1 = 0.60 mm with special toleranceaccording to EN 10143. Internal face is made from structural steel S320GD+Z275(fu,F2 = 390 N/mm²) according to EN 10346, nominal thickness is tnom,F2 = 0.50 mmwith special tolerance according to EN 10143.The core material is polyurethane foam with shear modulus GC = 3.1 N/mm².The panel will by fastened by hidden fastenings, using a load spreader plateplaced in the longitudinal joints between the panels. There is one load spreaderplate per panel of 1 m width, allowing fastening with up to three fasteners. In this



case two self-drilling screws 6.3 x L per load spreader plate are used at base andintermediate supports (supports No. 1 and No. 2) and one self-drilling screw 6.3 xL is used at top support (support No. 3). Both load spreader plates and fastenersare made of stainless steel.Supporting structure is a cold-formed C-section made from structural steelS390GD+Z275 (fu,II = 420 N/mm²) according to EN 10346, nominal thickness istnom,II = 2.00 mm with normal tolerance according to EN 10143. Shear forces fromself-weight loading are transferred only by the base support (support No. 3), seeFig. C.1.

C.2.2 Actions and loads

Self-weight3

A value of

²107.0

mkNgk =

is assumed throughout this example.

Wind suctionThe value

²25.0

²50.050.010, m

kNmkNqcw ppee -=×-=×=

as given in the aforementioned references is based on pressure coefficient cp,10

which applies for the design of the sandwich panel. For design of fastenings, cpe iscalculated for each support, with size of the loaded area (see EN 1991-1-4, chap-ter 7.2.1) simply defined from mid of span to mid of span.End supports (supports No. 1 and 3):

( ) ( ) 64.02log5.07.07.0log2

101010,1,1, -=×+---=×--=mmAcccc pepepepe

²32.0

²50.064.010, m


Intermediate support (support No. 2)

( ) ( ) 58.04log5.07.07.0log2


²29.0

²50.058.010, m


3 Load not given in original examples



Fig. C.2: Wind loads

TemperatureFor assumed colour group 2, the following values T1/T2 and DT apply for design:Winter temperature -20°C/+20°C DT = 40KSummer temperature +65°C/+25°C DT = -40KDepending on national regulations, higher values for external temperature T1 applyfor ultimate limit state design. For fatigue limit state (head deflection), a tempera-ture difference of DT = T2 - T1 = -70 K applies for design.

C.2.3 Characteristic values of support reactionsAll shear forces are transferred via the base support No. 1.

mkNm

mkNLgG kk 854.042

²107.02 =××=××=

Transverse support reactions are given in the following table. Support reactions forwind loads were determined by software. For detailed information on calculation ofsupport reactions under temperature loading see references.

Table C.1: Characteristic values of support reactions [kN/m]Support Wk Tk,Summer Tk,Winter

1 -0.505 0.483 -0.4832 -1.442 -0.966 0.9663 -0.505 0.483 -0.483

2000

m

m40

00 m

m20

00

mmwe = -0.32 kN

m²

we = -0.29 kNm²

we = -0.32 kNm²



C.2.4 Design values of support reactionsFor shear force

mkN

mkNGV kFEd 15.1854.035.11, =×=×= g

applies. Both the combinations

kTFkFEd TWN ××+×= 0yggand

kWFkFEd WTN ××+×= 0yggneed to be checked for maximum tensile forces at all three supports.

Fig. C.3: Support reactions

In this case, first combination leads to higher tensile forces:

²19.1483.06.05.1505.05.1,01, m

kNmkN

mkNTWN SummerkTFkFEd -=-××+-×=××+×= ygg

mkN

mkN

mkNTWN erWkTFkFEd 03.3966.06.05.1442.15.1int,02, -=-××+-×=××+×= ygg

²19.1483.06.05.1505.05.1,03, m

kNmkN

mkNTWN SummerkTFkFEd -=-××+-×=××+×= ygg

Because of symmetry both of mechanical system and loads, NEd,1 = NEd,3.

NEd,1

NEd,2

NEd,3

VEd,1



C.2.5 Head deflectionAnalytical calculation of head deflection for multi-span panels is based on methodof consistent deformations. In a first step, head deflection at end supports is calcu-lated for the single span panel with Leqv = 2 L = 800 cm and a temperature differ-ence of DT = T2 - T1 = -70 K.

( )cmcm

KK

eT

eTT

eTT TTFTFT 11043.1

866.5

701102.14

5

1211,22, -

-

×-=-××

=×

=-×

=×-×

=Daaaa

q

Shear strain due to elastic shear deformation in the core is0=Tg


2

4

1 1073.52

80011043.1

2-

-

×-=××-

=×

=cm

cmLeqvT

qg

In a second step, head deflection caused by the force F is calculated. The force Fis defined by the corresponding deflection which is equal to the one caused by thetemperature difference:

( )cm

cmcmL

w eqvT 5.11

8

80011043.1

8

242

-=××-

=×

=

-q

Hence the force F will eliminate the deformation at mid of span of the equivalentsingle span panel. For the deflection under a line load F

úúû

ù

êêë

é+

××

×=

SBLLF

wS

eqveqvF

1124

2

applies and therefore

( )( )

mkN

mkN

mkNcm

cmcm

cm

SBL

L

wwwF

S

eqveqv

TTF 69.1

8.181

1

187957912

800800

5.1141

12

4

2

2

2 =

úúúú

û

ù

êêêê

ë

é

+×

×

×=

úúû

ù

êêë

é+

××

×==

The corresponding values of shear strain due to elastic shear deformation andbending rotation at the support are

31065.48.1812

69.1

2-×=

×=

×=

mkN

mkN

SF

Fg

and



( ) 22

22

1 1006.48.1812

1

187957916

80069,12

116

-×=

úúúú

û

ù

êêêê

ë

é

×+

××=

úúû

ù

êêë

é

×+

××=

mkN

mkNcm

cmmkN

SBL

FS

eqvFg

The angles g1 resulting from shear deformation of the core at end support and gresulting from bending rotation have to be subtracted from each other. Head de-flection is finally calculated

( ) ( )( ) ( ) cmcmcm

eeeDu FTFTF

127.0866.51065.400.61006.41073.5 322111

-=××+-××+×-=

×+-×+=×-×=---

gggggg

with DF » d for wall panels with flat or lightly profiled faces.

C.2.6 Resistance and VerificationsPull-through resistanceThere is one load spreader plate per panel of 1 m width. The characteristic valuesof pull-through resistance were taken from the national approval of the sandwichpanel, see Fig. C.4.



Fig. C.4: Annex of the national approval with pull-through resistance



Design values of pull-through resistance for each support

kNkNNN

M

IRkIRd 60.1

33.113.21,,

1,, ===g

kNkNNN

M

IRkIRd 11.3

33.114.42,,

2,, ===g

kNkNNN

M

IRkIRd 60.1

33.113.23,,

3,, ===g

Verifications

0.174.060.119,1

1,,

1, <==kNkN

NN

IRd

Ed

0.197.011.303.3

,

2, <==kNkN

NN

IRd

Ed

0.174.060.119.1

3,,

3, <==kNkN

NN

IRd

Ed

Pull-out resistanceThere is one load spreader plate per panel of 1 m width, with two fasteners at baseand intermediate support, one fastener at top support.Supporting structure is a cold-formed C-section made from structural steelS390GD+Z275 (fu,II = 420 N/mm²) according to EN 10346, nominal thickness istnom,II = 2,00 mm with normal tolerance according to EN 10143. In case of normaltolerances, tolerances have to be considered in calculation of design core sheetthickness.Design core sheet thickness of the supporting structure:

mmmmmmmmtttt tolzincIInomII 88.116.05.004.000.25.0, =×--=×--=

Dimensions of self-drilling screws 6.3 x L made of stainless steel:d = 6.3 mmd1 = 4.8 mmddp = 5.5 mmP = 1.8 mma = 60°

{ } { } mmmmmmddd dppd 5.58.4;5.5max;max 1 ===



Load-bearing capacity of the thread of the screw

( )

( )

Nmm

mmmmmmmmmmmm

N

PtdddmmfF II

pdpdSGuSGsSGAs

86268.1

88.15,52

60tan5.53.615.093070.02.1

2tan15.02.1

2

,,,

=

×××ú

û

ùêë

é÷øö

çèæ °

×-+×××=

×××úû

ùêë

é÷øö

çèæ×-+×××=

p

paa

Load-bearing capacity of the inside thread in the supporting structurefor dpd > 5 mm

mmmmdt pd 05.65.51.11.1* =×=×=

( ) ( ) 806.08.12

60tan5.53.62

tan =×÷øö

çèæ °

×-=×÷øö

çèæ×-=

mmmmmm

Pdd pdEA

ppaj

524.08.1215.0215.0 =×=×=mm

mmP

mmcppj

F*As,MG for tII = 0.60 mm

( )

N

mmmmmm

mmmmN

ttP

dfF EAIIIIIIuMGAs

820

806.060.060.08.12

3.639060.0

260.0*

22

2,,

=

úûù

êëé ×+××××=

úûù

êëé ×+××××=

p

jp

F*As,MG for tII = t* = 6.05 mm

( )

( )

( )

( )

N

mmmmmm

mmmm

mmmm

mm

mmmm

N

PmmP

tP

mmP

P

dfF

EAEA

cII

c

IIuMGAs

23094

806.048,115.08.1806.0

...524.0205.68.1215.08.1

...48.1524.02

23.639060.0

415.0

...2215.0

...4

2

260.0*

2

2

2

,,

=

úúúúúúú

û

ù

êêêêêêê

ë

é

÷øö

çèæ ×--×+

÷øö

çèæ +-××-+

-

×××=

úúúúúúú

û

ù

êêêêêêê

ë

é

÷øö

çèæ ×--×+

÷øö

çèæ +-××-+

-

×××=

p

ppp

p

jp

j

jppp

jp

( )( )

47.1

60.005.6ln

82095.023094ln

60.0*ln

60.0*95.0**

ln,

,

=÷øö

çèæ

÷øö

çèæ

×=÷øö

çèæ

÷÷ø

öççè

æ

=×=

=

mmmm

NN

mmt

mmtFttF

b IIMGAs

IIMGAs



( )( ) ( )

Nmm

Nmm

mmtFa b

IIMGAs 164760.0

82095.060.0

60.0*95.047.1

, =×

==×

=

( ) NmmNtaF bIIMGAs 415888,11647 47.1

, =×=×=

Reduction divisor for combined failure in both threads

482.086264158

,

,, ===

NN

FF

VSGAs

MGAsSGMG

( ) ( ) 037.13.013.01 482.01195.1

1195,1

,, =×+=×+=

-×÷øö

çèæ -×

eeVR SGMGVSGMG

Characteristic value of pull-out resistance{ }

( ){ } NNN

VRFF

NSGMG

MGAsSGAsIIkR 3208

037.14158;8626min80.0

;min80.0

,

,,,, =×=×=

For comparison, characteristic value of pull-out resistance is additionally calculatedaccording to EN 1993-1-3 and EN 1999-1-4, respectively:with tII ³ P

Nmm

NmmmmftdN IIuIIIIRk 300239088.13.665.065.0 2,, =×××=×××=

( ) Nmmmmmm

NtdfN IIIIuIIRk 239788.13.639095.095.0 32

3,, =×××=×××=

Design value of pull-out resistance

kNNNN

M

IIRkIIRd 41,2

33.13208,

, ===g

Verifications, with two screws per a load spreader plate at base and intermediatesupport

0.149.041.219,1

,

1, <==kNkN

NN

IIRd

Ed

0.163.041.22

03.3

,

2, <=×

=å kN

kNN

N

IIRd

Ed

0.125.041.22

19,1

,

3, <=×

=å kN

kNN

N

IIRd

Ed

Shear resistanceAt support No. 1 there are two screws per load spreader plate and panel of 1 mwidth.Dimensions of self-drilling screws 6.3 x L made of stainless steel:d = 6.3 mmd1 = 4.8 mm



Internal face is made from structural steel S320GD+Z275 (fu,F2 = 390 N/mm²) ac-cording to EN 10346, nominal thickness is tnom,F2 = 0.50 mm with special toleranceaccording to EN 10143.Design core sheet thickness of the internal face:

mmmmmmttt zincFnomF 46.004.050.02,2 =-=-=

Characteristic value of shear resistance:

( ) Nmm

NmmmmfdtV FuFIRk 11203908.446.02.42.4 23

2,13

2, =×××=×××=

Design value of shear resistance

kNNVVV

M

IRkIRdRd 84.0

33.11120,

, ====g

Verification, with two screws at support No. 1

0.168.084.02

15,11, <=×

=å kN

kNV

V

Rd

Ed

In this example, use of a support angle at base point to transfer self-weight loadingwould allow reduction of number of fasteners to one per meter, loaded only by ten-sile forces.

InteractionInteraction verification has to be made for supporting structure only. While forNRd,II, a specific value was derived in this example, there is no equation for explicit-ly calculating the shear resistance VRd,II. VRd,II is conservatively estimated.Characteristic value of shear resistance:

( ) Nmm

NmmmmfdtV FuIIIIRk 68174208.446.12.42.4 23

2,13

, =×××=×××»


kNNVV

M

IIRkIIRd 13.5

33.16817,

, ===g

Verification, with three fasteners at support No. 1

0.136.011.025.013.52

15.141.22

19.1

,

1,

,

1, <=+=×

+×

=+kN

kNkN

kNVV

NN

IIRd

Ed

IIRd

Ed



Allowable head deflection

mmmm

mmmmtdmmu

II

C 57.988.1

603.03.0max =×=×=

Verification

0.113.0957.0127.0

max<==

cmcm

uu

C.3 Roof panel

C.3.1 SystemRoof panel, lying over two spans with L = 3300 mm, with a slope of 10°. The panelhas a profiled external face with pitch of profile p = 333 mm and width of the crestb1 = 35 mm. The internal face is lightly profiled. The nominal thickness is 60 mm,the thickness at crest is D = 98 mm.


External face is made from structural steel S320GD+Z275 (fu,F1 = 390 N/mm²) ac-cording to EN 10346, nominal thickness is tnom,F1 = 0.60 mm with special toleranceaccording to EN 10143. Internal face is made from structural steel S320GD+Z275(fu,F2 = 390 N/mm²) according to EN 10346, nominal thickness is tnom,F2 = 0.50 mmwith special tolerance according to EN 10143.The core material is polyurethane foam with shear modulus GC = 3.02 N/mm²,compression modulus 3.5 N/mm² (not given in original examples) and compressionstrength 0.11 N/mm².The panel will by fastened by crest fastenings, using washers dw = 19 mm withcured-on elastomer seals (no saddle washers). At base support (support No. 1),there are three fasteners per panel of 1 m width and per support, with each crestfastened. At intermediate and top support (supports No. 2 and No. 3), there aretwo fasteners per panel of 1 m width and per support, with two crests fastened andone crest unfastened per panel. Self-tapping screws 6.3 x L made of stainlesssteel are used.Supporting structure is a hot-rolled section made from structural steel S235JR (fu,II

= 360 N/mm²) according to EN 10025-2, nominal thickness is tnom,II = 5.00 mm.



Shear forces from self-weight loading are transferred only by support No. 1, seeFig. C.5.Chapter C.4 deals with the identical system and sandwich panel, but fastened on asupporting structure made of timber using a different type of fastener.

C.3.2 Actions and loads

Self-weightA value of

²166.0

mkNgk =

is assumed throughout this example. It is split into two components, one actingperpendicular to the panel and the other one acting parallel to the panel:

²029.010sin

²166.0sin||, m

kNmkNgg kk =°×=×= a

²163.010cos

²166.0cos, m

kNmkNgg kk =°×=×=^ a

Wind suction4

Within the example, a panel spanning over zones G and H is assumed. The follow-ing pressure coefficients apply after interpolation between values for 5° and 15°slope:Zone G cp,1 = -1.75

cp,10 = -1.00Zone H cp,1 = -0.45

cp,10 = -0.75Parameter e is assumed to be e = 6 m, therefore width of zone G is 0,6 m adjacentto support No. 1 (end support). For design of fastenings, cpe is calculated for eachsupport, with size of the loaded area (see EN 1991-1-4, chapter 7.2.1) simply de-fined from mid of span to mid of span.Support No. 1, Zone G

( ) ( ) 59.165.1log00.175.175.1log2


²79.0

²50.059.110, m


4 Load not given in original example



Support No. 1, Zone H

( ) ( ) 68.065.1log45.075.075.0log2


²34.0

²50.068.010, m


Support No. 2 (intermediate support), Zone H

( ) ( ) 59.03.3log45.075.075.0log2


²30.0

²50.059.010, m


For support N. 3, zone H see support No. 1, zone H.

Fig. C.6: Wind loads

SnowSnow loads are treated here because of shear forces from roof thrust. The value

²75.0

²94.08.0

mkN

mkNss ki =×=×= m

applies. It is split into two components, one acting perpendicular to the panel andthe other one acting parallel to the panel:

²128.010sin10cos

²75.0sincos||, m

kNmkNss ii =°×°×=××= aa

²727.010cos10cos

²75.0coscos, m

kNmkNss ii =°×°×=××=^ aa

TemperatureFor colour group 2, the following values T1/T2 and DT apply for design::Winter temperature 0°C/+20°C (for combinations including snow, not

relevant for design of the fastenings)Winter temperature -20°C/+20°C DT = 40KSummer temperature +65°C/+25°C DT = -40K



Depending on national regulations, higher values for external temperature T1 applyfor ultimate limit state design. For fatigue limit state (head deflection), a tempera-ture difference of DT = T2 - T1 = -70 K applies for design.

C.3.3 Characteristic values of support reactions

Self-weightFor calculation of support reactions, the following parameters need to be calculat-ed:

( )115.0

330 22 =

×=

×=

cmmkN197

mkNcm2474198

LSB

2

Sb

075202474198

02100085882

2

4

21 .

mkNcm

cmkN

mcm.

BBBα

S

FF =+×

=+

=

1.11115.00752.0

0752.011=

×+

=×

+=

baal

( ) ( )( )

( ) ( ) 211.1tanh11214

cosh1cosh211215 2

1 =÷øö

çèæ -××++×

÷÷ø

öççè

æ×

-×-××++×

=

llba

lllbl

e

394,02

1 12 =-=

ee

For background information on parameters see Davies et al. (2001). The charac-teristic values of support reaction are

mkNm

mkNLgGG kkk 212.03.3394.0163.0 22,3,,1,, =××=××== ^^^ e

mkNm

mkNLgG kk 651.03.3211.1163.0 21,2,, =××=××= ^^ e

All shear forces are transferred via support No. 1.

mkNL

mkNLgG kk 190.02029.02 2||,1||,, =××=××=



SnowFor calculation of support reactions, the same parameters as for self-weight apply.The characteristic values of support reaction are

mkNm

mkNLsSS ikk 946.03.3394.0727.02,3,,1,, =××=××== ^^^ e

mkNm

mkNLsS ik 907.23.3211.1727.01,2,, =××=××= ^^ e

All shear forces are transferred via support No. 1.

mkNm

mkNLsS ik 845.03.32

²128.02||,1||,, =××=××=

Wind suctionSupport reactions for wind loads were determined by software.

TemperatureFor calculation of support reactions, the following parameters need to be calculat-ed:

( ) ( )( )

( ) 28.2tanh111

cosh1cosh2113 2

5 =÷øö

çèæ -××++

÷÷ø

öççè

æ×

-×-×+×

-=

llba

llla

e

14.125

6 -=-=e

e

cmkN

cm

CK

CK

eTT FF 4

55

1122 10735.0529.6

201102.1201102.1-

--

×=°-××-°××

=×-×

=aaq

For parameters a, b and l see above. The characteristic values of support reactionare

mkN

cmm

kNcmcmkN

LBTT

2

Skk 629.0

3300

247419810735.014.1

4

63,,1,, -=××

×-=×

×==

-

^^

qe

mkN

cmm

kNcmcmkN

LBT

2

Sk 259.1

3300

247419810735.028.2

4

53,, =××

×=×

×=

-

^qe



SummaryTransverse support reactions are summarised in the following table.

Table C.2: Characteristic values of support reactions [kN/m]Support Gk Wk Sk Tk,Summer Tk,Winter

1 0.212 -0.689 0.946 0.629 -0.6292 0.651 -1.249 2.907 -1.259 1.2593 0.212 -0.444 0.946 0.629 -0.629

C.3.4 Design values of support reactionsDifferent combinations need to be checked:

A Maximum shear force at support No. 1:

mkN

mkN

mkNSGV kFkFEd 524.1845.05.1190.035.11, =×+×=×+×= gg

mkNNEd 0.01, =

B Maximum tensile force at support No. 1:

mkN

mkNGV kFEd 190.0190.000.11, =×=×= g

,1 0 ,Winter

1.00 0.212 1.5 0.689 1.5 0.6 0.629 1.388

Ed F k F k F T kN G W TkN kN kN kNm m m m

g g g y= × + × + × ×

= × + ×- + × × - = -

C Maximum tensile force at support No. 2:

mkN

mkN

mkN

mkN

WTGN kWFSummerkFkFEd

362.2249.16.05.1259.15.1651.000.1

0,2,

-=-××+-×+×=

××+×+×= yggg

D Maximum tensile force at support No. 3:

mkN

mkN

mkN

mkN

WTGN kWFWinterkFkFEd

131.1444.06.05.1629.05.1212.000.1

0,3,

-=-××+-×+×=

××+×+×= yggg




C.3.5 Head deflectionFinally head deflection is checked. Analytical calculation of head deflection for mul-ti-span panels is based on method of consistent deformations. In a first step, headdeflection at end supports is calculated for the single span panel with Leqv = 2 L =660 cm and a temperature difference of DT = T2 - T1 = -70 K. As bending stiffnessof the profiled face has to be considered, calculation is more complex. For back-ground of stiffness values see references.

( )0293.0

660197

2474198

2

2

22 =×

=×

=cm

mkN

mkNcm

LSBβ

eqv

SL

0752.02474198

021000858.82

2

4

21 =+×

=+

=

mkNcm

cmkN

mcm

BBBα

S

FF

3220293007520

0752011

22 .

...

βααλ

LL =

×+

=×+

=

( )cmcm

KK

eT

eTT

eTT TTFTFT 11029.1

529.6

701102.14

5

1211,22, -

-

×-=-××

=×

=-×

=×-×

=Daaaa

q

Shear strain due to elastic shear deformation in the core is

3

4

2

2

1081.32

3.22tanh3.22

660110294.1

2tanh -

-

×=÷øö

çèæ×

××--=÷

øö

çèæ×

×-=

cmcmL L

L

eqvT

ll

qg


2

4

2

21

1059.32

3.22tanh3.22

121

0752.01

660110294.1

2tanh1

21

1

-

-

×-=úû

ùêë

é÷øö

çèæ×-×

+

××-=

úû

ùêë

é÷øö

çèæ×-×

+

×=

cmcm

L L

L

eqvT

lla

qg



Deflection at mid of span caused by temperature difference is

( )

( )( ) ( ) cm

cmcm

Lw

LL

eqvT

41.623.22cosh

113.22

810752.01

18

66011029.1

2cosh1181

11

8

2

24

222

2

=úû

ùêë

é÷÷ø

öççè

æ-×-×

+×

××-=

úû

ùêë

é÷÷ø

öççè

æ-×-×

+×

×=

-

llaq

Deflection at mid of span caused by a line load is

( ) úû

ùêë

é÷øö

çèæ×

××-

××+×

+×

=2

tanh8

14

1481 2

32

22

3L

LLDS

eqvF BB

LFw l

lala

and therefore

( ) ( )

( )( ) ( )

mkN

cm

mcm

cmkN

mkNcmcm

L

BBwwwFL

LLeqv

DSTTF

20.2

23.22tanh

3.220752.081

3.220752.041

481660

858.8210002474919741.6

2tanh

81

41

481

323

4

2

2

232

22

3

=

úû

ùêë

é÷øö

çèæ×

××-

××+×

÷÷ø

öççè

æ×+×

=

úû

ùêë

é÷øö

çèæ×

××-

××+×

+×==

llala

Shear strain due to elastic shear deformation in the core is

( )( )( )

( ) ( )( )

3

2

2

2

2

2

222

1019.5

3.22sinh5.013.22sinh5,010288.0

858.8210002474198

66020.2

sinh1sinh1

-×=

úûù

êëé -×

+-×××+

×=

úû

ùêë

é -×+-×

+××

=

mcm

cmkN

mkNcm

cmcmkN

BBLF

L

L

DS

LeqvA l

eleb

g


( )

( )( )

2

22

2

2

2

222

2

1

1074.2

23.22tanh

21

3.220752.01

161

858.8210002474194

66005.2

2tanh

211

161

-×=

úû

ùêë

é÷÷ø

öççè

æ÷øö

çèæ-×

×-×

×+

×=

úû

ùêë

é÷÷ø

öççè

æ÷øö

çèæ-×

×-×

+

×=

mcm

cmkN

mkNcm

cmmkN

BBLF L

LDS

eqvF

lla

g



The angles g1 resulting from shear deformation of the core at end support and gresulting from bending rotation have to be subtracted from each other. Head de-flection is finally calculated using

( ) ( )( ) ( ) cmcm

eDeDu FTFFTF

110,0529,61019,51018,30,61074,21059,3 3322111

-=××+×-××+×-=

×+-×+=×-×=----

gggggg

with distance DF between supporting structure and head of fastener, i.e. DF = dbecause of fastening in the trough.

C.3.6 Resistance and Verifications

Pull-through resistanceThe panel will be fastened by crest fastenings without a saddle washer. Self-tapping screws 6.3 x L made of stainless steel and washers dW = 19 mm withcured-on elastomer seals were used.External face is made from structural steel S320GD+Z275 (fu,F1 = 390 N/mm²) ac-cording to EN 10346, nominal thickness is tnom,F2 = 0.60 mm with special toleranceaccording to EN 10143.Design core sheet thickness of the external face:


Characteristic value of pull-through resistance:

( )

( )

N

emmmm

Nmmmmmm

Nmm

N

edftdfEN

mmmm

bd

WFuFWCcCcIRk

w

1968

45.055.01939056.065.01911.05.321.2

45.055.065.021.2

2

2

1

35198

22

22

8

1,12

,

=

÷÷

ø

ö

çç

è

æ×+×÷÷

ø

öççè

æ×××+×××=

÷÷÷

ø

ö

ççç

è

æ×+××××+×××=

÷øö

çèæ

××-

÷÷ø

öççè

æ×

×-

p

p

Design value of pull-through resistance

kNNNN

M

IRkIRd 48.1

33.11968,

, ===g

Verification, with three fasteners per meter width at base support and two fasten-ers per meter width at intermediate and top supports

0.131.048.13

388,1

,

1,

,

1, <=×

==åå kN

kNN

NN

N

IRd

BEd

IRd

Ed

0.180.048.12

362,2

,

2,

,

2, <=×

==åå kN

kNN

NN

N

IRd

CEd

IRd

Ed



0.138.048.12

131,1

,

3,

,

3, <=×

==åå kN

kNN

NN

N

IRd

DEd

IRd

Ed

Pull-out resistanceThe characteristic value of pull-out resistance is taken from the ETA of the fasten-er, see Fig. C.8. As there are only characteristic values of tensile resistance (mini-mum value of pull-through resistance and pull-out resistance) given, pull-out re-sistance will be used for maximum thickness tnom,F1 (in ETAs often designated astN,F1).



Fig. C.8: Annex of the ETA with pull-out resistance



Characteristic value of pull-out resistancekNN IIkR 00.5,, =


kNkNNN

M

IIRkIIRd 76.3

33.100.5,

, ===g


0.112.076.33

388,1

,

1,

,

1, <=×

==åå kN

kNN

NN

N

IIRd

BEd

IIRd

Ed

0.131.076.32

362.2

,

2,

,

2, <=×

==åå kN

kNN

NN

N

IIRd

CEd

IIRd

Ed

0.115.076.32

131.1

,

3,

,

3, <=×

==åå N

kNN

NN

N

IIRd

DEd

IIRd

Ed

Shear resistanceThe characteristic values of shear resistance were taken from the ETA of the fas-tener, see Fig. C.9. The ETA does not differentiate between VRd, VRd,I and VRd,II.Values depend from sheet thickness of the supporting structure tII (in ETAs oftendesignating the nominal thickness) and sheet thickness of the internal face tnom,F2

(in ETAs often designated as tN,F2) and cover both sheets.Supporting structure is made from structural steel S235JR (fu,II = 360 N/mm²) withthickness tnom,II = 5.0 mm. Internal face is made from structural steelS320GD+Z275 (fu,F2 = 390 N/mm²) according to EN 10346, nominal thickness istnom,F2 = 0.50 mm.

Characteristic value of shear resistance:kNVRk 98.0=


kNkNVVM

RkRd 74.0

33.198.0

===g

Verification, with three fasteners at support No. 1

0.169.074.03

524.11,1, <=×

==åå kN

kNV

VV

V

Rd

AEd

Rd

Ed



Fig. C.9: Annex of the ETA with shear resistance



InteractionInteraction verification has to be made for supporting structure only. While forNRd,II, a specific value was derived in this example, the ETA does not differentiatebetween VRd, VRd,I and VRd,II.Verification, with three fasteners at support No. 1

0.121.009.012.074.03

190.076.33

388.11,

,

1,

,

1,

,

1, <=+=×

+×

=+=+kNkN

kNkN

VV

NN

VV

NN

Rd

AEd

IIRd

AEd

IIRd

Ed

IIRd

Ed

Allowable head deflectionThe allowable head deflection is taken from the ETA of the fastener, see Fig. C.8.

mmu 18max =Verification

0.106.080.111.0

max<==

cmcm

uu



Fig. C.10: Annex of the ETA with allowable head deflection



C.4 Roof panel

C.4.1 SystemRoof panel, lying over two spans with L = 3300 mm, with a slope of 10°. The panelhas a profiled external face with pitch of profile p = 333 mm and width of the crestb1 = 35 mm. The internal face is lightly profiled. The nominal thickness is 60 mm,the thickness at crest is D = 98 mm.


External face is made from structural steel S320GD+Z275 (fu,F1 = 390 N/mm²) ac-cording to EN 10346, nominal thickness is tnom,F1 = 0.60 mm with special toleranceaccording to EN 10143. Internal face is made from structural steel S320GD+Z275(fu,F2 = 390 N/mm²) according to EN 10346, nominal thickness is tnom,F2 = 0.50 mmwith special tolerance according to EN 10143.The core material is polyurethane foam with shear modulus GC = 3.02 N/mm²,compression modulus 3.5 N/mm² (not given in original examples) and compressionstrength 0.11 N/mm².The panel will by fastened by crest fastenings, using washers dw = 16 mm withcured-on elastomer seals (no saddle washers). At base support (support No. 1),there are three fasteners per panel of 1 m width and per support, with each crestfastened. At intermediate and top support (supports No. 2 and No. 3), there aretwo fasteners per panel of 1 m width and per support, with two crests fastened andone crest unfastened per panel. Self-drilling screws 6.0 x 140 mm made of stain-less steel are used.Supporting structure is a purlin made of glued laminated timber GL 24h accordingto EN 14080 in service class 2, characteristic value of density is rk = 380 kg/m³.Shear forces from self-weight loading are transferred only by support No. 1, seeFig. C.11.Chapter C.3 deals with the identical system and sandwich panel, but fastened on asupporting structure made of hot-rolled sections made from structural steel using adifferent type of fastener.



C.4.2 Actions and loadsSee chapter C.3.2.

C.4.3 Characteristic values of support reactionsSee chapter C.3.3 and summary in the following.

Transverse support reactions are summarised in the following table.

Table C.3: Characteristic values of support reactions [kN/m]Support Gk Wk Sk Tk,Summer Tk,Winter

1 0,212 -0,689 0,946 0,629 -0,6292 0,651 -1,249 2,907 -1,259 1,2593 0,212 -0,444 0,946 0,629 -0,629

All shear forces are transferred via support No. 1:

mkNGk 190.01||,, =

mkNSk 845.01||,, =

C.4.4 Design values of support reactionsTimber supporting structures require consideration of service class and load dura-tion class. Due to the different modification factors kmod linked with the action withthe shortest duration of a given combination, some more combinations have to bechecked. See following table for modification factors kmod applied in the example.

Table C.4: Loading, load duration class and modification factor kmod forglued laminated timber according to EN 14081 in service class 2.

loading Load duration class kmod

self-weight Gk permanent 0.60temperature Tk long-term 0.70

snow Sk medium-term 0.80

wind Wkshort-term to

instantaneous1.00

If a load combination consists of actions belonging to different load-duration clas-ses a value of kmod should be chosen which corresponds to the action with theshortest duration, see EN 1995-1-1. In this particular case for a combination of



wind action and temperature action, a value of kmod corresponding to the wind ac-tion should be used, while for a combination of temperature action only, the small-er value of kmod corresponding to the temperature action applies.For component I (sandwich panel) only combinations A, C, E and G with maximumshear force or maximum tensile force need to be verified.

A Maximum shear force at support No. 1:

mkN

mkN

mkNSGVV kFkF

AEdEd 524,1845,05,1190,035,11,1, =×+×=×+×== gg

mkNNN A

EdEd 0.01,1, ==

B Shear force at support No. 1 with smallest kmod:

mkN

mkNGVV kF

BEdEd 257.0190.035.11,1, =×=×== g

mkNNN B

EdEd 0.01,1, ==

C Maximum tensile force at support No. 1:

mkN

mkNGVV kF

CEdEd 190.0190.000.11,1, =×=×== g

,1 ,1 0 ,Winter

1.00 0.212 1.5 0.689 1.5 0.6 0.629 1.388

CEd Ed F k F k F T kN N G W T

kN kN kN kNm m m m

g g g y= = × + × + × ×

= × + ×- + × × - = -

D Tensile force at support No. 1 with smallest kmod:

mkN

mkNGVV kF

DEdEd 190.0190.000.11,1, =×=×== g

,1 ,1 ,Winter

1.00 0.212 1.5 0.629 0.732

DEd Ed F k F kN N G T

kN kN kNm m m

g g= = × + ×

= × + × - = -

E Maximum tensile force at support No. 2:

mkN

mkN

mkN

mkN

WTGNN kWFSummerkFkFEEdEd

362.2249.16.05.1259.15.1651.000.1

0,2,2,

-=-××+-×+×=

××+×+×== yggg



F Tensile force at support No. 2 with smallest kmod:

mkN

mkN

mkN

TGNN SummerkFkFFEdEd

238.1259.15,1651.000.1

,2,2,

-=-×+×=

×+×== gg

G Maximum tensile force at support No. 3:

mkN

mkN

mkN

mkN

WTGNN kWFWinterkFkFGEdEd

131.1444.06.05.1629.05.1212.000.1

0,3,3,

-=-××+-×+×=

××+×+×== yggg

H Tensile force at support No. 3 with smallest kmod:

mkN

mkN

mkN

TGNN WinterkFkFHEdEd

732.0629.05,1212.000.1

,3,3,

-=-×+×=

×+×== gg


C.4.5 Head deflectionSee chapter C.3.5.

C.4.6 Resistance and Verifications

Pull-through resistanceThe panel will by fastened by crest fastenings without a saddle washer. Self-drillingscrews 6.0 x 140 mm made of stainless steel and washers dW = 16 mm with cured-on elastomer seals were used.External face is made from structural steel S320GD+Z275 (fu,F1 = 390 N/mm²) ac-cording to EN 10346, nominal thickness is tnom,F2 = 0.60 mm with special toleranceaccording to EN 10143.Design core sheet thickness of the external face:


Characteristic value of pull-through resistance:



( )

( )

N

emmmm

Nmmmmmm

Nmm

N

edftdfEN

mmmm

bd

WFuFWCcCcIRk

w

1747

45.055.01639056.065.01611.05.321.2

45.055.065.021.2

2

2

1

35168

22

22

8

1,12

,

=

÷÷

ø

ö

çç

è

æ×+×÷÷

ø

öççè

æ×××+×××=

÷÷÷

ø

ö

ççç

è

æ×+××××+×××=

÷øö

çèæ

××

-

÷÷ø

öççè

æ×

×-

p

p

Design value of pull-through resistance

kNNNN

M

IRkIRd 31.1

33.11747,

, ===g


0.135.031.13

388,1,

1, <=×

=å kN

kNN

N

IRd

Ed

0.190.031.12

362,2,

2, <=×

=å kN

kNN

N

IRd

Ed

0.143.048.12

131,1,

3, <=×

=å kN

kNN

N

IRd

Ed

Pull-out resistanceSupporting structure is a purlin made of glued laminated timber GL 24h accordingto EN 14080, characteristic value of density is rk = 380 kg/m³.The characteristic withdrawal strength perpendicular to the direction of grain is un-known but can be calculated.

2

2

3626

, 1.1038010701070mm

Nmkgf kkax =÷

øö

çèæ××=××= -- r

Effective lengthmmmmmmDLlg 4298140 =-=-=

mmdmmmmmmlll bgef 30537542 =×³=-=-=

Load-bearing capacity for one fastener

kN

mkg

mkg

mmmmmm

N

mkgldfF k

efkaxRkax 39.2350

380370.61.10

350

8,0

3

3

2

8,0

3

,, =÷÷÷

ø

ö

ççç

è

æ×××=

÷÷÷

ø

ö

ççç

è

æ×××=

r

Characteristic value of pull-out resistance

mod,, kFN RkaxIIRk ×=




M

Rkax

M

IIRkIIRd

kFNN

ggmod,,

,

×==

Verification, with three fasteners per meter width at base support and two fasten-ers per meter width at intermediate and top supportsC Maximum tensile force at support No. 1:

0.125.0

33.100.139.23

338.1mod,

1,

,

1, <=×

×=

×=

åå kNkN

kFN

NN

M

CRkax

CEd

IIRd

Ed

g


0.119.0

33.170.039.23

732.0mod,

1,

,

1, <=××

=×

=

åå kNkN

kFN

NN

M

CRkax

DEd

IIRd

Ed

g

D Maximum tensile force at support No. 2:

0.166.0

33.100.139.22

362.2mod,

2,

,

2, <=××

=×

=

åå kNkN

kFN

NN

M

CRkax

EEd

IIRd

Ed

g

E Tensile force at support No. 2 with smallest kmod:

0.149.0

33.170.039.22

238.1mod,

2,

,

2, <=××

=×

=

åå kNkN

kFN

NN

M

CRkax

FEd

IIRd

Ed

g

G Maximum tensile force at support No. 3:

0.131.0

33.100.139.22

131.1mod,

3,

,

3, <=××

=×

=

åå kNkN

kFN

NN

M

CRkax

GEd

IIRd

Ed

g

H Tensile force at support No. 3 with smallest kmod:

0.129.0

33.100.139.22

732.0mod,

3,

,

3, <=××

=×

=

åå kNkN

kFN

NN

M

CRkax

HEd

IIRd

Ed

g

Shear resistanceAt base support there are two screws per panel of 1 m width.Dimensions of self-drilling screws 6.0 x L made of stainless steel:d = 6.0 mmd1 = 3.9 mm

mmmmddef 3.49.31.11.1 1 =×=×=



Internal face is made from structural steel S320GD+Z275 (fu,F2 = 390 N/mm²) ac-cording to EN 10346, nominal thickness is tnom,F2 = 0.50 mm with special toleranceaccording to EN 10143.Design core sheet thickness of the internal face:


Characteristic value of shear resistance:

( ) Nmm

NmmmmfdtV FuFIRk 10093909.346.02.42.4 23

2,13

2, =×××=×××=


kNNVVV

M

IRkIRdRd 76.0

33.11009,

, ====g

Verification, with three screws at base support

0.167.076.03

524,11, <=×

=å kN

kNV

V

Rd

Ed

Supporting structure is a purlin made of glued laminated timber GL 24h accordingto EN 14080, characteristic value of density is rk = 380 kg/m³.The characteristic embedment strength for fastenings with predrilled holes (includ-ing fastenings with self-drilling screws) is calculated with

( ) ( ) 23, 8,293803,401.01082.001.01082.0mm

Nmkgmmdf kefkh =××-×=××-×= r

The characteristic yield moment of fastener is unknown but can be calculated.

( ) NmmmmmmNdfM efSGuRky 66543.45003.03.0 6.2

26.2

,, =××=××=

Load-bearing capacity for one fastener

kNkNkN

kNkNkN

kNmmmm

NNmm

mmmmmm

N

FdfM

dtfF Rkax

efkhRky

efkh

RkV

90.110.290.1

min

60.050.190.1

min

439.23.48.296654215.1

3.4378.294.0min

4215.1

4.0min

2

2

,,,

1,

,

=îíì

=

îíì

+=

ïïî

ïïí

ì

+××××

×××=

ïî

ïíì

+××××

×××=

The limitation

efkhRkyRkax dfM

F××××£ ,,

, 215.14

is fulfilled.



The characteristic value of shear resistance of the timber supporting structure(component II) is

mod,, kFV RkVIIRk ×=


M

IIRkIIRd

VV

g,

, =

For a combination with wind action being the action with shortest load durationkNkNkFV RkVIIRk 90.10.190.1mod,, =×=×=

kNkNVV

M

IIRkIIRd 43.1

33.190.1,

, ===g

For a combination with temperature action being the action with shortest load dura-tion

kNkNkFV RkVIIRk 52.18.090.1mod,, =×=×=

kNkNVV

M

IIRkIIRd 14.1

33.152.1,

, ===g

For a combination with snow action being the action with shortest load durationkNkNkFV RkVIIRk 33.17.090.1mod,, =×=×=

kNkNVV

M

IIRkIIRd 00.1

33.133.1,

, ===g

For a combination with self-weight action being the action with shortest load dura-tion

kNkNkFV RkVIIRk 14.16.090.1mod,, =×=×=

kNkNVV

M

IIRkIIRd 86.0

33.114.1,

, ===g

Verification, with three fasteners at base supportA Maximum shear force at support No. 1:

0.174.0

33.180.014.13

524.1

mod,

1,

,

1, <=×

×=

×=

åå kNkN

kFV

VV

M

ARkV

AEd

IIRd

Ed

g

B Shear force at support No. 1 with smallest kmod:

0.117.0

33.160.014.13

257.0

mod,

1,

,

1, <=×

×=

×=

åå kNkN

kFV

VV

M

BRkV

BEd

IIRd

Ed

g

Interaction



Interaction verification has to be made for supporting structure only.Verification, with three fasteners at base supportC Maximum tensile force at support No. 1:

0.132.007.025.0

33.100.114.13

190.0

33.100.139.23

338.1

mod,

1,

mod,

1,

,

1,

,

1,

<=+=×

×+

××

=

×+

×=+

åååå

kNkN

kNkN

kFV

kFN

VV

NN

M

CRkV

CEd

M

CRkax

CEd

IIRd

Ed

IIRd

Ed

gg


0.130.010.019.0

33.170.014.13

190.0

33.170.039.23

732.0

mod,

1,

mod,

1,

,

1,

,

1,

<=+=×

×+

××

=

×+

×=+

åååå

kNkN

kNkN

kFV

kFN

VV

NN

M

DRkV

DEd

M

DRkax

DEd

IIRd

Ed

IIRd

Ed

gg

Allowable head deflectionThe allowable head deflection is taken from the ETA of the fastener, see Fig. C.8.

mmmmmmdu C 2.46007.007.0max =×=×=

Verification

0.126.042.011.0

max<==

cmcm

uu

CIB General SecretariatVan der Burgh weg 12628 CD DelftThe NetherlandsE-mail: [email protected]

CIB Publication 418 / ISBN 978-9063-63-09-73

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