Fixation of Sandwich Panels, Mechanism and Innovations• Load bearing capacity depends first and foremost linearly ... Source: UEAtc Technical Report for the assessment of installations

Dirk H. Urbanek

Fixation of Sandwich Panels16.09.2010

Germany • Indiawww.zbn.de

Competence in light-weight constructions• advise, development,• design, structural analysis• supervision, expertise, certification worldwide

Fixation of Sandwich Panels,Mechanism and Innovations

Dirk H. Urbanek

Fixation of Sandwich Panels16.09.2010 Overview

1. Conventional FixationsWhy Does It Happen to Work?

2. Hidden FixationsDesign versus Limitations?

3. Innovative FixationsWhat is That All About?

Dirk H. Urbanek


Conventional Fixations → Visible Fixations

● The load bearing mechanism is not really understood

● Tiny washer areas carry surprisingly high loads

● The inevitableness of bulges

Dirk H. Urbanek


Conventional Fixations

Comparison of Supports and Fixations

Dirk H. Urbanek



Contemporary Test Set-ups are diffuse

Sou

rce:

EN

145

09:2

006-

11

Dirk H. Urbanek



Simple Sandwich Theory Does not Cover Point Impacts

Sou

rce:

Y. F

rost

ig, M

. Bar

uch,

O. V

ilnay

, I. S

hein

man

:H

igh-

Ord

er T

heor

y fo

r San

dwic

h-B

eam

Bea

vior

with

Tra

nsve

rsel

y Fl

exib

le C

ore

Dirk H. Urbanek



Research at the Technical University of Dortmund

Sou

rce:

AiF

-Res

earc

h P

roje

ct 1

6066

N

Goals of Part I (partly and shortened):

Development of realistic calculation models of transversely

acting sandwich fixations.

Thus allow the structural and constructive design and

optimisation of new fastening systems without approval

AIF-Research Project 16066 N„Innovative Anchorage of Sandwich Elements“

Dirk H. Urbanek




Sou

rce:

AiF

-Res

earc

h P

roje

ct 1

6066

N

AIF-Research Project 16066 NApproach to Part I

Dirk H. Urbanek




Preliminary Results of Part I:

• Load bearing capacity depends first and foremost linearly

on the thickness of the adjacent steel layer and

on the diameter of the washer.

• The influence of the core stiffness,

the pressure resistance, and

the thickness of the element

are more or less negligible.

• Bulges are – as ever known – unavoidable.

Dirk H. Urbanek



Unavoidable Bulges

Dirk H. Urbanek


Hidden Fixations → Civil Engineer´s Nightmare?

● The fixations become structurally decisive

● Contemporary systems do not pardon any mistake nor accident

● Load spreading inlays are prone to be not reliably watertight

● Linear Sandwich Theory is Scarcely Applicable only

Dirk H. Urbanek


Hidden Fixations

Fixations Become Structurally Decisive, Reason I and II

Source: Versuchsanstalt für Stahl, Holz und Steine, Universität Karlsruhe - Bericht Nr.: 061505

● The load bearing capacity of marginal fixations is low

● There are only few fixation possibilities.

Roughly estimated reduction factor (20mm ≤ e ≤ 45mm):

Maximal number of screws per square meter:

Dirk H. Urbanek


Hidden Fixations

Fixations Become Structurally Decisive, Reason III

The fixation has to be achieved by a positive lock

Dirk H. Urbanek


Hidden Fixations

Limitation of Possible Span Widths by Hidden Fixation

Sou

rce:

ZB

N C

ivil

Eng

inee

rsLT

D

Hidden

Visible

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

1-span2-spans

3-spans

3.25

1.90 2.20

4.254.15 4.25

Hidden

Visible

Dirk H. Urbanek


Hidden Fixations

Invisibly Fixed Sw-Panels are rather Plates but not Beams

Sou

rce:

ZB

N C

ivil

Eng

inee

rsLT

D

Dirk H. Urbanek


Hidden Fixations

Invisibly Fixed Sw Panels are Difficult to Replace

Sou

rce:

ZB

N C

ivil

Eng

inee

rsLT

D

Dirk H. Urbanek


Hidden Fixations

Load Spreading Plates are Commonly not Sealed

Sou

rce:

App

rova

l Z-1

0.4-

440

Dirk H. Urbanek


Innovative Fixations → an Attempt at Walking

● Fixations at one face only are urgently required

● Fixations at one face only are currently not in reach

● Constructive alternatives might be possible

Dirk H. Urbanek


Innovative Fixations

Fixation of Solar Systems, Racks, Ducts, Lamps, or ...

Sou

rce:

ww

w.sc

hlet

ter.d

e

Dirk H. Urbanek



Research at Technical University of Dortmund

Goals of Part II (partly and shortened):

Design, dimensioning, and optimisation of anchorage systems

at the inner face of sandwich elements.

Development of computational tools for the economical

dimensioning of these anchorage systems.

Provision of design rules in terms of economical production

and simple on-site assembly.

Sou

rce:

AiF

-Res

earc

h P

roje

ct 1

6066

N


Dirk H. Urbanek



Research at Technical University of DortmundAIF-Research Project 16066 NInnovative Anchorage of Sandwich Elements

Sou

rce:

AiF

-Res

earc

h P

roje

ct 1

6066

N

Dirk H. Urbanek




-

0.20

0.40

0.60

0.80

1.00

1.20

1.40

- 2 4 6 8

Forc

e [k

N]

Displacement [mm]

Lifting Force

Dirk H. Urbanek




Dirk H. Urbanek


Sou

rce:

UE

Atc

Tec

hnic

al R

epor

t for

the

asse

ssm

ent o

fin

stal

latio

ns u

isng

san

dwic

h pa

nels

with

aC

FC-fr

ee p

olyu

reth

ane

foam

cor

-19

96



Dirk H. Urbanek



Research at Technical University of Dortmund

Realisation due to the very first tests (Part II):

There is no easy way to fix reasonable loads at one steel

skin only.

The applicable forces are disappointingly small.


Dirk H. Urbanek



Alternatives?

Source: ZBN Civil Engineers LTD

Dirk H. Urbanek


Résumé

● Even the traditional visible fixation ought to be further examined

● Hidden fixations provide many disadvantages and all of which are inherent

● Real innovations are not in sight and will demand some additional efforts

Slide Number 1Slide Number 2Slide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Slide Number 29Slide Number 30Slide Number 31Slide Number 32Slide Number 33Slide Number 34

Documents

Fixation of Sandwich Panels, Mechanism and Innovations• Load bearing capacity depends first and foremost linearly ... Source: UEAtc Technical Report for the assessment of installations