2011-10-07_Hand Out_Ithaca_Harm. of Interpr. en 15512

ERF - FEM R&S / ECCS TWG 7.5 / RMI

Ithaca / USA ; 10 October 2011

HARMONIZATION of the

INTERPRETATION OF EN 15 512 1

ECCS / TC 7.5 & RMI

Ithaca – USA / October 2011

European Racking Federation ERF / FEM Racking & Shelving

HARMONIZATION OF THE

INTERPRETATION OF EN 15512

“Non-conflicting additional information” to EN 15512, coming from

● ECCS – TWG 7.5 / ERF-FEM R&S Work Shop “Testing” ● Discussions with regard to the German situation : “allgemeine bauaufsichtliche Zulassung”

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Kees Tilburgs

Technical Chairman ERF / FEM R&S

October 2011

EN 15 512

HARMONIZATION OF INTERPRETATION 1

ECCS / TC 7.5 & RMI



EN 15 512

HARMONIZATION OF INTERPRETATION

Parties involved in the “Interpretation”

● Rack designers ● Persons involved in the submission of a Building Permit, when required - Professional Engineers (“Prüfstatiker”) - Authorities (“Dienst Bouwtoezicht”) ● Quality Mark Institutions ● Independent experts, approached in case of a conflict with the client , or to investigate a collapse ● CEN/TC 344 Committee , when considering a possible review of EN 15512

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ECCS / TC 7.5 & RMI



A. BEAM LOAD CAPACITY

A.1 9.6 Beams subject to bending and torsion

See Note “- - - - . For open cross sections and/or slender beams together with unsymmetrical beams of open cross- section, testing is usually necessary.”

- Slender box-shaped 2 C-beams (2nd order torsion) - Sigma beams, usually used in rack-clad structures

POSITIVE RESTRAINING

EFFECT OF PALLETS IS RELEVANT

EN 15 512


ECCS / TC 7.5 & RMI


European Racking Federation ERF / FEM Racking & Shelving 4

EN 15 512 HARMONIZATION OF INTERPRETATION

BEAM LOAD CAPACITY

Bending of the pallet is reality :

has a negative effect on beam load capacity

shall be included in a test with real pallets !!!





ECCS / TC 7.5 & RMI



EN 15 512


See A.2.10 Bending tests on beams, NOTE 1

“It is important that the loading media interact with the beams in the same way as in practice”

Dynamic effects during depositing / picking will have a negative effect on the friction between pallet and supporting beam surface

Temporarily loss of “diaphragm” action of the pallets on a pair of beams

5

BEAMS IN BENDING & TORSION

ECCS / TC 7.5 & RMI



EN 15 512


Possible consideration of negative effect of dynamics

6

BEAMS IN BENDING & TORSION

Load factor : 1.25 ??? Number of deposits : 25 ??? nstab ≥ 20 OK ???

Rotation φ





ECCS / TC 7.5 & RMI



EN 15 512


A.2 A.2.10 Bending tests on beams

Possible failure mode : Instability of the compressed upper flange

Relevant parameter when loading via pallets : Distance between 2 adjacent pallets

● Nominal distance depends on load overhang yes/no overhang all sides : 50 mm nominal = 75+2x50 = 175 mm

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● Placement tolerances to be considered ??? e.g. 175 + 2 x 50 = 275 mm ???

BEAM LOAD CAPACITY

ECCS / TC 7.5 & RMI



EN 15 512


BENDING TEST ON BEAMS

Cross-aisle displacement

loading equipment

shall be possible (no restraining effect

wrt possible beam instability)

A possible failure mode : “Crippling

in the compressed zone”

Pallet clotch dimension

also relevant !!!





ECCS / TC 7.5 & RMI



A.3 9.4.6 Beams as tie beams in

braced pallet racks

EN 15 512


In case of Σ – beams (regularly used in clad rack structures) , testing is needed for a cost-effective design. Such racking is in general braced in down-aisle direction

Braced racking “Tie beam function”

Bending & Compression

Compression shall be included in the testing !!!

BEAM LOAD CAPACITY

ECCS / TC 7.5 & RMI



BEAM LOAD CAPACITY IN BRACED RACKING

BEAM ALSO IN COMPRESSION

2-Span situation

EN 15 512






ECCS / TC 7.5 & RMI



EN 15 512


Σ BEAM LOAD CAPACITY IN BRACED RACKING

Worst case bending for 3 – span :

Load only

on outer rack compartments

Horizontal compression load

introduction ,

because tie beam function

ECCS / TC 7.5 & RMI



EN 15 512



Examples of possible failure modes :

- Local buckling of compressed flange

- Torsional flexural instability





ECCS / TC 7.5 & RMI



EN 15 512



Loading situation for :

- Maximum bending moment at support

- Maximum shear force

ECCS / TC 7.5 & RMI



EN 15 512


B. UPRIGHT LOAD CAPPACITY

B.1 EFFECT OF DISTORTIONAL BUCKLING

Reference to Presentation Nedcon (Oct. 2011) “Determination Critical Load Upright in a Pallet Racking”

However, an a-symmetrical mode might be determinative





ECCS / TC 7.5 & RMI



EN 15 512


B.2 Bending perpendicular to upright frame

A.2.9 Bending tests on Upright sections

Reference to Presentation Nedcon (Oct. 2011)

“Upright frame bending test :

Load application and support condition”

● Problem was :

excessive upright torsion in case of a certain

frame bracing node point.

ECCS / TC 7.5 & RMI



EN 15 512


● Positive effect in reality :

- Determinative upright part never in top-most position

- Bottom upright part always at one end

in direct contact with floor

torsional restraint due to friction

between base plate and floor

This end condition

is never relevant

BENDING TEST UPRIGHT FRAME





ECCS / TC 7.5 & RMI



EN 15 512


● Proposal

a. Load application : do not change

b. End condition at both sides of the upright frame :

it is allowed to have an additional frame panel with

system length 750 mm


Add an extra bracing member before the first horizontal bracing member.

Additional rotation restraint & strength at this position.

~ 750 mm

ECCS / TC 7.5 & RMI



EN 15 512


c. Failure of the upright in bending (and torsion) is

also affected by deformations and possible failure

of the frame bracing

In case relevant, also to be corrected for actual thickness and yield stress of the bracing members






ECCS / TC 7.5 & RMI



C. A.2.8 TESTS FOR THE SHEAR STIFFNESS

OF UPRIGHT FRAMES

EN 15 512


Top view

ECCS / TC 7.5 & RMI



EN 15 512


UPRIGHT FRAME SHEAR TEST





ECCS / TC 7.5 & RMI



EN 15 512


b. Presentation TU Trento, December 2010 A new text proposal for A.2.8.3 (Method) and A.2.8.5 (Evaluation) is given, including cyclic tests, however for the future:

● Tests : - Comparative tests

- Tests under cyclic reversal loads

- EN procedure Australian procedue

● FE Studies : Numerical study on the tested upright frames

UPRIGHT FRAME SHEAR TEST : References

ECCS / TC 7.5 & RMI



EN 15 512


C.2 Relevant aspects for consideration

a. Level of shear force when slip of a bolted connection will occur, depends on the “non intentional” or “intentional” tension pre-load, causing certain slip resistance due to friction in the bolted connection.

● Thin gauged material Reliability pre-load with time ?)

● Type of bolt securing (e.g. “nyloc” nuts) has an influence

● Assembling of test frames in accordance with “Assembling Instruction” Possible scatter

UPRIGHT FRAME SHEAR TEST





ECCS / TC 7.5 & RMI



EN 15 512


b. Different approach in case of seismic design

1. Much higher levels of shear force

2. – Static strength Minimum stiffness values relevant – Seismic strength Maximum stiffness values relevant (higher horizontal seismic force)

C.3 Final Conclusion (Static + Seismic)

Still to be agreed !!!

UPRIGHT FRAME SHEAR TEST : Aspects for consideration

ECCS / TC 7.5 & RMI



D. A.2.7 TESTS ON FLOOR CONNECTIONS

EN 15 512


D.1 Presentation TU Barcelona (Dec. 2010)

Symmetrical test set-up (Fig. A.11) could give practical problems in the test execution

Proposal is made for an equivalent set-up for testing one floor connection at the time

● Set of transducers to measure ? As close as possible to the floor cq base plate bracket

● Transduces has to be capable of acting in compression and tension





ECCS / TC 7.5 & RMI



EN 15 512


TEST ON FLOOR CONNECTIONS

One test sample per test Vertical load introduction into upright

ECCS / TC 7.5 & RMI



D.2 Each test at a certain axial load level

until failure ??

EN 15 512


It is not clear from A.2.7 that at each level of Faxial

(Note : Number of levels is not specified!!)

the test sample shall be loaded by M until failure ,

as is assumed in Presentation TU Barcelona.

Allthough it might be concluded from A.2.7.5






ECCS / TC 7.5 & RMI



D.2.1 No Anchoring

Low Faxial compared to Fd(esign)

Actual rack load << γ X (Allowable Load)

In reality also low M Compared to Md(esign)

Ultimate load situation not relevant

EN 15 512



ECCS / TC 7.5 & RMI



EN 15 512


To minimize the number of tests, the following might be acceptable (TNO method)

1. Rotation spring stiffness KαFd;i

to be determined at the following load steps:

α = 0.1 ; 0.2 - - - 0.7 Max Fax = 0,7 Fd

Fd = design value axial strength from stub column test

2. MαFd;max from

(α Fd) / Fd + (MαFd;max ) / Md = 0.8

Md = design value bending strength upright






ECCS / TC 7.5 & RMI



EN 15 512


and also to be fulfilled ( because non-anchored) :

MαFd;max ≤ ½ x b x FαFd b = width of upright in plane of bending

3. Loading cycles at test situation αFd - from M = 0 M = + MαFd;max - from + MαFd;max – MαFd;max

- from – MαFd;max M = 0


ECCS / TC 7.5 & RMI



EN 15 512


4. Measured M - φ Curve

for Faxial = α Fd

5. Test result






ECCS / TC 7.5 & RMI



6. Strength check

Upright cross section just above floor level :

F / Fd + M / Md ≤ 1.0

M ≤ ½ b Fd (Because non-anchored)


EN 15 512


ECCS / TC 7.5 & RMI



D.2.2 Anchored base plate

EN 15 512


1. Condition MαFd;max ≤ ½ b FαFd is not required anymore

2. Md1 = design value bending strength upright

Md2 = design value bending strength anchoring ,

however depends on αFd

At each specified (!!!) level of αFd

to be tested until failure ??!!






ECCS / TC 7.5 & RMI



D.3 Concrete block

EN 15 512


a. Ensuring Class B 20/25 ??? Allowed scatter ???

b. Criterion for replacement ??? - No anchoring + good base plate design After each test : check concrete surface No crushing (criterion ???) Use again - Anchoring + good base plate design When slip of the anchor is observed ??? to be measured When failure of concrete or anchor ??? - At least after 50 Tests ???


ECCS / TC 7.5 & RMI



E. INTERPOLATION OF TEST RESULTS

EN 15 512


Reference : Presentation DIBt (Dr. Kathage)

in Dortmund – December 2010

e.g. with regard to beam to upright connections :

“EN 15512 gives no information concerning interpolation”





ECCS / TC 7.5 & RMI



EN 15 512


EN 15512 (A.2.4.1)

“All combinations of these factors, which occur in the

design of the structural system, shall be tested

separately, unless it can be reasonably

demonstrated that interpolation of results provides

a conservative estimate of performance”

Guidance with regard “conservative estimate” is useful ,

to avoid possible problems afterwards ,

when being checked by a “third party”.

NO GUIDANCE YET

INTERPOLATION BETWEEN TEST RESULTS

ECCS / TC 7.5 & RMI



F. TESTING PRINCIPLES ACTUAL SET-UP

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Each testing standard, also Annex A of EN 15512, gives :

● Principles (end conditions, load application etc.) ● Simplified sketches

This has to be “translated” in to an actual Set-up

See e.g. Presentations from the

ECCS TWG 7.5 / ERF-FEM R&S Work Shops

PRACTICAL GUIDE FOR TEST HOUSES USEFUL ???

EN 15 512






ECCS / TC 7.5 & RMI



EN 15 512


ECCS TWG 7.5 / ERF - FEM R&S

• Science

• Checking Engineers / Third Party Experts

• Industry

A platform also for harmonization

Documents

2011-10-07_Hand Out_Ithaca_Harm. of Interpr. en 15512