This document summarizes lessons learned from full-scale loading tests on industrial fiber concrete floors. Design by testing according to Eurocodes allows including unknown beneficial effects but has disadvantages like difficulties performing a sufficient number of tests and risk of major cracks. Loading tests in Sweden combined a test at a suitable location with coring a large number of cores to estimate properties. While loading tests cannot be the sole design method due to challenges, combinations with coring show promise as an alternative quality assurance approach. Further research is needed on hidden factors that influence load-carrying capacity.

1. Aug. 17, 2022 J Silfwerbrand, KTH 1 (12)
Design by Testing –
Lessons Learned from Full-Scale Loading Tests
on Industrial Fibre Concrete Floors
Johan Silfwerbrand
KTH Royal Institute of Technology, Stockholm
24th NCR Symposium, Stockholm, Aug. 17, 2022

2. Outline
 Design by testing according to Eurocodes
 Industrial fibre concrete floors – types & design
methods
 Problems & possible solutions
 Lessons learned
 Concluding remarks
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3. Design by Testing according
to Eurocodes
 Mentioned in EC 2 & described in EC “0”, Annex D
 Design by testing may be used…
 (i) if suitable design models are missing,
 (ii) if large number of similar components are
going to be used or
 (iii) to confirm design assumptions.
 The design by testing should fulfil required safety
level.
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4. Industrial Concrete Floors
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5. Design of Industrial Fibre
Concrete Floors
 Slabs-on-grade are ≠ load-carrying structure 
not dealt by Euro- or most other design codes
 Pile-supported slabs: Is it considered load-
carrying or not?  Different design methods give
very different results.
 Conservative design leads to too thick and
uneconomical FC slabs.
 Less conservative design leads often to slabs that
perform well. But why? Are there neglected
factors that contribute to the load-carrying
capacity?
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6. Possible Benefical Effects
Factor
1. Arch action
2. Membrane effect
3. Load redistribution
4. Contribution from the ground
between the piles
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F
6 (12)

7. Design by Testing
Advantages Disadvantages
Straight-forward way to include
unknown beneficial effects
Difficulties & costs to perform a
sufficiently large number of tests
Possibility to evaluate which
design method that is best
Major cracks & damages (not
desired by the client)
Increased knowledge on the real
performance
Difficulties to create the
necessary ultimate load
Aug. 17, 2022 J Silfwerbrand, KTH
40 kN/m2 =
4,1 m
2 m
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8. Basic Factors Influencing
Load-Carrying Capacity
 Slab thickness
 Concrete strength
 Fibre content
 Fibre distribution & fibre orientation in the
thickness direction
 Contact with & stiffness of underlying grade
 Pile spacing
 Pile characteristics (size of pile head, load-carrying
capacity)
 Horizontal restraint (due to friction or any rigid or semi-
rigid support)
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9. Which Slab Part Should be
Loaded?
A. Interior part between pile heads – positive
moment
B. Interior part above pile head – negative moment
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10. The Swedish Experience
 The real industrial floor cannot
be tested in ULS.
 Tests on SLS are possible.
 Make at least one test at a
suitable location.
 Combine it with a relatively
large number of cores.
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11. Coring
 Large number of cores for
estimating mean value &
scatter of slab thickness,
concrete strength, fibre
content, fibre distribution &
any contact with the
underlying ground.
Aug. 17, 2022 J Silfwerbrand, KTH
h = ?
Any contact?
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12. Concluding Remarks
 Loading tests on fibre concrete industrial floors
may constitute a part of the quality assurance.
 Due to problems with load levels, number of tests
& damage costs, they cannot be the sole method.
 Combinations with coring is a promising
alternative.
 Research on hidden & unquantified factors is
urgent.
Aug. 17, 2022 J Silfwerbrand, KTH 12 (12)