How can I make sure that my concrete is fully ductile at any point in the structure?
Fibre orientation and particularly fibre distribution are unfortunately not as uniform as everybody wishes. Therefore after having determined the dosage rate at which for a specific fibre, full ductility can be achieved on average, we recommend increasing the given dosage rate by about 20% to make sure that full ductility is reached at any point of the structure. This percentage is based on the fact, that for a normal fibre distribution, the single dosage rate should not deviate more then 20% from the targeted value.
What is the current status of standards regarding structural SFRC applications?
Today, even “historical” applications in SFRC like industrial floors are missing standards in many countries. Therefore it’s no surprise, that for structural applications the situation is even worse. Actually the only country that has a standard for structural SFRC is Austria (OeVBB Richtlinie Faserbeton).
In Germany, the new “DAfStb Richtlinie Stahlfaserbeton” will soon be published as yellow print. Alternatively, the Eurocodes allow designs based on test data and theoretical reflections where issues are not specifically addressed in the code. Structural designs from ArcelorMittal are proprietary designs based on this option.
Can I use any metal decking for constructing a TAB-Deck™ project?
Theoretically all metal decks on the market can be used for TAB-Deck™. However, as TAB-Deck™ takes into consideration the composite action between the steel deck and SFRC, before doing so, it is necessary to conduct a certain number of tests to characterize this composite behaviour. Test results are available today for SMD (UK) metal deck profiles TR60™, TR80™ and R51™ when used in conjunction with HE 1/50 fibres as well as for ARVAL (ArcelorMittal) Cofraplus 60 decks when HE+ 1/60 fibres are used in the SFRC.
Why do I need APC (Anti-Progressive Collapse) rebars in TAB-Slab™ applications?
APC rebars are included to avoid anti-progressive collapse of a structure.
After the events of 11 September 2001, where the floors of the World Trade Center towers collapsed within seconds one after the other, the placement of such rebars became mandatory in North America.
APC rebars are additional rebars, which are not taken into account for the bearing behaviour of the normal RC or SFRC structure. Their only purpose is to prevent the so-called progressive collapse. As ArcelorMittal conducts business worldwide the decision was made to use APC rebars in all TAB-Slab™ structures to avoid differences from country to country with a view to continuity in design and construction.
What about fire safety with TAB-Deck™ and TAB-Slab™ applications?
Regarding TAB-Deck™, fire tests on beam-slab systems have been conducted at Warrington Fire Testing (UK) and at Effectis (F). These are two of the major fire testing facilities in Europe, where fire ratings up to two hours could be achieved.
For TAB-Slab™ it is very difficult and expensive to carry out full-scale tests allowing the deduction of usable design criteria. Therefore heating tests were done with 0, 50 and 100 kg/m³ of steel fibres to analyze the variation of thermal conductivity. During these tests, no such increase of thermal conductivity due to the higher fibre content could be measured and it can be assumed that fibres do not change the behaviour of concrete under fire even at high dosage rates. Therefore regarding fire engineering SFRC can be addressed in the same manner as plain or reinforced concrete.