The software gives a maximum possible anchor embedment depth h ef based on the slab thickness. If I use a chemical anchor on metal deck slab, can I disregard this requirement and use h ef up to approximately 10 mm from the metal deck. It is assumed that unlikely the mechanical anchors, the chemical anchors do not develop a compression area at the bottom of the anchor, while the presence of metal deck slab allows us to reduce the concrete cover.
Thank you for your question. Currently there is no design approach within Europe for post installed fixings into composite metal decks. The minimum slab thickness is assessed through two types of tests:
· Minimal edge distance and spacing.
o The purpose of this test to check if there is any failure during installation process under the condition of Cmin, Smin and hmin, which is the most critical case.
· Edge distance to prevent splitting under load.
o The main purpose is to check the Ccr,sp and Scr,sp, which are used for calculating resistance of splitting failure mode. Splitting failure mode is directly influenced by slab thickness, minimal slab thickness is required to be used during the test to represent the most critical case. Your described scenario would have an unknown affect
If translated those two messages into design, thin concrete slab thickness means the possibility of failure during installation and splitting failure below the theoretical value calculated with Ccr,sp and Scr,sp stated in the products ETA.
Having said that as mentioned in absence of a design approach you can only carry out onsite testing to establish the allowable resistances by preliminary of destructive testing, BS8539:2012 would be a document that we would refer you too regarding this aspect.