At Hilti, we’re passionate about the products we develop and helping all our customers to make the right choices for their projects. Here are just some of the topics we’ve recently given feedback upon, to customers across a range of applications and materials.

Q. Demountable screen fixing to 150mm metal deck

I have a 150mm metal deck floor with 90mm of concrete above the deck. According to previous comments I have tried to use a HST3 anchor but the screen I'm fixing is 1.9m tall with crowd loading and needs to be demount-able. Is it possible to use a HKD socket anchor, I can't find this in the PROFIS software I'm using?

Thank you for your question, the HKD and HSC-I internally threaded sockets are both contained within the PROFIS Engineering software. The base material thickness of 90 mm however is below the minimum thickness requirements for these products, so they will not be an active option. In addition, the HKD is not approved for single point fixing within areas of concrete that is deemed to be in tension/cracked. However, you are at liberty to undertake your own site testing and make an Engineering Judgement based upon the conditions ‘as found’. We would refer you to BS8539:2012 for further information should you wish to pursue that option.

 
Q. Chemical Hilti anchor on metal deck slab - hef based on slab thickness

The software gives a maximum possible anchor embedment depth hef based on the slab thickness. If I use a chemical anchor on metal deck slab, can I disregard this requirement and use hef up to approximately 10 mm from the metal deck? It is assumed that unlike 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 - The purpose of this test to check if there is any failure during the installation process under the condition of Cmin, Smin and hmin, which is the most critical case.

Edge distance to prevent splitting under load - 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, while minimal slab thickness is required to be used during the test to represent the most critical case. Your described scenario would have an unknown effect. 

If translating 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. In the 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 to regarding this aspect.

Q. Fixings into composite concrete decking

What kind of fixings into holorib type decking due to reduced concrete depth where troughs do not occur can be used.
 
Thank you for your question. The minimum thickness of concrete that we have published data available for is 80mm for installations utilising the HST3 M8 or M10 mechanical stud anchors. Additionally, depending upon the application, it is also possible to utilise our Powder Actuated Fasteners to 80mm thick concrete. The technical data for these product ranges can be found on our website.

Q. Chemical anchors such as Hit HY 270 and Hit HY 170, what is the design life of these fastenings?

What is the design life of these chemical fixings?
 
The ETA (European technical assessment) approval of anchors specifies "a working life of the anchor of at least 50 years". please find links to the ETA's for the two resins under technical documentation – for the HY270 here and HY170 here.

Q. Anchor on grouted baseplate design – failure in shear

I’m carrying out an anchor design on a baseplate with a 25mm grout standoff, but I'm getting a failure on the anchors in shear. If I remove the standoff the utilisation is only 20%. Please could you help me with this?
 
Thank you for your question. Calculation with the use of standoff will lower the steel capacity significatively according to code. There are two changes that will help with this. Using a higher steel grade and/or using a larger diameter of anchor rod.

Q. Suitable anchors for fixing into natural stones

We are currently working on a project which requires anchors to fix a steel structure into natural stone wall at multiple points. The stone type is unknown at time of writing (possibly sandstone).
What would be the most suitable anchor and resin type to use for this? And is there any technical data available for anchoring into stonework?
 
Thank you for your enquiry regarding HILTI products and their use in a potential sandstone base material. Whilst we have no specific data, typically anchorages into masonry have tended to be the resin installed system such as the HIT-HY270 injection mortar. This product is utilised with masonry and blockwork structures (Solid or hollow) and can be utilised for external and internal applications. We would also, in accordance with BS8539:2012, recommend onsite testing to establish load resistances in the absence of published data.

Q. Are Hilti's resins suitable for thermalite blocks?

I'm currently working on a project that requires eventual resins fixing in thermalite block. Is it ok to use Hilti resins on this specific type of blocks? If so, what type of resin do you recommend, how much is the maximum pull-out and shear resistance, recommended type of bolt, and also the minimum embedment depth. Thanks in advance.

Thank you for your question. Please follow the link to our Anchor Fastening Technical Manual.
Please go the chapter covering chemical anchors for masonry / HIT-HY 270 injection mortar. You will find tables for many different base materials that are not solid normal concrete. Unfortunately, the Thermalite blocks you are referring to, are not available here. But it could be that the SLWC1 – Solid Light Weight Concrete Brick 1 or SLWC2 (page 280 and 290) would be the most similar. Hilti HIT-HY 270 in combination with a HIT-V anchor rod of appropriate size and material would be the product to use. We would also, in accordance with BS8539:2012, recommend onsite testing to establish load resistances in the absence of published data.
 
If you have any technical queries or a project you need some support on then why not ask us a question now.