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Bond Strength of rebars in uncracked concrete with supplementary reinforcement

Posted by Sayantani Dutta10 months ago
Bond Strength of rebars in uncracked concrete with supplementary reinforcement

Hi
Why does Hilti Profis not use 1.0 for bond splitting factor for post-installed rebars (adhesive anchor) in tension when there is supplemental reinforcement in uncracked concrete ? The equations 17.6.5.5.1a & 17.6.5.5.1b in ACI 318-19 are only for uncracked concrete without supplementary reinforcement. This often causes the bond strength in cracked concrete to be higher than uncracked concrete.

uncracked,Cracked,bond strength,bond splitting factor
Software & Services file 0
Hilti Profis Rebar tension uncracked.pdf350.27 KB
2 Replies
Posted by Sinan Beskok10 months ago
Hilti Verified

Hi Sayantani,

Thank you for reaching out. Could you please send this question along with your PROFIS Engineering .pe file to hnatechnicalservices@hilti.com? They will be able to look into your file and provide input there.

Kind regards,
Sinan

uncracked,Cracked,profis engineering,Bond Splitting
Posted by Leighton11 days ago

Was there a resolution to this inquiry? The "supplementary reinforcement" section of user input does not appear to have an explicit "splitting supplementary reinforcement" check box (only shear and tension supplementary reinforcement). So when uncracked concrete is used, psi_cp,N can result in a value much lower than 1, even if the designer provides splitting reinforcement.

Supplementary,splitting,reinforcement
1 comment on this reply
Posted by Sayantani Dutta11 days ago
The essence of what i was told is this ''Hilti PROFIS Engineering does not apply a bond splitting factor = 1.0 for post-installed rebar in uncracked concrete, even when supplementary reinforcement is present, because ACI 318-19 does not clearly define how supplementary reinforcement should be considered for splitting failure. PROFIS Engineering uses a strict interpretation of the design code. The ICC-ES acceptance criteria are set up in such a way that if post-installed anchors are tested in uncracked concrete, splitting failure is possible. Furthermore, minimal reinforcement is present in the concrete during this testing. The concrete is considered to be essentially unreinforced, although there must be a limited amount of reinforcement to construct the test slab/block. If tested in cracked concrete, splitting failure is precluded because reinforcement to control cracking is present. Refer https://viewer.joomag.com/profis-design-guide-ac-318-19-july-2022/0546853001659024142/p77?''