Epoxy Anchorage - Bond Strength in accordance with ACI 318-14 Section 17.4.5

[rlflower]

This is a technical question regarding the 318-14 Building Code Section 17.4.5: The equations for bond strength in tension appear to have a "glitch". The tensile capacity should be a function of the effective length of the bond. However, the critical edge distance is also a function of the bond length; this critical edge distance ends up in the denominator of a ratio, causing the bond length to "cancel out" of the equation. So, you see, I am up a creek without a paddle.

FYI: I have tried to contact ACI regarding this; however, they require membership for this inquiry.

Please respond ASAP as I have a client waiting! Thank you.

Richard L. Flower, P. E., LEED Green Associate
Senior Structural Engineer
Complere Engineering Group, Inc.

 

[Ingenuity]

The basic bond strength of a single anchor, N_ba = λ_a τ_cr Π d_a h_ef ==> dependent on h_ef

The edge effects are taken care of with the ψ_ed,Na factor, and that will range between 0.7 and 1.0; based upon ψ_ed,Na = 0.7 + 0.3 (c_amin/c_Na); with c_Na dependent on the anchor diameter, d_a.

The nominal bond strength in tension is N_a = ψ_ed,Na N_ba (neglecting cracked/uncracked concrete factor ψ_cp,Na). This is direct multiplication of factor/s x capacity.

I don't see where the effective embedment depth h_ef cancel out.