PROFIS Design Guide - AC 318-19 July 2022 | Page 152

1.6 Sustained Load Failure Mode

Equations ϕN _ba

Equations ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering 0.55 ϕN _ba

≥ ^N ua , s

17.5.2.2 Design of adhesive anchors to resist sustained tension shall satisfy Eq . ( 17.5.2.2 ) 0.55 ϕN _ba

≥ ^N ua , s ^{( 17 . 5 . 2 . 2 )} where N _ba is the basic bond strength in tension of a single adhesive anchor and is N _{ua , s} the factored sustained tensile load .

17.6.5 . 2.1 Basic bond strength of a single adhesive anchor in tension in cracked concrete , N _ba , shall be calculated by Eq . ( 17.6.5.2.1 )

N _ba

= λ _a т _cr π _da h _ef

( 17.6.5.2.1 )

PROFIS Engineering parameters for calculating N _ba :

N _ba

= λ _a т _{k , c} α _{N , seis} πd _a h _ef

PROFIS Engineering calculations for N _ba when used to calculate the sustained load parameter

0.55 ϕN _ba for threaded rods , reinforcing bars and HIS-N and HIS-RN inserts :

N _ba

=

( λ _a т _xxxx α _{N , seis} πd _a h _ef

) α _{N , seis}

PROFIS Engineering calculations for N _ba when used to calculate the sustained load parameter

0.55 ϕN _ba : for HIT-HY 200 used with HIT-Z and HIT-Z-R threaded rods :

The provisions given in ACI 318-19 Section 17.5.2.2 are used to perform a check for adhesive anchors subjected to sustained tension loads . The check consists of calculating a capacity ( 0.55ϕN _ba

), and comparing it to the highest ( factored ) sustained tension load ( N _{ua , s}

) acting on a single anchor within the anchor group . The strength reduction factor ( ϕ-factor ) in Eq . ( 17.5.2.2 ) corresponds to the parameter “ ϕ _bond

” in the PROFIS Engineering report . The parameter “ N _ba

” corresponds to the “ basic bond strength ” for a single adhesive anchor without any fixed edge influences . N _ba is calculated per Eq . ( 17.6.5.2.1 ); but an additional seismic modification factor that is derived from testing per the ICC-ES acceptance criteria AC308 is not given in Eq . ( 17.6.5.2.1 ), and must also be considered in the N _ba

-calculation . This seismic modification factor is designated “ α _{N , seis} ”, and is included in PROFIS Engineering

N _ba

-calculations when seismic conditions are being modeled . However , since seismic load is not considered a sustained load , PROFIS Engineering divides out any α _{N , seis}

-value when calculating N _ba per Eq . ( 17.6.5.2.1 ).

Reference the Equations , Calculations and Results section of the report for more information on :

N _ba

: basic bond strength parameters and calculations for the sustained tension load check

Reference the Design Guide sections about pullout for more information about the HIT-HY 200 / HIT-Z parameter N _p

.

152 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions