1.0 TENSION
1.2 Concrete Breakout Failure Mode
Results ϕ seismic
Results ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering
ϕ seismic
17.10.5.4 The anchor design tensile strength shall be calculated from ( a ) through ( e ) for the failure modes given in Table 17.5.2 assuming the concrete is cracked unless it can be demonstrated that the concrete remains uncracked :
( a ) ϕN sa for a single anchor or for the most highly stressed individual anchor in an anchor group [ ϕN sa corresponds to steel failure ( tension ) in Table 17.5.2 ] ( b ) 0.75ϕN cb or 0.75ϕN cbg except that N cb or N cbg need not be calculated if anchor reinforcement satisfying 17.5.2.1 ( a ) is provided [ ϕN cb or ϕN cbg correspond to concrete breakout failure ( tension ) in Table 17.5.2 ]
( c ) 0.75ϕN pn for a single anchor or for the most highly stressed individual anchor in an anchor group [ ϕN pn corresponds to pullout failure ( tension ) in Table 17.5.2 ] ( d ) 0.75ϕN sb or 0.75ϕN sbg
[ ϕN sb or ϕN sbg correspond to side-face blowout failure ( tension ) in Table 17.5.2 ]
( e ) 0.75ϕN a or 0.75ϕN ag
[ ϕN a or ϕN ag correspond to bond failure ( tension ) in Table 17.5.2 ]
where ϕ is in accordance with 17.5.3 .
PROFIS Engineering calculations for concrete breakout failure in tension when seismic load conditions are being modeled :
single anchor : design concrete breakout strength = ϕ seismic ϕ concrete
N cb
. anchor group : design concrete breakout strength = ϕ seismic ϕ concrete
N cbg
.
ACI 318-19 strength design provisions for concrete breakout failure in tension require calculation of a nominal concrete breakout strength ( N cb or N cbg
). The nominal strength is multiplied by one or more strength reduction factors ( ϕ-factors ) to obtain a design strength ( ϕN cb or ϕN cbg
). ϕ-factors are relevant to static and seismic load conditions .
PROFIS Engineering designates the 0.75 reduction factor noted in ACI 318-19 Section 17.10.5.4 for seismic load conditions “ ϕ seismic
”. This reduction is applied to non-steel failure modes when calculating tension design strengths for both castin-place and post-installed anchors .
When calculating the design concrete breakout strength in tension for cast-inplace anchors , the parameter “ ϕ concrete
” in the PROFIS Engineering report is taken from Table 17.5.3 ( b ), and corresponds to the parameter “ ϕ ” shown in Section 17.10.5.4 .
When calculating the design concrete breakout strength in tension for postinstalled anchors , the parameter “ ϕ concrete
” in the PROFIS Engineering report corresponding to the parameter “ ϕ ” shown in Section 17.10.5.4 is taken as follows :
• if “ Condition B ” is selected as a design parameter , “ ϕ concrete
” is taken from the ϕ-factor given in the ICC-ES evaluation report ( ESR ) for the anchor .
• if “ Condition A ” is selected as a design parameter , “ ϕ concrete
” is taken from the ϕ-factor in Table 17.5.3 ( b ) corresponding to “ supplementary reinforcement present ”.
Reference the Results section of the PROFIS Engineering report for more information on the following parameters :
N cb or N cbg : nominal concrete breakout strength in tension ϕN cb or ϕN cbg
: design concrete breakout strength in tension
ϕ concrete
: strength reduction factor for concrete failure
78 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions