1.0 TENSION
1.1 Bond Failure Mode
Results ϕ bond
Results ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering
ϕ bond
17.5 . 2 For each applicable factored load combination , design strength of anchors shall satisfy the criteria in Table 17.5.2 .
Table 17.5.2 — Design strength requirements of anchors
Failure Mode Single Anchor
Individual anchor in a Group
Steel strength in tension ( 17.6.1 ) ϕN sa ≥ N ua ϕN sa
≥ N ua , i
Concrete breakout strength in tension ( 17.6 . 2 ) ϕN cb
≥ N ua
Pullout strength in tension ( 17.6.3 ) ϕN pn ≥ N ua ϕN pn
≥ N ua , i
Concrete side-face blowout strength in tension ( 17.6.4 )
Bond strength of adhesive anchor in tension ( 17.6.5 ) ϕN sb
≥ N ua
ϕN a
≥ N ua
Anchor Group
Anchors as a group
ϕN cbg
≥ N ua , g
ϕN sbg
≥ N ua , g
ϕN ag
≥ N ua , g
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 :
…………………………………………….
( e ) 0.75 ϕN a or 0.75 ϕN ag
[ ϕN a or ϕN ag correspond to bond failure ( tension ) in Table 17.5.2 ]
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 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 .
ACI 318-19 strength design provisions for bond failure in tension require calculation of a nominal bond strength ( N a or N ag
). The nominal strength is multiplied by one or more strength reduction factors ( ϕ – factors ) to obtain a design strength ( ϕN a or ϕN ag
). ϕ – factors are relevant to static and seismic load conditions . PROFIS Engineering designates the ϕ – factor corresponding to bond failure for static load conditions “ ϕ bond
”.
Adhesive anchor systems can be qualified for recognition under the International Building Code via testing per the ICC-ES acceptance criteria AC308 in conjunction with the ACI standard ACI 355.4 . PROFIS Engineering uses the ϕ – factors derived from AC308 / ACI 355.4 testing , as given in the ICC-ES evaluation report ( ESR ) for the adhesive anchor system , to calculate design bond strength ( ϕN a or ϕN ag
). These ϕ – factors are relevant to the condition of the concrete in the drilled hole into which the adhesive and anchor element are inserted . Possible drilled hole installation conditions include dry , water saturated , water filled , and underwater ( submerged ). Reference the ESR for ϕ – factors that are specific to these conditions . PROFIS Engineering uses the ϕ – factor corresponding to the drilled hole condition that has been selected to calculate ϕN a or ϕN ag , and designates this parameter “ ϕ bond
” in the Results section of the report .
PROFIS Engineering designates the 0.75 reduction factor noted in ACI 318-19 Section 17.10.5.4 for seismic load conditions “ ϕ seismic
”.
The provisions given in ACI 318-19 Section 17.5.2.2 are used to calculate a bond strength ( 0.55 ϕN ba
) for a single anchor , which is checked against the highest factored sustained tension load ( N ua , s
) determined to be acting on a single anchor within the anchorage . Equations , variables , calculations and results relevant to this sustained load check are given in the PROFIS Engineering report section titled Sustained Tension Load Bond Strength . PROFIS Engineering uses the ϕ – factor corresponding to the drilled hole condition that has been selected ( dry , water saturated , water filled , submerged ) to calculate 0.55 ϕN ba and designates this parameter “ ϕ bond
” in the Results section of the Sustained Tension Load Bond Strength section of the report .
Reference the Calculations section of the PROFIS Engineering Bond Strength section of the report for more information on :
N ba
: basic bond strength
Reference the Results section of the PROFIS Engineering Bond Strength section of the report for more information on the following parameters :
N a or N ag : nominal bond strength ϕN a or ϕN ag
: design bond strength
ϕ seismic
: strength reduction factor for seismic tension
Reference the PROFIS Engineering report section titled Sustained Tension Load Bond Strength for more information about the sustained load check referenced in Section 17.5.2.2 .
43 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions