PROFIS ENGINEERING REPORT TENSION LOAD
Bond Failure Mode
Results ϕ seismic
Results ACI 318-14 Chapter 17 Provision Comments for PROFIS Engineering
ϕ seismic
17.2.3.4.4 The anchor design tensile strength for resisting earthquake forces shall be determined from consideration of ( a ) through ( e ) for the failure modes given in Table 17.3.1.1 assuming the concrete is cracked unless it can be demonstrated that the concrete remains uncracked :
( a ) …………………………. ( b ) 0.75ϕN cb or 0.75ϕN cbg ( c ) …………………………. ( d ) …………………………. ( e ) 0.75ϕN a or 0.75ϕN ag
17.3.1.1 The design of anchors shall be in accordance with Table 17.3.1.1 . In addition , the design of anchors shall satisfy 17.2.3 for earthquake loading and 17.3.1.2 for adhesive anchors subject to sustained tensile loading .
Table 17.3.1.1 — Required strength of anchors , except as noted in 17.2.3
Failure Mode Single Anchor
Individual anchor in a Group
Steel strength in tension ( 17.4.1 ) ϕN sa ≥ N ua ϕN sa
≥ N ua , i
Concrete breakout strength in tension ( 17.4.2 ) ϕN cb
≥ N ua
Pullout strength in tension ( 17.4.3 ) ϕN pn ≥ N ua ϕN pn
≥ N ua , i
Anchor Group
Anchors as a group
ϕN cbg
≥ N ua , g
ACI 318-14 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 .
ACI 318-14 Section 17.2.3.4.4 contains provisions to calculate tension design strengths for seismic load conditions . PROFIS Engineering designates the 0.75 reduction factor noted in this section as “ ϕ seismic
”. This reduction is applied to non-steel tension failure modes . When calculating tension design strengths for adhesive anchors , the relevant non-steel tension failure modes to which this reduction is applied include concrete breakout failure ( 0.75ϕN cb or 0.75ϕN cbg ) and bond failure ( 0.75ϕN a or 0.75ϕN ag
), as referenced in the excerpt to the left .
The ϕ-factors referenced in Table 17.3.1.1 correspond to tension design strengths calculated for static load conditions . The PROFIS Engineering report designates the ϕ-factor corresponding to bond failure for static load conditions “ ϕ bond
”.
PROFIS Engineering uses the ϕ-factors derived from AC308 / ACI 355.4 testing , as given in the ICC-ESR for the adhesive anchor system , for the parameter “ ϕ bond
”.
When seismic load conditions are modeled in PROFIS Engineering for an adhesive anchor system , the software calculates a design bond strength corresponding to ( 0.75 ϕ bond
N a or 0.75 ϕ bond
N ag
).
Reference the Results section of the PROFIS Engineering 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 bond
: Strength reduction factor for concrete failure
Concrete side-face blowout strength in tension ( 17.4.4 )
Bond strengh of adhesive anchor in tension ( 17.4.5 ) ϕN sb
≥ N ua
ϕN a
≥ N ua ϕN sbg
≥ N ua , g
ϕN ag
≥ N ua , g
PROFIS Engineering calculations for bond failure in tension when seismic load conditions are being modeled :
single anchor : design bond strength = ϕ seismic ϕ concrete
N a
. anchor group : design bond strength = ϕ seismic ϕ concrete
N ag
.
45 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions