PART 3 TENSION LOAD
Pullout Failure Mode
Equations ϕN pn
Equations ACI 318-14 Chapter 17 Provision Comments for PROFIS Engineering
ϕN pn
≥ N ua
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 Failure Mode
Single Anchor Individual Anchor in a Group
Pullout Strength in Tension ϕN pn ≥ N ua ϕN pn
> N ua , i
Below is a summary of PROFIS Engineering pullout strength calculations . For a single anchor in tension , PROFIS Engineering checks the calculated design strength against the factored tension load acting on that anchor ( N ua
). For a group of anchors in tension , PROFIS Engineering checks the calculated design strength against the highest factored tension load determined to be acting on a single anchor ( N ua
). cast-in anchors PROFIS Engineering parameters for calculating the nominal pullout strength of cast-in anchors :
N pn
= ψ c , p
N p
( 17.4.3.1 )
PROFIS Engineering parameters for calculating the design pullout strength of cast-in anchors : static load conditions — design strength = ϕ concrete
N pn seismic load conditions — design strength = ϕ seismic ϕ concrete
N pn mechanical anchors PROFIS Engineering parameters for calculating the nominal pullout strength of mechanical anchors :
N pn , f ́c
= N p , 2500 λ a
( f ́c / 2500 ) n
PROFIS Engineering parameters for calculating the design pullout strength of mechanical anchors : static load conditions — design strength = ϕ concrete
N pn , f ́c seismic load conditions — design strength = ϕ seismic ϕ concrete
N pn , f ́c
HIT-Z / R threaded rods used with HIT-HY 200 adhesive PROFIS Engineering parameters for calculating the nominal pullout strength of HIT-Z and HIT-Z-R threaded rods used with HIT-HY 200 adhesive :
N pn
= N p λ a
PROFIS Engineering parameters for calculating the design pullout strength of HIT-Z and HIT-Z-R anchors used with HIT-HY 200 adhesive : static load conditions — design strength = ϕ concrete
N pn seismic load conditions — design strength = ϕ seismic ϕ concrete
N pn
ACI 318-14 strength design provisions for tension check a calculated design strength ( ϕN N
) against a factored tension load ( N ua
). The parameter “ design strength ” is defined as the product of a “ nominal strength ” ( N N
) and one or more strength reduction factors ( ϕ-factors ). If ϕN N > N ua for all relevant tension failure modes , the ACI 318-14 tension provisions are satisfied .
Nominal pullout strength in tension ( N pn
) is always calculated for a single anchor when designing with the provisions of ACI 318-14 . If an application consists of a group of anchors in tension , N pn is calculated for a single anchor , and the design strength is checked against the highest loaded anchor in tension .
Since pullout failure can be considered a “ concrete ” failure mode , PROFIS Engineering designates the strength reduction factor for pullout failure “ ϕ concrete
”. ACI 318-14 anchoring-to-concrete provisions for seismic load conditions require an additional ϕ-factor to be applied to non-steel design strengths . PROFIS Engineering designates this parameter “ ϕ seismic
”.
ACI 318-08 anchoring-to-concrete provisions include an additional seismic reduction factor that is applied to anchor design strengths corresponding to brittle failure modes . Pullout failure is considered a brittle failure mode ; therefore , design pullout strengths calculated using ACI 318-08 seismic provisions would include an additional strength reduction factor , which PROFIS Engineering designates “ ϕ nonductile
”. Since ϕ nonductile is only relevant to seismic calculations with ACI 318-08 provisions , PROFIS Engineering always shows the parameter “ ϕ nonductile
” equal to
1.0 in the Results section of reports for ACI 318-14 provisions .
Reference the Equations and Results section of the PROFIS Engineering report for more information on :
N pn or N pn , f ’ c :
Nominal pullout strength in tension
Reference the Results section of the PROFIS Engineering report for more information on the following parameters :
ϕ concrete
:
ϕ seismic
:
Strength reduction factor for pullout failure Strength reduction factor for seismic tension ϕN pn or ϕN pn , f ́c : Design steel strength in tension
N ua
:
Factored load acting on anchors in tension
A summary of calculated tension design strength versus the factored tension load for each tension failure mode relevant to the application is given in Part 3 Tension Load of the PROFIS Engineering report .
83 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions