PROFIS Design Guide - AC 318-19 July 2022 | Page 289

2.4 Stand-off Failure Mode

Equations ϕ _steel

≥ V _ua

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

ϕ _steel

≥ V _ua

17.5 . 2 For each applicable factored load combination , design strength of anchors shall satisfy the criteria in Table 17.5.2 .

ACI 318-19 strength design provisions for shear check a calculated design strength ( ϕV _N

) against a factored shear load ( V _ua

). The parameter “ design strength ” is defined as the product of a “ nominal strength ” ( V _N

) and one or more strength reduction factors ( ϕ-factors ). If ϕV _N ≥ V _ua for all relevant shear failure modes , the

ACI 318-19 shear provisions are satisfied . Nominal steel strength in shear ( V _sa

) is always calculated for a single anchor when designing with the provisions of ACI 318-19 . If an application consists of a group of anchors in shear , V _sa is calculated for a single anchor , and the design strength is checked against the highest loaded anchor in shear .

PROFIS Engineering designates the strength reduction factor for steel failure

ϕ _steel

. ACI 318-08 anchoring-to-concrete provisions include an additional seismic reduction factor that is used to calculate anchor design strengths corresponding to brittle failure modes . Anchor elements can be defined in ACI 318 as “ ductile ” or “ brittle ” steel elements . Steel failure for a brittle steel anchor element is a “ brittle ”, i . e . “ nonductile ” failure mode ; therefore , design steel strength calculated for a brittle steel anchor element using ACI 318-08 seismic provisions includes an additional strength reduction factor . PROFIS Engineering designates this seismic reduction factor “ ϕ _nonductile

”, and shows it in the results section of the report .

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 318-19 provisions .

When modeling an anchor element subject to shear loads using ACI 318-19 provisions , PROFIS Engineering calculates design steel strength for static load conditions as “ ϕ _steel

V _sa

”, and the design steel strength for seismic load conditions as “ ϕ _steel

V _{sa , eq}

”. Reference the Calculations and Results section of the PROFIS Engineering report for information on :

V _sa

: nominal ( static ) steel strength in shear .

V _{sa , eq}

: nominal ( seismic ) steel strength in shear .

Reference the Results section of the PROFIS Engineering report for more information on the following parameters :

ϕ _steel

: strength reduction factor for steel failure

ϕV _sa

: design ( static ) steel strength in shear

ϕV _{sa , eq}

: design ( seismic ) steel strength in shear

V _ua

: factored load acting on anchors in shear

A summary of calculated shear design strength versus the factored shear load for each shear failure mode relevant to the application is given in Part 4 Shear Load of the PROFIS Engineering report .

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