PROFIS Design Guide - AC 318-19 July 2022 | Page 304

2.4 Stand-off Failure Mode

Results ϕV _sa

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

ϕV _sa

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

Excerpt from ACI 318-19 Table 17.5.2 showing provisions for shear calculations .

Table 17.5.2 — Design strength requirements of anchors

Failure Mode Single Anchor

Individual anchor in a Group

Concrete breakout strength 11 shear ( 17.7.2 )

Concrete pryout strength in shear ( 17.7.3 ) ϕV _cb

≥ V _ua

ϕV _cp

≥ V _ua

Anchor Group

Anchors as a group

ϕV _cbg

≥ V _{ua , g}

ϕV _cpg

≥ V _{ua , g}

ACI 318-19 strength design provisions for anchors in 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 . When designing with ACI 318-19 anchoring-to-concrete provisions , nominal steel strength in shear ( V _sa

) is always calculated for a single anchor , and multiplied by the ϕ-factor for steel failure .

For applications consisting of only one anchor in shear , the design strength ( ϕV _sa ) is checked against the shear load acting on that anchor ( V _ua ). If ϕV _sa

≥ ^V , the ACI ua

318-19 provisions for steel failure in shear are satisfied . If an application consists of a group of anchors in shear , V _sa is calculated for a single anchor , and the design strength ( ϕV _sa ) is checked against the highest individual loaded anchor in shear ( V _{ua , i} ). If ϕV _sa

≥ V _{ua , i}

, the ACI 318-19 provisions for steel failure in shear are satisfied . The PROFIS Engineering report section for steel failure in shear uses the generic designation “ V _ua

” to reference either the only shear load acting on an anchor in shear , or the highest shear load acting on an individual anchor within an anchor group in shear .

PROFIS Engineering designates the strength reduction factor for steel failure

ϕ _steel

. When modeling an anchor element in PROFIS Engineering using ACI 318-19 provisions , the calculated design steel strength in shear for static load conditions equals ϕ _steel

V _sa

; however , if a grouted standoff is being modeled , an additional reduction factor (= 0.80 ) is applied to the nominal steel strength per Section 17.7.1.2.1 . PROFIS Engineering designates this reduction factor “ ϕ _eb

” and shows it in the Results section of the report . The calculated design steel strength in shear for static load conditions and a grouted stand-off equals ϕ _steel ϕ _eb

V _sa

Reference the Equations section of the PROFIS Engineering report for more information on :

ϕV _sa

: design 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

ϕ _eb

: strength reduction factor for grouted standoffs

ϕV _sa

: nominal steel strength in shear ( static load conditions )

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 .

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