PROFIS Design Guide - AC 318-19 July 2022 | Page 305

2.4 Stand-off Failure Mode

Results фV _{sa , eq}

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

фV _{sa , eq}

17.10.6.3 Anchors and their attachments shall satisfy ( a ), ( b ) or ( c ).

( a ) Anchor or anchor groups shall be designed for the maximum shear that can be transmitted to the anchor or anchor groups based on the development of a ductile yield mechanism in the attachment in tension , flexure , shear , or bearing , or a combination of those conditions , and considering both material overstrength and strain hardening effects in the attachment .

( b ) Anchor or anchor groups shall be designed for the maximum shear that can be transmitted to the anchors by a non-yielding attachment .

( c ) Anchor or anchor groups shall be designed for the maximum shear obtained from factored load combinations that include E , with E _h increased by ф ₀

.

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 ( фV _N

) against a factored shear load ( V _ua

). 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 ф-factor for steel failure . If the anchorage design is based on seismic load conditions , PROFIS Engineering desig-nates “ V _sa

” as “ V _{sa , eq} ” because V _sa

-values for some postinstalled anchors in the PROFIS Engineering portfolio are specific to seismic loading .

For applications consisting of only one anchor in shear , the design strength ( фV _{sa , eq}

) is checked against the shear load acting on that anchor ( V _ua ). If an application consists of a group of anchors in shear , V _{sa , eq} is calculated for a single anchor , and the design strength ( фV _{sa , eq} ) is checked against the highest individual loaded anchor in shear ( V _{ua , i}

). 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

ф _steel

. ACI 318-08 anchoring-to-concrete provisions include an additional seismic reduction factor corresponding to brittle failure modes . Design steel strengths calculated for a brittle steel anchor element using ACI 318-08 seismic provisions include an additional strength reduction factor , which PROFIS Engineering designates “ ф _nonductile

”. Since ф _nonductile is only relevant to seismic calcu-lations with ACI 318-08 provisions , PROFIS Engineering shows “ ф _nonductile

” equal to 1.0 in the

Results section of reports for ACI 318-19 provisions .

When modeling an anchor element in PROFIS Engineering for a grouted standoff , an additional reduction factor (= 0.80 ) is applied to the nominal steel strength per Section 17.7.1.2.1 . PROFIS Engineering designates this parameter “ ф _eb

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

V _{sa , eq}

.

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

ф _steel

: strength reduction factor for steel failure

ф _eb

: strength reduction factor for grouted stand-offs

ф _nonductile

: seismic strength reduction factor

фV _{sa , eq}

: nominal steel strength in shear ( seismic 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 .

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