2.0 SHEAR
2.4 Stand-off Failure Mode
Results ϕ nonductile
Results ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering
ϕ nonductile
ACI 318-19 Section 17.10.6.3 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 Ω 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
Steel strength in shear |
|
|
( 17.7.1 ) |
ϕV sa
≥ V ua
|
ϕV sa
≥ V ua , i
|
Anchor Group
Anchors as a group
ACI 318-19 strength design provisions for steel failure in shear require calculation of a nominal steel strength ( V sa
). The nominal strength is multiplied by a strength reduction factor ( ϕ-factor ) to obtain a design strength ( ϕV sa
). Unlike the provisions given in ACI 318-19 Section 17.10.5.4 for seismic tension loading , which require an additional 0.75 reduction factor to be applied to non-steel tension design strengths ; ACI 318-19 anchoring-to-concrete provisions for shear loading do not require this 0.75 reduction factor to be applied to any shear design strength when designing an anchorage subject to seismic loading in shear .
The parameter “ ϕ nonductile
” is a reduction factor for seismic load conditions that is given in Part D . 3.3.6 of the anchoring-to-concrete provisions in ACI 318-08 Appendix D . This reduction factor can range from a value of 0.4 to 1.0 , depending on the application , and PROFIS Engineering designates this factor “ ϕ nonductile
”.
“ ϕ nonductile
” is not a relevant parameter for seismic design per ACI 318-19 Chapter 17 ; therefore , it is always referenced in the PROFIS Engineering report for ACI 318- 19 calculations as equal to 1.0 .
Reference the PROFIS Engineering Design Guide for ACI 318-08 anchoring-toconcrete provisions for more information on ϕ nonductile
.
Concrete breakout strength 11 shear ( 17.7.2 )
Concrete pryout strength in shear ( 17.7.3 ) ϕV cb
≥ V ua
ϕV cp
≥ V ua ϕV cbg
≥ V ua , g
ϕV cpg
≥ V ua , g
ACI 318-08 Part D . 3.3.6 D . 3.3.6 — As an alternative to D . 3.3.4 and D . 3.3.5 , it shall be permitted to take the design strength of the anchors as 0.4 times the design strength determined in accordance with D . 3.3.3 . For the anchors of stud bearing walls , it shall be permitted to take the design strength of the anchors as 0.5 times the design strength determined in accordance with D . 3.3.3 .
303 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions