PART 4 SHEAR LOAD
Steel Failure Mode
Results ϕ nonductile
Results 318-14 Chapter 17 Provision Comments for PROFIS Engineering
ϕ nonductile
ACI 318-14 Section 17.2.3.5.3 17.2.3.5.3 Anchors and their attachments shall be designed using one of options ( a ) through ( c ):
( a ) The anchor or group of anchors shall be designed for the maximum shear that can be transmitted to the anchor or group of anchors based on the development of a ductile yield mechanism in the attachment in flexure , shear , or bearing , or a combination of those conditions , and considering both material overstrength and strain hardening effects in the attachment .
( b ) The anchor or group of anchors shall be designed for the maximum shear that can be transmitted to the anchors by a non-yielding attachment .
( c ) The anchor or group of anchors shall be designed for the maximum shear obtained from design load combinations that include E , with E increased by Ω 0
. The anchor design shear strength shall satisfy the shear strength requirements of 17.3.1.1 .
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 .
Excerpt from ACI 318-14 Table 17.3.1.1 showing provisions for shear calculations .
ACI 318-14 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 318-14 Section 17.2.3.4.4 for seismic tension loading , which require an additional 0.75 reduction factor to be applied to non-steel tension design strengths ; ACI 318-14 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 318-14 Chapter 17 ; therefore , it is always referenced in the PROFIS Engineering report for ACI 318- 14 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
.
Table 17.3.1.1 — Required strength of anchors , except as noted in 17.2.3
Failure Mode
Steel strength in shear ( 17.5.1 )
Concrete breakout strength in shear ( 17.5 . 2 )
Concrete pryout strength in shear ( 17.5.3 )
Single Anchor
ϕ steel
V sa
≥ V ua ϕ concrete
V cb
≥ V ua ϕ concrete
V cp
≥ V ua
Individual anchor in a group
ϕ steel
V sa
≥ V ua , i
Anchor Group
Anchors as a group
ϕ concrete
V cbg
≥ V ua , g ϕ concrete
V cng
≥ 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 .
313 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions