PART 4 SHEAR LOAD
Stand-off Failure Mode
Variables ϕN ua
Variables 318-14 Chapter 17 Provision Comments for PROFIS Engineering
ϕN ua
5.2.3.2 Steel failure b ) Shear load with lever arm
The characteristic resistance of an anchor , V Rk , s , is given by Equation ( 5.5 ). where
V Rk , s
= α M M Rk , s [ N ] ( 5.5 ) l α M
= see 4.2.2.4 l = lever arm according to Equation ( 4.2 )
M Rk , s
= M 0 ( 1 - N / N ) [ Nm ] ( 5 . 5a )
Rk , s Sd Rd , s
ACI 318-14 Chapter 17 Provision
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 Table 17.3.1.1 showing the tension failure modes considered in ACI 318-14 anchoringto-concrete provisions .
Table 17.3.1.1 — Required strength of anchors , except as noted in 17.2.3
Failure Mode Single Anchor
Individual anchor in a Group
Steel strength in tension ( 17.4.1 ) ϕN sa ≥ N ua ϕN sa
≥ N ua , i
Anchor Group
Anchors as a group
PROFIS Engineering uses the provisions given in the European Technical Approval Guideline ( ETAG ) titled ETAG 001 Metal Anchors for Use in Concrete Annex C : Design Methods for Anchorages to consider bolt bending as a possible shear failure mode . The design criteria for this failure mode consider the highest load acting on an individual anchor , and a design resistance ( strength ) for a single anchor . Bending develops within an anchor element when a shear load acts on a fixture having stand-off . The ETAG 001 parameter “ M Rk , s
” in Equation ( 5.5 ) corresponds to an internal bending moment , which can be defined as a “ characteristic bending resistance for steel failure ”. M Rk , s is calculated for a single anchor using the material properties of the anchor . If both tension and shear loads act on the anchor , M Rk , s must be reduced by a factor ( 1 - N Sd / N Rd , s
) per Equation ( 5.5a ) to account for the combined anchor loading . The parameter “ N Sd
” corresponds to the highest “ design steel tensile load ” acting on the anchor , and the parameter “ N Rd , s
” corresponds to the “ design steel tension resistance ” for the anchor . PROFIS Engineering uses the following nomenclature to define ETAG 001 Equations ( 5.5 ) and ( 5.5a ):
where ϕV M s = ϕ ( α M M s )/ L b modified ETAG 001 Equation ( 5 . 5 )
M s
= M 0 ( 1 - N / ϕN ) modified ETAG 001 Equation ( 5 . 5a ) s ua sa
V M = nominal shear strength ( resistance ) s ϕV M = shear design bending strength ( resistance ) of the anchor s
M s
= resultant flexural strength ( resistance ) of the anchor M 0 = characteristic flexural strength ( resistance ) of the anchor s
N ua
= highest factored tension load acting on the anchor
ϕN sa
= tension design steel strength ( resistance ) of the anchor The shear design bending strength ϕV M s
( resistance ) is checked against the factored shear load ( V ua ) acting on the anchor .
Concrete breakout strength in tension ( 17.4.2 ) ϕN cb
≥ N ua ϕN cbg
≥ N ua , g
Pullout strength in tension ( 17.4.3 ) ϕN pn ≥ N ua ϕN pn
≥ N ua , i
Concrete side-face blowout strength in tension ( 17.4.4 )
Bond strengh of adhesive anchor in tension ( 17.4.5 ) ϕN sb
≥ N ua
ϕN a
≥ N ua ϕN sbg
≥ N ua , g
ϕN ag
≥ N ua , g
331 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions