PART 4 SHEAR LOAD
Pryout Failure Mode ( Pryout Bond )
Variables c Na
Variables 318-14 Chapter 17 Provision Comments for PROFIS Engineering
c Na
17.4.5.1 ……… A Na is the projected influence area of a single adhesive anchor or group of adhesive anchors that shall be approximated as a rectilinear area that projects outward a distance c Na from the centerline of the adhesive anchor , or in the case of a group of adhesive anchors , from a line through a row of adjacent adhesive anchors ……..………………. A Na0 is the projected influence area of a single adhesive anchor with an edge distance equal to or greater than c Na
. where
and the constant 1100 carries the unit of lb / in 2 .
A Na0
= ( 2c Na ) 2 ( 17.4.5.1c ) c Na
= 10d a т uncr 17 . 4 . 5 . 1d 1100
17.4.5.3 The modification factor for adhesive anchor groups loaded eccentrically in tension , ψ ec , Na shall be calculated as : ψ ec , Na
=
1
1 + e ́N
( 17.4.5.3 )
17.4.5.4 The modification factor for edge effects for single adhesive anchors or adhesive anchor groups loaded in tension , ψ ed , Na
, shall be calculated as If c a , min
≥ c Na , then ψ ed , Na
= 1.0 ( 17.4.5.4a )
c Na
If c a , min < c Na
, then ψ ed , Na = 0.7 + 0.3 c a , min ( 17 . 4 . 5 . 4b )
17.4.5.5 The modification factor for adhesive anchors designed for uncracked concrete in accordance with 17.4.5.2 without supplementary reinforcement to control splitting , ψ cp , Na
, shall be calculated as : If c a , min
≥ c ac , then ψ cp , Na
= 1.0 ( 17.4.5.5a )
If c a , min < c ac
, then ψ cp , Na c Na
c a , min ( 17 . 4 . 5 . 5b ) but ψ cp , Na determined from Eq . ( 17.4.5.5b ) shall not be taken less than c Na
/ c ac , where the critical distance c ac is defined in 17.7.6 . For all other cases , ψ cp , Na shall be taken as 1.0 . c ac
ACI 318-14 Chapter 17 bond strength calculations are predicated on the parameter “ c Na
”, which is defined in Chapter 2 as the “ projected distance from the center of an anchor shaft on one side of the anchor required to develop the full bond strength of a single adhesive anchor ”. c Na is calculated per Equation ( 17.4.5.1d ).
The parameter “ d a
” corresponds to the diameter of the anchor element selected for the PROFIS Engineering application being modeled . The parameter “ т uncr
” corresponds to the characteristic bond stress in uncracked concrete of the adhesive product selected for the PROFIS Engineering application being modeled .
The modification factor A Na accounts for the area of influence assumed to develop with respect to bond failure , for the edge conditions and anchor spacing that have been input into the PROFIS Engineering model . Per the provisions for A Na given in Section 17.4.5.1 , PROFIS Engineering limits the geometry used to define A Na to a maximum projected distance from an anchor of c Na . c Na is also used to calculate the following bond strength parameters :
• A Na0
: modification factor for the idealized area of influence assumed to develop in concrete , with respect to bond failure , for a single anchor without any edge influences . Reference Equation ( 17.4.5.1c )
• ψ ec , Na
: modification factor for an eccentric tension load acting on a group of anchors . Reference Section 17.4.5.3
• ψ ed , Na : modification factor for a fixed edge distance less than c Na
. Reference
Section 17.4.5.4
• ψ cp , Na
: modification factor to consider splitting failure . Reference Section 17.4.5.5
Reference the Variables section of the PROFIS Engineering report for more information on the following parameters :
d a
: Diameter of anchor element
т uncr
: Characteristic bond stress of an adhesive anchor in uncracked concrete
Reference the Calculations section of the PROFIS Engineering report for more information on the following parameters :
A Na
:
A Na0
:
ψ ec , Na
:
ψ ed , Na
:
ψ ec , Na
:
Area of influence modification factor Idealized area of influence modification factor for a single anchor Modification factor for tension eccentricity Modification factor for edge distance Modification factor for splitting
232 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions