|
c Na
= 10d a
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т uncr
1100
|
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
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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 .
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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 )
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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
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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 :
c Na
|
• ψ ed , Na
:
• ψ cp , Na :
|
Modification factor for a fixed edge distance less than c Na
. Reference
Section 17.4.5.4
Modification factor to consider splitting failure . Reference Section 17.4.5.5
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If c a , min ≥ c Na
, then ψ ed , Na = 1.0 ( 17.4.5.4a )
|
Reference the Variables section of the PROFIS Engineering report for more information on the following parameters :
d a
: Diameter of anchor element
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If c a , min < c Na
, then ψ ed , Na = 0.7 + 0.3
|
c a , min ( 17 . 4 . 5 . 4b )
c Na
|
т uncr
:
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Characteristic bond stress of an adhesive anchor in uncracked concrete |
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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 :
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Reference the Calculations section of the PROFIS Engineering report for more information on the following parameters :
A Na
: Area of influence modification factor
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If c a , min < c ac
, then ψ cp , Na = c
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a , min |
( 17.4.5.5b ) |
c ac
|