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ψ ed , N
= 0.7 + 0.3
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c a , min ≤1 . 0
1.5h ef
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17.6 . 2.4.1 Modification factor for edge effects for single anchors or anchor groups loaded in tension , ψ ed , N
, shall be determined by ( a ) or ( b ).
( a ) If c a , min ≥ 1.5h ef
, then ψ ed , N = 1.0 ( 17.6.2.4.1a )
( b ) If c a , min < 1.5h ef
, then ψ ed , N = 0.7 + 0.3
c a , min ( 17 . 6 . 2 . 4 . 1b )
1.5h ef
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ψ ed , N is a modification factor that is used to account for fixed edge distances less than 1.5h ef
. The parameter h ef corresponds to the effective embedment depth that has been selected for the anchor being modeled in PROFIS Engineering . When calculating the nominal concrete breakout strength in tension ( N cb or N cbg ), the model used to define the projected concrete failure area ( A Nc
) limits the maximum edge distance for calculation purposes to a projected distance of 1.5h ef from the anchors in tension . PROFIS Engineering will use a projected distance of 1.5h ef from an anchor , or row of anchors , to define an outer edge of the area defined by
A Nc when the fixed edge distance from the anchor ( s ) is greater than 1.5h ef , or the edge is infinite .
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ψ ed , N is calculated whenever a fixed edge distance from an anchor ( s ) in tension is less than 1.5h ef
. The parameter c a , min in the ψ ed , N equation corresponds to a fixed edge distance less than 1.5h ef . ACI 318 anchoring-to-concrete provisions define c a , min as the “ minimum distance from the center of an anchor shaft to the edge of concrete ”. When more than one fixed edge distance is less than 1.5h ef
, the smallest value is input as c a , min , and used to calculate ψ ed , N
.
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The illustration below shows how the projected concrete failure area ( A Nc
) would be defined for an anchoring application being modeled with two fixed edges ( c a1 and c a2 ) that are both less than 1.5h ef
, and with c a1 being less than c a2
. The smallest edge distance ( c a1 ) corresponds to the parameter c a , min
, that would be used to calculate the modification factor ψ ed , N .
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ψ ed , N
= 0.7 + 0.3 ( c a1 / 1.5h ef
)
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Reference the Variables section of the PROFIS Engineering report for more information on the following parameters :
c a , min
: parameter for the smallest fixed edge being modeled .
h ef
: parameter for anchor effective embedment depth .
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