COMBINED TENSION AND SHEAR LOAD
Parabolic
Results Status
Results ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering Status
R17.8 — Tension and Shear Interaction The tension-shear interaction expression has traditionally been expressed as
N ua
N n
E
+
where ζ varies from 1 to 2 . The current trilinear recommendation is a simplification of the expression where ζ = 5 / 3 . The limits were chosen to eliminate the requirement for calculation of interaction effects where very small values of the second force are present . Any other interaction expression that is verified by test data , however , can be used to satisfy 17.5.2.3 .
V ua
V n
E
≤ 1.0
PROFIS Engineering designates the parameter ( N ua / ϕN n
) as ” β N
”, and shows it as a percentage (%) in the report under the heading “ Status ”. ACI 318-19 anchoringto-concrete provisions for tension are satisfied if all the β N
-values for the tension failure modes being considered are ≤ 100 %. The highest β N
-value corresponds to the “ controlling ” or “ governing ” failure mode in tension , and is used as the tension component in the parabolic equation given in the commentary R17.8 .
PROFIS Engineering designates the parameter ( V ua / ϕV n
) as ” β V
”, and shows it as a percentage (%) in the report under the heading “ Status ”. ACI 318-19 anchoringto-concrete provisions for shear are satisfied if all the β V
-values for the shear failure modes being considered are ≤ 100 %. The highest β V
-value corresponds to the “ controlling ” or “ governing ” failure mode in shear , and is used as the shear component in the parabolic equation given in the commentary R17.8 .
For the example below , all the β N
-values are ≤ 100 %; therefore , PROFIS Engineering shows the “ Status ” for each value as “ OK ” since ACI 318 anchoringto-concrete provisions are satisfied . Concrete Breakout Failure is the governing failure mode for tension because it has the highest utilization ( β N
= 51 %). This value is used as the tension component in the parabolic equation . However , the β V
-value for Concrete Edge Failure in direction x + is > 100 % ( β V = 130 %); therefore , PROFIS Engineering shows the “ Status ” for this β V
-value as “ not recommended ” since ACI 318 anchoring-to-concrete provisions are not satisfied .
β V
= 130 % is also the governing failure mode for shear because it has the highest utilization . This value is used as the shear component in the parabolic equation .
Reference ACI 318-19 Fig . R17.8 .
The PROFIS Engineering anchor portfolio includes post-installed mechanical anchors , postinstalled adhesive anchors , and cast-anchors . The following tension failure modes are considered for each anchor :
post-installed mechanical anchor |
steel strength : |
β N
= N ua ( i ) / ϕ steel
N sa
|
pullout strength : |
β N
= N ua ( i ) / ϕ concrete
N pn , ƒ ́c
|
concrete breakout strength : |
β N
= N ua ( i ) / ϕ concrete
N cb or β N = N ua ( g )
/ ϕ concrete
N cbg
|
post-installed adhesive anchor |
steel strength : |
β N
= N ua ( i ) / ϕ steel
N sa
|
bond strength : |
β N
= N ua ( i ) / ϕ bond
N a or β N = N ua ( g )
/ ϕ bond
N ag
|
sustained tension load |
( for bond strength ): |
β N
= N ua ( i ) / 0.55ϕ bond
N ba
|
concrete breakout strength : |
β N
= N ua ( i ) / ϕ concrete
N cb or βN = N ua ( g ) / ϕ concrete
N cbg
|
3 Tension load
Load N ua [ lb ]
Capacity
ϕN n
[ lb ]
Utilization
β N
= N ua / ϕN n
Status
Steel strength * 5,000 14,550 35 OK Bond strength ** 10,000 31,564 32 OK Sustained tension load bond strength * 3,450 16,800 21 OK Concrete breakout Failure ** 10,000 19,971 51 OK
* highest loaded anchor ** Anchor group ( anchors in tension )
4 Shear load Load V ua
[ lb ]
Capacity ϕV n [ lb ]
Utilization
β N
= V ua / ϕV n
Status
Steel strength * 3,750 8,221 46 OK
Steel failure with lever arm *
Pryout ( bond strength controls )*
Concrete edge failure in direction x + **
* highest loaded anchor ** Anchor group ( relevant anchors )
N / A N / A N / A N / A
15,000 76,400 20 OK
15,000 11,592 130 not recommended
347 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions