PROFIS ENGINEERING
Table 40. Interaction
Tri-Linear: N ua ϕN n
+ V ua ϕV n
≤ 1.2
0.422 + 0.149 = 0.571 < 1.2 OK
Parabolic: N 5 5
ua 3 V ua + 3 ≤ 1. 0 ϕN n ϕV n
ACI 318-19 Eq.( 17.8.3)
Reference ACI 318-19 commentary R17.8.
( 0.422) 5 / 3 +( 0.149) 5 / 3 = 0.237 + 0.042 = 0.279 < 1.0 OK FASTENING MEETS THE DESIGN CRITERIA.
SUMMARY Shear Load Acts Towards the x- Edge
• Shear load acts in the-y direction, parallel to the x- and x + edges.
• Assume shear load acts towards x- edge: consider concrete breakout for anchor columns 1 and 2.
• c a1, col 1 with respect to the x- edge is less than s x12
• Case 1 / Case 2 is relevant with respect to the x- edge for col 1 and col 2.
• y direction anchor spacing is less than 3c a1, col 1
• Assume anchors in each column act as a group
• Calculate concrete breakout( ϕV cbg) from col 1 using c a1, col 1 with respect to the x- edge.
• Case 1 / Case 2 assumes 0.5V ua, y acts on col 1
• Calculate concrete breakout( ϕV cbg) from col 2 using c a1, col 2 with respect to the x- edge.
• Case 1 / Case 2 assumes 1.0V ua, y acts on col 2
Shear Load Acts Towards the x + Edge
• Shear load acts in the-y direction, parallel to the x- and x + edges.
• Assume shear load acts towards x + edge: consider concrete breakout for anchor columns 1 and 2.
• c a1, col 2 with respect to the x + edge is greater than s x12
• Case 3 is relevant with respect to the x + edge for col 1 and col 2.
• y direction anchor spacing equals than 3c a1, col 2
• Assume anchors in each column act as a group
• Calculate concrete breakout( ϕV cbg) from col 2 using c a1, col 2 with respect to the x + edge.
• Assume failure surface from col 1 merges with failure surface from col 2
• Case 3 assumes 1.0V ua, y acts on col 2
Interpreting the Design Results
•( N ua / ϕN cbg) controls the design for tension failure modes
• Shear concrete breakout assumptions
• Case 1 / Case 2: check ϕV cbg, col 1 with respect to the x- edge vs. 0.5V ua, y
• Case 1 / Case 2: check ϕV cbg, col 2 with respect to the x- edge vs. 1.0V ua, y
• Case 3: check ϕV cbg, col 2 with respect to the x + edge vs. 1.0V ua, y CONTROLS
•( 1.0V ua, y / ϕV cbg, col 2) with respect to the x + edge controls the design for shear failure modes
• Tension / shear interaction is satisfied if parabolic equation is used.
• Fastening satisfies ACI 318-19 provisions.
For more information on extrapolating ACI 318 shear concrete breakout provisions with respect to this design example, reference Shear Load Parallel to Two Edges( page 30) in the design guide.
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