PROFIS ENGINEERING
Figure 5.1b. ACI 318 Provisions – s x1-6 and s x6-4 < c a1, 1x
Reference
[ 36 ] above. Consider shear concrete breakout towards the x- edge for anchors 1, 6 and 4. Anchor 1 is the closest anchor to the x- edge. The distance of anchor 1 to the x- edge equals c a1, 1x. If the spacing in the x direction between anchors 6 and 4( s x6-4) is less than c a1, 1x, the failure surface for anchor 4 merges with the failure surface for anchor 6( blue shaded area). If the spacing in the x direction between anchors 1 and 6( s x1-6) is less than c a1, 1x, the failure surface for anchor 6 merges with the failure surface for anchor 1( yellow shaded area). Therefore, Case 3 provisions are relevant for calculating shear concrete breakout because a complete concrete failure surface can only develop towards the x- edge from anchor 1( red shaded area). The x component of the shear load( V ua, x) will be assumed to act towards the x- edge.
Nominal concrete breakout strength( V cb, nn) is calculated for anchor 1( V cb, 1x). The design concrete breakout strength( ϕV cb, 1x) is checked versus 1.0V ua, x since Case 3 provisions are relevant.
The design calculations can be summarized as follows:
• assume 1.0V ua, x, acts on anchor 1 check( 1.0V ua, x / ϕV cb, 1x) ≤ 1.0( 1.0V ua, x / ϕV cb, 1x) controls the design with respect to shear concrete breakout towards the x- edge.
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