PROFIS ENGINEERING
Equal Number of Anchors and Equal Spacing – Case 1 / Case 2
Figure 3.1.
Reference
Figure 3.1 [ 7 ]. It illustrates a hypothetical anchorage consisting of sixteen anchors. The anchor spacing in the x direction is less than 3c a1, row 1 so the anchors in each row act as a group( e. g. reference ACI 318-19 Section 17.5.1.3.1). The shear load( V ua) is assumed to act on only the first three rows( row 1, row 2 and row 3). For this anchorage, ACI 318 provisions for considering concrete breakout in shear would be extrapolated as follows.
• The spacing in the direction of V ua between row 1 and row 2( s y12) is greater than c a1, row 1 and the spacing in the direction of the V ua between row 2 and row 3( s y23) is greater than c a1, row 1. Case 1 and Case 2 are relevant for row 1, row 2 and row 3.
• Case 1 and Case 2 must be considered with respect to all three rows, so the shear load V ua is distributed proportionally over each row. i
• V ua, row n = V N ua, total rows
• where i = the row number and N rows = number of rows being considered
• V ua, row 1 =( 1 / 3)( V ua) = 0.33V ua
• V ua, row 2 =( 2 / 3)( V ua) = 0.67V ua
• V ua, row 3 =( 3 / 3)( V ua) = 1.0V ua
• Calculate the design concrete breakout strength( ϕV cbg, row n) for row 1, row 2 and row 3 using the edge distance in the direction of the shear load for that row( c a1, row n).
• Calculate ϕV cbg, row 1 using c a1, row 1
• Calculate ϕV cbg, row 2 using c a1, row 2
• Calculate ϕV cbg, row 3 using c a1, row 3
• Check the utilization( V ua, row n / ϕV cbg, row n) for row 1, row 2 and row 3.
• Check( 0.33V ua / ϕV cbg, row 1) ≤ 1.0 for row 1
• Check( 0.67V ua / ϕV cbg, row 2) ≤ 1.0 for row 2
• Check( 1.0V ua / ϕV cbg, row 3) ≤ 1.0 for row 3
• MAX { V ua, row n / ϕV cbg, row n } controls for concrete breakout in shear.
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