PROFIS ENGINEERING
Shear Load – One Load Direction – One Fixed Edge
Figure 6.1.
Reference Figure 6.1 [ 47 ]. It illustrates a hypothetical anchorage consisting of sixteen anchors. The anchors are aligned to form rows in the x direction and columns in the y direction. With respect to concrete breakout in shear, the anchors in each row / column are assumed to act as a group. ACI 318 provisions for shear concrete breakout assume the applied shear load( V ua) acts towards a fixed edge, causing concrete breakout failure to occur at that edge. Per Figure 6.1 [ 47 ], V ua acts towards the y- edge. A nominal concrete breakout strength( V cbg) is calculated with respect to all rows from which a concrete failure surface is assumed to develop. The calculated design concrete breakout strength( ϕV cbg) is checked versus V ua.
Determining from which row( s) a concrete failure surface can develop is predicated on the spacing between each row in the direction of the applied shear load( e. g. s y, nn for this example). Per ACI 318 Case 1 / Case 2 provisions, if s y, nn between any two adjacent rows is greater than or equal to the edge distance for the anchor row nearest the fixed edge being considered( e. g. s y, nn ≥ c a1, row 1 for this example), a complete concrete breakout failure surface can develop from each row. Per ACI 318 Case 3 provisions,( for this example), if s y, nn between any two adjacent rows is less than c a1, row 1, a complete concrete breakout failure surface can only develop from the anchor row nearer to the fixed edge being considered.
ACI 318 Case 1 / Case 2 provisions assume the value for V ua assumed to act on a particular row is proportionate to the total number of rows being considered for concrete breakout, and the number of anchors in each row.
V row, i = max V total ⋅ i
N rows
, V total ⋅ y
∑ n row, i i = 1 n total where:
• V total = the total shear load acting on the anchorage.
• i = the row number.
• N rows = total number or rows considered to resist shear
• n row, i = number of anchors in row i
• n total = total number of anchors in the anchorage.
Shear Load Evaluation – One Load Direction – One Fixed Edge( page 48) explains how V ua is calculated when s y, nn ≥ c a1, row 1 ……….
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