PROFIS ENGINEERING
Extrapolating ACI 318 Provisions for Shear – Uniform Square or Rectangular Anchor Layouts
Figure
3.
Reference Figure 3 [ 6 ]. It illustrates an anchorage consisting of sixteen anchors: four rows of anchors with four anchors in each row. A shear load( V ua) acts towards the y- edge. ACI 318 provisions for considering concrete breakout in shear are defined via Case 1, Case 2 and Case 3 in terms of two anchor rows having one anchor in each row. Considering whether Case 1, Case 2 or Case 3 controls for an anchorage consisting of multiple rows and anchors requires consideration of the following parameters:
• Anchor rows assumed to resist shear load( e. g. row 1 and / or rows 2, 3, 4)
• Spacing( s ynn) between each row in the direction of the applied shear load( e. g. s y12, s y23, s y34).
• Distance of the near row anchors( e. g. anchors in row 1) to the fixed edge( e. g. c a1, row 1).
• Check s ynn for any two adjacent rows( e. g. s y12, s y23, s y34) versus c a1, row 1.
• For any two adjacent rows, determine whether Case 1 / Case2 are applicable or Case 3
• Based on which case is applicable, determine the magnitude of shear load( V ua, row n) assumed to act on each relevant row.
• Calculate the design concrete breakout strength( ϕV cbg, row n) for each relevant row using the edge distance in the direction of the shear load for that row( c a1, row n).
• Check the utilization for each relevant row( V ua, row n / ϕV cbg, row n).
• Design is satisfied if( V ua, row n / ϕV cbg, row n) ≤ 1.0 for each row being considered.
• MAX { V ua, row n / ϕV cbg, row n } controls the anchorage design with respect to concrete breakout in shear.
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