PROFIS ENGINEERING
Equal Number of Anchors and Equal Spacing – Case 3
Figure
3.2.
Reference Figure 3.2 [ 8 ]. 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 less than c a1, row 1 and the spacing in the direction of the V ua between row 2 and row 3( s y23) is less than c a1, row 1. Case 3 is relevant for row 1, row 2 and row 3 because the concrete breakout failure surfaces from rows 2 and 3 will merge with the failure surface from row 1.
• Case 3 assumes the total shear load V ua acts on row 1 because a full concrete breakout failure surface can only develop from row 1.
• V ua, row 1 = 1.0V ua
• Calculate the design concrete breakout strength for row 1( ϕV cbg, row 1) using the edge distance in the direction of the shear load for row 1( c a1, row 1).
• Check the utilization( V ua, row 1 / ϕV cbg, row 1)
• Design for concrete breakout in shear is satisfied if( 1.0V ua / ϕV cbg, row 1) ≤ 1.0
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