PROFIS ENGINEERING
Band Width Approach
Band Width Approach for Irregular Anchor Layouts
Figure 5.2. Band Width Approach for Shear Concrete Breakout
Reference
[ 38 ]. The“ band width” approach permits consideration of shear concrete breakout when no two anchors are aligned to form either a row or a column. In [ 38 ], no two anchors align in the x direction to form a row( yellow dashed lines) or in the y direction to form a column( green dashed lines). Therefore, no two anchors are aligned equidistant from either the y- edge( yellow dashed lines) or the x- edge( green dashed lines). The band width approach can be utilized to consider shear concrete breakout for this application.
A length( L x / y) will be defined as the distance in the assumed direction of the shear load( V ua, x / y) between the outermost anchors. This length( L x / y) is multiplied by a factor of 0.25 to give a“ band width”, shown in the purple shaded areas. Anchors spaced in the direction of the shear load that are within the band width will be treated as if they were formed in a row or column, perpendicular to the direction of the shear load, i. e. as if they were equidistant from the fixed edge where breakout is assumed to occur. Regardless of the spacing between anchors in the direction of the shear load within the band width, ACI 318 Case 3 will be assumed. In other words, the total shear load will be assumed to act on a single“ row / column” defined by the anchors with the band width. The distance from the anchor within the band width that is closest to the edge where concrete breakout is assumed will be used as the c a1-value when calculating the design concrete breakout strength( ϕV cbg). The area of influence( A Vc) used to calculate ϕV cbg is defined by( a) the anchor spacing within the band width that is perpendicular to the direction of the shear load and( b) the concrete geometry( edge distances) that are perpendicular to the direction of the shear load. Reference the yellow and red shaded areas. Limits on spacing perpendicular to the direction of the shear load( s < 3c a1) should be considered with respect to group action per ACI 318 provisions( e. g. ACI 318-19 Section 17.5.1.3.1).
Band Width Approach – Concrete Breakout Towards the x- Edge( page 41) will discuss how to consider the band width approach to calculate concrete breakout towards the x- edge for the application illustrated in [ 38 ]. Band Width Approach – Concrete Breakout Towards the y- Edge( page 40) will discuss how to consider the band width approach to calculate concrete breakout towards the y- edge for the application illustrated in [ 38 ].
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