PROFIS ENGINEERING
Reference Figure 6.4c [ 67 ]. The resultant shear load( V res) is calculated using the torsion load components acting on the anchors. For this example, PROFIS Engineering would calculate the x component of the resultant shear load using only the torsion load components acting parallel to the y- fixed edge that are closest to this edge( e. g. F tor, 1, x, F tor, 2, x, F tor, 3, x and F tor, 4, x). The torsion load components acting parallel to the y- fixed edge that are farther from this edge( e. g. F tor, 5, x, F tor, 6, x, F tor, 7, x and F tor, 8, x) are not considered to have any influence on the y- fixed edge. PROFIS Engineering would calculate the y component of the resultant shear load using only the torsion load components that act towards the y- fixed edge( e. g. F tor, 1, y, F tor, 2, y, F tor, 5, y and F tor, 6, y). The torsion components acting away from the y- fixed edge( e. g. F tor, 3, y, F tor, 4, y, F tor, 7, y and F tor, 8, y) are not considered to have any influence on the y- fixed edge.
Reference Table 6.4. The resultant shear load would be calculated as follows:
V x = F tor, 1, x + F tor, 2, x + F tor, 3, x + F tor, 4, x = 3808lb V y = F tor, 1, y + F tor, 2, y + F tor, 5, y + F tor, 6, y = 6098lb
V res =
V x
2 + Vy
2 = 7189lb
The torsion load components in the x direction are all equal; therefore, V x acts at the centroid of the anchor group. Since the torsion load components in the y direction are not equal, V y acts at a distance x from the centroid of the anchor group. The distance of V y from the centroid of the anchor group can be determined by multiplying each y component by its +/- distance from the centroid of the anchor group and dividing the sum of these results by V y. However, PROFIS Engineering conservatively assumes the resultant load( V res) acts towards the y- edge instead of only the y component( V y). Therefore, PROFIS Engineering would calculate the parameter“ x” in Figure 6.4c [ 67 ] as follows:
F tor, 1, y −12in + F tor, 5, y −12in + F tor, 2, y −4in + F tor, 6, y −4in = V res xin x = − 8.48in
V res acts 8.48in in the x − direction from the centroid of the anchor group
V res is eccentric with respect to the centroid of the anchors in shear by a distance 8.48 in in the x- direction. This distance corresponds to the ACI 318 parameter for shear eccentricity( e’ V), which is used to calculate a modification factor for eccentricity( ψ ec, V), that is used to calculate the nominal concrete breakout strength in shear( V cbg). PROFIS Engineering designates from the shear eccentricity parameter“ e c, V” instead of“ e’ V”, but the PROFIS Engineering calculations are the same as the ACI 318 provisions. For this example:
• e c, V =( x in) = 8.48 in
• e c, V is used to calculate the ACI 318 modification factor for shear eccentricity( ψ ec, V)
1 ψ ec, V =
1 + e c, V
1.5c a1
• ψ ec, V is used to calculate the nominal concrete breakout strength in shear( V cbg)
V cbg = A Vc
A Vco ψ ec, V ψ ed, V ψ c, V ψ h, V V b
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