Staggered-Hole Net Width (AISC 360 B4.3b)
The zigzag chain steel-tension-member says it does not handle. B4.3b deducts the diameters of ALL holes in a diagonal chain and then ADDS s^2/4g for each gage space it crosses, and every possible chain has to be checked with the SMALLEST net width governing. Two things get missed: the hole comes off at the bolt diameter plus 1/8 in, not the bolt diameter, which overstates the area on every hole in the chain; and staggering has a CEILING -- past a computable pitch the straight chain governs and further stagger buys nothing at all. The tile names that pitch, which is the number worth having before the pattern gets redrawn.
Formula and source
hole diameter deducted = bolt diameter + allowance (1/8 in default). Straight chain net width = W - n_straight x hole. Zigzag chain net width = W - n_zigzag x hole + k x s^2/(4g), k gage spaces crossed. The smaller governs; An = governing net width x thickness. The pitch at which the two chains are equal is s = sqrt(4 g (n_zigzag - n_straight) x hole / k).
AISC 360 Section B4.3b (Net Area).
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