TylerM94
Structural
- Jun 2, 2020
- 26
Looking for a gut check to confirm an equivalent mechanical fastener attachment pattern to using 5/8" puddle welds at 8 inches on center. The situation I have is connecting new metal deck to existing metal deck. I came up with #10 screws at 3 inches on center is equivalent to 5/8" puddle welds at 8 inches on center.
Metal Deck: Vulcraft 3NL-32, 18 Gage (t=0.0474 in), Fy = 50 ksi, Fu = 65 ksi, G60 Galvanized Sheet.
Check Deck in Tension:
Pn = 0.7*t*da*Fu = 0.7*0.0474*0.5302 (Type B Double Thickness of Sheet)*65 ksi = 1,143 lbs
Using a #10 screw with 18 gage base metal, the SDI deck table I consulted provides a tensile capacity of Pn = 473 lbs. Solving for the equivalent spacing I get 3.3 inches.
Check Deck in Shear:
Pn = 0.88*t*da*Fu
Pn = 0.88*0.0474*0.5302*65 = 1,437.5 lbs
Using a #10 screw with 18 gage base metal, the SDI deck table I consulted provides a shear capacity of Pn = 789 lbs. Solving for the equivalent spacing I get 4 inches.
Tension controls in this case. Does it seem reasonable that an equivalent to 5/8" puddle welds at 8 inches on center is #10 screws at 3 inches on center? This seems like very close spacing to me.
Metal Deck: Vulcraft 3NL-32, 18 Gage (t=0.0474 in), Fy = 50 ksi, Fu = 65 ksi, G60 Galvanized Sheet.
Check Deck in Tension:
Pn = 0.7*t*da*Fu = 0.7*0.0474*0.5302 (Type B Double Thickness of Sheet)*65 ksi = 1,143 lbs
Using a #10 screw with 18 gage base metal, the SDI deck table I consulted provides a tensile capacity of Pn = 473 lbs. Solving for the equivalent spacing I get 3.3 inches.
Check Deck in Shear:
Pn = 0.88*t*da*Fu
Pn = 0.88*0.0474*0.5302*65 = 1,437.5 lbs
Using a #10 screw with 18 gage base metal, the SDI deck table I consulted provides a shear capacity of Pn = 789 lbs. Solving for the equivalent spacing I get 4 inches.
Tension controls in this case. Does it seem reasonable that an equivalent to 5/8" puddle welds at 8 inches on center is #10 screws at 3 inches on center? This seems like very close spacing to me.