Williams Form Engineering Corp. - S-9 Undercut Concrete Anchor System Design Considerations

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S-9 Undercut Concrete Anchor Design Considerations

Williams has listed recommended embedment depths that are minimum values for ductile steel failure design in 3000 psi concrete. Embedment depths will need to increase according to the values determined from anchor design models when spacing requirements are less than the values listed below (S). A reduction in anchor capacity should be used if the concrete thickness does not allow for deeper embedments. Appropriate reduction factors can be calculated from industry design models. When placing anchors that require a smaller edge distance than what is recommended in the table below, the designer should be aware of a reduction in anchor capacity. Table information below can be used as a reference when reduced edge distance is a factor in anchor design. The values for reduced edge distance are based on tests in 3000 to 4000 psi non-reinforced concrete and should only be used as a reference in combination with reduction values calculated from industry design models.

Grade B7 S-9 Undercut Anchors - Minimum Spacing & Edge Distances

Bar Diameter	Anchor Length	Flush Mount Anchor Length	Embedment Depth	Attachment Thickness	Center to Center Spacing for Full Strength with no Reduction (S)	Minimum Recomm. Edge Distance (E)	Minimum Ultimate Strength	Concrete Failure Loads
								4 Bar ø from the Edge (Test)	6 Bar ø from the Edge (Test)	8 Bar ø from the Edge (Test)
1/4" (6.4 mm)	4-1/2" (114 mm)	-	3" (76 mm)	1" (25 mm)	6" (152 mm)	3" (76 mm)	3.98 kips (17.7 kN)	N.A.	N.A.	N.A.
3/8" (10 mm)	6" (152 mm)	3-3/4" (95 mm)	3-1/2" (89 mm)	1" (25 mm)	7" (178 mm)	5" (127 mm)	9.69 kips (43.1 kN)	N.A.	N.A.	N.A.
	8" (203 mm)	-	3-1/2" (89 mm)	3" (76 mm)
	11" (279 mm)	-	6-1/2" (165 mm)	3" (76 mm)
1/2" (12 mm)	8" (203 mm)	5-5/8" (143 mm)	6" (152 mm)	1" (25 mm)	12" (305 mm)	6" (152 mm)	17.7 kips (78.9 kN)	4 kips (17.9 kN)	8 kips (35.6 kN)	16 kips (71.2 kN)
	10" (254 mm)	-	6" (152 mm)	3" (76 mm)
	12" (305 mm)	-	8" (203 mm)	3" (76 mm)
5/8" (16 mm)	10" (254 mm)	7-1/8" (181 mm)	7-1/2" (191 mm)	1" (25 mm)	15" (381 mm)	8" (203 mm)	28.2 kips (125 kN)	16 kips (71.2 kN)	29 kips (129 kN)	N.A.
	12" (305 mm)	-	7-1/2" (191 mm)	3" (76 mm)
	15" (381 mm)	-	10" (254 mm)	3" (76 mm)
3/4" (20 mm)	13" (330 mm)	8-3/4" (222 mm)	9-1/4" (235 mm)	2" (51 mm)	18-1/2" (470 mm)	11" (279 mm)	41.8 kips (187 kN)	20 kips (89 kN)	34 kips (151 kN)	41 kips (182 kN)
	16" (406 mm)	-	9-1/4" (235 mm)	5" (127 mm)
	19" (483 mm)	-	12-1/4" (311 mm)	5" (127 mm)
1" (25 mm)	17" (432 mm)	11-7/8" (302 mm)	12-1/2" (318 mm)	2" (51 mm)	25" (635 mm)	14" (356 mm)	75.3 kips (337 kN)	25 kips (111 kN)	50 kips (222 kN)	N.A.
	20" (508 mm)	-	12-1/2" (318 mm)	5" (127 mm)
	23" (584 mm)	-	15-1/2" (394 mm)	5" (127 mm)
1-1/4" (32 mm)	21" (533 mm)	15-1/4" (387 mm)	16" (406 mm)	2" (51 mm)	32" (813 mm)	18" (457 mm)	121 kips (539 kN)	50 kips (222 kN)	90 kips (400 kN)	107 kips (476 kN)
	25" (635 mm)	-	16" (406 mm)	6" (152 mm)
	30" (762 mm)	-	21" (533 mm)	6" (152 mm)
1-1/2" (38 mm)	31" (787 mm)	20-1/2" (520 mm)	21-1/2" (546 mm)	2" (51 mm)	43" (1092 mm)	23" (584 mm)	176 kips (781 kN)	N.A.	N.A.	N.A.

(N.A.) No test data available
Standard sizes are shown, special lengths available on request.
Tests were performed on A193 Grade B7 products and values will be conservative for Stainless Steel S-9 Anchors.
Concrete compressive strengths were between 3000-4000 psi unreinforced concrete.
Anchor embedment depth will vary with respect to anchor spacing.
Flush mount anchor length Includes coupling.
Attachment thickness for flush mount by others. Attachment bolt length or stud rod length are as required.
(*) 4-1/8” minimum embedment for flush mount.