

S9 Undercut Concrete Anchor System









Williams S9 Undercut Bearing Anchor was designed to eliminate the direct lateral stress found in the setting of conventional anchors and to bring its characteristics closer to those of castinplace anchors. Through the use of Williams undercutting tool, along with Williams undercut anchor, the conical shape of the anchor fits into the conical cut of the hole. This produces a positive expansion anchoring system that develops the tensile capacity of the bolt without slip or concrete failure. Because the anchor head is larger than the drill hole size, a properly embedded anchor will consistently develop 100% of the ASTM A193 Grade B7 bolting material. 












Advantages of Williams Undercut Anchor




 Cyclic Loading in Cracked Concrete  In situations where the diameter of the hole is increased due to changes caused by nature, the S9 Undercut Bearing Anchor withstands cyclic loads in the cracked concrete member because the undercut of the hole is much larger than the top of the hole.
 High Levels of Preload  Williams high strength stud bolt is threaded the total length of the bar to provide uniform stress throughout the bolt. When combined with Williams undercut head assembly the product is an anchor which will retain a much higher preload than a standard friction anchor.
 Vibratory Loads  Throughout the destructive testing on Williams undercut anchor there has been consistent ductile failure on the stud bolt demonstrating a high reliability of safety. Therefore the S9 Undercut anchor may be used safely with vibration equipment and piping.








S9 Undercut Concrete Anchor  ASTM A193 Grade B7 



Stud
Diameter 
Drill
Hole
Diameter 
Minimum
Ultimate Strength
(FpuA) (2) 
Minimum
Yield
Strength 
Allowable
Tension
.5 (FpuA) 
Allowable
Simple Shear
.17 (FpuA) (1) 
1/4"  20 UNC
(6.4 mm) 
5/8"
(16 mm) 
3.98 kips
(17.7 kN) 
3.34 kips
(14.9 kN) 
1.99 kips
(8.92 kN) 
0.677 kips
(3.01 kN) 
3/8"  16 UNC
(10 mm) 
7/8"
(22 mm) 
9.69 kips
(43.1 kN) 
8.14 kips
(36.2 kN) 
4.84 kips
(21.5 kN) 
1.65 kips
(7.34 kN) 
1/2"  13 UNC
(12 mm) 
7/8"
(22 mm) 
17.7 kips
(78.9 kN) 
14.9 kips
(66.3 kN) 
8.85 kips
(39.4 kN) 
3.01 kips
(13.4 kN) 
5/8"  11 UNC
(16 mm) 
11/8"
(29 mm) 
28.2 kips
(125 kN) 
23.7 kips
(105 kN) 
14.5 kips
(64.5 kN) 
4.93 kips
(22.0 kN) 
3/4"  10 UNC
(20 mm) 
11/8"
(29 mm) 
41.8 kips
(187 kN) 
35.1 kips
(156 kN) 
20.9 kips
(93.6 kN) 
7.11 kips
(31.6 kN) 
1"  8 UNC
(25 mm) 
15/8"
(41 mm) 
75.8 kips
(337 kN) 
63.6 kips
(283 kN) 
37.9 kips
(168 kN) 
12.9 kips
(57.4 kN) 
11/4"  7 UNC
(32 mm) 
2"
(51 mm) 
121 kips
(539 kN) 
102 kips
(453 kN) 
60.6 kips
(269 kN) 
20.6 kips
(91.6 kN) 
11/2"  6 NC
(38 mm) 
21/2"
(65 mm) 
176 kips
(781 kN) 
148 kips
(656 kN) 
87.8 kips
(390 kN) 
29.9 kips
(133 kN) 




These loads are valid where embedment is sufficient to assure steel failure; that is concrete shear cone strength is greater than steel strength.
(1) Allowable Simple Shear load per AISC Table 1D.
(2) Minimum ultimate static tension values based on physicals of ASTM A193 Grade B7 bolting material having 125,000 PSI minimum ultimate strength. 



Structural Properties
Yield
Stress

Ultimate
Stress

Elongation in
20 Bar Diameters

Reduction
of Area

105 KSI
(723 mPa)

125 KSI
(861 mPa)

16%

50%









Stainless S9 Undercut Anchor  ASTM A193 304 B8 & 316 B8M Class I 



Stud
Diameter 
Drill
Hole
Diameter 
Minimum
Ultimate Strength
(FpuA) (2) 
Minimum
Yield
Strength 
Allowable
Tension
.6 (FpuA) 
Allowable
Simple Shear
.17 (FpuA) (1) 
1/4"  20 UNC
(6.4 mm) 
5/8"
(16 mm) 
2.39 kips
(10.6 kN) 
0.95 kips
(4.2 kN) 
0.570 kips
(2.54 kN) 
0.405 kips
(1.81 kN) 
3/8"  16 UNC
(10 mm) 
7/8"
(22 mm) 
5.81 kips
(25.8 kN) 
2.32 kips
(10.3 kN) 
1.39 kips
(6.18 kN) 
0.988 kips
(4.39 kN) 
1/2"  13 UNC
(12 mm) 
7/8"
(22 mm) 
10.6 kips
(47.3 kN) 
4.26 kips
(18.9 kN) 
2.56 kips
(11.5 kN) 
1.81 kips
(8.05 kN) 
5/8"  11 UNC
(16 mm) 
11/8"
(29 mm) 
16.9 kips
(75.4 kN) 
6.78 kips
(30.2 kN) 
4.07 kips
(18.1 kN) 
2.88 kips
(12.8 kN) 
3/4"  10 UNC
(20 mm) 
11/8"
(29 mm) 
25.1 kips
(111 kN) 
10.0 kips
(44.6 kN) 
6.00 kips
(26.7 kN) 
4.26 kips
(18.9 kN) 
1"  8 UNC
(25 mm) 
15/8"
(41 mm) 
45.5 kips
(202 kN) 
18.2 kips
(80.9 kN) 
10.9 kips
(48.5 kN) 
7.73 kips
(34.6 kN) 
11/4"  7 UNC
(32 mm) 
2"
(51 mm) 
72.7 kips
(323 kN) 
29.1 kips
(129 kN) 
17.5 kips
(77.8 kN) 
12.4 kips
(55.0 kN) 
11/2"  6 NC
(38 mm) 
21/2"
(65 mm) 
105 kips
(469 kN) 
42.2 kips
(188 kN) 
25.3 kips
(112 kN) 
17.9 kips
(79.5 kN) 




These loads are valid where embedment is sufficient to assure steel failure; that is concrete shear cone strength is greater than steel strength.
(1) Allowable Simple Shear load per AISC Table 1D. 



Structural Properties
Yield
Stress

Ultimate
Stress

Elongation in
20 Bar Diameters

Reduction
of Area

30 KSI
(207 mPa)

75 KSI
(517 mPa)

30%

50%









Stainless S9 Undercut Concrete Anchor  ASTM A193 304 B8 Class II 



Stud
Diameter 
Drill
Hole
Diameter 
Minimum
Ultimate Strength
(FpuA) (2) 
Minimum
Yield
Strength 
Allowable
Tension
.6 (FpuA) 
Allowable
Simple Shear
.17 (FpuA) (1) 
1/4"  20 UNC
(6.4 mm) 
5/8"
(16 mm) 
3.98 kips
(17.7 kN) 
3.18 kips
(14.1 kN) 
1.91 kips
(8.50 kN) 
0.670 kips
(2.98 kN) 
3/8"  16 UNC
(10 mm) 
7/8"
(22 mm) 
9.69 kips
(43.1 kN) 
7.75 kips
(34.5 kN) 
4.65 kips
(20.7 kN) 
1.65 kips
(7.33 kN) 
1/2"  13 UNC
(12 mm) 
7/8"
(22 mm) 
17.7 kips
(78.9 kN) 
14.2 kips
(63.1 kN) 
8.52 kips
(37.9 kN) 
3.01 kips
(13.4 kN) 
5/8"  11 UNC
(16 mm) 
11/8"
(29 mm) 
28.2 kips
(126 kN) 
22.6 kips
(101 kN) 
13.6 kips
(60.5 kN) 
4.79 kips
(21.3 kN) 
3/4"  10 UNC
(20 mm) 
11/8"
(29 mm) 
41.8 kips
(186 kN) 
33.4 kips
(146 kN) 
20.0 kips
(88.96 kN) 
7.10 kips
(31.6 kN) 
1"  8 UNC
(25 mm) 
15/8"
(41 mm) 
69.7 kips
(310 kN) 
48.4 kips
(215 kN) 
29.0 kips
(129 kN) 
11.8 kips
(52.9 kN) 
11/4"  7 UNC
(32 mm) 
2"
(51 mm) 
102 kips
(453 kN) 
63.0 kips
(280 kN) 
37.8 kips
(167 kN) 
17.3 kips
(77.5 kN) 
11/2"  6 NC
(38 mm) 
21/2"
(65 mm) 
141 kips
(625 kN) 
70.2 kips
(312 kN) 
42.1 kips
(187 kN) 
25.1 kips
(112 kN) 




These loads are valid where embedment is sufficient to assure steel failure; that is concrete shear cone strength is greater than steel strength.
(1) Allowable Simple Shear load per AISC Table 1D. 



Structural Properties
Stud
Diameter 
Yield
Stress

Ultimate
Stress

Elongation in
20 Bar Diameters

Reduction
of Area

1/4"  3/4"
(6.4  20 mm) 
100 KSI
(207 mPa)

125 KSI
(517 mPa)

12%

35%

1"
(25 mm) 
80 KSI
(552 mPa)

115 KSI
(793 mPa)

15%

11/4"
(32 mm) 
65 KSI
(448 mPa)

105 KSI
(724 mPa)

20%

11/2"
(38 mm) 
50 KSI
(375 mPa)

100 KSI
(670 mPa)

28%

45%









Stainless S9 Undercut Concrete Anchor  ASTM A193 316 B8M Class II 



Stud
Diameter 
Drill
Hole
Diameter 
Minimum
Ultimate Strength
(FpuA) (2) 
Minimum
Yield
Strength 
Allowable
Tension
.6 (FpuA) 
Allowable
Simple Shear
.17 (FpuA) (1) 
1/4"  20 UNC
(6.4 mm) 
5/8"
(16 mm) 
3.50 kips
(15.6 kN) 
3.05 kips
(13.6 kN) 
1.83 kips
(8.14 kN) 
0.595 kips
(2.65 kN) 
3/8"  16 UNC
(10 mm) 
7/8"
(22 mm) 
8.53 kips
(37.9 kN) 
7.44 kips
(33.1 kN) 
4.46 kips
(20.0 kN) 
1.45 kips
(6.45 kN) 
1/2"  13 UNC
(12 mm) 
7/8"
(22 mm) 
15.6 kips
(69.4 kN) 
13.6 kips
(60.6 kN) 
8.16 kips
(36.3 kN) 
2.65 kips
(11.8 kN) 
5/8"  11 UNC
(16 mm) 
11/8"
(29 mm) 
24.9 kips
(110 kN) 
21.7 kips
(96.5 kN) 
13.0 kips
(57.8 kN) 
4.23 kips
(18.8 kN) 
3/4"  10 UNC
(20 mm) 
11/8"
(29 mm) 
36.7 kips
(163 kN) 
32.1 kips
(143 kN) 
19.3 kips
(85.8 kN) 
6.24 kips
(27.8 kN) 
1"  8 UNC
(25 mm) 
15/8"
(41 mm) 
60.6 kips
(269 kN) 
48.5 kips
(216 kN) 
29.1 kips
(129 kN) 
10.3 kips
(45.8 kN) 
11/4"  7 UNC
(32 mm) 
2"
(51 mm) 
92.0 kips
(409 kN) 
63.0 kips
(280 kN) 
37.8 kips
(168 kN) 
15.8 kips
(70.3 kN) 
11/2"  6 NC
(38 mm) 
21/2"
(65 mm) 
126 kips
(562 kN) 
70.2 kips
(312 kN) 
42.1 kips
(187 kN) 
21.5 kips
(95.6 kN) 




These loads are valid where embedment is sufficient to assure steel failure; that is concrete shear cone strength is greater than steel strength.
(1) Allowable Simple Shear load per AISC Table 1D. 



Structural Properties
Stud
Diameter 
Yield
Stress

Ultimate
Stress

Elongation in
20 Bar Diameters

Reduction
of Area

1/4"  3/4"
(6.4  20 mm) 
96 KSI
(662 mPa)

110 KSI
(759 mPa)

15%

45%

1"
(25 mm) 
80 KSI
(552 mPa)

100 KSI
(670 mPa)

20%

11/4"
(32 mm) 
65 KSI
(448 mPa)

95 KSI
(655 mPa)

25%

11/2"
(38 mm) 
50 KSI
(375 mPa)

90 KSI
(621 mPa)

30%
















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