S-BT Threaded Fastener Specification

page 74 Specifications
AWSD1.1/D1.1M:2015
ItisrecommendedtousethefollowingdesignS-Ncurverespectivelystress
categorytermed“S-BT”giveninTable4andFigure2fortheconstructional
detail“SteelbasematerialwithHiltiS-BTscrew-inthreadedstuds”.
Universität Stuttgart
Institut für Konstruktion und Entwurf
Schwerpunkte: Stahlbau, Holzbau und Verbundbau
Prof. Dr.-Ing. Ulrike Kuhlmann
2017-06-30 S-BT Fatigue Page 35
9.2.2 Recommendation of a design S-N curve for AWS D1.1
AWS D1.1/D1.1M:2015 includes 8 fatigue categories A to F for redundant non-tubular structures
with corresponding S-N curves, see
Table 7.1. The transition point to the constant amplitude
fatigue limit (CAFL) depends on the fatigue category. In general the slope is m = 3 as typical for
welded details. However, detail category F has a slope of m = 6.
Based on the statistical evaluation of the Hilti S-BT fatigue test data according to
Table 9.1 an
additional stress category “S-BT” is proposed having a uniform slope of m = 5, see following
Table 9.2 and Figure 31. A constant amplitude fatigue limit (CALF) at N = 5∙10
6
cycles, result-
ing in a threshold value of F
TH
= 87.0 MPa is recommended.
Table 9.2. AWS S-N curves and new proposed S-N curve for Hilti S-BT fastener
Stress m C
f
C
f
x 329 F
TH
Category
[-] for [ksi] for [MPa] [ksi] [MPa]
A
3.0 250 x 10
8
8.225 x 10
12
23.9 165.0
B
3.0 120 x 10
8
3.948 x 10
12
16.0 110.0
B'
3.0 61 x 10
8
2.007 x 10
12
12.0 83.0
C
3.0 44 x 10
8
1.448 x 10
12
10.0 69.0
D
3.0 22 x 10
8
7.238 x 10
11
7.0 48.0
E
3.0 11 x 10
8
3.619 x 10
11
4.5 31.0
E'
3.0 39 x 10
8
1.283 x 10
11
2.6 18.0
F
6.0 150 x 10
10
1.650 x 10
17
8.0 55.0
S-BT 5.0 6065 x 10
10
1.995 x 10
16
12.6 87.0
10
100
10.000 100.000 1.000.000 10.000.000
Number of cycles N [-]
Nominal stress range  [N/mm
2
]
300
200
100
Hilti S-BT fastener
(correctly installed)
Hilti S-BT fastener
(installed and removed)
proposed design S-N curve
400
50
500
A
10
70
20



t
Hilti S-BT
B
B’
C
D
E’
E
F
(m=6)
AWS
category
w
elded stud
m =5
1
Figure 31. Comparison of Hilti S-BT fatigue test data with AWS D1.1:/D1.1M:2015 fatigue categories
and new proposed fatigue stress category “S-BT” for Hilti S-BT fastener
Figure2:ComparisonofHiltiS-BTfatiguetestdatawithAWSD1.1:/D1.1M:2015
fatiguecategoriesandnewproposedfatiguestresscategory“S-BT”forHiltiS-BT
fastener
Universität Stuttgart
Institut für Konstruktion und Entwurf
Schwerpunkte: Stahlbau, Holzbau und Verbundbau
Prof. Dr.-Ing. Ulrike Kuhlmann
2017-06-30 S-BT Fatigue Page 35
9.2.2 Recommendation of a design S-N curve for AWS D1.1
AWS D1.1/D1.1M:2015 includes 8 fatigue categories A to F for redundant non-tubular structures
with corresponding S-N curves, see
Table 7.1. The transition point to the constant amplitude
fatigue limit (CAFL) depends on the fatigue category. In general the slope is m = 3 as typical for
welded details. However, detail category F has a slope of m = 6.
Based on the statistical evaluation of the Hilti S-BT fatigue test data according to
Table 9.1 an
additional stress category “S-BT” is proposed having a uniform slope of m = 5, see following
Table 9.2 and Figure 31. A constant amplitude fatigue limit (CALF) at N = 5∙10
6
cycles, result-
ing in a threshold value of F
TH
= 87.0 MPa is recommended.
Table 9.2. AWS S-N curves and new proposed S-N curve for Hilti S-BT fastener
Stress m C
f
C
f
x 329 F
TH
Category
[-] for [ksi] for [MPa] [ksi] [MPa]
A
3.0 250 x 10
8
8.225 x 10
12
23.9 165.0
B
3.0 120 x 10
8
3.948 x 10
12
16.0 110.0
B'
3.0 61 x 10
8
2.007 x 10
12
12.0 83.0
C
3.0 44 x 10
8
1.448 x 10
12
10.0 69.0
D
3.0 22 x 10
8
7.238 x 10
11
7.0 48.0
E
3.0 11 x 10
8
3.619 x 10
11
4.5 31.0
E'
3.0 39 x 10
8
1.283 x 10
11
2.6 18.0
F
6.0 150 x 10
10
1.650 x 10
17
8.0 55.0
S-BT 5.0 6065 x 10
10
1.995 x 10
16
12.6 87.0
10
100
10.000 100.000 1.000.000 10.000.000
Number of cycles N [-]
Nominal stress range  [N/mm
2
]
300
200
100
Hilti S-BT fastener
(correctly installed)
Hilti S-BT fastener
(installed and removed)
proposed design S-N curve
400
50
500
A
10
70
20



t
Hilti S-BT
B
B’
C
D
E’
E
F
(m=6)
AWS
category
w
elded stud
m =5
1
Figure 31. Comparison of Hilti S-BT fatigue test data with AWS D1.1:/D1.1M:2015 fatigue categories
and new proposed fatigue stress category “S-BT” for Hilti S-BT fastener
Universität Stuttgart
Institut für Konstruktion und Entwurf
Schwerpunkte: Stahlbau, Holzbau und Verbundbau
Prof. Dr.-Ing. Ulrike Kuhlmann
2017-06-30 S-BT Fatigue Page 44
10.2.3 AWS D1.1/D1.1M:2015
It is recommended to use the following design S-N curve respectively stress category termed
“S-BT” given in
Table 10.2 for the constructional detail “Steel base material with Hilti S-BT
screw-in threaded studs”.
Table 10.2. Recommendation of fatigue S-N curve and stress category according to AWS D1.1:2015
Description and requirements
Stress
Category
Constant
C
f
ksi [MPa]
Threshold
F
TH
ksi [MPa]
Slope
m
Potential
crack
initiation
Illustrative
Example
Hilti S-BT screw-in stainless and
carbon steel threaded studs with pre-
drilled hole in structural steel base
material.
Imperfect fastener installations as e.g.
overwound or pulled-out fasteners are
covered.
 to be calculated by the gross
cross-section.
Installation, static loading and spacing
of fasteners only in accordance with
the requirements given in [1] or [2].
Plate thickness t  3 mm.
Steel base material up to yield
strength 355 MPa.
S-BT
6065x10
10
[1.995x10
16
]
12.6
[87.0]
5.0
At the edge
or tip of the
pre-drilled
hole
[1] Hilti S-BT screw-in threaded studs. Specification Binder, Edition 01/2017
[2] Hilti Direct Fastening Technology Manual. Edition 12/2016. S-BT product pages.
10.2.4 ABS:2014
It is recommended to use the following S-N curve respectively stress category termed “S-BT”
given in
Table 10.3 for the constructional detail “Steel base material with Hilti S-BT screw-in
threaded studs”.
Table 10.3. Recommendation of fatigue S-N curve and fatigue class according to ABS-(A):2014
Description and notes on mode
of failure
Class Explanatory comments
Example including
failure modes
Hilti S-BT screw-in stainless and carbon
steel threaded studs with pre-drilled hole
in structural steel base material.
Imperfect fastener installations as e.g.
overwound or pulled-out fasteners are
covered.
Potential crack initiation at the edge or
tip of the pre-drilled hole.
S-BT
 to be calculated by the gross
cross-section.
Installation, static loading and
spacing of fasteners only in ac-
cordance with the requirements
given in [1] or [2].
Plate thickness t  3 mm.
Steel base material up to yield
strength 355 MPa.
Parameter of design S-N curve class S-BT
Curve A m r N
Q
S
Q
Class for [MPa]
units
for [ksi]
units
for [MPa]
units
for [ksi]
units
for [MPa]
units
for [ksi]
units
S-BT 1.995
x10
16
1.28x10
12
5.0 1.995x10
16
1.28x10
12
5.0 1.0x10
7
72.4 10.50
[1] Hilti S-BT screw-in threaded studs. Specification Binder, Edition 01/2017
[2] Hilti Direct Fastening Technology Manual. Edition 12/2016. S-BT product pages.
Table4:RecommendationoffatigueS-Ncurveandstresscategoryacc.toAWS
D1.1:2015