Determination of PinPin-bearing Strength for
the Design of Bolted Connections with
Standard Pultruded Profiles
Behrouz Zafari¹ & J. Toby Mottram²
Civil Research Group, School of Engineering,
University of Warwick, UK
5th International Conference on FRP Composites in Civil Engineering
FRP C
it i Ci il E i
i
th
th
September 27 ‐29 , 2010 Beijing, China
1 PhD Student & speaker
2 Reader
2
Bearing Strength and Bolted Connections
1.00
Content of paper:
method for determining pinb i strength.
bearing
t
th
• Strength variation with
orientation of connection
force.
Normalised strength
• WU (Warwick University) test
FRP pin-bearing
0.95
0.90
0.85
0 80
0.80
0.75
0.70
0.65
0
15
30
45
60
Orientation (degree)
75
90
1
3
Types of Bolted Connections
and Joints
Design of frame joints, such as the
web cleated type shown on top-right
web-cleated
top right
(classify
as
simple
using
the
principles in BS EN 1993-1-8:2006),
with
the
design
of
plate-to-plate
connections, such as there is in each
of
the
cleat
legs
and
bracing
members (bottom-right).
4
Plate--to
Plate
to--plate Resistances
Distinct modes of failure (single-bolted connections)
or
e1
dn
2e2
(a)
(b)
(c)
(d)
(a) bearing, (b) net-tension, (c) shear-out, (d) cleavage
2
Strength formula – Bearing mode of failure
Rbr  t d Fbr
5
Compression load
t is thickness of FRP
d is diameter of bolt
Fbr is pin-bearing strength for
the orientation of material to the
resultant connection force.
 = 0° (or longitudinal) when
direction of pultrusion is aligned
with connection force.
WU pin-bearing strength test rig
and 100x 100 mm specimen size
Strength formula – Bearing mode of failure
Specimens from web of
203 × 203 × 9.53 mm Wide Flange
section Creative Pultrusions Inc.
section.
Inc
Pultex 1525 series with a
thermoset polyester resin.
6
Bearing failure - 0o specimen
Test results for 0°, 45° and 90˚
material orientations, at room
temperature.
3
7
Pin--bearing Strength test results
Pin
Longitudinal web material,F 
br
Mean web thickness, t (mm)
9.16
9.14
9.12
9.14
Mean notch diameter, dn (mm)
11.8
14.8
20.9
27.9
Mean pin diameter, d (mm)
9.7
12.2
18.8
25.4
Mean clearance, dn - d (mm)
1.9
2.6
2.1
2.5
No. of nominally identical specimens
11
11
11
11
136
Mean pin-bearing strength, (N/mm2)
188
170
154
SD (N/mm2)
6.2
9.1
12.7
14.8
CV (%)
3.3
5.3
8.4
10.9
Characteristic value* (N/mm2)
177
155
133
111
Mean d/t ratio
1.06
1.34
2.05
2.78
di ti
direction
90o
0o
Note: * Characteristic value = Mean – 1.72SD
(Batches of 10)
Pin--bearing Strength Test Results
Pin
8
200
Transverse (90o) direction
Pin-bearing stress (N/mm
m2)
175
• Load-stroke curves
are virtually linear for
stroke to 0.8 mm.
150
125
• For hole diameters of
12 and 15 mm there
is a higher load after
initial failure.
100
75
Hole diameter (mm)
50
12
15
25
21
28
• For hole diameter 21
and 28 mm the
bearing failure is
brittle.
0
0.0
0.5
1.0
1.5
2.0
2.5
Stroke (mm)
4
9
Pin--bearing Strength Test Results
Pin
200
For nominal hole diameter of 28 mm (d/t = 2.78)
Pin-bearing stress (N/m
mm2)
175
150
Fbr / Fbr
125
0°
100
45º modulus of elasticity
45°
90°
75
= 1.13
is 11.2 kN/mm2 ;
1.12 higher than in the
50
90o direction.
25
Two ratios the same.
0
0.0
0.5
1.0
1.5
Stroke (mm)
2.0
2.5
Pin--bearing Strength Test Results
Pin
10
Characteristic pin bearring strength
(N/mm2)
200
175
Hole clearance is 1.9 mm or larger
150
0°
45°
125
90°
100
75
50
25
0
1
1.5
d/t
2
2.5
3
(Ratio of pin diameter-to-material thickness)
Reduces between 50 and 60% on increasing pin diameter from 9.7 to 25.4 mm.
5
11
Concluding Remarks
•
Warwick University pin-bearing strength test method has the potential to
be developed into a standard test method.
•
Minimum characteristic strength values are 111 N/mm2 (0o) (CV @ 11%),
2 (45o) (CV @ 4%)
2 (90o) (CV @ 6
111 N/mm
N/
4%), and
d 97 N/mm
N/
6.6%).
6%)
•
Characteristic strengths are very different (and unsafe) from 206 N/mm2 for
0o, and 124 N/mm2 for 90o given in Creative Pultrusions’ design manual.
•
Pin-bearing strength reduces with increase in the ratio of the pin diameterto-material thickness and standard test methods do not account for this.
•
Further series of tests are required to establish design strengths for
conditions found in practice over the life of pultruded structures.
5th International Conference on Advanced Composites
p
in Construction (ACIC 2011)
University of Warwick
6 - 8th September 2011
www.acic-conference.com
Email: B.Zafari@warwick.ac.uk
2010
6