Faculty of Built Environment, Department of Structural Engineering
Research Centre of Metal Structures, Seinäjoki, Hämeenlinna
METNET, Aarhus 2011 1
EXPERIMENTS OF END PLATE JOINTS IN AMBIENT AND
FIRE CONDITIONS UNDER BIAXIAL BENDING
RESEARCH TEAM: Hilkka Ronni, Henri Perttola, Markku Heinisuo, Keijo Fränti
PRESENTATION: Keijo Fränti
Tampere University of Technology
Research Centre of Metal Structures,
Frami, Kampusranta 9 C, FI-60320 Seinäjoki, Finland
Faculty of Built Environment, Department of Structural Engineering
Research Centre of Metal Structures, Seinäjoki, Hämeenlinna
METNET, Aarhus 2011 2
FOUR TEST DESCRIBED …
▪ Two pairs of tests (four tests) on splice joints for (RHS) tubes are described.
All the joints were under biaxial bending.
▪ In a pair, two similar joints were tested: one in room temperature and
another one at elevated temperature (in furniture under ISO 834 standard fire).
▪ These four tests belong to the larger test series (of 29 tests) through which the
applicability of the component method for three dimensional (3D) analysis
is studied.
▪ The preliminary results of the ongoing research on the 3D component method
are presented in the case of the described tests.
Faculty of Built Environment, Department of Structural Engineering
Research Centre of Metal Structures, Seinäjoki, Hämeenlinna
500
20
500
CFRHS 250x150x10
20
tpn = 10 / 20 /
verticalsupport
35
plate 20 x 295 x 280
Holes D22
v
Mid section
35
CFRHS 250x150x10
TE1, TE3
End sections
end plate tp x 290 x 390
295
a8
F
end plate + loading shelf
28
01
0
20
10
10
30
230
30
30
30
330
70
70
390
290
8 8
8
4
DET A
A
METNET, Aarhus 2011 3
JOINT TESTS: SPECIMEN
BOLTS + WASHERS + NUTS M20-10.9
END PLATE JOINT (FLANGED SPLICE)
Steel S355
TUBE: CFRHS 250x150x10 - S355
500
20
500
CFRHS 250x150x10
20
tpn = 10 / 20 /
verticalsupport
35
plate 20 x 295 x 280
Holes D22
v
Mid section
35
CFRHS 250x150x10
TE1, TE3
End sections
end plate tp x 290 x 390
295
a8
F
end plate + loading shelf
28
01
0
20
10
10
30
230
30
30
30
330
70
70
390
290
8 8
8
4
DET A
A
Test pairs
tpn (nominal)
[mm]
tp (measured)
[mm]
ReH
[MN/m2 ]
Rm
[MN/m2]
A5
%
TE1 and TE1* 10 11.0 429 582 24
TE3 and TE3* 20 20.3 380 564 26
* = SPECIMEN IN FIRE TEST
Similar joints in room temperature and in fire tests, dimensions and properties of end plates:
Faculty of Built Environment, Department of Structural Engineering
Research Centre of Metal Structures, Seinäjoki, Hämeenlinna
METNET, Aarhus 2011 4
SPECIMEN
HINGE
BALL JOINT
HYDRAULIC JACK
BEARING
ROLLER
SHELF (welded to the specimen)
LOAD CELL
TESTING ARRANGEMENTS (T=20 °C), BIAXIAL BENDING:
35 °
35 °
F
TRANSVERSE MOVEMENT IS ALLOWED AT MID SPAN!
Faculty of Built Environment, Department of Structural Engineering
Research Centre of Metal Structures, Seinäjoki, Hämeenlinna
METNET, Aarhus 2011 5
▪ PROCEDURE: LOAD IS INCREASED (IN RATE 0.1kN/s) UP TO FAILURE
DIMENSIONS OF THE SPECIMEN (=TUBES
AND THEIR SPLICE) ARE SELECTED IN
SUCH A WAY THAT THE DEFORMATIONS
WERE CONCENTRATED ON THE JOINT!
MR = PL/4
θ = 2(v - vb,el ) /L
TEST RESULTS (T = 20 °C), BIAXIAL BENDING:
▪ MAIN INTEREST IS IN THE ROTATIONAL BEHAVIOUR OF THE JOINT
Moment-rotation
0
20
40
60
80
100
0 20 40 60 80 100 120 140 160
Q [mrad]
M [
kNm
]
TE3, t=20mm
TE1, t=10mm
Faculty of Built Environment, Department of Structural Engineering
Research Centre of Metal Structures, Seinäjoki, Hämeenlinna
METNET, Aarhus 2011 6
FAILURE MODES, T = 20 °C
TE1: THIN ENDPLATE (t = 11.0 mm): TE3: THICK END PLATE (t = 20.3 mm):
VISBLE NECKING IN
THE LOWEST BOLT !
EC3: MODE I (COMPLETE YIELDING
OF THE FLANGE) OK!! EC3: MODE II (BOLT FAILURE WITH
YIELDING OF THE FLANGE) OK!!
LOWEST BOLT
Faculty of Built Environment, Department of Structural Engineering
Research Centre of Metal Structures, Seinäjoki, Hämeenlinna
METNET, Aarhus 2011 7
K1, K2, K3 and K4
Chain
Threaded round barThreaded round bar
Transducer S1 Transducer S2
K2K2
K2
K1
K3
K4K4
Chain
Square hollow sections (SHS):
Hydraulic JackHydraulic Jack
Tachymeters
K2K2
K3
K3
K2
K1
Furnace
Tested specimen
TESTING ARRANGEMENT, FIRE TESTS:
510
CFRHS 250x150x12.5
4M20 (10.9)
CFRHS 250x150x12.5
11 or 20
20
FF
Rigid Support
510
LOAD WAS MAINTAINED WHILE THE
SPECIMEN WAS HEATED
(TRANSIENT TEST)!
NOTE: Tests in room temperature and in fire
were both three point (biaxial) bending tests!
gas burner
Faculty of Built Environment, Department of Structural Engineering
Research Centre of Metal Structures, Seinäjoki, Hämeenlinna
METNET, Aarhus 2011 8
1 2
34
11
12
13
14
5 7
6
8
910
0
100
200
300
400
500
600
700
800
900
0 5 10 15 20 25 30 35 40
Tem
pera
ture
[°C
]
Time [min]
TE1*
Furnace
ISO834
Thermocouple average 1-4, in the middle of the side
Thermocouple average 5-10, in the corners
Thermocouple average 11-14, in the bolts
A/V=50
A/V=100
TEST TE1: STANDARD FIRE IN FURNACE TEMPERATURES OF FLANGES AND BOLTS
13 min: 20 min: 26 min:
TEST IS OVER (few minutes after failure) TE1*: SUSTAINED LOAD LEVEL M = 0.16*Mu, T = 20°C
FAILURE WHEN T = Tcr = 800 ° C
Faculty of Built Environment, Department of Structural Engineering
Research Centre of Metal Structures, Seinäjoki, Hämeenlinna
METNET, Aarhus 2011 9
0
100
200
300
400
500
600
700
800
900
0 5 10 15 20 25 30 35 40
Tem
pera
ture
[˚C
]
Time [min]
TE3*
Furnace
ISO834
Thermocouple average 1-4, in the middle of the side
Thermocouple average 5-10, in the corners
Thermocouple average 11-14, in the bolts
A/V=50
A/V=100
FIRE TEST TE3*
SUSTAINED LOAD LEVEL: M = 0.16*Mu, T=20°C
Tkr = 655 °C
Faculty of Built Environment, Department of Structural Engineering
Research Centre of Metal Structures, Seinäjoki, Hämeenlinna
METNET, Aarhus 2011 10
FAILURE MODES IN FIRE TESTS
M = 0.23*Mu, T=20°C M = 0.16*Mu, T=20°C
FAILURE MODE: EXCESSIVE DEFORMATIONS
= FLANGÈ YIELDING + BOLT EXTENSION
FAILURE MODE: FAILURE OF THREADS IN
THE LOWEST BOLT OF THE JOINT
(completely different failure mode than in
test TE3 arranged in room temperature)
Tcr, average = 800 °C Tcr , average= 655 °C
TE1: THIN ENDPLATE (t = 11 mm) TE3: THICK ENDPLATE (t = 20,3 mm)
Faculty of Built Environment, Department of Structural Engineering
Research Centre of Metal Structures, Seinäjoki, Hämeenlinna
METNET, Aarhus 2011 11
0
10
20
30
40
50
60
70
80
0 100 200 300 400 500 600 700 800 900
Mo
men
t [k
Nm
]
Temperature [°C]
Moment resistance versus temperature, TE1*
TE1*, fire test
Componentmethod (method 2)
TE1, room temperature test
0
10
20
30
40
50
60
70
80
90
100
0 100 200 300 400 500 600 700 800 900
Mo
men
t [k
Nm
]
Temperature [°C]
Moment resistance versus temperature, TE3*
Componentmethod (red. factor for carbon steel)
Componentmethod (red. factor for bolts)
TE3*, fire test
TE3, room temperature test
COMPONENT METHOD, FIRE TESTS (SIMPLIFIED RESULTS)
ON SAFE SIDE BOTH AT ROOM
TEMPERATURES AND IN FIRE
NOTE: Excessive deformation of the end
plate in the decisive role in both cases!
ON SAFE SIDE AT LOW TEMPERATURES
(reductions according to carbon steel)
ON SAFE SIDE AT HIGH TEMPERATURES
(redaction according to bolts) !
NOTE1: Different failure modes for the
joint in ambient and fire conditions .
NOTE2: In fire, the behaviour of the bolt
is in the decisive role!
Faculty of Built Environment, Department of Structural Engineering
Research Centre of Metal Structures, Seinäjoki, Hämeenlinna
METNET, Aarhus 2011 12
SUMMARY
MORE 3D JOINT TESTS ARE NEEDED IN FUTURE!
1) No tests on the bolted end plate steel joints in biaxial bending were found in
literature … the tests described were ”pilot tests” in their character!
NOTE1: Some weak axis bending tests has been arranged in ambient conditions
NOTE2: In general, there is lack of joint tests in fire (quite new research area!)
3) Remarks concerning the ongoing research on 3D component method:
▪ The preliminary results on the applicability of the 3D component method are
quite encouraging for the joints under biaxial bending in ambient conditions.
▪ ”Joints in fire” is more challenging case than ”joints in room temperature”!
2) Observations based on four tests were described :
▪ The failure modes of two similar joints may be different in room temperatutre and in fire!
Faculty of Built Environment, Department of Structural Engineering
Research Centre of Metal Structures, Seinäjoki, Hämeenlinna
METNET, Aarhus 2011 13
THAT’S IT, THANK YOU!
SPECIMEN UPSIDE DOWN ON LABORATORY FLOOR AFTER ROOM TEMPERATURE TEST TE3, Pmax ~ 400 kN (Mmax ~ 100kN)
FEM SIMULATION BY ABAQUS: