BEHAVIOUR OF AXIALLY LOADED STRUCTURAL BOLTING ASSEMBLIES...
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BEHAVIOUR OF AXIALLY LOADED STRUCTURAL BOLTING ASSEMBLIES IN FIRE Lucy Johnson (1), Eric Palmiere (1), Richard Thackray (1), Ian Burgess (2), Buick Davison (2) (1) Department of Materials Science and Engineering (2) Department of Civil and Structural Engineering StiFF 09/04/2013
Transcript of BEHAVIOUR OF AXIALLY LOADED STRUCTURAL BOLTING ASSEMBLIES...
BEHAVIOUR OF AXIALLY LOADED
STRUCTURAL BOLTING
ASSEMBLIES IN FIRE
Lucy Johnson (1), Eric Palmiere (1), Richard Thackray (1),
Ian Burgess (2), Buick Davison (2)
(1) Department of Materials Science and Engineering
(2) Department of Civil and Structural Engineering
StiFF 09/04/2013
Outline
Importance
Structural Bolts
Experimental
Material Testing
Finite Element Modelling
Bolt Assembly Testing
Summary and Conclusions
Importance
Importance
1. Kirby, B.R., The behaviour of high-strength grade 8.8 bolts in fire. Journal of Constructional Steel Research, 1995. 33(1-2): p. 3-38.
2. Gonzalez, F. and J. Lange, Behaviour of Galvanized High Strength Grade 10.9 Bolts under Fire Conditions. 2009: p. 908-915.
3. Hu, Y., et al. Comparative study of the behaviour of BS 4190 and BS EN ISO 4014 bolts in fire. 2007.
Structural Bolts
M20 x 90 x Bolt =
M20 x 10 Nut =
8.8 SB
SB
Fu,nom = 800 Mpa
Fy,nom = 640 MPa
Fy,nom = 1 GPa
Experimental
Experimental
ε
(min-1)
Turned-down bolt Bolt Assembly
v
(mm/s)*
Temperature (˚C) v
(mm/s)**
Temperature (˚C)
20 550 620 700 20 550 620 700
0.002 6.7x10-4 x x x x 2.1x10-3 x x - x
0.01 3.3x10-4 x x x x 1.0x10-2 x x - x
0.02 6.7x10-3 x x x x 2.1x10-2 x x - x
* Based on a 20 mm gauge length where v=ε.L0
** Based on a 62 mm gauge length where v=ε.L0
Constant strain-rate to failure to measure ultimate strain
Material Testing
308 HV 243 HV
242 HV
Min = 255 HV
Material Testing
Decreasing
strength
Increasing
ductility
Material Testing
Material Testing
Material Testing
Finite Element Modelling
1) Temperature and strain rate
dependant material properties
2) Geometry (based on three
cross-sections)
Thread Tolerance
Material Properties
Assembly Tests
Strain measured at ends of
gauge length = 62 mm (necking
failure only)
Displacement measurement at
an area of high contrast
Assembly Tests
Assembly Tests
Assembly Tests
x
Assembly Tests
x
Assembly Tests
x
Assembly Tests
x
Assembly Tests
Summary and Conclusions
Microstructural variations exist which
affect stress-strain behaviour and
failure mode at ambient temperature
Elevated temperature properties are
not influenced by start microstructure
Optimum heat treatment?
