COMPFIRE

Robustness of Connections to Robustness of Connections to Composite

Columns in Fire

A European (RFCS) Collaborative Project

Joint types

Work packages

• WP1: Joint thermal behaviour and modelling

Connections to composite columns

• Reverse-channel connections to concrete-filled tubes

• End-plate connections to partially-encased H-sections

• WP1: Joint thermal behaviour and modelling

• WP2: Component behaviour

• WP3: Component-based joint modelling

• WP4: Fire tests on sub-frames

• WP5: Integrated FE modelling

• WP6: Demonstration fire tests

• WP7: Development of joint design guidance

Who’s involved?

PT University of Coimbra

CZ Czech Technical University, Prague

CZ Desmo AS Ltd

SE Luleå University of Technology

UK University of Manchester

UK University of Sheffield

UK Corus Ltd

Planned experimental work

� COMPFIRE will include several sets of tests to obtain information on connection behaviour, to validate numerical and analytical analysis, and to demonstrate the impact of improved joint detailing on robustness of composite structures in fire.

� The tests are distributed between the partners as follows:

WP 1: Joint thermal behaviour (Manchester, Prague)

WP 2: Component behaviour (Sheffield, Manchester, Coimbra)

WP 4: Fire tests on sub-frame (Manchester, Coimbra)

WP 6: Demonstration full-scale fire tests (Prague)

Work Package 1

Joint thermal behaviour

• University of Manchester• University of Manchester• University of Coimbra

Work Package 1

Joint thermal behaviour

To establish temperature distribution in components of different types of protected and unprotected joints.

Partner Column Beam Joint type Fire curve

CFT 250x8

UB Reverse ISO 834

Th

eU

niv

ers

tyo

fM

an

ch

este

r

250x8circular

UB 305x165x40

Reverse channel

ISO 834(6 tests)

CFT 250x8 square

UB 305x165x40

Reverse channel

ISO 834(6 tests)

Partially encased

UB 305x165x40

End plateFin plate

ISO 834(12 tests)

Work Package 2

Component behaviour

• Luleå University of Technology• Luleå University of Technology• University of Coimbra• University of Sheffield• University of Manchester

WP2: Component behaviour

Sheffield tests

• 20 constant-temperature tests of isolated joints under combinations of axial/shear force and moment.

Manchester and Coimbra tests

• Components of reverse- channel and filled hollow section walls at ambient and elevated temperatures.

combinations of axial/shear force and moment.

• CFT and partially-encased columns.

• Change to existing test loading arrangement, keeping the axial, shear, BM the same in order to examine the performance of the reverse channel.

Luleå modelling

• Extensive FE calculations to analyse test data.

Objective of WP2

Simplified component models

• Develop and validate simplified models of component behaviour, linking temperature, component behaviour, linking temperature, force and deflection.

WP2 schedule

Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

Constant-temperature tests of joint

components to concrete-filled tubes

Constant-temperature tests of joint

components to partially encased

columns

Constant-temperature tests of isolated

joints under combinations of

Year 1 Year 2 Year 3Component behaviour

joints under combinations of

axial/shear forces and bending

moments

Extensive finite element analyses to

analyse test data

Develop simplified models of

component behaviour, linking

temperature-force-deflection

Prepare report on simplified structural

behaviour of components

Preliminary FEA: Flush endplate to H-column

Moment-rotation diagram

0

20

40

60

80

100

120

0.00 0.02 0.04 0.06 0.08 0.10

Mo

me

nt

[kN

m]

rotation [rad]

Preliminary FEA: Square tube with reverse channel connection

Moment-rotation diagram

0

5

10

15

20

25

30

35

0.00 0.01 0.02 0.03 0.04 0.05 0.06

Mo

men

t [k

Nm

]

rotation [rad]

Sheffield test programme

No. Column Temp Connection type Reason Comments

1 � 20 Fin plate Control set at

ambient temp.

(2 extremes)

Keep the loading

angle (55°)

constant for all

tests

2 � 20 [ (widest) UKPFC 230x90x32

3 � 20 Fin plate

4 � 20 [ (widest) UKPFC 230x90x32

5 � 550 Fin plate Repeat control set

at elevated

temperature

Keep the

temperature the

same for all tests

6 � 550 [ (widest) UKPFC 230x90x32

7 � 550 Fin plate

8 � 550 [ (widest) UKPFC 230x90x32

9 � 550 [ channel/tube width 2

UKPFC 200x90x30

Effect of

channel/tube width

Fin plate is one

extreme, full width

• 250x8 square /244.5x8 round tubes

• Thick beam endplate (20mm) to ensure channel is the weakest component

is the other. 10 � 550 [ channel/tube width 3

UKPFC 180x90x26

11 � 550 [ channel/tube width 2

UKPFC 200x90x30

12 � 550 [ channel/tube width 3

UKPFC 180x90x26

13 � 550 [ channel type 1 Examine type,

thickness &

width/depth ratio of

[ channel

Use [ channels

which are cut from

tubes

14 � 550 [ channel type 2

15 � 550 [ channel type 1

16 � 550 [ channel type 2

17 H 550 Direct To be tested the first – reuse existing

specimens so no fabrication is needed 18 H 650 Direct

19 H 550 [ (narrow) UKPFC 150x75x18 Use narrow [ to avoid excessive pulling

force on column flange20 H 650 [ (narrow) UKPFC 150x75x18

• M20 Grade 8.8 bolts (latest BS EN ISO standards)

• All beams -UB305x165x40

• Target completion date: 30th July 2010

Test setup

Furnace

Reaction frame

Load Jack

Dimensions of test specimens

Test specimens

Reinforcement of partially-encased column

� Designed to EC4

Partially-encased column

• Scheduled to start by end April 2010

Specimen in furnace

• Scheduled to start by end April 2010

Test measurement

Camera 3Furnace

Reaction frame• Forces measured by

strain gauges on bars

Camera 1: In front of the furnace to measure connection deformation

Camera 2: From rear facing central pin connecting loading bars to measure bar alignment

Camera 3: From top to measure connection deformation

Strain gauges

Camera 2Camera 1

Camera views of test setup

View from Camera 2

View from Camera 1

View from Camera 3

Image processing to trace displacement

• Step 1: Obtain the initial coordinates of the measuring points (Montivision Image Analyser)

• Step 2: Trace the movement of the movement of the measuring points (GeoPIV)

WP3: Component-based joint modelling

Component-based joint element

• University of Sheffield• University of Sheffield• Corus Ltd

The Component Method

• Separate the zones of fundamental behaviour (“components”) within a joint.

• Predict the Force-Displacement behaviours.

Tension zone

Shear zone

M

PV

Compression zone

Shear zone

• Reassemble a model of the joint with springs.

Component method with axial force

Axial compression acts together with moment due to restraint to thermal expansion.

K1

K2

Kc

Component method with axial force

Axial compression acts together with moment due to restraint to thermal expansion.

FcKc

F2

F1K1

K2

Ft

M

K

Component method with axial force

Axial compression acts together with moment due to restraint to thermal expansion.

FcKc

F2

F1K1

K2

Ft

F

Component-Based Connection Element (Block)

Compression springs (column web)

One set of tension springs per bolt row (T-stubs, bolts)

i j

• Beam-end and centre line of column assumed to remain plane

• Tension and compression forces have different lines of action

• Only depends on the geometry and the material of the connection

Shear spring (bolts)Zero length

Tension zone Compression zone

Massing’s hypothesis – unloading curve is double the loading curve

Unloading at Constant Temperature

Fo

rce

Fo

rce

-1000-800-600-400-200

0200400600800

-4 -3 -2 -1 0 1 2 3 4 5 6Displacement [mm]

Fo

rce [

kN

]

Load transfer between tension and compression zones

Displacement Displacement

Possible component assembly for reverse channel joint

u

w

fu

w

f

21

Possible component assembly for reverse channel joint

21

u

w

fu

w

f

1

Possible component assembly for reverse channel joint

1

u

w

fu

w

f

F

S

Implementation of joint element in software

I

J

K

L

Robustness

Integrated model should be able to predict connection failure

WP4: Subframe fire tests

Subframe fire tests

• University of Manchester• University of Manchester• University of Coimbra

Coimbra tests

Fire tests on sub-frame

7 full-scale tests on composite frame assemblies including 3 ambient, 1 ISO834 and 3parametric fire curves. Only CFT columns, with steel beams.

Partner Column BeamSteelgrade

Joint typeMRd*(kNm)FCTUC

Partial ** strength

Fire curve

CHS RC 200x100x10 50.4 0.23 20ºC

20ºC, ISO834,

• CHS – circular hollow section 244.5x8 (CFT column)• SHS – square hollow section 250x250x8 (CFT column)• RC – reverse channel joint

** CIDECT Report and EC3-1.8 (ambient temperature) **IPE 300: MRd = 223kN

FC

TU

C

IPE 300 S355

SHS RC 200x75x10 50.4 0.2320ºC, ISO834,

Natural fire

SHS RC 200x75x12 75.5 0.3420ºC,

Natural fire

SHS RC 200x75x16 81.9 0.38 Natural fire

Coimbra subframe tests

Test nº Temperature Columnsection

Jointtype

Reason

1 Ambient CHS RC C1 Reference test at 20ºC

2 Ambient SHS RC S1 Reference test at 20ºC

3 Ambient SHS RC S2 Reference test at 20ºC

4 ISO 834 fire curve SHS RC S1 Joint behaviour under standard fire4 ISO 834 fire curve (+cooling)

SHS RC S1 Joint behaviour under standard firecurve – EC1

5 Natural fire + cooling SHS RC S1 Joint behaviour under natural fire

6 Natural fire + cooling SHS RC S2 Joint behaviour under natural fire

7 Natural fire + cooling SHS RC S3 Joint behaviour under natural fire

WP4: Objectives of subframe testing

• To provide experimental data on interaction between the composite joint and the surrounding structural elements under different fire exposure conditions, including the cooling phase.

• To aid understanding of the joint component behaviour during bending, compression due to restrained thermal expansion of the beam, local yielding and buckling, and catenary action.

Coimbra subframe test details

Coimbra reverse channel connection details

Reverse channel C1

Reverse channel S1

ABAQUS simulations steel-to-steel

ISO834 standard fire exposure up to 60 min (elastic model)

ABAQUS simulations steel-to-CFT

ISO834 standard fire exposure up to 23min (plastic model)

Success at 30 June 2012 if ...

• WP1: Joint thermal behaviour and modelling

• WP2: Component behaviour

• WP3: Component-based joint modelling

• WP4: Fire tests on sub-frames• WP4: Fire tests on sub-frames

• WP5: Integrated FE modelling

• WP6: Demonstration fire tests

• WP7: Development of joint design guides

Thank you Thank you