Fire Testing of an Earthquake
Damaged R.C. Frame
Presented by: U.K. Sharma/Pradeep Bhargava
Under UKIERI Project being Jointly Investigated by:
Indian Institute of Technology Roorkee
University of Edinburgh, U.K.
Indian Institute of Science Bangalore
INTRODUCTION
Major earthquakes have been followed by multiple ignitions
• San Francisco, 1906
• Tokyo, 1923
• San Fernando, 1971
• Northridge, 1994
• Hanshin (Kobe), 1995
• Izmit (crude and naptha tanks), 1999
Fire Following Earthquake
Probability of Ignition is high.
• Toppled furniture, electrical malfunctioning and
movement of hot equipment.
Active and passive systems may be damaged by
earthquake.
• Probability of prompt fire service attention is much lower.
• Due to rapid urbanisation, there is an increasing risk of
Fire Following Earthquake (F.F.E.) events.
• FFE events have added a new dimension to disaster
management and call for substantial research effort to
address the relevant challenges .
• The collaborative research project between the
University of Edinburgh, Indian Institute of Technology
Roorkee and the Indian Institute of Science Bangalore
proposes to conduct large-scale tests to investigate the
behaviour of (earthquake-induced) pre-damaged R.C.
frames in fire.
Summary of the proposed frame tests
1
Simulated seismic
damage
Displacement beyond
peak lateral force
Fire loading
Aftermath
900oC -1000oC*
Residual lateral capacity
test*
Residual lateral capacity
test
Residual lateral capacity
test
2
None
900oC -1000oC for 1 hr
3
Moderate (30% of the
displacement
corresponding to peak
lateral force)†
900oC -1000oC for 1 hr
4
Severe (70% of the
displacement
corresponding to peak
lateral force)†
900oC -1000oC for 1 hr
*for as long as considered safe (maximum 1 hr)
†applied incrementally and cyclically
Residual lateral capacity
test
3000
3000
3000
3000
3000
3000
3000
3000
3000
3000
4000
3000
3000
3000
3000
4000
PORTION OF
BUILDING
CONSIDERED
PORTION OF
BUILDING
CONSIDERED
4000
4000
3000
3000
3000
3000
3000
3000
3000
3000
3000
3000
PLAN OF BUILDING
[4 STOREY (G + 3)]
PLAN OF BUILDING
[4 STOREY (G 3000
+ 3)]
3000
3000
3000
4500
3000
CONSIDERED
4500
PORTION OF
BUILDING
PORTION
OF
CONSIDERED
BUILDING
3000
4000
4000
ELEVATION
ELEVATION
Plan and elevation of the frame sub-assemblage proposed to be tested
Detailing of the frame sub-assemblage
3-16
COL. 300 X 300
COL. 300 X 300
230
2
8-2 Legged Stirrups
@ 100 mm c/c
throughout
2
L-SECTION OF BEAM (230 X 230)
25 180
25
120
230
3-16
3-16
SECTION 2-2
Detailing of a typical beam
8-2 Legged Stirrups
@ 100 mm c/c
throughout
40
220
40
8-20
10-2 Legged
Stirrups @
150 mm c/c
300
1500
10-2 Legged
Str. @ 150 mm c/c
500
10-3 Legged
Str. @ 75 mm c/c
SECTION A-A
230
10-2 Legged
Str. @ 150 mm c/c
40
220
40
500
8-20
10-3 Legged
Stirrups
@ 75 mm c/c
300
10-3 Legged
Str. @ 75 mm c/c
SECTION B-B
A
250
3000
A
250
8 Bolts of 32
Extended in
Raft Foundation
B
B
300
8-20
1100
300
10-2 Legged
Str. @ 150 mm c/c
150
800
150
500
1100
10-3 Legged
Str. @ 75 mm c/c
FOOTING PLAN
800
230
10-2 Legged
Str. @ 150 mm c/c
10-3 Legged
Str. @ 75 mm c/c
150
75
150
300
500
8 bolts
32
20 @ 100c/c
bothways
Extended (1200 mm)
in raft foundation
REINFORCEMENT OF COLUMN (300 X 300)
Detailing of the column and footing
8 @ 250c/c
bothways
8 @ 250c/c
bothways
PLAN SHOWING
TOP REIN. OF SLAB (120 THICK)
PLAN SHOWING
BOTTOM REIN. OF SLAB (120 THICK)
900
900
8 @
250 c/c
8 @
500 c/c
8 @
250 c/c
120
500
750
230
8 @
500 c/c
750
8 @ 250 c/c
Bothways
SECTION THROUGH SLAB
Detailing of the slab
500
Brick masonry infill 115 thick
F
Column
Beam
Fire compartment
4300 both ways
3000 c/c both ways
All Columns- 300x300 mm
All Beams-230x230
Framing plan of the frame sub-assemblage
120 thick
slab
Simulated gravity
loading of 2nd and 3rd
above floor
Extended
column
1500
Reaction
wall
Steel framing
system
Superimposed live load
on floor 1
Roof slab
120 thk
Roof beam
230 x 230
Thermocouples at five
different elevation levels
in three plan locations of
fire compartment
Brick masonry infill wall in perimeter
3000
5000
Hydraulic
jack
4300
Typical column,
300 x 300
Ventilation
opening
Plinth beam,
230 x 230
Raft top
Footing,
1100 x 1100 x 500
Bricked box container filled
with sand with fuel tray on top
(level with the top of beam)
Test set-up configuration
500
1300
Fire level/Top
of beam
Raft top
INSTRUMENTATION
Steel rebars
Typical column
300 x 300
1
5
1
16
6
2
3
20
17
10
5
6
11
Roof beam
230 x 230
15
4
31
18
7
8
9
10
35
15
21
3000
4000
16
25
36
40
3300
3000
13
26
14
11
30
12
41
45
Plinth beam
230 x 230
46
50
51
55
56
Legend :
60
Total
: Thermocouple = 180
: Strain gauge = 72
Nominal location of thermo-couples and strain gauges
4000
Typical column
300 x 300
4000
Roof beam
230 x 230
Legend :
LVDT
(PLAN VIEW)
Total LVDT = 13
Nominal
location
L.V.D.T.’s
NOMINAL
LOCATION
OFof
LVDT
4000
230
1
5
10
6
1
2
3
4
4000
120 mm thick slab
21
25
9
5 thermocouples
through thickness
of slab
10
2 strain gauges
16
20
7
11
8
15
5
6
Typical column
300 x 300
230
230
Total thermocouples = 25
Total strain gauges = 10
230
Nominal location of thermocouples and strain gauges in the slab
Analytical modeling of the frame sub-assemblage
•
The sub-assemblage was designed as part of a 4-storey moment
resistant R.C frame located in seismic zone IV of IS 1893 (Part 1):2002.
Ductile detailing was carried out as per IS 13920.
(a)
(b)
Detailing of a typical beam, (a), and a column, (b).
• When calibrated against the Eurocode 8, the design was found to be
sufficiently ductile. However, a plastic analysis of the sub-assemblage
indicated that the first hinge formed in a column instead of a beam
Beam bars=2-12ø+3-16ø
at top and bottom
Col. bars=8-12ø
Finite element model of the frame sub-assemblage showing hinging in columns
Plastification at
joint
Beam bars=3-16ø
at top and bottom
Col. bars=8-20ø
Beam hinging
The modification of detailing in the beams and columns resulted in a more
Desirable pattern of hinging
Analytical load-displacement relationships
(a) SAP frame model
(b) ABAQUS finite element model
Comparison of the predicted load-displacement relationships for the
frame sub-assemblage from SAP and ABAQUS
Mock Fire Tests
Thermocouple tree
Fuel tray
Front elevation of the fire compartment for the mock tests
Post flash-over phase of the compartment fire
1400
1200
Temperature (°C)
1000
800
600
TC at 20 cm
TC at 90 cm
TC at 160 cm
TC at 230 cm
400
200
0
0
5
10
15
20
25
Time (Minutes)
Time-temperature relationships for the fire compartment near the
centre of the back wall and opposite to the opening
Strong floor – reaction wall system
Detailing of rebars in the strong floor, dowels for the footing can also be seen
Freshly cast concrete in the strong floor, dowels for the orthogonal reaction
walls can be seen in the background
Erection of the reinforcement cage for the reaction wall. Pipe sleeves for
anchoring the loading jacks can also be seen
The quasi-static loads shall be applied with a pair of these 500 kN capacity
double acting hydraulic jacks
Earthquake loading simulation
Target displacement
Time
Proposed (quasi-static) loading history for the frame sub-assemblage
OpenSees analysis of cyclic loading (plotted for 1 column)
80000
Base Shear (N)
0
-0.4
-0.2
0.0
0.2
0.4
Displacement
(m)
-80000
dispBeamColumn
forceBeamColumn
beamWithHinges
Maximum base shear plot from OpenSees analyses
300
Base Shear (kN)
250
200
150
100
dispEle_Corotational
forceEle_Corotational
WithHinges_Corotational
50
0
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Displacement (m)
0.8
0.9
1.0
Another Aim of the Project: Stress-Strain Models for
Pre-Damaged Materials
Present
Models
•Stressed Tests
• Unstressed Tests
• Residual Tests
Stress – strain relationships for concrete at elevated temperature
Structural Modelling Round-robin
Exercise
• The challenge:
– To model blind the behaviour of a concrete
structure during fire following earthquake
• Aiming to
– Identify strengths and weaknesses of modelling
capabilities
• If interested contact Martin Gillie:
– m.gillie@ed.ac.uk
– www.see.ed.ac.uk/~s0458490/UKIERI/
Predictions
•
•
•
Horizontal and vertical deflections during
the earthquake loading
Temperature of the rebar during heating and
cooling
Horizontal and vertical deflections during
heating and cooling
Dates
•
•
•
•
Competition announced June 2010
Structural data on website Summer 2010
Date of test Late Summer 2010
Confirmation of required predictions Day
after test
• Submission of predictions 1 March 2011
• Results conference Spring 2011
THANK
YOU