ductile detailing

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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

• 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.

Simulated seismic damage

Fire loading Aftermath

1 Displacement beyond peak lateral force

900oC -1000oC* Residual lateral capacity test*

2 None 900oC -1000oC for 1 hr Residual lateral capacity test

3 Moderate (30% of the displacement corresponding to peak lateral force)†

900oC -1000oC for 1 hr Residual lateral capacity test

4 Severe (70% of the displacement corresponding to peak lateral force)†

900oC -1000oC for 1 hr Residual lateral capacity test

Summary of the proposed frame tests

*for as long as considered safe (maximum 1 hr) †applied incrementally and cyclically

3000 3000 3000 3000

PO R T IO N O FBU ILD IN G

C O N SID ER ED

P LA N O F B U ILD IN G[4 S TO R E Y (G + 3)]

3000 3000 3000 3000

E LE V A T IO N

C O N SID ER ED

Plan and elevation of the frame sub-assemblage proposed to be tested

3000 3000 3000 3000

C O N SID ER ED

P LA N O F B U ILD IN G[4 S TO R E Y (G + 3)]

3000 3000 3000 3000

E LE V A TIO N30

C O N SID ER ED

Detailing of the frame sub-assemblage

C O L. 300 X 300

L-SECTION OF BEAM (230 X 230)

C O L. 300 X 300

8-2 Legged S tirrups@ 100 m m c /cth roughou t

SECTION 2-2

8-2 Legged S tirrups@ 100 m m c /cth roughou t

18025 25

Detailing of a typical beam

8 bo lts32

150 20 @ 100c/c

bothways

Extended (1200 m m )in ra ft foundation

10-3 LeggedStr. @ 75 m m c/c

40 220 40

8 -2010-2 LeggedStirrups @150 m m c/c

8 -2010-3 LeggedStirrups@ 75 m m c/c

SECTION A-A

SECTION B-B

150 800 150

FOOTING PLAN

REINFORCEMENT OF COLUMN (300 X 300)

8 Bolts o f 32Extended inR aft Foundation

8-20 1100

250 250

Detailing of the column and footing

PLAN SHOW INGBOTTOM REIN. OF SLAB (120 THICK)

PLAN SHOW INGTOP REIN. OF SLAB (120 THICK)

900 900

750750

8 @500 c/c

8 @250 c/c

8 @500 c/c

500 500

8 @250 c/c

8 @ 250 c /cB o thw ays

8 @ 250c/cbothways

SECTION THROUGH SLAB

Detailing of the slab

Brick masonry infill 115 thick

3000 c/c both ways

All Columns- 300x300 mm

Fire compartment

All Beams-230x230

4300 both ways

Column

Framing plan of the frame sub-assemblage

120 thickslab

Test set-up configuration

R aft top R aft top

Ventilationopening

Fire level/Topof beam

Typical colum n,300 x 300

Plinth beam ,230 x 230

Footing,1100 x 1100 x 500

B ricked box con ta ine r filledw ith sand w ith fue l tray on top

(leve l w ith the top o f beam )

Roof slab120 thk

Roof beam230 x 230

Steel fram ingsystem

Sim ulated gravityloading of 2nd and 3rdabove floor

Superim posed live loadon floor 1

Extendedcolum n

Reactionwall

Hydraulicjack

Therm ocouples at fivedifferent elevation levelsin three plan locations offire com partm ent

Brick masonry infill wall in perimeter

Nominal location of thermo-couples and strain gauges

INSTRUMENTATION

Plinth beam230 x 230

Steel rebars

Typical colum n300 x 300

Roof beam230 x 230

6 10 11 155 6

5046 5551 6056

Legend :

: Therm ocouple = 180 : Strain gauge = 72

Nominal location of L.V.D.T.’s

Typical colum n300 x 300

Roof beam230 x 230

Legend :

Total LVDT = 13(PLAN VIEW )

NOMINAL LOCATION OF LVDT

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

Finite element model of the frame sub-assemblage showing hinging in columns

Col. bars=8-12ø

Beam bars=2-12ø+3-16øat top and bottom

Col. bars=8-20ø

Beam bars=3-16øat top and bottom

Plastification atjoint

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

Front elevation of the fire compartment for the mock tests

Thermocouple tree

Fuel tray

Post flash-over phase of the compartment fire

Time (Minutes)

0 5 10 15 20 25

TC at 20 cm TC at 90 cm TC at 160 cm TC at 230 cm

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

Target displacement

Earthquake loading simulation

Proposed (quasi-static) loading history for the frame sub-assemblage

OpenSees analysis of cyclic loading (plotted for 1 column)

Maximum base shear plot from OpenSees analyses

Another Aim of the Project: Stress-Strain Models for Pre-Damaged Materials

•Stressed Tests• Unstressed Tests• Residual Tests

Stress – strain relationships for concrete at elevated temperature

Structural Modelling Round-robinExercise

• 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

• 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

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