Olmati and Giuliani

PROGRESSIVE COLLAPSE SUSCEPTIBILITY OF A LONG SPAN SUSPENSION BRIDGE

Progressive Collapse and Structural Robustness: An International PerspectiveClay J. Naito, Ph.D., P.E., Associate Professor and Associate ChairKonstantinos Gkoumas, Ph.D., P.E., Associate Researcher

Pierluigi Olmati 1

P.E., Ph.D. StudentEmail: pierluigi.olmati@uniroma1.it

Luisa Giuliani 2

Ph.D., Assistant ProfessorEmail: lugi@byg.dtu.dk

1 Sapienza University of Rome2 Technical University of Denmark (DTU)

Olmati P, Giuliani LSapienza University of Rome & DTU

pierluigi.olmati@uniroma1.itwww.francobontempi.org

2 Presentation outline

Introduction on the progressive collapse

The Messina Strait Bridge

Damage based approach and numerical simulations

4 Conclusions

Progressive Collapse case history

Ronan Point – May 16, 1968Progressive Collapse triggered by precast concrete bearing wall failure (gas deflagration).

Ali Khobar – June 25, 1996Progressive Collapse was stopped (ANFO detonation, 9 ton TNTeq).

Oklahoma City – May 19, 1995Progressive Collapse triggered by concrete column failure(ANFO detonation, 1.8 ton TNTeq).

Introduction

Progressive Collapse case history

Deutsche Bank – September 11, 2001Progressive Collapse was stopped(Debris impact).

Introduction

Ronan Point – May 16, 1968

General view of Ronan Point prior to demolition/photo 1987/photographer

M Glendinning

Features:- apartments building;- built between 1966 and 1968;- 64 m tall with 22 story;- walls, floors, and staircases were made of precast

concrete;- each floor was supported directly by the walls in

the lower stories, (bearing walls system).

References: NISTIR 7396: Best practices for reducing the potential for progressive collapse in buildings. Washington DC: National Institute of Standards and Technology (NIST), 2007.

Introduction

Cause Damage Pr. Collapse

Features:- apartments building, built between ‘66 and ’68;- 64 m tall with 22 story;- walls, floors, and staircases were made of precast

concrete;- each floor was supported directly by the walls in

the lower stories, (bearing walls system).The event:- May 16, 1968 a gas explosion blew out an outer

panel of the 18th floor; - the loss of the bearing wall causes the progressive

collapse of the upper floors;- the impact of the upper floors’ debris caused the

progressive collapse of the lower floors.

Introduction

Ronan Point – May 16, 1968

Ali Khobar – June 25, 1996

References: NISTIR 7396: Best practices for reducing the potential for progressive collapse in buildings. Washington DC: National Institute of Standards and Technology (NIST), 2007.

Features:- apartments building;- precast concrete wall and floor components

were the structural bearing system;- ductile detailing and effective ties between the

precast components.

Introduction

Features:- apartments building;- precast concrete wall and floor components

were the structural bearing system;- ductile detailing and effective ties between the

precast components.

The event:- June 25, 1996 9 ton of

TNTeq detonated in front of the building;

- the exterior wall was entirely destroyed;

- collapse did not progress beyond areas of first damage.

Introduction

Ali Khobar – June 25, 1996

Progressive Collapse

Definitions:1- "Progressive collapse is defined as the spread of an initial local failure from element to element resulting, eventually, in the collapse of an entire structure or a disproportionate large part of it." (ASCE 7-05 2005)2- "A progressive collapse is a situation where local failure of a primary structural component leads to the collapse of adjoining members which, in turn, leads to additional collapse. Hence, the total collapse is disproportionate to the original cause." (GSA 2003)3- "Progressive collapse. A chain reaction failure of building members to an extent disproportionate to the original localized damage." (UFC 4-010-01 2003)

References: (ASCE 7-05 2005): "Minimum design loads for buildings and other structures." American Society of Civil Engineers (ASCE).(GSA 2003): "Progressive collapse analysis and design guidelines for new federal office buildings and major modernization projects." General Services Administration (GSA).(UFC 4-010-01 2003): "DoD minimum antiterrorism standards for buildings." Department of Defense (DoD).

Introduction

Disproportionate Collapse ???

Introduction

Disproportionate Collapse ???

Introduction

Conclusions

Messina Bridge

Proposed Messina Strait BridgeLength of main span: 10827 feetHeight of tower: 1255 feet

Golden Gate BridgeLength of main span: 4200 feetHeight of tower: 746 feet

Messina Bridge

Conclusions

Damage based approach, numerical simulations

εy ε 1 ε 2 ε 3

χy χ 1 χ 2 χ 3

(a) (b)M1 σ1

M2 σ2

Flexural My

[MN m] M1

[MN m] M2

[MN m] χy [1/m] χ1 [1/m] χ2 [1/m] χ3 [1/m]

Railways girders

60 63 6.3 0.0015 0.0085 0.01 0.015

Highway girders

130 136.5 13.65 0.001 0.0045 0.005 0.01

Transverse 80 84 8.4 0.00155 0.0095 0.011 0.0155 Axial σy [MPa] σ1 [MPa] σ2 [MPa] εy [-] ε1 [-] ε2 [-] ε3 [-]

Hangers 1620 1782 162 0.0077 0.01925 0.024 0.03

East side

DS1DS2

DS3DS4

DS5DS6

1650 m960 m

not to scale

Airbus A380-800

West side

East side

DS1DS2

DS3DS4

DS5DS6

1650 m960 m

not to scale

Airbus A380-800

West side

1650 m960 m

not to scale

East hanger West hanger

Mid-pointWest extremity point

East extremity point

Damage zone

East side

West side

Moments on the high way deck – DS 1

Mid-point

West extremity point

Yield moment

Mid-point

Yield moment

Mid-point

West extremity point Yield moment

Mid-point

West extremity point Yield moment

Mid-point

Yield moment

Average axial force on the East and West hangers

Relative displacement at the Mid-point

Conclusions

On the numerical simulations:

1- The progression of the damage from the hangers to the bridge deck occurs for at least 8 destroyed hangers.

2 - The complete failure of the deck occurs for at least 10-12 destroyed hangers.

3 - The progression of the damage to an adjoin hanger occurs for 12 destroyed hangers.

Conclusions

On the performance evaluation of this long span suspension bridge:

1- When the damage could be considered disproportionate?

- When the deck fails?- When the damage progresses to an adjoin

hanger?(And when the initial damage could be considered to be local?)

2- Research on the progressive collapse should lead on a quantitative evaluation of the progressive collapse susceptibility.

Conclusions

Progressive Collapse and Structural Robustness: An International PerspectiveClay J. Naito, Ph.D., P.E., Associate Professor and Associate ChairKonstantinos Gkoumas, Ph.D., P.E., Associate Researcher

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