October 9, 2013

An Important note from the Principal Investigator Abolhassan ASTANEH-ASL on the document that follows:

The following PowerPoint was presented to combined students enrolled in CE92 and CE92 in the Department of Civil and Env.

Engineering at University of California, Berkeley in 2002.

Abolhassan ASTANEH-ASL, Ph.D., P.E.

Professor and Principal Investigator for the NSF Funded UC Berkeley WTC Project (Duration: 10-2001 to 9-2002)

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Special Joint Lecture of CE92/CE24

World Trade Center and Engineering

Aspects of 9/11

Abolhassan Astaneh-Asl, Professor (www.ce.berkeley.edu/~astaneh)

University of California, Berkeley

WTC

9/11

Investigation

Future?

Credit:Wtcphotos.com

This document is part of the “World Trade Center Post-Disaster Reconnaissance and Perishable Structural

Engineering Data Collection”, a research project funded by the U.S. National Science Foundation at the Univ. of

California Berkeley with Prof. Abolhassan ASTANEH-ASL as Principal Investigator

(http://www.ce.berkeley.edu/~astaneh) as the Principal Investigator. Duration of the project was from 10/2001 to

9/2002. Further Information and project archives are at http://lib.berkeley.edu/ENGI/WTC. © 2001 Abolhassan

ASTANEH-ASL.

"This work is licensed under a Creative Commons Attribution-NonCommercial -No Derivatives License."

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The lecture is dedicated to the memories

of all victims of 9/11 attacks and to the

firefighters, police officers and other first

responders who so heroically sacrificed

their lives to save others. A. Astaneh-Asl

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Outline

1. Tall Buildings

2. Protection against terrorist attacks

3. World Trade Center

4. Lessons learned and future work

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Q. How and Where did Skyscrapers Start?

A. In Chicago, 1880’s

Source of Graphics: Tall Building Structures, Analysis and Design, by Bryan Stafford Smith and Alex Coull, John Wiley & Sons

Major Developments:

1. Steel

2. Electric Elevator

Nu

mb

er

of

Sto

ries

10

0

80

60

40

20

0 1850 1890 1870 1930 1910

Otis’s

Elevator

Steel

Rolled

New York

Era

Chicago

School

Wrought

Iron

and Cast

Iron Era

Elec.

Elev.

Year

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World’s 10 Tallest Buildings

WTC 1 2 3 4 5 Petronas Sears Jin Mao Citic Plaza Shun Ming Malaysia Chicago China New York China China

88 stories 110 stories 88 stories 110 stories 80 stories 69 stories

1,483 ft 1,450 ft 1,381 ft 1,360 ft 1,283 ft 1,260 ft

6 7 8 9 10 Empire State Central Plaza Bank of China Emirates Tower 1 The Center New York Hong Kong Hong Kong U.A. E. Hong Kong

102 stories 78 stories 70 stories 55 stories 79 stories

1,250 ft 1,227 ft 1,209 ft 1,165 ft 1,148 ftt 6 of 40

Who Designs and Builds a

Skyscraper?

1. Architects design aesthetic and allocate spaces

2. Structure Engineers design the structure to carry the loads

3. Fire Engineers design fireproofing

4. Geotechnical Engineers design foundations

5. Environmental Engineers design hydraulic and other env. systems

6. Construction Engineers build them

7. Mechanical Engineers design mechanical systems

8. Electrical Engineers design electrical systems

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Height of Skyscrapers

1368ft 1381 1450 1483 1509 1883ft

Planned, not

completed yet 8 of 40

Forces that buildings are

designed for:

Some Buildings

in Recent Years

Wind Blast Seismic Gravity Planes

Only

WTC Designed

for Boeing 707

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World Trade Center Design,

Construction,

and September 11 Events

Credit:Photographer Unknown

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The Architect

Minoru Yamasaki

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The Structural Engineer

Leslie E. Robertson

Credit:Photo by Alan McWeeney/New Yorker

LERA Photo

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Typical Framing System Water Tower Place, Chicago

Credit: 100 World’s Tall Buildings Credit: “Building Structures” by W. Schuller

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The Steel Structure

Credit:PANYNJ

Towers had large column-free areas

209 ft

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Tube System

Credit: PANYNJ

Column Section 15 of 40

Floors

Credit: PANYNJ

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World Trade Center

Construction

Credit:PANYNJPhotographer Unknown

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Construction of WTC Tower

Credit:PANYNJ

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Car bomb caused collapse of 3

parking floors but structure

survived.

The 1993 Attacks

Credit: Engineering News Record 19 of 40

World Trade Center

The 9/11 Attacks

Credit:Photographer Unknown

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3-D Plane Hit Areas and Casualties

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External and Internal Columns as well as

floors were damaged in 3 floors

Plane Impacting the Structure

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Plane Impacting the Structure

External and Internal Columns as well as

floors were damaged in 3 floors

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External and Internal Columns as well as

floors were damaged in 3 floors

Ensuing Fires

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The

damaged

floor

collapsed

dropping

top portion

on the lower

part

collapsing

the entire

structure

Final Collapse Due to Gravity

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Post Collapse Investigation of WTC Steel Structure

(Sept. ’01-Present)

By A. Astaneh-Asl

Research Funded by the

National Science Foundation

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http://lib.berkeley.edu/ENGI/WTC

Copyright © 2001 Abolhassan ASTANEH-ASL

Studies of World Trade Center, Principal Investigator: A. Astaneh-Asl , University of California, Berkeley

Sponsor: National Science Foundation

27 of 40 http://lib.berkeley.edu/ENGI/WTC

Here are some examples of our field findings.

Photo: A. Astaneh-Asl Photo: HNSE

Photo by W. Farrington for A. Astaneh’s NSF Report Photo by A. Astaneh-Asl

Copyright © 2001 Abolhassan ASTANEH-ASL

Copyright © 2001 Abolhassan ASTANEH-ASL

Copyright © 2001 Abolhassan ASTANEH-ASL

Photo by William Farrington for A. Astaneh’s WTC NSF Project. Copyright © 2001 UC Board of Regents

FEMA/ASCE BPAT Work (Oct. ‘01-March ’02)

Hindrances to investigations:

The recycling of steel structure, loss of perishable

data, FEMA/ASCE non-disclosures agreement, ….

and outrage of the victim’s families and firefighters

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Hearings of

the Committee on Science,

U.S. House of Representatives

Chairman Boehlert,

Committee on Science

A. Astaneh-Asl

University of California

A bill was introduced in Congress to establish “National

Construction Safety Team” within Dept. of Commerce (NIST) to

investigate future building collapses as well as the WTC

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Here at UC-Berkeley, we have continued analytical studies

of the WTC with collaboration of researchers and

engineers from LLNL, IIT, and MSC Software Corp.

UC-Berkeley and MSC Software Corporation

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Close ups

Fully loaded plane entering the structure and damaging it..

Studies of World Trade Center, Principal Investigator: A. Astaneh-Asl , University of California, Berkeley

Sponsor: Civil and Mechanical Systems Program, National Science Foundation

University of California Berkeley and MSC Software Corporation

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University of California, Berkeley and MSC Software Corporation

Studies of the World Trade Center

Principal Investigator: A. Astaneh-Asl , Sponsor: National Science Foundation

Fire Heating-

up Damaged

Structure,

Weakening it

and the

Structure

Collapses

under the

Gravity Load.

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Current Status of our Studies

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Future of WTC?

One of the first attempts

Ref: The New York Times

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Developing Protective Systems

At University of California, Berkeley

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The car bomb exploded too close to the building,

knocking out columns and transfer girders. Then due

to progressive collapse, ½ of the building collapse

under gravity load.

The Case of Progressive Collapse of

Murrah Building, Oklahoma City, 1995

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Analysis at LLNL and Actual Full Size

Test at Univ. of California at Berkeley

Vertical Displacement of

20.8 inches

Cables

A.Astaneh-Asl, D. McCallen, E.

Madsen, B. Jones, R. Jong, W. Li,

Y.Zhao,

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http://lib.berkeley.edu/ENGI/WTC

Copyright © 2000 Abolhassan ASTANEH-ASL

Composite Shear Walls Can Be Used

Around Stairwells to Protect Egress

Routes

Research Data on Fire Resistance Can be Useful

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http://lib.berkeley.edu/ENGI/WTC

Copyright © 2000 Abolhassan ASTANEH-ASL

Lessons Learned and Concluding

Remarks

1. Need better fire protection for structures

2. Need better egress routes for the occupants

3. Need new systems to prevent progressive collapse

4. Developers, architects, structural engineers and fire engineering should work together from the start of the project and consider safety of the occupants the highest priority regardless of the cost.

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Wish you still were here, …

Photo by: Andre Souroujon

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….and more than 3000 of our loved ones who so

violently perished on 9/11.