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PRESENTED BY

DEVESHA Y

Dept. of Civil Engg

Seminar on

OUT LINE

Introduction

History

Investigation

Procedure

Qualification of forensic civil engineer

Photo Gallery

Case study

References

FORENSIC CIVIL ENGINEERING

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Forensic civil engineering can be

considered to be “The investigation

of materials, products, structures or

components that fail or do not

operate or function as intended,

causing personal injury or damage

to property’’.

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Bridge failures such as the Tay rail

bridge disaster of 1879 and the Dee

bridge disaster of 1847. Edmond

Locard (1877–1966) was a pioneer in

forensic science who formulated the

basic principle of forensic civil.

"Every contact leaves a trace". This

became known as Locard's "exchange

principle".EDMOND LOCARD

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INVESTIGATION PROCEDURE

”Define” the failure.

Collect evidence.

Analyze the evidence.

The possible events that root causes for the failure.

Validate the hypothesis through structural analysis.

Arrive at a conclusion regarding the cause(s)

Prepare the final report.

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FLOW CHART OF F.C.E INVESTIGATION

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QUALIFICATION OF A F.C.E

Technically competent

Detective

Articulate with good communication skills

Skilful in court

Ethical

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METHODS OF F.C.E

EMPIRICAL METHODS

It contains testing of materials in laboratory

THEORITICAL METHODS

RCA----- Root Case Analysis

ECFC---- Event & Casual Factors Charting

MORT--- Management Oversight & Risk Tree

SSAI----- System Safety Accident Investigation

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NDT METHODS1. Rebound Hammer test

2. Ultrasonic Pulse Velocity test

3. Cover meter test

4. Half-cell Potential Measurement test

5. Impact echo / pulse echo test

6. Ground Penetrating Radar test

SDT METHODS1. Concrete core test

2. Capo test

3. Windsor probe test

4. Load test

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TOOLS (PHOTO GALLERY)

REBOUND HAMMER TEST U P V MACHINE

SCANNING OF REBARS MEASUREMENT OF CORROSION

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MEASUREMENT OF DEFLECTION BY

DEFLECTO METER MEASUREMENT OF DEFLECTION BY

LVDT

LOAD TEST ON PSC DECK OF RAILWAY

BRIDGE EXTRACTION OF SMALLER CORE

SAMPLE FROM MEMBER

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CASE STUDY

THE TACOMA NARROW BRIDGE

1940 2007

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THE TACOMA NARROW BRIDGE Name : TACOMA NARROW BRIDGE

Location: Tacoma, Pierce County, Washington, USA

Start of construction: November 23, 1938

Opened for traffic: July 1, 1940

Traffic per day : 2480 Vehicles/Day

Failure of bridge: November 7, 1940

THE TACOMA NARROW BRIDGE

The famous slender suspension bridge

The third-longest bridge in the world

Total Structure Length 5,939 feet

Suspension Bridge Section 5,000 feet

Center Span 2,800 feet

Width (center-to-center): 39 feet

Withstood winds up to (192kmph)

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FAILURE OF TACOMA BRIDGE

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On November 7, 1940,

The bridge oscillated violently in a 42mph wind and was

literally turn apart and collapsed into Puget Sound.

INVESTIGATION REPORT ON TACOMA BRIDGE

It may best explained by Diane Vaughn,

while commenting on the Challenger Space Shuttle

explosion, described as “normalisation of deviance”

“The gradual acceptance of sequential minor

errors and failures accumulating and

culminating in a major catastrophe”

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FAILURE DUE TO SELF INDUCED OSCILLATION

COLLAPSE OF THE BRIDGE

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Slender suspension bridge in the world.

The designers also “forgot” the slender suspension bridge.

The solid plate girders supporting the bridge deck acted

barriers to wind flow below the deck, while the wind flowed

smoothly above, causing an aero dynamic uplift.

Soon the bridge started oscillating and grew in until finally the

deck structure ruptured and the bridge collapsed.

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RESULTS ON TACOMA BRIDGE

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SUMMARY Forensic Civil Engineering is the application of engineering sciences

to the investigation of failures or other performance problems.

A wide and multi-disciplinary field, requiring civil engineering

expertise and knowledge of legal procedures.

Forensic civil engineering deals with the investigation and

reconstruction of failures in infrastructures.

Engineers & managers need to have a aerial view of the process,

techniques, outcome reporting and legal aspects of forensic civil

engineering investigation

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1. Task Committee on Guidelines for Failure Investigation, "Guidelines for

Failure Investigation", ASCE, 1989.

2. Christoph Kohl, Doreen Streicher, (2006) “Results of reconstructed and

fused NDT-data measured in the laboratory and on-site at bridges”, Cement

& Concrete Composites, 2006, pp.402-413. .

3. Krause M, Barmann R, Friedlinghaus R, Kretzschamar F, Kroggel O,

Langenberg K, Maierhofer Ch, Muller W, Neisecke J, Schickert M, Schmitz

V, Wiggenhauser H., and Wollbold F. (1997), Comparison of pulse echo

methods for testing concrete’ NDT& E International 4 (special issue), 1997,

pp. 195–204.

4. Maierhofer C. (2003) “Nondestructive Evaluation of Concrete Infrastructure

with Ground Penetrating Radar”, Journal of Materials in Civil Engineering,

ASCE, May-June 2003, PP. 287-297.

5. Sansalone, M., and Carino, N. J. (1986) “Impact-Echo: A method for flaw

detection in concrete using transient stress waves”, NBSIR 86-3452,

National Bureau of Standards, Sept., 1986, 222 p.

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