FORENSIC CIVIL ENGINEERING

BYDEVESHA Y

OVERVIEW ON PRESENTATION1. Introduction2. History3. Investigation4. Procedure5. Qualification of forensic civil engineering..6. Photo Gallery7. Case study8. ****THE TACOMA NARROW BRIDGE9. Reference

FORENSIC CIVIL ENGINEERING

FORENSIC CIVIL ENGINEERINGForensic 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.

HISTORY OF F.C.Ebridge 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 science: "Every contact leaves a trace". This became known as Locard's "exchange principle".

EDMOND LOCARD

INVESTIGATION PROCEDURE1. Describe or ”define” the failure 2. Collect evidence3. Analyze the evidence – which itself would involve

several activities including material testing 4. Hypothesize the possible sequence of events that led to,

and the root causes for, the failure 5. Validate the hypothesis through structural analysis,

model testing, research, literature review etc. 6. Arrive at a conclusion regarding the cause(s) that

resulted in the failure 7. Prepare the final report fully describing the process

adopted, with supporting documentation,

FLOW CHART OF F.C.E INVESTIGATION

QUALIFICATION OF A F.C.E1. Technically competent

2. Detective

3. Articulate with good communication skills

4. Skilful in court

5. Ethical

METHODS OF F.C.E EMPIRICAL METHODS :• It contains testing of materials in laboratory as well as physically

• Liquid penetrate test , X-ray test so on..

THEORITICAL METHODS :

1. RCA----- Root Case Analysis

2. ECFC---- Event & Casual Factors Charting

3. MORT--- Management Oversight & Risk Tree

4. SSAI----- System Safety Accident Investigation

NDT methods :

1. Rebound Hammer test 2. Ultrasonic Pulse Velocity test 3. Cove meter test 4. Half-cell Potential Measurement test 5. Impact echo / pulse echo test 6. Ground Penetrating Radar test

SDT methods :

7. Concrete core test 8. Capo test 9. Windsor probe test 10.Load test for flexural member

TOOLS (PHOTO GALLERY)

Rebound Hammer test on RC member U P V MACHINE

Scanning of rebars in RC member

Measurement of corrosion in rebar

Measurement of deflection by Deflect meter during load test Measurement of deflection by LVDT during

load test

Load test on PSC deck of Railway bridge

Extraction of smaller core sample from member

CASE STUDIES IN F.C.E :THE TACOMA NARROW BRIDGE

IN 1940 IN 2007

THE TACOMA NARROW BRIDGE

•The famous suspension bridge was supposed to have been the third-longest bridge in the world when it was completed (1940), with a total length of 5,939 feet (1,811m), comprising a 2,800 ft. (854m) centre span and two 1,100 ft. (335m) end spans. It was supposed to have withstood winds up to 120 miles per hour (192kmph)

INTRODUCTION

FAILURE OF TACOMA BRIDGE• On November 7, 1940 the bridge oscillated violently in a 42 mph (67 kemps) wind and was literally torn apart and collapsed into Puget Sound. • Remarkably no one was killed, but for a lone dog which had to be abandoned in a stranded car on the bridge.• The whole failure was captured on 16mm movie film by a local photographer and has some dramatic footage

INVESTIGATION REPORT ON TACOMA BRIDGE

It may best explained by what Diane Vaughn, while commenting on the Challenger Space Shuttle explosion, described as “normalisation of deviance” i.e.. “the gradual acceptance of sequential minor errors and failures accumulating and culminating in a major catastrophe”The series of successful bridges in the years had imbued designers with such supreme confidence their knowledge and abilities, that they brushed aside contrary evidence.

The Tacoma Narrows Bridge slender suspension in the bridge in the world. The designers also “forgot” the suspension bridge ,The solid plate girders supporting the bridge deck acted as barriers to wind flow below the deck, while the wind flowed smoothly above, causing an aerodynamic uplift. Soon the bridge started oscillating and grew in until finally the deck structure ruptured and the bridge collapsed. It has always been popularly, but incorrectly, been explained as a classic case of “harmonic resonance” but the more accurate explanation is now held to be a case of “ aero-elastic” (self-induced oscillation)

FAILURE DUE TO SELF INDUCED OSCILLATION

COLLAPSE OF THE BRIDGE

The wreckage of the destroyed first Tacoma Narrows Bridge still remains in the waters of Puget Sound, The Second Tacoma River Bridge was subsequently built in 1950, designed with much greater understanding. From the lessons learned from the Tacoma disaster, the Bronx-Whitestone Bridge, which also used a plate-girder supported deck, was later extensively retrofitted to withstand the design wind forces.

EPILOGUE:

COLLAPSE OF TACOMA.mp4

VIDEO MEDIA

REFERENCE1. BULLETIN OF ACCE (I) APR-JUNE 2013 2. http://www.youtube.com/watch?v=j-zczJXSxnw3. http://en.wikipedia.org4. http:// www.fadooengineers.com