Nondestructive Evaluation for Structural Repair and Rehabilitation - PowerPoint PPT Presentation

ASD 004 Nondestructive Evaluation for Structural Repair and Rehabilitation Jacob Bice, Ph.D., P.E. Issue date: September 21, 2009 Revised: July 10, 2010 MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

What is Structural Diagnostics? MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Traditional Design Process Design Conceptualize Schematic Design Construct Detailed Design Coordination MOORE LEARNING PROGRAM | DMT 102 | JANUARY 2008

The Diagnostic Process Assess Hypothesize Test / Analyze Design Construct MOORE LEARNING PROGRAM | DMT 102 | JANUARY 2008

Firm Profile MOORE LEARNING PROGRAM | DMT 102 | JANUARY 2008

Introduction to NDE MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Agenda  Overview of NDE  Physical phenomena  NDE techniques  Case studies MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

How Do We Characterize Structures? MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

What is Nondestructive Evaluation? Methods for assessing the condition of a structure without causing any structurally significant damage. MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Destructive vs. Nondestructive NDE Approach (better) Original Approach (bad) MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

When is Nondestructive Evaluation Used?  Quality control of new construction  Condition assessment of structures – Rehab – Due diligence – Change of use  Quality control of repairs  Identify as-built construction MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

What are Types of NDE for Concrete Structural Evaluation? Visual Electromagnetic ?? Stress Nuclear Wave Magnetic Electrical MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

What are Common Types of NDE Methods?  Short pulse radar  Stress wave – Impact-echo – Impulse response – Ultrasonic pulse velocity – Ultrasonic Echo  Electric & Magnetic – Half-cell potential  Nuclear – Radiography MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Short Pulse Radar (SPR)  Commonly known as GPR  Reflected electromagnetic waves  Applications – As-built conditions – Rebar location – Voids beneath slabs – CMU grouting – Honeycombing  Limitations – Wet soils – Cannot detect small discontinuities MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

SPR Schematic MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

SPR: Common Limitations PT Slab 4x4 WWR MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Cover Meter Schematic Current Indicator Coil A.C. Source • Presence of bar causes electrical flow • Generates a secondary current • Reinforcement inferred by monitoring current MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Stress Wave Methods  Induce a stress wave (impact)  Measure response MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Impact-Echo  Measure properties of reflected P-wave  Applications – Concrete thickness – Crack depths – Delaminations – Unconsolidated concrete  Limitations – Near surface discontinuities – Edge effects MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Impact-Echo Schematic Crack / Delamination Honeycombing Thickness Receiver Calibrated Weight MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Cambridge Street Approach Slab Cracking  Constructed in 2008  Cracking in 2009 MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

 12” thick reinforced concrete slab  Two layers of reinforcement – #5 bars @ 12” OC – Top and bottom  Are there voids beneath the slab causing settlement? MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Approach Slab GPR CONTROL JOINT LANE OUTSIDE LANDE INSIDE Scan A Scan A REINFORCEMENT LAYER DEPTH: ~6”; SPACING: ~6” MEDIAN LANDE INSIDE BOTTOM OF SLAB SCAN A LANE OUTSIDE DEPTH: ~12” SCAN B PAVEMENT SLAB APPROACH SLAB Scan B Scan B CONTROL JOINT REINFORCEMENT LAYER REINFORCEMENT LAYER AVG. DEPTH: ~8”; SPACING: ~12” AVG. DEPTH: ~8”; SPACING: ~12” MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Impact-Echo Surface Crack Depths 0.04 0.02 81.5 137 0 -0.02 mV Voltage, m -0.04 Vo -0.06 -0.08 -0.1 -0.12 0 50 100 150 200 250 Time, m Tim microseconds MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Validation! MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

FDA Building 71  Under Construction – 2012  Two reinforced concrete structures  Connected by steel framed breezeway –Supported on steel brackets MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

FDA Building 71  Welding  Torch Cutting  Has the concrete behind the embed plate experienced heat damage? MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

FDA Building 71  Impact Echo testing 8” TEST LOCATION 24” SECTION VIEW OF TYPICAL TEST LOCATION MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

TEST 4 TEST 4 TEST 3 TEST 3 TEST 2 TEST 2 TEST 1 TEST 1 TYPICAL TEST LOCATIONS MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

FDA Building 71: Testing Results 1.6 Level 5, Test 1 (No embed PL) 1.4 Level 5, Test 2 (Embed PL,Welded) Level 5, Test 3 (Embed PL, Torch Cut) 1.2 Level 5, Test 4 (No embed PL 1 litude Amplit 0.8 0.6 0.4 0.2 0 0 10 20 30 40 50 60 70 Fr Freque uency, k kHz Thickness Frequency = 3.4 kHz TYPICAL FREQUENCY DOMAIN RESPONSE MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Impact of Testing  Cost to perform testing: $4,500/day + expenses  Total cost of testing: ~$17,000  Approximate cost of repairs: –Chip out and replace concrete: $25,000 per beam x 6 beams $150,000 MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Case Study: Bobby Dodd Stadium MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Case Study: Bobby Dodd Stadium • $75 Million Expansion project • Design Build Project • Tight Schedule • High Profile MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Case Study: Bobby Dodd Stadium • Testing • SPR • Impact Echo MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Findings of Field and NDT Study  SPR of the columns –Concrete cover varied between 2” – 6” –Tie spacing was large at the embedment plate –Headed studs located outside rebar cage  Impact Echo determined cracks were deep and hence needed to be repaired. MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Ultrasonic Pulse Velocity (UPV)  Wave speed through concrete  Applications – Delaminations – Unconsolidated Concrete – Concrete material properties  Limitations – Access to both sides (preferred) – Qualitative MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

UPV Schematic 80 70 410 400 390 Normal Concrete 60 380 370 360 350 340 50 330 320 310 Crack / Delamination 300 290 40 280 270 260 250 Data Acquisition 240 30 230 220 Unconsolidated 210 200 20 Concrete 10 5 10 15 20 MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Parking Garage Fire  Reinforced concrete pan-joist deck  Ford F-150 @ 2 AM  Visible spalls and delaminations  Pink concrete  What is the extent of area which requires repair? MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Parking Garage Fire  Options –Visual –Cores –NDE (!!) MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Parking Garage Fire 26'-10" 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

SAMMC Shear Wall  36-inch thick shear wall  Voids observed after form removal  Visible cold joints  Are there other locations with voids that are not visible? MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

SAMMC Shear Wall 10 5 0 0 5 10 15 20 25 30 35 40 45 50 55 • Black areas denote locations with visible 2000 2200 2400 2600 2800 3000 3200 3400 3600 3800 4000 4200 4400 4600 4800 5000 5200 5400 voids 2000 5600 • Arrows indicate recommended locations for coring MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102

Impulse Response  Low-strain impact  Mobility plot  Applications – Stress transfer – Delaminations – Deep foundation integrity  Limitations – Cannot determine depth of flaws – Qualitative – Verify with coring MOORE LEARNING PROGRAM | Introduction to NDE Techniques| DMT 102