AN ADJACENT BOX BEAM BRIDGE Box Girders Shear Keys Tie Rods - - PDF document

SPR 4009 Box Beam Study 2/14/2019 1

ADJACENT PRESTRESSED, PRECAST BOX BEAM BRIDGES

RYAN WHELCHEL, Purdue University RYAN MOLLEY, KPFF LUIS FELIPE URREGO, Universidad de los Andes ROBERT FROSCH, Purdue University CHRISTOPHER WILLIAMS, Purdue University

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• Box Girders
• Shear Keys
• Tie Rods
• Wearing Surface

AN ADJACENT BOX BEAM BRIDGE

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PROJECT MOTIVATION

• History of poor durability and performance
• Economical and simple to build
• Over 43,000 in US and 4,000 in Indiana

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RESEARCH PLAN

• Acquire decommissioned bridge girders
• Research and acquire NDT equipment
• Conduct non‐destructive evaluation
• Perform structural tests
• Load test an existing bridge to determine load

distribution of a non‐composite deck on a bridge without shear keys

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SPECIMEN ACQUISITION

• Determine those bridges that will be replaced
• Inspect bridges to determine specimen quality
• Contact County, Engineer, or Contractor to

coordinate girder salvage

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COMMON DETERIORATION

• Longitudinal Cracking
• Exposed or Broken Strand

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BOX BEAM SPECIMENS

Wells Co. Bridge 79

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BOX BEAM SPECIMENS

Newton Co. Bridge K5

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BOX BEAM SPECIMENS

Elkhart Co. Bridge 102

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NONDESTRUCTIVE TESTING

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NON‐DESTRUCTIVE EVALUATION (NDE)

Ground Penetrating Radar (GPR) Connectionless Electrical Pulse Response Analysis (CEPRA) Half‐cell potential measurement

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PRELIMINARY NDE RESULTS

Specimen 409‐1‐ES Span: 50’ Depth: 29” Width: 36”

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PRELIMINARY NDE RESULTS

Connectionless Electrical Pulse Response Analysis

Low Moderate High

5.1 10.3 15.4 20.6 25.7 30.9 36.0 5 10 15 20 25 30 35 40 45 50

Transverse Location (in.) Longitudinal Location (ft)

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PRELIMINARY NDE RESULTS

Half‐cell potential measurement

5.1 10.3 15.4 20.6 25.7 30.9 36.0 5 10 15 20 25 30 35 40 45 50

Transverse Location (in.) Longitudinal Location (ft) Low Moderate High

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STRUCTURAL TESTING

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BEAM TEST

Load Points Roller Bearing (TYP) Reaction Block (TYP) String Potentiometers (two at midspan)

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BEAM TEST

Specimen 409‐1‐ES

• Three exposed strands at L/8 from support

Specimen 409‐2‐UD

• No damage

~ 12 in.

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BEAM TEST

10 20 30 40 50 60 5 10 15 20 25

Applied Force (kip) Midspan Deflection (in.)

42 kip - Undamaged Capacity 34 kip - Damaged Capacity 52 kip - Test 47 kip - Theory

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BEAM TEST

10 20 30 40 50 60 5 10 15 20 25

Applied Force (kip) Midspan Deflection (in.)

42 kip - Undamaged Capacity 47 kip - Theory 50 kip - Test

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BEAM TEST

10 20 30 40 50 60 5 10 15 20 25

Applied Force (kip) Midspan Deflection (in.)

52 kip - Test 47 kip - Theory 50 kip - Test

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FIELD TESTING

TIPPECANOE COUNTY BRIDGE 115

• Built: 1957
• Rehabilitated: 1993
• Span: 40 ft
• Beam Depth: 21 in.
• Beam Width: 45 in.
• 7 Beams

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INTRODUCTION

INSTRUMENTATION

10’ 10’ 10’ 10’

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LOADING

Dump Truck

• Weight: ~ 58,000 lb
• 30% to front axle
• 70% to tandem axle
• Wheelbase: 16’ – 4”

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• T E S T 1

T E S T 2 T E S T 3 T E S T 4

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Bridge Deck Modifications

• Milling
• Shear Key Cutting
• Surface Preparation
• Bridge Deck Cast

FIELD TESTING

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10' 10' 10' 10'

East West

‐0.2 ‐0.18 ‐0.16 ‐0.14 ‐0.12 ‐0.1 ‐0.08 ‐0.06 ‐0.04 ‐0.02 1 2 3 4 5 6 7 Midspan Deflection (in.) Beam Number

LT1 ‐ Original Condition LT2 ‐ Asphalt Removed LT3 ‐ Shear Keys Disabled LT4 ‐ Concrete Deck Placed

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10' 10' 10' 10'

East West

‐0.2 ‐0.18 ‐0.16 ‐0.14 ‐0.12 ‐0.1 ‐0.08 ‐0.06 ‐0.04 ‐0.02 1 2 3 4 5 6 7 Midspan Deflection (in.) Beam Number

Original Condition Concrete Deck Placed

35% reduction in deflection

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LOAD DISTRIBUTION

• The proportion of load carried by a given

beam was calculated as follows 𝐸𝐺 ∆ ∑ ∆

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10' 10' 10' 10'

East West

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0% 5% 10% 15% 20% 25% 30% 1 2 3 4 5 6 7 Load Distribution Beam Number LT01 LT04

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10' 10' 10' 10'

East West

0% 5% 10% 15% 20% 25% 30% 1 2 3 4 5 6 7 Load Distribution Beam Number LT01 LT04

1 2 3 4 5 6 7

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LOAD DISTRIBUTION SUMMARY

Load Test Interior Exterior LT01 22% 23% LT04 22% 25%

Design Distribution Factors

Interior Exterior 21% 24% AASHTO LRFD 2017 Load Fraction (truck) 32% AASHTO Standard Specification 2002

Experimental Distribution Factors

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FIELD TEST CONCLUSIONS

• Concrete deck restored load distribution to a

code level

• Durability and stiffness were added to the

system

• Composite action between the deck and the

beams was achieved

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IMPLICATIONS TO BEST PRACTICE

• Recommend all new construction use

concrete decks

• Potential new design of adjacent box

beam bridges without shear keys

Concrete Deck Sealant Standard Box Beam Shape

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PROJECT BENEFITS

• Improved inspection capability for bridge

inspectors

• Increase in bridge load rating accuracy
• Development of next generation box beams

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ACKNOWLEDGMENTS

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THANK YOU

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