ABUTMENT DISTRESS INVESTIGATION - BMIP

October 15-17, 2018

ABUTMENT DISTRESS INVESTIGATION - BMIP

October 15-17, 2018

Frank Estrada III, P.E. – TxDOTGregory Kochersperger, P.E. - HDR

October 15-17, 2018

October 15-17, 2018

Table of contents

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4-8

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11-17

18-34

1-3

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Introduction/Safety

History/Background

Possible Causes of Distress

BMIP Project Scope of Work

Condition Assessment

Evaluation

Recommendations for Detailing Changes

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2

3

4

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6

7

36Moving Forward – What’s Next?8

October 15-17, 2018

History/Background

Abutment Distress to Backwalls– Backwall to Wingwall Connection– Statewide Phenomenon

Cause Investigated– Repair Difficult

Consultant - HDR– Forensic Investigation– Assessment of Bridges for BMIP – 29 bridges evaluated in the Fort Worth District– Years Built: 1976-2002– Skew Angle: 0 through 42 degrees– Foundation Types: Drilled Shafts & H-Piles– Founded Into: Sandstone, Limestone, Shale, Clay

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October 15-17, 2018

Abutment Corners w/o Forward Wingwalls

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October 15-17, 2018

Abutment Corners with Forward Wingwalls

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October 15-17, 2018

Abutment Corners w/o a Cheeckwall – Previously Repaired

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October 15-17, 2018

Abutment Corners with Backwalls – Isolated from Retaining Walls

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October 15-17, 2018

Possible Causes of Distress

INITIAL ASSUMPTIONS: Concentrated forces Backfill Earth pressure loads Environmental Loads applied through the Approach Slab Localized loading

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October 15-17, 2018

BMIP Project Scope of Work

Condition Assessment– Perform condition assessment of the abutments of all 29 bridges– Perform geotechnical borings at 8 representative locations

Evaluation– Evaluate trends in distress of 29 bridges– Survey other districts and State DOT’s– Identify possible sources of distress– Investigate possible sources with FEA models– Identify most likely root cause and make recommendations for repair– Provide recommendations for possible modification to statewide

standards

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October 15-17, 2018

Condition Assessments

Inspected 29 bridges across FTW over 5 days in January ‘18

Documentation of every abutment corner– Took photos– Mapped crack patterns– Measured large cracks– Measured rotations– Noted evidence of

settlement

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October 15-17, 2018

Condition Assessments - Summary

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NBI # (Name)Type and Observed Damage by Corner

Begin (Left) Begin (Right) End (Left) End (Right)

02-127-0-0259-05-069US 67 over CR 801 (B-07)

Cat 1 - Severe Cat 1 - Severe Cat 1 - Severe Cat 1 - Moderate

02-127-0-0259-05-072US 67 over CR 805

Cat 1 - Severe Cat 1 - Severe Cat 1 - Severe Cat 1 - Severe

02-127-0-0259-05-074BUS 67 over US 67

Cat 1 - Severe Cat 1 -Moderate Cat 1 - None Cat 1 - None

02-127-0-0422-03-032US 67 SB over W. Buffalo Creek (B-06)

Cat 1 - Severe Cat 1 - Severe Cat 1 - Moderate Cat 1 - Severe

02-220-0-0008-13-337Campus Dr over IH 20

Cat 1 - Early Cracking


Cat 1 - Minor Cat 1 - Moderate

02-220-0-0008-13-354IH 20 EB over UPRR

Cat 1 - Severe Cat 1 - Early Cracking

Cat 1 - Minor Cat 1 - Early Cracking

02-220-0-0008-13-421IH 35W Conn A over IH 35W & Sycamore Creek

Cat 1 - None Cat 1 - Early Cracking


Cat 1 - Minor

02-220-0-0008-13-422IH 20 Conn B over IH 35W, IH 20 & Sycamore Trib



Cat 4 - Minor

02-220-0-0008-13-423IH 35W Conn C over IH 35W & Sycamore Creek (B-05)



Cat 3 – Early Cracking


02-220-0-0008-13-424IH 20 Conn D over IH 35W, IH 20 & Sycamore Trib



Cat 4 - None Cat 1 - Minor

02-220-0-0008-14-208IH 820 WB over BNSF (FWD RR) (B-01)

Cat 2 - Moderate Cat 2 - Minor Cat 2 - Moderate Cat 2 - Early Cracking

02-220-0-0008-14-260IH 820 WB over Navajo Trail





02-220-0-0008-14-261IH 820 EB over Navajo Trail

Cat 2 - Minor Cat 2 - Minor Cat 2 - Minor Cat 2 - Minor

02-220-0-0008-15-227IH 820 NB over Clifford St (B-02)

Cat 2 - Moderate Cat 2 - Early Cracking

Cat 2 - Severe Cat 2 - Severe

02-220-0-0008-15-228IH 820 SB over Clifford St

Cat 2 - Severe Cat 2 - Minor Cat 2 - Severe Cat 2 - Moderate

NBI # (Name)Type and Observed Damage by Corner

Begin (Left) Begin (Right) End (Left) End (Right)

02-220-0-0008-15-254IH 820 SB over Silver Creek Rd

Cat 2 - Moderate Cat 2 - Moderate Cat 2 -Moderate

Cat 2 - Minor

02-220-0-0008-15-255IH 820 NBL over Silver Creek Rd

Cat 2 - Minor Cat 2 - Moderate Cat 2 -Moderate

Cat 2 -Moderate

02-220-0-0008-15-296IH 820 NBL over Chapin Rd


Cat 2 - Minor Cat 2 - Severe Cat 2 - Minor

02-220-0-0008-16-305IH 20 WB Collector over UPRR & Walnut Creek

Cat 2 - Moderate Cat 2 - Moderate Cat 2 -Moderate

Cat 2 -Moderate

02-220-0-0008-16-322IH 20 EBL over IH 820 SB & SBFR (B-04)

Cat 2 – None Cat 3 - Minor Cat 2 - Early Cracking

Cat 3 - Minor

02-220-0-0008-16-327IH 20 Connection L over IH 20 & IH 820

Cat 2 - Moderate Cat 2 - Minor Cat 2 - Early Cracking

Cat 2 - Minor

02-220-0-0008-16-328IH 20 Connection M over Ramp T & IH 820 SBFR

Cat 1 - Minor Cat 2 - Moderate Cat 2 -Moderate

Cat 2 - Minor

02-220-0-0353-03-183SH 114 EB over Kimball Ave

Cat 1 - Severe Cat 1 – Minor Cat 1 - Minor Cat 1 - Severe

02-220-0-0353-03-184SH 114 WB over Kimball Ave (B-08)

Cat 1 - Severe Cat 1 - Severe Cat 1 - Severe Cat - Severe

02-220-0-1068-02-107Ballpark Way over IH 30

Cat 1 - Severe Cat 4 - Minor Cat 1 - Minor Cat 4 - Minor

02-220-0-1068-02-330Bridgewood Dr over IH 30 Conn (B-03)

Cat 1 - Moderate Cat 1 - Moderate Cat 1 - Minor Cat 1 - Severe

02-220-0-1068-02-332Bridgewood Dr over IH 30 Conn J

Cat 1 - None Cat 1 - None Cat 1 - Severe Cat 1 - Severe

02-220-0-1068-02-348IH 820 NB Coll over IH 30 Conns H &C




02-220-0-1068-02-375Conn B over IH 820 & IH 30



Cat 4 - None --

Cat 1 – Normal WingwallsCat 2 – Forward WingwallsCat 3 – Previous RepairsCat 4 – No Wingwalls

October 15-17, 2018

Condition Assessment – Other Observations

Pavement Relief Joints – SH114 at Kimball Ave

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January 17th, 2018Temperature below 50 degrees

May 10th, 2018115 degree pavement temperature

October 15-17, 2018


Riprap Movement

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Significant riprap settlement Voids under riprap

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Lateral Ground Movements

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October 15-17, 2018

Condition Assessment – Geotechnical Work

Borings were taken behind the abutment backwall at 8 locations

Voids were not observed underneath the approach slab during the geotechnical investigation– Voids were observable through the backwall

at some locations during the condition assessments

– Results are inconclusive for whether voids are present

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October 15-17, 2018

Condition Assessment – Geotechnical Work

Results: Any embankment settlement has already occurred (Newest Bridge was built

in 2002) Underlying soils do not appear to be highly susceptible to settlement The source of the observed riprap and approach slab settlement is likely the

embankment settlement, or erosion

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October 15-17, 2018

Evaluation – Survey of TxDOT Districts and Other States

TxDOT District survey– Received responses from 9 of 25 Districts

State Survey– Initial screening of states’ details and standard practices revealed 7

states with details similar to TxDOT (Stub Abutments, Non-integral)– Sent to 7 States, 6 surveys returned

Also performed a review of literature associated with backwall damage, embankment movements, and pavement growth

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October 15-17, 2018

Evaluation – Survey Results - TxDOT

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DistrictSimilar

Distress Observed

% of Bridges Other Comments

Beaumont Yes 20% Mostly CRCP approaches, suspect pavement growth. Also experiencing significant settlement (>2”) at end of approach slab

Brownwood No 0% ½” to 1” settlementBryan Yes 5% No CRCPChildress Yes 10% Observed with both asphalt pavement and

CRCP. 1” to 2” of settlementDallas Yes 60%** Observed with asphalt, jointed concrete, and

CRCP approaches. 1” to 2” of settlement at end approach slab

Paris Yes <1% No significant issuesPharr Yes 5% Asphalt approach pavement, distress has been

associated with local erosion of backfillTyler Yes 7% Asphalt approach pavementWichita Falls Yes 2% Both asphalt pavement and CRCP approach

October 15-17, 2018

Evaluation – Survey Results – Other States

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StateSimilar

Distress Observed

% of Bridge Approach Slab Detail Other Comments

Arkansas Yes Not provided 36ft approach slab supported on bracket, free to rotate

Suspect pavement growth

Georgia Yes <1% 30ft approach slab supported on bracket, free to rotate

Jointed pavement or asphalt pavement, wingwall is set outside of bridge rail

Iowa Yes <10% 20ft approach slab supported on bracket, free to rotate

Most damage to backwalls is attributed to de-icing fluid.

Louisiana Yes 10% 20ft – 40ft depending on approach fill condition

Jointed concrete pavement

Missouri Yes <10% 20ft approach slab, pinned at top of backwall

Jointed approach pavement.

Oklahoma Yes 10% 30ft approach slab, pinned at top of backwall

Rail supported on approach slab, inside of wingwall. Asphalt or jointed concrete pavement approaches.

October 15-17, 2018

Evaluation – Survey Results - Themes

Approach settlement is common nationwide Pavement growth is suspected, although there is anecdotal evidence of

distress without CRCP Other states allow approach slab rotation at the top of the backwall

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Florida Detail with Dowels at Approach Slab Connection

October 15-17, 2018

Evaluation – 3D Finite-Element Analysis

Used LUSAS for modelling Linear 8 node solid elements, Frame

elements and Multi-linear Springs Captures soil-structure interaction with

p-y springs

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Backwall Plate Study– Evaluate the effect

of uniform load or moment applied at top of idealized backwall

– 3 sided support

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Probable Load Cases for Analysis– Primary Drilled Shaft Differential Settlement– Wingwall Drilled Shaft Settlement/Downdrag– Excessive Lateral Earth pressures– Pavement Growth– Ground Movement– Live Load Applied to an Unsupported Approach Slab

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Live Load Applied to an Unsupported Approach Slab

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October 15-17, 2018

Evaluation – 3D Finite-Element Analysis - Results

Primary Drilled Shaft Differential Settlement

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Wingwall Foundation Settlement/Downdrag

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Excessive Lateral Earth pressures – At Rest Pressures

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Excessive Lateral Earth pressures – Passive Pressures (Expansive Soil)

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Pavement Growth – ¾” Movement applied to back of approach slab

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Ground Movement

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Live Load Applied to an Unsupported Approach Slab

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October 15-17, 2018

Evaluation – Conclusion from Analysis

Analysis indicates two probable root-causes– Pavement growth– Settlement combined with live load on unsupported approach slab

Some pavement relief joints are open Settlement of the approach slabs was consistent

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The most probable cause of the distress seen in the 29 FTW bridges appears to be loss of support of the approach slab due to settlement of embankment material or erosion of backfill material followed by the application of live load on the approach slab.

October 15-17, 2018

Recommendations for Detailing Changes

Two recommendations for potential revisions to current details:– Reduce Stiffness (Florida DOT detail):

• Single row of dowels to connect the approach slab to backwall• Set wingwalls outside of edge of deck and install rail on the approach slab

– Increase Stiffness (Houston District detail):• Support approach slab on the wingwalls• Utilize a secondary approach slab to provide addition movement

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Both options limit applied moments at top of backwall and prevent water infiltration of backfill material.

October 15-17, 2018

Moving Forward – What’s Next?

Bridge Division (BRG)– Apply Recommendations– Action Plan Coming– Contact BRG Division if a District would like to try some of the

recommendations What repairs do we continue to use moving forward?

– Continue to use the TxDOT Concrete Repair Manual

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October 15-17, 2018 37

THANK YOU

QUESTIONS

ABUTMENT DISTRESS INVESTIGATION - BMIP

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