RESEARCH SYNTHESIS

LOAD RATING REINFORCED CONCRETE BOX CULVERTS

William D. Lawson, P.E., Ph.D.

Department of Civil and Environmental Engineering Texas Tech University

STGEC 2013 44th Southeast Transportation Geotechnical Engineering Conference Crowne Plaza Hotel: Baton Rouge, LA Wednesday, December 4, 2013

FIRST PROJECT: TXDOT 0-5849 EVALUATING EXISTING CULVERTS FOR LOAD CAPACITY ALLOWING FOR SOIL STRUCTURE INTERACTION 2007-2009

RESEARCH SYNTHESIS LOAD RATING REINFORECED CONCRETE BOXED CULVERTS

Load Rating Culverts Slide 2 STGEC: 4 DEC 2013

The Research Problem

• When rights-of-way crossing existing culverts have to be raised and/or widened, the culverts have to be reanalyzed.

• Current analysis methods (direct stiffness) and AASHTO loading protocols often result in such culverts being judged deficient.

• The direct-stiffness method is too conservative in that it does not account for (beneficial) soil-structure interaction effects.

Load Rating Culverts STGEC: 4 DEC 2013 3

Load Rating Culverts STGEC: 4 DEC 2013 4

Load Rating Culverts STGEC: 4 DEC 2013 5

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Modification

• New Problem: TxDOT’s “current” rating procedure was not clear, repeatable

• Solution: articulate a clear, repeatable procedure in the Culvert Rating Guide

• Quality Assurance: conduct a series of quality checks to demonstrate that the Culvert Rating Guide is clear, repeatable, and valid for TxDOT culverts

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Culvert load rating is about going from here…

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to here…

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I) (1 LA

DA C RF

2

1

Load

Rat

ing

Flo

w C

har

t C

ulv

ert

Ra

tin

g G

uid

e

Load Rating Culverts TxDOT 5-5849-03 10

Load Rating Culverts STGEC: 4 DEC 2013 11

Load Rating Culverts STGEC: 4 DEC 2013 12

so you can check here.

Field Instrumentation and Load Testing

• Live Load and Operating Rating Case Studies – Case 1: Shallowater

• 2’ Fill

• 4’ Fill

– Case 2: Plainview

– Case 3: Tulia

• Dead Load Concerns

• Conclusions

• Recommendations

Load Rating Culverts STGEC: 4 DEC 2013 14

Culvert Selection: Shallowater, Plainview, Tulia

Load Rating Culverts STGEC: 4 DEC 2013 15

Case 1: Shallowater Instrumentation Plan

ETEC ETEM ETIC1 ETIC2 ETIM ETIC3

EWTECITEC ITEM ITIC1 ITIC2 ITIM ITIC3

IBEC IBEM IBIC1 IBIC2 IBIM IBIC3 IBIC4

IWTEC IWTIC1 IWTIC2 IWTIC3 IWTIC4

IWBEC IWBIC1 IWBIC2 IWBIC3 IWBIC4

median drainage

4'-0"

4'-0"

8" 8"

7 12

"

LVDT TES

LVDT BES

LVDT TIS

LVDT BIS

4'-0" 1'-0" 1'-0" 4'-0" 1'-0" 1'-0" 4'-0"

IWEM

MA

TCH

LIN

E

4'-0"

IWIM1 IWIM2 IWIM3 IWIM4

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Lay Out the Gage Line

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First Pass: One Truck Straddles Gage Line

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Third Pass: Two Trucks Straddle Gage Line

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Data Recording

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-10.000

-8.000

-6.000

-4.000

-2.000

0.000

2.000

4.000

6.000

8.000

CULV-5 MAX

CULV-5 MIN

RISA-2D TEXT MAX

RISA-2D TEXT MIN

RISA-2D STRUC MAX

RISA-2D STRUC MIN

RISA-2D LEFE CRG MAX

RISA-2D LEFE CRG MIN

RISA-2D LEFE Bowles MAX

RISA-2D LEFE Bowles MIN

RISA-2D LEFE SPT/TCP MAX

RISA-2D LEFE SPT/TCP MIN

RISA-2D LEFE DCP MAX

RISA-2D LEFE DCP MIN

RISA-2D LEFE PMT MAX

RISA-2D LEFE PMT MIN

RISA-2D LEFE FWD MAX

RISA-2D LEFE FWD MIN

ACTUAL MAX

ACTUAL MIN

Case 1: Shallowater: 2’ Fill Live Load Moment Predicted and Measured

Validation of the TxDOT Culvert Rating Guide

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0.01 0.1 1 10 100 1000

Level 3 DOF=4.0ft

Level 3 DOF=3.5ft

Level 3 DOF=2.0ft

Level 3 DOF=1.5ft

Level 1 DOF=4.0ft

Level 1 DOF=3.5ft

Level 1 DOF=2.0ft

Level 1 DOF=1.5ft

predicted / measured

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SECOND PROJECT: TXDOT 5-5849-01 SOFTWARE DEVELOPMENT TO IMPLEMENT THE TXDOT CULVERT RATING GUIDE 2012-2013

RESEARCH SYNTHESIS LOAD RATING REINFORECED CONCRETE BOXED CULVERTS

Load Rating Culverts Slide 23 STGEC: 4 DEC 2013

CULVLR 1.0.2

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CULVLR Input

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CULVLR Critical Section Details

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CULVLR Capacity Calculations

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CULVLR Demand Modeling

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CULVLR Load Rating Calculations

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THIRD PROJECT: TXDOT 5-5849-03 LOAD RATING TXDOT CULVERT DESIGN STANDARDS 2012-2013

RESEARCH SYNTHESIS LOAD RATING REINFORECED CONCRETE BOXED CULVERTS

Load Rating Culverts Slide 31 STGEC: 4 DEC 2013

Completed Load Rating Work • Digitization of TxDOT’s Design Standards for CULVLR (1855 Designs)

• Level 1/AASHTO Policy Load Ratings of Designs (~60,000 Load Ratings)

– CULV5 (60/30pcf Equivalent Fluid Weights)

– Range of Depths of Fill • Level 3/AASHTO Policy Load Ratings of Designs (~2,500 Load Ratings)

– RISA-3D (High, Medium and Low soil stiffnesses)

– Critical Depth of Fill from Level 1/AASHTO Load Ratings • Level 1/TxDOT Practice Load Ratings of Designs (~60,000 Load Ratings)

– CULV5 (40/20pcf equivalent fluid weights; ignore bottom slab)

– Range of Depths of Fill

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5-5849-03 Load Rating Standard Designs

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Load Posting Chart 5-5849-03 Culvert Rating Guide

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5-5849-03 Volume 1 All Analyses – Level 1/AASHTO

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145, 8% 18, 1%

196, 10%

694, 37%

587, 32%

215, 12%

OR < 3

IR<3, OR>3

IR>3, OR<10

IR<20, 10<OR<20

IR<20, OR>20

IR>20, OR>20

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Load Rating Culverts STGEC: 4 DEC 2013 37

5-5849-03 Volume 2 All Analyses – Level 3/AASHTO

0

215 215 215

0

587 587 587

215

261 155

15

587

574

485

168

694

208

166

302

196

0

8

55

18

0

0

4

145 10

21

96

0 0

0

195

0 0

218 218

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Level 1 AASHTO Level 3 High Level 3 Medium Level 3 Low

Pe

rce

nta

ge o

f To

tal L

oad

Rat

ings

Case D - NG

Case C - NG

OR < 3

IR<3, OR>3

IR>3, OR<10

IR<20, 10<OR<20

IR<20, OR>20

IR>20, OR>20

Case B - OK

Case A - OK

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Culvert Load Rating Lessons Learned 1. Culvert load rating is highly complex.

2. Production load rating tools achieve efficiency in effort at the expense of analytical simplification, the result being excess conservatism (non-uniform).

3. Increased analytical sophistication reduces excess conservatism.

4. TxDOT’s culvert designs are generally good relative to the policy for which they were designed; that is, TxDOT culvert design standards have not been heavily over-designed.

5. Load rating applies to a physical culvert structure where all key parameters are identified.

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cte

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Construction year

Culverts by Construction Year

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Much remains to be done…

TxDOT PMC

• Bernie Carrasco, PE (PD)

• Keith Ramsey, PE

• Farren Basse, PE

• Jon Kilgore, PE

• Roger Lopez, PE

• Mark McClelland, PE

• Mark Steves, PE

• Gregg Freeby, PE

TechMRT

• Timothy Wood, MS

• Chuck Newhouse, PhD, PE

• Priyantha Jayawickrama, PhD

• Stephen Morse, PhD

• Suranga Gunerathne

• Rozbeh Moghaddam

• William Lawson, PE, PhD (RS)

TxDOT Lubbock

• Ron Baker, PE

• Ted Moore, PE

• Benito Sanchez, PE

• Lubbock NW, Plainview, & Tulia Maintenance Sections

TxDOT 0-5849 Project Team

THANK YOU!!!