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4.3.34.44.54.64.7Soil Material Properties Assumed in Model of FieldInstrumented Culverts. . . . . . . . . . . . . . . . . . . . . . . . . . . . .Interface Constraint Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Creep and Shrinkage Strain Prediction in the Concrete Material Model . . .4.5.1 Available Creep Prediction Models. . . . . . . . . . . . . . . . . . . . .4.5.2 Factors Affecting Creep in the Culvert not Considered in theAvailable Creep Prediction Methods. . . . . . . . . . . . . . . . . . . . .4.5.3 Prediction of Creep in the CANDE Model of the BEBO Culvert. . .4.5.4 Prediction of Shrinkage in the CANDE Model of the BEBO Culvert.Structural Response to Creep, Shrinkage, and Temperature Strains . . . . . .4.6.1 Internal Stress Redistribution. . . . . . . . . . . . . . . . . . . . . . . . .4.6.2 Internal Force Redistribution. . . . . . . . . . . . . . . . . . . . . . . . .4.6.3 Method Used to Calculate Structural Response Including theEffects of Creep, Shrinkage, and Temperature Strains in theModified CANDE Code. . . . . . . . . . . . . . . . . . . . . . . . . . . .4.6.4 Structural Analyses by Other Researchers Which Consider theEffect Creep and Shrinkage Strains. . . . . . . . . . . . . . . . . . . . .Validation of the Modified CANDE Code . . . . . . . . . . . . . . . . . . . . . .79909498. .104. . . 118. . . 122. . . 123CHAPTER 5 - COMPARISON OF MEASURED SOIL-STRUCTURE RESPONSEPARAMETERS WITH VALUES CALCULATED WITH THE MODIFIED VERSIONOFCANDE5.1Comparison of Measured Values in the BEBO Arch Culvert and CalculatedValues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.1.1 Comparison of Measured and Calculated Soil Pressures on the BEBOCulvert. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.1.2 Comparison of Measured and Calculated Midspan Culvert Deflections. .5.1.3 Comparison of Measured and Calculated Strain at the Crown of theBEBO Culvert. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.1.4 Comparison of Measured and Calculated Strain near the Springline of theBEBO Culvert. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 .1.5 Comparison of Measured and Calculated Strain in the Floor Slab of theBEBO Culvert. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.1.6 Summary of the Comparison Between Measured and Calculated SoilStructure Interaction Parameters in the BEBO Culvert. . . . . . . . . . . .5.1.7 Calculated Stresses in Soil Surrounding the BEBO Culvert. . . . . . . . .CHAPTER 6 - SUMMARY AND CONCLUSIONS . . . . . . . . . . . .6.1Summary of Field Measurements . . . . . . . . . . . . . .6.2Summary of Finite Element Analysis of the Culvert . .6.3Summary of Finite Element Analysis of the CulvertCapacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .viii107108112113117. . . . . . . . . . . . . . .Design and Ultimate. . . . .131143148150151151152153. 159. 159. 160. 162

6.46.56.6Conclusions Related to the Field Study . . . . . . . . . . . . . . . . . . . . . . . . . . 163Conclusions Related to the Finite Element Analysis of the Culvert Monitored inthe Field Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164Conclusions Related to Analysis of the Culvert Design and Ultimate Capacity . . 165REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167ix

LIST OF FIGURESPageFigure 1.1Figure 1.2Figure 1.3Figure 1.4Figure 1.5Figure 2.1(a)Figure 2.1(b)Figure 2.2Figure 2.3Figure 2.4Figure 2.5Figure 2.6Figure 2.7Figure 3.11Figure 3.12Figure 3.13Figure 3.14Elevation and section of BEBO arch culvert showing locations of soilpressure and strain gages . . . . . . . . . . . . . . . . . . . . . . . . . . . . .BEBO arch details under the high fill . . . . . . . . . . . . . . . . . . . . .Typical section through high fill region showing cement stabilizedbackfill foundation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Vibrating wire strain gage embedded in culvert . . . . . . . . . . . . . . .Earth pressure cell with vibrating wire transducer attached to culvert . .Measured long-term stability of Geokon Model VCE-4200 ConcreteEmbedment Strain Gage (Reference 27). . . . . . . . . . . . . . . . . . . .Measured long-term stability of Geokon Model VCE-4000 strain gagemounted on steel I-beam (Reference 27) . . . . . . . . . . . . . . . . . . . .Corrected and uncorrected readings from a vibrating wire transducersubjected to temperature change (Reference 28) . . . . . . . . . . . . . . .Measured temperature history in a partially shaded concrete bridgemember (Reference 31) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Measured pressure in Geokon pressure cells maintained in a stablelaboratory environment for seven years (Reference 28) . . . . . . . . . . .Difference in height of target points of culvert measured from two surveypoints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Possible effect of differing lines of site from floor points on measuredheight of targets on arches . . . . . . . . . . . . . . . . . . . . . . . . . . . .Corrected difference in height of target points on culvert measured fromtwo survey points. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Effect of hypothesized error in measured angles and baseline on culvertposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Increase in measured soil pressure on culvert with flll depth . . . . . . .Change in measured culvert strain with fill-depth under high fill . . . .Change in measured strain in culvert with fill-depth under low fill . . .Change in measured strain in floor slab with fill-depth under high flll .Typical section through culvert footing in high fill region . . . . . . . . .Arch A deflections during placement of fill . . . . . . . . . . . . . . . . . .Arch B deflections during placement of fill . . . . . . . . . . . . . . . . . .Measured soil pressures on culvert after completion of fill . . . . . . . .Measured strains in culvert under high flll after completion of fill . . .Measured strains in culvert under low fill after completion of fill . . . .Measured strains in floor slab under culvert in high fill after completionof fill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Measured culvert midspan deflection after completion of fill . . . . . . .Arch A deflections after completion of fill . . . . . . . . . . . . . . . . . .Arch B deflections after completion of flll . . . . . . . . . . . . . . . . . .xi. . . . . . . . . .23. . . . . . . . . . . . . . . . .467. . . . .13. . . . .13. . . .14. . . . .17. . . .19. . . . .23. . . . .24. . . . .25.2731353638394142.48495050444647

Figure 3.15Figure 4.1(a)Figure 4.1(b)Figure 4.1(c)Arch C deflections after completion of fill . . . . . . . . . . . . . . . . . . . . . . . .Stress-strain relationship for reinforcing steel . . . . . . . . . . . . . . . . . . . . . . .Stress-strain relationship for concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . .Modulus function for all possible concrete strain histories at a point inthe beam cross section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Elevation and section showing locations of soil pressure and strainFigure 4.2gages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .BEBO arch details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 4.3Stress-strain curves for CD triaxial tests, Canyon Dam silty clay (CLFigure 4.429C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Stress-strain and volume-change curves from CD triaxial tests onFigure 4.5Oroville Dam shell, silty sandy gravel (GP-6) (Hall and Gordon,1963) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Comparison of actual stress-strain curve with hyperbola. . . . . . . . . . . . . . . .Figure 4.6Determination of K and n. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 4.7Figure 4.8Determination of c/ 0 and Ac/ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Hyperbolic stress-strain and volume change curves for Mica Creek DamFigure 4.9core material (SM-SC-lB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Hyperbolic stress-strain and volume change curves for Monterrey No. 0Figure 4.10sand (SP-17B) (Lade, 1971) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Calculated and experimental stress-strain curves for drained triaxial testsFigure 4.11on dense silica sand. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 4.12Calculated and experimental stress-strain curves for drained triaxial testson loose silica sand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Stress-strain and volume change curves for Mica Creek Dam coreFigure 4.13material (SM-SC-lB) (Insley and Hillis, 1965) . . . . . . . . . . . . . . . . . . . .Figure 4.14Determination of Kt, and m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Finite element mesh of instrumented arch culvert under high fill. . . . . . . . . . .Figure 4.15Figure 4.16Finite element mesh of instrumented arch culvert under low fill. . . . . . . . . . .Typical soil density testing report for cement stabilized clay fill. . . . . . . . . . .Figure 4.17Typical soil density testing report for soil fill over culvert . . . . . . . . . . . . . .Figure 4.18Comparison of assumed stress-strain histories considered for silty clayFigure 4.19backfill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Arch culvert footing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 4.20Figure 4.21FEM Model of Arch Culvert Footing . . . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 4.22Creep Coefficient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 4.23(a) ACI Creep Prediction Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 4.23(b) Bazant-Panula Creep Prediction Method . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 4.24Comparison of creep prediction methods for a standard 4000 psi strengthconcrete cylinder loaded at 28 days in 65% relative humidity. . . . . . . . . . .Figure 4.25Comparison of creep predicted with different methods for the BEBOculvert. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 4.26Comparison of ACI 209 and CEB-FIP creep prediction methods todata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xii51. 56585962. 3105

Figure 4.27Superposition principle as applied to concrete creep (from Reference29) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 4.28(a) ACI-209 Shrinkage Prediction Method . . . . . . . . . . . . . . . . . . . . . . . . .Figure 4.28(b) Bazant Panula Shrinkage Prediction Method . . . . . . . . . . . . . . . . . . . . . . .Figure 4.29Comparison of shrinkage strain since reference time (time culvert placedin field) predicted with different methods . . . . . . . . . . . . . . . . . . . . . . . . .Figure 4.30Validation Case 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 4.31Validation Case 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 4.32Validation Case 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 4.33Validation Case 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 5.1Location of soil pressure gages and strain gages in culvert . . . . . . . . . . . . . .Figure 5.2Comparison of calculated and measured soil pressure near crown ofculvert under high fill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 5.3Comparison of calculated and measured soil pressure near springline ofculvert under high fill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Comparison of calculated and measured soil pressure near crown ofFigure 5.4culvert under low fill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 5.5Comparison of calculated and measured crown deflection of culvertunder high fill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 5.6Comparison of calculated and measured crown deflection of culvertunder low fill. . . . . . .Comparison of calculated and measured mid-thickness strain at crown ofFigure 5.7culvert under high fill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 5.8Comparison of calculated and measured mid-thickness strain at crown ofculvert under low fill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Comparison of calculated and measured mid-thickness strain nearFigure 5.9springline of culvert under high fill . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 5.10Comparison of calculated and measured mid-thickness strain nearspringline of culvert under low fill . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Comparison of calculated and measured mid-thickness strain in floor slabFigure 5.11of culvert under high fill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .X-direction stresses in soil in high fill region . . . . . . . . . . . . . . . . . . . . . . .Figure 5.12Y-direction stresses in soil in high fill region . . . . . . . . . . . . . . . . . . . . . . .Figure 5.13Shear stresses in soil in high fill region . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 5.14X-direction stresses in soil in low fill region . . . . . . . . . . . . . . . . . . . . . . .Figure 5.15Y-direction stresses in soil in low fill region . . . . . . . . . . . . . . . . . . . . . . .Figure 5.16Shear stresses in soil in low fill region . . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 138139140141142145146147155156157

SUMMARYObservations of soil pressures and strains in arch components over a 5-year period indicate that:1.The design procedure used for arch segments produced components that have supported imposed soil andenvironmental forces successfully.2.The use of tension tie reinforcement in the slabs under arches beneath high fill was a wise and proper decision,as the tension strains in the floor indicate that the bars developed significant strains.3.Vertical earth pressures exceeded the nominal amount determined for uncompacted density and depth. Measuredvertical pressures imply a soil density in the order of 130 pcf.4.Creep deformations in concrete must be included in analytic procedures in order to obtain displacement responsescorresponding to those measured.5.The redundancies associated with soil-structure interaction tend to produce favorable redistributions of resistanceto soil loads against the arch.6.A sophisticated analytic model of the structural system was shown to produce stress and displacement valuesvery similar to those measured. The analytic model must include specific data regarding soil properties, andcreep response time effects for concrete as well as for soil.XV

CHAPTER!FIELD SETUP AND INSTRUMENTATIONOF REINFORCED CONCRETE ARCH CULVERTIn 1987 and 1988 the Texas Department of Transportation (TxDOT) placed a culvert, consistingof a patented system of precast concrete arches, under Loop 1604 in San Antonio, Texas and authorizedThe University of Texas to monitor the long-term performance of the culvert. A reinforced concretesystem was chosen because cold formed corrugated steel arches had failed to support openings of similarsize (280 ft. 2 flow area) in other recent applications beneath fill depths greater than 15 ft. The patentedsystem of precast arches, called BEBO arch culverts, have an ascetically pleasing shape due to a low-riseprofile and a relatively large span-to-rise ratio. In this case however, these features raised some concernbecause the maximum fill height (24 ft.) over the culvert was much larger than previous fill heightsplaced over BEBO arch culverts. In order to satisfy the concern, two steps were taken. First, astructural engineering firm was employed to design the culvert as a tied arch, using reinforcing steel inthe floor slab to resist lateral spreading of the footings, and to design additional midspan flexural steel.Secondly, The University of Texas at Austin was funded to monitor the long-term performance of theculvert. This report describes the results of the monitoring effort and an analysis of the soil-structuresystem.1.1Culvert and Soil DescriptionIn this chapter and the next two chapters the culvert, the surrounding soil fill, and the monitoringsystem will be described and the measured response of the culvert will be presented and discussed.Figure 1.1 shows a section along the length of the BEBO arch culvert. The arches were precast in eightfoot wide segments and the segments were laid side-by-side to form the 536ft. long culvert. A crosssection through the arch culvert describing the steel reinforcement is shown in Figure 1.2. The floor slaband footings were cast in the field and, after they had cured, the precast arches were transported to theculvert site and placed in the blackouts of the footings. Grout was then placed in the blockout aroundthe base of the arch to cause a tight fit between the arch and footing. As Figure 1.1 shows, there are tworegions of fill depth over the culvert, a high fill region (24 ft. fill) under the mainlanes, and a low fillregion (8 to 10ft.) under the frontage road. In the regions under high fill, 1 in. diameter reinforcingbars extend from the footings and splice with identical bars in the floor slab which extend to the oppositefooting. These reinforcing bars, which are shown in Detail F of Figure 1.2, tie the footihgs together andresist outward horizontal movement of the footings during vertical loading. The 1 in. diameter bars werenot placed in the floor slab in the regions of low fill. In these regions outward footing movement isresisted only by the surrounding soil. The concrete strength of the arch is called out as Class H concrete(minimum compressive strength of 5000 psi). The concrete strength of the footings and floor slab iscalled out as Class C concrete (the standard Texas Highway Department six sack concrete mix with aminimum compressive strength of 3600 psi). All reinforcing steel is A615 steel with a minimum yield1

N'Tj1'- g'[Cl.Iil:asl Hound Matn l1nesolloop 1604"'(1) ·:a.stx1F10ntage RoadtT1ttl0 -[ s·iI 1 .J&mil(JQ[536' Total C Jive11length2 --.1IAroh GagesIt (Aroh B)IA1, A2, A3, A4I1Soil GagesNone ·2(Aroh A)At, A2, A4St,S2:a.3 (Aroh C)A1,A2S2 &m.AGages at Each Cross SectionCross Section3 --.19'·8·"0(j §Q. s· IJl40' 4 l/2.IYetC L SECTION SHOWING ALL GAGE LOCATIONS

f'c 5000 psi minimumGrade 60 Steel9'-8""Tl ·iv !IJ:Itil040'·4 112" SECTION::ri 3'2000 psi Groutft §DETAIL "C" ::ri5Reinforcing SteelSteel Area-4x6 - W16 x W10.5 throughout#9 @ a @ Section B (12' length)@ Section A@ Section B 2" Grout Leveling Pad2.42 inZft (each face)0.42 in21ft (each

The Texas Department ofTransportation (TxDOT) in 1987 placed a BEBO arch culvert system under Loop 1604 in San Antonio. The BEBO arch system is a patented set of precast concrete arch segments set into slotted footings. The San Antonio installation involved a rather large opening of 280 sq. ft. under fill depths in excess of