Case Study: Stability Analysis for an Existing Bridge Experiencing Riverbank Erosion-Paper

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The Judge Jodie Stavinoha Bridge over the Brazos River in Southeast Texas has experienced substantial riverbank erosion as the channel migrated north. Three exceptionally severe storms accelerated the process, removing more than 40 feet of soil in some locations and shifting the river’s estimated position about 270 feet from its original location. At Bent 8 and Abutment 9, erosion has exposed drilled shafts, changing parts of the foundations into taller, less-supported columns and increasing exposure to wind and water forces. Further scour remains possible despite a riverbank erosion wall installed in 2017.<br /><br />The study assessed current and potential future conditions using existing geotechnical and bridge data. Analyses considered service, strength, and extreme-event limit states and included dead and live loads, wind, water currents, debris, and earth pressures. Software tools evaluated foundation capacity, column strength, lateral soil support, and structural deflections.<br /><br />Results indicated that the columns and bent caps at Bent 8 and Abutment 9 remain structurally adequate under the current conditions and the analyzed critical scour scenarios. At Bent 8, predicted lateral deflections increased as scour deepened, reaching 3.1 inches longitudinally and 0.8 inches transversely at the critical scour elevation; the shaft tips remained effectively fixed in the analyses. Future performance will depend on continued erosion and changing foundation support. Interactions between Abutment 9 and the nearby erosion wall were not fully evaluated and may require detailed three-dimensional soil–structure analysis.<br /><br />The case study emphasizes that erosion can fundamentally alter a bridge’s structural behavior by reducing foundation embedment, increasing unsupported lengths and loads, and raising deformation or instability risks. Evaluations should therefore combine geotechnical and structural analysis across relevant limit states, and verify that bearings, joints, and utility connections can accommodate anticipated movement.

Keywords

Judge Jodie Stavinoha Bridge

Brazos River

riverbank erosion

scour

bridge foundations

drilled shafts

abutment

Bent 8

geotechnical analysis

structural adequacy