Finite Element Study on the Effect of Barge Impact on Bridges with Different Pile Group Configurations-Paper

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The study used three-dimensional finite-element models to examine barge impacts on the M19 pier of Louisiana’s I-10 Twin Span Bridge. It compared vertical, battered, and mixed pile-group configurations under impacts from a 1,873-ton barge traveling at 2, 4, and 6 knots. The models included the barge, bridge structure, pile groups, and site soils.<br /><br />The vertical pile group had the lowest lateral stiffness and experienced substantially greater impact forces and pile-cap displacements—up to 8.4 inches, compared with about 2.0–2.5 inches for the battered and mixed groups. Vertical piles also sustained significant damage and retained residual displacement. The battered and mixed groups had similar, higher stiffness and showed no damage in the modeled impacts; their stiffness also led to greater bow deformation and energy absorption.<br /><br />The foundation carried about 65–75% of the total lateral force in the vertical configuration, with the pier columns carrying the remainder. In the battered and mixed configurations, piles carried approximately 82% and columns 18%. Force distribution among rows was relatively even in the battered group; the vertical group’s leading row carried a modestly larger share, while the mixed group showed greater variation.<br /><br />Pile bending moments were higher in the vertical group, largely because of its greater pile-cap movement. Across all configurations, edge-column piles had higher bending-moment ratios, and the leading row had the largest row-level ratio (69–72%). Overall, the findings indicate that battered and mixed pile arrangements provide greater resistance to barge impact than vertical piles in the modeled conditions.

Keywords

barge impact

finite-element models

M19 pier

I-10 Twin Span Bridge

pile-group configurations

vertical piles

battered piles

mixed piles

lateral stiffness

pile-cap displacement