Pile Foundations of Trieste's New Logistic Platform-Paper

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The new logistics platform at Trieste Port is a pile-supported dock covering more than 70,000 m². Its continuous, post-tensioned reinforced-concrete slab has a trapezoidal plan and is supported by 856 large-diameter marine piles arranged on a 10 m grid. The piles are 1.27 m in diameter and range from 22 to 45 m in length, depending on the depth of the flysch bedrock.<br /><br />A key design feature is the use of double-curvature friction-pendulum isolators between the pile heads and the deck. Because pile lengths—and therefore stiffnesses—vary considerably, direct rigid connections could cause high forces in shorter piles and large displacements in longer ones. The isolators help balance the system: they slide on stiffer piles while more flexible piles can deform themselves. Together, each pile and its isolator act as a nonlinear element, limiting the horizontal force transferred to the pile to about 570 kN.<br /><br />Linear and nonlinear analyses, including seven dynamic simulations using compatible earthquake records, informed the design. Predicted average seismic displacements were about 11 cm, while displacement-based design indicated an approximate upper-bound displacement of 25 cm. The isolation system reduced seismic loads enough to permit a reduction in the planned pile diameter from 1.8 m to 1.27 m.<br /><br />Construction uses prefabricated beam and slab elements, followed by in-situ concrete casting and post-tensioning to accelerate delivery. Piles are installed from pontoons using steel casing, drilling, reinforcement cages and concrete placement. Static and dynamic load tests, along with integrity testing on at least half the piles, are used to verify performance.

Keywords

Trieste Port

logistics platform

pile-supported dock

post-tensioned concrete slab

marine piles

friction-pendulum isolators

seismic isolation

earthquake analysis

nonlinear dynamic simulation

prefabricated construction