Nikos Gerolymos

Pushover and Seismic Response of Foundations on Stiff Clay: Analysis with P-Delta Effects

Finite-element analyses are performed for the response to lateral monotonic, slow-cyclic, and seismic loading of rigid footings carrying tall slender structures and supported on stiff clay. The response involves mainly footing rotation under the action of overturning moments from the horizontal external force on—or the developing inertia at—the mass of the structure, as well as from the aggravating contribution of its weight (P-delta effect). Emphasis is given to the conditions for collapse of the soil-foundation-structure system. Two interconnected mechanisms of nonlinearity are considered: detachment from the soil with subsequent uplifting of the foundation (geometric nonlinearity) and formation of bearing-capacity failure surfaces (material inelasticity). The relation between monotonic behavior (static “pushover”), slow-cyclic behavior, and seismic response is explored parametrically. We show that with “light” structures uplifting is the dominant mechanism that may lead to collapse by dynamic instability (overturning), whereas “very heavy” structures mobilize soil failure mechanisms, leading to accumulation of settlement, residual rotation, and ultimately collapse.

On the seismic response of under-designed caisson foundations

The seismic behaviour of caisson foundations supporting typical bridge piers is analysed with 3D finite elements, with due consideration to soil and interface nonlinearities. Single-degree-of freedom oscillators of varying mass and height, simulating heavily and lightly loaded bridge piers, founded on similar caissons are studied. Four different combinations of the static (

The Collapse of the Hanshin Expressway (Fukae) Bridge, Kobe 1995: Soil-Foundation-Structure Interaction, Reconstruction, Seismic Isolation

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CLASS A PREDICTION FOR SEISMIC CENTRIFUGE MODELING OF MULTI-BLOCK QUAY-WALL: UNDRAINED (PLAXIS) VERSUS COUPLED (FLAC) EFFECTIVE STRESS ANALYSIS

FSV) and seismic (

SEISMIC SOIL-PILE INTERACTION — INFLUENCE OF SOIL INELASTICITY

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Development of Winkler model for static and dynamic response of caisson foundations with soil and interface nonlinearities

FSE) factors of safety are examined: (1) a lightly loaded (