INNOVATIVE DESIGN OF BRIDGE PIERS ON LIQUEFIABLE SOILS WITH THE USE OF “NATURAL” SEISMIC ISOLATION

Abstract: 

BACKGROUND: Seismic evaluation is most probably of corner stone significance for bridge design in Greece, due to the high seismicity of the Country and the possibility of earthquake-induced liquefaction of the alluvial deposits forming the subsoil at the sites of bridge construction (river crossing, coastal areas, etc.). Due to the above detrimental effects, bridge foundations are presently designed with excess conservatism and at increased cost, most often relying on pile groups combined with extensive ground improvement (e.g. by vibro compaction), as shown in Fig. 1 of the Full Proposal.

AIM: Introduce a theoretically and experimentally documented drastic change in the above design philosophy, aimed to reduce the overall construction cost, without sacrificing performance and safety standards. The key elements of the new methodology are (Fig. 2 of Full Proposal):

  1. Use a raft foundation, without piles.
  2. Create a surface crust of improved ground, with proper thickness and lateral extend so that the seismic response(bearing capacity, settlements, etc.) of the raft is ensured.
  3. Leave intentionally a liquefiable soil layer below the surface crust to act as a "natural" seismic isolation and reduce inertia loads on the superstructure.

EXPECTED RESULTS:

  1. Advanced software for the numerical analysis of seismic soil-structure interaction problems in liquefiable ground.
  2. An integrated, analytical, performance-based-design methodology (PBD) for the seismic design of bridge piers(and other similar heavy structures)on liquefiable soil with the use of raft foundation and "natural" seismic isolation.
  3. Pilot applications of the new methodology to three different bridges types in order to quantify the anticipated benefits from the new design concept and also provide user-oriented calculation examples.
  4. Seismic code provisions for the design of bridge piers (and other similar heavy structures)on liquefiable soil with the new methodology.

Project info

Acronym:
NAT-SEI-ISO
Scientific Coordinator:
Bouckovalas George
Research Team 2 Leader:
Psycharis Ioannis
Research Team 3 Leader:
Kappos Andreas
Research Team 4 Leader:
Mylonakis George

Stats

I.D.:
261
Mis:
380043
Duration (months):
48
Budget:
600 000.00
Diavgeia:
ΑΔΑ: Β4139-ΕΩΗ

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