Seismic evaluation of an existing bridge pilegroup on liquefiable soil (Canton Bern, Switzerland)

The vast majority of existing bridges were constructed in the 60’s and 70’s with obsolete seismic codes, calling for evaluation of seismic safety according to modern seismic design provisions. In a recent consulting project, we evaluated the pile group foundation of a major bridge in Canton Bern according to Swiss code provisions (SIA 269/8). Our study quantified the liquefaction potential and the post-liquefaction bearing capacity of the existing pile group. Conventional simplified methods were proven to be over-conservative. By employing fully coupled dynamic analysis, in combination with 3D modelling of the pilegroup on conservatively-assumed liquefied soil, it was possible to verify the seismic safety of the bridge, avoiding over-conservative and unjustified foundation retrofit, that would be extremely challenging and costly.

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👉 https://geotechnics.ethz.ch/consulting.html