Earthquake Engineering Services for Offshore Platforms, Azerbaijan
GR8 GEO provided earthquake engineering services for the development of two offshore platforms in the Caspian Sea, offshore Azerbaijan. GR8 GEO performed the following tasks for the project:
• Site characterization, development of idealized stratigraphy and soil properties for use in dynamic analyses
• Probabilistic Seismic Hazard Assessment (PSHA) for the development of “competent-soil” horizon vertical and horizontal ground motions. The study included development of seismotectonic model for the project, performance of PSHA and development of stiff soil spectra in accordance with ISO 19901-2 (2017)
• Development of spectrum compatible time histories using spectral matching.
• Total stress site response analyses to develop estimates of cyclic stress ratios for use in liquefaction triggering evaluations.
• Free-field linear elastic site response analyses to propagate the vertical motions (P waves) from a “competent” soil horizon to the seafloor.
• Liquefaction triggering evaluations to evaluate the potential of the sands present at the sites to develop significant pore pressures under the design events
• 2D effective stress kinematic soil-structure interaction analyses to develop depth varying free-field ground motions and acceleration response spectra applicable at the pile head for use in structural evaluations of the platforms
• Development of lower bound and upper-bound dynamic springs for use in earthquake loading evaluations of the platform structure