Research Categories / Seismic

Earthquake Assessment of Subsea Facilities/GOM

Project to assess the vulnerability, operability, and safety of sub-sea production systems in the GOM during earthquakes of varying probabilistic seismic intensities. The assessment involved participation from industry and regulatory representatives to define current sub-sea systems, technologies, operation, concerns, and the potential mitigation actions during times of events (earthquakes).

Large-Scale Modeling of Pipeline Soil Interaction Under Lateral & Axial Loading

This project evaluated the force-displacement response of buried pipelines under saturated sand and clay conditions under lateral loading. This research was full scale. A review of accepted methods of offshore pipeline/soil interaction analysis, especially pertaining to mudslides and earthquake-related hazards was conducted.

Continued Development of Earthquake Load and Resistance Factor Design

This project will continue development of the earthquake Load and Resistance Factor Design (LRFD) guidelines for offshore structures. The focus is on three topics: 1) concrete Gravity Base Structures, 2) seismic hazard characterizations, and 3) verifying of the proposed ISO guidelines. The unique characteristics of concrete gravity based platforms will be addressed, including seismic loading considerations and soil-structure interaction. The results of selected seismic hazard studies will be reviewed to determine the accuracy of the guidelines for specifying the design spectrum.

Ground Motion Attenuation Equations for Basin Environments

This is a Joint Industry Project (JIP). The purpose was to develop a set of attenuation equations that could be used to confidently estimate the ground motions in offshore basinal environments that are generated by crust earthquakes. Attenuation equations for computing earthquake ground motions are a key input in deterministic and probabilistic seismic hazard analysis.

Probabilistic Seismic Hazard Analysis for Offshore Platforms in the Santa Barbara Channel

A probabilistic seismic hazard analysis (PSHA) will be conducted to assess the levels of vibratory ground motions expected during various time periods. The results will be used to update current seismic hazard maps that have been used in the Santa Barbara Channel area since the 1960's, in the review of seismic design criteria and seismic performance of offshore structures. This is a 2 year, 3 phase project. The first phase of the study will collect data from the USGS, MMS, relevant experts, and oil companies to identify all available seismic design criteria for offshore platforms.

Development of Evaluation Guidelines for Offshore Platform Topsides in Seismic Regions

This is a Joint Industry Project (JIP). The project evaluated guidelines for offshore platform topsides in seismic areas and review technical issues, such as the calculation of deck acceleration and the application of offshore seismic experience to offshore facilities. The project had two phases to develop guidelines then test on actual platforms and refine before implementation. The first phase developed the evaluation methodology, screening evaluation criteria, and methods of documentation.

Methodology for Assessing the Structural Integrity of Existing Platforms Subject to Seismic Loading

The objective was to develop a systematic seismic hazard approach for the requalification of existing platforms. The need for quantified assessment of the safety implications of inspections and repairs has led to incorporating such information into the decision process. No definitive engineering guidelines have been developed for defining a program for platforms located in seismically active areas. The research resulted in development of a practicable methodology for the safety management of fixed platforms in areas subject to earthquakes.

International Workshop on Pile Foundation

The workshop explored the current state-of- the-knowledge concerning the effects of pile driving on adjacent soil properties and determined areas where more research may be required. It is recognized that the properties of soils are sometimes changed by the installation of piles and that time- dependent effects are often part of these changes. The workshop sought to develop avenues of research to lead to the prediction of soil modification by pile driving so that altered properties can be considered in design of pile foundations.

Analytical Simulation of Biased Loaded Tension Piles in Earthquakes

This was a Joint Industry Project (JIP) and is an adjunct to Project No. 128. The study consisted of scaled laboratory tests of model piles loaded in biased tension during simulated earthquakes under two conditions that an earlier study suggested may be critical for the design of such piles. Piles used for foundations such as those for tension-leg platforms and pile-supported hydraulic structures. These conditions, were addressed in two separate tasks, including: