Plataform off shore

CASE OF A
SIMPLE OFFSHORE STRUCTURE

Anchal Jatale

Abstract

This paper discusses about the different types of risks associated with anoffshore structure and how to perform a multi hazard risk analysis in order to make it safe.

Introduction

Multi hazard Risk analysis is concerned withthe performance of structures subjected to multiple random loads, some of which may occur simultaneously. Separate investigations of single processes only might lead to a misjudgment of the generalrisks for these offshore structures. To avoid this trap, risk assessments should not focus on a singular process but on multiple processes. Within this study a general methodology is developed toanalyze risk for multiple processes

To focus and illustrate the presentation of the methodology, we will examine a simple model of an offshore structure subjected to earthquake shakingand sea-storm-generated wind, wave and current loads .Also we will compute the integrated risk in he presence of multiple loads and determine the relative importance of different loads in function ofboth the structural and load characteristics.

An offshore structure during its design life is subjected to intermittent loads due to earthquake and sea storms[2] The intensities of these loads,their occurrence patterns, the load parameters, the dynamic characteristics of the structure, and the structural resistance are all uncertain. In this paper we will see a methodology to do the riskanalysis due to these uncertain stuffs.

In general an offshore oil-platform is exposed to four different combinations of the earthquake and sea storm loads. These loads can act in variouscombinations. Four major combinations on which we will examine risk are as follows [1]:

• Earthquake load alone
• Earthquake load plus ambient load
• Sea-storm load alone
• Earthquake load plus...