Seismic Vulnerability Assessment of Jacket Type Offshore Platforms

Abstract

Most of oil and gas offshore platforms are located in the seismic regains. Therefore, Seismic vulnerability evaluation of the offshore platforms is one of the essential vital issues in the structural systems. In this article, jacket type offshore platforms are examined by incorporating the pushover analyses and nonlinear time history analyses, in such a way that, first some push over analyses are performed to detect the more critical members of the jacket platform in consonance with the range of their plastic deformations. Subsequently, nonlinear time history analyses are performed, concentrating on the critical members, to examine the vulnerability of the jacket platform under intensive earthquake loads. Pursuant to the numerical results, the combination of the push over analyses and nonlinear time history analyses proposes a reliable and swift seismic assessment procedure to evaluate the seismic vulnerability of the offshore platforms. Moreover, seismic vulnerability of the offshore structures is dependent on the critical member locations and their load bearing situations in the offshore structures.