1-INTRODUCTION: MONITORING OF THE STRUCTURES IS ESSENTIAL FOR ENSURING THEIR SAFETY IN SERVICE. THE PROCESS ASSUMES GREATER SIGNIFICANCE IN THE CASE OF OFFSHORE PLATFORMS, SINCE MAJOR PARTS OF THE STRUCTURE ARE UNDER WATER WHICH ARE HIGHLY VULNERABLE TO DAMAGE DUE TO THE HARSH MARINE ENVIRONMENT. THIS WORK IS AN EXPERIMENTAL INVESTIGATION ON A LABORATORY MODEL OF A JACKET PLATFORM FOR DEVELOPING A SYSTEM IDENTIFICATION METHODS USING TIME SERIES SIGNAL FOR LONG-TERM STRUCTURAL HEALTH MONITORING PURPOSES IN THIS KIND OF STRUCTURES. THIS APPROACH IS BASED ON STOCHASTIC AUTO REGRESSIVE MOVING AVERAGE WITH EXOGENOUS INPUT (ARMAX) AND FUZZY LOGIC SYSTEM (FLS) WITH PROBABILISTIC ANALYSIS.