  A new digital twin (DT) framework with optimal sensor placement (OSP) is
proposed to accurately calculate the modal responses and identify the damage
ratios of the offshore jacket platforms. The proposed damage identification
framework consists of two models (namely one OSP model and one damage
identification model). The OSP model adopts the multi-objective Lichtenberg
algorithm (MOLA) to perform the sensor number/location optimization to make a
good balance between the sensor cost and the modal calculation accuracy. In the
damage identification model, the Markov Chain Monte Carlo (MCMC)-Bayesian
method is developed to calculate the structural damage ratios based on the
modal information obtained from the sensory measurements, where the
uncertainties of the structural parameters are quantified. The proposed method
is validated using an offshore jacket platform, and the analysis results
demonstrate efficient identification of the structural damage location and
severity.
