Lightweight technology is an important development trend of ships. Lightweight hull structure design may lead to novel designs that break through existing standards, including new structures or new materials. Based on an overview of the existing safety assessment system for ship structures, it focuses on the safety assessment process and methods for the lightweight structural design, including alternative design process, novelty evaluation indicators and approaches, and methods for determining structural safety assessment criteria based on limit states. The proposed novelty evaluation and safety assessment methods for the lightweight structural design are then applied for practical analysis of the typical cases of the lightweight structural design for oil tankers, bulk carriers, and container ships from literatures published at home. The proposed novelty evaluation and safety assessment methods for lightweight structural design can provide approaches and methods for the structural safety assessment of the corresponding new or alternative designs.

The full-scale measurement has become an important approach to acquire the ice loads due to the lack of the actual ice condition and the corresponding prediction methods for the ice loads acting on the hull. Abundant research achievements have been recently obtained in the full scale measurement with the building of more polar ships and their navigation in ice area. A systematic review is presented about the researches on the full-scale measurement of ice loads worldwide since 2015, including the measured data and methods of full-scale measurement, the methods of converting the full-scale measurement data to ice loads, the factors affecting ice loads and the spatial distribution characteristics, the probability models of ice loads and the prediction methods for the extreme design values. Finally, the main research conclusions of the full scale measurement of ice loads are summarized to provide important reference for the research of ice loads. It is also pointed out that more data accumulation and theoretical discussions are still needed for the application of the extreme ice load prediction methods in the design of full-scale ships.