Recent progress in computer science and stringent requirements of the design of "greener" buildings put forwards the research and applications of simulation-based optimization methods in the building sector. This paper provides an overview on this subject, aiming at clarifying recent advances and outlining potential challenges and obstacles in building design optimization. Key discussions are focused on handling discontinuous multi-modal building optimization problems, the performance and selection of optimization algorithms, multi-objective optimization, the application of surrogate models, optimization under uncertainty and the propagation of optimization techniques into real-world design challenges. This paper also gives bibliographic information on the issues of simulation programs, optimization tools, efficiency of optimization methods, and trends in optimization studies. The review indicates that future researches should be oriented towards improving the efficiency of search techniques and approximation methods (surrogate models) for largescale building optimization problems; and reducing time and effort for such activities. Further effort is also required to quantify the robustness in optimal solutions so as to improve building performance stability.

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The aim of this paper is to investigate the effect of the change in structural weight due to optimisation experiments on life-cycle cost and earning elements using the life-cycle cost/earning model, which was developed for structure optimisation. The relation between structural variables and relevant cost/earning elements are explored and discussed in detail. The developed model is restricted to the relevant life-cycle cost and earning elements, namely production cost, periodic maintenance cost, fuel oil cost, operational earning and dismantling earning. Therefore it is important to emphasize here that the cost/earning figure calculated through the developed methodology will not be a full life-cycle cost/earning value for a subject vessel, but will be the relevant life-cycle cost/earning value. As one of the main focuses of this paper is the maintenance/repair issue, the data was collected from a number of ship operators and was solely used for the purpose of regression analysis. An illustrative example for a Chemical Tanker is provided to show the applicability of the proposed approach.

a b s t r a c tThe present article is concerned with the resistance of a ship during a collision with another ship. The paper is directly related to the so called super-elements method developed to estimate the capability of a ship to withstand to an impact. This approach consists of dividing the structure into several elements (the socalled super-elements), whose resistance to collision is evaluated individually. At the recent stage of development, the superelements method is only able to treat the case of perpendicular collision scenarios. The purpose of this paper is to go one step further, by establishing analytical formulations giving the resistance of various super-elements to an oblique impact. As a first step, the paper gives a short description of the original super-elements method. After that, analytical calculations in oblique collision cases are performed for the different superelements involved in the procedure. Finally, the formulations are validated by comparison with results provided by classical nonlinear finite element method. As a conclusion, some perspectives on the future work are presented.

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