To achieve the goal of analysis of the parameter sensitivity of concrete bridge durability under the actiion of concrete carbonatiion in atmospheric environment,the mathematic model and simulation method for the sectional degradation at three critical moments in the process of the durability degradation are proposed.

The basic course of theory of optimized design of structure from section optimization to shape optimization and topology optimization and related characteristics were described,all kinds of algorithms selected for design optimization were classified and their application scope and relevant advantages and disadvantages were also given briefly.

This paper presents the object-oriented program architecture for optimal design of tensegrity cable domes, which can be adopted in pre-press optimization, section optimization, and shape optimization.

The proposed algorithm could be applied to section optimization of large and medium reticulated domes withseveral optimum variables,and could ensure the quality of the results.

The optimality criteria(OC) method and mathematical programming(MP) were combined to found the sectional optimization model of frame structures.

The sectional optimization of truss is achieved, satisfying size, stress and local stability constraints.

Based on MSC/NASTRAN software, this paper uses the PATRAN/PCL (PATRAN Command Language) to secondly develop a new software of optimum design module for sectional optimization of truss structures.