三峡工程下牢溪公路桥结构优化设计

Xialaoxi Highway Bridge Structure Optimization in the Changjiang Gorges Engineering

采用改进的对偶规划法对下牢溪钢管混凝土拱桥进行优化设计。将对偶规划法中隐式性约束作了显式处理；从能量原理出发，利用单元刚度矩阵元素的物理意义推导位移敏度、内力敏度；综合运用变量轮换法、弦截法等优化方法求解对偶规划，并以结构重分析适应由形改变引起的内力调整，以获得优化解。该方法具有简便、实用等特点，特别适用于大型复杂结构（多变量）优化设计。

This paper concers about how to optimize the shape of concrete filled steel tubular (CRST) arch bridge axial curve with the improved 'Dual Theory'. It makes the concealed constrains of character apparent. From the energy principles and element stiffness matrix's physical meanings, the sensitivity of internal force and displacement are calculated, several kinds of optimum methods to solve the dual programe are synthesized, and the structure to adapt the adjustion of intrnal force caused by varying of shape are analyzed again. The results show that this method is easy and practical, and can be applied in optimum design of large and complicated structure especially with many variables.