三峡升船机下闸首工作门采用液压启闭机启闭。若按照传统方法设计启闭机机架，虽然安全，但结构自重大。采用有限元分析软件对机架结构进行静力学分析，获得结构折算应力的分布情况，再通过机架的结构拓扑优化，以结构的自重作为目标函数，得出了结构刚度最大情况下体积减少25%的材料分布伪密度分布。在此基础上，兼顾结构的制造性要求，通过改变局部结构形式、增删加强筋、改变板材厚度等手段对机架结构进行了设计改进。改进结果不仅充分满足了强度、刚度要求，且有效降低了结构的自重。

Hydraulic hoist is used for the open and close of the lower head work gate of ship lift in Three Gorges Project. The hoist frame is safe if the traditional design method is applied, but it has heavy self weight. The structure of hoist frame was performed static analysis using the finite element software to obtain the distribution of equivalent stress. In order to improve the initial design of hoist frame, the topological optimization of structure was performed. Based on the objective function of self weight, the material distribution pseudo-density of the structure was obtained from the maximum structural stiffness with 25% decreasing of volume On the basis of topological optimization results and requirements for manufacture, the frame structure was improved by the measures such as local structural change, adding or removing reinforcing ribs, and modification of plate thickness. The modified results can not only meet the requirements of strength and stiffness, but also decrease the self weight effectively.