张弦桁架壳体结构施工过程分析

Analysis on construction process of pre-stressed truss shell structure

为评价大跨度张弦桁架壳体结构在拉索施工张拉过程中的安全性及确定最优合理施工张拉方案,以北京大学体育馆张弦桁架壳体结构为研究对象,通过ANSYS有限元分析工具,采用“状态确定”的施工过程逆向分析方法并结合单元生死技术对北京大学体育馆屋盖结构进行施工过程优化分析。通过研究施工张拉顺序及张拉级数等对结构变形和构件受力的影响,对结构几何力学体系成形过程进行监控分析,确定了最优的张拉方案;并考虑了4种荷载工况及13种荷载组合,对结构在施工过程中的安全性进行了评价。分析结果表明:对于该屋盖结构,采用米字形的五级张拉方案能很好地控制结构在张拉过程中的最大位移响应和内力响应,为最优的施工张拉方案;在考虑各种不利荷载组合情况下,该屋盖结构在施工张拉过程中各类构件最大应力均低于构件的强度设计值,满足规范要求,结构安全。

To evaluate the structural safety of the long-span pre-stressed truss shell structure during the tensioning process of the cable construction and determine the optimal and reasonable construction tensioning scheme,the pre-stressed truss shell structure system of Peking University Gymnasium was taken as the research object in this study.Finite element analysis tool ANSYS was adopted,and the construction process reverse analysis method with‘state determination’and the element death and birth technology were employed to carry out the optimization analysis on the roof structure of Peking University Gymnasium.The impacts of construction and stretching sequence and stretching series on structural deformation and member stress were investigated,and the forming process of the geometrical mechanical system of structure was monitored.Finally,the optimal stretching scheme was determined.Besides,four load cases and thirteen load combinations were considered to evaluate the safety of structure during construction process.Analysis results show that for the roof structure,five-level stretching scheme with*-shaped tension sequence can well control the maximal displacement and internal force of structure during stretching,which is the optimal construction and stretching scheme.Under the consideration of various unfavorable load combinations,the maximum stress of each component is lower than the strength design value of the component during the construction of the roof structure,which meets the requirements of the code and the structure is safe.