Optimization Analysis of Lifting Scheme for Multilayer Connected Structure with Discontinuous Bottom Floor
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摘要: 随着建筑钢结构的发展,高层建筑群如雨后春笋般出现,两栋高层之间设置钢连体是常见的结构形式。目前,对于常规高空连体结构安装,大多采用地面拼装后整体提升至设计位置的安装方法。但针对底层不连续的多层连体结构,一方面地面拼装胎架高,存在高空作业,不经济又不安全;另一方面拼装时底层结构需进行加固,施工繁琐。因此制定更为经济、安全、快速的施工方案是当前施工的重点。以杭州云门项目为例,给出了累积提升与分层提升两种施工方案,并对两者从结构受力变形,施工经济性、安全性、时效性等方面进行衡量比选。在受力方面,采用上述两种方案施工,对于塔楼而言,杆件应力最大值差别较小,但采用分层提升施工构件的附加应力更小,受力更为合理;对于连体而言,杆件应力最大值基本相同,但采用分层提升的杆件应力总体偏小;对于提升加强杆而言,采用分层提升方案时加强杆最大轴力为10 905.27 kN,而采用累积提升方案时加强杆最大轴力为12 615.81 kN,前者较后者减小约13.6%,因此采用分层提升方案可降低对其截面的需求,从而便于在提升完成后进行拆除。在变形方面,采用上述两种方案施工,结构最大竖向变形均位于连体跨中,且变形值相差不大;而结构最大水平变形虽均位于塔楼顶层,但变形值有些许差别,分层提升变形值较小,这是由于采用分层提升,二次提升前连体上层结构与塔楼已连成一体,具备了一定的水平刚度。在施工方面,采用累积提升方案施工,下层结构在低空安装时,上层连体结构悬停时间较长,时效性差,且连体未与塔楼形成有效连接,施工安全性差;而采用分层提升方案,上层连体结构一次提升到位后直接进行补杆工作,使连体与塔楼初步形成有效连接,届时可同步进行下层三角区结构的拼装工作,时效性、安全性更佳。在经济性方面两者相差较小,分层提升对于提升设备的数量需求较高。结果表明,针对底层不连续的多层连体结构施工,分层提升法在结构受力及变形方面,施工经济性、安全性、时效性方面表现更佳。Abstract: With the development of steel structures in buildings, high-rise building clusters have sprung up like mushrooms after a rain, and setting up steel connections between two high-rise buildings is a common structural form. At present, for the installation of conventional high-altitude connected structures, the installation method mostly uses ground assembly and overall lifting to the design position. However, for multi-layer connected structures with discontinuous bottom layers, on the one hand, the ground assembly jig frame is high, which leads to high-altitude operations, which is not economical and not safe; on the other hand, the bottom structure needs to be reinforced during assembly, which is cumbersome to construct. Therefore, how to develop a more economical, safe, and fast construction method is a consideration for construction plan developers. The article takes the Hangzhou Yunmen project as an example and provides two construction plans: cumulative lifting and layered lifting. The two are compared in terms of structural deformation, construction economy, safety, and timeliness. In terms of stress, using the above two schemes for construction, for the tower, the difference in the maximum stress value of the member is small, but the additional stress of the construction component using layered lifting is smaller, making the stress more reasonable; for connected bodies, the maximum stress values of the members are basically the same, but the overall stress of the members using layered lifting is relatively small; for the lifting reinforcement rod, the maximum axial force of the reinforcement rod using the layered lifting scheme is 10 905. 27 kN, while the maximum axial force of the reinforcement rod using the cumulative lifting scheme is 12 615. 81 kN, which is reduced by about 13. 6% compared to the latter. Therefore, using the layered lifting scheme can reduce the demand for its cross-section and facilitate removal after the lifting is completed. In terms of deformation, using the above two schemes for construction, the maximum vertical deformation of the structure is located in the middle of the connected span, and the difference in deformation values is not significant; while the maximum horizontal deformation of the structure is located at the top layer of the tower, there are some differences in deformation values. The deformation value of layered lifting is relatively small, which is due to the use of layered lifting. Before the secondary lifting, the upper structure of the connecting body and the tower have already been integrated, with a certain level of horizontal stiffness. In terms of construction, when the cumulative lifting scheme is adopted, the lower structure is installed at low altitude, the upper connected structure has a longer suspension time and poor timeliness, and the connected structure does not form an effective connection with the tower, resulting in poor construction safety; while by adopting a layered lifting scheme, the upper connected structure is directly reinforced after being lifted in place, forming an effective connection between the connected structure and the tower. At that time, the assembly work of the lower triangular area structure can be carried out simultaneously, with better timeliness and safety. In terms of economy, there is a small difference between the two, and hierarchical upgrading has a high demand for increasing the number of equipment. The results indicate that for the construction of multi-layer connected structures with discontinuous bottom layers, the layered lifting method performs better in terms of structural stress and deformation, construction economy, safety, and timeliness.
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