摘要
杭州西站项目超高层建筑转换层采用钢桁架型钢混凝土结构,其钢桁架施工质量对结构长期性能至关重要。为保障钢桁架施工精确控制,从三个方面开展钢桁架施工关键技术研究。首先,以钢结构分段重量、吊臂、吊重等为基本参数,通过分析吊重选择合适塔吊型号;理论分析堆载校核地下室顶板承载能力;基于四边简支双向板荷载分布影响,分析行车路线中地下室顶板最不利状态下承载能力,进而明确场地荷载部署,确保钢结构吊运能力满足要求。其次,通过建立钢结构三维模型将复杂结构可视化,检查封闭舱室判断浇筑施工难度。原方案中桁架层柱截面因多道腹板、横隔板交错形成了两层封闭舱室,且设计采用先封闭舱室注浆、后其他型钢混凝土结构统一浇筑的二次浇筑施工方法。基于深化的三维模型,以提高浇筑质量为原则,提出了钢柱横隔板顶面开设浇筑孔、内层舱室腹板开设流通孔,外层舱室不封闭而改为缀板连接,从而大大减小封闭空间;同时,基于扩大的横隔板孔洞,提出了改变混凝土流向的浇筑方案,以从上而下的一次性浇筑替代原有的先封闭压浆后支模浇筑的二次浇筑方案,优化钢结构构造保证浇筑成型。最后,结合塔吊吊装能力,设计桁架层施工安装流程。基于桁架安装流程,分析影响跨中变形影响因素;针对流程中关键参数跨中预拱度进行分析计算。胎架初始预设高度应由3部分位移组成,分别为有胎架支撑条件时半片桁架自重引起的跨中下挠、焊接完成拆除胎架后整体桁架因自重引起的跨中下挠和结构设计中考虑钢筋混凝土时设置的跨中预拱。采用ABAQUS建立三维实体非线性有限元模型,分别针对前述关键施工流程,计算考虑支撑刚度的施工状态下16.2 m跨径桁架层结构受力变形。结果显示:架设半侧桁架时,结构跨中挠度最大为6.41 mm;当拆除胎架后,结构跨中进一步下挠1.53 mm。为此,基于有限元计算结果,明确预拱值取值24.1 mm,约为跨径的1.5/1000。
The transfer floor of super high-rise tower in Hangzhou West Railway Station project adopts the reinforced steel-concrete structure with large steel truss prefabricated,and the construction quality of the steel truss is crucial for the long-term performance of the structure.To ensure precise control of steel truss construction,three key technologies for steel truss construction are carried out.Firstly,based on the basic parameters of steel structure segmented weight,lifting arm length,lifting capability,the suitable tower crane model is selected through comparative analysis of lifting weight.Theoretical analysis and load bearing capacity verification of the basement roof is conducted.With the consideration of load distribution on simply-supported two-way slabs,the bearing capacity of the basement roof at the most unfavorable state during the driving conditions is analyzed.The site load deployment is clarified and the steel structure lifting capacity meets the requirements.Secondly,a three-dimensional model of the steel structure is built and information are integrated.Based on visualized complex steel structure model,the difficulty of pouring construction is judged by checking the enclosed compartments.In the original plan,two closed compartments are formed due to the interlacing of multiple web plates and transverse partitions;and a secondary pouring construction method was designed by grouting the closed compartments first and then uniformly pouring other steel reinforced concrete structures.Based on three-dimensional model and the principle of improving pouring quality,the concept to enlarge pouring holes on the top surface of the steel column diaphragm,remain flow holes on the inner cabin web,and change the outer sealed plate to several battens is proposed and discussed carefully,thereby greatly reducing the enclosed space.At the same time,the diaphragm holes enlarged,one-time-concreting shaping plan is proposed by changing the concrete flow direction from top to bottom,as an alternative method of secondary pouring plan from bottom to top,optimizing the steel structure structure to ensure pouring molding.Finally,with consideration of the lifting capacity of tower crane,the construction and installation process of the steel truss structures is designed.Based on the truss installation process,the components that affect mid span deformation is analyzed and the key parameter of mid span camber in the process is calculated.The initial preset height of the bed frame should be composed of three parts of displacement,those are,the mid span deflection caused by the self weight of the half truss when supported by the bed frame,deflection caused by the self weight of the overall truss after welding and dismantling the bed frame,and displacement designed at the mid span for the pre-arch structure when reinforced concrete is considered in the structural design.A three-dimensional solid nonlinear finite element model is established by ABAQUS,and the deflection of 16.2 m span truss structure under the construction state considering the support stiffness for the aforementioned key construction processes.The results show that when installing the half truss,the maximum mid span deflection of the structure is 6.41 mm;after removing the jig frame,the structure undergoes a further downward deflection of 1.53 mm in the span.Therefore,based on the finite element calculation results,the pre arch value is determined to be 24.1 mm,which is approximately 1.5/1000 of the span.
作者
吴胜辉
李永轩
刘军
傅志华
吴承杰
夏子川
关雨晨
章玉容
Shenghui Wu;Yongxuan Li;Jun Liu;Zhihua Fu;Chengjie Wu;Zichuan Xia;Yuchen Guan;Yurong Zhang(China Construction Second Engineering Bureau Ltd.,East China Company,Shanghai 200135,China;College of Civil Engineering,Zhejiang University of Technology,Hangzhou 310014,China)
出处
《钢结构（中英文）》
2024年第9期52-59,共8页
Steel Construction（Chinese & English）
基金
浙江省水利防灾减灾重点实验室开放基金(FZJZSYS21004)。
关键词
超高层
转换层
钢桁架
吊运
钢结构安装
数值模拟
super high-rise building
transfer floor
steel truss
lifting
steel structure installation
numerical simulation
