Research On The Reverse Hoisting Technology Of Ultra-large Multi-level Steel Trusses In The Frame Structure Of Nantong Nengda Building

With the rapid progress and development of the construction industry,the building structure gradually develops towards the super high-rise,large span and large space.Large-span steel structure is characterized by large volume,heavy weight,large span,high installation precision,high construction height and colorful structure,which makes the construction design and technology of building face great challenge.This paper is based on the theory of construction mechanics and combined with practical engineering practice.From the engineering application point of views,we researched large multi-level steel truss piece reverse lifting construction technology in the frame.In this paper,we have sorted out the research of domestic and foreign and the development of large-span steel structure,summarizing the structural design theory,structural analysis of mechanical construction,structural construction technology research.Then the construction method and technical principle of the super-large steel truss are reviewed and discussed.This paper summarizes the common construction methods of large span steel structures,and analyzes their advantages,disadvantages and their application.It also includes the systematic analysis and discussion on the technical requirements of steel truss,the principle of lifting point layout,the technical characteristics and principles of collapsing and unloading.Finally,the principle and method of mechanics analysis of construction process are summarized and reviewed.The influence of unloading and construction mechanics effect on the structure is explained by mechanics analysis of simple structure.This paper took Nantong Nanda Building as an example,analyzing the terms of the construction program,the computer analysis of the lifting process,the installation sequence,the overall lifting process,the control of the installation quality and the contingency plan and so on.The scheme of construction is introduced from the aspects of overall construction plan,steel truss truncation,segmentation and splicing of steel trusses,floor reinforcement measures,steel truss site assembling and reinforcement measures,upgrading of the corbel design and design of the lower anchor point;using Ansys software is to consider the lifting force during the construction of lifting;sorting the installation sequence of each lifting;the overall improvement of the process of induction is discussed by the attention of matters,enhancing the overall measurement and control,enhancing the overall closure,synchronous lifting control and truss unloading;to control the quality of products,we should check products and events,control of the quality of high-strength bolts construction,the installation notes and the comparison of each parameter and so on;the establishment of emergency rescue teams and rescue procedures and methods is used to analyse engineering emergency plan.From these aspects of the analysis of the progress of the project,we choose the plan which are in accordance with the requirements of the construction safety,economy and reasonable technical solutions.