Research And Application Of High-rise Steel Grid Box-type Cylinder-in-cylinder Hybrid Structure In High-intensity Areas

High-rise steel grid box-in-tube hybrid structure combines steel grid box-incylinder structure with concrete cylinder to coordinate forces.Reinforced concrete cylinder is set in the middle of the building as a public service area.Steel grid wall is arranged outside the building,and steel hollow sandwich plate is used to overlap the core and outer grid wall horizontally.In this paper,the seismic performance of vertical load-bearing system-steel grid wall frame,horizontal load-bearing system-steel hollow sandwich plate and whole structure of high-rise steel grid box-tube-in-tube hybrid structure are calculated and analyzed respectively.Finally,the assembly construction technology suitable for high-rise steel grid box-in-tube hybrid structure is put forward based on the existing engineering examples.The specific research contents are as follows:(1)Three common vertical load-bearing systems of frame,frame tube and steel grid wall frame are introduced.The lateral displacement formula of steel grid wall frame is deduced by flexibility method,and the accuracy of the formula is verified by an example.For the hysteretic test of steel grid wall frame,the finite element method is used to compare and analyze the three kinds of wall frames to verify the hysteretic performance of steel grid wall frame.Finally,the shear lag phenomena of tall frame columns are pointed out.Simplified models are established in two structural forms,and the shear non-uniformity coefficient is introduced.The shear lag effects of two structural forms are compared and analyzed,and the shear lag effects of grid wall frames are studied.(2)The structure and size requirements of four kinds of open-web sandwich panels,i.e.orthogonal positioning,orthogonal oblique positioning,oblique positioning and honeycomb type,are introduced.According to the mechanical characteristics of openweb sandwich panels,the stiffness matrix formation and basic assumptions of the original continuous analysis method are improved to form a continuous analysis method of quasi-sandwich panels suitable for open-web sandwich panels.Because thecalculation process of continuous analysis method is complex,it is difficult to popularize in practical engineering application.This paper also introduces the simplified calculation method of steel open-web sandwich plate,which is applicable to engineering design,so as to facilitate the popularization and application of steel openweb sandwich plate in practical engineering.The static overload performance of the full-scale steel open-web sandwich plate model under uniform load was tested,and the experimental process was simulated by workbench 19.0 finite element software to verify the experimental phenomena.(3)The steel grid box-in-tube hybrid structure combines the steel grid box-in-tube structure with the concrete cylinder,and coordinates the forces.The reinforced concrete cylinder is set in the middle of the building as a public service area.The steel grid wall is arranged outside the building.The core tube and the outer grid wall are horizontally overlapped by the steel hollow sandwich plate.Taking two high-rise residential buildings and comprehensive office buildings located in high seismic intensity area as examples,the design comparison and analysis of high-rise steel grid box-tube-in-tube hybrid structure system with conventional steel-concrete composite frame-tube and steel-concrete tube-in-tube hybrid structure system are carried out.Static elastic-plastic analysis is carried out for the selected comprehensive office building project to verify the high-rise steel grid box-in-tube hybrid structure.To verify the seismic performance of steel grid box-in-tube hybrid structure in high seismic intensity area.The analysis shows that the new structure system is "safe,reasonable,advanced and economical".The new structure system has large lateral stiffness and ductility,it is suitable for highrise buildings in high seismic intensity areas.(4)At present,there is no engineering example of high-rise steel grid box-in-tube hybrid structure,but multi-story and long-span steel grid box-in-tube structure has been built and put into use in Guizhou,Sichuan,Hebei and other provinces,using assembly construction method,and achieved better social and economic effects.Taking the Fule International School Gymnasium in Mianyang as an example,this paper introduces the assembly construction process and support system of the project,monitors the support unloading of the floor,inspects the deformation and stress after unloading,and provides a reference for the construction of high-rise steel grid box-in-tube hybrid structure.Finally,based on the similar engineering experience and the background of Kungang steel structure office building,the assembly construction technology suitable for highrise steel grid box tube-in-tube hybrid structure is introduced.