Strengthening Scheme And Finite Elementanalysis Of Existing-structure With Story-adding Steel Structure

In recent years，steel adding storey structure is a applied widely building form, it has theadvantages of light weight，good earthquake-resistant performance and easy construction.Also, it is superior to concrete structure in aspects on technology, economy and safety,therefore this technique has a strong engineering application value in China. However, thedesign method is not mature yet, mostly, only the load bearing capacity of adding part isconsidered. But, significant differences of the whole mass, stiffness, period and dampingoccur when adding light-weight steel structure on the original building. Therefore, theanalysis of the entire structure ought to be carried out.This paper firstly summaries and discusses steel structure adding layer strengtheningscheme，column construction and structure reinforcement methods. And analyzes some keyproblems of existing-structure with story-adding steel structure.Then, the paper uses finite element analysis software ANSYS to the original five storyreinforced concrete frame structure with a layer of one and two layers respectively, The paperestablishes a frame finite element model and staticly analysis the model. Through thediscussion of connection of increasing layer structure and the original structure, the papercompares the interlayer displacement of the hinged and rigid connection. Studies show that,using the rigid form is favorable for the displacement control. The more adding story, thegreater the effect of original structure.Finally, the paper establishes different layer scheme of three-dimensional finite elementmodel though modal analysis, spectrum analysis and time-history analysis, and obtains thestructure under frequent earthquake and rare earthquake under the structure of deformation,displacement, angle of floor displacement, inter story shear parameters. It is shown from theanalysis: the lower frame structure after adding light-weight steel stories, the variation of thestress and strain is obvious in the storey of adding, so it is a vulnerable one and it should bechecked by the designer. When add more stories, the effect of high-order mode should beconsidered. In addition, it gets the rule of force and displacement about storey-adding oflight-weight steel structure, and it offers theoretical reference on the design of adding storeyfor designer.