Anti-seismic Research On The Technology Of Adding Steel Storeys On The Top Of Frame-the Core Tube Structure

Adding steel storeys on the top of the original structure is widely used in practic, for the lightness and superior anti-seismic properties. The current seismic design code has no explicit provision to the forming compound structure after adding storeys, but also it has certain limitations due to the domestic research work is mainly against the background of concrete engineering example. For the above work of investigation and research, this topic will take some problems occurred during the modification work of directly adding steel storeys on the concrete frame-the core tube structure as starting point.And combined with calculaion models of different parameters,the topic will analysis the anti-seismic behavior of the overall structure within the additional steel layer works by using a finite element analysis method,and will find out a general law so that can give reference to the future designers.This research work mainly include the following parts:⑴Reinforced concrete frame - the core tube structure adding stories for the necessity and feasibility analysis; Adding steel storeys on the top of the original structure has advantages in the reinforced concrete frame - the core tube structure adding stories retrofitting and processing after stories of the overall structure of the need for seismic research and additional stories applied to the seismic structure of the basic theory.⑵Analysis of seismic response of adding steel storeys on frame- the core tube structure:In the design of the modification work of directly adding steel storeys,as a result of the different materials from the top to bottom ,it is unreasonable to set to a value of damping ratio. The damping ratio of the overall structure should use the overall damping ratio which (energy method) calculates by the strain energy method, thus carries on the response spectrum analysis and the earthquake time-history analysis.⑶Analysis of the anti-seismic behavior influencing factors: Carriy on a comprehensive analysis of the anti-seismic behavior from the following factor: the number of adding storeys, the different placements of braces and the stiffness of column base,so as to provide the certain reference basis of the development and design method at the modification work of directly adding steel storeys on the concrete frame- the core tube structure.