Research On Seismic Strengthening Technology Of Cable Stayed Substructure Attached To Existing Frame Structure

China is an earthquake prone country,which brings serious threat to people’s life and property.With the improvement of seismic fortification requirements,on the basis of the original "small earthquake is not bad","moderate earthquake can be repaired" and "large earthquake can not collapse",China puts forward the construction plan of "resilient city",which requires lifeline projects such as hospitals,schools,emergency command centers to maintain normal functions after the earthquake,and general buildings also require rapid recovery of functions after the earthquake.Due to the long construction period,heavy environmental pollution and limited improvement of seismic performance,the traditional seismic reinforcement methods can not meet the current higher seismic demand.Therefore,it is a new subject to develop a new and more effective seismic strengthening technology which can achieve low damage and functional recovery of existing buildings.In this paper,a new seismic strengthening technology of cable-stayed substructure attached to the existing frame structure is proposed.The technology is to attach a substructure formed by prefabricated frame and diagonal prestressed reinforcement outside the existing reinforced concrete frame structure and connect it with the existing structure as a whole.Combined with the performance-based seismic strengthening design theory,the relationship between the failure degree,story displacement and performance level of reinforced concrete frame structure under rare earthquake is proposed,which provides a quantifiable seismic performance evaluation index for higher level "resilient building".The seismic strengthening design process and simplified calculation method of external cable-stayed substructure are studied,and the main process and possible problems in construction are summarized.Through the finite element simulation analysis method,the mechanical performance of one unreinforced frame structure and four reinforced frame structures under horizontal low cyclic loading is compared.The analysis results show that the seismic bearing capacity of the frame structure strengthened with external cable-stayed substructure is significantly higher than that of the non strengthened frame;the stiffness of the strengthened structure is greatly improved,and the final residual deformation of the strengthened structure is only 1 / 5-1 / 6of the original,which realizes the self recovery of the structure,improves the ductility of the strengthened structure,and improves the energy dissipation performance;this method can make the structure more stable The results of variable parameter analysis show that increasing the number of prestressed tendons can improve the reinforcement effect.The results of finite element analysis are in good agreement with those of theoretical calculation.