The Seismic Behavior Research And Scheme Comparison Of Storey-Adding Out-Jacketing Structure

The method of storey-adding out-jacketing is being widely applied to engineering practices, as that it could achieve more storeys without the limit of bearing capacity of the existing structures. It can be divided into two types: separated structure and monolithic structure. The separated structure is that existing structures and newly built ones are completely separated. This kind of structure has a clear calculation diagram. However, the effective length of bottom columns is too big that the whole structure exists the weakness of rigid upside and flexible downside. By connecting the old and new structures into a whole one, the method of monolithic structure solves the problem of rigid upside and flexible downside. But the internal forces of the monolithic structure are complex and transfer load is uncertain. It is hard to evaluate the seismic behavior of the monolithic structure.Based on the above reasons, this article has done the preliminary design of one storey-adding out-jacketing structure and it’s existing structure is based on one masonry structure. Two analysis models have been established by SAP2000 software, then make comparison between the separated structure and monolithic structure by using response spectrum method and time-history method. Analyze the deformation properties and structural characteristics of the two structures. The simulated results show that it can improve the weakness of the separated structure effectively by connecting the old and new structures together.Then analyse the seismic response of the two analysis models in rare earthquake by using the method of Pushover. Contrast the internal forces changing of the existing structure before and after reform. It turns out that the method of monolithic structure can improve the weakness of rigid upside and flexible downside that the separated structure has. But it could change the internal forces and deformation behavior of the existing structure while the design of seismic reinforcement for the existing structure should be necessary.Finally, through the analysis of the monolithic structure that the stiffness ratio of two part structures and the connection style of the short beam are different, discuss the main influence factors of the seismic performance. The results show that it can enhance the constraint ability to the the newly built frame columns along the direction of short beams by increasing the stiffness of the existing structures. With the changing of the structural form connecting the old and the new structures, the seismic performance of structures is different.