Abstract: Due to seismic-isolation retrofit with hoop-type underpinning joints, the constraints of the structure changes during the construction process. Meanwhile, the construction is carried out in batches and sections, the differences of the construction steps and the jacking machine control mechanisms affect the structure. Thus, finite element method is adopted to simulate the construction process of the seismic-isolation retrofit the existed frame building with the hoop-type underpinning joints. The internal force and the deformation of the structure are discussed for different construction steps and caused by the nonsynchronous jacking machine control mechanisms. Some construction process suggestions and the jacking machine control mechanisms condition are given based on the rule of the internal force and deformation.This study will play a guiding role in the actual construction of seismic-isolation retrofit project, and put forward the reference opinions with numerical basis to ensure the construction safety.

Key words: frame, seismic-isolation retrofit, hoop-type underpinning joints, construction process, finite element analysis