Shaking Table Test On Existing Structure Reinforced With External Structure And Mid-story Isolation

Along with the rising number of timeworn buildings, seismic retrofitting hasbecome one of the most urgent issues in the field of disaster mitigation recent years. Asa newly developed reinforcement technique, external structure strengthening systemenhances the structural seismic performance by externally constraining the existingstructure with a new one. Furthermore, storey-adding rehabilitation can also beimplemented in conjunction with the strengthening system, which provides possibilitiesfor the application of the tuned mass damper method by the insertion of an isolationlayer between the upper structure and existing structure. However, there still exists littleresearch or technical guidelines to evaluate the seismic performance of the wholestructural system. In this paper, the seismic performance of a shear wall structurereinforced by external structure and mid-story isolation system is investigated byshaking table tests. The main contents are summarized as follows:Shaking table tests were conducted on1/6scale model of a14-storeies shear wallstructure with external structure reinforcement and an additional2-storeis steel frame onthe top. The investigation focuses on the comparison of the building’s response underdifferent level of ground motions when it is considered with and without the isolationlayer. The results indicate that the retrofitted structure remained high performancethroughout the test. Bonded by tie bars, the external structure worked well with theexisting structure, and no disjunction appeared during the tests. The isolation systemsuccessfully reduces the seismic response of the main structure without amplifying theresponse of the upper structure.Numerical analysis was performed utilizing ABAQUS software to simulate theshake table test. The simulation results agree well with available experimental results.Further analysis demonstrates that the external structures experience comparably largeoverturning moment and the foundation connection is weaken during earthquake; andthat the detrimental storey drift ratios are relatively large in lower stories, yet stillremain within the limitation of the construction code. The concrete damage mostlyappeared in lower floors and walls with discontinuous openings.