Theoretical analysis and shaking table tests of old masonry structure reinforced by external frames with added stories on the top using seismic isolation technology

Some methods are proposed by adding other stories on the top of old masonry structure and reinforcing it with external prefabricated reinforced concrete structure. To study the reinforcement and seismic isolation effect, several structural models, including the original masonry model, the reinforced masonry model, the non-isolation model (by adding stories on the top of the reinforced masonry structure without LRB) and the seismic isolation model (by adding stories on the top of the reinforced masonry structure with LRB), are established, then the dynamic response and nonlinear damage of the four types of structures are analyzed under the frequent and rare earthquake action, respectively. Based on the seismic isolation model which possesses better seismic performance in the foregoing analysis, the parameters of seismic isolation layer were optimized. In the meanwhile, the shaking table tests of 1/4 scale models are carried out to study the seismic performance of different models. The testing and the theoretical results are compared, and the results show that the base shear force of masonry structure may be greatly reduced when it is reinforced by the external prefabricated reinforced concrete wall which bears most of the shear force due to earthquake, and adding stories on the top of the reinforced structure using seismic isolation technology can further reduce the base shear force of masonry structure and improve seismic performance. For the seismic isolation model, the flexion-weight ratio was found to reach a minimum base shear force of the structure. This study may be referred for the reinforcement, reconstruction and improvement of old masonry structure.