Seismic Performance Of Masonry Buildings Retrofitted By Pre-Cast RC Walls

A large number of masonry structures have been built between 1960 and 1980 in downtown Beijing. The design of these buildings, however, did not consider sufficient seismic influence, and do not satisfy current seismic specifications at all. As Beijing is located in a seismic-prone area, these old masonry buildings are faced the threat from potential earthquakes, and become relatively weak in the disaster prevention project of the Capital. Traditional retrofitting methods for masonry structures bear a number of disadvantages, such as a high cost, heavy on-site work and long construction period. Moreover, a part of retrofitting work needs to be carried out in-door, thus significantly interrupt the routine life of residents.The traditional methods to retrofit masonry structures were first summarized in this dissertation. A novel retrofitting technology was then proposed. In the longitudinal direction, the exterior wall was reinforced by Precast Reinforced Concrete Walls, acronymically PRCW,"pasting"along the exterior surface, while the transverse wall was reinforced by precast reinforced concrete walls with steel bones inside, named after Precast Steel Reinforced Concrete Walls (PSRCW). Three reinforce patterns associated with PRCWs were proposed for the longitudinal exterior wall, namely "grouting mortar", "Reinforced Concrete (RC) keys" and "grouting mortar and RC keys". Correspondingly, three pieces full-scale walls were constructed and physically tested, which demonstrated that all of those reinforce techniques bring remarkable improvement for structure in terms of the ultimate strength, the ductility and the energy dissipating capacity. Nevertheless, the pattern of "grouting mortar and RC keys" was most desirable for its best capacity to coordinate the retrofitting member and the existing member.In order to examine the seismic performance of the overall retrofitted masonry structure, a five-story full-scale masonry building was constructed in the structural laboratory of Institute of Engineering Mechanics, China Earthquake Administration. It follows the specifications regulated in the Residential Standard of Masonry Structures (2nd edition, 1973) edited by Beijing Institute of Architectural Design. The building was further retrofitted by the proposed technology to simulate the real construction procedures. It demonstrated that the masonry building can be efficiently enhanced within one month. Finally, quasi-static and pseudo-dynamic tests were performed in both transversal and longitudinal directions. The test results prove an obvious improvement of seismic performance in the retrofitted masonry building.A general-purposed finite element software, i.e., ABAQUS, was employed to reproduce the wall piece tests and the five-story full-scale retrofitted building. Numerical simulation results also confirmed that retrofitted masonry structure has acceptable seismic performance.The mechanical analysis, design parameters, equations, and specifications, will be studied in the future study, but not included here because of the time limitation.