Browsing by Author "Kotze, Mariska"
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- ItemSeismic resistance of unreinforced load-bearing masonry buildings, retrofitted with a strain-hardening cement-based composite(Stellenbosch : Stellenbosch University, 2020-03) Kotze, Mariska; Van Zijl, G. P. A. G.; Van Rooyen, G. C.; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.ENGLISH ABSTRACT: There are many low-rise unreinforced load-bearing masonry (ULM) buildings in the Western Cape, South Africa, which is a seismic zone. These buildings are susceptible to collapse should a seismic event occur. Retrofitting is proposed for these buildings in order to better withstand seismic actions. A possible retrofitting technique is to use a sprayable strain-hardening cement-based composite (SHCC) overlay. It is postulated that the SHCC overlay could sufficiently improve the ductility of the masonry buildings to prevent collapse. To determine the effect SHCC has on low-rise buildings, a non-linear finite element analysis (FEA) was done based on previous experimental and numerical testing. The previous tests comprised of masonry wallettes retrofitted with a sprayable SHCC overlay as well as tests with debonding strips between the SHCC overlay and masonry substrate. The experimental setup was replicated with FEA software and the numerical results were compared to that of the experimental tests. The numerical model was adjusted until it gave a good representation of the experimental data in terms of the diagonal shear failure and the shear force against displacement distribution. The numerical model was then used to model a typical building in the low-income areas in the Western Cape. The building was simplified to a two dimensional problem as only a quasi-static in-plane analysis was done. Two sides of the building were considered to give a qualitative representation of the building as a whole. The East side with a 7.2 m length and no openings was modelled as well as the North side with a 32 m length with various openings and a lower wall stiffness for the ground floor. The building model showed promising results as the SHCC overlay changed the failure mechanism on the East side from diagonal shear to flexural shear failure with a significant increase in the ductility and shear resistance. The North side maintained the diagonal shear failure, the shear resistance was also increased significantly but the ductility did not improve. It was concluded that the SHCC overlay could improve the seismic resistance of a low-rise ULM building. It is however recommended that further studies are done on the material parameters and that more experimental tests are needed on debonding strips and seismic loading.