| The national building code of Canada (NBCC) has been under constant evolution since its first issue in 1941. Over the years, knowledge related to structural engineering and more specifically seismic response has continued to evolve through research and field investigations. Recently, the 2005 NBCC has been made available with a new perspective on seismic design, including uniform hazard spectra provided for each city for static and dynamic analyses.;Due to a greater understanding of seismic response of structures and the Canadian seismicity, the NBCC has increased the values of elastic base shears over the years. Between the 1970 and 2005 editions of NBCC, the elastic design base shear has increased by a factor as high as 2.6. A structure designed in 1970, if subjected to 2005 NBCC compatible design earthquake record would potentially be labeled as seismically deficient and fail under code specified loads. Multiple technologies currently exist to retrofit seismically deficient structures. The purpose of this research is to explore the possibilities of using diagonal prestressing, in various configurations, to increase structural stiffness and decrease lateral drift demands under seismic loading.;Shallouf (2005) successfully demonstrated experimentally that a 1 bay, 1 storey R/C frame with masonry infill panels, designed based on the ACI 318-1963 building code, hence seismically deficient, could be retrofitted with prestressed cables to reduced lateral drift. In addition, analytical modeling of the 1 storey frame and analysis of a 5 storey structure in a high seismic region (i.e. Vancouver) were used to illustrate the effectiveness of the approach. This analytical model was successful in reducing lateral drift under various prestressing patterns.;The objective of this research is to continue investigating the effectiveness of the retrofit methodology for structures in two different seismic zones, such as Vancouver and Ottawa. Also, it is examined for buildings with different heights. Structures varying between five and fifteen storeys are analyzed. The results indicate the effectiveness of high-strength prestressing cables as lateral bracing elements, while the effect of prestressing the cables changing with the dynamic characteristics of the building and their interaction with the frequency of the exciting force, i.e., earthquake record. |
