| Abstract | One of the main objectives of the National Building Code of Canada (NBC) is to ensure life safety, which is described as Structural Safety objective.. To achieve this objective, the current NBC requires designers to carry out dynamic analysis of buildings; however, because of the complexity and time-consuming nature of dynamic analysis procedures, structures meeting certain limits and restrictions are permitted to be designed using an alternative analysis approach known as equivalent static force procedure. This procedure approximates the complex nonlinear dynamic response of structures by the linear response of an equivalent single-degree-of-freedom system. Because of its simplicity and effectiveness, the equivalent static force procedure has become a fundamental part of seismic design provisions of many building codes, including the NBC, and has been commonly used for the design of buildings to resist earthquakes.
Ductility-related seismic force modification factor, 𝑅𝑑, and overstrength-related seismic force modification factor, 𝑅𝑜, are key inputs for the seismic design of buildings using the equivalent static force procedure. The NBC 2020 provides values for 𝑅𝑑 and 𝑅𝑜 factors for more than 40 different SFRSs. The earthquake force on a building and the performance of the building is a function of the 𝑅𝑑 and 𝑅𝑜 values for the SFRSs used in the building. |
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