Caractérisation de l’effet de la non-linéarité sur les accélérations et spectres de plancher horizontaux dans un bâtiment en béton armé avec des murs de refend ductiles

Abstract

This project aims to evaluate the effect of the structure and non-structural components (NSC) nonlinearity, higher modes, NSC weight, the earthquake intensity, and NSC location on the seismic acceleration demands of NSCs in a ductile reinforced concrete building with shear walls when subjected to artificial earthquakes for two probabilities of exceedance, 2% and 10% over 50 years. These earthquakes are consistent with the Uniform Hazard Spectrum (UHS) of Montreal specified in the 2015 edition of the National Building Code (NBC). Seismic design of NSC is generally based on empirical equations to estimate the equivalent static forces, Vp. This equation does not take into account the dynamic properties of the NSC and the building on which they are mounted, nor the ductility of the building. For this purpose, the floor accelerations and spectra were evaluated in a 12-storey reinforced concrete building with shear walls located in Montreal. The amplification of accelerations at level x to account for the variation of NSC response in the building as a function of height (Ax), the response amplification factor (Ar) and the acceleration floor response spectra (FRS) are generated by performing linear and non-linear dynamic analysis using SAP2000® and Perform 3D softwares. The effect of the non-linearity of the supporting structure and the NSCs as well as the location of the NSCs on Ax, Ar and FRS were evaluated. Also, the seismic demands were compared with those proposed in the codes (NBC 2015, ASCE-07-16, NIST GCR 18, Eurocode 8) and a method proposed in the literature by Vukobratović et Ruggieri (2021). It was found that the nonlinear behavior of the supporting structure has a significant influence on the seismic floor acceleration demands. Increasing the damping ratio, and thus increasing the ductility (nonlinearity) of the NSC generally leads to a reduction in the FRS values. Accelerations at the NSC center of mass can differ greatly from floor accelerations. The FRS does not increase gradually with the height of the structure. The accelerations are larger near the higher modes than around the fundamental mode. Seismic demands are increased relatively with increasing CNS weight. The Ax factor suggested by the NBC 2015 is conservative for both elastic and inelastic models, except at the roof of the building where additional loads could be concentrated, while the value of Ar is underestimated. Eurocode 8 underestimates the acceleration demand on the NSC whose periods are close to the periods of higher modes of the structure. The direct method of Vukobratović et Ruggieri (2021) provided a good estimate of the FRS generally, especially in the upper floors.

Date	21 Apr 2022
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Rola Assi (Supervisor)