Seismic performance of reinforced concrete ductile moment-resisting frame buildings located in different seismic regions

Abstract

Seismic areas in Canada are classified into three categories for three different combinations of acceleration and velocity seismic zones (Z, < Z,, Z, = Z,,, and Za > Z,), and ground motions in different zonal combination areas are expected to have different frequency characteristics. The National Building Code of Canada specifies different levels of seismic design base shear for short-period buildings located in areas with different zonal combinations. The specification of seismic design base shear for long-period buildings is directly tied to zonal velocity, irrespective of seismic zonal combination. This paper evaluates the seismic performance of both high-rise long-period and low rise short-period reinforced concrete ductile moment-resisting frame buildings located in seismic regions having Z, < Z,, Z, = Z,, and Z, > Z,. Two frame buildings have 10 and 18 storeys were used as structural models for high-rise buildings, while a set of four-storey buildings were used to represent low-rise buildings. All buildings were designed to the current Canadian seismic provisions and concrete material code. Three groups of earthquake records were selected as representative ground motions in the three zonal combination regions. The inelastic responses of the designed buildings to the three groups of ground motions were analyzed statistically. The results indicate that the distribution of inelastic deformations is significantly different for high-rise frame buildings situated in seismic regions with Z, < Z,, Za = Z,, and Z, > Z,. Inelastic deformation is concentrated in the lower storeys for high-rise buildings located in Z, < Z, areas, whereas significant inelastic deformation can develop in the upper storeys for high-rise buildings situated in Z, > Z, regions.The use of three different levels of seismic design base shear for short-period structures improves the consistency of ductility demands on low-rise buildings situated in the three different zonal combination regions. Despite the use of appropriate design base shears for different seismic regions, the ductility demands for these low-rise buildings are relatively high. T o avoid excessive ductility demands, it is suggested that the seismic strengths for low-rise short-period buildings should not be significantly reduced from their elastic design base shears.Au Canada, les zones sismiques sont classees en trois categories selon trois differentes combinaisons de zones sismiques de vitesse et d'acceleration (Z, < Z,, Z, = Z, et Z, > Z,), et les mouvements du sol dans les regions ayant des combinaisons de zones differentes devraient avoir des caracteristiques de frequence differentes. Le Code national du bfitiment du Canada propose divers niveaux de cisaillement de calcul a la base pour les bdtiments avec periode courte situes dans des regions ayant des combinaisons de zones differentes. L'exigence de cisaillement de calcul a la base pour les bdtiments avec periode longue est directement liee a la vitesse zonale, sans tenir compte de la combinaison de zones sismiques. Cet a...

Seismic storey drift estimation

“…The various response parameters were analyzed statistically for each of the three groups of ground motions. A detailed description of the analysis procedure and the response results can be found in Zhu et al (1992). Figures 1-3 compare the interstorey drifts obtained from the inelastic dynamic analysis with those estimated from the code procedure for the 4S, 10S, and 18s frames, respectively.…”

“…The buildings were designed for combined gravity and seismic effects in accordance with NBCC9O and detailed in compliance with the Canadian Concrete Design Code (Canadian Standards Association 1984). A detailed description of the buildings and their design has been given by Zhu et al (1992).…”

Implications of structural overstrength on the calibration of seismic codes

“…The design structural overstrength is considered an inherent part of the structural overstrength, which is implicitly or explicitly accounted as a source of earthquake resisting capacity to reduce the elastic spectrum. This idea is generally accepted and it form part of the state of knowledge in earthquake engineering, see for example, ATC-10 (1982), ATC-19 (1995), ATC 34 (1995, Charney and Bertero (1982), Moehle and Diebold (1984), Miranda and Bertero (1989), Osteraas and Krawinkler (1989), Hadjian (1989), Shahrooz and Moehle (1990), Fischinger and Fajfar (1990), Nassar and Krawinkler (1991), Tso and Naumoski (1991), Zhu et al (1992), Uang (1992), Mitchell and Paultre (1994), Elnashai and Broderick (1996), Broderick and Elnashai (1996), Whittaker et al (1999) and Balendra et al (1999). In fact, values of reduction factors of modern seismic codes from 5 to 12 can only be justified if the design structural overstrength is included.…”

“…Based on this observation, a second source of earthquake-resisting capacity has been identified: the structural overstrength. In previous years, the importance of structural overstrength to resist earthquakes and its possible sources have been widely studied and reported in the technical literature (Hadjian 1989;ATC-10 1982;Miranda and Bertero 1989;Osteraas and Krawinkler 1989;Fischinger and Fajfar 1990;Shahrooz and Moehle 1990;Tso and Naumoski 1991;Zhu et al 1992;Uang 1992;Mitchell and Paultre 1994;ATC-19 1995;ATC-34 1995;Humar and Rahgozar 1996;and Rahgozar and Humar 1998).…”

Diseño Por Desempeño De Estructuras Dúctiles De Concreto Reforzado Ubicadas en La Zona Del Lago Del Distrito Federal: La Resistencia Lateral De Diseño

“…Shahrooz y Moehle (1990) 7.7 Modelo 1:4 de una estructura de seis niveles estructurada con marcos de concreto reforzado. Zhu et al (1992) R se incrementa conforme el número de pisos disminuye y conforme se reducen las fuerzas sísmicas de diseño. Jain y Navin (1995) 2.4 a 15.0 Marcos de concreto reforzado de 3, 6 y 9 niveles.…”