Overturning effects in stiffened building frames

Abstract

In this paper seismically induced overturning effects in stiffened building frames are studied by examining the response of two structures: a 20‐storey ‘core wall’ reinforced concrete frame and a 10‐storey steel braced frame. The excitations utilized in the study are the 1971 Pacoima Dam S16E Record and the 1940 El Centro N‐S Record magnified by a factor of two. Non‐linear effects of the following types are considered: plastic hinging of beams and columns, yielding and/or buckling of bracing members and transient uplift of portions of the structures from the foundation. In particular, comparisions are made between response with unlimited base overturning capacity assumed and response with dead‐weight overturning resistance only. Providing dead‐weight overturning resistance only is shown to significantly reduce seismic load levels, with relatively little or no loss in drift control. Ductility demand in these stiffened frames is shown to be limited, when transient uplift is allowed, to the link beams connecting stiffened and unstiffened portions of the structures.

Soil-Foundation-Structure Interaction with Mobilization of Bearing Capacity: Experimental Study on Sand

“…Earlier studies on rocking structures (Housner 1963;Meek 1978;Priestley et al 1978;Huckelbridge and Clough 1978;Psycharis and Jennings 1983;Chopra and Yim 1985) have indicated the beneficial role of foundation uplifting on the performance of the supported structure, particularly during severe seismic shaking. Furthermore, allowing for foundation rocking has been proposed by several researchers as an effective method of seismic isolation (Beck and Skinner 1973;Huckelbridge and Ferencz 1981;Priestley et al 1996;Mergos and Kawashima 2005;Chen et al 2006;Sakellaraki and Kawashima 2006) and has been applied in the design of modern bridges (e.g., the Rion Antirion Bridge; Pecker 2005). However, in the last decade, the research community has ventured one significant step further, acknowledging that in a way similar to pure uplifting, concurrent inelastic soil response may also help to protect the superstructure against increased seismic demands (Martin and Lam 2000;Pecker and Pender 2000;Faccioli et al 2001;Gajan et al 2005;Harden et al 2006;Pecker 2005;Gazetas et al 2007;Paolucci et al 2008;Anastasopoulos et al 2010a).…”

Inelastic displacement ratios for soil–structure systems allowed to uplift

“…A few case studies can be found in the literature in which both sources of nonlinearity, that is, inelastic behavior of the structure and the foundation uplift, are taken into account. Examples are the researches of Huckelbridge and Ferencz and Nakaki and Hart who showed that the ductility demand of the structure can be reduced when transient uplift is allowed to occur. Pecker and Chatzigogos came to the same conclusion by employing an IDA method to study the influence of nonlinear foundation behavior on the performance of a nonlinear bridge structure.…”

Effect of wall base rotation on behaviour of reinforced concrete frame-wall building

“…In recent years some researchers reported on the base rotating shear walls (1,2,3,4,5). However, the effect of base rotation of a structural wall on the behaviour of a reinforced concrete frame building is not clearly understood although a low-rise wall tends to uplift at its base rather than fail in shear or flexure, especially when the wall is supported on footing foundations.…”