Parametric studies and quantitative assessment of the vulnerability of a RC frame building exposed to differential settlements

Abstract

Abstract. The aim of this paper is to propose a simplified methodology to evaluate the mechanical performances of buildings exposed to landslide hazard, by using procedures inspired from the seismic risk analysis, such as the Capacity Spectrum Method (ATC 40, 1996). Landslide hazard involves so many aspects, that quantitative vulnerability assessment requires to consider one basic scenario at a time, i.e. one typology for the landslide hazard and one for the structural element considered. In this paper, we propose to assess vulnerability for simple one bay-one storey reinforced concrete (RC) frame structures subjected to differential settlements, using 2-D parametric nonlinear static time-history analyses. After a short review of methods used in practice to estimate building deformations induced by ground movements (e.g. differential settlements), we present the parametric studies carried out to identify the most relevant parameters, in order to predict the structural damage, as well as the methodology to develop analytical fragility curves, that can be used to quantitatively evaluate the structural vulnerability in landslide risk analyses. Different types of parameters that could influence structural behaviour have been examined in this analysis: foundation type (i.e. different combinations of links), cross-section geometry, section reinforcement degree, displacement magnitudes and displacement inclination angles. We show that the magnitude and inclination angle of displacements can be used as two relevant parameters for this type of landslide scenario. Based on these results, some simulations are conducted using the software SeismoStruct (SeismoSoft, 2003), and the proposed structural damage levels consider the local strain limits of steel and concrete constitutive materials. Some preliminary fragility curves are proposed with respect to the magnitude of differential ground displacement. It can be seen that the curves correspondCorrespondence to: C. Negulescu (c.negulescu@brgm.fr) ing to limit states LS2 (moderate damage) and LS4 (complete damage) in the present study, correspond respectively to the "tolerable settlements" "observed intolerable settlements" curves proposed by Zhang and Ng (2005).

Recommendations for the quantitative analysis of landslide risk

“…The developed method is applicable to different soil types, slope geometries and building configurations, allowing explicit consideration of various sources of uncertainty. Negulescu and Foerster (2010) also calculated vulnerability curves as a function of the differential settlements of a reinforced concrete frame building. …”

A probabilistic approach for landslide hazard analysis

“…For slow-moving landslides, intensity is generally expressed in terms of displacement rate (Hungr, 1981;Mansour et al, 2011;Frattini et al, 2013), total displacement (Rathje and Saygili, 2008;Picarelli, 2011), or differential ground deformation (Bird et al, 2005;Negulescu and Foerster, 2010). Displacement rate, however, represents a velocity, and has to be referred to a specific time interval to express the effective intensity of a landslide.…”

Vulnerability Assessment of Rc Buildings to Landslide Displacements. Application to Corniglio Case History, Italy.

“…In the second step, the building response to the statically imposed landslide differential displacement is estimated by using a Finite Element code. Four damage limit states, which describe the exceedance of slight, moderate, extensive and complete structural damage of the building (respectively LS1, LS2, LS3, LS4), were defined in terms of threshold values of structural resistance by engineering judgment and pertinent literature investigation [8,9,10]. Different limit strains are adopted for "low" and "high" code designed structures.…”