Evaluación sísmica de casas de mampostería de tierra vulnerables a modos de falla fuera del plano

Abstract

A common premise of the buildings seismic assessment is the occurrence of a global failure mode governed by in-plane failure mechanisms of walls. In the case of the traditional unconfined buildings of adobe or brick, this statement is not realistic, studies of post-seismic damage observation reveal that in these buildings the common failure mode is governed rather by out-of-plane failures mechanisms in walls. Due mainly to low connection degree between walls and between walls and floor. Thus, this work carries out of the out-of-plane failures in walls, assuming as object of study typical dwellings of the urban and rural sector in Cuenca. In the first instance, from a typological studies of adobe dwellings in Cuenca, a set of walls was stablished as study. In the second instance, based on the failure catalog revision proposed by D’Ayala y Speranza (2003), defines the most probable failure modes in function of geometric characteristics of walls. In terms to the seismic assessment of walls followed an analogous methodology (Cattari et al., 2015) to the Capacity Spectrum Method (Global in-plane failure), which consists on obtaining the performance point since the crossing between the capacity curve (represented by an effective secant period) and the demand curve (design spectrum). The obtained capacity curve is based on a tri-linear model (Doherty et al., 2002) which considered boundary conditions, connection degree, geometric parameters and collapse multipliers to represent out-of-plane failures. The seismic demand is obtained according to recommendations of the NEC-15 (2015a) for different levels of acceleration and verifying a reduction by overdamping due to incursion in the inelastic range. The final results, were presented through flow diagrams based on determinate the dominant failure mechanism in function of different geometric parameters and boundary condition of walls. This project took place within the framework of seismic vulnerability study of built heritage in Cuenca, which is conducted by “Red Sismica del Austro” (RSA).