Numerical assessment of the dynamic response of a URM terraced house exposed to induced seismicity

This paper presents the results of a numerical study aimed at extending the utility of a shake-table test on an unreinforced masonry building prototype for the seismic assessment of terraced houses in the Groningen region of the Netherlands. The area, with no recorded tectonic activity to date, has recently experienced ground shakings induced by natural-gas production. Local buildings are mostly made of unreinforced masonry, often built with cavity walls, which were not specifically conceived for earthquake resilience; hence, they do not exhibit any seismic-resistant detailing. Numerical models were first generated and fine-tuned based on data obtained from incremental unidirectional dynamic tests on a full-scale building specimen, performed up to near-collapse conditions. The structure represented the end-unit of a typical Dutch terraced building with cavity walls and a flexible timber roof. Several issues concerning the numerical simulation of the dynamic response of unreinforced cavity-wall systems were addressed in the context of employing an equivalent-frame modelling approach. Analyses were conducted also considering the effect of the nonlinear out-of-plane response of walls. The calibrated single-unit model was then enlarged to numerically assess the effects of human-induced earthquakes on an entire row of terraced houses. A cloud method was selected to establish the probabilistic relationship between ground-motion intensity and nonlinear structural response, using a large suite of records characteristic of induced-seismicity earthquakes. The question of selecting an appropriate and comprehensive measure of shaking intensity for correlation with structural performance is also discussed.