Mechanics-based modelling of the seismic out-of-plane dynamic response of unreinforced masonry gables

Abstract

Unreinforced masonry (URM) gables, common in low-rise buildings with pitched roofs, exhibit notable vulnerability under seismic excitation, as observed in regions like Groningen, Netherlands, experiencing induced seismicity. This study introduces a computationally efficient three-degree-of-freedom (3-DOF) model to accurately predict the out-of-plane (OOP) dynamic response of URM gables under seismic loading. The model integrates global rigid-body motions induced by roof flexibility and local masonry deflections. Parameter calibration for capturing the measured response from novel shake table experiments on URM gables is conducted by employing a novel two-stage strategy based on Modified Nelder-Mead (MNM) optimization approach, enabling accurate representation of elastic and nonlinear behaviors under varied roof stiffness scenarios. Validation against full-scale incremental dynamic tests demonstrates excellent agreement in predicting the onset and progression of cracking, rocking, frictional sliding, and internal masonry degradation as well as full collapse. This simplified yet robust modeling approach offers significant potential for rapid seismic vulnerability assessment of URM structures.