Seismic Behavior of Framed Masonry Panels with Prior Damage When Subjected to Out-of-Plane Loading

Framed masonry panels are subjected to both in-plane and out-of-plane loading during earthquakes and their load-carrying capacity in the out-of-plane direction after being damaged is crucial for overall stability and safety. To assess the effect of in-plane damage on their out-of-plane behavior, three half-scaled clay brick framed masonry panels were subjected to a sequence of slow cyclic in-plane drifts and shake table-generated out-of-plane ground motions. The framed panels maintained structural integrity and out-of-plane stability even when severely damaged. Also, failure of specimens was primarily due to excessive out-of-plane deflection, rather than amplified inertia forces. Weaker interior grid elements divided masonry in smaller subpanels, and helped delay failure by controlling out-of-plane deflection and significantly enhancing the in-plane response. This subpaneling also greatly improved the in-plane response and energy dissipation potential, and consequently, the out-of-plane failure of the masonry was delayed and large in-plane drifts of up to 2.2% could be safely sustained.