Experimental Assessment of Resilient Controlled Rocking Masonry Walls with Replaceable Energy Dissipation

Abstract

In recent years, several studies have been conducted to evaluate the seismic response of controlled rocking masonry walls (CRMWs) that depend on unbonded post-tensioning (PT) tendons. The current paper describes the quasi-static cyclic testing of proposed controlled rocking masonry walls that omit PT but incorporate externally attached energy dissipation (ED-CRMWs). The proposed external energy dissipation (ED) is a flexural yielding device, named a flexural arm, that is bolted to the wall through a special steel hollow block to allow simple and fast replacement after an earthquake. As such, this wall system overcomes the limitation of internal ED devices (e.g., unbonded axial yielding bars) of being unreachable and unreplaceable after damage due to yielding or fracturing. In addition, the paper reports the retesting of the proposed controlled rocking wall after being repaired and subsequently compares the performance to that of the original wall in order to evaluate the wall resilience following seismic events. The experimental results are discussed in terms of the failure modes and damage pattern, force–displacement response, wall lateral load capacity, residual drifts, displacement ductility, and ED capacity. The results show that using a special hollow steel block at strategic locations produced a high displacement capacity of 5.0% drift without strength degradation and preserved the intended self-centering with residual drifts of less than 0.2% until at least 3.7% lateral drift. The flexural arm also had significant ductility capacity, where the walls reached 5.0% drift without buckling or fracturing of the arms. Both the original and the repaired walls exhibited limited and localized damage at the wall toes, thus positioning the proposed ED-CRMWs as a resilient system for masonry construction. Finally, the paper presents design recommendations that could be considered for introducing ED-CRMWs with flexural arms in future relevant standards.