Cyclic Out-of-Plane Behavior of Slender Clay Brick Masonry Walls Seismically Strengthened Using Posttensioning

Abstract

Equations for the design of a posttensioned seismic retrofit of unreinforced clay brick masonry walls are discussed, and results from an associated experimental program are reported. A total of eight full-scale multiwythe vintage solid clay brick masonry walls were subjected to uniformly distributed one-directional and reverse cyclic out-of-plane loading, of which two walls were tested as built and six walls were seismically retrofitted using unbonded posttensioning. Test wall configurations and constituent masonry materials were selected to replicate typical characteristics of historic clay brick masonry walls. The test walls were seismically retrofitted by applying varying magnitudes of posttensioning using a single tendon inserted into a cavity located at the center of each test wall. Several aspects pertaining to the seismic behavior of posttensioned masonry walls were investigated, including damage patterns, force-displacement behavior, tendon stress variation, wall secant stiffness, hysteretic energy dissipation, toughness modulus, and damping ratio. Finally, measured performance parameters of the test walls were compared with the corresponding values predicted using the proposed design equations.