This paper presents a shake-table test study to investigate the displacement capacity of shear-dominated reinforced masonry wall systems and the influence of wall flanges and planar walls perpendicular to the direction of shaking (out-of-plane walls) on the seismic performance of a wall system. Two fullscale, single-story, fully grouted, reinforced masonry wall specimens were tested to the verge of collapse. Each specimen had two T-walls as the seismic force-resisting elements and a stiff roof diaphragm. The second specimen had six additional planar walls perpendicular to the direction of shaking. The two specimens reached maximum roof drift ratios of 17% and 13%, without collapsing. The high displacement capacities can be largely attributed to the presence of wall flanges and, for the second specimen, also the out-of-plane walls, which provided an alternative load path to carry the gravity load when the webs of the T-walls had been severely damaged. The second specimen developed a higher lateral resistance than the first owing to the additional axial compression exerted on the T-walls by the out-of-plane walls when the former rocked. The shear resistance of the T-walls evaluated with the design code formula matches the test result well when this additional axial compression is taken into account. However, it must be understood that the beneficial influence of the wall flanges depends on the magnitude of the gravity load because of the P-Δ effect and the severity of damage induced in the wall flanges when the wall system is subjected to bidirectional ground motions. K E Y W O R D S collapse resistance, displacement capacity, flanged walls, out-of-plane walls, reinforced masonry, shake-table test, shear walls, shear-dominated behavior 1 | INTRODUCTION An accurate assessment of the displacement capacity of a building in an extreme earthquake event is of critical importance for life safety and collapse prevention. In ASCE/SEI 7-16, 1 the value of the seismic force modification factor (R) used in design has to ensure that the building has a low probability of collapse in the Maximum Considered Earthquake (MCE). 2 For reinforced masonry (RM) wall systems in high seismic areas, the value of the R factor is based on the notion that the walls can develop the necessary flexural ductility to sustain a certain amount of story drifts without collapsing when subjected to severe seismic forces. Nevertheless, in spite of the reinforcement and shear capacity design requirements in TMS 402/602 3 for RM walls designed for high seismic areas, such wall systems could still be susceptible

This article demonstrates the potential of the digital image correlation (DIC) method to provide accurate full-field deformation measurements and successfully monitor the development of damage during seismic excitation of a partially grouted reinforced masonry building. The building was subjected to a sequence of earthquake ground motion records using the Large High Performance Outdoor Shake Table at the University of California, San Diego. The DIC setup was capable of measuring surface deformations of the single-story building with high frame rate cameras located at a distance greater than 50 ft away. The accuracy of the measurements was assessed with data obtained using mounted displacement transducers. The full-field deformation data collected by the DIC system was capable to detect strain localization patterns associated with the onset of wall cracking before it could be shown by the displacement sensor data or by post mortem visual inspection. The research findings reported herein demonstrate, for the first time to the authors' best knowledge, the potential of in situ monitoring of actual structures for damage induced by non-stationary loading profiles using optical metrology.

In regions of low to moderate seismicity in North America, reinforced masonry structures are mostly partially grouted. The behavior of such structures under lateral seismic loads is complicated because of the interaction of the grouted and ungrouted masonry. As revealed in past experimental studies, the performance of partially grouted masonry (PGM) walls under in-plane cyclic lateral loading is inferior to that of fully grouted walls. However, the dynamic behavior of a PGM wall system under severe seismic loads is not well understood. In this study, a full-scale, one-story, PGM building designed for a moderate seismic zone according to current code provisions was tested on a shake table. It was shown that the structure was able to develop an adequate base shear capacity and withstand two earthquake motions that had an effective intensity of two times the maximum considered earthquake with only moderate cracking in mortar joints. However, the structure eventually failed in a brittle manner in a subsequent motion that had a slightly lower effective intensity. A detailed finite element model of the test structure has been developed and validated. The model has been used to understand the distribution of the lateral force resistance among the wall components and to evaluate the shear-strength equation given in the design code. The code equation has been found to be adequate for this structure. Furthermore, a parametric study conducted with the finite element model has shown that the introduction of a continuous bond beam right below a window opening is highly beneficial.

Modern design codes and performance‐based earthquake engineering rely heavily on computational tools to assess the seismic performance and collapse potential of structural systems. This paper presents a detailed finite‐element (FE) modeling scheme for the simulation of the seismic response of reinforced masonry (RM) wall structures. Smeared‐crack shell elements are combined with cohesive discrete‐crack interface elements to capture crushing and tensile fracture of masonry. Beam elements incorporating geometric as well as material nonlinearity are used to capture the yielding, buckling, and fracture of the reinforcing bars. The beam elements are connected to the shell elements through interface elements that simulate the bond‐slip and dowel‐action effects. An element removal scheme is introduced to enhance the robustness and accuracy of the numerical computation. The material models and interface elements have been implemented in a commercial FE analysis program. The modeling scheme is validated with data from quasi‐static cyclic tests on RM walls as well as with results from shake‐table tests on RM building systems.

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