The effect of vertical load on seismic response of masonry walls

The effect of the vertical load intensity on the seismic response of masonry walls is numerically investigated. A previously developed numerical model for static and dynamic analysis of masonry structures, which can simulate the most important nonlinear effects of masonry, concrete, reinforcement and soil, was used. Two–storey unreinforced and confined masonry walls, with and without openings, with good and poor quality of masonry, are analyzed. The wall foundations are supported on a rigid base, with possibility of lifting and sliding. The walls are subjected to a real earthquake and harmonic base acceleration. The characteristic displacements of the walls top, stresses in masonry and reinforcement of the vertical ring beams, as well as the state of cracks in the walls, are presented. It was concluded that larger static vertical loads of masonry walls usually have positive effects on their behavior (reducing possible tensile stresses, as well as minimizing the possibility of lifting, sliding and overturning of the walls). However, larger vertical loads generated larger inertial forces on the structure under earthquake excitation. It is more desirable to reduce the vertical load of masonry structures in areas with expected strong earthquakes.