SEISMIC LOAD TESTS ON 2-STORY WAFFLE FLAT-PLATE STRUCTURE

A two-story waffle-flat-plate reinforced-concrete model structure was subjected to cyclic loading simulating a severe earthquake. The test s tructure was a one-third-scale model that represented a structural sys tem that is common in Mexico City and that had a high rate of damage d uring the 1985 Mexico earthquake. The structure was designed with wide ly spaced column transverse reinforcement and with closed stirrups in the slab solid heads around the columns. At failure, the specimen show ed severe flexural and shear damage in columns, and large flexural dis tress in waffle slabs. The structure had a low lateral stiffness, whic h is overestimated by current building code provisions. Results also d emonstrated that the specimen had relatively low energy-dissipation an d displacement-ductility capacities, which are commonly associated wit h poor seismic behavior during strong earthquakes. It is considered th at a satisfactory seismic behavior in terms of lateral stiffness and s trength can only be attained by the addition of bracing or structural walls.