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 structure was a one-third-scale model that represented a structural system that is common in Mexico City and that had a high rate of damage during the 1985 Mexico earthquake. The structure was designed with widely spaced column transverse reinforcement and with closed stirrups in the slab solid heads around the columns. At failure, the specimen showed severe flexural and shear damage in columns, and large flexural distress in waffle slabs. The structure had a low lateral stiffness, which is overestimated by current building code provisions. Results also demonstrated that the specimen had relatively low energy-dissipation and displacement-ductility capacities, which are commonly associated with poor seismic behavior during strong earthquakes. It is considered that a satisfactory seismic behavior in terms of lateral stiffness and strength can only be attained by the addition of bracing or structural walls.