Seismic Evaluation of Gravity-Load-Designed Column-Grid System

This paper presents experimental research findings of gravity-load-designed perforated waffle-slab systems. The tested system is part of an industrial facility where the floor is subjected to heavy gravity loads. The presented test program consists of two reduced-scale identical specimens modeling half the height of an interior column with a portion of the waffle slab bounded by the centerlines of adjacent bays. For seismic evaluation, lateral loading is applied at the tested column end in a bidirectional quasistatic manner. The results indicate high deformation ductility of the system with minor damage to the waffle slab. The mode of failure is governed by formation of stable plastic hinging at the junction between the column and the waffle-slab joists. Special attention is given to modeling the structural response at the column-joists region. Moment transfer between the column and the floor joists is discussed through the use of curvature distributions along the floor joists.