Damage evaluation in steel box columns by pseudodynamic tests

The seismic response of steel box columns modeling bridge piers is studied using the pseudodynamic testing method. The concept of the pseudodynamic test is reviewed. Scaled models of steel bridge piers of box section were tested under a constant axial load and using site-specific spectrum-compatible accelerograms. The columns sustained damage in the form of local buckling, due to large deformations and low-cycle fatigue. The overall damage sustained was quantified by means of a damage index developed from theoretical considerations and cyclic loading tests. The damage index is meant to assess the safety against collapse and does not consider the serviceability requirements. Tests showed that the damage sustained depends on the structural parameters, axial load, and the parameters of the ground motion. In view of such complications the damage index seems to describe adequately the overall damage sustained under seismic loading with a minimum of computational effort.