Abstract
In this paper, newly developed hybrid structural footing, in which steel grid girders are embedded, is explained in order to replace existing piers for widening double-deck superstructures. The behavior and mechanism of the hybrid structural footing under the static longitudinal and transverse loading tests are described in details. It is confirmed in the static loading tests that the longitudinal load bearing capacity of the hybrid structural footing is around three and a half times and the transverse load bearing capacity is twice of the level II earthquake load. Authors also carried out three dimensional nonlinear FEM analyses and obtained the relationship between loads and displacements, distribution of concrete cracking and stress on the steel grid girders. It is found that the analyses could simulate results of the experiments qualitatively.
