Steel Orthotropic Plates under Alternate Loads

An experimental study of the behavior of a model on an orthotropic steel bridge deck is reported. The orthotropic plate was acted upon by static repeated loads capable of stressing the structure beyond the elastic range. The tests performed showed alternate yielding in the ribs which were directly loaded, for a P value quite lower than the static collapse; the latter was found to be very high compared to the elastic limit, confirming a well-known fact. The behavior of the model tested is finally reproduced by means of two theoretical schemes: (1) For the lower values of P the loaded ribs were considered to be an elastic-plastic beam with strain hardening. This beam is considered to be continuous on elastic supports, i.e., on transverse beams. (2) for the higher values of P, up to collapse, the orthotropic plate was considered to be a rigid-plastic grid connected to an elastic-plastic membrane, i.e., the deck plate.