Finite-element modeling of partially encased composite columns using the dynamic explicit method

Prediction of the behavior of partially encased composite (PEC) columns by finite-element modeling presents a challenging problem due to local buckling of the thin steel flange plates and rapid volumetric expansion of the concrete near the ultimate load. The use of a dynamic explicit formulation and a concrete damage plasticity model has permitted good predictions of the capacities of both uniaxially and eccentrically loaded PEC column tests reported in the literature. The model provides good representations of the axial deformation at the peak load, the postpeak behavior, and the failure mode observed in those tests. The finite-element model is also capable of predicting the effect of different link spacings on the behavior of the PEC columns as well as determining the individual contributions of the steel and concrete to the total load carrying capacity of these columns. In addition to a description of the methodology, a discussion of the results of finite-element studies of PEC columns from three experimental programs encompassing a wide variety of geometries and loading conditions is presented in this paper. A study is also presented on the effects of local imperfections on the capacity of these columns.