BEHAVIOR OF THIN-WALLED CONCRETE BOX PIERS

The objectives of this study were to investigate experimentally and analytically the behavior of hollow, thin-walled concrete box bridge piers and pylons, and obtain methods for predicting their capacities. Twelve one-fifth-scale short concrete box pier specimens were loaded to failure under combined axial load and uniaxial bending about the weak axis. Both monolithically cast and segmentally constructed, post-tensioned specimens were tested. An analytical model was developed to predict the strength of a concrete box column subject to simultaneous oxial load and unioxial bending. This model includes the effects of local buckling of a thin compression flange. It was determined that concrete box columns with wall width-to-thickness ratios less than 15 are unaffected by local compression flange buckling. Members with wall width-to-thickness ratios of 15 or greater may exhibit reduced strengths due to local buckling. An empirical strength reduction factor is proposed to account for the effects of compression flange buckling. −