Flexural response of skew-curved concrete box-girder bridges

The flexural response of the box-girder bridges, having curvature and skewness together referred as skew-curved bridges, cannot be predicted by simply superimposing the individual effect of skewness and curvature due to the coupling of these effects. Moreover, the complexity of such thin-walled box-girder bridges increases under eccentric vehicular loads causing additional torsional and warping stresses in the box-sections. The present study focuses on predicting the flexural response of simply supported single cell skew-curved concrete box-girder bridges. In order to investigate the effect of curvature and skewness, the central curvature angle has been varied from 0 degrees to 48 degrees at an interval of 12 degrees while the skew angle is swept from 0 degrees to 50 degrees at an interval of 10 degrees. Three-dimensional analysis models of the bridges are created using CSiBridge and a finite element analysis has been carried out for gravity loads and Indian Road Congress (IRC) specified Class 70R tracked vehicular Live Load (LL) plying at a minimum specified clearance from the kerb. The parametric study results indicate that the flexural response of the inner girder (web) becomes more pronounced in case of skew-curved bridges. In general, it has been observed that presence of skewness in highly curved bridges significantly improves the flexural response of the bridge. Furthermore, the critical position of LL producing the absolute maximum longitudinal moment as well as the location of the critical section for moment has been found significantly affected by skewness and curvature. These critical positions have been presented in the framework of newly developed 'skew-curve' coordinate system for systematic representation.