Shear lag effect and uncertainty in concrete box girder creep

The effect of shear lag on creep deformations and stress redistributions in concrete box girder bridges is analyzed both deterministically and stochastically It is found that the shear lag is as important for creep as it is for elastic deformations Compared to bending theory predictions the shear lag causes a significant increase in the maximum longitudinal normal stress alters the stress redistributions due to a change in the structural system during the construction stage and substantially increases the deflections The statistical variability of material creep parameters and environmental factors has a significant effect on the statistical scatter of the calculated maximum longitudinal stresses and a very large effect on the statistical scatter of the predicted deflections Both the shear lag effect and the statistical variability of creep must be taken into account if a reliable design of box girder bridges from the viewpoint of long-term serviceability should be achieved.