SHEAR LAG EFFECT IN MULTI-CELL BOX GIRDERS

Abstract

When the axial load is applied into a wide flange by shear from the webs the flange distorts in its plane and
plane sections do not remain plane. The resulting stress distribution in the flange is not uniform. In very wide flanges,
shear lag effects have to be taken into account for the verification of stresses, especially for short spans, since it causes
the longitudinal stress at a flange-web intersection to exceed the mean stress in the flange.The distribution of bending
stress in thin-walled box girder at any transverse section is non-uniform and in general at web-flange junction the
stresses reach their maximum, decreasing towards the middle point of the top and bottom slabs and cantilever flanges.
This phenomenon of shear lag is being investigated by carrying out parametric analysis of three-cell box girder. It has
been investigated that the span and the cantilever flange of three-cell box girder plays an important role on shear lag
effect and it has been observed that shear lag effect becomes more severe as span length becomes larger and deck width
becomes wider for box girder with non-uniform thickness of deck.