Positioning of bearings for skew bridges

Positioning of bearings for skew bridges in beam and slab construction

While designing bearings for a skew bridge with T-beam-cum-slab arrangement, correct positioning of bearings deserves special attention, so as to permit a longitudinal movement as well as a rotation of the beam ends simultaneously.

Note (based on IRC practices and international guidelines): In skew bridges with girders parallel to the bridge axis, bearings are typically placed at right angles to the girder longitudinal axis (not aligned with the skew support). This allows free expansion/contraction along the girder and accommodates rotation without inducing excessive torsion. For skew angles >20–25°, special care is needed to avoid uplift in acute corners and twisting of girders. Pot/PTFE or guided bearings are often recommended for larger skews or loads to control movement direction.

1) Small Skew and Large Skew Comparison

Small skews (up to ~25°) often allow bearings to follow the support line with minimal issues. Larger skews require staggered or guided arrangements to prevent girder twisting and uplift, especially in beam-slab systems (per SteelConstruction.info and AASHTO/NSBA guidelines).

2) Alternate for Large span and heavy loading

For large spans/heavy loads in skew T-beam bridges, pot bearings (fixed, guided, or free) or spherical bearings are preferred alternatives to simple elastomeric pads. They better accommodate combined rotation and translation while controlling direction of movement (common in IRC:83 and international practices for skewed continuous spans).

3) Comparison for wide slab or multi-girder bridges (Small span or load Vs Large span or load)

a) For Single slab

b) For multiple spans with concrete hinges (fixed bearings)

c) For multiple span multigirder Hinged column

In wide slab or multi-girder skew bridges, small spans/loads favor simpler elastomeric or fixed bearings with right-angle placement. Larger spans/loads often require advanced systems like pot bearings (fixed at one end, guided/free at others) to manage differential movements, prevent uplift, and ensure even load distribution across girders (aligned with IRC:83 and global skew bridge practices).