Analysis for Design of Bearings at Skew Bridge Supports

摘要

A three dimensional finite element discretization algorithm was established for analysis of skew steel girder bridge decks with any type of bearings. Analysis of two skew, simply-supported bridges with different end diaphragms, using the established model, has shown that: (1) Vertical components of the reactions are not equal at bearings of equally spaced stringers; (2) Assuming no yielding to take place at the bearings, substantial twisting moments and horizontal reaction components are generated, particularly at corner supports when conventional steel bolster and rocker bearings are used. These reaction components tend to lock up these bearing systems. Damage to the superstructure including buckling of the webs of the stringers and fracture of the bottom flanges at bearing locations as well as damage to the substructure manifested by longitudinal cracks and/or extrusion of lead pads from beneath the bearings may result and was observed in some skew bridges; (3) If pot bearings are used in lieu of the conventional bolster and rocker bearings, twisting moments are released, however, the horizontal reaction components still exist and their magnitudes, as well as those of the vertical reaction and components, are almost identical to those obtained with conventional bolster and rocker bearings. Comparison of measured displacements under known truck loadings with those obtained from analyses demonstrated the soundness of the analytical scheme and hence its results.