Why must bearing properties be assigned to an integral bent cap?

Extended Question: Why must I assign bearing properties to an integral bent cap? Since bearings should always be fixed, bearing assignment does not seem relevant to girder support conditions for integral bents and abutments. How is bearing assignment used for bents and abutments with integral-girder support conditions?

Answer: While a true integral bent is fully fixed, CSI software allows the connection to have free DOF. The software connects fixed bearings to the top and bottom of a girder to model fully integral bents and abutments.

Some special cases exist, however, where behavior is more closely simulated with bearings which are not fully fixed. An example may be a steel box girder connected to superstructure girders through shear-only connections. This allows longitudinal girders to rotate relative to the cross girder, necessitating free DOF assignment within the support condition. The links used to model an integral-girder support condition for a steel-girder deck section composed of shell elements are shown in Figure 1:

Figure 1 - Integral bent links

See Also

• Bridge bearings FAQ